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Various Tumors (various + tumor)
Terms modified by Various Tumors Selected AbstractsImmune response modifiers , mode of actionEXPERIMENTAL DERMATOLOGY, Issue 5 2006Meinhard Schiller Abstract:, The innate immune system governs the interconnecting pathways of microbial recognition, inflammation, microbial clearance, and cell death. A family of evolutionarily conserved receptors, known as the Toll-like receptors (TLRs), is crucial in early host defense against invading pathogens. Upon TLR stimulation, nuclear factor-,B activation and the interferon (IFN)-regulatory factor 3 pathway initiate production of pro-inflammatory cytokines, such as interleukin-1 and tumor necrosis factor-,, and production of type I IFNs (IFN-, and IFN-,), respectively. The innate immunity thereby offers diverse targets for highly selective therapeutics, such as small molecular synthetic compounds that modify innate immune responses. The notion that activation of the innate immune system is a prerequisite for the induction of acquired immunity raised interest in these immune response modifiers as potential therapeutics for viral infections and various tumors. A scenario of dermal events following skin cancer treatment with imiquimod presumably comprises (i) an initial low amount of pro-inflammatory cytokine secretion by macrophages and dermal dendritic cells (DCs), thereby (ii) attracting an increasing number type I IFN-producing plasmacytoid DCs (pDCs) from the blood; (iii) Langerhans cells migrate into draining lymph nodes, leading to an increased presentation of tumor antigen in the draining lymph node, and (iv) consequently an increased generation of tumor-specific T cells and finally (v) an accumulation of tumoricidal effector cells in the treated skin area. The induction of predominately T helper (Th)1-type cytokine profiles by TLR agonists such as imiquimod might have further benefits by shifting the dominant Th2-type response in atopic diseases such as asthma and atopic dermatitis to a more potent Th1 response. [source] Multiple genomic alterations on 21q22 predict various TMPRSS2/ERG fusion transcripts in human prostate cancersGENES, CHROMOSOMES AND CANCER, Issue 11 2007Wennuan Liu A number of TMPRSS2/ERG fusion transcripts have been reported since the discovery that recurrent genomic rearrangements result in the fusion of TMPRSS2 and ETS family member genes. In this article we present evidence demonstrating that multiple genomic alterations contribute to the formation of various TMPRSS2/ERG transcripts. Using allele-specific analysis of the data generated from the GeneChip 500K SNP array we observed both hemizygous and homozygous deletions occurring at different locations between and within TMPRSS2 and ERG in prostate cancers. The 500K SNP array enabled us to fine map the start and end of each deletion to specific introns of these two genes, and to predict a variety of fusion transcripts, including a new form which was confirmed by sequence analysis of the fusion transcripts in various tumors. We also inferred that translocation is an additional mechanism of fusion for these two genes in some tumors, based on largely diploid genomic DNA between TMPRSS and ERG, and different fusion transcripts produced in these tumors. Using a bioinformatics approach, we then uncovered the consensus sequences in the regions harboring the breakpoints of the deletions. These consensus sequences were homologous to the human Alu-Sq and Alu-Sp subfamily consensus sequences, with more than 80% homology. The presence/absence of Alu family consensus sequence in the introns of TMPRSS2 and ERG correlates with the presence/absence of fusion transcripts of theses two genes, indicating that these consensus sequences may contribute to genomic deletions and the fusion of TMPRSS2 and ERG in prostate cancer. © 2007 Wiley-Liss, Inc. [source] Mitochondrial DNA mutations and mitochondrial DNA depletion in breast cancerGENES, CHROMOSOMES AND CANCER, Issue 7 2006Ling-Ming Tseng Somatic mutations in mitochondrial DNA (mtDNA) have been demonstrated in various tumors, including breast cancer. However, it still remains unclear whether the alterations in mtDNA are related to the clinicopathological features and/or the prognosis in the