UMLS:C0596263 - FACTA Search

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Query: UMLS:C0596263 (carcinogenesis)
64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A frequent genetic alteration found in premalignant stages of pancreatic adenocarcinoma is K-ras oncogene point mutation. The mechanistic basis for the inability of K-ras mutation to transform pancreatic ductal cells is unclear, although cooperating events with p16 inactivation, p53 mutation, and SMAD 4 mutation are recognized to be necessary. We have generated a novel mouse model in which the cytokeratin 19 promoter, specifically active in pancreatic ductal cells but not other cell types of the pancreas, is fused to mutant K-ras. This is of direct relevance to human pancreatic cancer because premalignant lesions are found specifically in ductal cells. There is dramatic periductal lymphocytic infiltration in the pancreata of transgenic mice, predominantly CD4+ T lymphocytes, which may act as an adaptive immune response to activated ras-mediated signaling. In addition, gene array analysis reveals an induction of N-cadherin in transgenic mice pancreatic ductal cells, the significance of which relates to promotion of cell adhesion and deterrence of cell migration. Apart from these important biological considerations, there is parallel activity of the cytokeratin 19 promoter in the stem cell region of the gastric epithelium, namely in mucous neck cells. Activated K-ras in this context causes mucous neck cell hyperplasia, a precursor to gastric adenocarcinoma. There is concomitant parietal cell decrease, which is a key step toward gastric adenocarcinoma. Taken together, we have defined how mutant K-ras signaling modulates important molecular events in the initiating events of pancreatic and gastric carcinogenesis.
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PMID:The mutant K-ras oncogene causes pancreatic periductal lymphocytic infiltration and gastric mucous neck cell hyperplasia in transgenic mice. 1272 9

The molecular basis of testicular germ cell tumourigenesis are not well elucidated. Growth factors regulate cell growth, differentiation and apoptosis. Major families of growth factors are present in the male gonad from early fetal development to adult life. They are involved in germ cell proliferation and differentiation. Growth signalling pathways suffer deregulation in many human malignancies. Given the importance of growth signals in normal testicular development and their acquired deregulation in most human cancers, growth factors and signalling molecules that have been implicated in the genesis of testicular germ cell tumours, are reviewed. We detected a somatic mutation of SMAD4 gene, responsible for loss of protein function in seminomas. This mutational inactivation may affect the activity of several members of TGFbeta superfamily (TGFbeta, activin, inhibin, BMP). VEGF expression has been shown to predict metastasis in seminomas. A significant association of HST-1 expression, a member of fibroblast growth factors, with the nonseminomatous phenotype and with tumour stage has been described. In contrast, C-KIT is expressed by seminomas only, from the preinvasive stage. Despite intense expression in almost all seminomas, activating mutation of C-KIT gene is seldom reported. Recently, the first animal model of classical testicular seminoma has been identified in transgenic mouse overexpressing GDNF. RET (GDNF receptor) expression is demonstrated in human seminomas, and not in nonseminomatous tumours. However, the exact molecular alterations of GDNF/RET/GFRalpha1 complex in germ cell tumours are not known. Finally, beside growth factors, other signalling molecules such as peptide hormones may be involved in testicular carcinogenesis. We have demonstrated a specific pattern of somatostatin receptors expression in each type of testicular germ cell tumours, with a loss of sst3 and sst4 in seminomas and loss of sst4 and expression of sst1 in nonseminomas only. These data suggest an antiproliferative action of somatostatin in testicular cancers. In summary, many growth factors and signalling molecules seem to represent specific markers for different histological types of germ cell tumours (seminomas versus nonseminomas) and may play a role in the differentiation of germ cell tumours. Despite a complex signalling pathway involved in the physiological functions of male gonad, little is known about the implication of this signalling network in testicular malignancies. From a practical stand-point, further studies on the role of growth factors in human germ cell tumours may offer a new therapeutical perspective with the development of specific pharmacological signalling modulators that could be used as therapeutic agents.
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PMID:Growth regulatory factors and signalling proteins in testicular germ cell tumours. 1275 64

