Abstract C57: Snail transcription factor can regulate cathepsin L activity in prostate carcinomas

Prostate cancer (PCa) is the most frequently diagnosed cancer in men, the second leading cause of male cancer deaths in the U.S, and also presents the greatest racial disparity of any cancer in the U.S. The incidence and mortality of PCa is higher in African-American men (AA), compared to other ethnic groups. Snail transcription factor expression is increased in prostate cancer and associated with epithelial-mesenchymal transition (EMT), whereby epithelial cancer cells expressing epithelial markers such as E-cadherin transition into spindle-shaped mesenchymal cells expressing markers such as vimentin. Snail can turn on proteases like MMP-9 to increase degradation of basement membrane and extracellular matrix proteins prior to cancer cell invasion and migration. We have preliminary data showing that muscadine grape skin extract (MSKE), derived from muscadine grape (Vitis rotundifolia), a common red grape used to produce red wine can decrease Snail expression in prostate cancer cells. Cathepsin L is a cysteine cathepsin that is overexpressed in prostate cancer and involved in the repression of E-cadherin, a hallmark of EMT. We investigated whether there could be a link between Snail and Cathepsin L. We hypothesize that the Snail expression may be increased in African American tissue as compared to other races and that Snail can induce the increased activity of Cathepsin L which can be antagonized by MSKE. Initially, we examined the expression of Snail and Cathepsin L in prostate cancer cells by Western blot analysis and Cathepsin L Activity via Zymography. The cell lines utilized in this study are LNCaP, C4-2 (the aggressive subline of LNCaP), mesenchymal ARCaP (ARCaP-M) and epithelial ARCaP (ARCaP-E). Preliminary results suggest that Snail expression and Cathepsin L activity is high in prostate cancer cells compared to normal prostate epithelial cells. We also obtained human prostate cancer tissue from the Bahamas which we are currently staining for Snail and Cathepsin L, to compare to staining from tissue microarrays. We have observed so far that there is both Snail and Cathepsin L expression in the tissue samples. We then utilitized LNCaP and ARCaP-E prostate cancer cells stably transfected with an empty Neo vector (LNCaP Neo; ARCaP Neo) or constituitively active Snail cDNA (LNCaP Snail; ARCaP Snail) that have been shown previously to represent an EMT model, to examine Cathepsin L and Stat-3 activity. We observed that Snail overexpression led to increased Cathepsin L and Stat-3 activity compared to cells with the Neo vector. Additionally ARCaP-E cells overexpresing Snail, C4-2, or ARCaP-M cells treated with MSKE (5ug/mL and 20ug/mL) for a period of 72hrs led to decreased Cathepsin L and Stat-3 activity. Furthermore, MSKE reverted EMT as shown by increased E-cadherein expression, decreased vimentin expression and decrease in cell migration. Taken together, these findings suggest that Snail my increase Cathepsin L activity via the Stat-3 signaling pathway in prostate cancer cells and MSKE could potentially be a promising bioactive compound for human cancer prevention and therapy. Citation Format: Liza Burton, Peri Nappagan, Basil Smith, Manu Platt, Camille Ragin, Valerie Odero-Marah. Snail transcription factor can regulate cathepsin L activity in prostate carcinomas. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr C57. doi:10.1158/1538-7755.DISP13-C57