Tanshinone IIA Induces Mitochondria Dependent Apoptosis in Prostate Cancer Cells in Association with an Inhibition of Phosphoinositide 3-Kinase/AKT Pathway

Abstract

Apoptosis, also called programmed cell death, is morphologically characterized by cell shrinkage, membrane remodeling, cell blebbing, chromatin condensation and DNA fragmentation with apoptotic bodies.1-3) Apoptosis activation has been considered a good target in cancer therapies. 4,5) In general, apoptosis is regulated by pro-apoptotic and antiapoptotic proteins of the Bcl-2 family and executed through caspases (or cysteine-aspartic proteases), chiefly via two major and inter-related pathways, i.e., the mitochondria-dependent "intrinsic" cytochrome c/caspase-9 pathway and the death receptor-mediated "extrinsic" caspase-8 pathway. [6][7][8] Additionally, apoptosis is controlled by various cell signaling pathways such as the phosphoinositide 3-kinase (PI3K)/AKT survival pathway, regulating apoptosis chiefly by blocking caspase-9 and the mitochondria damaging Bcl-2 family protein, Bad, through phosphorylative inactivation. 9)Tanshinone IIA (Tan IIA,14,6,8,13, Fig. 1A), one of the phytochemical compounds isolated from the Chinese medicinal herb Danshen (root of Salvia miltiorrhiza BUNGE), has been reported to exert diverse biological properties including anti-oxidative, 3,10,11) anti-angiogenic, 12) and anti-inflammatory activities.13) More importantly, anti-cancer activities have been reported including human hepatoma, [14][15][16][17] breast cancer 18) and leukemia. 19) However, there is no report of anticancer activity of Tan IIA on prostate cancer cells. Thus, in the present study, we investigated the cytocidal/apoptosis effect against prostate cancer cell lines of different pathogenetic make-up: LNCaP (p53 null, phosphate and tensin homolog (PTEN) null-high AKT, androgen sensitive) and PC-3 (p53 null, PTEN null-high AKT, androgen receptor null). Our mechanistic investigations suggested an involvement of mitochondria-intrinsic caspase activation cascade and inhibition of PI3K/AKT pathway. MATERIALS AND METHODSTanshinone IIA Isolation The procedure of Tan IIA (Fig. 1A) isolation is as reported by Choi and colleagues. 20)Cell Culture Human prostate cancer cells LNCaP (ATCC CRL 1740, p53 wild type, PTEN mutant-high AKT) and PC3 (ATCC CRL 1435, p53 null, PTEN null-high AKT), and breast cancer cells MDA-MB-231 (ATCC HTB 26, p53 mutant, wild type PTEN-low AKT) were obtained from American Type Culture Collection (ATCC) and maintained in RPMI 1640 supplemented with 10% fetal bovine serum (FBS) and 2 mmol/l L-glutamine, 10 mmol/l N-(2-hydroxyethyl)piperazine-NЈ-2-ethanesulfonic acid (HEPES), 1 mmol/l sodium pyruvate, and 4.5% D-glucose without antibiotics.Cytotoxicity Assay The cytotoxicity of Tan IIA was assessed by a tetrazolium salt, 2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) assay. LNCaP or PC3 cells were seeded onto 96-well microplates at a density of 1ϫ10 4 cells per well in 100 ml of complete medium. After incubation for 24 h, cells were exposed to var- IIA; 14,16-epoxy-20-nor-5(10),6,8,13,15-abietapentaene-11,12-dione), a phytochemical derived from the roots of Salvia miltio...

Tanshinone IIA attenuates the cerebral ischemic injury-induced increase in levels of GFAP and of caspases-3 and -8

“…The results presented here show that TSA inhibited ischemia-induced cell death in the entorhinal cortex. This finding parallels that of a study using prostatic cancer cells, where TSA also had an anti-apoptic effect (Won et al, 2010). Since many neurodegenerative diseases involve cell death and inappropriately elevated levels of immune activity, it is likely that an agent such as TSA with anti-inflammatory and anti-apoptic properties, will also find application in the treatment of a broader range of age-related diseases of the nervous system.…”

Tanshinone IIA inhibits the growth of pancreatic cancer BxPC-3 cells by decreasing protein expression of TCTP, MCL-1 and Bcl-xL

“…In addition, the anti-apoptotic mechanism of TCTP has also been associated with antagonization of Bax (21). Tan-IIA also downregulates expression of the mitochondrial protective Bcl-2 family memeber MCL-1, inducing apoptosis in prostate cancer cells (22). These observations indicate that Tan-IIA inhibits protein expression of TCTP, MCL-1 and Bcl-xl to destroy mitochondrial function and increase Bax and Caspase-3 expression, inducing apoptosis in human pancreatic …”

In vitro inhibition of invasion and metastasis in colon cancer cells by TanIIA

“…The cardiovascular pharmacological effects of TanIIA include preventing atherosclerosis, shortening the myocardial infarction area, reducing myocardial oxygen consumption, and inhibiting thrombosis formation and platelet aggregation (Xu et al, 2006). Data indicate that Tan has better clinical prospects as an anti-tumor drug, as previous studies have shown that TanIIA can induce apoptosis in cervical cancer cells, HL-60 cells, and K562 cells, although its mechanism of action requires further study (Sung et al, 1999;Wang et al, 2003;Shan et al, 2009;Won et al, 2010;Chiu and Su, 2010;Yun et al, 2013).…”