Objective: To correlate delayed rectifier K(+) channel to cyclooxygenase-2 (COX-2) in onco genesis of human gastric cancer cell.
Methods: Human COX-2 encoding gene was cloned with RT-PCR strategy and its antisense recombinant eukaryotic expression vector was constructed. COX-2 highly expressed human gastric cancer cell line SGC7901 was stably transfected with the antisense vector. The whole-cell recording technique of perforated patch clamp was employed to observe the change of delayed rectifier K(+) current (I(k)) of SGC7901 after gene transfer or treatment with COX-2 inhibitor indomethacin. MTT was also performed to determine the effect of delayed rectifier K(+) channel inhibitors on cell growth.
Results: Stably transfected cell (7901-AS) was obtained and a down-regulated expression of COX-2 protein and mRNA in the cell was achieved. Patch clamp recording showed that both SGC7901 and 7901-AS cells had a typical delayed rectifier K(+) current. However, I(k) was significantly lower (P < 0.01) in transfected cell or cell treated with indomethacin at each test potential. The altered I(k) could be entirely recovered after drug removal from the cells. K(+) channel blockers tetraethylammonium (TEA) and 4-aminopyridine (4-AP) could retard the growth of SGC7901 and the transfected cell in a dose-dependent manner.
Conclusion: Delayed rectifier K(+) channel, existing in human gastric cancer cell line SGC7901, is related to the growth of the cell. The highly expressed COX-2 may affect the biological behavior of gastric cancer cell by regulating this ion channel.