cinobufagin and Prostatic-Neoplasms

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 cells. Downregulation of p53 by antisense TP53 restored the cell viability suppressed by bufalienolides. Furthermore, the increased expression of Fas was more significant in DU145 and PC3 cells with mutant p53 than in LNCaP cells. Transfection of Fas small interfering RNA restored cell viability in the bufadienolide-treated cells. These results suggest that bufalin and cinobufagin suppress cell proliferation and cause apoptosis in prostate cancer cells via a sequence of apoptotic modulators, including Bax, cytochrome c, and caspases. The upstream mediators might be p53 and Fas in androgen-dependent LNCaP cells and Fas in androgen-independent DU145 and PC3 cells.

Topics: Androgens; Apoptosis; bcl-2-Associated X Protein; Bufanolides; Cell Proliferation; Cell Survival; Cytochromes c; Dose-Response Relationship, Drug; fas Receptor; Fluorescent Antibody Technique, Indirect; Formazans; Gene Expression Regulation, Neoplastic; Humans; Male; Prostatic Neoplasms; RNA, Messenger; Signal Transduction; Tetrazolium Salts; Tumor Suppressor Protein p53

Cardiac glycosides may induce oncolytic effects in cancers. This study was to evaluate bufalin and cinobufagin effects on the proliferation of prostate cancer cell lines named LNCaP, DU145, and PC3.. Cell proliferation was measured by MTT assay. The cytotoxic effects were determined by lactate dehydrogenase measurements. The intracellular calcium concentration ([Ca(2+)](i)) was measured by a dual-wavelength spectrometer system. TUNEL assay and flow cytometry were performed to measure percentage of apoptotic cells. A colorimetric assay was to measure caspases activities.. Bufalin and cinobufagin inhibited proliferation of cancer cells at doses of 0.1, 1, or 10 microM after 2-4 days of culture. Cytotoxicity of bufalin and cinobufagin on the DU145 and LNCaP cells was dose-dependent. Bufalin or cinobufagin increased [Ca(2+)](i) and apoptosis in cancer cells after a 24-hr culture as well as caspase 3 activities in DU145 and PC3 cells and caspase 9 activities in LNCaP cells.. 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.

Topics: Antineoplastic Agents; Apoptosis; Bufanolides; Calcium; Cell Division; Dose-Response Relationship, Drug; Humans; Intracellular Fluid; Male; Materia Medica; Prostatic Neoplasms; Sodium-Potassium-Exchanging ATPase; Tumor Cells, Cultured