[Effects of sodium butyrate on growth, apoptosis and telomerase activity in Hep-2 cells].

OBJECTIVE: To study the effects of sodium butyrate (SB) on growth, apoptosis and telomerase activity in Hep-2 cells. METHODS: Growth inhibition effect of SB on Hep-2 cells was assessed by methyl thiazolyl tetrazolium (MTT) assay. Morphological alterations were observed by electronic microscope. Cell apoptosis was confirmed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL) method, DNA fragmentation and flow cytometry (FCM). Cell cycle was analyzed by FCM. Telomerase activity was examined by telomeric repeat amplification protocol (TRAP)-silver staining. The expression status of telomerase subunits was analyzed by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: A time-and dose-dependent inhibition was detected in cells treated with SB. Typical morphological changes of apoptotic cells were observed under electronic microscopy. The characteristic DNA fragmentation of apoptotic cells was detected by agarose gel electrophoresis. Apoptosis and the changes of cell cycle were confirmed by TUNEL method and FCM. The apoptosis indexes of the cells before treatment and at 72 h after SB (2.5 mmol/L) treatment were 2.27 +/- 1.18 and 33.50 +/- 2.75 respectively, the apoptosis rates were 2. 86% and 31. 28% respectively, the proportion of the cells at G0/G1 stage were 50.38% and 70.88% respectively, the proportion of the cells at S stage were 27.40% and 8.20% respectively, and the proliferation indexes of the cells were 49.62% and 29.12% respectively. Telomerase activity and expression level of human telomerase reverse transcriptase (hTERT), the key subunit of telomerase, decreased after SB treatment. No significant changes were observed in the expression of human telomerase RNA (hTR) and human telomerase associated protein (hTP1), the other two subunit of telomerase. CONCLUSION: SB could inhibit growth of Hep-2 cells and induce apoptosis in the cells, and inhibit telomerase activity by decrease expression level of hTERT.