Zhang Wei, Fan Ying-Fang, Cai Chao-Yun, Wang Jing-Quan, Teng Qiu-Xu, Lei Zi-Ning, Zeng Leli, Gupta Pranav, Chen Zhe-Sheng
Institute of Plastic Surgery, Weifang Medical University, Weifang, China.
Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, Queens, NY, United States.
Front Pharmacol. 2018 Oct 9;9:1097. doi: 10.3389/fphar.2018.01097. eCollection 2018.
The main characteristic of tumor cell resistance is multidrug resistance (MDR). MDR is the principle cause of the decline in clinical efficacy of chemotherapeutic drugs. There are several mechanisms that could cause MDR. Among these, one of the most important mechanisms underlying MDR is the overexpression of adenosine triphosphate (ATP)-binding cassette (ABC) super-family of transporters, which effectively pump out cytotoxic agents and targeted anticancer drugs across the cell membrane. In recent years, studies found that ABC transporters and tyrosine kinase inhibitors (TKIs) interact with each other. TKIs may behave as substrates or inhibitors depending on the expression of specific pumps, drug concentration, their affinity for the transporters and types of co-administered agents. Therefore, we performed experiments to observe whether olmutinib could reverse MDR in cancer cells overexpressing ABCB1, ABCG2, or ABCC1 transporters. The results showed that olmutinib at 3 μM significantly reversed drug resistance mediated by ABCG2, but not by ABCB1 and ABCC1, by antagonizing the drug efflux function in ABCG2-overexpressing cells. In addition, olmutinib at reversal concentration affected neither the protein expression level nor the localization of ABCG2. The results observed from the accumulation/efflux study of olmutinib showed that olmutinib reversed ABCG2-mediated MDR with an increasing intracellular drug accumulation due to inhibited drug efflux. We also had consistent results with the ATPase assay that olmutinib stimulated ATPase activity of ABCG2 up to 3.5-fold. Additionally, the molecular interaction between olmutinib and ABCG2 was identified by docking simulation. Olmutinib not only interacts directly with ABCG2 but also works as a competitive inhibitor of the transport protein. In conclusion, olmutinib could reverse ABCG2-mediated MDR. The reversal effect of olmutinib on ABCG2-mediated MDR cells is not due to ABCG2 expression or intracellular localization, but rather related to its interaction with ABCG2 protein resulting in drug efflux inhibition and ATPase stimulation.
肿瘤细胞耐药性的主要特征是多药耐药性（MDR）。MDR是化疗药物临床疗效下降的主要原因。有几种机制可导致MDR。其中，MDR最重要的机制之一是三磷酸腺苷（ATP）结合盒（ABC）转运蛋白超家族的过表达，其可有效地将细胞毒性药物和靶向抗癌药物泵出细胞膜。近年来，研究发现ABC转运蛋白与酪氨酸激酶抑制剂（TKIs）相互作用。根据特定泵的表达、药物浓度、它们对转运蛋白的亲和力以及联合使用药物的类型，TKIs可能表现为底物或抑制剂。因此，我们进行了实验，以观察奥莫替尼是否能逆转过表达ABCB1、ABCG2或ABCC1转运蛋白的癌细胞中的MDR。结果表明，3 μM的奥莫替尼通过拮抗过表达ABCG2细胞中的药物外排功能，显著逆转了由ABCG2介导的耐药性，但对ABCB1和ABCC1介导的耐药性无效。此外，逆转浓度的奥莫替尼既不影响ABCG2的蛋白表达水平，也不影响其定位。奥莫替尼蓄积/外排研究的结果表明，奥莫替尼通过抑制药物外排增加细胞内药物蓄积，从而逆转了ABCG2介导的MDR。我们在ATP酶分析中也得到了一致的结果，即奥莫替尼可将ABCG2的ATP酶活性刺激高达3.5倍。此外，通过对接模拟确定了奥莫替尼与ABCG2之间的分子相互作用。奥莫替尼不仅直接与ABCG2相互作用，还作为转运蛋白的竞争性抑制剂发挥作用。总之，奥莫替尼可逆转ABCG2介导的MDR。奥莫替尼对ABCG2介导的MDR细胞的逆转作用不是由于ABCG2的表达或细胞内定位，而是与其与ABCG2蛋白的相互作用有关，从而导致药物外排抑制和ATP酶激活。
