Abstract 4605: Metastasis-associated tumor cell phenotypes in TNBC is regulated by Wnt-beta-catenin pathway signals
Authors: Dey Nandini , Carlson Jennifer H. , De Pradip , Leyland-Jones Brian R. 
Published: July 2016

Introduction: Acquisitions of metastasis-associated phenotypes (MA) by Triple Negative Breast Cancer (TNBC) cells are imparted by genetic alterations which cause deregulation of different signaling pathways associated to those phenotypes. We have recently reported that an upregulation of the Wnt-beta-catenin pathway (WP) is one of the salient genetic features of TNBC and demonstrated that the WP signaling in TNBC is associated with poor prognosis and metastasis (Dey et al., 2013). We have also identified that the functional upregulation of secreted-MMP7, a transcriptional target of WP in TNBC is associated to the functional loss/absence of PTEN gene (Dey et al., 2013), the most common first event associated with basal-like subtype (Martins et al., 2012). Aim: In order to understand the relevance of WP pathway in the biology of metastasizing TNBC tumor cells, here we have undertaken a study in which the involvement of WP is tested in the context of MA phenotypes including (1) integrin-directed migration, (2) matrigel-invasion and (3) clonogenic growth and proliferation in 15 TNBC cell lines. Methods: CHIR9902, Wnt-C59, XAV939, sulindac sulfide, beta-catenin SiRNA as well as physiological stimulation of the WP (LWnt3A CM) were used for the study. Podia-parameters were studied using confocal microscopy for architecture of filamentous actin while matrigel invasion was studied by MMP7 specific caesin-zymography. Results: The collective% of alterations in CTNNB1, APC and DVL1 genes among total breast invasive carcinomas (TCGA 2012) were 17% in contrast to 46% breast invasive carcinomas, PAM50 Basal. A similar trend was observed among subtypes of BC from brca/tcga/pub2015 (cBioPortal). Wnt-C59, XAV939, sulindac sulfide and beta-catenin SiRNA (1) inhibited fibronectin-directed migration (2) decreased maximum relative distance from the origin and average velocity of the movement by real-time video microscopy, (3) altered cytoskeletal organization of the filamentous-actin and decreased the podia parameters, (4) decreased matrigel-invasion, and (6) inhibited cell proliferation and 3D colony formation. Mechanistically the treatment with sulindac sulfide and beta-catenin SiRNA decreased cellular levels of beta-catenin, active beta-catenin and MMP7 in the same TNBC cell lines wherein fibronectin-directed migration, invasion, and colony formation were found inhibited. LWnt3ACM stimulated cell proliferation, clonogenicity, migration and invasion was perturbed by WP modulators, sulindac sulfide and PI3K pathway inhibitor in brain-metastasis specific TNBC cells. Conclusion: Here we present the first conclusive evidence to demonstrate that the WP activation is functionally responsible for MA phenotypes in TNBC. Our data explains the why different components of the WP is upregulated in TNBC and how WP activation is associated with poor prognosis and metastasis in this subtype.

Citation Format: Nandini Dey, Jennifer H. Carlson, Pradip De, Brian R. Leyland-Jones. Metastasis-associated tumor cell phenotypes in TNBC is regulated by Wnt-beta-catenin pathway signals. [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 4605.