| Summary: | 碩士 === 中山醫學大學 === 醫學研究所 === 103 === Chemotherapy is the common treatment for lung cancer patients. The development of drug resistance is the most important cause of treatment failure. When cancer resistant to chemotheraputic drugs, it is commonly developed cross-resistance to other anti-cancer drugs. In previous experiments, we have used docetaxel to select A549 cells and two sublines of A549/D16 and A549/D32 have been established. We have found these two sublines were more sensitive to Alimta than the parental A549 cells. Therefore, we plan to further characterize the mechanism of Alimta sensitivity in these two A549/D16 and A549/D32 cells. We used MTT assay, Clonogenic assay, Western blot to determine the Alimta sensitivity and protein expression in these docetaxel-resistant cells. The data showed that thymidylate synthase (TS), dihydrofolate reductase (DHFR) and gamma-glutamyl hydrolase (GGH) protein expression were downregulated. We further showed that the docetaxel resistant lung cancer line with low TS determined higher Alimta sensitivity. When TS was overexpressed by transfection resulted in lower Alimta sensitivity. In addition, we also found that when A549 cells treated with docetaxel, the upregulated p53 was associated with a decline in the TS. The data indicated that p53 may downregulate TS expression. The genes of p53 and TS that mediate Alimta sensitivity in docetaxel-resistant A549 cells could be used as a biomarker for the second line chemotherapy. Our study may benefit those docetaxel-resistant lung cancer patients to have a tailed-made anti-cancer therapy.
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