Molecular and cellular effects of two groups of antiproliferative agents, natural
brassinosteroids (BRs) and their synthetic derivatives, were examined in different human cancer cell
lines and in primary endothelial cells in vitro. Natural and synthetic BRs caused growth inhibition, cell
cycle arrest and initiation of apoptosis in many different cancer cell lines. The inhibition of proliferation
and migration of human endothelial cells by BRs was demonstrated and evidences were obtained that
BRs initiate cell death by apoptosis. And, analogues of BRs were found to be more effective than
natural BRs. Observed inhibition of migration and tube formation demonstrated the antiangiogenic
activity of BRs. These findings indicate a potential use of BRs in the prevention of metastasis
development. Investigation of the mechanisms of action of BRs in human cancer and endothelial cells
using cellular and molecular techniques indicated the possible involvement of steroid receptors in BR
action. However, BRs were shown not to bind directly to steroid receptors which demonstrate that BRs
act via steroid receptor-independent pathway(s). Concluding, BRs and their derivatives are capable to
inhibit growth of several human cancer cell lines and to inhibit angiogenesis-like behaviour of primary
endothelial cells in vitro, as well.
Keywords: Antiangiogenic activity, anticancer drugs, apoptosis, breast cancer, metastasis development,
cell cycle arrest.
