Kim Won, Yoon Jung-Hwan, Kim Jung-Ryul, Jang In-Jin, Bang Yung-Jue, Kim Yoon-Jun, Lee Hyo-Suk
Department of Internal Medicine, Seoul National University Boramae Hospital, Seoul, South Korea.
Cancer Chemother Pharmacol. 2009 Aug;64(3):497-507. doi: 10.1007/s00280-008-0897-1. Epub 2008 Dec 20.
Hepatocellular carcinoma (HCC) is characterized by hypervascularity and chemoresistance. Protein kinase C (PKC) participates in cancer progression by enhancing anti-apoptotic signals, angiogenesis, and chemoresistance. Statins have a selective anti-cancer effect due to over-expression of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoAR) in cancer cells, but statins may also activate PKC. Thus, we hypothesized that simultaneous treatment with statin and PKC inhibitor might synergistically enhance their anti-tumor efficacies against HCCs.
Hepatocellular carcinoma cell growth was assessed using MTS assays, apoptotic cell death by DAPI staining, and apoptotic signaling cascades were explored by immunoblotting. An in vivo model of HCC was established in C3H mice intradermally implanted with MH134 cells. Lovastatin and/or a PKC inhibitor (enzastaurin) was subsequently administered. Anti-tumor efficacies were evaluated by measuring tumor volumes and quantifying apoptotic cells and microvessel densities (MVD).
Co-treatment with lovastatin and enzastaurin was found to synergistically suppress HCC cell growth in vitro. Lovastatin induced HCC cellular apoptosis by activating mitochondrial apoptotic signals, and although enzastaurin alone did not induce apoptosis, its addition significantly enhanced lovastatin-induced apoptosis. This enhanced apoptosis was attributed to increased caspase-9 activation in these cells. Moreover, tumor growth was significantly suppressed in mice co-treated with lovastatin and enzastaurin, and percentages of TUNEL-positive cells were significantly increased and MVDs were significantly decreased in those mice.
Combinatorial treatment with statin and PKC inhibitor was found to enhance anti-tumor efficacy in vivo and in vitro. Further studies are warranted to prove anti-tumor efficacy of this potential therapy in human HCCs.
肝细胞癌（HCC）的特征是血管增生和化疗耐药。蛋白激酶C（PKC）通过增强抗凋亡信号、血管生成和化疗耐药参与癌症进展。由于癌细胞中3-羟基-3-甲基戊二酰辅酶A还原酶（HMG-CoAR）的过度表达，他汀类药物具有选择性抗癌作用，但他汀类药物也可能激活PKC。因此，我们假设他汀类药物和PKC抑制剂联合治疗可能会协同增强它们对HCC的抗肿瘤疗效。
使用MTS分析评估肝癌细胞生长，通过DAPI染色评估凋亡细胞死亡，并通过免疫印迹探索凋亡信号级联反应。在皮内植入MH134细胞的C3H小鼠中建立HCC体内模型。随后给予洛伐他汀和/或PKC抑制剂（恩扎妥林）。通过测量肿瘤体积以及量化凋亡细胞和微血管密度（MVD）来评估抗肿瘤疗效。
发现洛伐他汀和恩扎妥林联合治疗在体外可协同抑制HCC细胞生长。洛伐他汀通过激活线粒体凋亡信号诱导HCC细胞凋亡，虽然单独使用恩扎妥林不会诱导凋亡，但加入恩扎妥林可显著增强洛伐他汀诱导的凋亡。这种增强的凋亡归因于这些细胞中caspase-9激活增加。此外，在联合使用洛伐他汀和恩扎妥林治疗的小鼠中，肿瘤生长受到显著抑制，这些小鼠中TUNEL阳性细胞百分比显著增加，MVD显著降低。
发现他汀类药物和PKC抑制剂联合治疗可增强体内和体外的抗肿瘤疗效。有必要进一步研究以证明这种潜在疗法对人类HCC的抗肿瘤疗效。
