MTS-1 is a candidate tumor suppressor gene on chromosome 9p21-22, a region frequently observed to have loss of heterozygosity in esophagus squamous cell carcinomas and pancreatic ductal adenocarcinomas.
MTS1 gene mutations were detected in 2 adenocarcinomas only; gene methylation was observed in 17 of 72 cases (24%) without any correlations with the variables investigated.
Aberrant methylations of p16INK4a and p14ARF gene were present in 21 (32.3%) and 33 (50.8%) out of 65 cases, respectively. p16INK4a aberrant methylation was correlated with p16 negativity (P=0.021) and p53 overexpression (P=0.007). p16INK4a aberrant methylation was more frequently present in poorly differentiated adenocarcinomas (P=0.002).
Abnormalities involving the p16 (also known as cyclin-dependent kinase N2 [CDKN2], p16 [INK4a], or MTS1) and p53 (also known as TP53) tumor suppressor genes are highly prevalent in esophageal adenocarcinomas.
Additionally, we analysed the aberrant methylation frequency of cell cycle inhibitor p16(INK4a) and K-ras gene mutations in the pancreatic samples. p16 inactivation was detected in 43% of adenocarcinomas, in 17% of neuroendocrine tumors, in 18% of pancreatitis and in 63% of pancreas cancer cell lines.
All the GNAS-mutated LEGHs were negative for HPV DNA and p16 expression, whereas all the GNAS-mutated adenocarcinomas were positive for HPV DNA and/or p16 expression, implicating GNAS mutations in the development of LEGH and a minor subset of HPV-related cervical adenocarcinomas.
Both the adenocarcinoma and squamous cell carcinoma components revealed an inverse correlation between the expression pattern of p16 and RB proteins (p < 0.05).
CpG methylation as well as histone H3 methylation of lysines 9 and 27 contribute independently to ARF gene silencing in adenocarcinoma cell lines and can be reversed by 5-aza-2'-deoxycytidine.
Diffuse immunostaining for p16INK4a, a potential marker of hrHPV E7 function, was significantly more frequent in hrHPV-positive cervical AdCAs (19/20; 95%) than in those without hrHPV (1/5; 20%; p<0.001).
Distinction of endocervical and endometrial adenocarcinomas: immunohistochemical p16 expression correlated with human papillomavirus (HPV) DNA detection.
Distinction of serous carcinomas from endocervical adenocarcinomas (HPV-related type), both of which share diffuse p16 expression and frequently lack hormone receptor expression, relies on morphology and diffuse/strong p53 expression in the former and detection of HPV in the latter.
Expression of the tumor suppressor gene p16 in pulmonary adenocarcinoma decreased, mainly as a result of aberrant methylation of the CpG islands of the promoter region.
Fourteen of 15 (93.3%) invasive pancreatic ductal adenocarcinomas showed methylation of the ppENK gene and 4 of 15 (26.7%) showed methylation of the p16 gene.
Here we demonstrate that exposure to plutonium may elevate the risk for adenocarcinoma through specifically targeting the p16 gene for inactivation by promoter methylation.
Homozygous deletion of p16 appears to be common in esophageal squamous cell carcinomas but in adenocarcinomas, both gene deletion and transcriptional silencing of p16 were infrequent.
However, p16 mRNA levels (relative to matched normal epithelia) were variable in Barrett's epithelia and adenocarcinomas, having no clear correlation with methylation status or other molecular and clinico-pathological parameters.