大黄素对K562/ADM细胞阿霉素耐药的抑制作用

探讨大黄素抑制人慢性粒细胞白血病细胞耐阿霉素变异株K562/ADM的药效学及作用机制。以维拉帕米为阳性药，阿霉素为工具药，采用MTT法测定大黄素与阿霉素合用对细胞增殖的抑制作用；使用流式细胞仪考察了大黄素对于阿霉素诱导K562/ADM细胞周期阻滞和凋亡的促进作用；并采用Western blot法检测了大黄素对P-gp、Bcr-Abl和STAT5蛋白表达的影响；进一步通过P-gp单克隆藻红蛋白键合UIC2抗体结合实验探讨了大黄素是否是P-gp的底物。实验结果显示，大黄素与阿霉素合用可显著抑制K562/ADM的增殖，并呈量效关系；可促进阿霉素诱导的K562/ADM细胞G₂/M期周期阻滞和细胞凋亡；不同剂量的大黄素可有效抑制P-gp、Bcr-Abl、STAT5蛋白表达及磷酸化；UIC2抗体结合实验结果则表明大黄素可能不是P-gp的底物。因此，大黄素能够在体外有效抑制K562/ADM阿霉素耐药，其机制可能不是通过底物竞争性抑制作用，而是与大黄素直接降低P-gp、Bcr-Abl及STAT5蛋白表达和磷酸化有关。

Inhibiting effect of emodin on adriamycin-resistance of K562/ADM cell line

The aim of the study was to evaluate and explore the inhibition effect of emodin on the adriamycin-resistance in K562/ADM cell line. In this study, verapamil and adriamycin were used as positive drug and tool drug, respectively. Cell viability was measured by MTT. The effect of emodin combined with adriamycin on cell cycle and apoptosis was determined by flowcytometry. The protein expression of P-gp, Bcr-Abl and STAT5 was analyzed by Western blot. Emodin inducing conformational change of P-gp with UIC2 antibody was detected by FCM. The results showed that emodin dramatically enhanced the cytotoxic effect of adriamycin in a concentration-dependent manner. Emodin promoted cell cycle arrest in G₂/M phase and adriamycin-induced apoptosis. It down-regulated the protein expression levels of P-gp, Bcr-Abl and STAT5. The results of the UIC2 binding experiment showed that emodin may not be the substrate of P-gp. It could effectively inhibit adriamycin-resistance in vivo. The mechanism of emodin inhibiting drug-resistance of K562/ADM may be related to the decrease of P-gp, Bcr-Abl and STAT5 protein expression, instead of competitive inhibition of P-gp.