Anti-angiogenic activity of triptolide in anaplastic thyroid carcinoma is mediated by targeting vascular endothelial and tumor cells Wenbo Zhu 1 , Songmin He 1 , Yan Li 1 , Pengxin Qiu, Minfeng Shu, Yanqiu Ou, Yuehan Zhou, Tiandong Leng, Jun Xie, Xiaoke Zheng, Dong Xu, Xingwen Su, Guangmei Yan ⁎ Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou 510080, China abstract article info Article history: Received 20 July 2009 Received in revised form 29 September 2009 Accepted 14 October 2009 Keywords: Triptolide Tumor angiogenesis Anaplastic thyroid carcinoma Vascular endothelial cells NF-κB VEGF Triptolide is confirmed to suppress angiogenesis of anaplastic thyroid carcinoma. Here we further expound the precise mechanism involved in this activity. Triptolide downregulated nuclear factor kappa B (NF-κB) pathway and its targeting genes associated with endothelial cell mobilization in human umbilical vein endothelial cells (HUVECs) and impaired VEGF expression in thyroid carcinoma TA-K cells. Furthermore, both triptolide and the conditioned medium from triptolide-treated TA-K cells (CMT) significantly attenuated proliferation, migration and tube formation of HUVECs. In vivo, triptolide inhibited TA-K cell- induced tumor growth, vascular formation and VEGF expression. Our data establish that triptolide inhibits tumor angiogenesis by the dual action on vascular endothelial cells and tumor cells, thus providing a novel and overall explanation for the anti-angiogenesis action of triptolide. The multicellular targets emphasize triptolide as a high-performance and potential angiogenesis inhibitor. © 2009 Elsevier Inc. All rights reserved. 1. Introduction Anaplastic thyroid carcinoma (ATC) is one of the most aggressive malignancies and also the most destructive one in all thyroid cancer types (Pasieka, 2003). This kind of undifferentiated solid tumor is endowed with angiogenic capability and their growth, invasion and metastasis are angiogenesis-dependent (Luboshitzky and Dharan, 2004; Mitchell and Parangi, 2005). Patients suffering from ATC usually seek treatment with an enlarging mass in their necks and die from neighbouring organ invasion. Despite modern treatments with surgical resection, radiotherapy and chemotherapy, few patients have survived beyond 12 months after diagnosis (Ain, 1998). In our previous study, we established that a small molecule triptolide is capable of suppressing ATC angiogenesis (Zhu et al., 2009), but the mechanism involved in this effect is under investigation. Pathological angiogenesis is a hallmark of cancer, and it is well known that tumor cannot grow beyond a critical size or metastasize to another organ without blood vessels (Carmeliet and Jain, 2000). Thus, agents that block angiogenesis are attractive therapeutic options for the growth, progression and metastasis of tumors (Ferrara and Kerbel, 2005). In tumor angiogenic cascade, endothelial cells (ECs) are the direct and absolutely necessary executor. They are recruited to proliferate, migrate, form tube-like structure and eventually form blood vessels (Ribatti, 2004). Importantly, these activities of ECs are triggered by specific pro-angiogenic factors including vascular endo- thelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and so on, among which VEGF is well established as a key inducer of EC mobilization (Coultas et al., 2005; Hicklin and Ellis, 2005). Therefore, ECs and VEGF constitute the direct and indirect candidate targets for therapeutic intervention against angiogenesis, respectively. Although there exist all kinds of angiogenic inhibitors targeting either ECs or angiogenic growth factor, one possessing both targets is still expected to provide a higher-performance therapeutic modality for tumors. Triptolide is a natural product originally purified from the Chinese herb Tripterygium wilfordii Hook.f (TWHf), and has been shown to be a well-tolerated small molecule in the treatment of rheumatoid arthritis (Gu et al., 1995). Additional evidence has also shown that triptolide exerts anti-neoplastic properties in various human cancer cells, and its anti-proliferative and pro-apoptotic activities have been frequently proposed for the mechanisms of action (Carter et al., 2006; Yang et al., 2003). In our previous works, its anti-angiogenic activity in the treatment of cancer has been identified for the first time (Zhu et al., 2009). To develop triptolide as an angiogenesis inhibitor better, the exploration on its cellular targets is required. Vascular Pharmacology 52 (2010) 46–54 Abbreviations: ATC, anaplastic thyroid carcinoma; ECs, endothelial cells; VEGF, vascular endothelial growth factor; HUVECs, human umbilical vein endothelial cells; NF-κB, nuclear factor kappa B; uPA, urokinase-type plasminogen activator; FBS, fetal bovine serum; CBP, CREB-binding protein; CMC, the conditioned media from TA-K cells grown for 24 h; CMT, the conditioned medium from TA-K cells treated with triptolide for 24 h. ⁎ Corresponding author. Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan Road II, Guangzhou 510089, China. Tel.: +86 20 87333258; fax: +86 20 87330578. E-mail address: ygm@mail.sysu.edu.cn (G. Yan). 1 These authors contributed equally to this paper. 1537-1891/$ – see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.vph.2009.10.006 Contents lists available at ScienceDirect Vascular Pharmacology journal homepage: www.elsevier.com/locate/vph