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p16INK4a
Terms modified by p16INK4a Selected AbstractsProtein Expression of the Tumor Suppressors p16INK4A and p53 and Disease Progression in Recurrent Respiratory PapillomatosisTHE LARYNGOSCOPE, Issue 2 2007Truc T. Pham MD Abstract Background: Recurrent respiratory papillomatosis (RRP) is a benign condition that rarely metastasizes as invasive squamous cell carcinoma. Although this disease is associated with human papillomavirus, the role of this virus in tumorigenesis is unclear. Objectives: The aim of this study is to assess the involvement of the tumor suppressors P16INK4A and p53 in RRP tumor progression. Design: Immunohistochemistry of p16INK4A and p53 was performed on biopsies of recurrent squamous papillomas and invasive lesions in nine patients. Results: Twenty biopsies were graded as papillomas (RP), three as papillomas with high-grade dysplasia/carcinoma in situ (HGD/CIS), and two as invasive squamous cell carcinoma (SCCA). Forty-five percent of RP and 60% of HGD/CIS/SCCA expressed p16INK4A. Fifty percent of RP and 100% of HGD/CIS/SCCA expressed p53. The difference in the frequency of p53-positive staining between HGD/CIS and SCCA (100% of tissues examined) and RP (50% of tissues examined) approached statistical significance. Neither p16INK4A nor p53 was predictive of invasive transformation. Conclusions: Expression of p16INK4A, which is a surrogate for the tumor suppressor retinoblastoma (Rb), did not immediately lead to invasive disease. There is no correlation between disease severity of RRP and level of p16INK4A. [source] Human Papillomavirus and Overexpression of P16INK4a in Nonmelanoma Skin CancerDERMATOLOGIC SURGERY, Issue 3 2004Ingo Nindl PhD Background. P16INK4a overexpression has been identified as a specific biomarker in high-risk human papillomavirus (HPV),infected cervical (pre)cancer lesions. Objective. To evaluate the overexpression of this cyclin-dependent kinase inhibitor in skin tumors depending on HPV infections, we analyzed normal skin, benign skin disease, and skin cancer specimens. Methods. Biopsies of 23 patients with normal histology (3), psoriasis (2), verrucae vulgaris (2), actinic keratoses (5), squamous cell carcinoma (SCC) in situ (3), Bowen's carcinoma (1), and SCC (7) were analyzed. Specimens of 23 patients were immunostained using the monoclonal antibody E6H4 specific for p16INK4a. HPV status was assessed by a polymerase chain reaction (PCR) system to detect all currently known HPV types. MY (MY09/MY11 and MYN9/MYN10)-, CP (CP65/CP70 and CP66/CP69)-nested PCR, and three single PCR methods CN1, CN3, and CN4 were used in a first step, and HPV typing was performed by restriction fragment length polymorphism analysis. Only ,-globin,positive patients were included in this study. Results. HPV DNA was detected in all actinic keratoses, SCC in situ, Bowen's carcinoma, and SCC, in 50% (one of two) of verrucae vulgaris, in 66% (two of three) of normal skin, and in none of two psoriasis. P16INK4a expression was not detected in normal skin, psoriasis, and verrucae vulgares. Overexpression of p16INK4a was detected in a subset of dysplastic cells (10% to 80%) of all skin (pre)cancer lesions such as actinic keratoses, SCC in situ, Bowen's carcinoma, and SCC infected with HPV independent of sun exposure. Conclusion. P16INK4a appears to be overexpressed in a portion of dysplastic cells from actinic keratoses and SCC. Further studies to examine the association of HPV infection and the overexpression of p16INK4a are warranted. [source] Detection of human papilloma virus subtypes 16 and P16ink4a in invasive squamous cell carcinoma of the fallopian tube and concomitant squamous cell carcinoma in situ of the cervixJOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 2 2009Zhiqin Wang Abstract Squamous cell carcinoma (SCC) of the fallopian tube is rare and often diagnosed postoperatively. Cervical cancer is considered as a long-term sequaele, resulting from sexual transmitted infection with certain common high-risk human papilloma virus (HPV) types. The role of human papilloma virus in the development of the tubal SCC is unknown. We report an unusual case of SCC of the fallopian tube, synchronously occurring with cervical SCC in situ in a 49-year-old patient. Histological examination of the entire endometrium revealed no involvement. Both tubal and cervical lesions showed the presence of high risk HPV 16 by PCR and increased expression of p16INK4a protein. Both SCC of the fallopian tube and cervical SCC in situ were positive for p63, while the non-involved tubal epithelium was positive for WT-1, but negative for p63. In conclusion, the concomitant occurrence of fallopian tube and cervical SCC can be explained by: (i) the ,field effect' of HPV infection resulting in the concomitant development of primary SCC in various sites of the female genital tract; (ii) the primary fallopian tube SSC metastasizing to the uterine cervix; or (iii) primary cervical SCC metastasizing to the fallopian tube. The detection of HPV 16 and p16INK4a in both the fallopian tube and cervical SCCs strengthens the hypothesis of the ,field effect' of HPV infection. [source] Synchronous high-grade squamous intraepithelial lesion and adenocarcinoma in situ of cervix in a young woman presenting with hyperchromatic crowded groups in the cervical cytology specimen: Report of a caseDIAGNOSTIC CYTOPATHOLOGY, Issue 11 2008Nadeem Zafar M.D. Abstract We report a 29-year-old woman who underwent routine gynecologic evaluation at a community clinic and had a cervical sample drawn for liquid-based cytologic evaluation. At cytology, many hyperchromatic crowded groups (HCG) were present, but a consensus could not be established whether the abnormal cells were primarily glandular or squamous with secondary endocervical glandular involvement. An interpretation of atypical endocervical cells, favor neoplastic, was rendered and biopsy advised if clinically appropriate. At biopsy, the cervix contained synchronous squamous cell carcinoma in situ, secondarily involving endocervical glands, and neighboring adenocarcinoma in situ. Immunohistochemistry for Ki-67 and p16INK4A crisply and precisely stained both the lesions, clearly separating them from the adjacent uninvolved mucosa. This case re-emphasizes the challenge associated with accurate evaluation of HCG at cytology, the significance of ancillary testing for surrogate markers of high-risk HPV (HR-HPV) infection, the need for adjunct testing for HPV-DNA in the setting of HCG at cervical cytology, and a recommendation to set up studies to evaluate the role of surrogate markers of HR-HPV infection in cytologic samples with HCG. Diagn. Cytopathol. 