Abstract 5181: Dynamic cellular adhesivity of breast cancer cells conferred by CD44 varies with mesenchymal or epithelial phenotype

Abstract

Abstract CD44 is a highly pleiotropic molecule whose many structural variants and glycan modifications determine function, particularly with respect to cell adhesion. In this study, we investigated the E-selectin ligand function of CD44 and its relationship with the mesenchymal versus epithelial cell phenotypes of breast cancer cells. Real time RT-PCR analysis for epithelial and mesenchymal cell markers showed that MDA-MB-231 and Hs-578T breast cancer cells are mesenchymal-like cells, but BT-20 and MDA-MB-468 breast cancer cells are epithelial-like cells. Flow cytometry revealed that all cell lines expressed CD44. Further exploration of the expression of specific CD44 isoforms at the mRNA level (by real time RT-PCR) and at the protein level (by flow cytometry) showed that mesenchymal-like breast cancer cells predominantly expressed CD44s but nearly undetectable levels of CD44v isoforms. On the other hand, epithelial-like cells expressed CD44s as well as CD44v isoforms. These results indicate that there are divergent CD44 isoform expression patterns in mesenchymal-like versus epithelial-like breast cancer cell lines. Further distinctions were observed in CD44 function in cells of the two phenotypes. Western blot analysis demonstrated that CD44 expressed by BT-20 cells were positive for E-selectin ligand activity, whereas CD44 of MDA-MB-231 cells failed to exhibit such functionality. Moreover, CD44v isoforms expressed by BT-20 cells, but not CD44s by MDA-MB-231 cells, mediated E-selectin adhesion under physiological flow conditions. Despite the positive ligand activity, none of the CD44v isoforms expressed by BT20 cells possessed HECA-452 reactivity by Western blot analysis. This finding indicates the absence of conventional sialofucosylated carbohydrates and the presence of potentially novel E-selectin reactive glycans. Collectively, these results show that CD44 expressed by epithelial-like cells, but not mesenchymal-like cells, are functional E-selectin ligands. Our investigation therefore implies an association of breast cancer cell adhesivity with the epithelial phenotype. Thus, future studies mechanistically linking the E-selectin ligand activity of CD44 isoforms with epithelial-to-mesenchymal transition may provide targets for novel breast cancer diagnostics, prognostics, and therapeutics. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5181. doi:1538-7445.AM2012-5181