Tanshinone IIA Inhibits Angiogenesis through Down Regulation of COX-2 in Human Colorectal Cancer

Colorectal carcinoma (CRC) is the third most common and life-threatening malignant tumors in the world and has been rising over the years (Jemal et al., 2011). As one of the six hallmarks of carcinogenesis, micro-angiogenesis of tumor plays a significant role in carcinogenesis, development, invasion, as well as metastasis of the tumor (Arentz et al., 2011). Cyclooxygenase-2 (COX-2) is involved with multiple aspects of tumorigenesis of CRC. Detection of COX-2 activity in tumor tissue or tumor cell can be used as an important method to monitor carcinogenesis and development of CRC; moreover, the expression of intracellular COX-2 level can serve as a significant marker for anti-tumor drug screening. Tanshinone II-A (Tan II-A) is an effective constituent of Salvia Miltiorhizza – a traditional Chinese herb. Tan II-A is originally used for cardiovascular diseases, and recent studies have revealed a marked anti-tumor effect; the mechanism of which involves inhibition of cell proliferation (Chen et al., 2012), promotion of cell apoptosis (Dai et al., 2012), induction of cell differentiation (Wang et al., 2007; Zhang et al., 2010),