title: PI3Kα activates integrin α4β1 to establish a metastatic niche in lymph nodes.
abstract: Lymph nodes are initial sites of tumor metastasis, yet whether the lymph node microenvironment actively promotes tumor metastasis remains unknown. We show here that VEGF-C/PI3Kα-driven remodeling of lymph nodes promotes tumor metastasis by activating integrin α4β1 on lymph node lymphatic endothelium. Activated integrin α4β1 promotes expansion of the lymphatic endothelium in lymph nodes and serves as an adhesive ligand that captures vascular cell adhesion molecule 1 (VCAM-1)(+) metastatic tumor cells, thereby promoting lymph node metastasis. Experimental induction of α4β1 expression in lymph nodes is sufficient to promote tumor cell adhesion to lymphatic endothelium and lymph node metastasis in vivo, whereas genetic or pharmacological blockade of integrin α4β1 or VCAM-1 inhibits it. As lymph node metastases accurately predict poor disease outcome, and integrin α4β1 is a biomarker of lymphatic endothelium in tumor-draining lymph nodes from animals and patients, these results indicate that targeting integrin α4β1 or VCAM to inhibit the interactions of tumor cells with the lymph node microenvironment may be an effective strategy to suppress tumor metastasis.
authors.affiliation: Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093-0819, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Garmy-Susini
authors.forename: Christie J
authors.initials: CJ
authors.lastname: Avraamides
authors.forename: Jay S
authors.initials: JS
authors.lastname: Desgrosellier
authors.forename: Michael C
authors.initials: MC
authors.lastname: Schmid
authors.forename: Philippe
authors.initials: P
authors.lastname: Foubert
authors.forename: Lesley G
authors.initials: LG
authors.lastname: Ellies
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Lowy
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Blair
authors.forename: Scott R
authors.initials: SR
authors.lastname: Vandenberg
authors.forename: Brian
authors.initials: B
authors.lastname: Datnow
authors.forename: Huan-You
authors.initials: HY
authors.lastname: Wang
authors.forename: David A
authors.initials: DA
authors.lastname: Cheresh
authors.forename: Judith
authors.initials: J
authors.lastname: Varner
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D018270:Carcinoma, Ductal, Breast / Q000473:pathology*; D002448:Cell Adhesion / Q000502:physiology; D004729:Endothelium, Lymphatic / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D039041:Integrin alpha4beta1 / Q000378:metabolism*; D008198:Lymph Nodes / Q000378:metabolism*; D042583:Lymphangiogenesis / Q000502:physiology; D051379:Mice; D009362:Neoplasm Metastasis / Q000503:physiopathology* / Q000517:prevention & control; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism* / Q000502:physiology
chemical_list: D039041:Integrin alpha4beta1; D019010:Vascular Cell Adhesion Molecule-1; D019869:Phosphatidylinositol 3-Kinases