Distinct Mutational Patterns of Infection and Non-Infection-Related Bile Duct Cancers Revealed by Exome Sequencing

The impact of different carcinogenic exposures on the specific patterns of somatic mutations in human tumors remains unclear. To clarify this issue, we profiled 209 cholangiocarcinomas (CCAs) from Asia and Europe, including 108 cases caused by liver fluke Opisthorchis viverrini (OV)-infection and 101 cases due to non-OV etiologies. Whole-exome (N = 15) and prevalence screening (N = 194) revealed recurrent somatic mutations in BAP1 and ARID1A, neither of which has been previously reported to be mutated in CCA. Comparisons between intrahepatic OV and non-OV CCAs demonstrated statistically significant different mutation patterns: BAP1 and IDH1/2 were more frequently mutated in non-OV CCAs, while TP53 displayed the reciprocal pattern. Functional studies demonstrated tumor suppressive roles of BAP1 and ARID1A, establishing the role of chromatin modulators in CCA pathogenesis. These findings indicate that different causative etiologies may induce distinct somatic alterations even within the same tumor type. Affymetrix SNP6 arrays were performed according to the manufacturer's directions on DNA extracted from the 15 tumors and the 15 matched normal discovery samples.