breast cancer. We analyzed somatic mutations in the D-loop region, the common 4,977-bp deletion, and the copy number of mtDNA in breast cancer and paired nontumorous breast tissues from 60 Taiwanese patients. We found that 18 of the 60 (30%) breast cancers displayed somatic mutations in mtDNA D-loop region. The incidence of the 4,977-bp deletion in nontumorous breast tissues (47%) was much higher than that in breast cancers (5%). The copy number of mtDNA was significantly decreased in 38 of the 60 (63%) breast cancers as compared to their corresponding nontumorous breast tissues (P = 0.0008). The occurrence of D-loop mutations was associated with an older onset age (,50 years old, P = 0.042), and tumors that lacked expressions of estrogen receptor and progesterone receptor (P = 0.024). Patients with mtDNA D-loop mutation and breast cancer had significantly poorer disease-free survival than those without mutation, when assessed by Kaplan,Meier curves and log-rank test (P = 0.005). Multivariate Cox regression analysis indicated that a D-loop mutation is a significant marker that is independent of other clinical variables and that it can be used to assess the prognosis of patients. Our findings suggest that somatic mutations in mtDNA D-loop can be used as a new molecular prognostic indicator in breast cancer. © 2006 Wiley-Liss, Inc. [source] Upregulated claudin-1 expression confers resistance to cell death of nasopharyngeal carcinoma cellsINTERNATIONAL JOURNAL OF CANCER, Issue 6 2010Jeng-Woei Lee Abstract Accumulating evidence reveals that aberrant expression of claudins manifests in various tumors; however, their biological functions are poorly understood. Here, we report on the elevated expression of claudin-1 in nasopharyngeal carcinoma (NPC) cell lines under serum deprivation or fluorouracil (5-FU) treatment. Interestingly, an increase in expression of claudin-1 considerably reduced apoptosis rather than enhancing cell proliferation. However, claudin-1 expression and activity were unaffected by external stimuli or Akt and NF-,B activation. Notably, predominant cytoplasmic and nuclear localization of claudin-1 in NPC cells reflected the aforementioned feature. On the other hand, loss of epithelial morphology and E-cadherin expression was associated with serum withdrawal in NPC cells. Interestingly, restoration of E-cadherin inhibited the protein elevation and antiapoptotic activity of claudin-1. In conclusion, our data demonstrate the regulation and novel biological function of claudin-1 and indicate the important role of claudin-1 in NPC tumorigenesis. [source] Targeting the epidermal growth factor receptor by erlotinib (TarcevaÔ) for the treatment of esophageal cancerINTERNATIONAL JOURNAL OF CANCER, Issue 7 2006Andreas P. Sutter Abstract Esophageal cancer is the sixth most common cause of cancer-related death worldwide. Because of very poor 5-year survival new therapeutic approaches are mandatory. Erlotinib (TarcevaÔ), an inhibitor of epidermal growth factor receptor tyrosine kinase (EGFR-TK), potently suppresses the growth of various tumors but its effect on esophageal carcinoma, known to express EGFR, remains unexplored. We therefore studied the antineoplastic potency of erlotinib in human esophageal cancer cells. Erlotinib induced growth inhibition of the human esophageal squamous cell carcinoma (ESCC) cell lines Kyse-30, Kyse-70 and Kyse-140, and the esophageal adenocarcinoma cell line OE-33, as well as of primary cell cultures of human esophageal cancers. Combining erlotinib with the EGFR-receptor antibody cetuximab, the insulin-like growth factor receptor tyrosine kinase inhibitor tyrphostin AG1024, or the 3-hydroxy-3-methylglutaryl coenzyme. A reductase (HMG-CoAR) inhibitor fluvastatin resulted in additive or even synergistic antiproliferative effects. Erlotinib induced cell cycle arrest at the G1/S checkpoint. The erlotinib-mediated signaling involved the inactivation of EGFR-TK and ERK1/2, the upregulation of the cyclin-dependent kinase inhibitors p21Waf1/CIP1 and p27Kip1, and the downregulation of the cell cycle promoter cyclin D1. However, erlotinib did not induce immediate cytotoxicity or apoptosis in esophageal cancer cells. The inhibition of EGFR-TK by erlotinib appears to be a promising novel approach for