Promotion of Cancer Stem-Like Cell Properties in Hepatitis C Virus-Infected Hepatocytes.

UNLABELLED: We have previously reported that hepatitis C virus (HCV) infection of primary human hepatocytes (PHH) induces the epithelial mesenchymal transition (EMT) state and extends hepatocyte life span (S. K. Bose, K. Meyer, A. M. Di Bisceglie, R. B. Ray, and R. Ray, J Virol 86:13621-13628, 2012, http://dx.doi.org/10.1128/JVI.02016-12). These hepatocytes displayed sphere formation on ultralow binding plates and survived for more than 12 weeks. The sphere-forming hepatocytes expressed a number of cancer stem-like cell (CSC) markers, including high levels of the stem cell factor receptor c-Kit. The c-Kit receptor is regarded as one of the CSC markers in hepatocellular carcinoma (HCC). Analysis of c-Kit mRNA displayed a significant increase in the liver biopsy specimens of chronically HCV-infected patients. We also found c-Kit is highly expressed in transformed human hepatocytes (THH) infected in vitro with cell culture-grown HCV genotype 2a. Further studies suggested that HCV core protein significantly upregulates c-Kit expression at the transcriptional level. HCV infection of THH led to a significant increase in the number of spheres displayed on ultralow binding plates and in enhanced EMT and CSC markers and tumor growth in immunodeficient mice. The use of imatinib or dasatinib as a c-Kit inhibitor reduced the level of sphere-forming cells in culture. The sphere-forming cells were sensitive to treatment with sorafenib, a multikinase inhibitor, that is used for HCC treatment. Further, stattic, an inhibitor of the Stat3 molecule, induced sphere-forming cell death. A combination of sorafenib and stattic had a significantly stronger effect, leading to cell death. These results suggested that HCV infection potentiates CSC generation, and selected drugs can be targeted to efficiently inhibit cell growth. IMPORTANCE: HCV infection may develop into HCC as an end-stage liver disease. We focused on understanding the mechanism for the risk of HCC from chronic HCV infection and identified targets for treatment. HCV-infected primary and transformed human hepatocytes (PHH or THH) generated CSC. HCV-induced spheres were highly sensitive to cell death from sorafenib and stattic treatment. Thus, our study is highly significant for HCV-associated HCC, with the potential for developing a target-specific strategy for improved therapies.

Dasatinib induces endothelial-to-mesenchymal transition in human vascular-endothelial cells: counteracted by cotreatment with bosutinib.

Adverse vascular events have become a serious clinical problem in chronic myeloid leukemia (CML) patients who receive certain BCR/ABL1 tyrosine kinase inhibitors (TKIs). Studies have shown that endothelial-to-mesenchymal transition (EndMT) can contribute to various vascular diseases. We investigated the effects of TKIs on the development of EndMT in human vascular-endothelial cells (VECs). Exposure of VECs to dasatinib, but not to other TKIs, produced a significant increase in the formation of spindle-shaped cells. This effect was accompanied by a significant increase in expression of the EndMT inducer transforming growth factor-ß (TGF-ß) and mesenchymal markers vimentin, smooth muscle alpha-actin, and fibronectin, as well as a significant decrease in expression of vascular-endothelial markers CD31 and VE-cadherin attributable at least in part to activation of ERK signaling. Inhibitors of TGF-ß and ERK partially attenuated dasatinib-induced EndMT. Interestingly, bosutinib efficiently counteracted dasatinib-induced EndMT and attenuated dasatinib-induced phosphorylation of ERK. Taken together, these results show that dasatinib induces EndMT, which might contribute to the development of vascular toxicity, such as the pulmonary hypertension observed in CML patients receiving dasatinib. Bosutinib could play a distinct role in protecting VECs from EndMT.