Abstract: OBJECTIVE: To study the effects of selective cyclooxygenase-2 inhibitor NS-398 combined with octreotide on growth and apoptosis of human colon carcinoma cell. METHODS: Lovo cells were treated with NS-398, octreotide or both. The inhibitory effect on the proliferation of Lovo cells was measured by MTT assay. Morphologic changes were examined by electron microscopy, apoptotic percentage and cell cycle of Lovo cells were measured by flow cytometry. The expression of COX-2 mRNA was detected by RT-PCR. RESULTS: NS-398 and octreotide markedly inhibited cells growth in a time-dependent manner, combined treatment could significantly enhance the inhibitory effect than either alone (P<0.05). Apoptotic cells were studied with electron microscope. The apoptotic ratio induced by combined treatment was hihger than other groups. Furthermore, cell cycle analysis showed that S phase cells were decreased and quiescent G0/G1 phase cells accumulated (P<0.05). Compared with control group, the levels of COX-2 mRNA was down-regulated in three experimental groups (P<0.05). CONCLUSION: NS-398 combined with octreotide could synergistically inhibit growth and induce apoptosis of colon carcinoma cell, which may be attributed to cell cycle block and decrease in COX-2 mRNA expression.

Key words: colon carcinoma, cyclooxygenase inhibitor, octreotide