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Tumour Suppressor Gene (tumour + suppressor_gene)
Selected AbstractsThe taurine transporter: mechanisms of regulationACTA PHYSIOLOGICA, Issue 1-2 2006X. Han Abstract Taurine transport undergoes an adaptive response to changes in taurine availability. Unlike most amino acids, taurine is not metabolized or incorporated into protein but remains free in the intracellular water. Most amino acids are reabsorbed at rates of 98,99%, but reabsorption of taurine may range from 40% to 99.5%. Factors that influence taurine accumulation include ionic environment, electrochemical charge, and post-translational and transcriptional factors. Among these are protein kinase C (PKC) activation and transactivation or repression by proto-oncogenes such as WT1, c-Jun, c-Myb and p53. Renal adaptive regulation of the taurine transporter (TauT) was studied in vivo and in vitro. Site-directed mutagenesis and the oocyte expression system were used to study post-translational regulation of the TauT by PKC. Reporter genes and Northern and Western blots were used to study transcriptional regulation of the taurine transporter gene (TauT). We demonstrated that (i) the body pool of taurine is controlled through renal adaptive regulation of TauT in response to taurine availability; (ii) ionic environment, electrochemical charge, pH, and developmental ontogeny influence renal taurine accumulation; (iii) the fourth segment of TauT is involved in the gating of taurine across the cell membrane, which is controlled by PKC phosphorylation of serine 322 at the post-translational level; (iv) expression of TauT is repressed by the p53 tumour suppressor gene and is transactivated by proto-oncogenes such as WT1, c-Jun, and c-Myb; and (v) over-expression of TauT protects renal cells from cisplatin-induced nephrotoxicity. [source] RNAi knockdown of the focal adhesion protein TES reveals its role in actin stress fibre organisationCYTOSKELETON, Issue 3 2005Elen Griffith Abstract TES was originally identified as a candidate tumour suppressor gene and has subsequently been found to encode a novel focal adhesion protein. As well as localising to cell-matrix adhesions, TES localises to cell-cell contacts and to actin stress fibres. TES interacts with a variety of cytoskeletal proteins including zyxin, mena, VASP, talin and actin. There is evidence that TES may function in actin-dependent processes as overexpression of TES results in increased cell spreading and decreased cell motility. Together with TES's interacting partners, these data suggest that TES might be involved in regulation of the actin cytoskeleton. Here, for the first time, we have used RNAi to successfully knockdown TES in HeLa cells and we demonstrate that loss of TES from focal adhesions results in loss of actin stress fibres. Similarly, and as previously reported, RNAi-mediated knockdown of zyxin results in loss of actin stress fibres. TES siRNA treated cells show reduced RhoA activity, suggesting that the Rho GTPase pathway may be involved in the TES RNAi-induced loss of stress fibres. We have also used RNAi to examine the requirement of TES and zyxin for each other's localisation at focal adhesions, and we propose a hierarchy of recruitment, with zyxin being first, followed by VASP and then TES. Cell Motil. Cytoskeleton 60:140,152, 2005. © 2005 Wiley-Liss, Inc. [source] Prognostic value of p27kip1 expression in adenocarcinoma of the pancreatic head regionHPB, Issue 3 2006Jerzy Mielko Abstract Background. p27kip1 is a tumour suppressor gene, functioning as a cyclin-dependent kinase inhibitor, and an independent prognostic factor in breast, colon, and prostate adenocarcinomas. Conflicting data are reported for adenocarcinoma of the pancreas. The aim of this study was to establish the prognostic value of p27kip1 expression in adenocarcinoma of the pancreatic head region. Patients and methods. The study included 45 patients (male/female ratio 2:1; mean age 59, range 38,82 years) with adenocarcinomas of the pancreatic head region: 24 , pancreatic head, 18 , periampullary and 3 , uncinate process. The patients underwent the Kausch-Whipple pancreatoduodenectomy (n=39), pylorus-preserving pancreatoduodenectomy (n=5), or nearly total pancreatectomy (n=1). Eight patients received adjuvant chemotherapy postoperatively. Follow-up time ranged from 3 to 60 months. Tumours were staged according to the pTNM classification (UICC 1997). Immunohistochemistry was done on paraffin-embedded blocks from tumour sections. Quantitative determination of p27kip1 expression was based on the proportion of p27kip1 -positive cells (< 5%= negative). Survival analysis was carried out using the Kaplan-Meier method and Cox regression model. Results. Positive p27kip1 expression was detected in 22 tumours (49%), whereas 23 tumours (51%) were p27kip1 -negative. There were no significant correlations between p27kip1 index and stage or lymph node involvement. Median survival time in patients with p27kip1 -positive tumours was 19 months, whereas in patients with p27kip1 -negative tumours it was 18 months (p=0.53). A significant relationship was found between p27kip1 -negative tumours and radical resection (p=0.04). Multivariate survival analysis revealed that the localization of the tumour (pancreatic head/uncinate process vs periampullary) was the only significant and independent prognosticator (p=0.01, Cox regression model). Resection margins involvement and grade remained nearly significant prognostic factors (p=0.07 and p=0.09, respectively). Conclusion. We conclude that p27kip1 has limited overall prognostic utility in resected carcinoma of the pancreatic head region, but its potential role as a marker of residual disease needs to be further assessed. [source] TP53 mutation signature supports involvement of aristolochic acid in the aetiology of endemic nephropathy-associated tumoursINTERNATIONAL JOURNAL OF CANCER, Issue 4 2009Tatiana Nedelko Abstract The proposal has been put forward that the primary cause of Balkan endemic nephropathy (BEN) is exposure to food crops contaminated with seeds of Aristolochia