Cancer Center, Sun Yat-Sen University, Guangzhou 510060, People's Republic of China.
Anticancer Res. 2009 Nov;29(11):4597-604.
Our previous studies have shown that tetrandrine (Tet) reverses the effect of P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) both in vitro and in vivo. 5-Bromotetrandrine (Br-Tet) is a newly synthesized brominated derivative of Tet. In this study, we investigated the MDR reversal activity of Br-Tet in vitro and in vivo and the mechanism involved in this reversal.
The ability of Br-Tet to reverse drug resistance in vitro was evaluated by MTT assay in human MDR KBv200 cells and the parental drug-sensitive KB cells. A KBv200 cell xenograft model was established to investigate the MDR reversal activity of Br-Tet in vivo. Doxorubicin (Dox) accumulation in KBv200 and KB cell lines was determined by flow cytometry and Dox accumulation in KBv200 xenografts tissue was examined by spectrofluorometer. The effect of Br-Tet on the expression of P-glycoprotein was detected by flow cytometry and Western blot, respectively.
Br-Tet significantly enhanced the cytotoxicity of Dox, paclitaxel, taxotere, vincristine and epirubicin in KBv200 cells but not in KB cells. Co-administration of 10 mg/kg Br-Tet and 2 mg/kg epirubicin significantly enhanced the antitumor activity of epirubicin without increasing the toxicity. Br-Tet increased the Dox accumulation in the MDR KBv200 cell line and in KBv200 xenograft tissue in a time- and dose-dependent manner. However, it did not reduce the expression of P-gp in KBv200 cells.
Br-Tet caused a significant reversal of P-gp-mediated MDR, not only in vitro but also in vivo. The MDR reversal activity of Br-Tet in vivo was associated with the enhancement of accumulation of chemotherapeutical drugs in tumor tissue.
我们之前的研究表明，汉防己甲素（Tet）在体内外均可逆转 P 糖蛋白（P-gp）介导的多药耐药（MDR）。5-溴汉防己甲素（Br-Tet）是 Tet 的一种新合成的溴代衍生物。本研究旨在探讨 Br-Tet 体内外逆转 MDR 的作用及其机制。
采用 MTT 法检测 Br-Tet 在人多药耐药 KBv200 细胞及其亲本敏感 KB 细胞中的逆转耐药作用。建立 KBv200 细胞异种移植模型，研究 Br-Tet 体内逆转耐药作用。采用流式细胞术和荧光分光光度计分别检测 Br-Tet 对 KBv200 细胞系和 KBv200 异种移植组织中阿霉素（Dox）积累的影响。采用流式细胞术和 Western blot 分别检测 Br-Tet 对 P-糖蛋白表达的影响。
Br-Tet 显著增强了 Dox、紫杉醇、多西他赛、长春新碱和表柔比星在 KBv200 细胞中的细胞毒性，但对 KB 细胞无此作用。给予 10 mg/kg Br-Tet 和 2 mg/kg 表柔比星联合治疗可显著增强表柔比星的抗肿瘤活性，而不增加毒性。Br-Tet 呈时间和剂量依赖性增加 MDR KBv200 细胞系和 KBv200 异种移植组织中 Dox 的积累，但不降低 KBv200 细胞中 P-gp 的表达。
Br-Tet 不仅在体外，而且在体内显著逆转了 P-gp 介导的 MDR。Br-Tet 在体内的逆转耐药作用与增强化疗药物在肿瘤组织中的积累有关。
