Department of Urology, Geisinger Clinic, Danville, Pennsylvania, USA.
Prostate. 2010 Jun 15;70(9):971-81. doi: 10.1002/pros.21131.
Autophagy is a cellular process of degradation of macromolecules and organelles and activated under nutritional stress. Statins are a class of inhibitors of 3-hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase, a key enzyme in synthesis of cholesterol. Epidemiological studies have shown that statin use decreases the incidence of advanced prostate cancer. We explored the idea that treatment of atorvastatin, a commonly prescribed statin for treatment of hypercholesterolemia, induces autophagy in prostate cancer cells.
The atorvastatin-induced autophagic process in prostate cancer PC3 cells was determined by detection of cellular level of LC3-II, an autophagosomal marker, via immunoblotting and immunofluorescent staining.
Atorvastatin treatment of PC3 cells for 40 hrs increased expression of LC3-II by more than 10 fold in a dose-dependent manner. Treatment of the cells with pepstatin A and E64-d, the autophagic protease inhibitors, dramatically increased atorvastatin-dependent LC3-II expression level, suggesting that atorvastatin induces autophagic flux. In addition, atorvastatin treatment caused rapid death of PC3 cells. Atorvastatin-induced autophagy and rapid cell death were reversed by addition of geranylgeraniol, not farnesol, into culture medium, indicating that atorvastatin-mediated inhibition of geranylgeranyl biosynthesis causes autophagy and cell death. Furthermore, atorvastatin did not induce autophagy or cell death in normal prostate RWPE1 cells, and induced only a minor autophagic response in AR-positive prostate cancer LNCaP cells.
Our studies demonstrate that statins induce autophagy and autophagy-associated cell death in PC3 cells, likely through inhibition of geranylgeranylation, and suggest that autophagic response to statins may partially underlie the protective effects of statins on prostate cancer progression. Importantly, these findings highlight additional mechanisms by which statins might be used for prostate cancer therapy.
自噬是细胞降解大分子和细胞器的过程，在营养应激下被激活。他汀类药物是 3-羟基-3-甲基戊二酰辅酶 A（HMG-CoA）还原酶的抑制剂，该酶是胆固醇合成的关键酶。流行病学研究表明，他汀类药物的使用降低了晚期前列腺癌的发病率。我们探讨了阿托伐他汀（一种常用于治疗高胆固醇血症的他汀类药物）治疗是否会诱导前列腺癌细胞自噬的想法。
通过免疫印迹和免疫荧光染色检测细胞内 LC3-II（自噬体标记物）的水平来确定阿托伐他汀诱导的前列腺癌细胞自噬过程。
阿托伐他汀处理 PC3 细胞 40 小时后，LC3-II 的表达水平呈剂量依赖性增加超过 10 倍。用胃蛋白酶抑制剂 A 和 E64-d 处理细胞，这些自噬蛋白酶抑制剂，显著增加了阿托伐他汀依赖性 LC3-II 表达水平，表明阿托伐他汀诱导自噬流。此外，阿托伐他汀处理导致 PC3 细胞快速死亡。在培养基中加入香叶基香叶醇而不是法呢醇，可逆转阿托伐他汀诱导的自噬和快速细胞死亡，表明阿托伐他汀介导的香叶基生物合成抑制导致自噬和细胞死亡。此外，阿托伐他汀在正常前列腺 RWPE1 细胞中既不诱导自噬也不诱导细胞死亡，在 AR 阳性前列腺癌 LNCaP 细胞中仅诱导轻微的自噬反应。
我们的研究表明，他汀类药物通过抑制香叶基化诱导 PC3 细胞自噬和自噬相关的细胞死亡，并提示他汀类药物对前列腺癌进展的保护作用可能部分是通过自噬反应介导的。重要的是，这些发现强调了他汀类药物治疗前列腺癌的其他机制。
