氟尿嘧啶对胃肠道肿瘤细胞DPD和TP表达的影响

Regulation of dihydropyrimidine dehydrogenase and thymidine phosphorylase expression in gastrointestinal cancer cells treated with fluorouracil

背景与目的:氟尿嘧啶(5-FU)是胃肠道肿瘤化疗的首选和基本用药,其分解代谢的限速酶———二氢嘧啶脱氢酶(DPD)和激活酶———胸苷磷酸化酶(TP)决定了肿瘤区域的药物浓度和作用,且与5-FU的化疗敏感性有一定相关性。本研究旨在观察胃肠道肿瘤细胞中,5-FU对DPD和TP的表达有无调节作用。方法:选取胃癌细胞株SGC7901、大肠癌细胞株SW 1116和人脐静脉内皮细胞ECV-304,用不同浓度的5-FU作用不同时间后,以RT-PCR,ELISA和免疫组化等方法分别检测DPD和TP的mRNA和蛋白含量,观察药物作用对不同细胞代谢酶表达的影响。结果:5-FU作用于不同细胞后表现不同:其中SGC7901、SW 1116两株肿瘤细胞的DPD蛋白水平均上调,且表现为时间依赖性;在上述两株细胞中,TP蛋白表达呈小剂量上调、大剂量下调的双重效应,并随时间延长表达增加;5-FU作用后DPD和TP mRNA水平则无显著改变。ECV-304细胞株的DPD和TP mRNA与蛋白表达不受5-FU影响。结论:胃肠道肿瘤细胞内,DPD和TP表达在蛋白水平上受5-FU调控,而正常细胞不受影响。

Background and purpose： Fluorouracil（5-FU） is considered as the first-line and principal component of chemotherapy regimen for gastrointestinal cancer, and the concentration and functionality of 5-FU in the tumor area are determined by the expression of dihydropyrimidine dehydrogenase（DPD） and thymidine phosphorylase（TP） the rate-limiting enzyme of catabolism and activating enzyme of 5-FU, respectively.It also is relevant to the ehemosensitivity of 5-FU. This study was to investigate whether the expressions of DPD and TP in gastrointestinal cancer cells are regulated by 5-FU. Methods： Gastric carcinoma cell line SGC7901, colonic carcinoma cell line SWllI6 and human umbilical vein endothelial cell line ECV-304, were exposured to 5-FU at different eoneentrations and time, mRNA and protein levels of DPD or TP were determined by reverse transcription polymerase chain reaction（ RT-PCR）, ELISA and immunohistochemistry, the impact on the expression of DPD and TP after cells exposure to 5-FU was assessed. Results： After cell exposure to 5-FU, DPD protein levels of two tumor cell lines, SGC7901 and SW1116, were upregulated in a time-dependent manner, and TP protein levels were also affected in a similar way, and mainly presented a paradox of upregulation by low-dose 5-FU, but down- regulation by high-dose drug. both DPD and TP mRNA levels after 5-FU exposure seemed to be stable. However, DPD or TP mRNA and protein expression levels of ECV-304 cell line were not affected by 5-FU. Conclusions： Both DPD and TP levels after 5-FU exposure were regulated at the protein Revel in gastrointestinal tumor cells, but not in normal cells.