Mechanism of suppression on proliferation of QGY cell by oxaliplatin

Abstract

Objective:To observe the effects of oxaliplatin(L-OHP) on proliferation of human hepatoma cell line QGY in vitro and to investigate the mechanism. Methods: The inhibition of proliferation in QGY cell was assayed by MTT-test. Morphologic changes were observed under light microscope and electronic microscope. Distribution of cell cycle and apoptosis were analyzed using flow cytometry. The expressions of cell cycle proteins and apoptosis-associated proteins were detected with immuno-histochemical technique. Results: Oxaliplatin could inhibit the proliferation of QGY cells and the inhibition depended on the exposure time and dose. The cells showed morphologic changes of the early stage of apoptosis under the light microscope: the shrunk round cells, condensed cytoplasma and pycnosis of nucleus. Apoptotic cells and apoptotic body could be found under the transmission electronic microscope. The analysis of cell cycle indicated that oxaliplatin blocked cells at S and G 2 /M phases and the cells of G 0 /G l phase reduced. When treated with oxaliplatin for 72h, the expressions of cyclin A and Bax were up-regulated, mutant type P53, Bcl-2 and Myc were down-regulated, and Fas was not changed. Conclusion: Oxaliplatin could inhibit the proliferation of the hepatoma cell lines. Cells were blocked at S and G 2 /M phases. The apoptosis was related to the up-regulation of Bax and down-regulation of mutant type P53, Bcl-2 and Myc. Oxaliplatin could not induce apoptosis through the Fas pathway. Key words：Oxaliplatin；Hepatocellular carcinoma；ProliferationOxaliplatin (L-OHP) [chemical name: L-cis-1, 2-diaminocyclohexanemalonato platinum (II)] is one of the third generation platin compounds. Preclinical studies have demonstrated that this drug suppresses many kinds of human and murine tumor cells, and that various cisplatin-resistant tumor cell strains exhibit no cross-resistance to it. Clinical data demonstrate that in the treatment of many kinds of tumors, oxaliplatin, used alone or in combination with other drugs, exhibits good therapeutic effect and tolerance, few toxic or side effects, high chemotherapeutic index, and wide margin ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ of safety [1][2][3][4][5][6] . Nevertheless, in vivo and in vitro effects of oxaliplatin in human liver tumor has rarely been reported. In this study, we investigated the effect of oxaliplatin on in vitro proliferation of QGY cells (a human hepatocellular carcinoma (HCC) cell strain) to provide theoretical basis for the clinical treatment of HCC with oxaliplatin. MATERIALS AND METHODS Cell Line and Culture ConditionsQGY cells were provided by the Institute of Hepatitis Viral of the Second Affiliated Hospital, Chongqing University of Medical Sciences. QGY cells were cultured in RPMI1640 medium containing 10% calf serum in air with 5%CO 2 at 37°C.