Department of Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Department of Oncology, Gusu School, Suzhou Municipal Hospital, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou, China.
J Transl Med. 2023 Feb 3;21(1):77. doi: 10.1186/s12967-023-03933-x.
Chronic inflammation is a well-known risk factor for the development of gastric cancer (GC). Nevertheless, the molecular mechanisms underlying inflammation-related GC progression are incompletely defined.
Bioinformatic analysis was performed based on data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO), and the expression of miR-26b-5p in GC cells and tissues was validated by quantitative real-time PCR (qRT-PCR). Cell proliferation was examined through Cell Counting Kit-8 (CCK8), 5-Ethynyl-2'-deoxyuridine (EdU), colony formation, flow cytometry, and tumor xenografts. Correlation between miR-26b-5p and Cyclin dependent kinase 8 (CDK8) or Phosphodiesterase 4B (PDE4B) was analyzed by dual-luciferase reporter assays, qRT-PCR, and Western blot. The effect of miR-26b-5p on the Signal transducer and activator of transcription 3 (STAT3) pathway was investigated using Western blot, immunofluorescence (IF), and immunohistochemistry (IHC). The impact of STAT3 on miR-26b-5p was determined by dual-luciferase reporter assays and qRT-PCR.
The expression of miR-26b-5p was significantly downregulated in Helicobacter Pylori (H. pylori)-infected GC cells. The decreased expression of miR-26b-5p was also detected in GC cells and tissues compared to normal gastric epithelium cells (GES1) and normal adjacent gastric tissues. The low expression of miR-26b-5p promoted GC proliferation in vitro and in vivo and was related to the poor outcome of GC patients. In terms of mechanism, miR-26b-5p directly targeted PDE4B and CDK8, resulting in decreased phosphorylation and nuclear translocation of STAT3, which was associated with the regulation of GC proliferation by miR-26b-5p. Notably, miR-26b-5p was transcriptionally suppressed by STAT3, thus forming the miR-26b-5p-PDE4B/CDK8-STAT3 positive feedback loop.
The newly identified miR-26b-5p-PDE4B/CDK8-STAT3 feedback loop plays an important role in inflammation-related GC progression and may serve as a promising therapeutic target for GC.
慢性炎症是胃癌（GC）发展的一个众所周知的危险因素。然而，炎症相关 GC 进展的分子机制尚不完全明确。
基于癌症基因组图谱（TCGA）和基因表达综合数据库（GEO）的数据进行了生物信息学分析，并通过实时定量 PCR（qRT-PCR）验证了 miR-26b-5p 在 GC 细胞和组织中的表达。通过细胞计数试剂盒-8（CCK8）、5-乙炔基-2'-脱氧尿苷（EdU）、集落形成、流式细胞术和肿瘤异种移植检测细胞增殖。通过双荧光素酶报告分析、qRT-PCR 和 Western blot 分析 miR-26b-5p 与细胞周期蛋白依赖性激酶 8（CDK8）或磷酸二酯酶 4B（PDE4B）的相关性。使用 Western blot、免疫荧光（IF）和免疫组织化学（IHC）研究 miR-26b-5p 对信号转导和转录激活因子 3（STAT3）通路的影响。通过双荧光素酶报告分析和 qRT-PCR 确定 STAT3 对 miR-26b-5p 的影响。
miR-26b-5p 在 H. pylori 感染的 GC 细胞中表达明显下调。与正常胃上皮细胞（GES1）和正常相邻胃组织相比，GC 细胞和组织中 miR-26b-5p 的表达也降低。miR-26b-5p 的低表达促进了 GC 在体外和体内的增殖，并且与 GC 患者的不良预后相关。就机制而言，miR-26b-5p 直接靶向 PDE4B 和 CDK8，导致 STAT3 的磷酸化和核转位减少，这与 miR-26b-5p 对 GC 增殖的调节有关。值得注意的是，miR-26b-5p 被 STAT3 转录抑制，从而形成 miR-26b-5p-PDE4B/CDK8-STAT3 正反馈环。
新鉴定的 miR-26b-5p-PDE4B/CDK8-STAT3 反馈环在炎症相关 GC 进展中起重要作用，可能成为 GC 的有前途的治疗靶点。
