Yang Li-Jyun, Jeng Chung-Jiuan, Kung Hsiu-Ni, Chang Cheng-Chi, Wang An-Guor, Chau Gar-Yang, Don Ming-Jaw, Chau Yat-Pang
Institute of Anatomy and Cell Biology, School of Medicine, National Yang-Ming University, 155 Li-Nung Street, Sec. 2, Shih-pai,Taipei, 112, Taiwan.
J Biomed Sci. 2005;12(2):347-61. doi: 10.1007/s11373-005-0973-z.
Tanshinone IIA, a major component extracted from the traditional herbal medicine, Salvia miltiorrhiza Bunge, is known to exhibit potent cytotoxicity against various human carcinoma cells in vitro. However, the mechanism by which tanshinone IIA produces this anti-tumor effect remains unknown. Since anti-neovascularization has generally been regarded as an effective strategy for anti-cancer therapy, we decided to investigate the mechanism underlying tanshinone IIA-mediated death of human endothelial cells. In this study, we demonstrate that tanshinone IIA elicits human endothelial cell death independent of oxidative stress. These events are partially calcium-dependent and actually dependent upon NAD(P)H: quinone oxidoreductase (NQO1) activity. Tanshinone IIA induces an increase in intracellular calcium, which triggers the release of cytochrome c, thus causing loss of the mitochondrial membrane potential (MMP), resulting in the subsequent activation of caspases. Blocking the induction of Ca2+ perturbation with BAPTA-AM partially rescued cells from tanshinone IIA-induced cytotoxicity. Additionally, blocking NQO1 activity with dicoumoral or inhibiting caspase activities with the general caspase inhibitor, z-VAD-fmk, prevented cell death induced by tanshinone IIA. Therefore, our results imply that tanshinone IIA-mediated cytotoxicity against human endothelial cells may occur through activation of NQO1, which induces a calcium imbalance and mitochondrial dysfunction, thus stimulating caspase activity.
丹参酮IIA是从传统草药丹参中提取的主要成分，已知其在体外对多种人类癌细胞具有强大的细胞毒性。然而，丹参酮IIA产生这种抗肿瘤作用的机制尚不清楚。由于抗血管生成通常被视为一种有效的抗癌治疗策略，我们决定研究丹参酮IIA介导的人类内皮细胞死亡的潜在机制。在本研究中，我们证明丹参酮IIA可引发人类内皮细胞死亡，且与氧化应激无关。这些事件部分依赖于钙，实际上依赖于NAD(P)H：醌氧化还原酶（NQO1）的活性。丹参酮IIA诱导细胞内钙增加，进而触发细胞色素c的释放，从而导致线粒体膜电位（MMP）丧失，随后激活半胱天冬酶。用BAPTA-AM阻断Ca2+扰动的诱导可部分挽救细胞免受丹参酮IIA诱导的细胞毒性。此外，用双香豆素阻断NQO1活性或用通用半胱天冬酶抑制剂z-VAD-fmk抑制半胱天冬酶活性可防止丹参酮IIA诱导的细胞死亡。因此，我们的结果表明，丹参酮IIA介导的对人类内皮细胞的细胞毒性可能通过激活NQO1而发生，NQO1诱导钙失衡和线粒体功能障碍，从而刺激半胱天冬酶活性。
