Department of General Surgery, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, P.R. China.
Mol Med Rep. 2018 Oct;18(4):3751-3759. doi: 10.3892/mmr.2018.9363. Epub 2018 Aug 8.
Achaete‑scute homolog 2 (ASCL2), a basic helix‑loop‑helix transcription factor, serves an essential role in the maintenance of adult intestinal stem cells and the growth of gastric cancer (GC). However, the function of ASCL2 in the metastasis of GC is poorly understood. The present study aimed to evaluate the effect of ASCL2 expression on gastric tumor metastasis. ASCL2 protein expression was detected in 32 cases of gastric metastasis and its relevant primary tumors using western blotting and immunohistochemistry. The data suggested that the expression of ASCL2 was highest in metastatic tumors, among adjacent normal tissues, primary gastric tumors and gastric metastatic tumors. Furthermore, ASCL2‑overexpressing GC cell lines MKN1‑ASCL2 and SNU16‑ASCL2 were established. An in vitro assay suggested that microRNA 223 (miR223) expression was downregulated following ASCL2 overexpression, and that the expression of the epithelium‑associated protein E‑cadherin was significantly decreased, while a series of mesenchyme‑associated proteins, including zinc finger E‑box‑binding homeobox 1 (Zeb‑1), twist‑related protein 1, integrin, vimentin, 72 kDa type IV collagenase and matrix metalloproteinase‑9 were upregulated in ASCL2‑overexpressing cells. Overexpression of miR223 attenuated the epithelial‑mesenchymal transition (EMT)‑promoting effect induced by ASCL2 expression. In addition, the results of the chromatin immunoprecipitation and luciferase reporter gene assays indicated that ASCL2 was able to interact with the promoter of pre‑miR223, and to inhibit the maturation of miR223, which may interact with the 3' untranslated region of Zeb‑1 and inhibit EMT in tumor cells. The results of the present study demonstrated that ASCL2 was able to downregulate the expression level of miR223, contribute to EMT and promote gastric tumor metastasis, which indicated that ASCL2 may serve as a therapeutic target in the treatment of GC.
achaete-scute 同源物 2 (ASCL2) 是一种碱性螺旋-环-螺旋转录因子，在维持成人肠道干细胞和胃癌 (GC) 生长中发挥着重要作用。然而，ASCL2 在 GC 转移中的功能尚不清楚。本研究旨在评估 ASCL2 表达对胃肿瘤转移的影响。采用 Western blot 法和免疫组织化学法检测 32 例胃转移及其相关原发肿瘤中 ASCL2 蛋白的表达。结果表明，在转移瘤中 ASCL2 表达最高，在相邻正常组织、原发胃癌和胃转移瘤中表达最低。此外，建立了 ASCL2 过表达 GC 细胞系 MKN1-ASCL2 和 SNU16-ASCL2。体外试验表明，ASCL2 过表达后 microRNA 223 (miR223) 表达下调，上皮相关蛋白 E-钙黏蛋白表达明显下调，而一系列间质相关蛋白，包括锌指 E-盒结合同源盒 1 (Zeb-1)、 twist 相关蛋白 1、整合素、波形蛋白、72 kDa 型 IV 胶原酶和基质金属蛋白酶-9 表达上调。miR223 的过表达减弱了 ASCL2 表达诱导的上皮-间充质转化 (EMT)。此外，染色质免疫沉淀和荧光素酶报告基因检测结果表明，ASCL2 能够与 pre-miR223 的启动子相互作用，并抑制 miR223 的成熟，这可能与 Zeb-1 的 3'UTR 相互作用并抑制肿瘤细胞的 EMT。本研究结果表明，ASCL2 能够下调 miR223 的表达水平，促进 EMT 并促进胃肿瘤转移，这表明 ASCL2 可能成为治疗 GC 的靶点。