innovative treatment strategies of esophageal cancer, as it powerfully induced growth inhibition and cell cycle arrest in human esophageal cancer cells and enhanced the antineoplastic effects of other targeted agents. © 2005 Wiley-Liss, Inc. [source] High throughput functional genomics: Identification of novel genes with tumor suppressor phenotypesINTERNATIONAL JOURNAL OF CANCER, Issue 3 2005Kerstin Koenig-Hoffmann Abstract We have used a combination of high throughput functional genomics, computerized database mining and expression analyses to discover novel human tumor suppressor genes (TSGs). A genome-wide high throughput cDNA phenotype screen was established to identify genes that induce apoptosis or reduce cell viability. TSGs are expressed in normal tissue and frequently act by reduction of growth of transformed cells or induce apoptosis. In agreement with that and thus serving as platform validation, our pro-apoptotic hits included genes for which tumor suppressing activities were known, such as kangai1 and CD81 antigen. Additional genes that so far have been claimed as putative TSGs or associated with tumor inhibitory activities (prostate differentiation factor, hRAS-like suppressor 3, DPH2L1-like and the metastasis inhibitor Kiss1) were confirmed in their proposed TSG-like phenotype by functionally defining their growth inhibitory or pro-apoptotic function towards cancer cells. Finally, novel genes were identified for which neither association with cell growth nor with apoptosis were previously described. A subset of these genes show characteristics of TSGs because they (i) reduce the growth or induce apoptosis in tumor cells; (ii) show reduced expression in tumor vs. normal tissue; and (iii) are located on chromosomal (LOH-) loci for which cancer-associated deletions are described. The pro-apoptotic phenotype and differential expression of these genes in normal and malignant tissue make them promising target candidates for the diagnosis and therapy of various tumors. [source] Inhibition of constitutive activity of nuclear transcription factor kappaB sensitizes doxorubicin-resistant cells to apoptosisJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2009Charitha Gangadharan Abstract Doxorubicin is one of the most effective agents used in the treatment of various tumors. Its use is restricted by the development of resistance to apoptosis, the mechanism of which is not fully understood. Nuclear transcription factor kappaB (NF-,B) has been shown both to block apoptosis and to promote cell proliferation, and hence has been considered as an important target for anticancer drug development. We found that in wild type and Dox-revertant MCF-7 cells, Doxorubicin induced NF-,B was transient and Dox-resistant cells showed high basal activity of NF-,B and expression of genes dependent on it. Moreover, in resistant cells Doxorubicin was unable to induce apoptosis as detected by assays for reactive oxygen intermediates generation, lipid peroxidation, cytotoxicity, PARP degradation and Bcl-2 expression. High basal expressions of multi-drug resistant protein and transglutaminase were found in Dox-resistant cells and inhibition of NF-,B decreased those amounts and also sensitized these cells by Doxorubicin. These observations collectively suggest that high NF-,B activity confers resistance to Doxorubicin and its inhibition potentiates apoptosis. This study indicates that NF-,B plays an important role in chemoresistance and establishes the fact that inhibition of NF-,B will be a novel approach in chemotherapy. J. Cell. Biochem. 107: 203,213, 2009. © 2009 Wiley-Liss, Inc. [source] Green tea extracts decrease carcinogen-induced mammary tumor burden in rats and rate of breast cancer cell proliferation in cultureJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2001Kathryn T. Kavanagh Abstract Epidemiological evidence suggests tea (Camellia sinensis L.) has chemopreventive effects against various tumors. Green tea contains many polyphenols, including epigallocatechin-3 gallate (EGCG), which possess anti-oxidant qualities. Reduction of chemically induced mammary gland carcinogenesis by green tea in a carcinogen-induced rat model has been suggested previously, but the results reported were not statistically significant. Here we