Genome-wide expression patterns associated with oncogenesis and sarcomatous transdifferentation of cholangiocarcinoma

Min-A Seol,Dae-Ghon Kim,Eun-Kyung Ahn,Sun-Hee Leem,Mi-Jin Lee,Xiang-Dan Cui,In-Hee Kim,Baik-Hwan Cho,Goung-Ran Yu,In-Sun Chu

doi:10.1186/1471-2407-11-78

Abstract

BackgroundThe molecular mechanisms of CC (cholangiocarcinoma) oncogenesis and progression are poorly understood. This study aimed to determine the genome-wide expression of genes related to CC oncogenesis and sarcomatous transdifferentiation.MethodsGenes that were differentially expressed between CC cell lines or tissues and cultured normal biliary epithelial (NBE) cells were identified using DNA microarray technology. Expressions were validated in human CC tissues and cells.ResultsUsing unsupervised hierarchical clustering analysis of the cell line and tissue samples, we identified a set of 342 commonly regulated (>2-fold change) genes. Of these, 53, including tumor-related genes, were upregulated, and 289, including tumor suppressor genes, were downregulated (<0.5 fold change). Expression of SPP1, EFNB2, E2F2, IRX3, PTTG1, PPARγ, KRT17, UCHL1, IGFBP7 and SPARC proteins was immunohistochemically verified in human and hamster CC tissues. Additional unsupervised hierarchical clustering analysis of sarcomatoid CC cells compared to three adenocarcinomatous CC cell lines revealed 292 differentially upregulated genes (>4-fold change), and 267 differentially downregulated genes (<0.25 fold change). The expression of 12 proteins was validated in the CC cell lines by immunoblot analysis and immunohistochemical staining. Of the proteins analyzed, we found upregulation of the expression of the epithelial-mesenchymal transition (EMT)-related proteins VIM and TWIST1, and restoration of the methylation-silenced proteins LDHB, BNIP3, UCHL1, and NPTX2 during sarcomatoid transdifferentiation of CC.ConclusionThe deregulation of oncogenes, tumor suppressor genes, and methylation-related genes may be useful in identifying molecular targets for CC diagnosis and prognosis.

Highlights

The molecular mechanisms of CC oncogenesis and progression are poorly understood
Using unsupervised hierarchical clustering analysis, we found that the SPP1, EFNB2, and E2F genes were commonly upregulated in both cell and tissue samples
SPP1 is a ligand of CD44 that binds to aV-containing integrins and is important in malignant cell attachment and tumor invasion [43]

Summary

Introduction

The molecular mechanisms of CC (cholangiocarcinoma) oncogenesis and progression are poorly understood. CC accounts for approximately 15% of the total liver cancer cases worldwide, and its incidence is rising [1,2]. 70% of CC patients have an occult metastasis or advanced local disease that precludes curative resection. Of candidates for curative resection, 30% develop recurrent disease at the anastomotic site or within the intrahepatic biliary tree, and succumb to disease progression or cholangitis [5]. Established risk factors for ductal cholangiocarcinomas include primary sclerosing cholangitis, infection with Clonorchis sinensis or Opisthorchis viverrini (liver flukes), Calori’s disease, congenital choledochal cysts, and chronic intrahepatic lithiasis [6].

Objectives

Methods

Results

Discussion

Conclusion