Mitochondrial PAK6 inhibits prostate cancer cell apoptosis via the PAK6-SIRT4-ANT2 complex
Mitochondrial PAK6 inhibits prostate cancer cell apoptosis via the PAK6-SIRT4-ANT2 complex
复制标题
线粒体 PAK6 通过 PAK6-SIRT4-ANT2 复合物抑制前列腺癌细胞凋亡
DOI：
10.7150/thno.42874
复制
发表时间：
2020-01-01
期刊：
影响因子：
12.4
通讯作者：
Li, Feng
中科院分区：
文献类型：
--
作者：
Li, Tingting;Li, Yang;Li, Feng
原理：P21激活激酶6（PAK 6）是II类PAKs家族的成员，该家族是保守的丝氨酸/苏氨酸激酶家族。虽然PAK 6对许多恶性肿瘤，特别是前列腺癌的作用已经研究了很长时间，但PAK 6在线粒体中的作用仍然未知。方法：采用免疫组织化学方法检测PAK 6、SIRT 4和ANT 2在前列腺癌及癌旁组织中的表达。用免疫荧光和免疫电镜观察PAK 6的亚细胞定位。进行免疫沉淀、免疫荧光和泛素化测定以确定PAK 6如何调节SIRT 4、SIRT 4如何调节ANT 2以及PAK 6如何调节ANT 2。采用流式细胞仪检测和异种移植模型评价ANT 2突变体表达对前列腺癌细胞周期和凋亡调控的影响。结果：PAK 6-SIRT 4-ANT 2复合物参与前列腺癌细胞线粒体凋亡。研究发现PAK 6主要定位于线粒体内膜，在其中PAK 6促进SIRT 4泛素介导的蛋白水解。此外，SIRT 4剥夺了K105处的ANT 2乙酰化，以促进其泛素化降解。因此，PAK 6通过PAK 6-SIRT 4-ANT 2途径调节ANT 2的乙酰化水平，以调节ANT 2的稳定性。同时PAK 6可直接磷酸化ANT 2的T107位点，抑制前列腺癌细胞凋亡。因此，ANT 2的磷酸化和去乙酰化修饰相互调节，导致体内肿瘤生长。一致地，这些临床前列腺癌组织评估揭示PAK 6与ANT 2表达正相关，但与SIRT 4负相关。结论：PAK 6-SIRT 4-ANT 2复合物在前列腺癌细胞凋亡中起重要作用。该复合物可能是前列腺癌治疗和预后的潜在生物标志物。
Rationale: P21-activated kinase 6 (PAK6) is a member of the class II PAKs family, which is a conserved family of serine/threonine kinases. Although the effects of PAK6 on many malignancies, especially in prostate cancer, have been studied for a long time, the role of PAK6 in mitochondria remains unknown. Methods: The expression of PAK6, SIRT4 and ANT2 in prostate cancer and adjacent non-tumor tissues was detected by immunohistochemistry. Immunofuorescence and immunoelectron microscopy were used to determine the subcellular localization of PAK6. Immunoprecipitation, immunofuorescence and ubiquitination assays were performed to determine how PAK6 regulates SIRT4, how SIRT4 regulates ANT2, and how PAK6 regulates ANT2. Flow cytometry detection and xenograft models were used to evaluate the impact of ANT2 mutant expression on the prostate cancer cell cycle and apoptosis regulation. Results: The present study revealed that the PAK6-SIRT4-ANT2 complex is involved in mitochondrial apoptosis in prostate cancer cells. It was found that PAK6 is mainly located in the mitochondrial inner membrane, in which PAK6 promotes SIRT4 ubiquitin-mediated proteolysis. Furthermore, SIRT4 deprives the ANT2 acetylation at K105 to promote its ubiquitination degradation. Hence, PAK6 adjusts the acetylation level of ANT2 through the PAK6-SIRT4-ANT2 pathway, in order to regulate the stability of ANT2. Meanwhile, PAK6 directly phosphorylates ANT2 atT107 to inhibit the apoptosis of prostate cancer cells. Therefore, the phosphorylation and deacetylation modifications of ANT2 are mutually regulated, leading to tumor growth in vivo. Consistently, these clinical prostate cancer tissue evaluations reveal that PAK6 is positively correlated with ANT2 expression, but negatively correlated with SIRT4. Conclusion: These present findings suggest the pivotal role of the PAK6-SIRT4-ANT2 complex in the apoptosis of prostate cancer. This complex could be a potential biomarker for the treatment and prognosis of prostate cancer.