School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, 632 014, India.
Department of Chemical Engineering, Indian Institute of Technology Bombay Powai, Mumbai, Maharashtra, 400076, India.
Mol Cell Biochem. 2018 Dec;449(1-2):91-104. doi: 10.1007/s11010-018-3346-4. Epub 2018 Apr 11.
Treatment with doxorubicin (dox) and emodin, separately and together, under normoxic and hypoxia-like conditions induced by CoCl, led to greater intracellular compound accumulation over 10 h post-addition in the presence of CoCl in lung adenocarcinoma (A549) and colorectal carcinoma (HCT-15) cell lines. Confocal microscopy revealed that emodin, by itself, showed high cytosolic distribution in both cell lines, at 40 min post-addition but had entered the nuclei by 2 h, while dox entered the nuclei by 40 min. Both compounds modulated the expression of the efflux transporters (PgP, ABCG2, or MRP1-4) and the endocytic receptor, low-density lipoprotein receptor-related protein 1 (LRP1), to different extents under the study conditions. Efflux transporter upregulation was linked to lower intracellular compound levels due to greater efflux. Increased dox accumulation was accompanied by unaltered expression or upregulation of LRP1 in A549 cells. In both cell lines, increased accumulation of dox and emodin was observed whenever LRP1 and the efflux transporters known to transport dox and emodin were all up- or downregulated concomitantly. Increased growth inhibition was linked to co-treatment with dox and emodin and with increased ligand accumulation. The results presented in this study raise the hypothesis that higher production of LRP1 protein may be associated with higher endocytosis of upregulated transporter proteins at the cell surface, and hence, increased dox and emodin accumulation and growth inhibition. If so, elevation of LRP1 expression may be a useful target for interventions to promote the efficacy of these and other anticancer drugs.
在常氧和 CoCl 诱导的缺氧样条件下，分别用阿霉素（dox）和大黄素处理，以及联合处理，可导致在 CoCl 存在的情况下，肺腺癌细胞（A549）和结直肠癌细胞（HCT-15）在加入化合物后 10 小时内细胞内化合物积累增加。共焦显微镜显示，大黄素本身在两种细胞系中都具有高细胞质分布，在加入后 40 分钟，但在 2 小时内进入细胞核，而 dox 在 40 分钟内进入细胞核。在研究条件下，两种化合物都不同程度地调节了外排转运蛋白（PgP、ABCG2 或 MRP1-4）和内吞受体，低密度脂蛋白受体相关蛋白 1（LRP1）的表达。由于外排增加，外排转运蛋白上调与细胞内化合物水平降低有关。在 A549 细胞中， dox 的积累增加伴随着 LRP1 表达不变或上调。在两种细胞系中，只要同时上调或下调已知转运 dox 和大黄素的 LRP1 和外排转运蛋白，就观察到 dox 和大黄素的积累增加。增加的生长抑制与 dox 和大黄素的联合治疗以及配体积累增加有关。本研究结果提出了一种假设，即 LRP1 蛋白的高产量可能与细胞表面上调的转运蛋白的内吞增加有关，因此 dox 和大黄素的积累和生长抑制增加。如果是这样，升高 LRP1 表达可能是提高这些和其他抗癌药物疗效的有用干预目标。