Characterization of the protein profiles expressed by hepatocellular carcinomas (HCCs) may identify the genes involved in hepatocellular carcinogenesis and offers the possibility of elucidating clinical biomarkers. In an effort to discover such proteins and pathways that are deregulated in hepatocellular carcinogenesis, cellular proteomes of matched normal liver cells and carcinoma were analysed by tissue microdissection and protein microarrays. Using protein microarrays made up of 83 different antibodies, it was possible to monitor alterations of the protein levels in HCC and non-neoplastic liver tissue. Further analysis of altered proteins was performed using western blot analysis and tissue microarrays (TMAs) containing 210 HCC specimens and corresponding liver tissue. The protein microarray approach revealed differential expression between HCC and normal liver of 32 of the 83 proteins examined: 21 of these were up-regulated and 11 down-regulated. IGF (insulin growth factor) II, ADAM (a disintegrin and metalloproteases) 9, STAT (signal transducers and activators of transcription) 3, SOCS (suppressors of cytokine signalling) 3, and cyclin D1 were significantly up-regulated and collagen I, SMAD 4, FHIT (fragile histidine triad), and SOCS1 were down-regulated. The differential expression of these proteins was confirmed using western blot analysis and TMAs. Correlation of differentially regulated proteins with clinico-pathological data showed that cyclin D1 and SOCS1 were associated with tumour prognosis in univariate analysis, but not multivariate analysis. These data indicate that the development of an array-based approach for the determination of protein profiles in HCC may facilitate the identification of new proteins associated with carcinogenesis or prognosis.
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PMID:Identification of novel proteins associated with hepatocellular carcinomas using protein microarrays. 1451 41

TGF-beta is a multifunctional cytokine which regulates cell growth, extracellular matrix deposition, cell differentiation, and immunosuppression etc. The signal is mainly mediated through Smad pathway to inhibit epithelial cell growth. In 50% of pancreatic cancer, Smad4/DPC4 gene is deleted or mutated, which might cause pancreatic carcinogenesis and be associated with highly invasive and metastatic character of the disease. On the other hand, TGF-beta signal itself has recently been shown to act in favor of cancer cells, especially in the late phase of tumor progression. In Smad4-inactivated pancreatic cancer cells, TGF-beta signal regulates a number of genes involved in tumor suppression and progression. The regulated genes and signaling pathways of TGF-beta signal should be investigated to obtain an effective therapeutic target molecule for pancreatic cancer.
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PMID:[TGF-beta signaling pathway in pancreatic cancer cells]. 1528 39

DUSP6/MKP-3 is identified as a candidate tumor suppressor gene for pancreatic cancer. The aim of this study was to elucidate the roles of DUSP6 in the pancreatic carcinogenesis through the pancreatic intraepithelial neoplasia and/or intraductal papillary-mucinous neoplasms, both of which are considered to be precursor lesions of invasive carcinoma of the pancreas, by comparing with involvements of other major tumor suppressive pathways. Expressions of DUSP6, CDKN2A, TP53, and SMAD4 were investigated by immunohistochemistry in a total of 206 lesions of dysplastic ductal precursors and carcinomas retrieved from 52 pancreata with invasive ductal carcinomas and 51 of those with intraductal papillary-mucinous neoplasms. The intensity of staining was evaluated in lesions at different atypical grades and statistically compared among them. Mutations of KRAS2 were analyzed by methods of the allele-specific oligonucleotide hybridization and nucleotide sequencing. In pancreata with invasive ductal carcinomas, expressions of DUSP6 were abrogated exclusively in the invasive carcinoma cells in contrast to its fairly preserved expressions in pancreatic intraepithelial neoplasia. In pancreata with intraductal papillary-mucinous neoplasms, abrogated expressions of DUSP6 were observed in a relatively small fraction of intraductal adenoma/borderlines and intraductal carcinomas. Most of the intraductal adenoma/borderline lesions with abrogation of DUSP6 harbored mutations of KRAS2. None of the molecules was associated with each other in any grade of lesions. Morphological variations of papillae of the intraductal papillary-mucinous neoplasms were evaluated and analyzed for their associations with abrogations of the molecules, which resulted in finding of no significant associations. Our results suggest that the abrogation of DUSP6 is associated exclusively with progression from pancreatic intraepithelial neoplasia to the invasive ductal carcinoma while it is potentially associated with initiation of intraductal papillary-mucinous neoplasms with mutated KRAS2, which is independent of other major tumor suppressive pathways in both types of neoplasms.
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PMID:Distinct progression pathways involving the dysfunction of DUSP6/MKP-3 in pancreatic intraepithelial neoplasia and intraductal papillary-mucinous neoplasms of the pancreas. 1583 94

