Jiang Xianhan, Huang Yiqiao, Liang Xue, Jiang Funeng, He Yongzhong, Li Tian, Xu Guibin, Zhao Haibo, Yang Weiqing, Jiang Ganggang, Su Zhengming, Jiang Lingke, Liu Leyuan
Department of Urology, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
Department of Urology, Guangdong Key Laboratory of Clinical Molecular Medicine and Diagnostics, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, China.
Prostate. 2018 May;78(6):426-434. doi: 10.1002/pros.23487. Epub 2018 Jan 31.
P62 (also named sequestosome-1, SQSTM1) is involved in autophagy regulation through multiple pathways. It interacts with autophagosomes-associated LC3-II and ubiquitinated protein aggregates to engulf the aggregates in autophagosomes, interacts with HDAC6 to inhibit its deacetylase activity to maintain the levels of acetylated α-tubulin and stabilities of microtubules to enhance autophagosome trafficking, and regulates autophagy initiation and cell survival. We performed immunohistochemistry staining of P62 in prostate tissues from prostate cancer patients and found that levels of P62 in patients with prostate adenocarcinomas (PCA) are significantly higher than those in patients with benign prostate hyperplasia (BPH). High levels of P62 predict high tumor grade and high intensity of metastasis.
We created prostate cancer cell lines stably overexpressing P62 and then suppress the expression of P62 in the cell line stably overexpressing P62 with CRISPR technology. Cell proliferation assay with crystal violet, cell migration assay, cell invasion assay, Western blot analysis, and confocal fluorescent microscopy were conducted to test the impact of altered levels of P62 on the growth, migration, invasion, epithelial-to-mesenchymal transition, autophagy flux, HDAC6 activity, and microtubular acetylation of cancer cells.
P62 increased the levels of HDAC6 and reduced the acetylation of α-tubulin and the stability of microtubules. Consequently, high levels of P62 caused a promotion of epithelial-to-mesenchymal transition in addition to an impairment of autophagy flux, and further led to an enhancement of proliferation, migration, and invasion of prostate cancer cells.
P62 promotes metastasis of PCA by sustaining the level of HDAC6 to inhibit autophagy and promote epithelial-to-mesenchymal transition.
P62（也称为聚集体蛋白-1，SQSTM1）通过多种途径参与自噬调节。它与自噬体相关的LC3-II和泛素化蛋白聚集体相互作用，将聚集体吞噬到自噬体中，与HDAC6相互作用以抑制其去乙酰化酶活性，从而维持乙酰化α-微管蛋白的水平和微管的稳定性，增强自噬体运输，并调节自噬起始和细胞存活。我们对前列腺癌患者的前列腺组织进行了P62免疫组织化学染色，发现前列腺腺癌（PCA）患者的P62水平显著高于良性前列腺增生（BPH）患者。高水平的P62预示着高肿瘤分级和高转移强度。
我们构建了稳定过表达P62的前列腺癌细胞系，然后用CRISPR技术抑制该稳定过表达P62的细胞系中P62的表达。进行结晶紫细胞增殖试验、细胞迁移试验、细胞侵袭试验、蛋白质免疫印迹分析和共聚焦荧光显微镜检查，以测试P62水平改变对癌细胞生长、迁移、侵袭、上皮-间质转化、自噬通量、HDAC6活性和微管乙酰化的影响。
P62增加了HDAC6的水平，降低了α-微管蛋白的乙酰化和微管的稳定性。因此，高水平的P62除了损害自噬通量外，还促进了上皮-间质转化，并进一步导致前列腺癌细胞增殖、迁移和侵袭增强。
P62通过维持HDAC6水平来促进PCA转移，抑制自噬并促进上皮-间质转化。
