OBJECTIVE: To explore whether demethylation inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) could reverse multidrug resistance (MDR) of human colon cancer and its impacts on the expressions of Bcl-2/adenovirus E1B 19 KDa protein interacting protein 3 (BNIP3), P-glycoprotein (P-GP) and multidrug resistance-associated protein (MRP), as well as the activity of DNA methyltransferase (DNMT). METHODS: Oxaliplatin (L-OHP) resistant human colon carcinoma cells (sw620/L-OHP) and its parental cells (sw620) were used to determine the effect of 5-aza-dC. CCK-8 assay was adopted to evaluate the cytotoxicity of 5-aza-dC. Western blot was performed to observe the expressions of BNIP3, P-GP and MRP. H microassay was used to detect the activity of DNMT. RESULTS: After the addition of 1.4 micromol/L 5-aza-dC, the 50% inhibitory concentration (IC50) of L-OHP to sw620/ L-OHP cells was decreased from (0.335 +/- 0.043) microg/mL to (0.069 +/- 0.023) microg/mL, and the chemosensitivity increased 8.26 times (P < 0.001). Western blot analysis showed that the expression of BNIP3 was up-regulated by 5-aza-dC in a concentration-dependent manner (P < 0.001), and P-GP and MRP expression were also significantly changed (P < 0.05) but not in a concentration-dependent manner (P > 0.05). DNMT activity was down-regulated by 5-aza-dC in sw620/L-OHP cells (P < 0.001). CONCLUSIONS: 5-aza-dC could reversed multi drug resistance of sw620/L-OHP, which may due to the demethylation to upregulate BNIP3 expression, and inhibit the expression of resistance-associated protein P-GP and MRP further by some unknown mechanism.
OBJECTIVE: To explore whether demethylation inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) could reverse multidrug resistance (MDR) of humancolon cancer and its impacts on the expressions of Bcl-2/adenovirus E1B 19 KDa protein interacting protein 3 (BNIP3), P-glycoprotein (P-GP) and multidrug resistance-associated protein (MRP), as well as the activity of DNA methyltransferase (DNMT). METHODS:Oxaliplatin (L-OHP) resistant humancolon carcinoma cells (sw620/L-OHP) and its parental cells (sw620) were used to determine the effect of 5-aza-dC. CCK-8 assay was adopted to evaluate the cytotoxicity of 5-aza-dC. Western blot was performed to observe the expressions of BNIP3, P-GP and MRP. H microassay was used to detect the activity of DNMT. RESULTS: After the addition of 1.4 micromol/L 5-aza-dC, the 50% inhibitory concentration (IC50) of L-OHP to sw620/ L-OHP cells was decreased from (0.335 +/- 0.043) microg/mL to (0.069 +/- 0.023) microg/mL, and the chemosensitivity increased 8.26 times (P < 0.001). Western blot analysis showed that the expression of BNIP3 was up-regulated by 5-aza-dC in a concentration-dependent manner (P < 0.001), and P-GP and MRP expression were also significantly changed (P < 0.05) but not in a concentration-dependent manner (P > 0.05). DNMT activity was down-regulated by 5-aza-dC in sw620/L-OHP cells (P < 0.001). CONCLUSIONS:5-aza-dC could reversed multi drug resistance of sw620/L-OHP, which may due to the demethylation to upregulate BNIP3 expression, and inhibit the expression of resistance-associated protein P-GP and MRP further by some unknown mechanism.