Cancer and Cell Death Laboratory, Department of Life Science, National Institute of Technology, Rourkela, 769008, Odisha, India.
Khallikote University, Berhampur, Ganjam, 761008, Odisha, India.
Life Sci. 2021 Jan 1;264:118722. doi: 10.1016/j.lfs.2020.118722. Epub 2020 Nov 5.
Secretory clusterin (sCLU) plays an important role in tumor development and cancer progression. However, the molecular mechanisms and physiological functions of sCLU in oral cancer is unclear. We examined the impact of sCLU-mediated autophagy in cell survival and apoptosis inhibition in oral cancer.
Immunohistochemical analysis was performed to analyze protein expression in patient samples. Autophagy and mitophagy was studied by immunofluorescence microscopy and Western blot. The gain and loss of function was studied by overexpression of plasmid and siRNA approaches respectively. Cellular protection against nutrient starvation and therapeutic stress by sCLU was studied by cell viability, caspase assay and meta-analysis.
The data from oral cancer patients showed that the expression levels of sCLU, ATG14, ULK1, and PARKIN increased in grade-wise manners. Interestingly, sCLU overexpression promoted autophagy through AMPK/Akt/mTOR signaling pathway leading to cell survival and protection from long exposure serum starvation induced-apoptosis. Additionally, sCLU was demonstrated to interact with ULK1 and inhibition of ULK1 activity by SBI206965 was found to abolish sCLU-induced autophagy indicating critical role of ULK1 in induction of autophagy. Furthermore, sCLU was observed to promote expression of mitophagy-associated proteins in serum starvation conditions to protect cells from nutrient deprivation. The meta-analysis elucidated that high CLU expression is associated with therapy resistance in cancer and we demonstrated that sCLU-mediated mitophagy was revealed to inhibit cell death by cisplatin.
The present investigation has highlighted the probable implications of the clusterin-induced autophagy in cell survival and inhibition of apoptosis in oral cancer.
分泌型簇集素（sCLU）在肿瘤发生和癌症进展中发挥重要作用。然而，sCLU 在口腔癌中的分子机制和生理功能尚不清楚。我们研究了 sCLU 介导的自噬对口腔癌细胞存活和凋亡抑制的影响。
通过免疫组织化学分析分析患者样本中的蛋白表达。通过免疫荧光显微镜和 Western blot 研究自噬和线粒体自噬。通过过表达质粒和 siRNA 方法分别研究功能获得和功能丧失。通过细胞活力、半胱天冬酶测定和荟萃分析研究 sCLU 对营养饥饿和治疗应激的细胞保护作用。
来自口腔癌患者的数据表明，sCLU、ATG14、ULK1 和 PARKIN 的表达水平呈等级式增加。有趣的是，sCLU 过表达通过 AMPK/Akt/mTOR 信号通路促进自噬，导致细胞存活，并防止长时间暴露于血清饥饿诱导的凋亡。此外，sCLU 被证明与 ULK1 相互作用，并且通过 SBI206965 抑制 ULK1 活性发现可消除 sCLU 诱导的自噬，表明 ULK1 在诱导自噬中起关键作用。此外，在血清饥饿条件下观察到 sCLU 促进线粒体自噬相关蛋白的表达，以保护细胞免受营养剥夺。荟萃分析阐明了 CLU 高表达与癌症的治疗耐药性有关，我们证明了 sCLU 介导的线粒体自噬可抑制顺铂诱导的细胞死亡。
本研究强调了簇集素诱导的自噬在口腔癌细胞存活和凋亡抑制中的可能意义。
