Ursolic acid (UA), a natural pentacyclic triterpenoid, is known to exhibit various biological activities and anticancer effects. However, the underlying anticancer mechanism is not fully understood to date. The present study aimed to investigate the antimetastatic effect of UA through ADP‑ribosylation factor like GTPase 4C (ARL4C) in colon cancer. A lung metastasis model of colon cancer in nude mice was established through tail vein injection. A Cell Counting Kit‑8 assay was used to investigate the proliferation of colon cancer cells. Transwell assays were used to detect cell migration and invasion. The expression levels of proteins including ARL4C, matrix metallopeptidase 2 (MMP2), phosphorylated (p)‑AKT and p‑mTOR were measured using western blot analysis. Immunohistochemistry was used to determine the protein expression level in tissues. ARL4C ubiquitination levels were analysed using immunoprecipitation and western blotting. The results indicated that UA inhibits the metastasis of colon cancer in vivo and in vitro. The expression of ARL4C in human colon cancer tissue was significantly higher than that in adjacent tissues and its high expression level was associated with lymph node metastases and tumour stage. UA treatment significantly decreased ARL4C and MMP2 protein levels and inhibited the AKT/mTOR signalling pathway. Overexpression of ARL4C reversed the inhibitory effect of UA on the invasion and migration of HCT‑116 and SW480 cells, as well as the expression and secretion of MMP2 protein. In addition, UA and an AKT signalling pathway inhibitor (LY294002) induced the ubiquitination of the ARL4C protein, which was reversed by a proteasome inhibitor (MG‑132). Collectively, it was revealed in the present study that UA served as a novel solution to relieve colon cancer metastasis by inducing the ubiquitination‑mediated degradation of ARL4C by modulating the AKT signalling pathway. Thus, UA may be a promising treatment option to prolong the survival of patients with colon cancer metastasis.

中文翻译：

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熊果酸通过下调 ARL4C 表达抑制结肠癌的转移。

熊果酸（UA）是一种天然五环三萜类化合物，具有多种生物活性和抗癌作用。然而，迄今为止，潜在的抗癌机制尚未完全了解。本研究旨在探讨 UA 通过 GTPase 4C (ARL4C) 等 ADP 核糖基化因子对结肠癌的抗转移作用。通过尾静脉注射建立裸鼠结肠癌肺转移模型。使用细胞计数试剂盒 8 检测来研究结肠癌细胞的增殖。Transwell实验用于检测细胞迁移和侵袭。使用蛋白质印迹分析测量 ARL4C、基质金属肽酶 2 (MMP2)、磷酸化 (p)-AKT 和 p-mTOR 等蛋白质的表达水平。免疫组织化学用于测定组织中的蛋白质表达水平。使用免疫沉淀和蛋白质印迹分析 ARL4C 泛素化水平。结果表明，UA在体内和体外均具有抑制结肠癌转移的作用。ARL4C在人结肠癌组织中的表达量显着高于癌旁组织，其高表达水平与淋巴结转移和肿瘤分期相关。UA 治疗显着降低 ARL4C 和 MMP2 蛋白水平并抑制 AKT/mTOR 信号通路。ARL4C的过表达逆转了UA对HCT-116和SW480细胞侵袭和迁移以及MMP2蛋白表达和分泌的抑制作用。此外，UA 和 AKT 信号通路抑制剂 (LY294002) 诱导 ARL4C 蛋白泛素化，蛋白酶体抑制剂 (MG-132) 可逆转这一现象。总的来说，本研究表明，UA 通过调节 AKT 信号通路诱导泛素化介导的 ARL4C 降解，成为缓解结肠癌转移的新解决方案。因此，UA可能是延长结肠癌转移患者生存期的有前途的治疗选择。