title: Combination effects of paclitaxel with signaling inhibitors in endometrial cancer cells.
abstract: This study was conducted to evaluate and compare molecular and cellular effects of paclitaxel in combination with epidermoid growth factor receptor (EGFR) or/and mammalian target of rapamycin( mTOR) inhibitors with two endometrial cancer lines HEC-1A and Ishikawa. Treatment was with the EGFR inhibitor RG14620, the mTOR inhibitor rapamycin, and the conventional cytotoxic drug paclitaxel, alone or in combination. The 50% inhibitory concentration (IC50) and cell viability were determined by the MTT assay. Multiple drug effect/ combination indexes (CI) analysis was applied to assess interactions between paclitaxel and the two inhibitors. Apoptosis and cell cycling were evaluated by flow cytometry analysis. Western blotting was performed to evaluate the related protein alteration in PI3K/AKT signaling pathway. RG14620, rapamycin and paclitaxel showed obvious dose-dependent growth inhibition with time. The IC50 of paclitaxel at 24 hours decreased significantly when pretreated with low doses of RG14620 and Rapamycin alone or in combination. Moreover, combination index (CI) of paclitaxel with each inhibitor was larger than 1, indicating a synergistic effect between pairs of drugs in these two cell lines. FACS analysis showed the cell apoptosis rate increased with a synergistic effect. On Western blotting, activation of PI3K/AKT pathway was detected in both two cell lines in the control case. When paclitaxel was used as a single-agent or in combinations, the protein expression of PI3K/AKT pathway totally abated, especially in HEC-1A cells, suggesting a role in chemoresistance. The combination of three drugs induced the greatest over-expression of caspase-3. Combining targeted inhibitors with cytotoxic chemotherapy appears to be a promising strategy for the effective treatment of endometrial cancer which merits further clinical investigation.
authors.affiliation: Department of Obstetrics and Gynecology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Chengfang
authors.initials: C
authors.lastname: Xu
authors.forename: Xiaomao
authors.initials: X
authors.lastname: Li
authors.forename: Tian
authors.initials: T
authors.lastname: Li
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Wang
authors.forename: Yuebo
authors.initials: Y
authors.lastname: Yang
authors.forename: Lan
authors.initials: L
authors.lastname: Xiao
authors.forename: Huimin
authors.initials: H
authors.lastname: Shen
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D016889:Endometrial Neoplasms / Q000188:drug therapy*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D005260:Female; D006801:Humans; D020128:Inhibitory Concentration 50; D017239:Paclitaxel / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors*
chemical_list: D000970:Antineoplastic Agents; D053148:Caspase 3; D004791:Enzyme Inhibitors; D066246:ErbB Receptors; D017239:Paclitaxel; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D020123:Sirolimus; D058570:TOR Serine-Threonine Kinases; C505407:CASP3 protein, human