Distinct miRNA signatures associate with subtypes of cholangiocarcinoma from infection with the tumourigenic liver fluke Opisthorchis viverrini.

BACKGROUND & AIMS: Intrahepatic cholangiocarcinoma (ICC) is a significant public health problem in East Asia, where it is strongly associated with chronic infection by the food-borne parasite Opisthorchis viverrini (OV). We report the first comprehensive miRNA expression profiling by microarray of the most common histologic grades and subtypes of ICC: well differentiated, moderately differentiated, and papillary ICC. METHODS: MicroRNA expression profiles from FFPE were compared among the following: ICC tumour tissue (n = 16), non-tumour tissue distally macrodissected from the same ICC tumour block (n = 15), and normal tissue (n = 13) from individuals undergoing gastric bypass surgery. A panel of deregulated miRNAs was validated by qPCR. RESULTS: Each histologic grade and subtype of ICC displayed a distinct miRNA profile, with no cohort of miRNAs emerging as commonly deregulated. Moderately differentiated ICC showed the greatest miRNA deregulation in quantity and magnitude, followed by the papillary subtype, and then well differentiated ICC. Moreover, when ICC tumour tissues were compared to adjacent non-tumour tissue, similar miRNA dysregulation profiles were observed. CONCLUSIONS: We show that common histologic grades and subtypes of ICC have distinct miRNA profiles. As histological grade and subtypes are associated with ICC aggressiveness, these profiles could be used to enhance the early detection and improve the personalised treatment for ICC. These findings also suggest the involvement of specific miRNAs during ICC tumour progression and differentiation. We plan to use these insights to (a) detect these profiles in circulation and (b) conduct functional analyses to decipher the roles of miRNAs in ICC tumour differentiation.

The miRNAome of Opisthorchis viverrini induced intrahepatic cholangiocarcinoma.

Intrahepatic cholangiocarcinoma (ICC) is an aggressive cancer, arising in the biliary ducts that extend into the liver. The highest incidence of ICC occurs in Southeast Asia, particularly in the Mekong River Basin countries of Thailand, Laos, Cambodia, and Vietnam, where it is strongly associated with chronic infection by the food-borne liver fluke Opisthorchis viverrini (OV), one of only three eukaryote pathogens considered Group one carcinogens. Intrahepatic cholangiocarcinoma is usually diagnosed at an advanced stage, with a poor prognosis and survival often less than 24 months. Hence, biomarkers that enable the early detection of ICC would be desirable and have a potentially important impact on the public health in the resource-poor regions where this cancer is most prevalent. As microRNAs (miRNAs) remain well preserved after formalin fixation, there is much interest in developing them as biomarkers that can be investigated using tumor biopsy samples preserved in formalin fixed paraffin embedded (FFPE) tumor blocks. Recently, we reported the first comprehensive profiling of tissue-based miRNA expression using FFPE from the three most common subtypes of OV-induced ICC tumors: moderately differentiated ICC, papillary ICC, and well-differentiated ICC. We observed that each subtype of OV-induced ICC exhibited a distinct miRNA profile, which suggested the involvement of specific sets of miRNAs in the progression of this cancer. In addition, non-tumor tissue adjacent to ICC tumor tissue on the same FFPE block shared a similar miRNA dysregulation profile with the tumor tissue than with normal (non-tumor) liver tissue (individuals without ICC or OV infection). Herein, we provide a detailed description of the microarray analysis procedures used to derive these findings.