Laboratory of Biopharmaceutics, Department of Pharmacology, Takasaki University of Health and Welfare, Takasaki, Gunma, Japan.
Laboratory of Clinical Pharmacokinetics, Graduate School of Pharmaceutical Sciences, Takasaki University of Health and Welfare, Takasaki, Gunma, Japan.
J Pharm Pharmacol. 2020 Apr;72(4):575-582. doi: 10.1111/jphp.13225. Epub 2020 Jan 24.
Ezrin (Ezr), radixin (Rdx) and moesin (Msn) (ERM) proteins anchor other proteins to the cell membrane, serving to regulate their localization and function. Here, we examined whether ERM proteins functionally regulate breast cancer resistance protein (BCRP) and P-glycoprotein in cell lines derived from lung, intestinal and renal cancers.
ERM proteins were each silenced with appropriate siRNA. BCRP and P-gp functions were evaluated by means of efflux and uptake assays using 7-ethyl-10-hydroxycamptothecin (SN-38) and rhodamine123 (Rho123) as specific substrates, respectively, in non-small cell lung cancer HCC827 cells, intestinal cancer Caco-2 cells and renal cancer Caki-1 cells.
In HCC827 cells, the efflux rates of SN-38 and Rho123 were significantly decreased by knockdown of Ezr or Msn, but not Rdx. However, BCRP function was unaffected by Ezr or Rdx knockdown in Caco-2 cells, which do not express Msn. In Caki-1 cells, Rdx knockdown increased the intracellular SN-38 concentration, while knockdown of Ezr or Msn had no effect.
Our findings indicate that regulation of BCRP and P-gp functions by ERM proteins is organ-specific. Thus, if the appropriate ERM protein(s) are functionally suppressed, accumulation of BCRP or P-gp substrates in lung, intestine or kidney cancer tissue might be specifically increased.
埃兹蛋白（Ezr）、根蛋白（Rdx）和膜突蛋白（Msn）（ERM）蛋白将其他蛋白锚定在细胞膜上，以调节它们的定位和功能。在这里，我们研究了 ERM 蛋白是否在来源于肺癌、肠癌和肾癌的细胞系中功能调节乳腺癌耐药蛋白（BCRP）和 P-糖蛋白。
用适当的 siRNA 沉默 ERM 蛋白。通过使用 7-乙基-10-羟基喜树碱（SN-38）和罗丹明 123（Rho123）作为特异性底物的外排和摄取测定，分别在非小细胞肺癌 HCC827 细胞、肠癌细胞 Caco-2 细胞和肾癌细胞 Caki-1 细胞中评估 BCRP 和 P-糖蛋白的功能。
在 HCC827 细胞中，SN-38 和 Rho123 的外排率明显降低，通过 Ezr 或 Msn 的敲低，但 Rdx 则没有。然而，在不表达 Msn 的 Caco-2 细胞中，BCRP 功能不受 Ezr 或 Rdx 敲低的影响。在 Caki-1 细胞中，Rdx 的敲低增加了细胞内 SN-38 的浓度，而 Ezr 或 Msn 的敲低则没有影响。
我们的研究结果表明，ERM 蛋白对 BCRP 和 P-糖蛋白功能的调节是器官特异性的。因此，如果适当的 ERM 蛋白（s）被功能抑制，BCRP 或 P-糖蛋白底物在肺癌、肠癌或肾癌组织中的积累可能会特异性增加。
