[Effect and mechanism of DNMT inhibitor on the reversal of multidrug resistance in human colon cancer cell line sw620/L-OHP].
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.
Abdominal Oncology Department, West China Hospital, Sichuan University, Chengdu 610041, China.
Qian
Q
Deng
Zhi-ping
ZP
Li
Chun-mei
CM
Huang
Zhen
Z
Liu
Ren-ming
RM
Zhong
Ai-jun
AJ
Li
Feng
F
Bi
Qiu-lin
QL
Tang
D018435:ATP Binding Cassette Transporter, Subfamily B / Q000378:metabolism; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D045744:Cell Line, Tumor / Q000187:drug effects; D003110:Colonic Neoplasms / Q000235:genetics* / Q000473:pathology; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors*; D000077209:Decitabine; D018432:Drug Resistance, Multiple / Q000187:drug effects* / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism
D018435:ATP Binding Cassette Transporter, Subfamily B; D001374:Azacitidine; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D015254:DNA Modification Methylases; D000077209:Decitabine; D008565:Membrane Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011518:Proto-Oncogene Proteins; C090121:BNIP3 protein, human