RESUMO
<p><b>OBJECTIVE</b>To investigate the effect of arsenic trioxide (As2O3) on expression of anti-oncogene RAS association domain family gene 1A(RASSF1A) in nasopharyngeal carcinoma cell line CNE-2Z.</p><p><b>METHODS</b>CNE-2Z cells were treated with various concentrations of As2O3 for different times. The IC(50) values were detected by trypan blue stain assay. Cell cycle redistribution was analyzed by flow cytometry. The final concentration 2 micromol/L, 1 micromol/L, 0.5 micromol/L of As2O3 was added to CNE-2Z cell for succedent experiments. The controls and no drugs of CNE-2Z cells were cultivated for 48 h. Methylation specific PCR was used to detect the change of methylation status of RASSF1A gene. The expression of RASSF1A gene was detected by reverse transcription PCR and Western blot at mRNA and protein level.</p><p><b>RESULTS</b>The suppression of cell proliferation by As2O3 was time and dose-dependent. After being treated with As2O3, the IC(50) values of As2O3 were (1.50 +/- 0.05), (1.09 +/- 0.13), (0.65 +/- 0.04) micromol/L at 24, 48, and 72 h, respectively. As2O3 also arrested CNE-2Z cells in G2/M phase of cell cycle. After the effect of As2O3, the methylation of RASSF1A gene became weaker by increasing the concentration of As2O3; and the expression of RASSF1A gene became stronger at mRNA and protein level. Between different concentration of As2O3 group and no drugs group, the differences had statistical significance (P < 0.05). Along with increasing the concentration of As2O3, the expression of RASSF1A gene became stronger at mRNA and protein level, the methylation of RASSF1A gene became weaker and weaker.</p><p><b>CONCLUSIONS</b>As2O3 can activate the expression of RASSF1A gene to inhibit the cell cycle progress of nasopharyngeal carcinoma cell line.</p>