外源精氨酸对不同诱导型一氧化氮合酶表达程度的胃癌细胞生长的影响

目的探讨诱导型一氧化氮合酶（iNOs）表达与外源精氨酸补充对胃癌细胞生长的影响。方法RT-PCR法检测胃癌细胞株SGC-7901及MGC-803中精氨酸酶Ⅰ、Ⅱ（AⅠ、AⅡ）及iNOS的mRNA表达，MTT法检测分别培养于富／无精氨酸培养基的SGC-7901及MGC-803胃癌细胞株的生长情况，及加入1μmol／LNOS抑制剂L-单甲基精氨酸（LMMA）后的生长变化。结果iNOS在胃癌细胞株MGC-803强表达，但在胃癌细胞株SGC-7901表达极弱；2种细胞株AⅡ均强表达而AⅠ无表达。无论是否存在LMMA，富精氨酸培养条件下胃癌细胞株sGC-7901的增殖均强于无精氨酸时（P〈0．05），而在富／无精氨酸培养基中，是否加入LMMA均不影响胃癌细胞株SGC-790l的增殖（P〉0．05）。无LMMA时，胃癌细胞株MGC-803在富精氨酸培养条件下的增殖强于无精氨酸时（P〈0．05）；在无精氨酸培养基中加入LMMA不影响细胞生长（P〉0．05）；但在富精氨酸培养基加入LMMA可显著促进胃癌细胞株MGC-803生长（P〈0．05）。结论外源精氨酸补充对iNOS高表达的胃癌细胞可能因iNOS产物的增加而产生细胞抑制作用，精氨酸耗竭策略可能更适合低表达iNOS的肿瘤细胞。

The Effect of Exogenous Arginine on Proliferation of Gastric Cancer Cells with Different Expressions of Inducible Nitric Oxide Synthase

Objective To investigate the effect of exogenous arginine expressions and the supplement of exogenous arginine on proliferation of gastric cancer cells with different expressions of nitric oxide synthase. Methods The mRNA expression of arginase Ⅰ （A Ⅰ ）, arginase Ⅱ （A Ⅱ ）, and inducible nitric oxide synthase （iNOS） in 2 gastric cancer cell lines, SGC-7901 and MGC-803, were detected by RT-PCR. MTT assay was used for the study on proliferation of cells in medium with/without arginine before and after lmM of L-monomethylarginine （LMMA）, an inhibitor of iNOS, was added. Results Strong expression of AⅡ was found in both cell lines while the expression of AI could not be detected. The iNOS expression was found strong in MGC-803 ceils but weak in SGC-7901 cells. For SGC-7901 cells, the cells growth rates showed no significant difference in both arginine and arginine-free medium before or after LMMA addition （P〉0.05）, while in medium with arginine the cells growth always turned out better than that in arginine-free medium whether or not LMMA was added （P〈0.05）. This kind of arginine-depended growth was also found in MGC-803 cells before the addition of LMMA （P〈0. 05）. The cells growth of MGC-803 with arginine-free medium showed no significant difference before and after the addition of LMMA （P〉0.05）, while LMMA addition significantly improved the proliferation of MGC-803 cells in medium with arginine （P〈0.05）. Conclusion Exogenous arginine may inhibit the growth of gastric cancer cells with high iNOS expression, which implies that the arginine depletion strategy for cancer therapy may be more suitable for the cancer cells with low iNOS expression.