spp, which contain high levels of aristolochic acids (AA). Recently, tumour DNA samples from patients with BEN were found to harbour principally A to T mutations in the TP53 tumour suppressor gene (Grollman et al., Proc Natl Acad Sci USA 2007;104:12129,34). Using a novel mutation assay in which we can induce and select mutations in human TP53 sequences in vitro by exposure of cultured cells to a mutagen, we found that A to T mutations were elicited by aristolochic acid at sites in TP53 rarely mutated in human cancers in general, but which were observed in the BEN patients. This concordance of specific mutations in patient tumours and aristolochic acid I-exposed cultures supports the argument that AA has a direct role in the aetiology of BEN-associated cancer. © 2008 Wiley-Liss, Inc. [source] No relationship observed between human p53 codon-72 genotype and HPV-associated cervical cancer in a population group with a low arginine-72 allele frequencyINTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 3 2007V. A. Govan Summary Infection with high-risk human papillomavirus (HR-HPV) is a necessary but not a sufficient event in the development of cervical cancer, as most infections regress without intervention. Thus, genetic host factors and cellular immune responses could be potential modifiers for the risk of developing cervical cancer. In particular, p53 is considered as the most critical tumour suppressor gene and is involved in regulating cell division. The polymorphism on p53, which encodes either a proline or an arginine amino acid residue at codon 72, has been reported as a possible risk factor for cervical disease. This polymorphism has been shown to differentially affect the efficiency of degradation of p53 protein mediated by HR-HPV E6 oncoprotein. Women with histologically proven cancer of the cervix (n = 111) and hospital-based controls (n = 143) were included in this study. The patients and controls were from the Western Cape Province in South Africa. Genotyping of the p53 polymorphism was conducted using polymerase chain reaction and restriction fragment-length polymorphism method. The distributions of the allelic frequencies were stratified in both patients and controls into two South African ethnic population groups. In this study, we observed no association between the distribution of p53 polymorphism and susceptibility to cervical cancer in the Western Cape Province populations (P = 0.466). However, the frequency of the Pro/Pro residue at codon 72 was increased in the South African population when compared to Caucasians, Indians and Portuguese population groups. Notably, as the distribution of the Pro/Pro at codon 72 of p53 gene was significantly different (P < 0.05) between the control groups of South Africa and other population groups. This result suggests that ethnic disparity may influence the levels of p53 produced. [source] The p53 molecule and its prognostic role in squamous cell carcinomas of the head and neckJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 9 2000Karin Nylander Abstract: Despite intense research, the 5-year survival rate for patients with squamous cell carcinoma of the head and neck (SCCHN) is still low. Several different factors have been studied in the search for one or more factors that give important prognostic information at the time of diagnosis. Many recent studies have focused on the TP53 tumour suppressor gene, analysing its gene status and protein status. When looking at p53 protein expression, using immunohistochemistry, no correlation to patient outcome has been seen for the whole group of SCCHN. However, a significant association between p53 expression and poor patient outcome was found when looking only at patients with laryngeal squamous cell carcinomas. Also, in oral premalignant lesions, expression of p53-positive cells in the suprabasal layers of the epithelium has been seen as an indication of impending malignant development. Concerning the prognostic significance of mutations in the TP53 gene, results differ. But when restricting analysis to tumours with mutations causing an obvious change in protein, TP53 mutation was found to be a strong and independent variable for prognosticating survival. This review article gives an up-to-date overview of the p53 molecule and evaluates its possible prognostic role in SCCHN. Today it is clear that the p53 pathway is very important in SCCHN biology and potentially in its treatment. The function and importance of a few other cell cycle proteins connected to p53 are also discussed. [source] Global DNA methylation in fetal human germ cells and germ cell tumours: association with differentiation and cisplatin resistance,THE JOURNAL OF PATHOLOGY, Issue 4 2010Hendrik Wermann Abstract Differences in the global methylation pattern, ie hyper- as well as hypo-methylation, are observed in cancers including germ cell tumours (GCTs). Related to their precursor cells, GCT methylation status differs according to histology. We investigated the methylation pattern of normal fetal, infantile, and adult germ cells (n = 103) and GCTs (n = 251) by immunohistochemical staining for 5- cytidine. The global methylation pattern of male germ cells changes from hypomethylation to hypermethylation, whereas female germ cells remain unmethylated at all stages. Undifferentiated GCTs (seminomas, intratubular germ cell neoplasia unclassified, and gonadoblastomas) are hypomethylated, whereas more differentiated GCTs (teratomas, yolk sac tumours, and choriocarcinomas) show a higher degree of methylation. Embryonal carcinomas show an intermediate pattern. Resistance to cisplatin was assessed in the seminomatous cell line TCam-2 before and after demethylation using 5-azacytidine. Exposure to 5-azacytidine resulted in decreased resistance to cisplatin. Furthermore, after demethylation, the stem cell markers NANOG and POU5F1 (OCT3/4), as well as the germ cell-specific marker VASA, showed increased expression. Following treatment with 5-azacytidine, TCam-2 cells were analysed using a high-throughput methylation screen for changes in the methylation sites of 14 000 genes. Among the genes revealing changes, interesting targets were identified: ie demethylation of KLF11, a putative tumour suppressor gene, and hypermethylation of CFLAR, a gene previously described in treatment resistance in GCTs. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Suppression of putative tumour suppressor gene GLTSCR2 expression in human glioblastomas,THE JOURNAL OF PATHOLOGY, Issue 2 2008Y-J Kim Abstract Glioma tumour-suppressor candidate region gene 2 (GLTSCR2/PICT-1) is localized within the well-known 1.4 Mb tumour-suppressive region of chromosome 19q, which is frequently altered in various human tumours, including diffuse gliomas. Aside from its chromosomal localization, several lines of evidence, including PTEN-phosphorylating and cell-killing activities, suggests that GLTSCR2 participates in the suppression of tumour growth and development. However, little is known about the biological functions and molecular mechanisms of GLTSCR2 as a tumour suppressor gene. We investigated the pathological significance of GLTSCR2 expression in association with the development and progression of glioblastomas, the most common malignant brain tumour. We used real-time PCR and western blot analysis to examine the expression levels of GLTSCR2 mRNA and protein in glioblastomas, normal brain tissue and in non-glial tumour tissue of different origin, and found that GLTSCR2 expression is down-regulated in glioblastomas. In addition, direct sequencing analysis and fluorescence in situ hybridization clearly demonstrates the presence of genetic alterations, such as a nonsense mutation and deletion, in the GLTSCR2 gene in glioblastomas. Finally, our immunohistochemical study demonstrates that GLTSCR2 is sequentially down-regulated according to the histological malignant progression of the astrocytic glial tumour. Taken together, our results suggest that GLTSCR2 is involved in astrocytic glioma progression. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Discriminating functional and non-functional p53 in human tumours by p53 and MDM2 immunohistochemistryTHE JOURNAL OF PATHOLOGY, Issue 3 2005R Nenutil Abstract Mutation and/or loss of the TP53 tumour suppressor gene is the single most common genetic abnormality in human cancer. The majority of TP53 mutations lead to stabilization of the protein, so that immunohistochemical staining for p53 can suggest mutation status in many cases. However, various false-positive and false-negative situations mean that simple immunostaining for p53 is not informative in a substantial number of tumours. In the present study, a series of 119 human cancers were immunostained using a highly sensitive technique that detects the low levels of wild-type protein expressed in normal cells, such that homozygous gene deletion or non-sense TP53 mutation can be identified by an absence of staining. TP53 gene status was also assessed using FASAY as a genetic/functional screen and in selected cases by direct sequencing. A quantitative scoring system was employed to assess p53 levels, and p53 post-translational modification was evaluated using antibodies that detect specific phosphorylation sites. Phosphorylated p53 correlated with total p53 levels and did not improve the prediction of TP53 mutation status. The transcriptional activity of TP53 was determined by staining for two downstream target genes, p21WAF1 and MDM2, and statistical correlations between MDM2/p21WAF1 and p53 were found in tumours with wild-type, but not mutant TP53. Measurement of staining for p53 and MDM2 accurately identifies the TP53 status of tumours. This simple and cost-effective method, applicable to automated staining and quantitation methods, improves the identification of TP53 status over standard methods for p53 immunostaining and provides information about tumour p53 phenotype that is complementary to genotyping data. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Long-term infection with Helicobacter felis and inactivation of the tumour suppressor gene p53 cumulatively enhance the gastric mutation frequency in Big Blue® transgenic miceTHE JOURNAL OF PATHOLOGY, Issue 4 2003Peter J Jenks Abstract The aims of this study were to determine whether colonization with Helicobacter felis resulted in the accumulation of mutations within murine gastric tissue and whether the degree of genetic damage was increased by p53 deficiency. Female C57BL/6 mice carrying either the lambda/lacI transgene (Big Blue® transgenic mice) or the lambda/lacI transgene and deficient in one allele of the p53 tumour suppressor gene (TSG-p53®/Big Blue®) were inoculated with H felis. Seven months after inoculation, mutations in the target lacI gene were assessed using the Big Blue® transgenic mutagenesis assay system in these animals and in controls. There was an approximately two-fold increase in lacI mutations in gastric mucosa harvested from mice infected with H felis and also from non-infected mice heterozygous for the p53 allele relative to wild-type mice. The mutation frequency in mice infected with H felis and deficient in one allele of p53 was increased approximately three-fold. Active gastric inflammation was significantly greater in H felis -infected p53 hemizygous mice compared with H felis p53 wild-type mice. Gastric epithelial proliferation was similarly increased with infection in both of these latter groups of mice. In infected mice, there was a significant correlation between the mutation frequency and the degree of active gastric inflammation. These data suggest a synergistic action between infection with H felis and p53 deficiency in the accumulation of mutations within gastric tissue. Active neutrophil infiltration in gastric Helicobacter infection may contribute to the increased levels of mutation observed. Copyright © 2003 John Wiley & Sons, Ltd. [source] Association of p53 polymorphism with ICSI/IVF failure and recurrent pregnancy lossAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 2 2009FIROUZABADI Razieh Dehghani Background: The p53 tumour suppressor gene is a well-known factor regulating apoptosis in a wide variety of cells. Alterations