Genome-wide analysis of gene expression in human intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma is a neoplasm arising in the liver, and its incidence is increasing in Japan as well as in Western countries. Prognosis of patients with this type of tumor remains unsatisfactory because no effective chemotherapeutic drugs are available, we have no sensitive tumor markers to detect this tumor in its early stage, and it is difficult to identify a high-risk group for the disease. To clarify the molecular mechanism of tumorigenesis and identify molecular targets for diagnosis and treatment, we analyzed global gene-expression profiles of 25 intrahepatic cholangiocarcinomas using tumor cell populations purified by laser microbeam microdissection and a cDNA microarray containing 27,648 genes. We identified 52 genes that were commonly upregulated and 421 that were downregulated in intrahepatic cholangiocarcinomas compared with noncancerous biliary epithelial cells. From the 52 upregulated genes, we selected P-cadherin and survivin for further investigation and corroborated enhanced expression of their products in cancer tissues by immunohistochemical staining. Furthermore, comparison between tumors with lymph node metastasis and those without metastasis identified 30 genes that were associated with lymph node involvement. In conclusion, these data should be helpful for a better understanding of the tumorigenesis of intrahepatic cholangiocarcinoma and should contribute to the development of diagnostic and therapeutic strategies for this type of tumor.