PAK inhibitor FRAX486 decreases the metastatic potential of triple-negative breast cancer cells by blocking autophagy,British Journal of Cancer

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PAK inhibitor FRAX486 decreases the metastatic potential of triple-negative breast cancer cells by blocking autophagy
British Journal of Cancer ( IF 6.4 ) Pub Date : 2023-12-18 , DOI: 10.1038/s41416-023-02523-4
Liang Lyu ₁ , Haiyan Li ₁ , Kefeng Lu ₁ , Shu Jiang ₁ , Huihui Li _{1,

2}

Affiliation

Background

Triple-negative breast cancer (TNBC) is a unique breast cancer subtype with a high risk of metastasis and recurrence and a poor prognosis. Epithelial-mesenchymal transition (EMT) endows epithelial cells with the ability to move to distant sites, which is essential for the metastasis of TNBC to organs, including the lung. Autophagy, an intracellular degradation process that involves formation of double-layered lipid autophagosomes that transport cytosolic cargoes into lysosomes via autophagosome–lysosome fusion, is involved in various diseases, including cancer and neurodegenerative, metabolic, cardiovascular, and infectious diseases. The relationship between autophagy and cancer has become relatively clear. However, research on pharmacological drugs that block cancer EMT by targeting autophagy is still in the initial stages. Therefore, the re-evaluation of old drugs for their potential in blocking both autophagy and EMT was conducted.

Methods

More than 2000 small molecule chemicals were screened for dual autophagy/EMT inhibitors, and FRAX486 was identified as the best candidate inhibitor of autophagy/EMT. The functions of FRAX486 in TNBC metastasis were detected by CCK-8, migration and wound healing assays. The effects of FRAX486 on autophagy and its target PAK2 were determined by immunoblotting, immunofluorescence, immunoprecipitation analysis and transmission electron microscopy. The findings were validated in mouse models.

Results

Here, we report that FRAX486, a potent P21-activated kinase 2 (PAK2) inhibitor, facilitates TNBC suppression both in vitro and in vivo by blocking autophagy. Mechanistically, FRAX486 inhibits autophagy in TNBC cells by targeting PAK2, leading to the ubiquitination and proteasomal degradation of STX17, which mediates autophagosome–lysosome fusion. The inhibition of autophagy by FRAX486 causes upregulation of the epithelial marker protein E-cadherin and thus suppresses the migration and metastasis of TNBC cells.

Conclusions

The effects of FRAX486 on TNBC metastasis suppression were verified to be dependent on PAK2 and autophagy inhibition. Together, our results provide a molecular basis for the application of FRAX486 as a potential treatment for inhibiting the metastasis of TNBC.

中文翻译：

PAK 抑制剂 FRAX486 通过阻断自噬降低三阴性乳腺癌细胞的转移潜力

背景

三阴性乳腺癌（TNBC）是一种独特的乳腺癌亚型，转移和复发风险高，预后差。上皮-间质转化（EMT）赋予上皮细胞移动到远处的能力，这对于 TNBC 转移到包括肺在内的器官至关重要。自噬是一种细胞内降解过程，涉及形成双层脂质自噬体，通过自噬体-溶酶体融合将胞质货物转运到溶酶体中，与多种疾病有关，包括癌症和神经退行性疾病、代谢性疾病、心血管疾病和传染病。自噬与癌症的关系已经比较明确。然而，通过靶向自噬来阻断癌症 EMT 的药物研究仍处于初始阶段。因此，重新评估了旧药阻断自噬和 EMT 的潜力。

方法

筛选了2000多种小分子化学物质的自噬/EMT双重抑制剂，FRAX486被确定为自噬/EMT的最佳候选抑制剂。通过CCK-8、迁移和伤口愈合实验检测FRAX486在TNBC转移中的功能。通过免疫印迹、免疫荧光、免疫沉淀分析和透射电子显微镜测定了 FRAX486 对自噬及其靶标 PAK2 的影响。研究结果在小鼠模型中得到了验证。

结果

在此，我们报道 FRAX486 是一种有效的 P21 激活激酶 2 (PAK2) 抑制剂，通过阻断自噬促进体外和体内 TNBC 抑制。从机制上讲，FRAX486 通过靶向 PAK2 抑制 TNBC 细胞中的自噬，导致 STX17 泛素化和蛋白酶体降解，从而介导自噬体-溶酶体融合。 FRAX486 对自噬的抑制导致上皮标记蛋白 E-钙粘蛋白上调，从而抑制 TNBC 细胞的迁移和转移。