2008;36:823,826. © 2008 Wiley-Liss, Inc. [source] Comparison of p16INK4A and Hybrid Capture® 2 human papillomavirus testing as adjunctive tests in liquid-based gynecologic SurePathÔ preparationsDIAGNOSTIC CYTOPATHOLOGY, Issue 3 2008Aziza Nassar M.D., F.I.A.C. Abstract p16INK4a, cyclin-dependent kinase inhibitor, is functionally inactivated in many tumors, including cervical cancer. We compared p16INK4A immunocytochemical staining and Hybrid Capture® 2 (HCII) on SurePathÔ specimens using tissue biopsies (as the gold standard). Their utility in a spectrum of atypical and preneoplastic lesions, and their ability to accurately identify underlying lesions of CIN II or greater was assessed using biopsy follow-up data. One-hundred and seventeen residual SurePathÔ samples were collected: 43 atypical squamous cells of undetermined significance (ASCUS), 47 low-grade (LGSIL), and 27 high-grade (HGSIL) squamous intraepithelial lesions. Two slides were prepared from each sample; one stained with the SurePathÔ autocyte stain and one immunostained using the CINtecÔ p16INK4a Cytology Kit (Dakocytomation). High-risk HPV testing was performed using the HCII DNA test (Digene, Gaithersburg, MD). Available tissue biopsy follow-up data was retrieved. p16INK4a was positive in 32.6% (14/43) ASCUS, 46.8% (22/47) LGSIL, and 48.1% (13/27) HGSIL specimens. HCII DNA test was positive in 41.9% (18/43) ASCUS, 78.7% (37/47) LGSIL, and 96.3% (26/27) HGSIL samples. The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values of p16INK4a and HCII were: 58.7% and 89.8%, 58.6% and 34.6%, 69.2% and 72.1%, 47.2% and 64.3%, respectively. In patients with cervical biopsies, the PPV of HCII (92.3%) results for a biopsy with CINII/III was significantly higher than the PPV of p16INK4a (52%) (P = 0.001). Using liquid-based cytology specimens, HCII is a more sensitive test than p16INK4a for detection of abnormal cytology. HCII has a higher PPV than p16INK4a for identifying CIN II/III. Diagn. Cytopathol. 2008;36:142,148. © 2008 Wiley-Liss, Inc. [source] Application of flow cytometry for biomarker-based cervical cancer cells detectionDIAGNOSTIC CYTOPATHOLOGY, Issue 2 2008Jian Ling Ph.D. Abstract The Pap test used for cervical cancer screening is subjective, labor-intensive, and has relatively low sensitivity and specificity for the detection of underlying clinically significant lesions. The objective of this study is to develop a biomarker/flow cytometry-based approach for cervical cancer screening. Immunofluorescence technology to quantify cervical cell expression of two biomarkers p16INK4A and Mcm5 was developed and evaluated by both microcopy and flow cytometry. The capability of using biomarker/flow cytometry approach to detect rare-event dysplastic cells in a large background of benign epithelial and inflammatory cells was evaluated. The results indicate that flow cytometry could detect 0.01% dysplastic cells in a background of normal cervical epithelial cells with the combination of the two biomarkers. Thirty-two clinical specimens were used to test the biomarker/flow cytometry-based approach and the results were compared with the liquid-based cervical cytology. The experiment yielded 100% sensitivity and 93% specificity with reference to the liquid-based cervical cytology. This study indicates the promise of using multi-color fluorescence flow cytometry for biomarker-based cervical cancer screening. This molecular-based, potentially high-throughput and automated method is expected to provide an alternative/auxiliary means of cervical cancer screening. Diagn. Cytopathol. 2008;36:76,84. © 2008 Wiley-Liss, Inc. [source] A large Norwegian family with inherited malignant melanoma, multiple atypical nevi, and CDK4 mutationGENES, CHROMOSOMES AND CANCER, Issue 1 2005Anders Molven Mutations in two loci encoding cell-cycle-regulatory proteins have been shown to cause familial malignant melanoma. About 20% of melanoma-prone families bear a mutation in the CDKN2A locus, which encodes two unrelated proteins, p16INK4A and p14ARF. Mutations in the other locus, CDK4, are much rarer and have been linked to the disease in only three families worldwide. In the 1960s, a large Norwegian pedigree with multiple atypical nevi and malignant melanomas was identified. Subsequently, six generations and more than 100 family members were traced and 20 cases of melanoma verified. In this article, we report that CDK4 codon 24 is mutated from CGT to CAT (Arg24His) in this unusually large melanoma kindred. Intriguingly, one of the family members had ocular melanoma, but the CDK4 mutation could not be detected in archival tissue samples from this subject. Thus, the case of ocular melanoma in this family was sporadic, suggesting an etiology different from that of the skin tumors. The CDK4 mutation in the Norwegian family was identical to that in melanoma families in France, Australia, and England. Haplotype analysis using microsatellite markers flanking the CDK4 gene and single-nucleotide polymorphisms within the gene did not support the possibility that there was a common founder, but rather indicated at least two independent mutational events. All CDK4 melanoma families known to date have a substitution of amino acid 24. In addition to resulting from selection pressure, this observation may be explained by the CG dinucleotide of codon 24 representing a mutational hot spot in the CDK4 gene. © 2005 Wiley-Liss, Inc. [source] The expression of key cell cycle markers and presence of human papillomavirus in squamous cell carcinoma of the tonsilHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 1 2004Wei Li MMed Abstract Background. Chemical carcinogens induce squamous cell carcinoma (SCC) of the head and neck by targeting the p53 and the retinoblastoma (pRb) pathways. Human papillomavirus (HPV) might have an etiologic role in these cancers at particular sites. Few studies have compared cell cycle protein expression in HPV-positive and HPV-negative tumors in this region. Methods. Fifty tonsil SCCs were analyzed for HPV by PCR and for expression of cell cycle proteins (p53, pRb, p16INK4A, p21CIP1/WAF1, p27KIP1, and cyclinD1) by immunohistochemistry. Results. HPV was present in 42%; almost all were type 16. There were statistical associations between HPV positivity and reduced expression of pRb and cyclinD1, overexpression of p16, and younger patient age. Tumor with down-regulated p27 tended to have down-regulated pRb and p21. Conclusions. HPV-positive tonsil SCCs have distinct molecular pathways. Their association with younger patient age suggests that they are biologically distinct from HPV-negative tumors. © 2004 