[Effects of gastrin receptor antagonist and cyclooxygenase-2 inhibitor on proliferation and apoptosis of gastric cancer cell].

OBJECTIVE: To investigate the regulative roles of the gastrin receptor antagonist proglumide and the specific cyclooxygenase (COX)-2 inhibitor NS-398 on the proliferation and apoptosis of gastric cancer cells. METHODS: Human gastric cancer cells of the line MKN-45 were routinely cultured in RPMI-1640 medium supplemented with 10% heat-inactivated fetal calf serum. Subconfluent cell cultures were treated with proglumide at a final concentration of 5 mmol/L, NS-398 at a final concentration of 10.0 micromol/L, or proglumide in combination with NS-398 for 48 h. The growth and proliferation of MKN-45 cells were analyzed with MTT assay. Flow cytometric analysis was used to detect the apoptosis of the gastric cancer cells. RT-PCR and Western blotting were used to detect the expression of apoptosis-inhibited gene bcl-2 mRNA and protein. RESULTS: The apoptosis rates of the cells treated by proglumide, NS-398, and combination of two agents were 24.7% +/- 3.2%, 26.7% +/- 3.4%, and 36.1% +/- 4.6% respectively, all significantly higher than that in the control group (1.6% +/- 0.6%, all P < 0.01). The apoptosis rates of the MKN-45 cells treated with proglumide combined with NS-398 was significantly greater than those of the cells treated by the two agents alone (both P < 0.05). Treatment with proglumide and NS-398 significantly reduced the bcl-2 mRNA and protein expression in the MKN-45 cells (P < 0.05). CONCLUSION: Both proglumide and NS-398 inhibit the proliferation and induce the apoptosis of human gastric cells. This apoptosis may be mediated by down-regulation of the expression of apoptosis-inhibited gene bcl-2. Co-treatment with proglumide and NS-398 have synergistic anticancer role.

Downregulation of miR-101 in gastric cancer correlates with cyclooxygenase-2 overexpression and tumor growth.

Cyclooxygenase-2 (COX-2) plays an important role in the carcinogenesis and progression of gastric cancer. It has been demonstrated that COX-2 overexpression depends on different cellular pathways, involving both transcriptional and post-transcriptional regulation. MicroRNAs (miRNAs) are small, noncoding RNAs that function as post-transcriptional regulators. Here, we characterize miR-101 expression and its role in the regulation of COX-2 expression, which in turn, will provide us with additional insights into the potential therapeutic benefits of exogenous miR-101 for treatment of gastric cancer. Our results showed that miR-101 levels in gastric cancer tissues were significantly lower than those in the matched normal tissue (P < 0.01). Furthermore, lower levels of miR-101 were associated with increased tumor invasion and lymph node metastasis (P < 0.05). We also found an inverse correlation between miR-101 and COX-2 expression in both gastric cancer specimens and cell lines. Significant decreases in COX-2 mRNA and COX-2 levels were observed in the pre-miR-101-infected gastric cancer cells. One possible mechanism of interaction is that miR-101 inhibited COX-2 expression by directly binding to the 3'-UTR of COX-2 mRNA. Overexpression of miR-101 in gastric cancer cell lines also inhibited cell proliferation and induced apoptosis in vitro, as well as inhibiting tumor growth in vivo. These results collectively indicate that miR-101 may function as a tumor suppressor in gastric cancer, with COX-2 as a direct target.

Inhibition of COX-2 and activation of peroxisome proliferator-activated receptor gamma synergistically inhibits proliferation and induces apoptosis of human pancreatic carcinoma cells.

Although inhibition of cyclooxygenase-2 (COX-2) or activation of peroxisome proliferators-activated receptor gamma (PPAR-gamma) leads to growth inhibition in malignancies, the synergistic anti-tumor effects of combination of COX-2 inhibitor (NS-398) and PPAR-gamma agonist (rosiglitazone) on the human pancreatic cancer cells remains unknown. Here, we evaluated the effects of NS-398 and/or rosiglitazone on the cell proliferation and apoptosis in a pancreatic cancer cell line, SW1990. NS-398 and rosiglitazone decreased cell proliferation in a dose- and time-dependent manner. Proliferating cell nuclear antigen (PCNA) labeling index significantly decreased in the cells treated with either NS-398 or rosiglitazone. Both NS-398 and rosiglitazone alone induced apoptotic cell death of SW1990. The combination of NS-398 and rosiglitazone exerted synergistic effects on proliferation inhibition, and apoptosis induction in SW1990 cells, with down-regulation of Bcl-2 and up-regulation of Bax expression. Our results indicate that simultaneous targeting of COX-2 and PPAR-gamma inhibits pancreatic cancer development more effectively than targeting each molecule alone.