Laminin-10 Mediates Basal and EGF-Stimulated Motility of Human Colon Carcinoma Cells via α3β1 and α6β4 Integrins

Abstract

Signals from the epidermal growth factor (EGF) receptor and integrin-dependent adhesion to laminin contribute to the progression and metastasis of colonic tumors. However, little is know about the mechanisms by which these signals cooperate. Recently, we have reported that the colon cancer cell line LIM1215 secretes and adhere to autocrine laminin-10 via multiple integrin receptors and that EGF stimulates spreading of these cells on the same substrate. In this report, we investigate the effect of EGF and laminin-10 on colon cancer cell migration in vitro. EGF stimulates migration of LIM1215 cells in a wound healing assay. The response to EGF is inhibited by anti-EGF receptor antibody 528, the EGF receptor kinase inhibitor AG-1478, or the MAP kinase kinase inhibitor PD98059 but not the PI3-K inhibitor wortmannin. Using Transwell migration chambers, we demonstrate that laminin-10 but not collagen-I, collagen-IV, or a commercial preparation of human placental laminin is a potent motility factor for LIM1215 cells. The migration response to laminin-10 is increased upon stimulation of the cells with EGF and correlates with the up-regulation of α6β4 integrin expression as measured by analysis of Triton X-100-soluble cellular extracts. The results from integrin inhibition experiments indicate that basal migration on laminin-10 is mediated by α3β1 but not α2β1 nor α6β4 integrins. Alpha3 blocking antibodies also inhibited EGF-stimulated chemokinetic migration of LIM1215 cells on laminin-10. However, in contrast to unstimulated cells, α6 or β4 integrin-blocking antibodies inhibited the migration of EGF-stimulated cells by up to 50%. Taken together, these results support the cooperative role of EGF receptor and laminin-10 on colon cancer cell motility and suggest a critical role for both the α3β1 and the α6β4 integrins in this process.