p16INK4 gene mutations are relatively frequent in ampullary carcinomas

Ampulla of Vater carcinoma: advancement in the relationships between histological subtypes, molecular features, and clinical outcomes

The incidence of ampulla of Vater carcinoma, a type of periampullary cancer, has been increasing at an annual percentage rate of 0.9%. However, patients with ampulla of Vater carcinoma have quite different prognoses due to the heterogeneities of the tissue origin of this carcinoma. In addition to TNM staging, histological subtypes and molecular features of ampulla of Vater carcinoma are the key factors for predicting the clinical outcomes of patients. Fortunately, with the development of testing technology, information on the histological subtypes and molecular features of ampulla of Vater carcinoma is increasingly being analyzed in-depth. Patients with the pancreaticobiliary subtype have shorter survival times. In immunohistochemical examination, high cutoff values of positive MUC1 staining can be used to accurately predict the outcome of patients. Mutant KRAS, TP53, negative SMAD4 expression, and microsatellite stability are related to poor prognosis, while the clinical value of BRCA1/BRCA2 mutations is limited for prognosis. Testing the histological subtypes and molecular characteristics of ampulla of Vater carcinoma not only is the key to prognosis analysis but also provides extra information for targeted treatment to improve the clinical outcomes of patients.

CDKN2A Germline Rare Coding Variants and Risk of Pancreatic Cancer in Minority Populations

Background: Pathogenic germline mutations in the CDKN2A tumor suppressor gene are rare and associated with highly penetrant familial melanoma and pancreatic cancer in non-Hispanic whites (NHW). To date, the prevalence and impact of CDKN2A rare coding variants (RCV) in racial minority groups remain poorly characterized. We examined the role of CDKN2A RCVs on the risk of pancreatic cancer among minority subjects.Methods: We sequenced CDKN2A in 220 African American (AA) pancreatic cancer cases, 900 noncancer AA controls, and 183 Nigerian controls. RCV frequencies were determined for each group and compared with that of 1,537 NHW patients with pancreatic cancer. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for both a case-case comparison of RCV frequencies in AAs versus NHWs, and case-control comparison between AA cases versus noncancer AA controls plus Nigerian controls. Smaller sets of Hispanic and Native American cases and controls also were sequenced.Results: One novel missense RCV and one novel frameshift RCV were found among AA patients: 400G>A and 258_278del. RCV carrier status was associated with increased risk of pancreatic cancer among AA cases (11/220; OR, 3.3; 95% CI, 1.5-7.1; P = 0.004) compared with AA and Nigerian controls (17/1,083). Further, AA cases had higher frequency of RCVs: 5.0% (OR, 13.4; 95% CI, 4.9-36.7; P < 0.001) compared with NHW cases (0.4%).Conclusions: CDKN2A RCVs are more common in AA than in NHW patients with pancreatic cancer and associated with moderately increased pancreatic cancer risk among AAs.Impact: RCVs in CDKN2A are frequent in AAs and are associated with risk for pancreatic cancer. Cancer Epidemiol Biomarkers Prev; 27(11); 1364-70. ©2018 AACR.

Aberrant promoter hypermethylation in biliary tract carcinoma

Biliary tract carcinoma is a relatively rare tumor with a poor survival rate. The molecular biological mechanisms underlying the development of biliary tract carcinomas are not well understood. Promoter methylation is an important epigenetic mechanism for suppressing tumor-suppressor gene activity. There is limited information regarding the abnormal methylation of cancer-related genes in biliary tract carcinoma; however, a few insights have been obtained into the role of epigenetic silencing in the progression of biliary tract carcinoma. In this review, we summarize recent data on gene silencing by promoter hypermethylation, and we discuss the implications for biliary tract carcinomas.

Alterations of p16 and prognosis in biliary tract cancers from a population-based study in China

PURPOSE

Biliary tract cancer is an uncommon malignancy with a poor survival rate. We evaluated p16 gene alteration as a prognostic marker for this disease.

EXPERIMENTAL DESIGN

We studied p16 gene alterations by sequencing, methylation, and loss of heterozygosity of chromosome 9p in 118 biliary tract carcinomas, including 68 gallbladder cancers, 33 extrahepatic bile duct cancers, and 17 ampullary cancers. Survival was evaluated in 57 patients with gallbladder carcinomas, 27 with bile duct carcinomas, and 16 with ampullary carcinomas with and without somatic p16 alterations detected by two different methods.

