Department of Pharmaceutical Sciences, Nesbitt School of Pharmacy, Wilkes University, Wilkes-Barre, PA, U.S.A.
Anticancer Res. 2021 Mar;41(3):1197-1202. doi: 10.21873/anticanres.14876.
BACKGROUND/AIM: Previous studies have shown that the sandalwood oil constituent α-santalol inhibits growth of cultured human prostate cancer cells in vitro and PC-3 prostate cancer xenografts. Along with the studies from our laboratory, it is well established that α-santalol targets the phosphatidylinositol-4,5-bisphosphate 3-kinase-AKT serine/ threonine kinase 1 (AKT) pathway to induce apoptosis but its growth-suppressive effects have not been fully elucidated. The current study was undertaken to investigate the role of autophagy in α-santalol-induced prostate cancer cell death.
Cell lines LNCaP and PC-3 were maintained in an atmosphere of 95% air and 5% CO2 at 37°C. Trypan blue dye exclusion assay was employed to assess the effects of α-santalol with/without 3-methyl adenine on the cell viability of prostate cancer cells. Acidic vesicular organelles induced by α-santalol treatment were detected by staining with acridine orange. Immunofluorescence and immunoblotting were performed to analyze expression of proteins involved in the AKT-mammalian target of rapamycin (mTOR) pathway.
LNCaP and PC-3 cells upon treatment with α-santalol resulted in characteristic features analogous to autophagic response, including formation of acidic vesicular organelles, recruitment and cleavage of microtubule-associated protein 1 light chain 3 (LC3) to autophagosomes. Alpha-santalol treatment further suppressed phosphorylation of activated AKT and mTOR, which are critical regulators of autophagic response. In addition, pre-treatment of PC-3 cells with specific inhibitor of autophagy (3-methyladenine) and co-treatment with α-santalol attenuated the expression of LC3-II and phospho-AKT, and significantly reduced the cell viability.
The present study indicates that α-santalol induces autophagy by targeting the AKT-mTOR pathway in prostate cancer cells, which may serve as a protective mechanism.
背景/目的：先前的研究表明，檀香油成分α-檀香醇在体外抑制培养的人前列腺癌细胞和 PC-3 前列腺癌异种移植物的生长。结合我们实验室的研究，α-檀香醇靶向磷脂酰肌醇-4,5-二磷酸 3-激酶-AKT 丝氨酸/苏氨酸激酶 1（AKT）途径诱导细胞凋亡已得到充分证实，但它的生长抑制作用尚未完全阐明。本研究旨在探讨自噬在α-檀香醇诱导的前列腺癌细胞死亡中的作用。
LNCaP 和 PC-3 细胞系在 95%空气和 5%二氧化碳的气氛中于 37°C 下维持。采用台盼蓝排斥试验评估α-檀香醇与/或 3-甲基腺嘌呤对前列腺癌细胞活力的影响。用吖啶橙染色检测由α-檀香醇处理诱导的酸性囊泡细胞器。通过免疫荧光和免疫印迹分析参与 AKT-雷帕霉素（mTOR）途径的蛋白质的表达。
LNCaP 和 PC-3 细胞用α-檀香醇处理后，会产生类似于自噬反应的特征性特征，包括形成酸性囊泡细胞器、微管相关蛋白 1 轻链 3（LC3）向自噬体的募集和切割。α-檀香醇处理进一步抑制了激活 AKT 和 mTOR 的磷酸化，这是自噬反应的关键调节剂。此外，用特异性自噬抑制剂（3-甲基腺嘌呤）预处理 PC-3 细胞并与α-檀香醇共同处理，可减弱 LC3-II 和磷酸化 AKT 的表达，并显著降低细胞活力。
本研究表明，α-檀香醇通过靶向 AKT-mTOR 途径诱导前列腺癌细胞自噬，这可能是一种保护机制。
