Effects Of Sodium Butyrate On The Proliferation And Differentiation Of Human Gastric Cancer Cell Line AGS

BACKGROUND & OBJECTIVE: Sodium butyrate (NaBT) is a kind of short chain fatty acids (SCFA), which is produced in the large bowel of human by anaerobic bacterial fermentation of dietary fiber. Many researches indicated that NaBT could inhibit the proliferation and induce the differentiation of various tumorous cells, including hepatoma, ovarian cancer and colon carcinoma. This study was to investigate effects of NaBT on the proliferation and differentiation of human gastric carcinoma cell line AGS and the possible mechanism.METHODS: AGS cells on the logarithmic phase of growth were treated with different concentrations NaBT (0, 1.0, 2.0, 4.0 mmol/L) and cultured for 24, 48, and 72 h respectively. Then, cells were collected for future use. Cell proliferation was detected by MTT assay; cell morphology changes were observed under optical and transmission electron microscopy; the distribution of cell-cycle was detected by flow cytometry (FCM). The expression of cyclin-dependent kinase inhibitor P21 was detected by reverse transcription-polymerse chain reaction (RT-PCR) and Western blot.RESULTS: 1. Compared with the control group, the proliferation rates of AGS cells treated by different concentrations (0, 1.0, 2.0, 4.0 mmol/L) of sodium butyrate were inhibited significantly. The inhibitory effect of sodium butyrate on cell proliferation was in a time- and dose-dependent manner. When cells were treated with 4.0 mmol/L sodium butyrate for 72 h, the inhibitory rate was as high as 81.54% (P<0.01). 2. After treated by sodium butyrate, in comparison with the control, cells revealed obvious changes, including decreased microvilli, regular nuclei with smaller N/C ratios, fewer and regular nucleoli, and increased mitochondria. 3. After incubation with 1.0, 2.0, and 4.0 mmol/L sodium butyrate for 24 h, the percentage of S-phase cells decreased from 57.1% to 44.3%, 29.0%, and 21.6% respectively (P< 0.01), while the cells at G0/G1-phase increased to 33.5% (P > 0.05), 45.8%, and 54.5% (P< 0.01), respectively. And at the same time, DNA ploidy of AGS cells changed: the DNA ploidy of control group was tetraploid or near-tetraploid, after incubation with sodium butyrate for 24 h, diploid or near-diploid DNA appeared in AGS cells. 4. After AGS cells treated by differentent concentrations NaBT for 24h, the expression of cyclin-dependent kinase inhibitor P21 was up-regulated both in mRNA and protein level, which were statistically significant comparing with the control group (P<0.05). And as the treatment concentration of NaBT increased, this effects trended to be strengthened.CONCLUSIONS: NaBT could arrest the human gastric carcinoma cell Line AGS at G1 period by up-regulating the expression of cyclin-dependent kinase inhibitor P21, then inhibit cell proliferation and induce cell differentiation. This could reverse its malignant phenotype to some extent.