Zhao Yue, Dong Qianze, Wang Enhua
Department of Pathology, The First Affiliated Hospital and College of Basic Medical Sciences, China Medical University, Shenyang, People's Republic of China.
Onco Targets Ther. 2017 Feb 20;10:1049-1058. doi: 10.2147/OTT.S123324. eCollection 2017.
MicroRNA-320 (miR-320) downregulation has been reported in several human cancers. Until now, its expression pattern and biological roles in human cancer remain unknown. This study aims to clarify its clinical expression pattern and biological function in gastric cancers. We found miR-320 level was downregulated in gastric cancer tissues. miR-320 mimic was transfected in SGC-7901 cells with low endogenous expression. miR-320 inhibitor was used in BGC-823 cells with high endogenous expression. We found that miR-320 inhibited SGC-7901 proliferation and invasion, with decreased expression of cyclin D1 and MMP9 at both mRNA and protein levels. We also found that miR-320 mimic downregulated chemoresistance and cell survival of gastric cancer cells when treated with 5-fluorouracil. miR-320 inhibitor displayed the opposite effects in BGC-823 cell line. In addition, we discovered that miR-320 mimic could inhibit AKT and ERK activity. By using luciferase reporter assay, we found that CRKL serves as the target of miR-320. miR-320 mimic downregulated CRKL expression, whereas miR-320 inhibitor upregulated CRKL expression. miR-320 suppressed CRKL-3'-untranslated region reporter intensity in SGC-7901 cells. Furthermore, CRKL depletion abrogated the effects of miR-320. In gastric cancer tissues, we observed a negative correlation between CRKL and miR-320. In conclusion, our study demonstrated that downregulation of miR-320 was closely related with malignant progression of gastric cancer. miR-320 inhibits proliferation, invasion, and chemoresistance through ERK and AKT signaling by targeting CRKL.
已有报道称，在多种人类癌症中，微小RNA-320（miR-320）表达下调。迄今为止，其在人类癌症中的表达模式和生物学作用仍不清楚。本研究旨在阐明其在胃癌中的临床表达模式及生物学功能。我们发现，胃癌组织中miR-320水平下调。将miR-320模拟物转染至内源性表达较低的SGC-7901细胞中。将miR-320抑制剂用于内源性表达较高的BGC-823细胞。我们发现，miR-320抑制SGC-7901细胞的增殖和侵袭，细胞周期蛋白D1和基质金属蛋白酶9在mRNA和蛋白质水平的表达均降低。我们还发现，用5-氟尿嘧啶处理时，miR-320模拟物可下调胃癌细胞的化疗耐药性和细胞存活率。miR-320抑制剂在BGC-823细胞系中表现出相反的作用。此外，我们发现miR-320模拟物可抑制AKT和ERK活性。通过荧光素酶报告基因检测，我们发现CRKL是miR-320的靶标。miR-320模拟物下调CRKL表达，而miR-320抑制剂上调CRKL表达。miR-320抑制SGC-7901细胞中CRKL-3'-非翻译区报告基因的强度。此外，CRKL缺失消除了miR-320的作用。在胃癌组织中，我们观察到CRKL与miR-320呈负相关。总之，我们的研究表明，miR-320下调与胃癌的恶性进展密切相关。miR-通过靶向CRKL，通过ERK和AKT信号通路抑制增殖、侵袭和化疗耐药性。
