151. Demethylation of HIN-1 reverses paclitaxel-resistance of ovarian clear cell carcinoma through the AKT-mTOR signaling pathway.
- Author
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Chih-Ming Ho, Chi-Jung Huang, Shih-Hung Huang, Shwu-Fen Chang, Wen-Fang Cheng, Ho, Chih-Ming, Huang, Chi-Jung, Huang, Shih-Hung, Chang, Shwu-Fen, and Cheng, Wen-Fang
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OVARIAN cancer treatment ,OVARIAN cancer patients ,PACLITAXEL ,DRUG resistance in cancer cells ,HYPOXIA-inducible factor 1 ,DEMETHYLATION ,PROTEIN kinase B ,HEALTH outcome assessment ,ADENOCARCINOMA ,ANIMAL experimentation ,ANTINEOPLASTIC agents ,CELL lines ,CELLULAR signal transduction ,CYTOKINES ,MICE ,OVARIAN tumors ,PROTEINS ,TRANSFERASES ,DNA methylation ,PHARMACODYNAMICS - Abstract
Background: Methylation of HIN-1 is associated with poor outcomes in patients with ovarian clear cell carcinoma (OCCC), which is regarded to be an aggressive, chemo-resistant histological subtype. This study aimed to evaluate whether 5-aza-2-deoxycytidine (5-aza-2-dC) can reverse methylation of the HIN-1 gene to restore chemo-sensitivity of OCCC and the possible mechanism.Methods: In vitro flow cytometric analysis and evaluation of caspase-3/7 activity of paclitaxel-sensitive and resistant OCCC cell lines were performed. Methylation status and expression changes of HIN-1 in the OCCC cell lines treated with 5-aza-2-dC were evaluated, and immunohistochemical staining of HIN-1 in OCCC tissues was performed. In vivo tumor growth with or without 5-aza-2-dC treatment was analyzed, and Western blotting of AKT-mTOR signaling-related molecules was performed.Results: G2-M phase arrest was absent in paclitaxel-resistant OCCC cells after treatment with the cytotoxic drug. The caspase activities of the chemo-resistant OCCC cells were lower than those of the chemo-sensitive OCCC cells when treated with paclitaxel. Methylation of HIN-1 was noted in paclitaxel-resistant OCCC cell lines and cancerous tissues. 5-aza-2-dC reversed the methylation of HIN-1, re-activated the expression of HIN-1, and then suppressed the in vivo tumor growth of paclitaxel-resistant OCCC cells. Immunoblotting revealed that phospho-AKT473 and phospho-mTOR were significantly increased in HIN-1-methylated paclitaxel-resistant OCCC cell lines. However, the expressions of phospho-AKT at Ser473 and Thr308 and phospho-mTOR decreased in the OCCC cells with a high expression of HIN-1.Conclusions: Demethylating agents can restore the HIN-1 expression in paclitaxel-resistant OCCC cells through the HIN-1-AKT-mTOR signaling pathway to inhibit tumor growth. [ABSTRACT FROM AUTHOR]- Published
- 2015
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