## 4 Anti-Cancer Activities of Tanshinones
### Inhibition of Adhesion, Migration, Invasion and Metastasis  
Cancer metastasis is a complex process through coordination between cancer cells and surrounding microenvironment, including breaking through the basement membrane barriers, intravasation into vessel, survival in the circulation, extravasation from vessels, and survival and proliferation in the target tissues. Adhesion, migration and invasion are indispensable steps for cancer metastasis, therefore are important pharmacological targets of novel anti-cancer agents.  
In 1999, [PERSON] _et al._[228] investigated the effect of several natural products including TIIA on the expression of membrane cluster differentiation (CD) antigens of human PGCL3 pulmonary giant cell carcinoma cells. They found that CD42a and CD63 might promote but CD9 might inhibit PGCL3 cell invasion through Matrigel. TIIA treatment (9, 34 and 68 \(\upmu\)M) decreased CD42a and CD63 expression but increased CD9, indicating a possible inhibition of TIIA on the invasion capability of PGCL3 cells [228]. Later, [PERSON] _et al._[229] found that TIIA at 10-50 \(\upmu\)M inhibited leukemia NB4 cell adhesion to extracellular matrix (ECM) component (laminin, fibronectin, collagen and vitronectin)-coated surfaces and invasion through Matrigel in a concentration-dependently manner. [PERSON] _et al._[230] reported that TIIA at low \(\upmu\)M concentrations (3.4-6.8 \(\upmu\)M) inhibited migration and invasion of human HT29 and SW480 colon cancer cells in a concentration- and time-dependent manner. TIIA decreased urokinase plasminogen activator (uPA), matrix metalloproteinase (MMP)-2 and MMP-9, increased tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2, and suppressed nuclear accumulation of NF-kB P65, a crucial subunit of nuclear factor-kappaB (NF-kB) pathway. TIIA also inhibited liver metastasis of colon cancer in a mouse tail vein metastasis model. After 5 weeks of TIIA treatment (20 and 80 mg/kg, daily intragastric administration), the liver metastasis rate of SW480 colon cancer cells was decreased by 40% and 61%, respectively [230]. A similar concentration range of TIIA also inhibited _in vitro_ migration and invasion and _in vivo_ metastasis rate of human HepG2 and SMMC-7721 liver cancer cells in a concentration- and time-dependent manner, in association with inhibition of NF-kB pathway as well as MMP-2 and MMP-9 expression and activity [231]. TIIA-induced inhibition of MMP expression and activity was also observed in other cancer cells such as osteosarcoma and stomach tumor [170,232].  
[PERSON] _et al._[110] reported that TI suppressed MDA-MB-231 breast cancer cell metastasis involving modulating surface adhesion molecules. TI at 5-50 \(\upmu\)M completely inhibited the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in TNF-\(a\)-stimulated HUVECs, as well as the adhesion of MDA-MB-231 cells to HUVECs and migration of MDA-MB-231 cells through extracellular matrix. Knockdown of ICAM-1 and VCAM-1 by siRNA mimicked TI-induced inhibition of MDA-MB-231 cell adhesion to HUVECs. Moreover, _in vivo_ administration of TI (10 mg/kg, daily _i.p._ injection for 4 weeks) reduced lung metastasis of MDA-MB-231 xenograft tumors in nude mice [110]. Similarly, [PERSON] _et al._[233] reported that TI inhibited migration, invasion and MMPs activity in macrophage conditional medium-stimulated CL1-5 lung cancer cells _in vitro_, and reduced the tumorigenesis and metastasis of CL1-5 lung cancer xenografts in severe combined immunodeficient (SCID) mice, in association with reduction of interleukin-8 (IL-8, an angiogenesis factor promoting angiogenesis and metastasis). Mechanically, the inhibition of IL-8 induced by TIIA likely happened at the transcription level via interfering with the binding of transcriptional factors AP-1 and NF-kB to the IL-8 promoter [233].