in the p53 gene are among the most common genetic changes in human cancers. Several polymorphisms of the p53 tumour suppressor gene have been associated with recurrent pregnancy loss (RPL). Aims: To evaluate the association of polymorphisms p53 codon 72 with the response to in vitro fertilisation (IVF) treatment and occurrence of repeated miscarriages. Methods: The homozygous and heterozygous genotypes and allelic frequencies of Arg and Pro p53 at codon 72 were identified by using polymerase chain reaction,restriction fragment length polymorphism technique in 70 infertile women with more than two IVF failures. Each comparison was made with 97 women experiencing RPL and 32 fertile women each with at least two healthy children as the control group. Results: The frequency of homozygous Pro/Pro genotypes was found significantly higher among the women with RPL than the other two groups (P = 0.041). Whereas, Arg/Arg genotype was significantly different in the recurrent implantation failure (RIF) group (P = 0.005). Conclusion: It is concluded that p53 codon 72 polymorphism may serve as a susceptible factor affecting the chances of RPL and RIF. [source] The H19 locus: Role of an imprinted non-coding RNA in growth and developmentBIOESSAYS, Issue 6 2010Anne Gabory Abstract The H19 gene produces a non-coding RNA, which is abundantly expressed during embryonic development and down-regulated after birth. Although this gene was discovered over 20 years ago, its function has remained unclear. Only recently a role was identified for the non-coding RNA and/or its microRNA partner, first as a tumour suppressor gene in mice, then as a trans-regulator of a group of co-expressed genes belonging to the imprinted gene network that is likely to control foetal and early postnatal growth in mice. The mechanisms underlying this transcriptional or post-transcriptional regulation remain to be discovered, perhaps by identifying the protein partners of the full-length H19 RNA or the targets of the microRNA. This first in vivo evidence of a functional role for the H19 locus provides new insights into how genomic imprinting helps to control embryonic growth. [source] Inactivation of the CDKN2A and the p53 tumour suppressor genes in external genital carcinomas and their precursorsBRITISH JOURNAL OF DERMATOLOGY, Issue 3 2007N. Soufir Summary Background, p53 has been extensively studied in external genital carcinoma (EGC), and is frequently inactivated, but little is known about the role of the CDKN2A tumour suppressor gene in the oncogenesis of EGC. Objectives, To investigate the role of CDKN2A and p53 in the pathogenesis of EGCs and their precursor lesions vulval intraepithelial neoplasia (VIN3), penile intraepithelial neoplasia and lichen sclerosus (LS). Methods, By means of CDKN2A and p53 mutation screening (single-strand conformational polymorphism analysis and sequencing), methylation analysis of alternative CDKN2A promoters (methylation-specific polymerase chain reaction) and p53 immununochemistry, we analysed eight invasive EGCs (five from vulva and three from penis) and 25 precancerous lesions (two undifferentiated VIN3 and 23 vulval/penile lesions of LS) from 33 patients. Results, p53 mutations (mainly transversions) and CDKN2A mutations (including one hot spot) were present in 75% and 50% of invasive tumours, respectively, but were absent in all precancerous lesions. Remarkably, all CDKN2A -mutated tumours also harboured a p53 mutation. CDKN2A or p53 mutations were observed more frequently in LS-derived EGCs than in human papillomavirus-derived EGCs (P = 0·053). A positive anti-p53 staining, but without p53 mutations, was also detected in 30% of LS lesions, suggesting a p53 stabilization in response to inflammation and carcinogenic insult. Methylation of p16INK4a and p14ARF promoters was not a frequent mechanism of CDKN2A inactivation. Conclusions, Our study shows a high prevalence of co-inactivating mutations of p53 and/or CDKN2A genes in EGC, that seem to occur preferentially in LS-derived tumours and late in oncogenesis. [source] Identification of transcripts modulated by ETV6 expressionBRITISH JOURNAL OF HAEMATOLOGY, Issue 1 2007Gino Boily Summary Deletions at chromosome 12p12-13 are observed in 26,47% of childhood pre-B acute lymphoblastic leukaemia (ALL) cases, suggesting the presence of a tumour suppressor gene (TSG). Accumulating genetic and functional evidence points to ETV6 as being the most probable TSG targeted by the deletions. ETV6 is a ubiquitously expressed transcription factor of the ETS family with very few known targets. To understand its function and to elucidate the impact of its absence in leukaemia, we conducted a study to identify targeted genes. Following the induction of ETV6 expression, global expression was evaluated at different time points. We identified 87 modulated genes, of which 10 (AKR1C1, AKR1C3, IL18, LUM, PHLDA1, PTGER4, PTGS2, SPHK1, TP53 and VEGF) were validated by real-time quantitative reverse transcription-polymerase chain reaction. To assess the significance of the validated candidate genes in leukaemia, their expression patterns were determined, as well as that of ETV6, in pre-B ALL patients. The expression of IL18, LUM, PTGER4, SPHK1 and TP53 was significantly correlated with that of ETV6, further suggesting that ETV6 could regulate the expression of these genes in leukaemia. This work constitutes another step towards the understanding of the functions of ETV6 and the impact of its inactivation in childhood leukaemia. [source] Characterization of the insulin-like growth factor axis and Wilms' tumour suppressor gene in hyperparathyroidism ,BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 10 2007C. K. M. Wong Background: Genetic mutations and upregulation of growth factors are implicated in the pathogenesis of hyperparathyroidism. The aim of this study was to evaluate the role of Wilms' tumour suppressor gene (WT-1) and the insulin-like growth factor (IGF) axis in hyperparathyroidism. Methods: The expression of WT-1 and IGF components was examined by immunohistochemistry, reverse transcriptase,polymerase