[Enhancement effect of nucleotide excision repair gene xeroderma pigmentosun group a antisense RNA on sensitivity of human lung adenocarcinoma cell line A549 to cisplatin].
OBJECTIVE
Enhanced nucleotide excision repair (NER) capacity is an important mechanism of drug-resistance of tumor cells. Xeroderma pigmentosun group A (XPA) gene plays a key role in early stage of NER pathway. This study was to explore correlation between down-regulation of XPA gene induced by antisense RNA transfection and sensitivity of human lung adenocarcinoma cell line A549 to cisplatin.


METHODS
A549 cells were stably transfected with XPA antisense RNA. Positive cell clones were selected by limiting dilution. Northern blot and Western blot were applied to evaluate mRNA and protein levels of XPA in positive cell clones. Sensitivity of A549 cells to cisplatin was evaluated by MTT assay. Host cell reactivation (HCR) assay was used to assess NER capacity of cisplatin-damaged A549 cells.


RESULTS
Six positive cell clones, AS1-AS6, were obtained, mRNA and protein levels of XPA were significantly decreased in AS3-AS6 cells. In dose-dependent experiment, the 50% inhibitory concentrations (IC(50)) of cisplatin to parental A549 cells and AS1-AS6 cells were 8.1, 7.6, 4.7, 3.2, 1.9, 2.8, and 4.1 mug/ml, respectively. Sensitivities of AS3-AS6 cells were significantly higher than that of parental A549 cells (F = 9.75, 9.14, 7.39, 8.91u P = 0.005, 0.006, 0.012, 0.006). In addition, mRNA level of XPA was positively correlated with IC(50) of cisplatin (r = 0.927, P = 0.003). Time-effect experiment also showed increases of sensitivity to cisplatin in AS3-AS6 cells. HCR assay showed that NER capacities of AS3-AS6 cells were reduced. When treated with 40, 200, and 1 000 ng/ml of cisplatin, mRNA levels of XPA were positively correlated with cellular NER capacities (r = 0.854, 0.696, 0.858u P = 0.014, 0.082, 0.013).


CONCLUSIONS
The targeted inhibition of XPA by antisense strategy can significantly decrease mRNA level of XPA, reduce cellular NER capacity, and sensitize lung cancer cells to cisplatin.
Fan
Wei
W
Institute of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, P. R. China.
Zhang
Hai-Long
HL
Wu
Xiao-Ming
XM
D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D000970:Antineoplastic Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D004260:DNA Repair; D019008:Drug Resistance, Neoplasm; D006801:Humans; D020128:Inhibitory Concentration 50; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology*; D016372:RNA, Antisense / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014162:Transfection; D051760:Xeroderma Pigmentosum Group A Protein / Q000096:biosynthesis / Q000235:genetics*
D000970:Antineoplastic Agents; D016372:RNA, Antisense; D012333:RNA, Messenger; D051760:Xeroderma Pigmentosum Group A Protein; D002945:Cisplatin