Bufalin and cinobufagin may inhibit the proliferation of prostate cancer cell lines associated with sustained elevation of the [Ca(2+)](i) and that of apoptosis.

Prostate cancer has its highest incidence in the USA and is becoming a major concern in Asian countries. Bufadienolides are extracts of toxic glands from toads and are used as anticancer agents, mainly on leukemia cells. In the present study, the antiproliferative and apoptotic mechanisms of bufalin and cinobufagin on prostate cancer cells were investigated. Proliferation of LNCaP, DU145, and PC3 cells was measured by 3-(4,5-dimethylthiazol-2-yle)-2,5-diphenyltetrazolium bromide assay and the doubling time (tD) was calculated. Bufalin and cinobufagin caused changes in the tD of three prostate cancer cell lines, which were more significant than that of human mesangial cells. In addition, bufadienolides induced prostate cancer cell apoptosis more significantly than that in breast epithelial cell lines. After treatment, the caspase-3 activity and protein expression of caspase-3, -8, and -9 were elevated. The expression of other apoptotic modulators, including mitochondrial Bax and cytosolic cytochrome c, were also increased. However, expression of p53 was only enhanced in LNCaP P rostate cancer is currently showing its highest incidence for decades, and is the second-leading cause of cancer death among men in the USA.(1) It has been estimated that 186 320 new cases of prostate cancer will be diagnosed and that 28 660 deaths attributed to prostate cancer will occur in the USA in 2008.(2) In addition, the mortality of prostate cancer has also increased in Asian countries during the past decade. An assay for prostate-specific antigen has raised the early detection level of prostate cancer, which is curable by surgical and radiation therapies. Androgen ablation is the most common treatment for metastatic prostate cancer; however, 20-30% patients with prostate cancer experience recurrent disease.(3,4) Therefore, searching for chemoprevention or chemical controls for prostate cancer has become a crucial concern.Bufalin and cinobufagin, the major digoxin-like components of Chan-Su extracts from the venom of Bufo bufo gargarizan, have been reported as Na + -K + -ATPase inhibitors that result in elevation of the intracellular calcium concentration. (5,6) On the basis of this mechanism, bufalin and cinobufagin increase vasoconstriction, and have long been used as a treatment for heart failure by Chinese medicine in Asian countries. Disruption of intracellular calcium homeostasis induces apoptosis in diverse cell types.(7) Our previous results have illustrated that bufalin and cinobufagin are able to induce elevated calcium concentration and cell apoptosis in prostate cancer cells, but the detailed mechanism of this remains unclear.(8) Bufalin is also known as a topoisomerase II inhibitor. Topoisomerase II is a nuclear enzyme that relaxes supercoiled DNA at the time of DNA replication. Its inhibitors result in protein-linked DNA double-strand breaks. (9) Some of the topoisomerase poisons, such as etoposide and adriamycin, are efficient and widely prescribed anticancer drugs. (10) According to the mechanism described above, bu...

Prostate carcinoma is one of the most common malignant tumors and has become a more common cancer in men. Previous studies demonstrated that evodiamine (EVO) exhibited anti-tumor activities on several cancers, but its effects on androgen-independent prostate cancer are unclear. In the present study, the action mechanisms of EVO on the growth of androgen-independent prostate cancer cells (DU145 and PC3 cells) were explored. EVO dramatically inhibited the growth and elevated cytotoxicity of DU145 and PC3 cells. The flow cytometric analysis of EVO-treated cells indicated a block of G2/M phase and an elevated level of DNA fragmentation. The G2/M arrest was accompanied by elevated Cdc2 kinase activity, an increase in expression of cyclin B1 and phosphorylated Cdc2 (Thr 161), and a decrease in expression of phosphorylated Cdc2 (Tyr 15), Myt-1, and interphase Cdc25C. TUNEL examination showed that EVO-induced apoptosis was observed at 72 h. EVO elevated the activities of caspase 3, 8, and 9 in DU145 cells, while in PC3 cells only the activities of caspase 3 and 9 were elevated. EVO also triggered the processing of caspase 3 and 9 in both DU145 and PC3 cells. We demonstrate that roscovitine treatment result in the reversion of G2/M arrest in response to EVO in both DU145 and PC3. However, inhibitory effect of roscovitine on EVO-induced apoptosis could only be observed in DU145 rather than PC3. In DU145, G2/M arrest might be a signal for initiation of EVO-triggered apoptosis. Whereas EVO-triggered PC3 apoptosis might be independent of G2/M arrest. These results suggested that EVO inhibited the growth of prostate cancer cell lines, DU145 and PC3, through an accumulation at G2/M phase and an induction of apoptosis.