chain reaction and western immunoblotting in a panel of parathyroid specimens from both primary and secondary hyperparathyroidism. A human parathyroid cell culture model was established to examine the parathyroid response to IGF stimulation. Results: There was a significantly lower level of WT-1 expression in parathyroid tumours than in normal parathyroid glands. Most tumours expressed IGF-I and IGF-II receptors and responded to IGF stimulation. Only IGF-I was present in normal parathyroid glands, whereas IGF-II was expressed exclusively in parathyroid tumours. Conclusion: Abnormal expression of WT-1 and the IGF axis may play a role in the pathogenesis of hyperparathyroidism. Copyright © 2007 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] Heparin regulates colon cancer cell growth through p38 mitogen-activated protein kinase signallingCELL PROLIFERATION, Issue 1 2010G. Chatzinikolaou Objectives:, Heparin acts as an extracellular stimulus capable of activating major cell signalling pathways. Thus, we examined the putative mechanisms utilized by heparin to stimulate HT29, SW1116 and HCT116 colon cancer cell growth. Materials and methods:, Possible participation of the mitogen-activated protein kinase (MAPK) cascade on heparin-induced HT29, SW1116 and HCT116 colon cancer cell growth was evaluated using specific MAPK cascade inhibitors, Western blot analysis, real-time quantitative PCR and FACS apoptosis analysis. Results:, Treatment with a highly specific p38 kinase inhibitor, SB203580, significantly (50,70%) inhibited heparin-induced colon cancer cell growth, demonstrating that p38 MAPK signalling is involved in their heparin-induced proliferative response. This was shown to be correlated with increased (up to 3-fold) phosphorylation of 181/182 threonine/tyrosine residues on p38 MAP kinase. Furthermore, heparin inhibited cyclin-dependent kinase inhibitor p21WAF1/CIP1 and p53 tumour suppressor gene and protein expression up to 2-fold or 1.8-fold, respectively, and stimulated cyclin D1 expression up to 1.8-fold, in these cell lines through a p38-mediated mechanism. On the other hand, treatment with heparin did not appear to affect HT29, SW1116 and HCT116 cell levels of apoptosis. Conclusions:, This study demonstrates that an extracellular glycosaminoglycan, heparin, finely modulates expression of genes crucial to cell cycle regulation through specific activation of p38 MAP kinase to stimulate colon cancer cell growth. [source] The ESCRT machinery is not required for human cytomegalovirus envelopmentCELLULAR MICROBIOLOGY, Issue 12 2007Alberto Fraile-Ramos Summary The human cytomegalovirus (HCMV) has been proposed to complete its final envelopment on cytoplasmic membranes prior to its release to the extracellular medium. The nature of these membranes and the mechanisms involved in virus envelopment and release are poorly understood. Here we show by immunogold-labelling and electron microscopy that CD63, a marker of multivesicular bodies (MVBs), is incorporated into the viral envelope, supporting the notion that HCMV uses endocytic membranes for its envelopment. We therefore investigated a possible role for the cellular endosomal sorting complex required for transport (ESCRT) machinery in HCMV envelopment. Depletion of tumour suppressor gene 101 and ALIX/AIP1 with small interfering RNAs (siRNAs) in HCMV-infected cells did not affect virus production. In contrast, siRNAs against the vacuolar protein sorting 4 (VPS4) proteins silenced the expression of VPS4A and VPS4B, inhibited the sorting of epidermal growth factor to lysosomes, the formation of HIV Gag-derived virus-like particles and vesicular stomatitis virus infection, but enhanced the number of HCMV viral particles produced. Treatment of infected cells with protease inhibitors also increased viral production. These studies indicate that, in contrast to some enveloped RNA viruses, HCMV does not require the cellular ESCRT machinery to complete its envelopment. [source] Multiple cutaneous and uterine leiomyomata resulting from missense mutations in the fumarate hydratase geneCLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 1 2006G. S. Chuang Summary Multiple cutaneous and uterine leiomyomata (MCL) is an autosomal dominant disorder characterized by the development of benign smooth muscle tumours (leiomyomas) in the skin and uterus of affected women, and in the skin of affected men. In rare cases, MCL has been associated with a predisposition to the rare type II papillary renal cell cancer, also known as hereditary leiomyomatosis and renal cell cancer. The genetic locus for MCL has been mapped to chromosome 1q42.3,43 and subsequently, germline mutations in the fumarate hydratase (FH) gene have been identified. In addition, analysis of FH in some tumours of MCL patients revealed a second mutation inactivating the wild-type allele, suggesting that FH may function as a tumour suppressor gene. Here, we report two cases of MCL patients with FH mutations, designated as T287P and R190L. T287P represents a novel mutation of a highly conserved amino acid of the FH protein. In addition, a patient with an unusual clinical presentation of MCL was found to have the recurrent mutation, R190L, raising the possibility of incorporating FH sequencing as a diagnostic tool. Our findings extend the allelic series of mutations in FH and support its status as the underlying cause of MCL. [source] Novel MEN1 germline mutations in Brazilian families with multiple endocrine neoplasia type 1CLINICAL ENDOCRINOLOGY, Issue 3 2007Rodrigo A. Toledo Summary Objective, To characterize clinical features and identify MEN1 germline mutations in Brazilian families with multiple endocrine neoplasia type 1 (MEN1). Settings, Non-profit academic centre. Patients, Fourteen Brazilian families with MEN1 and 141 at-risk relatives. Results, We identified 12 different MEN1 disease-causing mutations, seven of them previously unreported: 308delC; 375del21; 549A>T (I147F); 1243delA; 1348T>G (L413R); 1351T>C (L414P) and 1523G>T (W471C). Families with the recurrent mutations 360delTCTA and L413R were shown to be unrelated by