MiR-375 frequently downregulated in gastric cancer inhibits cell proliferation by targeting JAK2

新兴的证据与肿瘤开发和前进显示出异常地表示的 microRNAs (miRNAs ) 的协会。然而，很少在胃的 carcinogenesis 对 miRNAs 的潜在的角色被知道。这里，我们执行了 miRNA microarray 屏蔽在配对的胃的癌症和他们的邻近的 nontumor 纸巾表示并且发现 miR-375 是的 miRNAs 差别极大地在胃的癌症纸巾的 downregulated。量的即时 PCR 分析证实那 miR-375 表情显著地从经历胃的切除术的病人与他们的 nontumor 对应物相比在超过 90% 主要胃的癌症被减少。miR-375 的 Overexpression 显著地在 vitro 并且在 vivo 禁止了胃的癌症房间增长。在胃的癌症房间的 miR-375 的强迫的表示显著地减少了 Janus kinase 的蛋白质水平 2 ( JAK2 )并且镇压带 JAK2 的 3 鈥? untranslated 区域的一个酶记者的活动，被预言的 miR-375-binding 地点的变化废除，显示那 JAK2 可以是 miR-375 目标基因。由由 RNAi 的 JAK2 的 AG490 或 silencing 的 JAK2 活动的任何一个抑制压制了类似于 miR-375 overexpression 的胃的癌症房间增长。而且， JAK2 的宫外的表示能部分颠倒 miR-375 引起的房间增长的抑制。最后，我们在胃的癌症发现了在 miR-375 表示和 JAK2 蛋白质水平之间的重要反的关联。因此，这些数据建议 miR-375 可以作为肿瘤 suppressor 工作由指向 JAK2 oncogene 潜在地调整胃的癌症房间增长，含有在胃的癌症的致病的 miR-375 的一个角色。

Emerging evidence has shown the association of aberrantly expressed microRNAs （miRNAs） with tumor development and progression. However, little is known about the potential role of miRNAs in gastric carcinogenesis. Here, we performed miRNA microarray to screen miRNAs differentially expressed in the paired gastric cancer and their adjacent nontumor tissues and found that miR-375 was greatly downregulated in gastric cancer tissues. Quantitative real-time PCR analysis verified that miR-375 expression was significantly decreased in more than 90% of primary gastric cancers compared with their nontumor counterparts from patients undergoing gastric resection. Overexpression of miR-375 significantly inhibited gastric cancer cell proliferation in vitro and in vivo. Forced expression of miR-375 in gastric cancer cells significantly reduced the protein level of Janus kinase 2 （JAK2） and repressed the activity of a luciferase reporter carrying the 3＇-untranslated region of JAK2, which was abolished by mutation of the predicted miR-375-binding site, indicating that JAK2 may be a miR-375 target gene. Either inhibition of JAK2 activity by AG490 or silencing of JAK2 by RNAi suppressed gastric cancer cell proliferation resembling that of miR-375 overexpression. Moreover, ectopic expression of JAK2 can partially reverse the inhibition of cell proliferation caused by miR-375. Finally, we found a significant inverse correlation between miR-375 expression and JAK2 protein level in gastric cancer. Thus, these data suggest that miR-375 may function as a tumor suppressor to regulate gastric cancer cell proliferation potentially by targeting the JAK2 oncogene, implicating a role of miR-375 in the pathogenesis of gastric cancer.