Abstract 421: Epidermal growth factor-like repeats of tenascin C alter melanoma cell migration both directly and through alteration of the ECM

Abstract

Abstract In melanoma, the most aggressive type of skin cancer, invasion through the extracellular matrix (ECM) is a harbinger of dissemination and mortality. Highly upregulated in both primary invasive and metastatic melanoma is tenascin C (TNC), a hexameric ECM protein with a multidomain structure composed of the globular N-terminal domain, 14.5 epidermal growth factor (EGF)-like repeats, fibronectin-III like repeats and the C-terminal globular fibrinogen-like domain. Our group previously showed that the EGF-like repeats of TNC are able to bind the EGF receptor (EGFR) with μM affinity and preferentially activate the motogenic signaling cascades. Both normal melanocytes and melanoma cells migrate faster on surfaces coated with TNC. Therefore, we hypothesize that the increased levels of TNC in melanomas promote tumor cell migration and invasion heralding dissemination through enhanced EGFR signaling. We expressed EGF-like repeats of TNC (TNC-EGFL) in melanoma cell lines already expressing endogenous TNC and observed change in the cell morphology, and more importantly a prominent anti-adhesive phenotype. TNC-EGFL expressing cells attached with a four-hour lag compared to parental cell lines and detached to a greater extent in inverted centrifugation adhesion assays. This was not due to decreased viability of TNC-EGFL expressing cells as determined by dye exclusion assay. As this phenotype could not be reverted by adding anti-EGFR antibody, we speculate that EGFR signaling might be intracellular. In two-dimensional migration assays, TNC-EGFL expressing cells closed a gap more slowly, possibly due to inability to properly attach during migration, emphasizing the need of concerted action of different TNC domains in regulating migration. On the other hand, quantitative PCR array analysis of a panel of ECM and adhesion molecules revealed changes in matrix metalloproteinase (MMP) expression, specifically MMP-2, MMP-9 and MMP-14, and increase in TGF β1 expression, proteins associated with melanoma invasiveness and vasculogenic mimicry. These results imply that TNC-EGFL repeats are involved in melanoma invasion both by directly influencing cell migration and indirectly by altering the tumor microenvironment and may have implications for development of anti tumor therapies directed at the extracellular matrix. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 421. doi:10.1158/1538-7445.AM2011-421