Wiley Periodicals, Inc. Head and Neck 26: 1,9, 2004 [source] Cell cycle deregulation in liver lesions of rats with and without genetic predisposition to hepatocarcinogenesisHEPATOLOGY, Issue 6 2002Rosa M. Pascale Preneoplastic and neoplastic hepatocytes undergo c-Myc up-regulation and overgrowth in rats genetically susceptible to hepatocarcinogenesis, but not in resistant rats. Because c-Myc regulates the pRb-E2F pathway, we evaluated cell cycle gene expression in neoplastic nodules and hepatocellular carcinomas (HCCs), induced by initiation/selection (IS) protocols 40 and 70 weeks after diethylnitrosamine treatment, in susceptible Fisher 344 (F344) rats, and resistant Wistar and Brown Norway (BN) rats. No interstrain differences in gene expression occurred in normal liver. Overexpression of c- myc, Cyclins D1, E, and A, and E2F1 genes, at messenger RNA (mRNA) and protein levels, rise in Cyclin D1-CDK4, Cyclin E-CDK2, and E2F1-DP1 complexes, and pRb hyperphosphorylation occurred in nodules and HCCs of F344 rats. Expression of Cdk4, Cdk2, p16INK4A, and p27KIP1 did not change. In nodules and/or HCCs of Wistar and BN rats, low or no increases in c- myc, Cyclins D1, E, and A, and E2F1 expression, and Cyclin-CDKs complex formation were associated with p16INK4A overexpression and pRb hypophosphorylation. In conclusion, these results suggest deregulation of G1 and S phases in liver lesions of susceptible rats and block of G1-S transition in lesions of resistant strains, which explains their low progression capacity. [source] A panel of p16INK4A, MIB1 and p53 proteins can distinguish between the 2 pathways leading to vulvar squamous cell carcinomaINTERNATIONAL JOURNAL OF CANCER, Issue 12 2008Brigiet M. Hoevenaars Abstract Two pathways leading to vulvar squamous cell carcinoma (SCC) exist. The expression of proliferation- and cell-cycle-related biomarkers and the presence of high-risk (hr) HPV might be helpful to distinguish the premalignancies in both pathways. Seventy-five differentiated vulvar intra-epithelial neoplasia (VIN)-lesions with adjacent SCC and 45 usual VIN-lesions (32 solitary and 13 with adjacent SCC) were selected, and tested for hr-HPV DNA, using a broad-spectrum HPV detection/genotyping assay (SPF10 -LiPA), and the immunohistochemical expression of MIB1, p16INK4A and p53. All differentiated VIN-lesions were hr-HPV- and p16-negative and in 96% MIB1-expression was confined to the parabasal layers. Eighty-four percent exhibited high p53 labeling indices, sometimes with parabasal extension. Eighty percent of all usual VIN-lesions were hr-HPV-positive, p16-positive, MIB1-positive and p53-negative. Five (of seven) HPV-negative usual VIN lesions, had an expression pattern like the other HPV-positive usual VIN lesions. In conclusion, both pathways leading to vulvar SCC have their own immunohistochemical profile, which can be used to distinguish the 2 types of VIN, but cannot explain differences in malignant potential. © 2008 Wiley-Liss, Inc. [source] The increased expression of Y box-binding protein 1 in melanoma stimulates proliferation and tumor invasion, antagonizes apoptosis and enhances chemoresistanceINTERNATIONAL JOURNAL OF CANCER, Issue 10 2007Birgit Schittek Abstract In previous studies we identified the transcription/translation factor Y-box-binding protein (YB-1) as a gene that is upregulated in primary melanoma and melanoma metastases when compared to benign melanocytic nevi. To analyze whether YB-1 expression correlates with melanoma progression in vitro and in vivo, we performed expression analysis on melanoma cell lines representing different stages of melanoma progression and on tissues of melanocytic nevi, primary melanoma and melanoma metastases. Our data indicate that compared to benign melanocytes YB-1 expression is increased in melanoma cells in vitro and in vivo and that YB-1 is translocated into the nucleus in invasive and metastatic melanoma cells. To reveal the functional role of YB-1 in melanoma progression we achieved a stable downregulation of YB-1 using shRNA in metastatic melanoma cells. Interestingly, YB-1 downregulation resulted in a pronounced reduced rate of proliferation and an increased rate of apoptotic cell death. In addition, migration and invasion of melanoma cells in monolayer and in a three-dimensional skin reconstruct in vitro was significantly reduced. These effects were accompanied by downregulation of genes involved in proliferation, survival and migration/invasion of melanoma cells such as MMP-2, bcl-2, Cyclin D1, p53 and p16INK4A. Furthermore, melanoma cells with a reduced YB-1 expression showed a decreased resistance to the chemotherapeutic agents cisplatin and etoposide. These data suggest that YB-1 is involved in malignant transformation of melanocytes and contributes to the stimulation of proliferation, tumor invasion, survival and chemoresistance. Thus, YB-1 may be a promising molecular target in melanoma therapy. © 2007 Wiley-Liss, Inc. [source] Methylation profile in tumor and sputum samples of lung cancer patients detected by spiral computed tomography: A nested case,control studyINTERNATIONAL JOURNAL OF CANCER, Issue 5 2006Rosalia Cirincione Abstract We evaluated the aberrant promoter methylation profile of a panel of 3 genes in DNA from tumor and sputum samples, in view of a complementary approach to spiral computed tomography (CT) for early diagnosis of lung cancer. The aberrant promoter methylation of RAR,2, p16INK4A and RASSF1A genes was evaluated by methylation-specific PCR in tumor samples of 29 CT-detected lung cancer patients, of which 18 had tumor-sputum pairs available for the analysis, and in the sputum samples from 112 cancer-free heavy smokers enrolled in a spiral CT trial. In tumor samples from 29 spiral CT-detected patients, promoter hypermethylation was identified in 19/29 (65.5%) cases for RAR,2, 12/29 (41.4%) for p16INK4A and 15/29 (51.7%) for RASSF1A. Twenty-three of twenty-nine (79.3%) samples of the tumors exhibited methylation in at least 1 gene. In the sputum samples of 18 patients, methylation was detected in 8/18 (44.4%) for RAR,2 and 1/18 (5%) for both RASSF1A and p16INK4A. At least 1 gene was methylated in 9/18 (50%) sputum samples. Promoter hypermethylation in sputum from 112 cancer-free smokers was observed in 58/112 (51.7%) for RAR,2 and 20/112 (17.8%) for p16, whereas methylation of the RASSF1A gene was found in only 1/112 (0.9%) sputum sample. Our study indicates that a high frequency of hypermethylation for RAR,2, p16INK4A and RASSF1A promoters is present in spiral CT-detected tumors, whereas promoter hypermethylation of this panel of genes in uninduced sputum has a limited diagnostic