have tested the effects of green tea on mammary tumorigenesis using the 7,12-dimethylbenz(a)anthracene (DMBA) Sprague-Dawley (S-D) rat model. We report that green tea significantly increased mean latency to first tumor, and reduced tumor burden and number of invasive tumors per tumor-bearing animal; although, it did not affect tumor number in the female rats. Furthermore, we show that proliferation and/or viability of cultured Hs578T and MDA-MB-231 estrogen receptor-negative breast cancer cell lines was reduced by EGCG treatment. Similar negative effects on proliferation were observed with the DMBA-transformed D3-1 cell line. Growth inhibition of Hs578T cells correlated with induction of p27Kip1 cyclin-dependent kinase inhibitor (CKI) expression. Hs578T cells expressing elevated levels of p27Kip1 protein due to stable ectopic expression displayed increased G1 arrest. Thus, green tea had significant chemopreventive effects on carcinogen-induced mammary tumorigenesis in female S-D rats. In culture, inhibition of human breast cancer cell proliferation by EGCG was mediated in part via induction of the p27Kip1 CKI. J. Cell. Biochem. 82:387,398, 2001. © 2001 Wiley-Liss, Inc. [source] Concordant overexpression of phosphorylated ATF2 and STAT3 in extramammary Paget's diseaseJOURNAL OF CUTANEOUS PATHOLOGY, Issue 4 2009Si-Yuan Chen Background:, Activating transcription factor 2 (ATF2) and signal transducer and activator of transcription 3 (STAT3) play important roles in the pathogenesis of various tumors, but ATF2 expression/activation and the relationship with STAT3 activation have not yet been investigated in extramammary Paget's disease (EMPD). Objective:, To investigate potential contributions of ATF2 and STAT3 pathways to the pathogenesis of EMPD. Method:, Paraffin-embedded 45 EMPD specimens (43 primary EMPD and 2 nodal metastases) were subjected to immunohistochemical staining for ATF2, phosphorylated (p)-ATF2 and p-STAT3. Results:, P-ATF2 expression in advanced EMPD, non-invasive EMPD and normal skin (NS) controls were 97.9 ± 1.8%, 82.0 ± 23.4% and 45.8 ± 3.2%, respectively, and p-STAT3 expression in advanced EMPD, non-invasive EMPD and NS were 97.0 ± 2.9%, 83.2 ± 23.3% and 50.1 ± 6.7%, respectively. P-ATF2 and p-STAT3 expressions in EMPD were significantly higher than those in NS, indicating a possible contribution of these pathways to the tumor development. P-ATF2 and p-STAT3 expressions in advanced EMPD were significantly higher than those in non-invasive EMPD, possibly indicating that these pathways might also contribute to the tumor invasion and/or metastasis. We also found an exceptionally high positive correlation between p-ATF2 and p-STAT3 expressions in EMPD. Conclusions:, P-ATF2 and p-STAT3 are concordantly overexpressed in EMPD and their expressions may possibly be associated with the tumor stage. [source] Differential, stage-dependent expression of Hsp70, Hsp110 and Bcl-2 in colorectal cancerJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 6 2003TAE SOOK HWANG Abstract Background: The presence of hypoxic cells in solid tumors has been suggested to contribute to the malignant progression of various tumors. Recently, we reported an activation of heat shock transcription factor (HSF) and expression of heat shock proteins (Hsp) in murine tumor cells by hypoxia. Methods: To search for a possible role of Hsp in the malignant progression of human tumors, we analyzed the expression profiles of Hsp family proteins in weakly and highly metastatic human colorectal cancer (CRC) cell lines. We also analyzed the expression profiles of Bcl-2 family proteins because the altered expression of these proteins has been demonstrated in various solid tumors. Results: In the present paper we showed among various Hsp and Bcl-2 family proteins that the expression of Hsp70 and Hsp110 was elevated in highly metastatic CX-1 and HT-29 cells, while the expression of Bcl-2 was elevated in weakly metastatic MIP-101 and Clone A cells. Subsequent immunohistochemical analysis of 81 primary human CRC tissues demonstrated that the expression of Hsp70 and Hsp110 was highly correlated with the advanced clinical stages and positive lymph node involvement. The expression of Bcl-2, in contrast, was correlated to the early clinical stage and negative