Evaluation of the antitumoral effect of dihydrocucurbitacin-B in both in vitro and in vivo models

We evaluated both in vitro and in vivo antitumoral properties of an isolated compound from Wilbrandia ebracteata, dihydrocucurbitacin-B (DHCB), using B16F10 cells (murine melanoma). We made use of MTT and H-3-Thymidine assays to investigate the cell viability and cell proliferation, flow cytometry analysis to monitor cell cycle and apoptosis, western blot analysis to evaluate the expression of cell cycle proteins, imunofluorescence analysis and in vivo tumor growth and metastasis. Dihydrocucurbitacin-B significantly reduced cell proliferation without important effects on cells viability. DHCB lead cells to accumulate in G2/M phases accompanied by the appearance of polyploid cells, confirmed by fluorescence assays that demonstrated a remarkable alteration in the cell cytoskeleton and formation of binuclear cells. Annexin-V-FITC incorporation demonstrated that DHCB did not induce apoptosis. About 10 mu g/mL DHCB was found to decrease cyclin-A, and especially in cyclin-B1. The in vivo experiments showed that DHCB treatment (once a day up to 12 days; p.o.) was able to reduce the tumor growth and lung metastasis up to 83.5 and 50.3%, respectively. Dihydrocucurbitacin-B reduces cell proliferation due to a decrease in the expression of cyclins, mainly cyclin-B1 and disruption of the actin cytoskeleton, arresting B16F10 cells in G2/M phase. Taken together, the in vitro and in vivo experiments suggest that DHCB was effective against cancer, however, it remains to be proved if DHCB will be a good candidate for drug development.