Enhanced chemosensitivity of p73α gene transferred into H1299 cell line ofhuman lung adenocarcinoma

Objective: To study the effects of transferred wild type p73α gene on the sensitivity to the chemotherapeutic agents and the growth of p53-null H1299 cells of human lung adenocarcinoma. Methods: The pcDNA3-HA-p73α plasmid was transferred into the cultured p53-null H1299 cells of human lung adenocarcinoma with the mediation of Dosper liposome;The cells resistant to G418 were selected. The expression of p73α gene in the cells was examined with Western blot. MTT assay was used to analyze the response of the transfected cells to cis-dichlorodiamine platinum (cDDP) and adriamycin (ADM). The rate of drug-induced apoptosis of the transfected cells was determined with flow cytometry and DNA fragmentation assay. The changes of the biological behaviors were observed with colony formation assay. Results: The transfected H1299 cells of human lung adenocarcinoma over-expressed p73α protein stably. MTT assay showed that the IC50 values of cDDP and ADM were reduced by approximately 7 fold and 130 fold respectively in the transfected cells as compared with the untransfected ones. Lower concentration of the chemotherapeutic agents ( 1.25 μmol/L of cDDP and 0.05 μmol/L of ADM)could be employed to suppress markedly the growth of the transfected H1299 cells. The apoptotic rate induced by cDDP was increased from 10.1% to 38.4% ( P ＜ 0.01 ) and that of ADM from 12.1% to 49.3 % ( P ＜ 0.01 ). The clonogenecity after the administration of chemotherapeutic agents was significantly lower in the transfected H1299 cells than in the parental cells (P ＜ 0.01). The sensitive enhancement ratios were 1.8 and 2.6 for cDDP and ADM respectively. Conclusion: The transfection of H1299 cells with wild type p73α gene results in an increase of the sensitivity of the cells to chemotherapeutic agents.