lymphovascular invasion. Conclusion: Taken together, our study demonstrated for the first time a differential, stage-dependent expression of Hsp70, Hsp110 and Bcl-2 in CRC. We suggest that the molecular mechanisms underlying the differential expression of Hsp and Bcl-2 family members deserves a more rigorous future study, the results of which might offer novel modes of rationale and strategy to predict and manipulate the malignant progression of colorectal cancers. [source] Predicting and monitoring cancer treatment response with diffusion-weighted MRIJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2010Harriet C. Thoeny MD Abstract An imaging biomarker that would provide for an early quantitative metric of clinical treatment response in cancer patients would provide for a paradigm shift in cancer care. Currently, nonimage based clinical outcome metrics include morphology, clinical, and laboratory parameters, however, these are obtained relatively late following treatment. Diffusion-weighted MRI (DW-MRI) holds promise for use as a cancer treatment response biomarker as it is sensitive to macromolecular and microstructural changes which can occur at the cellular level earlier than anatomical changes during therapy. Studies have shown that successful treatment of many tumor types can be detected using DW-MRI as an early increase in the apparent diffusion coefficient (ADC) values. Additionally, low pretreatment ADC values of various tumors are often predictive of better outcome. These capabilities, once validated, could provide for an important opportunity to individualize therapy thereby minimizing unnecessary systemic toxicity associated with ineffective therapies with the additional advantage of improving overall patient health care and associated costs. In this report, we provide a brief technical overview of DW-MRI acquisition protocols, quantitative image analysis approaches and review studies which have implemented DW-MRI for the purpose of early prediction of cancer treatment response. J. Magn. Reson. Imaging 2010. © 2010 Wiley-Liss, Inc. [source] PKC theta, a novel immunohistochemical marker for gastrointestinal stromal tumors (GIST), especially useful for identifying KIT-negative tumorsPATHOLOGY INTERNATIONAL, Issue 3 2005Atsushi Motegi Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor in the digestive tract and the majority of GIST has characteristic gain-of-function mutations of the c-kit gene, which encodes the KIT receptor for stem cell factor. The present study aimed to establish the usefulness of protein kinase C theta (PKC ,) as an immunohistochemical marker for GIST in comparison with KIT immunohistochemistry. PKC , immunohistochemistry was carried out not only on 48 cases of GIST and another 40 cases of gastrointestinal mesenchymal tumors, but also on 24 cases of various tumors known to be immunohistochemically positive for KIT. Immunohistochemically, 41 out of 48 cases (85%) of GIST were positive for PKC ,, and its expression was confirmed by Western blot analysis using six cases of surgically resected GIST. In the present study there were six GIST immunohistochemically negative for KIT, which histologically revealed a myxoid epithelioid appearance characteristic to that of GIST with platelet-derived growth factor receptor alpha mutation. All six GIST were immunohistochemically positive for PKC ,. No PKC , immunoreactivity was observed in other gastrointestinal mesenchymal tumors and various KIT-positive tumors except for three cases (14%) of gastrointestinal schwannomas. The present study revealed that PKC , is an immunohistochemically novel and useful marker for GIST, especially for GIST negative for KIT. [source] Apoptosis as an independent prognostic indicator in squamous cell carcinoma of the esophagusPATHOLOGY INTERNATIONAL, Issue 7 2001Hiroshi Shibata Apoptosis plays a crucial role in determining net cell proliferation and cell turnover in various tumors. The rate of apoptosis in tumor cells has been reported to be a useful prognostic indicator in colorectal carcinoma. We examined apoptosis in 72 specimens of esophageal squamous cell carcinoma, by the terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) digoxigenin,nick end labeling (TUNEL) method. We examined correlation of apoptosis