Brassinosteroids (BRs) represent a large group of plant steroids which include more than 70 congerners distributed from lower to higher plants. BRs have been detected and isolated from seeds, fruits, leaves, galls and pollen. Physiological functions proposed for BRs include plant cell elongation, cell division and modulation of stress responses when applied at very low concentrations [1]. Some medically oriented applications of BRs have also been already reported [2–4]. Wachsman et al.[2, 3] showed that some natural BRs (28-homocastasterone, 28-homobrassinolide) and their synthetic analogues have in vitro antiviral activity against several pathogen viruses, like herpes simplex virus type 1 (HSV-1), arenaviruses and measles virus (MV).
The aim of our study was to determine whether natural types of BRs can affect the viability, proliferation, differentiation, apoptosis and expression of some cell cycle related proteins in cancer cell lines. Cytotoxic activity of BRs were tested in vitro by Calcein AM assay. IC50 values were estimated for human breast adenocarcinoma cell lines (MCF- 7– estrogen-sensitive, MDA-MB-468– estrogen-insensitive), human acute lymphoblastic leukemia cell line (CEM) and human myeloma cell line (RPMI 8226)[5]. TUNEL, DNA ladder assay, and immunoblotting were used for analysis of changes of cell viability, proliferation, differentiation and apoptosis.
28-Homocastasterone inhibited the viability of cancer cell lines and significantly reduced or induced the expression of p21, p27, p53, cyclins, proteins of Bcl-2 family, and ER-alpha. The antiproliferative properties can be usable for development of new brassinosteroid-derived generation of anticancer drugs.
Acknowledgements: This work was supported by the grant MSM 6198959216 of the Ministry of Education of Czech Republic.
References: 1. Clouse, S.D. (2002), Brassinosteroids. In: The Arabidopsis book. American Society of Plant Biologists, Washington D.C., pp. 1–23. 2. Wachsman, M.B. et al. (2002), Antivir. Chem. Chemother. 13: 61–66. 3. Wachsman, M.B. et al. (2000), Antivir. Chem. Chemother. 11: 71–77. 4. Michelini, F.M. et al. (2004), Steroids 69: 713–720. 5. Swaczynová, J. et al. (2006), Polish J. Chem. 80: 629–635.
