title: Combined blockade of integrin-α4β1 plus cytokines SDF-1α or IL-1β potently inhibits tumor inflammation and growth.
abstract: Tumor-associated macrophages promote tumor growth by stimulating angiogenesis and suppressing antitumor immunity. Thus, therapeutics that inhibit macrophage recruitment to tumors may provide new avenues for cancer therapy. In this study, we showed how chemoattractants stromal cell-derived growth factor 1 alpha (SDF-1α) and interleukin 1 beta (IL-1β) collaborate with myeloid cell integrin-α4β1 to promote tumor inflammation and growth. We found that SDF-1α and IL-1β are highly expressed in the microenvironments of murine lung, pancreatic, and breast tumors; surprisingly, SDF-1α was expressed only by tumor cells, whereas IL-1β was produced only by tumor-derived granulocytes and macrophages. In vivo, both factors directly recruited proangiogenic macrophages to tissues, whereas antagonists of both factors suppressed tumor inflammation, angiogenesis, and growth. Signals induced by IL-1β and SDF-1α promoted the interaction of talin and paxillin with the cytoplasmic tails of integrin-α4β1, thereby stimulating myeloid cell adhesion to endothelium in vitro and in vivo. Inhibition of integrin-α4β1, SDF-1α, or IL-1β was sufficient to block tumor inflammation and growth, and the combined blockade of these molecules greatly accentuated these effects. Furthermore, antagonists of integrin-α4β1 inhibited chemotherapy-induced tumor inflammation and acted synergistically with chemotherapeutic agents to suppress tumor inflammation and growth. These results show that targeting myeloid cell recruitment mechanisms can be an effective approach to suppress tumor progression.
authors.affiliation: Moores UCSD Cancer Center, University of California, San Diego, California, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Schmid
authors.forename: Christie J
authors.initials: CJ
authors.lastname: Avraamides
authors.forename: Philippe
authors.initials: P
authors.lastname: Foubert
authors.forename: Yuval
authors.initials: Y
authors.lastname: Shaked
authors.forename: Sang Won
authors.initials: SW
authors.lastname: Kang
authors.forename: Robert S
authors.initials: RS
authors.lastname: Kerbel
authors.forename: Judith A
authors.initials: JA
authors.lastname: Varner
mesh_terms: D000818:Animals; D039481:CD11b Antigen / Q000032:analysis; D002465:Cell Movement; D054377:Chemokine CXCL12 / Q000037:antagonists & inhibitors* / Q000502:physiology; D007249:Inflammation / Q000517:prevention & control*; D039041:Integrin alpha4beta1 / Q000037:antagonists & inhibitors* / Q000502:physiology; D053583:Interleukin-1beta / Q000037:antagonists & inhibitors* / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D022423:Myeloid Cells / Q000502:physiology; D009369:Neoplasms / Q000473:pathology / Q000628:therapy*; D051419:Paxillin / Q000502:physiology; D016608:Talin / Q000502:physiology
chemical_list: D039481:CD11b Antigen; D054377:Chemokine CXCL12; C509295:ITGAM protein, human; D039041:Integrin alpha4beta1; D053583:Interleukin-1beta; D051419:Paxillin; D016608:Talin