KRAS and PIK3CA but not BRAF genes are frequently mutated in Chinese cholangiocarcinoma patients

Cholangiocarcinoma (CCA) is a rare but lethal malignancy arising from the biliary tract epithelium. It has a poor prognosis largely due to the difficulties of early diagnosis and the lack of effective therapies. It is thus imperative to develop new and effective treatments for CCA, which depends heavily on the mechanistic understanding of the disease. Previous studies have suggested that somatic mutations in KRAS, BRAF, and PIK3CA genes are frequently found in several types of human cancers including colon, breast, and lung carcinomas as well as CCA. Yet, the frequency and the involvement of these oncogenic mutations in CCA in Chinese population have not been investigated. In this study, we evaluated the hotspot mutations of KRAS, BRAF, and PIK3CA genes in 34 Chinese CCA patients. Sequencing analysis revealed 13 (38.2%) and 11 (32.4%) patients bearing KRAS and PIK3CA mutations, in which two (5.9%) of them harbored both KRAS and PIK3CA mutations. Surprisingly, no BRAF mutation was detected in all 34 CCA samples. Our findings indicate that somatic mutations in KRAS and PIK3CA but not BRAF oncogenes are closely associated with the development of CCA in Chinese population and provide new potential targets for future therapeutic treatments of the disease.