mitochondrial-DNA and Y-chromosome haplotype analyses. Most of the MEN1 single point mutations involved evolutionarily conserved residues, whereas most of the deletion/frameshift changes occurred in GC-rich repetitive regions. Genetic screening of 141 at-risk family members identified 38 MEN1 mutation carriers, 37 (97·4%) of whom had at least one major MEN1-related tumour upon clinical investigation. Conclusions, High frequencies of MEN1 gene mutations were detected in Brazilian families with MEN1, including seven new genetic mutations that are predicted to cause inactivation of the MEN1 tumour suppressor gene. Our data underscore the need to implement a systematic MEN1 screening programme in Brazil. [source] Systemic therapy for metastatic malignant melanoma , from deeply disappointing to bright future?EXPERIMENTAL DERMATOLOGY, Issue 5 2008Paul Lorigan Abstract:, The last decade has seen a considerable improvement in the understanding of the biology of melanoma. Advances have come in the understanding of the importance of critical oncogenes and tumour suppressor genes, epigenetic phenomena, signalling pathways, drug resistance mechanisms, the pivotal role of the local immune system, and the importance of cell,cell and cell,matrix interactions. Many of these pathways and interactions include potentially ,drugable' targets. These developments have allowed the identification and/or design of a range of new, targeted therapies. Evaluation of these new drugs has brought a whole new series of challenges. These include indentification of appropriate pre-clinical models, overcoming the redundancy inbuilt in complex biological systems, identification of appropriate molecular and clinical endpoints to show that the drug is hitting the target, how to combine treatments, and new toxicities. For the first time, there is the possibility of personalised treatment for melanoma patients, based on individual host and tumour characteristics. This paper discusses the range of new drugs and targets have been identified, the outcome of clinical trials, and the directions for future advances. [source] Hypermethylation of gene promoters in hematological neoplasiaHEMATOLOGICAL ONCOLOGY, Issue 4 2002C. S. Chim Abstract Cancer cells are associated with global hypomethylation but with focal hypermethylation of specific gene promoters organized as CpG island. DNA methyltransferases, DNMT1 and 3 (3a and 3b), have been implicated in mediating maintenance and de novo methylation. Hypermethylation of gene promoters results in the inactivation of the corresponding genes, by preclusion of the formation of the transcription complex, due to the recruitment of MBP, MeCPs and histone deacetylase. This results in the deacetylation of histone and thus a compact chromatin complex unfavourable for the initiation of transcription. This methylation-associated gene silencing has been demonstrated in various genes including tumour suppressor genes (p15, p16, p73, VHL). Therefore, gene promoter hypermethylation collaborates with other mechanisms of gene inactivation such as deletion and intragenic mutations to fulfil Knudson's hypothesis. Hypermethylation may serve as a molecular disease marker for the detection of minimal residual disease. Emerging evidence suggests a possible prognostic value of gene promoter hypermethylation. Moreover, gene hypermethylation may also serve as a target for therapeutic invention by hypomethylating agents. Copyright © 2002 John Wiley & Sons, Ltd. [source] Poorly differentiated transitional cell carcinoma versus leiomyosarcoma of the ureter: different defects in tumour suppressor genesHISTOPATHOLOGY, Issue 2 2007C Y Tzen No abstract is available for this article. [source] Changes in retinoblastoma gene expression during cervical cancer progressionINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 6 2002Mauricio Salcedo Summary. The role of tumour suppressor genes in the development of human cancers has been studied extensively. In viral carcinogenesis, the inactivation of suppressor proteins such as retinoblastoma (pRb) and p53, and cellular oncogenes overexpression, such as c-myc, has been the subject of a number of investigations. In uterine-cervix carcinomas, where high-risk human papillomavirus (HPV) plays an important role, pRb and p53 are inactivated by E7 and E6 viral oncoproteins, respectively. However, little is known about the in situ expression of some of these proteins in pre-malignant and malignant cervical tissues. On the other hand, it has also been demonstrated that c-myc is involved in cervical carcinogenesis, and that pRb participates in the control of c-myc gene expression. By using immunostaining techniques, we investigated pRb immunodetection pattern in normal tissues, squamous intraepithelial lesions (SILs) and invasive carcinomas from the uterine cervix. Our data show low pRb detection in both normal cervical tissue and invasive lesions, but a higher expression in SILs. C-Myc protein was observed in most of the cellular nuclei of the invasive lesions, while in SILs was low. These findings indicate a heterogeneous pRb immunostaining during the different stages of cervical carcinogenesis, and suggest that this staining pattern could be a common feature implicated in the pathogenesis of uterine-cervix carcinoma. [source] Reduced expression and novel splice variants of ING4 in human gastric adenocarcinoma,THE JOURNAL OF PATHOLOGY, Issue 1 2009Ming Li Abstract ING4, a new member of the ING (inhibitor of growth) family of tumour suppressor genes, has been found to be deleted or down-regulated in gliomas, breast tumours, and head and neck squamous cell carcinomas. The goal of the present study was to investigate whether the expression and alternative splicing of ING4 transcripts are involved in the initiation and progression of stomach adenocarcinoma. ING4 mRNA and protein expression was examined in gastric adenocarcinoma tissues and human gastric adenocarcinoma cell lines by RT-PCR, real-time RT-PCR, tissue microarray immunohistochemistry, and western blot analysis. Alterations in ING4 transcripts were determined through sequence analysis of ING4 cDNA. Our data showed that ING4 mRNA and protein were dramatically reduced in stomach adenocarcinoma cell lines and tissues, and significantly less in female than in male patients. We also found that reduced ING4 mRNA expression correlated with the stage of the tumour. Interestingly, by sequence analysis, we discovered five novel aberrantly spliced variant forms of ING4_v1 and ING4_v2. These variants cause a codon frame-shift and, eventually, deletion of the NLS or PHD domain contributing to the mislocalization of p53 and/or HAT/HDAC complexes and, subsequently, altered gene expression in gastric adenocarcinoma. These results suggest that attenuated and aberrant ING4 expression may be involved in the initiation and progression of stomach adenocarcinoma. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Distinct promoter hypermethylation of p16INK4a, CDH1, and RAR-beta in intestinal, diffuse,adherent, and diffuse,scattered type gastric carcinomasTHE JOURNAL OF PATHOLOGY, Issue 1 2002Naohide Oue Abstract Hypermethylation of CpG islands in gene promoters is associated with silencing of various tumour suppressor genes. Recent studies of colorectal and gastric carcinomas have defined a CpG island methylator phenotype (CIMP), which involves the targeting of multiple genes by promoter hypermethylation. In this study, methylation-specific polymerase chain reaction (PCR) was performed to study methylation of CpG islands in the promoters of the p16INK4a, cadherin 1 (CDH1), and retinoic acid receptor-beta (RAR-beta) genes in 45 gastric carcinomas and to investigate whether CDH1 and RAR-beta promoter hypermethylation is associated with CIMP-positive gastric carcinoma. CpG island hypermethylation of the p16INK4a, CDH1, and RAR-beta promoters was detected in 12 (27%), 26 (58%), and 24 (53%) of the 45 gastric carcinomas, respectively. Hypermethylation of the p16INK4a promoter was more common in intestinal type than in diffuse type gastric carcinomas (p = 0.0023; Fisher's exact test) and was inversely associated with p53 mutations (p = 0.0225; Fisher's exact test). However, CDH1 and RAR-beta promoter hypermethylation was observed more frequently in diffuse,scattered type gastric carcinoma than in other types (intestinal and diffuse,adherent types) (p = 0.0175 and p = 0.0335, respectively; Fisher's exact test) and was not associated with p53 mutation status. Moreover, hypermethylation of the CDH1 and RAR-beta promoters occurred concordantly (p < 0.0001; Fisher's exact test). These results suggest that at least two types of promoter methylation status are involved in the development of the intestinal (p16INK4a promoter hypermethylation) and diffuse,scattered types (CDH1 and RAR-beta promoter hypermethylation) of gastric carcinoma. Copyright © 2002 John Wiley & Sons, Ltd. [source] HP24 MICRORNA EXPRESSION PROFILES IN BARRETT'S OESOPHAGUSANZ JOURNAL OF SURGERY, Issue 2007D. I. Watson Purpose The genetic changes that drive the metaplastic change from squamous oesophagus (NO) towards Barrett's oesophagus (BO) and cancer are unclear. microRNAs (miRNAs) are short, non-coding RNAs that regulate gene expression and contribute to cellular differentiation and identity. We sought to determine the role of miRNAs in BO. Methodology Biopsies of NO, BO and cardia were taken from 7 patients and RNA was extracted. miRNA expression profiles of 300 miRNAs were determined by microarray. Guided by the array results, real-time Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) for 8 selected miRNAs enabled their expression to be studied in tissues from another 15 patients. Results Array data revealed that 39 miRNAs were significantly differentially expressed between NO, BO and cardia. A tissue-specific expression profile was confirmed by RT-PCR, with miR-21, 143, 145, 194 and 215 significantly up regulated in BO and cardia (columnar) vs. NO (squamous). A trend towards increased miR-21 expression from NO to BO and adenocarcinoma was observed (p = 0.1). Interestingly, high expression of miR-143, 194 and 215 was seen in BO vs. NO (p < 0.0001), but with subsequent downregulation in cancers (p = 0.1). In contrast, miR-203 and 205 were highly expressed in NO and low in BO and cardia. A database search revealed that these miRNAs potentially target (proto-)oncogenes and tumour suppressor genes. Conclusions Differences in miRNA expression are present between NO, BO, cardia and cancer. Deregulation of certain miRNAs, and their predicted effect on the expression of target genes, might contribute to the metaplastic and neoplastic process in the oesophagus and could serve as novel biomarkers to classify diseased tissues. [source] The roles of microRNA in cancer and apoptosisBIOLOGICAL REVIEWS, Issue 1 2009Niamh Lynam-Lennon Abstract microRNAs (miRNAs) are highly conserved, non-protein-coding RNAs that function to regulate gene expression. In mammals this regulation is primarily carried out by repression of translation. miRNAs play important roles in homeostatic processes such as development, cell proliferation and cell death. Recently the dysregulation of miRNAs has been linked to cancer initiation and progression, indicating that miRNAs may play roles as tumour suppressor genes or oncogenes. The role of miRNAs in apoptosis is not fully understood, however, evidence is mounting that miRNAs are important in this process. The dysregulation of miRNAs involved in apoptosis may provide a mechanism for cancer development and resistance to cancer therapy. This review examines the biosynthesis of miRNA, the mechanisms of miRNA target regulation and the involvement of miRNAs in the initiation and progression of human cancer. It will include miRNAs involved in apoptosis, specifically those miRNAs involved in the regulation of apoptotic pathways and tumour suppressor/oncogene networks. It will also consider emerging evidence supporting a role for miRNAs in modulating sensitivity to anti-cancer therapy. [source] Establishment and characterization of seven human renal cell carcinoma cell linesBJU INTERNATIONAL, Issue 1 2000K.