value in early lung cancer detection. © 2005 Wiley-Liss, Inc. [source] Immunocytochemistry in liquid-based cervical cytology: Analysis of clinical use following a cross-sectional studyINTERNATIONAL JOURNAL OF CANCER, Issue 5 2006Shaira Sahebali Abstract Cytological screening for cervical cancer is hampered by imperfect sensitivity and low inter-observer reproducibility. Human papillomavirus (HPV) testing lacks specificity as a primary screening method. Studies indicate that immunocytochemical detection of alterations caused by HPV in the host cells can optimise screening. Here, the potential of p16INK4a (cyclin-dependent kinase inhibitor p16) and MIB-1 (Ki-67 proliferation marker) as adjunct molecular markers for cervical lesions was investigated in a prospective, cross-sectional study of 500 samples in the framework of opportunistic screening in Flanders, Belgium. A consecutive series of 200 samples and 100 samples from the cytological categories ASC, LSIL and HSIL were investigated. Surepath samples were interpreted according to the Bethesda 2001 reporting system. HPV testing was done with MY09/MY11 consensus PCR. Immunocytochemistry for p16INK4a and MIB-1 was performed with an automated staining protocol. The number of immunoreactive cells/1,000 cervical cells was assessed. There was a higher mean number of p16INK4A and MIB-1 immunoreactive cells/1,000 cells in HSIL (4.06 ± 1.93 and 11.13 ± 2.83, respectively) compared to other cytological categories. Both markers showed a large spread in counts, for all categories. In cases of HSIL without immunoreactive cells for either marker, low cellularity and long-term storage in water were often the cause of false negativity. This study confirms that positive staining for p16INK4a and MIB-1 is highly correlated with presence of high-grade lesions. These markers could be used as adjuncts to increase the sensitivity of cytological screening as well as the specificity of the HPV test. However, clear methodological standards are needed for optimal performance of immunocytochemistry in a clinical setting. © 2005 Wiley-Liss, Inc. [source] In vitro and in vivo tumor growth inhibition by a p16-mimicking peptide in p16INK4A -defective, pRb-positive human melanoma cellsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2005Douglas M. Noonan The cell cycle regulatory pathway responsible for the control of the late-G1 checkpoint is found recurrently altered in human malignant melanoma, often due to lack of functional p16 or pRb (pRb-1) proteins. Here we examined the ability of p16-derived peptides to mimic p16 function in two exemplary human melanoma cell lines: the p16-defective, pRb-positive A375M cells and p16-positive, pRb-defective A2058 cells. The synthetic p16-mimicking peptides strongly induced apoptosis in p16,, pRb+ A375M cells in vitro, while they had significantly less activity on p16+, pRb, A2058 cells. The most active p16-mimicking peptide, p16-AP9, also potently inhibited in vivo growth of the A375M melanoma. Treated tumors showed a threefold smaller volume (P,<,0.025) and a significant reduction of the mitotic index and of PCNA expression. Growth of A2058 cells in vivo was not affected by treatment with the p16-mimicking peptide. Our results demonstrate that p16-mimicking peptides can induce apoptosis in vitro and that can inhibit tumor growth in vivo in p16-defective, pRb-expressing human melanoma cells, suggesting that p16-mimicking peptides can represent a promising tool for targeted therapy in selected cancer phenotypes. © 2004 Wiley-Liss, Inc. [source] Epigenetics are involved in the regulation of the cell cycle and expression of tumor suppressor genes in human colon cancer cellsJOURNAL OF DIGESTIVE DISEASES, Issue 3 2003Ying Xuan CHEN OBJECTIVE: To investigate the effects of DNA methylation and histone acetylation on the cell cycle progression and expression of tumor suppressor genes in human colon cancer (HCC) cell lines. METHODS: Three HCC cell lines (HT-29, SW1116 and Colo-320) were treated with the DNA methylation inhibitor, 5-aza-2'-deoxycytidine (5-aza-dC) or/and histone deacetylase (HDAC) inhibitors, trichostatin A (TSA) or sodium butyrate. The methylation status of the promoter of the p16INK4A gene was assayed by methylation-specific PCR (MSP). The expression of p16INK4A and p21WAF1 was analyzed by RT-PCR. The cell cycle distribution was determined by flow cytometry. RESULTS: Before treatment, p16INK4A expression was slightly detected in the three cell lines (HT-29, SW1116 and Colo-320) and p21WAF1 expression was not detected in SW1116 and Colo-320 cells. The methylation level of the p16INK4A gene promoter significantly decreased and mRNA expression markedly increased in HT-29 cells after treatment with 1 µmol/L, but not 10 µmol/L, of 5-aza-dC for 24 h. In the SW1116 and Colo-320 cells, the expression of p16INK4A was markedly enhanced at 10 µmol/L or 5 µmol/L of 5-aza-dC for 24 h. However, p21WAF1 gene expression was not detected. Interestingly, after treatment with TSA or sodium butyrate, the transcription of p21WAF1 was significantly upregulated in these two cell lines. Furthermore, 5-aza-dC did not affect cell cycle distribution, but TSA or sodium butyrate blocked the cell cycle, mainly in the G1 phase. CONCLUSIONS: The expression of the p16INK4A gene is regulated by DNA methylation in three HCC cell lines. The expression of p21WAF1 gene is regulated by histone acetylation in SW1116 and Colo-320. In these two cell lines, histone hyperacetylation causes a G1 cell cycle arrest. [source] Protein Expression of the Tumor Suppressors p16INK4A and p53 and Disease Progression in Recurrent Respiratory PapillomatosisTHE LARYNGOSCOPE, Issue 2 2007Truc T. Pham MD Abstract Background: Recurrent respiratory papillomatosis (RRP) is a benign condition that rarely metastasizes as invasive squamous cell carcinoma. Although this disease is associated with human papillomavirus, the role of this virus in tumorigenesis is unclear. Objectives: The aim of this study is to assess the involvement of the tumor suppressors P16INK4A and p53 in RRP tumor progression. Design: Immunohistochemistry of p16INK4A and p53 was performed on biopsies of recurrent squamous papillomas and invasive lesions in nine patients. Results: Twenty biopsies were graded as papillomas (RP), three as papillomas with high-grade dysplasia/carcinoma in situ (HGD/CIS), and two as invasive squamous cell carcinoma (SCCA). Forty-five percent of RP and 60% of HGD/CIS/SCCA expressed p16INK4A. Fifty percent of RP and 100% of HGD/CIS/SCCA expressed p53. The difference in the frequency of p53-positive staining between HGD/CIS and SCCA (100% of tissues examined) and RP (50% of tissues