Growth inhibitory effect of beta-eudesmol on cholangiocarcinoma cells is associated with suppression of heme oxygenase-1 production and STAT3 phosphorylation

<p>Cholangiocarcinoma (CCA) is a progressively fatal form of cancer generally arising from malignant transformation of hepatic biliary cholangiocytes. To investigate in vitro growth inhibitory activities of bioactive sesquiterpenoid beta-eudesmol in relation to its underlying potential effects on heme oxygenase-1 (HO-1) production and STAT3 phosphorylation in CCA cells. Human cholangiocarcinoma (CL-6) and normal human embryonic fibroblast (OUMS) cells were used in this study. Cell cytotoxicity was evaluated using MTT assay. Cell culture morphology was visualized using light microscopy. Nuclear morphology was determined using DAPI staining and fluorescence imaging. Anti-proliferative effect was evaluated using colony forming assay. Cell migration was studied using wound healing assay. Relative fold of mRNA expressions were evaluated using real-time PCR. Protein expressions were determined using western blot. Beta-eudesmol treatment exhibited selective cytotoxicity towards CL-6 as compared to OUMS cells. The compound treatment significantly suppressed colony forming ability of CL-6 cells. In addition, it also induced nuclear fragmentation of CL-6 cells. The compound pretreatment significantly decreased wound healing ability of CL-6 cells in the presence or absence of interlukin-6 stimulation. Beta-eudesmol treatment significantly suppressed mRNA expression of multiple genes associated with cell proliferation, HO-1 enzyme production and STAT3 activation. The compound treatment resulted in decreased expression of HO-1 and significantly suppressed STAT3 phosphorylation in CL-6 cells. Our results suggest that Beta-eudesmol exerts potent growth inhibitory activity on cholangiocarcinoma cells which might be linked to its inhibitory effect on HO-1 production and STAT3 phosphorylation.</p>