RESUMO
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMO
Resistance towards VEGF-centered anti-angiogenic therapy still represents a substantial clinical challenge. We report here that mast cells alter the proliferative and organizational state of endothelial cells which reduces the efficacy of anti-angiogenic therapy. Consequently, absence of mast cells sensitizes tumor vessels for anti-angiogenic therapy in different tumor models. Mechanistically, anti-angiogenic therapy only initially reduces tumor vessel proliferation, however, this treatment effect was abrogated over time as a result of mast cell-mediated restimulation of angiogenesis. We show that mast cells secrete increased amounts of granzyme b upon therapy, which mobilizes pro-angiogenic laminin- and vitronectin-bound FGF-1 and GM-CSF from the tumor matrix. In addition, mast cells also diminish efficacy of anti-angiogenic therapy by secretion of FGF-2. These pro-angiogenic factors act beside the targeted VEGFA-VEGFR2-axis and reinduce endothelial cell proliferation and angiogenesis despite the presence of anti-angiogenic therapy. Importantly, inhibition of mast cell degranulation with cromolyn is able to improve efficacy of anti-angiogenic therapy. Thus, concomitant mast cell-targeting might lead to improved efficacy of anti-angiogenic therapy.Resistance towards VEGF-centered anti-angiogenic therapy is an important clinical challenge. Here, the authors show that mast cells mediate resistance to anti-angiogenetic inhibitors by altering the proliferative and organizational state of endothelial cells through mobilization of FGF-1 and GM-CSF from the tumor matrix and secretion of FGF-2.
Assuntos
Inibidores da Angiogênese/farmacologia , Células Endoteliais/metabolismo , Granzimas/metabolismo , Mastócitos/metabolismo , Animais , Antiasmáticos/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cromolina Sódica/farmacologia , Células Endoteliais/efeitos dos fármacos , Matriz Extracelular/efeitos dos fármacos , Matriz Extracelular/metabolismo , Fator 1 de Crescimento de Fibroblastos/efeitos dos fármacos , Fator 1 de Crescimento de Fibroblastos/metabolismo , Fator 2 de Crescimento de Fibroblastos/efeitos dos fármacos , Fator 2 de Crescimento de Fibroblastos/metabolismo , Fator Estimulador de Colônias de Granulócitos e Macrófagos/efeitos dos fármacos , Fator Estimulador de Colônias de Granulócitos e Macrófagos/metabolismo , Células Endoteliais da Veia Umbilical Humana , Laminina/metabolismo , Mastócitos/efeitos dos fármacos , Camundongos , Neoplasias/irrigação sanguínea , Neoplasias/tratamento farmacológico , Neovascularização Patológica/metabolismo , Fator A de Crescimento do Endotélio Vascular/efeitos dos fármacos , Fator A de Crescimento do Endotélio Vascular/metabolismo , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/efeitos dos fármacos , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismo , Vitronectina/metabolismoRESUMO
Multiple myeloma is a mostly incurable malignancy characterized by the expansion of a malignant plasma cell (PC) clone in the human bone marrow (BM). Myeloma cells closely interact with the BM stroma, which secretes soluble factors that foster myeloma progression and therapy resistance. Growth arrest-specific gene 6 (Gas6) is produced by BM-derived stroma cells and can promote malignancy. However, the role of Gas6 and its receptors Axl, Tyro3 and Mer (TAM receptors) in myeloma is unknown. We therefore investigated their expression in myeloma cell lines and in the BM of myeloma patients and healthy donors. Gas6 showed increased expression in sorted BMPCs of myeloma patients compared with healthy controls. The fraction of Mer(+) BMPCs was increased in myeloma patients in comparison with healthy controls whereas Axl and Tyro3 were not expressed by BMPCs in the majority of patients. Downregulation of Gas6 and Mer inhibited the proliferation of different myeloma cell lines, whereas knocking down Axl or Tyro3 had no effect. Inhibition of the Gas6 receptor Mer or therapeutic targeting of Gas6 by warfarin reduced myeloma burden and improved survival in a systemic model of myeloma. Thus, the Gas6-Mer axis represents a novel candidate for therapeutic intervention in this incurable malignancy.
