Abstract
Chemokines are secreted into the tumor microenvironment by tumor-infiltrating inflammatory cells as well as by tumor cells. Chemokine receptors mediate agonist-dependent cell responses, including migration and activation of several signaling pathways. In the present study we show that several human melanoma cell lines and melanoma cells on macroscopically infiltrated lymph nodes express the chemokine receptors CXCR3 and CXCR4. Using the highly invasive melanoma cell line BLM, we demonstrate that the chemokine Mig, a ligand for CXCR3, activates the small GTPases RhoA and Rac1, induces a reorganization of the actin cytoskeleton, and triggers cell chemotaxis and modulation of integrin VLA-5- and VLA-4-dependent cell adhesion to fibronectin. Furthermore, the chemokine SDF-1alpha, the ligand of CXCR4, triggered modulation of beta(1) integrin-dependent melanoma cell adhesion to fibronectin. Additionally, Mig and SDF-1alpha activated MAPKs p44/42 and p38 on melanoma cells. Expression of functional CXCR3 and CXCR4 receptors on melanoma cells indicates that they might contribute to cell motility during invasion as well as to regulation of cell proliferation and survival.
Highlights
The chemokines are a family of low molecular weight cytokines that elicit cell migration responses and activation of several signaling pathways [1,2,3,4]
Cells—Analysis by flow cytometry of several melanoma cell lines indicated that CXCR3, a receptor for chemokines Mig, IP-10, and interferon-inducible T cell ␣-chemoattractant, was moderately expressed mainly on the highly invasive BLM cell line and to a lesser degree on SK-Mel 37 cells, whereas low or no expression was detected on MeWo and A375 cells (Fig. 1A)
Melanoma cells might encounter different chemokines produced in the tumor microenvironment by infiltrating inflammatory cells, such as macrophages and activated T lymphocytes, as well as by tumor cells [13] or displayed on the endothelium at metastasis sites
Summary
The chemokines are a family of low molecular weight cytokines that elicit cell migration responses and activation of several signaling pathways [1,2,3,4]. Using the highly invasive melanoma cell line BLM, we demonstrate that the chemokine Mig, a ligand for CXCR3, activates the small GTPases RhoA and Rac1, induces a reorganization of the actin cytoskeleton, and triggers cell chemotaxis and modulation of integrin VLA-5- and VLA-4-dependent cell adhesion to fibronectin.
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