Japanese Encephalitis Virus NS3 Protein induced HeLa Cell Apoptosis by Decreasing STAT3 Signal and Survivin Expression

• Main Authors: Hsieh Meng-Ying, 謝萌瑛
• Other Authors: 江漢聲
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/32894492337569629377

碩士 === 輔仁大學 === 基礎醫學研究所碩士班 === 95 === Non-structural protein, NS3 fragment derived from Japanese encephalitis virus (JEV), are cytotoxic to a tumor cell line, HeLa cells, and induced them apoptosis via caspase cascade in our previous works. In this study, a pCR-GFP-NS3 plasmid was constructed and transfected to HeLa cells and HEK-293 cells, to clarify whether JEV NS3 protein induced cancer cells apoptosis involves STAT3 and Survivin signaling pathway but not to affect the normal cells, because of cell apoptotic pathway involves significantly these proteins expressions signaling. Survivin, a member of the inhibitor of apoptosis protein (IAP) family, is frequently over-expressed in cancer cells, but barely detected in adult quiescent tissues. The STAT3 protein is constitutively activated in many human cancer cells, and aberrant STAT3 signaling expression is implicated as an important process in malignancy. Our preliminary data showed that NS3 protein induced reductions of both STAT3 and Survivin protein expressions, however, RT-PCR results showed that gene expression of Survivin was down-regulated, but not STAT3. These results both in cancer cells but not in the normal type indicated that the NS3-induced STAT3 protein reduction through a non-gene regulatory pathway. We suppose that the decreased gene and protein expressions of Survivin could be regulated by the expression of STAT3 in cancer cells. The expressions of STAT3 and Survivin in the transfected HeLa cells detected by immuno-fluorescence showed reductions as well as previous results, and the localizations of them were altered. Afterward, the Real-Time RT-PCR results showed because of the Sonic-Hedgehog (SHH) pathway activated to protect the normal cells not to affect by NS3, but the cancer cells losed this pathway. The PARP, pAKT , and ELISA Brdu analysis not only confirmed these phenomenons but also indicated the JEV NS3 protein can induce cancer cells, Hela, apoptosis and inhibit them proliferation, but not to occur on the normal cells, HEK-293, because of SHH pathway to protect its self. These data further confirmed our proposal that the associations among the Survivin, STAT3 and NS3 proteins occurred and defined the mechanisms of NS3-induced cancer cells apoptosis but not the normal type. In addition to our other experiment data on various tumor cells, characterized as a candidate for anti-tumor agent.