title: Tumor-derived osteopontin reprograms normal mammary fibroblasts to promote inflammation and tumor growth in breast cancer.
abstract: Breast tumors are characterized by an extensive desmoplastic stroma, abundantly populated by fibroblasts. Cancer-associated fibroblasts (CAF) support tumorigenesis by stimulating angiogenesis, cancer cell proliferation, and invasion. CAF also orchestrate tumor-promoting inflammation in multiple tumor types, including breast cancer. However, the mechanisms through which normal tissue fibroblasts are reprogrammed to tumor-promoting CAFs are mainly obscure. Here, we show that mammary fibroblasts can be educated by breast cancer cells to become activated to a proinflammatory state that supports malignant progression. Proteomic analysis of breast cancer cell-secreted factors identified the secreted proinflammatory mediator osteopontin, which has been implicated in inflammation, tumor progression, and metastasis. Osteopontin was highly secreted by mouse and human breast cancer cells, and tumor cell-secreted osteopontin activated a CAF phenotypes in normal mammary fibroblasts in vitro and in vivo. Osteopontin was sufficient to induce fibroblast reprogramming and neutralizing antibodies against osteopontin-blocked fibroblast activation induced by tumor cells. The ability of secreted osteopontin to activate mammary fibroblasts relied upon its known receptors CD44 and αVβ3 integrin. Strikingly, osteopontin silencing in tumor cells in vivo attenuated stromal activation and inhibited tumor growth. Our findings establish a critical functional role for paracrine signaling by tumor-derived osteopontin in reprograming normal fibroblasts into tumor-promoting CAFs.
authors.affiliation: Department of Pathology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Yoray
authors.initials: Y
authors.lastname: Sharon
authors.affiliation: Department of Pathology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel. Department of Obstetrics and Gynecology, LIS Maternity Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.
authors.forename: Yael
authors.initials: Y
authors.lastname: Raz
authors.affiliation: Department of Pathology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Noam
authors.initials: N
authors.lastname: Cohen
authors.affiliation: Department of Pathology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Amir
authors.initials: A
authors.lastname: Ben-Shmuel
authors.affiliation: Department of Pathology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Hila
authors.initials: H
authors.lastname: Schwartz
authors.affiliation: Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Tamar
authors.initials: T
authors.lastname: Geiger
authors.affiliation: Department of Pathology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel. netaerez@post.tau.ac.il.
authors.forename: Neta
authors.initials: N
authors.lastname: Erez
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D065150:Cellular Reprogramming; D005260:Female; D005347:Fibroblasts / Q000502:physiology*; D006801:Humans; D018960:Hyaluronan Receptors / Q000502:physiology; D007249:Inflammation / Q000209:etiology; D039302:Integrin alphaVbeta3 / Q000502:physiology; D051379:Mice; D053495:Osteopontin / Q000502:physiology*
chemical_list: C497483:CD44 protein, human; D018960:Hyaluronan Receptors; D039302:Integrin alphaVbeta3; D053495:Osteopontin