with outcome, clinicopathological features, and expression of the apoptosis-related proteins p53 and Bcl-2. The percentage of apoptotic cells, or apoptotic index (AI), ranged from 0.8 to 9.4 (mean: 3.47; SD: 2.02). Overall, 5-year survival of patients with high AI (AI , 5.0; n= 18) tumors was significantly higher than that of patients with low AI tumors (AI < 5.0; n= 58; 76.9% versus 44.9%; P= 0.042). AI did not correlate significantly with the clinicopathological features of patient age and sex, depth of tumor and histological differentiation, lymph node metastasis, lymphatic invasion, or venous invasion. In p53-negative tumors, the AI was significantly higher than in p53-positive tumors. We concluded that AI may be a useful prognostic indicator in esophageal squamous cell carcinoma following curative surgery, and that apoptosis in this tumor is related to relative underexpression of p53 protein. [source] Hypermethylation in promoter region of E-cadherin gene is associated with tumor dedifferention and myometrial invasion in endometrial carcinomaCANCER, Issue 4 2003Ph.D., Tsuyoshi Saito M.D. Abstract BACKGROUND Loss of E-cadherin expression is associated with aberrant 5, CpG island methylation in various tumors. METHODS The authors analyzed the methylation status and immunohistochemical expression of E-cadherin in 142 endometrial tissues, consisting of 21 normal endometria, 17 endometrial hyperplasias, and 104 endometrial carcinomas. RESULTS All normal endometria and endometrial hyperplasias showed positive staining of E-cadherin, and methylation of the E-cadherin gene was not detected in any samples. In endometrial carcinoma, the positive ratio of methylation was higher and was associated with tumor dedifferention and myometrial invasion. In G1 endometrial adenocarcinomas, 66.7% showed positive staining and 33.3% showed heterogeneous staining. Methylation of the E-cadherin gene was detected in 15.6%. In G2 tumors, 19.0% showed positive staining, 69.0% showed heterogeneous staining and 11.9% showed negative staining. Methylation of the E-cadherin gene was found in 50.0%. In G3 tumors, 9.1% showed positive staining, 54.5% showed heterogeneous staining and 36.3% showed negative staining. Methylation of the E-cadherin gene was found in 81.8% of the tumors. Of the samples with no-myometrial invasion, 23.1% had methylation. In those with invasion in less than half of the myometrium, 28.6% did and in those with invasion of half or more of the myometrium, 55.6% had methylation. Of samples that did not have lymph node metastasis, 33.7% had methylation, whereas of samples that had lymph node metastasis, 60.0% had methylation. CONCLUSIONS This is the first report to analyze methylation of the E-cadherin gene promoter of endometrial carcinoma and the evidence suggests that methylation of the E-cadherin gene occurs in association with the acquisition of invasive capacity. Cancer 2003;97:1002,9. © 2003 American Cancer Society. DOI 10.1002/cncr.11157 [source] Induction of cell apoptosis in non-small cell lung cancer cells by cyclin A1 small interfering RNACANCER SCIENCE, Issue 10 2006Nam Hoon Cho Cyclin A1 and cyclin B1 are overexpressed in various tumors but are present at low levels in normal tissues. Cyclin A1 is restricted to germ cells undergoing meiosis. In order to explore the possibility of using cyclin A1 and cyclin B1 as anticancer targets, we knocked them down in two lung cancer cell lines, H157 and H596, using siRNA. As with cyclin A1 siRNA in lung cancer cell lines, cyclin B1, Cdc2 and CDK2 were all significantly downregulated. The S phase fraction increased significantly, and they eventually underwent apoptosis by way of downregulated intrinsic apoptotic pathways and modulators with upregulated extrinsic apoptotic pathways. Our study suggests that cyclin A1 might be a promising anticancer target specific to lung cancer. (Cancer Sci 2006; 97: 1082,1092) [source] The role of thymidine phosphorylase, an angiogenic enzyme, in tumor progressionCANCER SCIENCE, Issue 11 2004Shin-ichi Akiyama Thymidine phosphorylase (TP), an enzyme involved in pyrimidine metabolism, is identical with an angiogenic factor, platelet-derived endothelial cell growth factor (PD-ECGF). TP is overex-pressed in various tumors and plays an important