Department of Central Laboratory,The Affiliated People’s Hospital, Jiangsu University, Jiangsu, China.
Pharm Biol. 2012 Oct;50(10):1233-40. doi: 10.3109/13880209.2012.665931.
Multidrug-resistance is a serious obstacle encountered in leukemia treatment. Recent studies have shown microRNA-21 (miR-21) is overexpressed in several types of cancer and contributes to tumor resistance to chemotherapy. In our previous studies, we found triptolide (TPL) could enhance adriamycin-induced cytotoxicity and apoptosis in K562/A02 cells.
In the present study, we investigated the mechanism of TPL on the sensitivity of K562/A02 cells to adriamycin.
Cell viability was assessed by methyl thiazolyl tetrazolium (MTT) assay. Expression of mature miR-21 was determined by SYBER green PCR. The miR-21 mimics and inhibitors were chemically synthesized and transfected into K562 cells or K562/A02 cells. PTEN protein levels was determined by western blots. PTEN promoter activity was measured by luciferase assays.
TPL (5 nmol/L) increased the sensitivity of K562/A02 to adriamycin. When adriamycin was combined with 5 nmol/L TPL, the mean apoptotic population of K562/A02 cells was increased from 4.3 to 18.5%, respectively. K562/A02 cells showed a significant reduction in miR-21 and phosphatase and tensin homolog deleted on chromosome ten (PTEN) expressions after TPL treatment. K562/A02 cells that were transfected with the miR-21 inhibitor had a significantly higher PTEN protein level than the control. K562 cells that were pre-treated with PTEN siRNA had increased survival rate compared to the control group.
Our findings indicated that triptolide modulates the sensitivity of K562/A02 cells to adriamycin by regulating miR-21 expression. Triptolide inhibited miR-21 expression and enhanced PTEN levels in K562/A02 cells.
多药耐药性是白血病治疗中遇到的严重障碍。最近的研究表明，microRNA-21（miR-21）在几种类型的癌症中过度表达，并有助于肿瘤对化疗的耐药性。在我们之前的研究中，我们发现雷公藤内酯醇（TPL）可以增强 K562/A02 细胞中阿霉素诱导的细胞毒性和细胞凋亡。
本研究旨在探讨 TPL 对 K562/A02 细胞对阿霉素敏感性的作用机制。
采用噻唑蓝（MTT）比色法评估细胞活力。采用 SYBER 绿色 PCR 法检测成熟 miR-21 的表达。化学合成 miR-21 模拟物和抑制剂并转染至 K562 细胞或 K562/A02 细胞。采用 Western blot 法检测 PTEN 蛋白水平。采用荧光素酶报告基因检测法测定 PTEN 启动子活性。
TPL（5 nmol/L）增加了 K562/A02 对阿霉素的敏感性。当阿霉素与 5 nmol/L TPL 联合使用时，K562/A02 细胞的平均凋亡群体分别从 4.3%增加到 18.5%。TPL 处理后，K562/A02 细胞的 miR-21 和磷酸酶张力蛋白同源物缺失的第十号染色体（PTEN）表达明显降低。与对照组相比，转染 miR-21 抑制剂的 K562/A02 细胞的 PTEN 蛋白水平显著升高。与对照组相比，用 PTEN siRNA 预处理的 K562 细胞的存活率增加。
我们的研究结果表明，雷公藤内酯醇通过调节 miR-21 表达来调节 K562/A02 细胞对阿霉素的敏感性。雷公藤内酯醇抑制 miR-21 表达，增强 K562/A02 细胞中 PTEN 水平。