examined) approached statistical significance. Neither p16INK4A nor p53 was predictive of invasive transformation. Conclusions: Expression of p16INK4A, which is a surrogate for the tumor suppressor retinoblastoma (Rb), did not immediately lead to invasive disease. There is no correlation between disease severity of RRP and level of p16INK4A. [source] CDKN2A promoter methylation is related to the tumor location and histological subtype and associated with Helicobacter pylori flaA(+) strains in gastric adenocarcinomasAPMIS, Issue 4 2010MARKÊNIA KÉLIA SANTOS ALVES Alves MKS, Lima VP, Ferrasi AC, Rodrigues MA, de Moura Campos Pardini MI, Rabenhorst SHB. CDKN2A promoter methylation is related to the tumor location and histological subtype and associated with Helicobacter pylori flaA(+) strains in gastric adenocarcinomas. APMIS 2010; 118: 297,307. Promoter hypermethylation of CDKN2A (p16INK4A protein) is the main mechanism of gene inactivation. However, its association with Helicobacter pylori infection is a controversial issue. Therefore, we examined a series of gastric adenocarcinomas to assess the association between p16INK4A inactivation and H. pylori genotype (vacA, cagA, cagE, virB11 and flaA) according to the location and histological subtype of the tumors. p16INK4A expression and CDKN2A promoter methylation were found in 77 gastric adenocarcinoma samples by immunohistochemistry and methylation-specific PCR, respectively. Helicobacter pylori infection and genotype were determined by PCR. A strong negative correlation between immunostaining and CDKN2A promoter region methylation was found. In diffuse subtype tumors, the inactivation of p16INK4A by promoter methylation was unique in noncardia tumors (p = 0.022). In addition, H. pylori -bearing flaA was associated with non-methylation tumors (p = 0.008) and H. pylori strain bearing cagA or vacAs1m1 genes but without flaA was associated with methylated tumors (p = 0.022 and 0.003, respectively). Inactivation of p16INK4A in intestinal and diffuse subtypes showed distinct carcinogenic pathways, depending on the tumor location. Moreover, the process of methylation of the CDKN2A promoter seems to depend on the H. pylori genotype. The present data suggest that there is a differential influence and relevance of H. pylori genotype in gastric cancer development. [source] Prognostic significance of O6 -methylguanine DNA methyltransferase and p57 methylation in patients with diffuse large B-cell lymphomasAPMIS, Issue 2 2009SUN MI LEE To evaluate whether promoter methylation is related to responsiveness for chemotherapy or clinical outcome, we performed an association analysis between methylation and clinical outcomes. Patients with nodal diffuse large B-cell lymphomas (DLBCL) at a single institute (n=44) were studied for methylation of tumor-related genes, MGMT, p15INK4B, p16INK4A, p16INK4A, Mad2, TMS1/ASC, CASP8, and GSTP1. The clinical behavior of DLBCL after chemotherapy was followed up and analyzed. Hypermethylation of promoters of MGMT, p15INK4B, p16INK4A, p16INK4A, Mad2, and TMS1/ASC genes was observed in 52.3%, 31.8%, 54.5%, 47.7%, 50%, and 2.3% of the cases, respectively. Methylation of CASP8 and GSTP1 genes was not observed. Promoter methylation was not related to chemo-responsiveness, disease-free survival, and progress of disease after chemotherapy. However, in overall survival analyses, MGMT methylation (p<0.05) and responsiveness to chemotherapy (p<0.01) were significant prognostic factors in patients with DLBCL. In the low-risk group, patients with p57 methylation showed longer overall survival than patients without p57 methylation (p=0.02) and all patients with p57 methylation were alive during follow-up. Our results demonstrate that aberrant promoter methylation of MGMT and p57 is an additional biological marker for predicting increased overall survival in patients with DLBCL. [source] Human papillomavirus-associated increase in p16INK4A expression in penile lichen sclerosus and squamous cell carcinomaBRITISH JOURNAL OF DERMATOLOGY, Issue 2 2008D.M. Prowse Summary Background, Human papillomaviruses (HPVs) are sexually transmitted human carcinogens that may play a role in the oncogenesis of penile cancer. Objectives, To investigate the role of HPV infection and expression of the tumour suppressor protein p16INK4A in the pathogenesis of penile cancer. Methods, By means of polymerase chain reaction amplification and reverse hybridization line probe assay to detect HPV infection, and immunohistochemical staining for p16INK4A and Ki67, we analysed 26 penile squamous cell carcinomas (SCCs) and 20 independent penile lichen sclerosus (LS) lesions from 46 patients. Results, HPV DNA was found in 54% of penile SCCs and 33% of penile LS cases in single and multiple infections. High-risk HPV 16 was the predominant HPV type detected. No relationship between Ki67 expression and HPV infection was observed. Strong immunostaining for p16INK4A correlated with HPV 16/18 infection in both penile LS and penile SCC. In our penile SCC series the cancer margins were also associated with penile LS in 13 of 26 lesions, and HPV was detected in seven of the 13 SCC cases associated with LS and in six of the 11 SCC lesions not involving LS. Conclusions, Our study shows a high prevalence of HPV 16 and p16INK4A expression in penile lesions, consistent with an active role for HPV in interfering with the retinoblastoma pathway. High-risk HPV infection could be involved in the tumorigenic process in 50% of penile cancers, and the use of prophylactic HPV vaccines has the potential to prevent these cancers. [source] Hypermethylation of FHIT as a prognostic marker in nonsmall cell lung carcinomaCANCER, Issue 7 2004Riichiroh Maruyama M.D. Abstract BACKGROUND Methylation of CpG islands in the promoter and upstream coding regions has been identified as a mechanism for transcriptional inactivation of tumor suppressor genes. The purpose of the current study was to determine the correlation between the aberrant promoter methylation of multiple genes and survival in patients with nonsmall cell lung carcinoma (NSCLC). METHODS The methylation status of nine genes was determined in 124 surgically resected NSCLC cases using methylation-specific polymerase chain reaction. RESULTS The methylation frequencies of the genes tested in NSCLC specimens were 52% for E-cadherin (CDH1), 41% for RAS association domain family protein (RASSF1A), 38% for fragile histidine triad (FHIT) and adenomatous polyposis coli (APC), 27% for retinoic acid receptor beta (RAR,) and H-cadherin (CDH13), 20% for p16INK4A, 0.8% for O6 -methylguanine-DNA-methyltransferase (MGMT), and 0% for glutathione