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目的 探讨白介素 4 (IL 4 )基因修饰对儿童实体瘤多药耐药 (MDR)的逆转作用及可能机制。方法 用逆转录病毒载体将人IL 4基因导入人肝母细胞瘤细胞系HepG2 ,采用MTT生物活性法检测瘤细胞对化疗药物的敏感性。间接免疫荧光分光光度分析瘤细胞P 糖蛋白 (P gp)的表达率。微量荧光分光光度法分析瘤细胞内阿霉素 (ADM)聚集量。结果 IL 4基因修饰显著降低瘤细胞对种化疗药物的半数抑制浓度 (IC5 0 ) ,表现出MDR逆转效应 (耐药逆转倍数在 6～ 32倍数间 )及明显增加化疗药物在瘤细胞内聚集 ,同时IL 4基因修饰瘤细胞P gp阳性表达率 (5± 0 6 % )较野生型及空载体修饰细胞 (98 5± 0 5 %、97 0± 1 0 % )明显减低。IL 4基因修饰对瘤细胞的MDR逆转作用可为PKC激活剂TPA所阻断。IL 4基因修饰瘤苗及其培养上清与野生型细胞共培养 ,也可使野生型瘤细胞产生MDR逆转效应。结论 IL 4基因修饰瘤苗可通过自分泌、旁分泌形式逆转瘤细胞MDR ,此作用可能与其抑制PKC活性及下调P gp表达
Objective To investigate the reversal effect and possible mechanism of interleukin 4 (IL 4) gene modification on multidrug resistance (MDR) in childhood solid tumors. Methods Human IL 4 gene was introduced into human hepatoblastoma cell line HepG2 by retroviral vector and MTT assay was used to detect the sensitivity of tumor cells to chemotherapeutic drugs. Indirect immunofluorescence spectrophotometric analysis of tumor cells P glycoprotein (P gp) expression rate. Micro fluorescence spectrometry analysis of tumor cells adriamycin (ADM) accumulation. Results IL 4 gene modification significantly reduced the median inhibitory concentration (IC 50) of tumor cells to chemotherapeutic drugs, showed MDR reversal effect (6 to 32 fold multiple reversal of drug resistance), and significantly increased the accumulation of chemotherapeutic drugs in tumor cells. At the same time, the positive expression rate of P gp in IL 4 gene-modified tumor cells was significantly lower than that in wild-type and empty vector-modified cells (98 ± 5%, 97 ± 10%). The MDR reversal effect of IL 4 gene modification on tumor cells can be blocked by TPA, a PKC activator. IL 4 gene-modified tumor vaccine and its culture supernatant co-cultured with wild-type cells, but also make wild-type tumor cells produce MDR reversal effect. Conclusion The IL 4 gene modified vaccine can reverse the MDR of tumor cells through autocrine and paracrine forms, which may be related to its inhibition of PKC activity and down-regulation of P gp expression