人胃癌细胞环氧合酶-2调节延迟整流钾通道的实验研究

目的：研究胃癌细胞中延迟整流钾电流（Ik)与环氧合酶－2（COX－2）表达的关系。探讨COX－2在胃癌发生中的机制。方法：构建人COX－2的反义真核表达载体,转染COX－2高表达的人胃癌细胞系SGC7901。采用穿孔膜片钳全细胞记录法比较反义核酸转染和COX－2抑制剂消炎痛对细胞的Ik的细胞,以MTT法检测延迟整流钾通道抑制剂对GSC7901及其反义核酸转染细胞生长的抑制作用。结果：反义核酸稳定转染的细胞COX－2在蛋白及mRNA水平表达均下调,膜片钳记录提示,在钳制电压为－40mV,阶跃电压为－80mV- 80mV时,在每个测试电压下,转染细胞的Ik均显著低于亲本细胞,给骒消炎痛（10umol/L)后,Ik亦显著降低,停药冲洗后可完全恢复,延迟整流钾通道的抑制剂四乙铵（TEA）及四氨吡啶（4－AP）对SGC7901及转染细胞的生长有显著抑制作用。并具有剂量依赖性。结论：人胃癌细胞系SGC7901存在Ik,延迟整流钾通道与细胞生长有关,胃癌细胞中高表达的COX－2可能通过调节该通道影响细胞的生物学行为。

Delayed rectifier K(+) channel regulated by cyclooxygenase-2 in human gastric cancer cell

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.