MET overexpression assessed by new interpretation method predicts gene amplification and poor survival in advanced gastric carcinomas.

The establishment of better selection criteria for identifying sub-populations that may benefit from treatment is a key aspect of the development and success of targeted therapy. To investigate methods for assessing MET overexpression in gastric cancer, we conducted immunohistochemistry using a new anti-Total MET monoclonal antibody in a single-institution cohort of 495 patients. As antibody is directed against a membranous and/or cytoplasmic epitope, two interpretation methods were used: (1) membranous and cytoplasmic and (2) membranous alone. In selected 120 cases, copy number gain and mRNA expression levels were measured using quantitative real-time PCR. Further in situ hybridization confirmed the presence of MET gene amplification. Among the 495 gastric cancers, simultaneous membranous and cytoplasmic overexpression of MET was found in 108 cases (21.8%) and membranous alone overexpression was observed in 40 cases (8.1%). The highest correlation was observed in membranous and cytoplasmic staining of MET: MET expression scores correlated significantly with high MET mRNA levels (r=0.465, P<0.0001), increased copy number gain (r=0.393, P=0.000002) and amplification of MET gene. Moreover, patients with MET overexpression showed shorter overall survival (HR, 1.781; 95% CI, 1.324-2.395; P<0.001) and disease-free survival (HR, 1.765; 95% CI, 1.227-2.541; P=0.002) compared with patients without MET overexpression. However, membranous overexpression of MET did not highly correlate with mRNA level (r=0.274, P=0.002), copy number gain or survival (P>0.05). We developed highly correlating interpretation methods of MET immunohistochemistry in gastric carcinomas. MET overexpression is an independent prognostic factor and could be a potential target and predictor of benefit for targeted therapy with MET inhibitors.

Incidental microscopic bile duct tumor thrombi in hepatocellular carcinoma after curative hepatectomy: a matched study.

In patients with hepatocellular carcinoma (HCC), the presence of bile duct tumor thrombi (BDTT) in the major bile ducts indicates poor prognosis compared with that of HCC patients without BDTT. However, the prognostic significance of incidental microscopic BDTT in the peripheral bile ducts after curative liver resection is not known. We compared the outcomes of HCC patients with and without microscopic BDTT in the peripheral bile ducts who underwent hepatectomy.The electronic medical records of 31 patients with microscopic BDTT (BDTT group) were retrospectively reviewed. To compare the surgical outcomes, 62 patients (No BDTT group) were randomly chosen from the remaining HCC patients without BDTT based on age, sex, etiology of HCC, tumor size, tumor number, and modified Union for International Cancer Control T staging.The 1-year, 2-year, and 3-year disease-free survival rates and overall survival rates were 54.8%, 34.0%, 34.0% and 90.1%, 69.2%, 61.0% in the BDTT group and 66.8%, 59.2%, 42.3% and 86.4%, 84.4%, 84.4% in the No BDTT group (P = 0.089 and P = 0.014, respectively). The overall survival curve in the No BDTT group was higher than that in the BDTT group. Multivariate analysis revealed that predisposing factors for tumor recurrence after curative liver resection included increased levels of the protein induced by vitamin K antagonist-II (PIVKA-II), tumor grades 3 and 4, and the presence of BDTT.This study demonstrates that HCC prognosis is worse in patients with incidental microscopic BDTT in the peripheral bile ducts than it is in those without BDTT. The presence of BDTT should therefore be considered when evaluating a patient's HCC prognosis after curative hepatectomy.

Progressive methylation during the serrated neoplasia pathway of the colorectum.

Serrated adenoma is a recently described entity characterized by having combined architectural features of hyperplastic polyps and classical adenoma. To understand the role of gene regulation in the progression of the serrated neoplasia pathway, we examined the methylation profiles of the promoter regions of 19 genes, DNA ploidy, and mutator phenotype status. In all, 40 sporadic, classical serrated adenomas were pathologically reviewed and divided into four pathologic groups according to their histologic grades. Methylation-specific PCR was performed using primers for p16, hMLH1, RASSF1A, APC, HIC-1, DAPK, MGMT, SLC5A8, RB1, H-Cadherin, E-Cadherin, TIMP3, PTEN, THBS1, LKB1, p14, p15, FHIT, and VHL. Dual flow-cytometric analyses using cytokeratin and DAPI and MSI studies using BAT26 were also performed. Methylation was observed in 2.5-82.5% (mean 33.9%) of the CpG islands in the promoter regions of 16 genes. The tumors with higher histologic grades, including carcinomas, showed more extensive methylation compared to those with lower grades, and serrated adenomas in the right colon showed more frequent methylation than those in the left (P<0.05). Tumor-specific promoter methylation of SLC5A8 was observed in 33 (82.5%) of the serrated adenomas. Aneuploidization with near-diploid DNA indices was detected in four out of 28 cases examined (14.3%); two were low-grade serrated adenomas and two were carcinomas in the left colon. The high mutator phenotype was not observed in any of the cases examined. Our results indicate that: (1) aberrant, widespread methylation of CpG islands increases with the histological progression of serrated adenomas; (2) methylation of SLC5A8 is an early event; and (3) additional methylation of the p16, p14, MGMT, TIMP3, and FHIT genes are important tumorigenic steps in the serrated neoplasia pathway.