Objective      To explore the effect of 5-iodotubercidin (ITU) on the proliferation and apopto

sis in human colon cancer HT-29 cells and on the expression of deleted in liver cancer-1 (DLC-1) gene.       Methods      HT-29 cells were treated with different concentrations of ITU (0.1

0.5

1

2

4

6

8

and 10 μmol/L) for 48 h

and the cell viability was studied by MTT assay. HT-29 cells were co-cultured with different concentrations of ITU (0

2

4

and 6 μmol/L) for 48 h

and the apoptosis rate was detected by flow cytometry. Meanwhile

the methylation levels of CpG islands at promoter region of DLC-1 gene were determined by bisulfite sequencing PCR (BSP). The DLC-1 mRNA expression levels were detected by reverse transcription-polymerase chain reaction (RT-PCR) and the DLC-1 protein expression levels were detected by Western blotting.       Results      ITU distinctly inhibited the proliferation of HT-29 cells in a concentration-dependent manner in a certain range

and the 6 μmol/L group had the greatest effect

with IC

50

of 5.92±0.62 μmol/L. The apoptotic rates of HT-29 cells treated with ITU (0

2

4

and 6 μmol/L) were (9.56±2.21)%

(22.18±3.16)%

(34.23±3.16)%

and (40.5±3.16)%

respectively

which were increased in a concentration-dependent manner. The methylation rates of CpG islands at the promoter region of DLC-1 gene were 91.67%

75.00%

61.67%

and 43.33%

respectively

after treatment with ITU (0

2

4

and 6 μmol/L). The results showed that ITU could decrease the methylation of DLC-1 gene promoter region. Little of DLC-1 mRNA and protein expression was detected in HT-29 cells

and ITU treatment increased the expression in a concentration-dependent manner.       Conclusion      ITU can inhibit the proliferation of HT-29 cells and induce apoptosis through decreasing the methylation level of DLC-1 gene promoter region and increasing the DLC-1 gene expression.