Abstract 1570: Silibinin inhibits invasive properties of human breast cancer cell line MDA-MB-231 through suppression of cathepsin B and extracellular signal-regulated kinase-mediated induction of matrix metalloproteinase 2 and 9

The purpose of the current study is to evaluate the effects of silibinin on human breast adenocarcinoma MDA-MB-231 cells. BrdU cell proliferation assay, Cell-based extracellular signal-regulated kinase (ERK) 1/2 activation assay, cathepsin B activity assay, Gelatin zymography and quantitative real-time RT-PCR were employed to appraise the effects of silibinin on DNA synthesis, ERK 1/2 phosphorylation, cathepsin B activity and gelatinolytic activity in MDA-MB-231 cells. Silibinin inhibited cell proliferation, ERK 1/2 activation, cathepsin B enzymatic levels and gelatinase activity in a dose-dependent manner. In addition, an expressive decrease in mRNA levels of cathepsin B, hyaluronidase-2 (Hyal-2), urokinase plasminogen activator receptor (uPAR), matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) coupled with a significant induction in transcriptional levels of tissue inhibitor of matrix metalloproteinase-2 (TIMP-2), Stefin A and Lipocalin 2 were observed. Altogether, these issues show for the first time that silibinin treatment could trammel cell growth and invasive features of a highly invasive human breast cancer cell line, MDA-MB-231, through suppression of ERK 1/2 both directly (through impeding ERK 1/2 phosphorylation) and indirectly (via transcriptional enhancement of Lipocalin 2). Furthermore, cramping enzymatic activity of cathepsin B by silibinin might cripple activation of gelatinases and thereby, reduces invasive potential in MDA-MB-231 cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1570.