Mutational analysis on the function of the SWAP-70 PH domain |
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| Authors: | Isamu Wakamatsu Sayoko Ihara Yasuhisa Fukui |
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| Institution: | (1) Center of General Education, Central Taiwan University of Science & Technology, Taichung, 406, Taiwan;(2) Department of Surgery, Dacha Lee's General Hospital, Dacha, Taiwan;(3) Department of Surgery, Taichung Veterans General Hospital, Taichung, Taiwan;(4) School of Physical Therapy, Chung-Shan Medical University, Taichung, Taiwan;(5) Institute of Biochemistry and Biotechnology, Chung-Shan Medical University, Taichung, Taiwan;(6) Institute of Toxicology, Chung-Shan Medical University, Taichung, Taiwan;(7) Department of Veterinary Medicine, National Chung-Hsing University, Taichung, Taiwan;(8) Department of Internal Medicine and Microb iology and Immunology, Chung-Shan Medical University, Taichung, Taiwan;(9) Armed Forces Taichung General Hospital, Taichung, Taiwan, ROC;(10) Department of Biological Science and Technology, Graduate Institute of Chinese Medical Science, China Medical University, No. 91, Hsueh-Shih Road, Taichung, 404, Taiwan |
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| Abstract: | Hepatocellular carcinoma (HCC), the major manifestation of primary liver cancer, is one of the most frequent and malignant cancers worldwide, especially in Taiwan. Estrogen receptors (ERs) have been reported to play either a proliferation- or apoptosis-enhancing role in the differentiation of cancers, including HCC. In a previous experiment, we showed that transient overexpressed estrogen receptor-α induced early stage HCC cell line Hep 3B cell apoptosis by increasing the hTNF-α gene expression in a ligand-independent manner. To further clarify if the apoptotic effect occurs in poorly differentiated HCC cell line, HA22T, and elucidate the roles of ERs and TNF-α, DNA fragmentation and caspase activity were measured in late stage HCC cell line, HA22T, by measuring the expression of hER-α and hER-β using a Tetracycline-induciable system (Tet-on). Increased DNA fragmentation and caspase-3 activity were found in hERβ-overexpressed HA22T cells treated with estrogen (10−8 M) but not in hERα-overexpressed HA22T cells. Using RT-PCR/PCR and western blotting in HA22T cells, overexpressed hER-β was also found to increase the expression of hTNF-α mRNA and induce hTNF-α-dependent luciferase activity in a ligand-dependent manner. Additionally, LPS treatment and hER-β overexpression both enhance caspase-8 activities, whereas neither hER-β nor E2 treatment affected caspase-9 activities. In addition, the overexpressed hER-β plus E2 enhanced DNA fragmentation and caspase-8 activities were only partially reduced by anti-hTNF-α (0.1ng/ml), which was possibly due to the involvement of P53 and TGF-β. Taken together, our data indicates that overexpressed hER-β but not hER-α may induce caspase-8-mediated apoptosis by increasing the hTNF-α gene expression in a ligand-dependent manner in poorly differentiated HA22T cells. (Mol Cell Biochem xxx: 1–9, 2005)Shares equally contribution Contract grant sponsor: National Science Council; Contract grant number: NSC 91-2314-B-075A-006, NSC 92-2314-B-075A-014. |
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| Keywords: | Phosphatidylinositol 3-kinase PH domain ruffling Rac translocation PtdIns(3 4 5)P3 |
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