P73 Gene Overexpression Induces Apoptosis and Increases Chemosensitivity in Human Lung Adenocarcinoma Cells A549

Abstract

Objective: As some NSCLC harbor wild-type p53, it would be important to override the resistance mechanism due to wild-type p53 in NSCLC gene therapy. The p53 family member p73 has significant homology to p53 tumor suppressor. The aim of this work was to observe the degree of apoptosis and chemosensitivity of p53-resistant human lung adenocarcinoma A549 cells following wild-type p73 gene transfer alone or combined with chemotherapetutic agents. Methods: The pcDNA3-HA-p53 or pcDNA3-HA-p73αplasmids were transferred into in vitro cultured human lung adenocarcinoma cell line A549 with Dosper. The cells resistant G418 were selected. The expressions of exogenous p53 or p73α gene were examined by Western blot. MTT assay were used to analyze the response of transfected cells to Cis-dichlorodiamine platinum(CDDP) or adriamycin(ADM). The drug-induced apoptosis of transfected cells was measured by flow cytometry assay, TUNEL technique and DNA fragmentation. The biological behavior change of cells was observed by colony formation assay. Results: The transfected lung adenocarcinoma cells A549 could overexpress P53 or P73αprotein stably. We found that p73, but not p53, is capable of sensitizing A549 cells to apoptosis induced by CDDP or ADM. Lower concentration of chemotherapeutic agents without inhibition essentially can suppress growth of p73 transfected cells markedly. p73 gene transfer combined with CDDP or ADM was shown to be even more effective in suppressing growth in A549 cell. Conclusions: Exogenous p73 gene was capable of enhancing the sensitivity of wild-type p53 human lung adenocarcionoma cells A549 to chemotherapeutic agents. It suggests the possibility of using p73 gene to improve p53-resistant tumor treatment. The combined treatment with p73 gene and chemotherapy could be an attractive strategy for inhibiting progression of NSCLC through effective induction of apoptosis.