-H. Shin Objective,To establish human renal cell carcinoma (RCC) cell lines, and to investigate the cell phenotypes and molecular characteristics of human RCC cell lines and their corresponding tumour tissues. Materials and methods,Seven human RCC cell lines from pathologically proven RCCs were established. The histopathology of the primary tumours, in vitro growth characteristics and status of tumour suppressor genes, mismatch repair genes and microsatellite instability (MSI) were examined in cell lines and their corresponding tumour tissues. Five of the cell lines were derived from clear cells (SNU-228, -267, -328, -349, and -1272), one from granular cells (SNU-482), and one from mixed clear and granular cell types (SNU-333). The mutational status was compared for von Hippel-Lindau (VHL), p53, TGF-, type II receptor (TGF-,RII), hMSH2, and hMLH1 genes in the cell lines and their corresponding tumour tissues. The MSI status of the cell lines was determined by screening for adenine repeat sequences, e.g. BAT-25, BAT-26, and BAT-40. Results,All lines showed different doubling times and were confirmed by DNA fingerprinting analysis to be unique. Contamination by mycoplasma or bacteria was excluded. In two cell lines (SNU-349 and -1272) and their tumour tissues, mutations in the VHL gene were found. The SNU-267 line had a frameshift mutation in the p53 gene. A missense mutation of the TGF-,RII gene was detected in the SNU-1272 line and the corresponding tissue. Analysis of the repeat sequences showed one cell line (SNU-349) to have MSI and the other six to have microsatellite stability. As MSI is a hallmark of the inactivation of mismatch repair genes, the presence of hMSH2 and hMLH1 mutations was investigated in all seven cell lines. An inactivating homozygous single base-pair deletion of the hMLH1 gene was found only in the SNU-349 cell line and corresponding tissue. Moreover, a frameshift mutation within an 8-bp polyadenine repeat present in the hMSH3 coding region was found only in the MSI cell line and tumour tissue. Conclusion,These newly established RCC cell lines should provide a useful in vitro model for studies related to human RCC. The SNU-349 cell line should be especially useful for studies of MSI and mismatch repair-defective RCCs. [source] Microarray analysis of aberrant gene expression in actinic keratosis: effect of the Toll-like receptor-7 agonist imiquimodBRITISH JOURNAL OF DERMATOLOGY, Issue 6 2007A. Torres Summary Background, The molecular events leading to actinic keratosis (AK) are not well understood. Objective, To identify and compare gene expression changes in AK lesions and in sun-exposed nonlesional skin and to determine the effect of imiquimod 5% cream on these changes. Method, A double-blind, vehicle-controlled, randomized study was conducted to evaluate the molecular changes in AK treated with imiquimod. Seventeen male subjects with , 5 AK lesions on the scalp applied vehicle or imiquimod three times a week for 4 weeks. Gene expression analysis using Affymetrix® oligonucleotide arrays was performed on shave biopsies of lesions taken before and after treatment. Confocal microscopy was performed on the study area as an adjunctive diagnostic procedure. Results, We identified gene expression changes which occur in sun-exposed, nonlesional skin as well as in AK lesions. These changes include, but are not limited to, the overexpression of oncogenic and proliferative genes and diminished expression of tumour suppressor genes. The gene expression changes observed in AK lesions and in sun-exposed, nonlesional skin were consistent with the confocal microscopy observations, which showed abnormalities in the sun-exposed, nonlesional skin, similar in nature but less pronounced than abnormalities seen in AK. Imiquimod partially or totally reversed the aberrant expression of some of the genes observed in AK, consistent with clearing of lesions and normalization of confocal cellular images. Conclusions, The data show that profound gene expression changes occur in sun-exposed, nonlesional skin which progress further in AK lesions. The data also suggest that imiquimod may play a role in normalizing gene expression and cellular morphology in sun-damaged skin. [source] Inactivation of the CDKN2A and the p53 tumour suppressor genes in external genital carcinomas and their precursorsBRITISH JOURNAL OF DERMATOLOGY, Issue 3 2007N. Soufir Summary Background, p53 has been extensively studied in external genital carcinoma (EGC), and is frequently inactivated, but little is known about the role of the CDKN2A tumour suppressor gene in the oncogenesis of EGC. Objectives, To investigate the role of CDKN2A and p53 in the pathogenesis of EGCs and their precursor lesions vulval intraepithelial neoplasia (VIN3), penile intraepithelial neoplasia and lichen sclerosus (LS). Methods, By means of CDKN2A and p53 mutation screening (single-strand conformational polymorphism analysis and sequencing), methylation analysis of alternative CDKN2A promoters (methylation-specific polymerase chain reaction) and p53 immununochemistry, we analysed eight invasive EGCs (five from vulva and three from penis) and 25 precancerous lesions (two undifferentiated VIN3 and 23 vulval/penile lesions of LS) from 33 patients. Results, p53 mutations (mainly transversions) and CDKN2A mutations (including one hot spot) were present in 75% and 50% of invasive tumours, respectively, but were absent in all precancerous lesions. Remarkably, all CDKN2A -mutated tumours also harboured a p53 mutation. CDKN2A or p53 mutations were observed more frequently in LS-derived EGCs than in human papillomavirus-derived EGCs (P = 0·053). A positive anti-p53 staining, but without p53 mutations, was also detected in 30% of LS lesions, suggesting a p53 stabilization in response to inflammation and carcinogenic insult. Methylation of p16INK4a and p14ARF promoters was not a frequent mechanism of CDKN2A inactivation. Conclusions, Our study shows a high prevalence of co-inactivating mutations of p53 and/or CDKN2A genes in EGC, that seem to occur preferentially in LS-derived tumours and late in oncogenesis. [source] | ||||||||||||||||||||||||||||||||||