Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
FASEB J. 2020 Apr;34(4):5975-5992. doi: 10.1096/fj.201902555R. Epub 2020 Feb 20.
ADP-ribosylation factor 6 (ARF6) is a well-studied protein that is involved in multiple biological functions including cell migration and invasion. The mechanism by which ARF6 regulates the migration and invasion of upper tract urothelial carcinoma (UTUC) is still unknown. MiR-145-5p is a tumor suppressor microRNA, which is downregulated in several cancer types. We aimed to elucidate the molecular mechanism underlying the regulation of ARF6 by miR-145-5p in UTUC. ARF6 expression was observed to be higher in UTUC tissues than paired adjacent normal tissues. A reverse correlation between ARF6 and miR-145-5p was found in UTUC tissues. MiR-145-5p inhibited ARF6 expression by directly targeting its 3'-UTR. The functional studies indicated that ARF6 expression reversed the miR-145-5p-reduced tumor cell migration and invasion. Notably, miR-145-5p reduced MMP2, N-cadherin, FAK and MMP7, and elevated E-cadherin protein levels in vitro; however, the above effects were reversed by ARF6. Further, the expression of epithelial-to-mesenchymal transition (EMT) markers and cell invasion was suppressed by knocking down MMP7 in UTUC cells. These findings suggest that miR-145-5p may suppress UTUC cell motility and invasion by targeting ARF6/MMP7 through EMT.
ADP-核糖基化因子 6 (ARF6) 是一种研究较为深入的蛋白质，参与多种生物学功能，包括细胞迁移和侵袭。ARF6 调节上尿路上皮癌 (UTUC) 迁移和侵袭的机制尚不清楚。miR-145-5p 是一种肿瘤抑制 microRNA，在几种癌症类型中下调。我们旨在阐明 miR-145-5p 对 UTUC 中 ARF6 调节的分子机制。ARF6 在 UTUC 组织中的表达高于配对的相邻正常组织。在 UTUC 组织中发现 ARF6 与 miR-145-5p 呈负相关。miR-145-5p 通过直接靶向其 3'-UTR 抑制 ARF6 表达。功能研究表明，ARF6 表达逆转了 miR-145-5p 减少的肿瘤细胞迁移和侵袭。值得注意的是，miR-145-5p 在体外降低了 MMP2、N-钙粘蛋白、FAK 和 MMP7 的蛋白水平，并上调了 E-钙粘蛋白的蛋白水平；然而，ARF6 逆转了上述作用。此外，通过在 UTUC 细胞中敲低 MMP7，抑制了上皮-间质转化 (EMT) 标志物的表达和细胞侵袭。这些发现表明，miR-145-5p 可能通过 EMT 靶向 ARF6/MMP7 抑制 UTUC 细胞的迁移和侵袭。
