Primate Biology Laboratory, ICMR-National Institute for Research in Reproductive Health (ICMR-NIRRH), Indian Council of Medical Research (ICMR), Mumbai, India.
Biochemistry Laboratory, ICMR-National Institute for Research in Reproductive Health (ICMR-NIRRH), Indian Council of Medical Research (ICMR), Mumbai, India.
Mol Carcinog. 2019 Nov;58(11):2077-2090. doi: 10.1002/mc.23099. Epub 2019 Aug 14.
The plasma membrane (PM) is considered as a major druggable site. More than 50% of the existing drugs target PM proteins. In the wake of emerging data indicating a key role of estrogens in prostate cancer (PCa) pathogenesis, the study was undertaken to explore whether the estrogen binding sites exist on the PM and if such sites are functionally relevant in PCa. Estradiol (E2) binding to the PM was detected in androgen-dependent (LNCaP), androgen-independent (PC3, DU145) PCa cell lines, nontumorigenic (RWPE1) prostate epithelial cell line, and rat prostate cells. Conventional estrogen receptors (nuclear estrogen receptors), known for their nuclear localization, were detected in the PM enriched extracts. This was indirectly confirmed by reduced localization of ERs on the PM of cells, silenced for the expression of their cognate genes. Further, unlike cell-permeable E2, stimulation with cell-impermeable estradiol (E2-BSA) did not induce proliferation in LNCaP cells. However, stimulation with E2-BSA led to alterations in the phosphorylation status of several kinases including GSK3 and AKT, along with the hyperphosphorylation of cytoskeletal proteins such as β-actin and cytokeratin 8 in LNCaP. This was accompanied by epithelial-to-mesenchymal (EMT) features such as increased migration and invasion; higher vimentin expression, and a concomitant decrease in the E-cadherin expression. These effects were not observed in RWPE1 cells. Interestingly, cell-permeable E2 failed to induce EMT in PCa cells. This in vitro study is the first to suggest that the PM-initiated estrogen signaling contributes to higher invasiveness in PCa cells. Plasma membrane ERs may act as novel targets for PCa therapeutics.
质膜（PM）被认为是一个主要的可药物作用位点。超过 50%的现有药物靶向 PM 蛋白。鉴于新兴数据表明雌激素在前列腺癌（PCa）发病机制中起关键作用，本研究旨在探讨雌激素结合位点是否存在于质膜上，以及这些结合位点在 PCa 中是否具有功能相关性。在雄激素依赖性（LNCaP）、雄激素非依赖性（PC3、DU145）PCa 细胞系、非肿瘤性（RWPE1）前列腺上皮细胞系和大鼠前列腺细胞中检测到雌二醇（E2）与 PM 的结合。众所周知，常规雌激素受体（核雌激素受体）定位于核内，在富含 PM 的提取物中也有检测到。通过沉默其同源基因表达的细胞中 ER 在 PM 上的定位减少，间接证实了这一点。此外，与细胞通透性 E2 不同，用细胞通透性差的雌二醇（E2-BSA）刺激不会诱导 LNCaP 细胞增殖。然而，E2-BSA 的刺激导致包括 GSK3 和 AKT 在内的几种激酶的磷酸化状态发生改变，以及细胞骨架蛋白如β-肌动蛋白和细胞角蛋白 8 的过度磷酸化，这伴随着上皮到间充质（EMT）特征的改变，如迁移和侵袭增加；波形蛋白表达增加，同时 E-钙黏蛋白表达减少。这些变化在 RWPE1 细胞中没有观察到。有趣的是，细胞通透性 E2 未能诱导 PCa 细胞发生 EMT。这项体外研究首次表明，PM 启动的雌激素信号有助于 PCa 细胞更高的侵袭性。质膜 ER 可能成为 PCa 治疗的新靶点。
