Department of Medicine and Aging, School of Medicine and Aging Research Center, Ce.S.I. G. d'Annunzio University Foundation, Chieti-Pescara, Italy.
J Biol Regul Homeost Agents. 2010 Apr-Jun;24(2):197-205.
Multidrug resistance (MDR) in cancer cells is often caused by the high expression of the plasma membrane drug transporter P-glycoprotein (Pgp) associated with an elevated intracellular glutathione (GSH) content in various human tumors. Several chemosensitizers reverse MDR but have significant toxicities. Sedatives are often used to control anxiety and depression in cancer patients. In this in vitro study we investigated the effects of three plant derived sedatives such as apigenin (Api), fisetin (Fis), flavonoids and honokiol (Hnk) on Pgp activity and cellular GSH content in order to evaluate their potential use as chemosensitizing agents in anticancer chemotherapy. Human doxorubicin (doxo) resistant uterine sarcoma cells (MES-SA/Dx5) that overexpress Pgp, were treated with each sedative alone (10 microM) or in combination with different doxo concentrations (2-8 microM). We measured the intracellular accumulation and cytotoxicity of doxo (MTT assay), the cellular GSH content (GSH assay) and ROS production (DFC-DA assay), in comparison with verapamil (Ver), a specific inhibitor for Pgp, used as reference molecule. We found that exposure at 2 and 8 microM doxo concentrations in the presence of Api, Fis and Hnk enhanced significantly doxo accumulation by 29+/-3.3, 20+/-4.8, 24+/-6.6 percent and 14+/-1.7, 8.3+/-4.2, 10.7+/-3.1 percent, respectively, when compared with doxo alone. These results were consistent with the increase of sensitivity towards doxo in MES-SA/Dx5, resulting in 1.7, 1.2, 1.4-fold and 1.2, 1.0 and 1.1-fold increases, respectively. Moreover, treatment with Api decreased markedly cellular GSH content (18 percent) and increased ROS production (greater than 20 percent) on MES-SA/Dx5 cells, while a significant reduction in ROS levels was observed in Hnk and Fis treated cells, when compared to untreated control. Our in vitro findings provide a rationale for innovative clinical trials to assess the use of natural sedatives or their derivatives as potential adjuvants to anticancer treatment for overcoming multidrug resistance Pgp-mediated in cancer patients.
多药耐药性（MDR）在癌细胞中通常是由高表达的质膜药物转运蛋白 P-糖蛋白（Pgp）引起的，与各种人类肿瘤中升高的细胞内谷胱甘肽（GSH）含量有关。几种化学增敏剂可逆转 MDR，但具有显著的毒性。镇静剂常用于控制癌症患者的焦虑和抑郁。在这项体外研究中，我们研究了三种植物来源的镇静剂，如芹菜素（Api）、非瑟酮（Fis）、类黄酮和厚朴酚（Hnk）对 Pgp 活性和细胞内 GSH 含量的影响，以评估它们作为癌症化疗中化学增敏剂的潜在用途。我们用单独的每种镇静剂（10μM）或与不同的阿霉素（doxo）浓度（2-8μM）组合处理过表达 Pgp 的人多柔比星（doxo）耐药子宫肉瘤细胞（MES-SA/Dx5），测量细胞内阿霉素（MTT 测定）的积累和细胞毒性、细胞内 GSH 含量（GSH 测定）和 ROS 产生（DFC-DA 测定），并与 Pgp 的特异性抑制剂维拉帕米（Ver）进行比较，维拉帕米作为参考分子。我们发现，在 2 和 8μM 的阿霉素浓度下，与单独的阿霉素相比，Api、Fis 和 Hnk 分别使阿霉素的积累显著增加 29+/-3.3、20+/-4.8、24+/-6.6%和 14+/-1.7、8.3+/-4.2、10.7+/-3.1%，这与 MES-SA/Dx5 对阿霉素的敏感性增加一致，导致 1.7、1.2、1.4 倍和 1.2、1.0 和 1.1 倍的增加。此外，与未处理的对照组相比，在 MES-SA/Dx5 细胞中，Api 处理显著降低了细胞内 GSH 含量（18%）并增加了 ROS 产生（大于 20%），而在 Hnk 和 Fis 处理的细胞中，ROS 水平显著降低。我们的体外发现为评估天然镇静剂或其衍生物作为克服癌症患者多药耐药性 Pgp 介导的癌症治疗的潜在辅助剂的临床研究提供了依据。
