熊果酸诱导的 AMP 激活的蛋白激酶(AMPK)激活有助于抑制人膀胱癌 T24 细胞的生长和诱导其凋亡。

Ursolic acid-induced AMP-activated protein kinase (AMPK) activation contributes to growth inhibition and apoptosis in human bladder cancer T24 cells.

机构信息

Department of Urology, The Military General Hospital of Beijing PLA, Beijing 100700, China.

出版信息

Biochem Biophys Res Commun. 2012 Mar 23;419(4):741-7. doi: 10.1016/j.bbrc.2012.02.093. Epub 2012 Feb 24.

Abstract

Ursolic acid (UA) has shown the anti-tumor properties against a number of human cancers both in vivo and in vitro, however, its effect in bladder cancer and the corresponding mechanisms of action remain largely unknown. Here we found that UA dose-dependently induced growth inhibition and apoptosis in human bladder cancer T24 cells, and activation of AMP-activated protein kinase (AMPK) may contribute to the process. Our Western-blot results demonstrated a significant AMPK activation after UA treatment in T24 cells. Notably, knockdown of AMPKα by the targeted shRNA largely inhibited UA-induced T24 cell growth inhibition and apoptosis, while an AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) or a constitutively active form of AMPK mimic UA's effect. We found the ceramide level was increased after UA treatment in T24 cells, and UA-induced AMPK activation and T24 cell apoptosis were inhibited by ceramide synthase inhibitor fumonisin B1, and was enhanced by exogenously adding cell permeable short-chain ceramide (C6), suggesting that ceramide might serve as an upstream signal for AMPK activation. Further, activation of AMPK by UA promoted c-Jun N-terminal kinase (JNK) activation, but inhibited mTOR complex 1 (mTORC1) signaling to cause survivin down-regulation. Our study suggests that activation of AMPK by UA contributes to growth inhibition and apoptosis in human bladder cancer cells.

摘要

熊果酸(UA)在体内和体外均显示出对多种人类癌症的抗肿瘤特性,但它在膀胱癌中的作用及其相应的作用机制在很大程度上仍然未知。在这里,我们发现 UA 可剂量依赖性地诱导人膀胱癌 T24 细胞的生长抑制和凋亡,而 AMP 激活的蛋白激酶(AMPK)的激活可能有助于这一过程。我们的 Western blot 结果表明,UA 处理后 T24 细胞中 AMPK 明显激活。值得注意的是,靶向 shRNA 敲低 AMPKα 可显著抑制 UA 诱导的 T24 细胞生长抑制和凋亡,而 AMPK 激活剂 5-氨基咪唑-4-甲酰胺-1-β-D-核糖呋喃糖苷(AICAR)或组成型激活形式的 AMPK 模拟 UA 的作用。我们发现 UA 处理后 T24 细胞中的神经酰胺水平增加,UA 诱导的 AMPK 激活和 T24 细胞凋亡被神经酰胺合酶抑制剂伏马菌素 B1 抑制,并通过体外添加细胞可渗透的短链神经酰胺(C6)增强,表明神经酰胺可能作为 AMPK 激活的上游信号。此外,UA 激活 AMPK 可促进 c-Jun N 端激酶(JNK)的激活,但抑制 mTOR 复合物 1(mTORC1)信号传导导致 survivin 下调。我们的研究表明,UA 激活 AMPK 有助于人膀胱癌细胞的生长抑制和凋亡。

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