[Effects of adenosine on hMLH1 methylation of human colorectal cancer cells]

To explore the effects of adenosine on hMLH1 methylation of human colorectal cancer cells.

The SW480 cells were treated with adenosine at the concentrations of 0, 1.5, 3.0, 4.5 mmol/L for 72 h. The hMLH1 methylation levels of CpG islands were detected by bisulfite sequencing polymerase chain reaction (BSP), hMLH1 mRNA expression levels by reverse transcription-polymerase chain reaction (RT-PCR), the expression levels of hMLH1 protein by Western blot and the apoptotic rates by flow cytometry (FCM). The cells were treated with adenosine at the concentrations of 0, 1.5, 3.0, 4.5 mmol/L for 24, 48, 72, 96 h. And their proliferation rates were detected by methyl thiazolyl tetrazolium (MTT).

After a 72 h treatment of adenosine, the hMLH1 promoter methylation levels of 1.5, 3.0 and 4.5 mmol/L groups were 65% ± 4%, 45% ± 11% and 16% ± 4% respectively and were all significantly lower than that of the control group (80% ± 4%, all P < 0.01). The mRNA expression levels, hMLH1 protein expression levels and apoptotic rates were all significantly higher than that of the control group (0.230 ± 0.032, 0.359 ± 0.029 and 0.570 ± 0.019 vs 0.079 ± 0.010; 0.353 ± 0.016, 0.654 ± 0.018 and 0.854 ± 0.014 vs 0.126 ± 0.016; 11.9% ± 0.6%, 20.0% ± 1.8% and 35.8% ± 1.8% vs 3.9% ± 1.4%, all P < 0.01). MTT showed that the proliferation rates of SW480 cells were lower than that of the control group and a time-dosage dependence existed (all P < 0.05).

Adenosine can reverse the abnormal methylation of hMLH1 CpG island and promote the expression of hMLH1 so as to restrain the proliferation and promote the apoptosis of colocectal cancer cells.