[Effect of p73 gene on chemosensitivity of human lung adenocarcinoma cells H1299]

Recent studies have shown that wild-type p53 gene can enhance the chemosensitivity of the majority of non-small cell lung cancers. p73 gene and its homologue p53 gene have significant sequence and functional similarities. This study was designed to investigate the effect of p73 gene on chemosensitivity of human lung adenocarcinoma cells H1299.

The pcDNA3-HA-p73alpha plasmid were transferred into in vitro cultured human lung adenocarcinoma cell line H1299 with Dosper. The p73alpha positive cells which were resistant to G418 were selected out. The expression of exogenous P73alpha protein were examined by Western blot analysis. MTT assay were used to analyze the response of transfected cells to cisplatin (cDDP),adriamycin (ADM). The drug-induced apoptosis of transfected cells was measured by flow cytometry and TUNEL technique. The biological behavior changes of the cells were observed by colony formation assay.

The transfected lung adenocarcinoma cell line H1299 overexpressed P73alpha protein stably. MTT assay showed that the IC(50) values for cDDP and ADM were reduced to approximate 86.2% and 99.2% in the transfected cells compared with the untransfected cells, respectively. The low concentration of chemotherapeutic drugs (1.25 micromol/L cDDP or 0.05 micromol/L ADM) without inhibition essentially suppressed the growth of the transfected cells markedly. The cDDP-induced apoptosis rate increased from 10.1% to 38.4%(P< 0.01). The ADM-induced apoptosis rate increased from 12.1% to 49.3%(P< 0.01). Colony-formation assays showed that the colony number in transfected cells was decreased significantly by chemotherapeutic drugs compared with parental cells(P< 0.01). The sensitive enhancement ratios for cDDP or ADM were 1.8 and 2.6, respectively.

p73 gene was capable of enhancing the sensitivity of H1299 cells to chemotherapeutic drugs such as cDDP and ADM, and the increased sensitivity was associated with the induction of apoptosis undepend p53 gene. It suggests the possibility of using p73 gene combined with anticancer agents to improve the effectiveness of chemotherapy.