The SMADs are a group of interrelated proteins that mediate transforming growth factor beta (TGF-beta) signaling. Upon TGF-beta binding the TGF-beta type I receptor phosphorylates Smad2 and Smad3, which then complex with Smad4 and translocate to the nucleus, with subsequent activation of target genes. Disruption of TGF-beta signaling is thought to contribute to the development of head and neck squamous cell carcinomas (HNSCC). Alterations in the function of the DPC4/Smad4 tumor suppressor gene have been found to inactivate TGF-beta signaling in several tumor types. For example, DPC4/Smad4 is lost or mutated in colorectal, pancreatic, and esophageal cancers. In addition, DPC4/Smad4 transcriptional activity and TGF-beta ability to inhibit DNA synthesis is blocked by the E7 protein of the human papillomavirus type 16 (HPV16) in cervical carcinoma cell lines. HPV16 infection is a risk factor for the development of a subset of HNSCC. This study was undertaken to investigate a potential correlation between expression of components of the TGF-beta signaling pathway and HPV16 status in HNSCC tumors. We examined the expression of TGF-beta signaling proteins Smad2, Smad2-P, and Smad4 by immunohistochemistry in 27 HPV16-negative and 16 HPV16-positive HNSCCs. We compared the expression patterns and assessed their relationship to HPV16 status. No significant differences were detected between HPV16-positive and HPV16-negative tumors in the expression of Smad2 and Smad2-P. Smad4 expression, however, was decreased in 56% of the HPV16-positive tumors and in 39% of HPV16-negative tumors. This difference was statistically significant (P = 0.01) suggesting that loss of Smad4 expression may be involved in HPV16-induced carcinogenesis of HNSCC.
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PMID:Differences in Smad4 expression in human papillomavirus type 16-positive and human papillomavirus type 16-negative head and neck squamous cell carcinoma. 1586 6

Pancreatic cancer is one of the most lethal tumours of the gastrointestinal tract. The ability to predict which patients would benefit most from surgical intervention and/or chemotherapy would be a great clinical asset. Considerable research has focused on identifying molecular events in pancreatic carcinogenesis, and their correlation with clinicopathological variables of pancreatic tumours and survival. This systematic review examined evidence from published manuscripts looking at molecular markers in pancreatic cancer and their correlation with tumour stage and grade, response to chemotherapy and long-term survival. A literature search was undertaken using PubMed and MEDLINE search engines, using the keywords p53, p21, p16, p27, SMAD4, K-ras, cyclin D1, Bax, Bcl-2, EGFR, EGF, c-erbB2, HB-EGF, TGFbeta, FGF, MMP, uPA, cathepsin, heparanase, E-cadherin, laminins, integrins, TMSF, CD44, cytokines, angiogenesis, VEGF, IL-8, beta-catenin, DNA microarray, and gene profiling. A bewildering number of biomarkers are currently under evaluation. For the most part, the evidence regarding their application as prognostic indicators is conflicting. The advent of gene microarray and mass spectrometric protein profiling offers the potential to examine many different biomarkers simultaneously. This 'protein/gene signature' could revolutionise work in this field and allow researchers to develop accurate and reproducible predictions of survival based on protein or gene profiles.
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PMID:Molecular prognostic markers in pancreatic cancer: a systematic review. 1614 90

Most pancreatic neoplasia are of ductal lineage, characterized by tubule (gland), cyst, papilla, or mucin formation and expression of mucin-related glycoproteins and oncoproteins (eg, MUC1, CA19-9, CEA, DUPAN), as well as some subsets of cytokeratin (eg, CK19). Mutations of k-ras oncogene and DPC4 are also common in ductal neoplasia and generally not seen in nonductal tumors. A variety of pancreatic neoplasia fall under the heading of ductal neoplasia. Invasive ductal adenocarcinoma (DA) is the most important and constitutes the vast majority (>85%) of pancreatic tumors. DA is characterized by insidious infiltration and rapid dissemination, despite its relatively well-differentiated histologic appearance. In some variants of DA such as undifferentiated or sarcomatoid, evidence of ductal differentiation may be lacking or only focal. The presumed precursors of DA are microscopic intraductal proliferative changes that are now termed pancreatic intraepithelial neoplasia (PanIN). PanINs comprise a neoplastic transformation ranging from early mucinous change (PanIN-1A) to frank CIS (PanIN-3). A similar (in situ) neoplastic spectrum also characterizes intraductal papillary mucinous neoplasms and mucinous cystic neoplasms, which are cystic ductal-mucinous tumors with varying degrees of papilla formation, and may be associated with invasive carcinoma. As such, these can be regarded as mass-forming preinvasive neoplasia. Some intraductal papillary mucinous neoplasms are associated with invasive carcinoma of the colloid type. Colloid carcinoma of the pancreas appears to be a clinicopathologically distinct tumor with indolent behavior. Whereas most ductal pancreatic neoplasia are characterized by some degree of mucin formation, serous tumors, of which serous (microcystic) adenoma is the sole example, lack mucin formation, presumably because they recapitulate centroacinar ducts. They are typically benign tumors. It is recognized now that pancreatic carcinoma, like other malignant processes, is a genetic disease produced by progressive mutations in cancer-related genes. These alterations can be categorized as "early" such as k-ras mutation, HER-2/neu, PSCA, MUC5, and fascin overexpression; "intermediate" such as p16 inactivation, MUC1, and cyclin D1 overexpression; and finally as "late" such as p53 and DPC4 inactivation, BRCA2 mutation, and overexpression of ki-67, 14-3-3sigma, and mesothelin. Ductal neoplasia is the most important category among pancreatic tumors. It is important to appreciate the different types of ductal tumors because they vary greatly in their clinicopathologic characteristics and prognosis. Understanding the molecular mechanisms of ductal carcinogenesis will help develop more efficient prevention and therapy of these tumors.
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PMID:Ductal neoplasia of the pancreas: nosologic, clinicopathologic, and biologic aspects. 1618 79

