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Effects of a Monomer Purified from Paris Polyphylla(PP-22) on Proliferation and Apoptosis of Human Gastric Carcinoma MGC803 Cells

??OBJECTIVE To investigate the effects of a monomer purified from Paris Polyphylla(PP-22) on proliferation,apoptosis of human gastric carcinoma MGC803 cells and to study the sensitizing effect of PP-22 on the proliferation of MGC803 cells to chemotherapeutic drugs 5-fluorouracil(5-Fu) or lobaplatin. METHODS MTT assay and cell colone formation inhibitory assay were used to determine the inhibitory effect of PP-22 on human gastric carcinoma MGC803 cells.The sensitizing effects of PP-22 on MGC803 cells to chemotherapeutic drugs 5-Fu, lobaplatin were determined by MTT assay.The percentage of apoptotic cells and cell cycle distribution were determined by flow cytometry.The expression of cell apoptosis associated proteins were analyzed by Western blotting.RESULTS MTT assay showed that PP-22 inhibited gastric carcinoma MGC803 cells proliferation in dose-dependent manner (r=0.90,P<0.05), but did not inhibit the growth of normal liver L02 cells at the same concentration. Cell colony formation inhibitory assay demonstrated that cell clones decreased with the increase of drug concentrations. The chemosensitivity of 5-Fu,or lobaplatin combined with PP-22 was improved compared with PP-22 group,respectively.PI staining analysis showed that the cell cycle was arrested at S phase. Western blotting detecting showed that the expression of Caspase-9, Caspase-3 were downregulated, the anti-apoptotic protein Bcl-2 is downregulated and pro-apoptotic protein Bak upregulated.CONCLUSION PP-22 inhibits proliferation and induces apoptosis of MGC803 cells effectively and also sensitizes MGC803 cells to chemotherapeutic drugs.