P06.12
Purpose: Osteosarcoma is the most common type of malignant bone tumor in children and adolescents. This cancer has a poor prognosis, is highly metastatic and resistance to current therapeutic approaches. In searching of innovative natural anti-cancer components different herbal extracts used in phytotherapy were screened. Therefore, cardiac glycosides and aglyca – cardenolides and bufadienolides – from Digitalis sp., Strophanthus sp, Drimia maritima Convallaria majalis and Bufo sp. were examined in accordance to their potential of inducing apoptosis in osteosarcoma cell line 143B-HOS.
Methods: 143B-HOS cells cultures were exposed to increasing concentrations of 20 cardiac glycosides and aglyca for 24 h. Morphological changes were examined by phase contrast microscopy. Cell proliferation ability was measured using cell counting method with the CASY Cell Counter®. Early cytotoxicity was examined using LDH-assay. Apoptosis induction was evaluated by annexin V-APC/PI double staining and flow cytometry. In addition, changes in the mitochondrial membrane potential were measured using JC-1, a lipophilic cationic fluorescent marker.
Results: After 24 h treatment of 143B-HOS with cardiac glycosides and aglyca morphological changes were observed. Inhibitory effects on proliferation were detected in a dose dependent manner. Early cytotoxicity after 4 h treatment was not significant. Both, cardiac glycoside and aglyca induced apoptosis in a dose- and time-dependent manner. Here, the bufadienolides Proscillarin A and Arenobufagin and the cardenolides Evomonosid, Convallatoxol and g-Strophanthin showed the strongest apoptosis induction, associated with a decrease of mitochondrial membrane potential. In contrast, the bufadienolide Bufaregonin showed the least potential. The bufadienolid Resibufogenin and the cardenolid Uzarin did not show any effect in apoptosis induction or mitochondrial membrane potential.
Conclusion: In conclusion cardiac glycosides induce higly effective apoptosis in osteosarcoma cell line 143B-HOS and decrease mitochondrial membrane potential. Both the cardenolides and bufadienolides – glycosides as well as aglyca – showed apoptosis induction. The bufadienolid Proscillaridin A possessed the strongest potential.
Contact: Catharina Delebinski, catharina.delebinski@charite.de