S-transferase P1 (GSTP1). The survival of the patients with FHIT methylation-positive tumors was found to be significantly shorter than that for those patients with methylation-negative tumors (P = 0.03), even in those patients with International Union Against Cancer TNM Stage I or Stage II disease (P = 0.007). In contrast, there were no significant survival differences noted between the methylation-positive and methylation-negative tumors for the other genes tested. In addition, based on multivariate analyses, FHIT methylation-positive status was found to be independently associated with poor survival (P = 0.046) and disease stage (P < 0.0001). CONCLUSIONS The results of the current study suggest that methylation of FHIT is a useful biomarker of biologically aggressive disease in patients with NSCLC. Cancer 2004;100:1472,7. © 2004 American Cancer Society. [source] Definition of three minimal deleted regions by comprehensive allelotyping and mutational screening of FHIT,p16INK4A, and p19ARF genes in nasopharyngeal carcinomaCANCER, Issue 7 2002Jenq-Yuh Ko M.D. Abstract BACKGROUND Recurrent deletion on a chromosomal location in tumor cells can be detected by frequent allelic loss and generally is considered to be an indication of the existence of a tumor suppressor gene (TSG) in the region. In the current study, using fluorescent-labeled, high-density microsatellite markers for allelotyping, the authors pinpointed three minimal deleted regions (MDRs) and screened mutations of putative TSGs on chromosomes 3, 9, and 11 in nasopharyngeal carcinoma (NPC) cases occurring in Taiwan. METHODS A total of 133 informative microsatellite markers were used on chromosomes 3, 9, and 11 with an average marker density of 4 centimorgans (cM) for the allelotyping of genomic DNAs isolated from NPC tissues and their corresponding lymphocytes in 48 patients. The correlation between allelic loss and the clinicopathologic parameters of NPC tissues was examined. In addition, putative TSGs including FHIT, p16INK4a, and p19ARF were selected for mutation screening to investigate their potential participation in NPC tumorigenesis. RESULTS Of 3787 informative allelotyping data, 25 frequent allelic losses (or loss of heterozygosity [LOH]) in 13 cytogenetic loci were identified based on a deletion frequency that was greater than the average of allelic loss on that particular chromosome. Several significant associations were determined after statistical analysis of the correlation between allelic loss and clinicopathologic parameters. The allelic losses by D9S318 and D11S1304 were associated with N2/N3 (P = 0.035 and P = 0.005, respectively), and those by D9S905 and D11S1304 were associated with grouped American Joint Committee on Cancer (AJCC) Stage III/IV samples (P = 0.022 and P = 0.017, respectively) of NPC tissues. In addition, three MDRs were revealed on 3p25.3-24.1 (< 19 cM), 3p23-21.31 (< 9 cM), and 11q22.1-23.2 (< 8 cM). To examine somatic mutations in previously reported TSGs located near these frequent LOH loci, three candidate genes, p16INK4a, p19ARF, and FHIT, were analyzed. Point mutations in the coding region of FHIT and in the intron 1 splicing acceptor site of both p16INK4a and p19ARF were detected in NPC cell lines. Sequence analysis of both p16INK4a and p19ARF transcripts revealed that the point mutation resulted in skipping of exon 2 and the generation of shorter transcripts. CONCLUSIONS High-density allelotyping permitted the discovery of 3 MDRs on 3p25.3-24.1 (< 19 cM), 3p23-21.31 (< 9 cM), and 11q22.1-23.2 (< 8 cM) and a correlation was determined between allelic loss and clinicopathologic parameters of NPC tissues. More important, one somatic mutation in NPC cell lines on the intron 1/exon 2 splicing acceptor site of the INK4a/ARF locus was found to result in exon 2 skipping both p16INK4a and p19ARF transcripts, which presumably inactivates the functions of both the p16INK4a and p19ARF proteins. Cancer 2002;94:1987,96. © 2002 American Cancer Society. DOI 10.1002/cncr.10406 [source] Human ovarian surface epithelial cells immortalized with hTERT maintain functional pRb and p53 expressionCELL PROLIFERATION, Issue 5 2007N. F. Li Normal human ovarian surface epithelial (OSE) cells, which are thought to be the origin of most of human ovarian carcinomas, have a very limited lifespan in culture. Establishment of immortalized OSE cell lines has, in the past, required inactivation of pRb and p53 functions. However, this often leads to increased chromosome instability during prolonged culture. Materials and Methods:,In this study, we have used a retroviral infection method to overexpress human telomerase reverse transcriptase (hTERT) gene, in primary normal OSE cells, under optimized culture conditions. Results:,In vitro and in vivo analysis of hTERT-immortalized cell lines confirmed their normal epithelial characteristics. Gene expression profiles and functional analysis of p16INK4A, p15INK4B, pRb and p53 confirmed the presence of their intact functions. Our study suggests that inactivation of pRb and p53 is not necessary for OSE immortalization. Furthermore, down-regulation of p15INK4B in the immortalized cells may indicate a functional role for this protein in them. Conclusion:,These immortal OSE cell lines are likely to be an important tool for studying human OSE biology and carcinogenesis. [source] Human Papillomavirus and Overexpression of P16INK4a in Nonmelanoma Skin CancerDERMATOLOGIC SURGERY, Issue 3 2004Ingo Nindl PhD Background. P16INK4a overexpression has been identified as a specific biomarker in high-risk human papillomavirus (HPV),infected cervical (pre)cancer lesions. Objective. To evaluate the overexpression of this cyclin-dependent kinase inhibitor in skin tumors depending on HPV infections, we analyzed normal skin, benign skin disease, and skin cancer specimens. Methods. Biopsies of 23 patients with normal histology (3), psoriasis (2), verrucae vulgaris (2), actinic keratoses (5), squamous cell carcinoma (SCC) in situ (3), Bowen's carcinoma (1), and SCC (7) were analyzed. Specimens of 23 patients were immunostained using the monoclonal antibody E6H4 specific for p16INK4a. HPV status was assessed by a polymerase chain reaction (PCR) system to detect all currently known HPV types. MY (MY09/MY11 and MYN9/MYN10)-, CP (CP65/CP70 and CP66/CP69)-nested PCR, and three single PCR methods CN1, CN3, and CN4 were used in a first step, and HPV typing was performed by restriction fragment length polymorphism analysis. Only ,-globin,positive patients were included in this study. Results. HPV DNA was detected in all actinic keratoses, SCC in situ, Bowen's carcinoma, and SCC, in 50% (one of two) of