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目的 探讨巨噬细胞在结直肠癌化疗中的调控作用。方法 应用ELISA法分别检测结直肠癌细胞系LS174T、Clone A、Colo320、MIP101的胸苷磷酸化酶(dThdPase)蛋白含量。采用MTT分析,分别测定出氟尿嘧啶(5-FU)和5’-脱氧氟尿苷(5’-DFUR)对上述4种癌细胞的半数有效浓度(IC50)。然后把5’-DFUR加入培养基中同人血单核细胞一起培养24 h,其培养上清液2倍稀释后加入结直肠癌细胞中行MTT分析测定其IC50有无改变。同时测定单核细胞在不同浓度5’-DFUR中的存活率。结果 4种结直肠癌细胞仅LS174T检出0.5 U/mg的dThdPase蛋白,其它3种未检出。4种癌细胞对5-DFUR的IC50均明显高于5-FU(P<0.01)。同人血单核细胞一起培养后,5’-DFUR对4种癌细胞的IC50明显下降,仅相当于处理前的11.6％～34.3％(P<0.05),同时发现5’-DFUR对人血单核细胞无明显生长抑制作用。结论 被检结直肠癌细胞因缺乏dThdPase活性,不能在细胞内转化抗癌药物5’-DFUR为5-FU发挥细胞毒作用;同人血单核细胞一起培养后,5’-DFUR在单核细胞内dThdPase的催化下,可转化成5-FU并释放到培养基中发挥抗癌作用。
Objective To investigate the regulation of macrophages in chemotherapy of colorectal cancer. Methods The protein levels of thymidine phosphorylase (dThdPase) in colorectal cancer cell lines LS174T, Clone A, Colo320 and MIP101 were detected by ELISA. MTT assay was used to determine the median effective concentration (IC50) of 5-fluorouracil (5-FU) and 5’-deoxyfluorouridine (5-DFUR) against the above four cancer cells. The 5’-DFUR was then added to the culture medium for culturing with human blood mononuclear cells for 24 h. The culture supernatants were diluted 2-fold and added to colorectal cancer cells for determination of IC50 by MTT assay. Monocytes were also assayed for survival in different concentrations of 5’-DFUR. Results Only 4 U of dThdPase protein was detected by LS174T in 4 kinds of colorectal cancer cells, while the others were not detected. The IC50 of 5 kinds of cancer cells to 5-DFUR were significantly higher than that of 5-FU (P <0.01). After cultured with human blood mononuclear cells, the IC50 of 5-DFUR decreased significantly to 4 kinds of cancer cells, which was only 11.6% -34.3% (P <0.05) before treatment. At the same time, it was found that 5’- No obvious growth inhibition of nuclear cells. CONCLUSIONS: Colorectal cancer cells lacking dThdPase activity and can not transform 5’-DFUR into 5-FU can exert cytotoxic effect in human colorectal cancer cells. After cultured with human blood mononuclear cells, Catalyzed by dThdPase, it can be converted to 5-FU and released into the culture medium to exert anti-cancer effects.