| OBJECTIVE: To observe the effects of PI3K/PKB signal transduction pathway inhibitor LY294002 on the sensitivities of human gastric carcinoma to anti-cancer drugs, And its mechanism.METHODS: The sensitivities of SGC7901 and SGC7901/VCR to chemotherapeutic drug VCR were detected by MTT. The growth inhibition effects of VCR alone and VCR in combination with PI3K/PKB inhibitor LY294002 on gastric carcinoma cells were detected by in vivo and in vitro experiments. The MDR1, Bax, Bcl-2, XIAP and caspase-3 mRNA expression levels were evaluated by semi-quantitative RT-PCR, and their protein levels were detected by Immunocytochemistry. The PKB and phospho-PKB protein levels were detected by Western blot and the cell apoptosis was detected by flow cytometry and TUNEL.RESULT : 20μmol/L LY294002 enhanced the sensitivities of SGC7901 and SGC7901/VCR cells to VCR significantly (P<0.01), their corresponding IC50 decreased from (0.20±0.03) and (8.09±0.6)μg/ml to (0.05±0.006) and (1.70±0.2)μg/ml respectively, the chemosensitivity of SGC7901 and SGC7901/VCR cells to VCR were increased to 4.00 and 4.76 folds, respectively; The mRNA and protein levels of MDR1, Bcl-2 and XIAP were depressed by LY294002 obviously, but the levels of Bax and caspase-3 were enhanced at the same time. There was obvious reduction in phospho-PKB levels following exposure to LY294002, but no change in PKB levels in either cell line. When treated by LY294002 combined with VCR, the apoptosis ratios of both SGC7901 and SGC7901/VCR cells were much higher than that of VCR alone (P<0.01). Further more, It enhanced the growth inhibition effect of VCR on transplanted gastric carcinoma in nude mice.CONCLUSION: PI3K / PKB signal transduction pathway inhibitor LY294002 can improve the chemotherapeutic sensitivities of human gastric carcinoma. the mechanism of which may be through cutting down MDR1 expression levels and regulating expression of apoptosis related genes, such as Bax,Bcl-2,XIAP and caspase-3.
|
PDF Full Text Request