verrucae vulgaris, in 66% (two of three) of normal skin, and in none of two psoriasis. P16INK4a expression was not detected in normal skin, psoriasis, and verrucae vulgares. Overexpression of p16INK4a was detected in a subset of dysplastic cells (10% to 80%) of all skin (pre)cancer lesions such as actinic keratoses, SCC in situ, Bowen's carcinoma, and SCC infected with HPV independent of sun exposure. Conclusion. P16INK4a appears to be overexpressed in a portion of dysplastic cells from actinic keratoses and SCC. Further studies to examine the association of HPV infection and the overexpression of p16INK4a are warranted. [source] The use of p16INK4A immunocytochemistry in "Atypical squamous cells which cannot exclude HSIL" compared with "Atypical squamous cells of undetermined significance" in liquid-based cervical smearsDIAGNOSTIC CYTOPATHOLOGY, Issue 3 2010Chang Ohk Sung M.D. Abstract Even though p16INK4a (p16) immunocytochemistry has proven a useful accessory tool verifying the identification of atypical squamous cells of undetermined significance (ASC-US) categorized smears, the procedure still has limitations. To date few studies examining the usefulness of p16 immunocytochemistry in atypical squamous cells which cannot exclude HSIL (ASC-H), compared with ASC-US in liquid-based cervical smears. Therefore, we examined the correlation of p16 immunocytochemical staining with follow-up biopsy results on ASC-H categorized smears and compared the data with those classified as ASC-US on 105 liquid-based cytology samples. We found no statistical significance in the p16 expression of ASC-US smears and the presence of squamous intraepithelial lesions (SIL) in follow-up biopsies (p = 0.546). However, p16 expression did significantly correlate with the presence of SIL (p = 0.002) in ASC-H smears. There was a statistically significant relationship between p16 expression and presence of high grade squamous intraepithelial lesions (HSIL) or more on the follow-up biopsies in both ASC-US (p = 0.012) and ASC-H (p < 0.001) categorized smears. In ASC-US categorized smears, there was no statistical significance between p16 expression and the HR-HPV viral load (p = 0.091). But there was a statistical significance between p16 expression and the HR-HPV viral load (p < 0.001) in ASC-H categorized smears. Our results indicate that p16 immunostaining is a much better useful marker for HR-HPV infection and detection of SIL in ASC-H categorized smears compared to those defined as ASC-US. Diagn. Cytopathol. 2010. © 2009 Wiley-Liss, Inc. [source] Are adjunctive markers useful in routine cervical cancer screening?DIAGNOSTIC CYTOPATHOLOGY, Issue 7 2008Application of p16INK4a, HPV-PCR on ThinPrep samples with histological follow-up Abstract The objectives of the study were to evaluate 1) the diagnostic sensitivity and specificity of p16INK4a as a marker for high-grade cervical lesions, 2) the results of a real-time polymerase chain reaction detecting high-risk human papillomavirus, and 3) the interobserver variability of the p16INK4a interpretation. A total of 232 ThinPrep samples were stained for p16INK4a, and HPV-DNA PCR was performed on 107 specimens with inclusion of both benign and abnormal cytology. Histological follow-up information was collected. The diagnostic sensitivity of ASC+ with CIN2+ in histology as endpoint was 96% for p16INK4a and 100% for HR-HPV DNA PCR, and the diagnostic specificity was 41% and 27%, respectively. If p16INK4a had been used for triage of the ASC samples, then 18 patients (42%) could have been spared unnecessary follow-up procedures compared to six patients (21%) with the HR-HPV DNA test. Diagn. Cytopathol. 2008;36:453,459. © 2008 Wiley-Liss, Inc. [source] Comparison of p16INK4A and Hybrid Capture® 2 human papillomavirus testing as adjunctive tests in liquid-based gynecologic SurePathÔ preparationsDIAGNOSTIC CYTOPATHOLOGY, Issue 3 2008Aziza Nassar M.D., F.I.A.C. Abstract p16INK4a, cyclin-dependent kinase inhibitor, is functionally inactivated in many tumors, including cervical cancer. We compared p16INK4A immunocytochemical staining and Hybrid Capture® 2 (HCII) on SurePathÔ specimens using tissue biopsies (as the gold standard). Their utility in a spectrum of atypical and preneoplastic lesions, and their ability to accurately identify underlying lesions of CIN II or greater was assessed using biopsy follow-up data. One-hundred and seventeen residual SurePathÔ samples were collected: 43 atypical squamous cells of undetermined significance (ASCUS), 47 low-grade (LGSIL), and 27 high-grade (HGSIL) squamous intraepithelial lesions. Two slides were prepared from each sample; one stained with the SurePathÔ autocyte stain and one immunostained using the CINtecÔ p16INK4a Cytology Kit (Dakocytomation). High-risk HPV testing was performed using the HCII DNA test (Digene, Gaithersburg, MD). Available tissue biopsy follow-up data was retrieved. p16INK4a was positive in 32.6% (14/43) ASCUS, 46.8% (22/47) LGSIL, and 48.1% (13/27) HGSIL specimens. HCII DNA test was positive in 41.9% (18/43) ASCUS, 78.7% (37/47) LGSIL, and 96.3% (26/27) HGSIL samples. The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values of p16INK4a and HCII were: 58.7% and 89.8%, 58.6% and 34.6%, 69.2% and 72.1%, 47.2% and 64.3%, respectively. In patients with cervical biopsies, the PPV of HCII (92.3%) results for a biopsy with CINII/III was significantly higher than the PPV of p16INK4a (52%) (P = 0.001). Using liquid-based cytology specimens, HCII is a more sensitive test than p16INK4a for detection of abnormal cytology. HCII has a higher PPV than p16INK4a for identifying CIN II/III. Diagn. Cytopathol. 2008;36:142,148. © 2008 Wiley-Liss, Inc. [source] Differential DNA methylation associated with hepatitis B virus infection in hepatocellular carcinomaINTERNATIONAL JOURNAL OF CANCER, Issue 6 2007Pei-Fen Su Abstract Gene inactivation through DNA hypermethylation plays a pivotal role in carcinogenesis. This study aimed to profile aberrant DNA methylation in different stages of liver disease, namely noncirrhosis, cirrhosis and hepatocellular carcinoma (HCC), and also to clarify the influence of hepatitis B virus (HBV) infection on the aberrant DNA methylation in HCCs. Promoter methylation in p14ARF, p16INK4a, O6 -methylguanine-DNA methyltransferase (MGMT), glutathione S -transferase pi (GSTP1) and E-cadherin (E-Cad) genes of 58 HCCs paired with adjacent nontumorous tissues was assayed by methylation-specific PCR. HBV infection was determined using a hepatitis B virus surface antigen (HBsAg) serological assay. The frequency of p16INK4a promoter methylation increased from noncirrhotic, cirrhotic, to HCC tissues (noncirrhotic