Deletion of cadherin-17 enhances intestinal permeability and susceptibility to intestinal tumour formation.

Cadherin-17 is an adhesion molecule expressed specifically in intestinal epithelial cells. It is frequently underexpressed in human colorectal cancer. The physiological function of cadherin-17 and its role in tumourigenesis have not yet been determined. We used the transcription activator-like effector nuclease technique to generate a Cdh17 knockout (KO) mouse model. Intestinal tissues were analysed with histological, immunohistochemical and ultrastructural methods. Colitis was induced by oral administration of dextran sulphate sodium (DSS), and, to study effects on intestinal tumourigenesis, mice were given azoxymethane (AOM) and DSS to induce colitis-associated cancer. Cdh17 KO mice were viable and fertile. The histology of their small and large intestines was similar to that of wild-type mice. The junctional architecture of the intestinal epithelium was preserved. The loss of cadherin-17 resulted in increased permeability and susceptibility to DSS-induced colitis. The AOM/DSS model demonstrated that Cdh17 KO enhanced tumour formation and progression in the intestine. Increased nuclear translocation of Yap1, but not of ß-catenin, was identified in the tumours of Cdh17 KO mice. In conclusion, cadherin-17 plays a crucial role in intestinal homeostasis by limiting the permeability of the intestinal epithelium. Cadherin-17 is also a tumour suppressor for intestinal epithelia. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Biological significance of TERT promoter mutation in papillary urothelial neoplasm of low malignant potential.

AIMS: Mutations in FGFR3 and the promoter region of the telomerase reverse transcriptase (TERT) gene have been found frequently in urothelial carcinoma of the urinary bladder. However, related data for papillary urothelial neoplasm of low malignant potential (PUNLMP) are limited. In this study, we investigated the mutation status of the TERT promoter, FGFR3 and HRAS in low-grade papillary urothelial neoplasms and evaluated their prognostic significance. METHODS AND RESULTS: The cases included in this study comprised 21 inverted papillomas, 30 PUNLMPs and 34 low-grade non-invasive papillary urothelial carcinomas (NIPUCs). TERT promoter mutations were observed in 10 (33%) PUNLMPs and 17 (50%) low-grade NIPUCs, but not in any inverted papilloma. FGFR3 mutations were observed more frequently in PUNLMP and low-grade NIPUC than in inverted papillomas (P = 0.009), whereas the opposite trend was noted for HRAS mutations (P < 0.001). Regarding the clinical outcome, TERT promoter mutation was associated with a higher recurrence rate in PUNLMP (P = 0.024) but not in low-grade NIPUC (P = 0.530). Notably, PUNLMP cases with TERT promoter mutations had a similar recurrence rate to that in low-grade NIPUC cases (P = 0.487). CONCLUSIONS: Our results suggest that the status of the TERT promoter mutation may serve as a biomarker of prognostic stratification in patients with PUNLMP.

Carbonic anhydrase VI: a novel marker for salivary serous acinar differentiation and its application to discriminate acinic cell carcinoma from mammary analogue secretory carcinoma of the salivary gland.

AIMS: Carbonic anhydrase VI (CA6) is present in serous acinar cells of human salivary glands. The aim of this study was to investigate the diagnostic utility of CA6 in differentiating acinic cell carcinoma (AciCC) from its morphological mimic mammary analogue secretory carcinoma (MASC) of the salivary gland. METHODS AND RESULTS: CA6 immunostaining was performed in 28 cases of AciCC and 14 cases of MASC. All cases of AciCC showed positive CA6 staining. The staining pattern correlated with the number of serous acinar cells in tumours. All MASCs stained negatively for CA6. The results were compared with those obtained with currently used markers, including DOG1, mammaglobin, S100, and vimentin. CA6 showed sensitivity and specificity as high as those of DOG1 in diagnosing AciCC. CA6 expression was focally observed in basal cell adenoma and in one case of cystadenocarcinoma (1/3), but not in other salivary gland tumours, including mucoepidermoid carcinoma, adenoid cystic carcinoma, salivary duct carcinoma, lymphoepithelial carcinoma, epithelial-myoepithelial carcinoma, and pleomorphic adenoma. CONCLUSIONS: CA6 is a specific marker for serous acinar cells of salivary glands and AciCC. CA6 has sensitivity and specificity equal to those of DOG1 in the differential diagnosis between AciCC and MASC. A combination of CA6 and DOG1 could be an ideal immunohistochemical panel for AciCC.

