| Summary: | 碩士 === 國立中興大學 === 生命科學系所 === 107 === Non-small cell lung cancer (NSCLC) often develops multiple drug resistance during chemotherapy, which has become the biggest obstacle for clinical treatment of lung cancer. Rosiglitazone (ROSI) is a PPAR-γ agonist and has been used in diabetes and cancer treatment. Cisplatin is the first line chemotherapeutic drug for cancer. Our laboratory has recently found that NSCLC cells (H460) have developed higher drug resistance to both ROSI and Cisplatin, via different working mechanisms. Autophagy is a self-eating process to degrade defect or excessive proteins or organelles to protect cell from extreme environmental changes. It has been indicated to involve in the drug resistance of many cancer cells. The role of autophagy in regulating of multidrug resistance of H460 cells was still unclear. The primary goal of the study was to know if autophagy contributes to the drug resistances of H460 cells to ROSI and cisplatin, and its application in lung cancer therapy. The specific aims of the study included: to clarify if ROSI and cisplatin act through autophagy to promote the growth (or survival) and drug resistance of H460 cells; to confirm if ROSI act through PPAR-γ to initiate the PKCδ/JNK-1/BcL-2/Beclin-1 signaling pathway to stimulate autophagy; to know if water extract of Graptopetalum paraguayense leaves (WGP) inhibits autophagy to break drug resistance of H460 cells to ROSI and cisplatin; and to clarify if rapamycin (autophagy activator) aggravates ROSI-induced autophagy to trigger the apoptosis of H460 cells. The techniques applied in the study included, the MTT assay, Western blotting, Annexin V/PI staining, DAPI staining, DiOC6 staining and EMSA. The results showed that ROSI activated the PPAR-γ/JNK-1/BcL-2/Beclin-1 signaling pathway to stimulate autophagy, which in turn promoted the growth and drug resistance of H460 cells. Cisplatin also stimulated autophagy to inhibit apoptosis of H460 cells and lead to drug resistance. Autophagy inhibitor (3-MA), PPAR-γ inhibitor (GW9662) and WGP, all inhibited autophagy to break drug resistance of H460 cells and revealed a potential to become anticancer drugs. Rapamycin-aggravated autophagy in ROSI-treated H460 cells can indeed trigger apoptosis and break drug resistance to ROSI. In overall, the major contributions of this study were to demonstrate for first time that autophagy played a critical role in the regulation of multiple drug resistance of H460 cells; GW9662 and WGP can block ROSI-activated PPAR-γ/JNK-1/BcL-2/Beclin-1 signaling pathway to server as new autophagy inhibitors; autophagy inhibition (by 3-MA, GW9662 or WGP) and excessive induction of autophagy (by rapamycin) can both break drug resistance of H460 cells to ROSI, a critical concern for anticancer drug selection; furthermore, since WGP is safe to drink and can block the anticancer drug-induced autophagy to break drug resistance of H460 cells, it may be considered to be used as an adjuvant during chemotherapy to lower down dose of the anticancer drug applied and adverse side effects.
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