vs. HCC, p < 0.001), while that of GSTP1 promoter methylation increased in cirrhotic tissues compared to noncirrhotic ones (p = 0.029). The frequency of GSTP1 promoter hypermethylation is significantly higher in HCC than in nontumorous tissues (p = 0.022) from HBsAg-positive patients, but not the HBsAg-negative controls (p = 0.289). While the frequency of E-Cad promoter hypermethylation remained high in both nontumorous tissues and HCCs from HBsAg-positive patients (p = 0.438), it was lower in HCCs than in nontumorous tissues from HBsAg-negative patients (p = 0.002). In contrast, the frequency of p16INK4a, MGMT and p14ARF promoter hypermethylation in HCCs was unrelated to HBsAg status. In conclusion, aberrant DNA methylation may begin at different stages of liver disease in a gene-dependent manner. Moreover, HBV infection may enhance or maintain GSTP1 and E-Cad promoter methylation and thereby affect hepatocarcinogenesis. © 2007 Wiley-Liss, Inc. [source] Immunocytochemistry in liquid-based cervical cytology: Analysis of clinical use following a cross-sectional studyINTERNATIONAL JOURNAL OF CANCER, Issue 5 2006Shaira Sahebali Abstract Cytological screening for cervical cancer is hampered by imperfect sensitivity and low inter-observer reproducibility. Human papillomavirus (HPV) testing lacks specificity as a primary screening method. Studies indicate that immunocytochemical detection of alterations caused by HPV in the host cells can optimise screening. Here, the potential of p16INK4a (cyclin-dependent kinase inhibitor p16) and MIB-1 (Ki-67 proliferation marker) as adjunct molecular markers for cervical lesions was investigated in a prospective, cross-sectional study of 500 samples in the framework of opportunistic screening in Flanders, Belgium. A consecutive series of 200 samples and 100 samples from the cytological categories ASC, LSIL and HSIL were investigated. Surepath samples were interpreted according to the Bethesda 2001 reporting system. HPV testing was done with MY09/MY11 consensus PCR. Immunocytochemistry for p16INK4a and MIB-1 was performed with an automated staining protocol. The number of immunoreactive cells/1,000 cervical cells was assessed. There was a higher mean number of p16INK4A and MIB-1 immunoreactive cells/1,000 cells in HSIL (4.06 ± 1.93 and 11.13 ± 2.83, respectively) compared to other cytological categories. Both markers showed a large spread in counts, for all categories. In cases of HSIL without immunoreactive cells for either marker, low cellularity and long-term storage in water were often the cause of false negativity. This study confirms that positive staining for p16INK4a and MIB-1 is highly correlated with presence of high-grade lesions. These markers could be used as adjuncts to increase the sensitivity of cytological screening as well as the specificity of the HPV test. However, clear methodological standards are needed for optimal performance of immunocytochemistry in a clinical setting. © 2005 Wiley-Liss, Inc. [source] DNA methylation patterns in adenomas from FAP, multiple adenoma and sporadic colorectal carcinoma patientsINTERNATIONAL JOURNAL OF CANCER, Issue 4 2006Coral V.A. Wynter Abstract Colorectal adenomas have traditionally been regarded as homogeneous. The aim of our study was to identify molecular features that may differentiate sporadic adenomas from familial adenomas such as Familial Adenomatous Polyposis (FAP) and Multiple Adenoma patients. DNA methylation was tested at Methylated IN Tumor (MINT) loci (1,2,12,31) and the CpG promoter region of genes MLH1, HPP1, MGMT, p14ARF and p16INK4a in FAP-associated adenomas (33) from 5 patients with a known APC mutation (Group 1, FAP), adenomas (29) from 4 Multiple Adenoma patients (Group 2 Multiple), adenomas (14) from 3 patients with sporadic colorectal cancers showing high microsatellite instability (Group 3, MSI-H) and adenomas (16) from 7 patients, with sporadic colorectal cancers showing microsatellite stable or low level instability (Group 4, MSS/MSI-L). Aberrant Crypt Foci (ACFs), Hyperplastic Polyps (HPs) and cancers were also examined for methylation status as well as K- ras mutation. Multiple Adenoma patients were examined for germline polymorphisms in the base excision repair gene, MYH. The familial syndrome, FAP -associated adenomas showed a significantly low frequency of MINT methylation (15.5%,) compared to sporadic MSS/MSI-L-associated adenomas (35.5%). Group 3 (MSI-H) adenomas were different in that many showed serration and a high level of methylation (57.1%). Group 2, Multiple Adenoma cases, resembled sporadic MSS/MSI-L-associated adenomas. However the promoter regions of key genes, MGMT, p14ARF and p16INK4a were methylated to a greater extent than MINTs in both sporadic and familial adenomas. Genetic profiling of adenomas supports the concept that adenomas belonging to familial syndromes pursue a different pathway to tumorigenesis than their sporadic counterpar/ts from their earliest formation. © 2005 Wiley-Liss, Inc. [source] The melanoma-associated 24 base pair duplication in p16INK4a is functionally impairedINTERNATIONAL JOURNAL OF CANCER, Issue 4 2005Therese M. Becker Abstract Melanoma-associated germline mutations affecting the tumor suppressor and cyclin-dependent kinase (CDK) inhibitor, CDKN2A/p16INK4a, have been identified in over 100 melanoma-prone families worldwide. To predict the melanoma risk for carriers of specific mutations, mutant p16INK4a can be tested in biochemical and cellular assays. In most cases, p16INK4a mutations with predicted disease relation, due to segregation with melanoma, are functionally impaired in such assays. The N-terminal 24 base pair duplication of CDKN2A, however, encodes a p16INK4a variant previously shown to have wild-type function, despite segregating with melanoma in at least 5 melanoma families. To clarify whether the duplication mutation has a cell cycle regulatory defect or behaves like wild-type p16INK4a, we reanalyzed the cell cycle-inhibitory activity of this mutation. Stable cell clones of the p16-null WMM1175 melanoma cell line inducible for ectopic p16INK4a were used in this study. In these cells, p16INK4a expression can be controlled at physiologic levels. Our results show that in comparison to wild-type p16INK4a, the duplication mutant induced weaker S-phase inhibition and cells expressing this mutant form of p16INK4a retained colony formation ability. We also show that the cell cycle-regulatory defect of the p16INK4a duplication mutant was associated with decreased inhibition of pRb phosphorylation even though it retained significant binding to CDK4. © 2005 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||