Tumor-matrix interaction induces phenotypic switching in liver cancer cells.

BACKGROUND: Intrahepatic cholangiocarcinoma (ICC) is characterized by fibrous stroma and clinical behavior more aggressive than that of hepatocellular carcinoma (HCC). Scirrhous HCC is a subtype of HCC with fibrous stroma, frequently has partial cholangiocytic differentiation, and is more likely to have an aggressive behavior. This study explored the interaction of liver cancer cells with the extracellular matrix. METHODS AND RESULTS: Liver cancer cells grown on collagen 1-coated plates showed upregulation of cholangiocytic marker expression but downregulation of hepatocytic marker expression. Three-dimensional sphere culture and Boyden chamber assay showed enhanced invasion and migration ability in collagen 1-conditioned liver cancer cells. Interaction with collagen 1 reduced liver cancer cell proliferation. RNA sequencing showed that in the liver cancer cells, collagen 1 upregulated cell cycle inhibitor expression and cell-matrix interaction, tumor migration, and angiogenesis pathways, but downregulated liver metabolic function pathways. Cholangiocytic differentiation and invasiveness induced by collagen 1 was mediated by the mitogen-activated protein kinase (MAPK) pathway, which was regulated by cell-matrix interaction-induced Src activation. Analysis of the Cancer Genome Atlas cohort showed that collagen 1 induced and suppressed genes were highly enriched in ICC and HCC, respectively. In HCC samples, collagen 1-regulated genes were strongly coexpressed and correlated with COL1A1 expression. CONCLUSIONS: Liver cancer cell-matrix interaction induces cholangiocytic differentiation and switches liver cancer cells from a proliferative to an invasive phenotype through the Src/MAPK pathway, which may partly explain the differences in the behaviors of HCC and ICC.

Paradoxical overexpression of MBNL2 in hepatocellular carcinoma inhibits tumor growth and invasion.

Pre-mRNA alternative splicing is an essential step in the process of gene expression. It provides cells with the opportunity to create various protein isoforms. Disruptions of alternative splicing are associated with various diseases, including cancer. The muscleblind-like (MBNL) protein is a splicing regulatory protein. Overexpression of MBNL proteins in embryonic stem cells promotes differentiated cell-like alternative splicing patterns. We examined the expression level of MBNL2 in 143 resected HCCs using immunohistochemistry. MBNL2 was overexpressed in 51 (35.7%) HCCs. The overexpression of MBNL2 correlated with smaller tumor size (≤ 3 cm, P = 0.0108) and low tumor stage (Stage I, P = 0.0026), indicating that MBNL2 expression was lost in the late stage of HCC development. Furthermore, patients with MBNL2-positive HCCs had a borderline better 5-year overall survival (P = 0.0579). In non-cancerous liver parenchyma, MBNL2 was stained on the Canals of Hering and hepatocytes newly derived from hepatic progenitor cells. The overexpression of MBNL2 in Hep-J5 cells suppressed proliferation, tumorsphere formation, migration, and in vitro invasion, and also reduced in vivo tumor growth in NOD/SCID mice. In contrast, MBNL2 depletion with RNA interference in Huh7 cells increased in vitro migration and invasion, but did not enhance tumor growth. These results indicate that MBNL2 is a tumor suppressor in hepatocarcinogenesis.