Abstract 5057: Mena at the nexus of chemotaxis and haptotaxis during tumor progression

Directed-cell migration is key step in the metastatic cascade, and multiple cues can promote local invasion. The most well studied mode of cell motility for metastasizing tumor cells is chemotaxis, the directional movement of cells attracted to a source of soluble cues. In contrast, haptotaxis, migration of cells on gradients of substrate-bound factors, remains poorly understood. Mena, an actin regulatory protein, plays an important role in cell motility and is upregulated in various cancers, driving migration in response to chemotactic and haptotactic cues. We have recently shown expression of the pro-metastatic isoform of Mena, MenaINV, increases sensitivity to growth factors (EGF, HGF and IGF) via dysregulation of the phosphatase PTP1B, as well as high concentrations of fibronectin (FN) via its interaction with the integrin α5β1. We hypothesized that MenaINV may also promote crosstalk between these two pathways to drive metastasis. First, we show that MenaINV-driven haptotaxis on FN gradients and FN-driven invasion requires crosstalk between α5β1 and EGFR. Indeed, we show evidence that MenaINV expression is associated high phosphorylation of EGFR in high FN environments in vitro and in human breast cancer databases. Second, we find that MenaINV promotes synergy between EGF and FN in vitro and in vivo, leading to hyper-invasive phenotypes that drive more invasion than which each cue alone. Finally, we show that MenaINV-driven haptotaxis, ECM reorganization and 3D invasion requires RCP-dependent recycling of α5β1 and EGFR. Together, our data demonstrate that MenaINV is a shared component of the machinery that mediates both haptotactic responses to FN and chemotactic responses to EGF, two pathways that promote tumor progression. Citation Format: Madeleine J. Oudin, Miles A. Miller, Tatsiana Kosciuk, Joelle Klazen, Alisha Lussiez, Douglas Lauffenburger, James E. Bear, Frank B. Gertler. Mena at the nexus of chemotaxis and haptotaxis during tumor progression. [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 5057.