Induction Mechanisms of Cholangiocarcinoma by Liver Fluke

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Infection rate of Opisthorchis viverrini (Ov) in snail and fish were surveyed, at 2 lakes located in Northeast Thailand. No Ov cercariae were detected in snails. Whereas Ov metacercariae were detected in cyprinoid fish caught at both lakes.These metacercariae were given to hamster to induce cholangiocell carcinomas.Chemical carcinogen (DMN) induced cholangiocell carcinomas in 30% of the animals at 23 weeks after the termination of the treatment. An infection with Ov promoted the carcinogenesis to 100%. The preimmunization of the animals by crude extracts of Ov influenced the cancer development variously, regulating and progressing. Ov infection alone resulted in a variety of pathological changes such as dilatation of bile duct, bile ductule prolifertation, and liver cirrhosis but not cancer. Oncofetal type of extracellular matrix tenascin was examined by immunohistochemistry. The positive staining was found in connective tissues surrounding the dilatated ducts and the stroma of cancers, and strongly in the stroma flame of necrotic cancer nodules.Nineteen Thai cases of cholangiocellular carcinoma (CCC) and 23 Japanese cases of CCC were compared for clinicopathological and biological features. A review of histological type revealed poorly differentiated and mucinous adenocarcinoma to be somewhat more prevalent in the Thai cases, and peribiliary fibrosis and adenomatous hyperplasia were found to be much more frequent in the Thai cases in noncancerous area of the liver. No significant differences in expression of p53 protein or c-erbB.2 protein were found between the two series, but proliferative activity evaluated by mean MIB1 L.I.was significantly higher in the Thai cases.Nucleotide sequence of ITS2 in Ov ribosomal DNA was determined. They were compared among Ov taken from three districts (Chonnabot, Chaiyaphum and Kalasin) in northeast Thailand but there was no difference among them.