[Effects of arsenic trioxide on human coronary smooth muscle cells: experiment in vitro].

OBJECTIVE: To study the apoptotic effects of arsenic trioxide on human coronary smooth muscle cells (HCSMCs). METHODS: HCSMCs were cultured and randomly divided into 5 groups to be treated by arsenic trioxide of the concentrations 1.0, 2.0, 3.0, 4.0, and 5.0 micromol/L for 48 h. Cell growth curve was drawn by MTT method. DNA electrophoresis was used to observe the apoptosis. Western blotting was conducted to examine the protein expression of Bax, an apoptosis-promoting gene, and Bcl-2, an apoptosis-inhibiting gene. Other HCSMCs were cultured with 4.0 micromol/L arsenic trioxide for 48 h, then transmission electron microscopy was used to observe the ultra-structure and TUNEL was used to detect the percentage of apoptotic cells. HCSMCs not treated with arsenic trioxide were used as control group. RESULTS: Arsenic trioxide of different concentrations inhibited the proliferation of HCSMCs dose and time-dependently. When the concentration of arsenic trioxide was 5.0 micromol/L the number of living cells was (4.41 +/- 0.10) x 10(5)/ml, significantly lower than that of the control group [(30.11 +/- 0.93) x 10(5)/ml, P < 0.05]. Apoptosis bodies were observed under the transmission electron microscope. DNA electrophoresis showed hazy ladders, especially when the concentrations were 3.0 - 4.0 micromol/L. When the concentration was 5.0 micromol/L the number of necrotic cells increased remarkably and apoptosis became less significant. TUNEL showed that the apoptotic cells increased from 16.0% +/- 3.1% to 38.7% +/- 2.7% (P < 0.05). MTT test showed that arsenic trioxide decreased the absorbance of HCSMCs dose and time-dependently. Western blotting showed that the Bcl-2 expression was decreased and the expression of Bax increased after treatment of arsenic trioxide. CONCLUSION: Arsenic trioxide exerts an apoptotic effect on HCSMCs.