Alam Khondoker, Farasyn Taleah, Ding Kai, Yue Wei
Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.
Department of Biostatistics and Epidemiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.
Drug Metab Lett. 2018;12(1):24-32. doi: 10.2174/1872312812666180326110146.
Membrane transport protein organic anion transporting polypeptide (OATP) 1B3 mediates the cellular uptake of many clinically important drugs including anti-cancer drugs (e.g., paclitaxel). In addition to the well-recognized hepatic expression and function of OATP1B3 [herein named liver-type (Lt) OATP1B3], OATP1B3 also expresses in cancers and has been postulated to play a role in cancer therapy, presumably by facilitating the influx of anti-cancer drugs. Recently, a cancer type (Ct)-OATP1B3 mRNA variant was identified in colon and lung cancer tissues, which encodes truncated Ct-OATP1B3 with negligible transport activity. Other than in colon and lung cancers, reports on mRNA expression of OATP1B3 in other cancers cannot distinguish between the Ltand Ct-OATP1B3.
The current studies were designed to characterize the expression of Lt- and Ct-OATP1B3 mRNA in ovarian, prostate, bladder, breast, and lung tissues.
Lt- and Ct-OATP1B3 isoform-specific PCR primers were utilized to determine the mRNA levels of Lt- and Ct-OATP1B3, respectively. An expression vector expressing green fluorescent protein (GFP)-tagged Lt-OATP1B3 was transiently transfected into the ovarian cancer cell line SKOV3. Confocal live-cell microscopy was utilized to determine the localization of GFP-Lt-OATP1B3 in SKOV3 cells.
For the first time, Lt-OATP1B3 mRNA was detected in ovarian, prostate, bladder and breast cancers. The localization of GFP-Lt-OATP1B3 on the plasma membrane of SKOV3 cells after transient transfection was readily detected by confocal microscopy.
Our findings are supportive of the potential role of Lt-OATP1B3 in cancer cells.
膜转运蛋白有机阴离子转运多肽（OATP）1B3介导许多临床重要药物（包括抗癌药物，如紫杉醇）的细胞摄取。除了广为人知的OATP1B3在肝脏中的表达和功能（在此命名为肝型（Lt）OATP1B3）外，OATP1B3也在癌症中表达，并被推测在癌症治疗中发挥作用，可能是通过促进抗癌药物的流入。最近，在结肠癌和肺癌组织中鉴定出一种癌症类型（Ct）-OATP1B3 mRNA变体，其编码具有可忽略不计转运活性的截短型Ct-OATP1B3。除了在结肠癌和肺癌中，关于OATP1B3在其他癌症中的mRNA表达的报道无法区分Lt-和Ct-OATP1B3。
当前研究旨在表征Lt-和Ct-OATP1B3 mRNA在卵巢、前列腺、膀胱、乳腺和肺组织中的表达。
利用Lt-和Ct-OATP1B3同工型特异性PCR引物分别测定Lt-和Ct-OATP1B3的mRNA水平。将表达绿色荧光蛋白（GFP）标记的Lt-OATP1B3的表达载体瞬时转染到卵巢癌细胞系SKOV3中。利用共聚焦活细胞显微镜确定GFP-Lt-OATP1B3在SKOV3细胞中的定位。
首次在卵巢癌、前列腺癌、膀胱癌和乳腺癌中检测到Lt-OATP1B3 mRNA。共聚焦显微镜很容易检测到瞬时转染后GFP-Lt-OATP1B3在SKOV3细胞质膜上的定位。
我们的研究结果支持Lt-OATP1B3在癌细胞中的潜在作用。
