Integrin-mediated laminin-1 adhesion upregulates CXCR4 and IL-8 expression in pancreatic cancer cells

BackgroundWe have shown recently that α2β1 integrin-mediated type I collagen adhesion promotes a more malignant phenotype in pancreatic cancer cell lines than other extracellular matrix (ECM) proteins. MiaPaCa-2 cells, by contrast, do not express collagen-binding integrins, but are metastatic in our orthotopic mouse model and migrate maximally on laminin-1 (Ln-1). It has also been shown that CXCR4 and IL-8 expression correlates directly with metastasis in pancreatic cancer in vivo. We therefore examined the potential of the ECM to regulate CXCR4 and IL-8 expression in pancreatic cancer cells.MethodsWe cultured 8 pancreatic cancer cell lines on fibronectin (Fn), types I and IV collagen, Ln-1 and vitronectin (Vn), and examined cell lysates for CXCR4 by immunoblotting and media for IL-8 by ELISA. We also conducted cell migration assays with stromal-derived factor-1 (SDF-1) as the chemoattractant to examine integrin-binding specificity and CXCR4 function.ResultsAll cell lines expressed CXCR4 protein. MiaPaCa-2 cell growth on Ln-1 increased significantly CXCR4 and IL-8 expression relative to other ECM proteins. Migration inhibition studies showed that both the α6β1 and α3β1 integrins mediate MiaPaCa-2 migration on Ln-1. Growth studies showed further that CXCR4 expression on Ln-1 was mediated by the α6β1 integrin whereas IL-8 expression was mediated by both the α6β1 and α3β1 integrins. The expression of functional CXCR4 was also shown in migration assays, where SDF-1 significantly increased pancreatic cancer cell chemotaxis on Ln-1.ConclusionsThese data indicate that integrin-mediated Ln-1 adhesion upregulates CXCR4 and IL-8 expression and may play a mechanistic role in pancreatic cancer metastases.