RESUMO
<p><b>OBJECTIVE</b>To study the effects of NS398, a selective cyclooxygenase-2 (COX-2) inhibitor, on the transcription and translation of BCL-3 and its regulatory gene cyclin D1 in colon cancer cell line SW480.</p><p><b>METHODS</b>Human colon cancer cells SW480 were divided into two groups: SW480 cells in experimental group were treated with NS398 in different concentrations(25 micromol/L, 50 micromol/L, 100 micromol/L and 200 micromol/L) for 48 h or 72 h. SW480 cells in control group were treated with media which did not contain NS398. Then the expressions of BCL-3 and cyclin D1 were detected by RT-PCR, Western blot, and immunocytochemistry.</p><p><b>RESULTS</b>At 48 hours RT-PCR showed that BCL-3 mRNA and cyclin D1 mRNA decreased in a dose-dependent manner in the experimental group. However, there were no significant differences in the levels of BCL-3 protein and cyclin D1 protein between two groups (P>0.05). At 72 hours, BCL-3 protein and cyclin D1 protein also decreased in a dose-dependent manner in the experimental group. When the concentration of NS398 reached 100 micromol/L, the differences between the two groups in the expression of BCL-3 mRNA and protein became statistically significant (P<0.01). When the concentration of NS398 reached 50 micromol/L, the differences in the expression of cyclin D1 mRNA and protein were statistically significant (P<0.05).</p><p><b>CONCLUSIONS</b>BCL-3 is expressed in colon cancer cell line SW480. COX-2 inhibitor can inhibit the expression of BCL-3 and cyclin D1 in a dose-dependent manner. NS398 may down-regulate the expression of cyclin D1 through BCL-3.</p>