ABSTRACT
<p><b>OBJECTIVE</b>To explore the effect of PI3K p85alpha gene silencing on the 5-fluorouracil (5-FU)-induced apoptosis of colorectal cancer cells.</p><p><b>METHODS</b>The PI3K p85alpha/RNAi transfected cells (PI3K p85alpha/RNAi-LoVo) were cultured in RPMI 1640 supplemented with 10% fetal calf serum and 500 microg/ml G418. The 50% inhibitory concentration (IC50) values of 5-FU (0.000625, 0.00125, 0.005, 0.01, 0.02, 0.04, 0.08, 0.16, 0.32 micromol/ml) were evaluated by MTT assay. Mitochondrial membrane potential was detected by JC-1 fluorescence, and Western blotting was used to analyze the expression of apoptotic proteins Bcl-6 and Bim.</p><p><b>RESULTS</b>Compared with the untransfected LoVo cells, PI3K p85alpha/RNAi-LoVo showed obviously decreased IC(50) of 5-FU (P=0.000). The mitochondrial membrane potential of PI3K p85alpha/RNAi-LoVo cells was significantly lower than that of LoVo cells, suggesting that silencing PI3K p85alpha expression increased the sensitivity of LoVo cells to 5-FU. The expression of apoptotic protein Bcl-6 and Bim were significantly higher in PI3K p85alpha/RNAi-LoVo cells treated with 5-FU than LoVo cells (P=0.000).</p><p><b>CONCLUSION</b>PI3Kp85alpha gene silencing can significantly promote 5-FU-induced apoptosis of colorectal LoVo cells.</p>