胸苷酸合成酶、二氢嘧啶脱氢酶和胸苷磷酸化酶mRNA在胃癌中的表达及其意义

The mRNA expression and significance of thymidylate synthase,dihydropyrimidine dehydrogenase and thymidine phosphorylase in gastric carcinoma

目的探讨胸苷酸合成酶(TS)、二氢嘧啶脱氢酶(DPD)和胸苷磷酸化酶(TP)在胃癌中的mRNA表达,及与临床病理特征和5-氟尿嘧啶(5-Fu)化疗敏感性的关系。方法应用半定量逆转录-聚合酶链反应(RT-RCR)检测了TS、DPD和TP mRNA在4株胃癌细胞、52例胃癌肿瘤和正常组织中的表达,比较了酶表达水平和临床病理特征之间的关系;噻唑蓝(MTT)法检测4株胃癌细胞的5-Fu半数抑制浓度(IC50),及30例标本的5-Fu体外药物敏感性,探讨其与氟尿嘧啶代谢酶mRNA水平的关系。结果4株胃癌细胞均阳性表达TS、DPD和TP mRNA,DPD mRNA水平与5-Fu IC50之间显著相关(r=0.999,P<0.01),TS mRNA或TP mRNA与5-Fu IC50之间无显著相关性(P>0.05)。肿瘤组织的TS和TP mRNA水平均显著高于邻近正常组织(1.32±0.70 vs 0.93±0.48,P<0.01;0.65±0.37 vs 0.51±0.33,P<0.01),DPD mRNA水平在肿瘤与正常组织间的差异无统计学意义(0.89±0.39 vs 0.93±0.47,P>0.05)。TS表达与浸润深度(P<0.05)、远处转移(P<0.01)和TNM分期(P<0.01)相关,DPD在肠型胃癌中的表达显著高于弥漫型(P<0.01),且倾向高表达于肿瘤面积<5cm者(P<0.01),TP mRNA表达与浸润深度(P<0.05)和远处转移(P<0.05)有关。TS mRNA(r=-0.540,P<0.01)及DPD mRNA水平(r=-0.672,P<0.01)与5-Fu敏感性负相关,TP水平与5-Fu敏感性无显著相关(r=-0.317,P>0.05)。结论胃癌肿瘤内TS和TP mRNA表达显著高于正常组织,且与胃癌分期关系密切,DPD mRNA与Laurén分型和肿瘤面积有关,细胞试验和原代培养均提示DPD mRNA低水平表达可能是5-Fu高敏感性的预测指标。

Objective To evaluate the mRNA expression levels of thymidylate synthase （TS）, dihydropyr/midine dehydrogenase （DPD） and thymidine phosphorylase （TP） in gastric carcinoma,and to assess whether the expression levels of these enzymes have any relationship with clinicopathological features or 5-fluorouracil （5-Fu） chemosensitivity. Methods The TS/DPD/TP mRNA expression in 4 gastric carcinoma cell lines ,tumor tissue and adjacent normal tissue of 52 patients with gastric carcinoma was detected by semi-quantitative reverse-transcription polymerase chain reaction （RT-PCR）. MTr assay was used to evaluate 50% inhibitory concentration of growth （IC50） of 5-Fu of 4 gastric cancer cell lines, and inhibitory rate of primary culture cells of 30 cases of gastric cancer. Results In 4 gastric cancer cell lines, DPD mRNA level was correlated with 5-Fu IC50 （ r = 0.999, P 〈 0.01 ）, but TS or TP mRNA levels were not correlated with 5-Fu IC50 （ P 〉 0.05 ）. TS and TP mRNA levels in tumor tissues were both significandy higher than those in normal tissues （ 1.32 ± 0.70 vs 0.93 ± 0.48, P 〈 0.01 ; 0.65 ± 0.37 vs 0.51 ± 0.33 ,P 〈0.01 ） ,but there was no significant difference in DPD mRNA expression between tumor and norreal tissue （0.89 ± 0.39 vs 0.93 ±0.47, P 〉 0.05 ）. The expression of TS mRNA was closely correlated with the depth of invasion （ P 〈 0.05 ）, distant metastasis （ P 〈 0.01 ） and TNM stage （ P 〈 0.01 ）, DPD mRNA tended to be highly expressed in intestinal-type gastric cancer （ P 〈 0.01 ） or the cases of tumor surface 〈 5 cm （P 〈 0.01 ）, and TP mRNA levels correlated significantly with depth of invasion （P 〈 0.05 ） and distant metastasis （ P 〈 0.05 ）. TS （ r = - 0. 540,P 〈 0.01 ） and DPD mRNA （ r = - 0. 672,P 〈 0.01 ） were inversely associated with 5-Fu sensitivity, respectively, but no significant association was observed between TP mRNA expression and 5-Fu sensitivity （ r = - 0.317, P 〉 0.05 ）. Conclusion TS and TP mRNA levels of tttmor tissues were both significantly higher than those of normal tissues in gastric cancer, and correlated very well with clinical stage. DPD mRNA expression was correlated significantly with Laurrn pathologic classification and tumor surface, and DPD mRNA level might be a predictive index of 5- Fu chemosensitivity.