Abstract 4606: Novel mechanism for suppression of human colorectal cancer cell proliferation through induction of Wnt9A and suppression of β-catenin by resveratrol
Authors: Ali Irshad , Medegan Bani , Braun Donald 
Published: July 2016

Abstract
Dysregulation of the Wnt pathway in histologically distinct cancers has been studied extensively. The canonical Wnt pathway (CWP) utilizing β-catenin is one of the major drivers for proliferation. In contrast, the capacity of the non-canonical Wnt pathway (NCWP) to regulate proliferation has not been studied extensively in neoplastic tissues. Our earlier studies demonstrated that RV-mediated suppression of colorectal cancer (CRC) cell proliferation correlated with upregulated expression of several NCWP components. These results are consistent with the hypothesis that these upregulated NCWP components suppress CWP activity leading to proliferation inhibition. Of the NCWP components measured, the ligand Wnt9A was most prominently upregulated. Since the CWP utilizes β-catenin for its activity, the purpose of the present study was to determine whether induction of Wnt9A and suppression of CRC proliferation by RV can be correlated directly to modulation of β-catenin message and protein levels. This study was conducted on human CRC cells derived from surgical specimens (n = 5). Cell proliferation and apoptosis were determined by MTS and Caspase 3 assays, respectively. β-catenin protein levels were determined by ELISA and gene expression using quantitative RT-PCR Wnt pathway gene expression arrays. RV increased Wnt9A expression in CRC cells in a concentration-dependent manner. Wnt9A expression was increased by a mean of 8, 36 and 260 fold (p&lt;0.004, ANOVA) relative to media controls with RV concentrations of 5, 10 and 20 μg/ml, respectively. The increase in Wnt9A expression was associated with decreased total β-catenin protein by 21, 51 and 71% (p&lt;0.001, ANOVA), and active β-catenin protein by 17, 22 and 50% (p&lt;0.001, ANOVA). These effects were associated with significant inhibition of proliferation by 35, 54 and 66% relative to media controls with RV concentrations of 5, 10 and 20 μg/ml, respectively (p&lt;0.006, ANOVA) and a significant increase in apoptosis (p&lt;0.01, ANOVA). Significantly, mRNA levels for β-catenin were not affected by any concentration of RV. Finally, the suppression of CRC cell proliferation by RV was reversed by Wnt9A antibody and IWP-2, a Wnt ligand secretion inhibitor (p&lt;0.02, ANOVA). The induction of Wnt9A with subsequent suppression of β-catenin protein levels by resveratrol represents a novel mechanism for the suppression of canonical Wnt pathway-mediated CRC cell proliferation. These results suggest that interventions that stimulate the induction of non-canonical Wnt pathway components, and specifically Wnt9A, may be therapeutically beneficial for controlling proliferation of colorectal cancers.
Citation Format: Irshad Ali, Bani Medegan, Donald Braun. Novel mechanism for suppression of human colorectal cancer cell proliferation through induction of Wnt9A and suppression of β-catenin by resveratrol. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4606.