Key words: prostate cancer; evodiamine; cell growth; G2/M arrest; apoptosisProstate cancer is the most commonly diagnosed malignancy in American men over 40 years of age and is the second leading of cancer deaths. 1,2 Recently, prostate cancer has become more and more common in Asia including Taiwan. 3 According to previous studies, widely accepted risk factors for prostate cancer are age, race, ethnicity, dietary habits, androgen production and metabolism. 4 Prostate cancer is characterized by an initial androgen dependency in which the growth of cancer is enhanced by androgen. 5 In this stage, treatment is aimed at either lowering the plasma level of testosterone or inhibiting its biological effects or those of its metabolites at the target tissue levels. Orchidectomy, LHRH agonists and antiandrogenic drugs have been used clinically for treatment of androgen-dependent prostate cancer. 6 -8 However, these therapies cause psychological and physiological side effects. 9 -11 The drugs for androgen-dependent prostate cancer have merits and limitations. Because of the side effects and limitations of the currently available treatments, there is a need to identify and develop new antitumor agents against androgen-dependent prostate cancer.It has been demonstrated that several microchemicals that are isolated from herbs and plants with diversified pharmacological properties exert inhibitory effects on the proliferation of cancer. [12][13][14][15][16] The microchemicals could be the most desirable agents for prevention or intervention of human cancer incidence and mortality due to stomach, colon, breast, esophagus, lung, bladder and even prostate carcinoma. [17][18][19] Our previous studies showed that cardiac glycosides from digitalis and Chansu exhibited the antiproliferative effects on prostate cancer cells including DU145, PC3 and LNCaP to mediate the elevated [Ca2 ϩ ] i and apoptosis. 19,20 Wu-Chu-Yu is a long-standing Chinese herb used for syndromes characterized by cold hands and gastrointestinal disorders. Evodiamine is one of the major bioactive compounds isolated and purified from Wu-Chu-Yu. It has been demonstrated that evodiamine influences many physiological functions including vasotension, anoxia and body temperature. [21][22][23] Meanwhile, evodiamine exhibits an anti-inflammatory effect on change of nitric oxide production in murine macrophage. 24 Recently, we found that evodiamine inhibited testosterone production via a decrease of 17␤-hydroxysteroid dehydrogenase activity in testicular interstitial cells. 25 Interestingly, the evidence showed that rutaecarpine, the other bioactive compound isolated from Wu-Chu-Yu, inhibited the growth of many kinds of cancers including breast, lung and kidney cancers. 26 Furthermore, Okasawara et al. 27,28 reported that evodiamine inhibited the cell proliferation, cell migration and lung metastasis of murine colon cancer cells.According to previous reports, evodiamine has been recognized as a compound for anti-metastatic and anti-tumor agent in colon cancer cells. It w...

The incidence of thyroid cancer increases with age, and it is twice in women as common as in men. The undifferentiated thyroid cancer (UTC) is the most aggressive of all thyroid cancers. Unfortunately, there are almost no efficacious therapeutic modalities. It is important to develop some new effective therapies. Evodiamine is a chemical extracted from a kind of Chinese herb named Wu-Chu-Yu and has been demonstrated to be effective in preventing the growth of a variety of cancer cells. In the present study, the mechanism by which evodiamine inhibited the undifferentiated thyroid cancer cell line ARO was examined. Based on 3-(4,5-dimethylthiazol -2-yle)2,5-diphenyltetrazolium bromide (MTT) assay, cell proliferation rate was reduced dose-dependently by evodiamine, but not by rutaecarpine. According to the flow cytometric analysis, evodiamine treatment resulted in G2/M arrest and DNA fragmentation in ARO cells. The G2/M arrest was accompanied with an increase of the expression of cdc25C, cyclin B1, and cdc2-p161 protein, and it was also with a decrease of the expression of cdc2-p15. Furthermore, by using the TUNEL assay, evodiamine-induced apoptosis was observed at 48 h and extended to 72 h. Western blotting demonstrated that evodiamine treatment induced the activation of caspase-8, caspase-9, caspase-3, and the cleavage of poly ADP-ribose polymerase (PARP). These results suggested that evodiamine inhibited the growth of the ARO cells, arrested them at M phase, and induced apoptosis through caspases signaling.