RESULTS

p16 gene alterations including silent mutations were present in 61.8% gallbladder cancers, 54.5% bile duct cancers, and 70.6% ampullary cancers. p16 gene nonsilent mutations, p16 methylation, and loss of chromosome 9p21-22 that targets p14, p15, and p16 genes were present in 13 of 53 (24.5%), 8 of 54 (14.8%), and 32 of 44 (72.7%) gallbladder tumors; 5 of 25 (20.0%), 5 of 31 (16.1%), and 12 of 21 (57.1%) bile duct tumors; and 3 of 13 (23.1%), 6 of 15 (40.0%), and 8 of 16 (50.0%) ampullary tumors, respectively. The mean survival of patients with gallbladder cancers without p16 alterations was 21.5 +/- 14.8 months compared with 12.1 +/- 11.4 months for patients with p16 alterations (P = 0.02).

CONCLUSIONS

Alteration of p16 gene alone or in combination with alterations of other tumor suppressor genes on chromosome 9p is a prognostic indicator in gallbladder carcinoma, with more favorable survival rates associated with carcinomas lacking p16 gene alterations.

Increased cyclin D1 expression in cancer of the ampulla of Vater: relevance to nuclear beta catenin accumulation and k-ras gene mutation

AIMS

Several studies have reported that dysregulation of beta catenin or k-ras mutation promotes cyclin D1 expression. This study investigated the relation between cyclin D1 expression and clinicopathological parameters in carcinoma of the ampulla of Vater (CAV), and also assessed the relation between increased cyclin D1 expression and beta catenin/k-ras status in this series.

METHODS

Thirty CAVs were evaluated for cyclin D1 expression by immunohistochemistry in relation to patient clinicopathological features. Aberrant beta catenin expression and k-ras mutation were also investigated by immunostaining and direct sequencing, and related to cyclin D1 expression.

RESULTS

Increased cyclin D1 expression was seen in 17 of 30 CAVs and was significantly correlated with tumour cell proliferation and disease free survival time (p = 0.018, p = 0.018, respectively). Nuclear accumulation of beta catenin was found in nine of 30 cases, including four cases with missense mutations in exon 3 of CTNNB-1, and was significantly correlated with increased cyclin D1 expression (p = 0.003). k-ras gene mutation was detected in 12 of 30 cases, and was also significantly correlated with increased cyclin D1 expression (p = 0.026). Overall, 14 of 17 CAVs with increased cyclin D1 expression showed nuclear accumulation of beta catenin and/or k-ras mutation.

CONCLUSIONS

Increased cyclin D1 expression appears to be associated with tumour proliferation and poorer clinical outcome in CAV. It is also associated with both aberrant beta catenin expression and k-ras mutation. These results are consistent with the in vitro data that cyclin D1 can be transactivated by activated beta catenin-T cell factor/LEF and k-ras pathways.

Genetic instability and mutation of the TGF-beta-receptor-II gene in ampullary carcinomas

Ampullary carcinomas are relatively rare cancers of which very little is known in terms of carcinogenetic mechanisms at the molecular level. Genetic instability caused by mutations of mismatch-repair genes has been demonstrated to be responsible for hereditary non-polyposis colorectal cancers and a sub-set of sporadic colorectal cancers. In some of those tumors showing genetic instability, the transforming-growth-factor-beta(TGF-beta)-receptor-II gene has been found to be mutated in repetitive sequences and considered to be a target of replication error. We studied the role of genetic instability and associated TGF-beta-receptor-II-gene mutations in a series of 18 sporadic cases by analyzing 5 microsatellite loci (D2S123, D3S1029, D5S409, TP53 and BAT26) and by sequencing a poly-A repeat (nucleotides 709-718) in the TGF-beta-receptor-II gene. Microsatellite instability was observed in 4 (22.2%) and gene mutations in 14 (77.8%) cases. These data indicate that the TGF-beta-receptor-II gene might be a preferential target of genetic instability whose alteration might be specifically advantageous and constitute a common step in the development of ampullary carcinomas.