role in angiogenesis, tumor growth, invasion and metastasis. The enzymatic activity of TP is required for the angiogenic effect of TP. A novel, specific TP inhibitor, TPI, inhibits angiogenesis induced by overexpression of TP in KB/TP cells (human KB epidermoid carcinoma cells transfected with TP cDNA), as well as the growth and metastasis of KB/TP cells in vivo. 2-Deoxy-D-ribose, the degradation product of thymidine generated by TP activity, has both angiogenic and chemotactic activity. Both 2-deoxy-D-ribose and TP inhibit a hypoxia-induced apoptotic pathway. These findings suggest that 2-deoxy-D-ribose is a downstream mediator of TP function. 2-Deoxy-L-ribose, a stereoisomer of 2-deoxy-D-ribose, inhibits the promotion of angiogenesis, tumor growth and metastasis by TP. Although the mechanism of the action of 2-deoxy-D-ribose is still unknown, 2-deoxy-L-ribose may inhibit the physiological activities of 2-deoxy-D-ribose, and consequently those of TP. Inhibition of TP activity and function appears to be a promising approach for the chemotherapy of various tumors. [source] Antitumor activity of sugar-modified cytosine nucleosidesCANCER SCIENCE, Issue 2 2004Akira Matsuda Nucleoside analogues which show antimetabolic activity in cells have been successfully used in the treatment of various tumors. Nucleosides such as 1-,-D-arabinofuranosylcytosine (araC), 6-mercaptopurine, fludarabine and cladribine play an important role in the treatment of leukemias, while gemcitabine, 5-fluorouracil and its prodrugs are used extensively in the treatment of many types of solid tumors. All of these compounds are metabolized similarly to endogenous nucleosides and nucleotides. Active metabolites interfere with the de novo synthesis of nucleosides and nucleotides or inhibit the DNA chain elongation after being incorporated into the DNA strand as terminators. Furthermore, nucleoside antimetabolites incorporated into the DNA strand induce strand-breaks and finally cause apoptosis. Nucleoside antimetabolites target one or more specific enzyme(s). The mode of inhibitory action on the target enzyme is not always similar even among nucleoside antimetabolites which have the same nucleoside base, such as araC and gemcitabine. Although both nucleosides are phosphorylated by deoxycytidine kinase and are also good substrates of cytidine deaminase, only gemcitabine shows antitumor activity against solid tumors. This suggests that differences in the pharmacological activity of these nucleoside antimetabolites may reflect different modes of action on target molecules. The design, in vitro cytotoxicity, in vivo antitumor activity, metabolism and mechanism of action of sugar-modified cytosine nucleosides, such as (2,S)-2,-deoxy-2,-C-methylcytidine (SMDC), 1-(2-deoxy-2-methylene-,-D-erythro-pentofuranosyl)cytosine (DMDC), 1-(2-C-cyano-2-deoxy-1-,-D-arabino-pentofuranosyl)cytosine (CNDAC) and 1-(3-C-ethynyl-,-D-ribo-pentofuranosyl)cytosine (ECyd), developed by our groups, are discussed here. [source] Regulation of TGF-, signaling and its roles in progression of tumorsCANCER SCIENCE, Issue 3 2003Kohei Miyazono Transforming growth factor-, (TGF-,) is a potent growth inhibitor of most types of cells; therefore, perturbations of TGF-, signaling are believed to result in progression of various tumors. On the other hand, TGF-, has been shown to act as an oncogenic cyto-kine through induction of extracellular matrices, angiogenesis, and immune suppression. A wide variety of effects of TGF-p are mediated by physical interaction of signal transducer Smad proteins with various transcription factors. Among these, Runx3 plays a pivotal role in prevention of gastric cancer. TGF-, signaling is regulated by various mechanisms in the cytoplasm and nucleus. Inhibitory Smads (l-Smads) repress TGF-, signaling mainly by interacting with activated TGF-, receptors. Smad ubiquitin regulatory factors (Smurfs) play important roles in facilitating the inhibitory signals induced by l-Smads. In addition, the transcrip-tional co-repressors c-Ski and SnoN interact with Smads, and repress transcription induced by TGF-,. Abnormalities of these regulators of TGF-, signaling may thus participate in the progression of various tumors. (Cancer Sci 2003; 94: 230,234) [source] | ||||||||||||||||||||||