Pancreatic ductal adenocarcinoma is one of the most fatal malignancies. Intensive investigation of molecular pathogenesis might lead to identifying useful molecules for diagnosis and treatment of the disease. Pancreatic ductal adenocarcinoma harbors complicated aberrations of alleles including losses of 1p, 6q, 9p, 12q, 17p, 18q, and 21q, and gains of 8q and 20q. Pancreatic cancer is usually initiated by mutation of KRAS and aberrant expression of SHH. Overexpression of AURKA mapping on 20q13.2 may significantly enhance overt tumorigenesity. Aberrations of tumor suppressor genes synergistically accelerate progression of the carcinogenic pathway through pancreatic intraepithelial neoplasia (PanIN) to invasive ductal adenocarcinoma. Abrogation of CDKN2A occurs in low-grade/early PanIN, whereas aberrations of TP53 and SMAD4 occur in high-grade/late PanIN. SMAD4 may play suppressive roles in tumorigenesis by inhibition of angiogenesis. Loss of 18q precedes SMAD4 inactivation, and restoration of chromosome 18 in pancreatic cancer cells results in tumor suppressive phenotypes regardless of SMAD4 status, indicating the possible existence of a tumor suppressor gene(s) other than SMAD4 on 18q. DUSP6 at 12q21-q22 is frequently abrogated by loss of expression in invasive ductal adenocarcinomas despite fairly preserved expression in PanIN, which suggests that DUSP6 works as a tumor suppressor in pancreatic carcinogenesis. Restoration of chromosome 12 also suppresses growths of pancreatic cancer cells despite the recovery of expression of DUSP6; the existence of yet another tumor suppressor gene on 12q is strongly suggested. Understanding the molecular mechanisms of pancreatic carcinogenesis will likely provide novel clues for preventing, detecting, and ultimately curing this life-threatening disease.
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PMID:Molecular mechanisms of pancreatic carcinogenesis. 1636 14

The role of the TGF-beta-Smad signaling pathway in the carcinogenesis of head and neck cancer has not been fully evaluated genetically. In this study, we screened for mutation in the five main members of the TGF-beta -Smad signaling pathway, TGF-beta type I receptor (TGFBRI), TGF-beta type II receptor (TGFBRII), SMAD2, SMAD3 and SMAD4, in eight human head and neck squamous cell carcinoma (HNSCC) cell lines. Two mutations with presumed loss of heterozygosity (LOH) were identified. A novel missense mutation of SMAD2, located in exon 8 at codon 276 TCG (ser) -->TTG (leu), was identified in cell line SCC-15. This is the first report of a biallelic mutation of the SMAD2 gene in HNSCC. A nonsense mutation of the SMAD4 gene in exon 5 codon 245 CAG (glut) -->TAG (stop) was found in cell line CAL27. Western blotting verified that this nonsense mutation gives rise to the complete loss of the Smad4 protein in the cells. While the down-regulation and loss of expressions of the TGF-beta-Smad signaling pathway have been described frequently in HNSCC, here we offer further genetic evidence that the pathway is directly targeted for mutation during the HNSCC tumorigenesis.
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PMID:Disruption of transforming growth factor beta-Smad signaling pathway in head and neck squamous cell carcinoma as evidenced by mutations of SMAD2 and SMAD4. 1647 46

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