Zhu Junlan, Zheng Zhijian, Yin Zhangya, Ding Linchao, Li Congya, Wang Xuyao, Shu Peng, Zhou Jun, Liu Weihua, Liu Jian
Precision Medicine Laboratory, Beilun People's Hospital, Beilun Branch of the First Affiliated Hospital, School of Medicine, Zhejiang University, Ningbo, Zhejiang, China.
Department of Medical Oncology, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua, China.
Front Oncol. 2025 Mar 28;15:1565638. doi: 10.3389/fonc.2025.1565638. eCollection 2025.
MiR-146b has been identified as being overexpressed in human bladder cancer (BCa) and implicated in promoting cancer cell invasion. However, its specific involvement in BCa cell growth remains unclear. In this study, we demonstrate that the downregulation of miR-146b significantly suppresses tumorigenic growth of human BCa cells both and by inducing G0/G1 cell cycle arrest. Specifically, miR-146b inhibition resulted in a significant reduction in colony formation (p < 0.05) and anchorage-independent growth in both UMUC3 and T24T cells, as measured by soft agar assays, with three independent replicates for each experiment. Notably, Cyclin D1 protein plays a crucial role in miR-146b-induced BCa cell proliferation, as confirmed by Western blotting (p < 0.05), with each experiment performed in triplicate. Mechanistic investigations reveal that miR-146b reduces mothers against decapentaplegic homolog 4 (SMAD4) mRNA stability by directly binding to its 3' untranslated region (3'-UTR), leading to decreased SMAD4 expression. This reduction in SMAD4 levels promotes cellular myelocytomatosis (C-MYC) transcription, which in turn enhances Cyclin D1 transcription, ultimately facilitating BCa cell proliferation. The findings unveil a novel regulatory axis involving SMAD4/C-MYC/Cyclin D1 in mediating the oncogenic role of miR-146b in BCa cells. Statistical significance was determined using Student's t-test, with p-values <0.05 considered significant. Together with its previously established function in BCa invasion, the results highlight the potential for developing miR-146b-based therapeutic strategies for treating human BCa patients.
MiR-146b已被证实在人类膀胱癌（BCa）中过表达，并与促进癌细胞侵袭有关。然而，其在BCa细胞生长中的具体作用仍不清楚。在本研究中，我们证明miR-146b的下调通过诱导G0/G1期细胞周期停滞，显著抑制了人类BCa细胞的致瘤性生长。具体而言，通过软琼脂试验测量，miR-146b抑制导致UMUC3和T24T细胞的集落形成显著减少（p<0.05）以及非锚定依赖性生长减少，每个实验进行三次独立重复。值得注意的是，通过蛋白质免疫印迹法证实（p<0.05），细胞周期蛋白D1在miR-146b诱导的BCa细胞增殖中起关键作用，每个实验重复三次。机制研究表明，miR-146b通过直接结合其3'非翻译区（3'-UTR）降低母亲对五体不全同源物4（SMAD4）的mRNA稳定性，导致SMAD4表达降低。SMAD4水平的这种降低促进了细胞性骨髓细胞瘤（C-MYC）转录，进而增强了细胞周期蛋白D1转录，最终促进了BCa细胞增殖。这些发现揭示了一个涉及SMAD4/C-MYC/细胞周期蛋白D1的新调控轴，介导了miR-146b在BCa细胞中的致癌作用。使用学生t检验确定统计学显著性，p值<0.05被认为具有显著性。连同其先前在BCa侵袭中确立的功能，这些结果突出了开发基于miR-146b的治疗策略用于治疗人类BCa患者的潜力。
