RESUMO
Antiangiogenesis-based cancer therapies, specifically those targeting the VEGF-A/VEGFR2 pathway, have been approved for subsets of solid tumors. However, these therapies result in an increase in hematologic adverse events. We surmised that both the bone marrow vasculature and VEGF receptor-positive hematopoietic cells could be impacted by VEGF pathway-targeted therapies. We used a mouse model of spontaneous breast cancer to decipher the mechanism by which VEGF pathway inhibition alters hematopoiesis. Tumor-bearing animals, while exhibiting increased angiogenesis at the primary tumor site, showed signs of shrinkage in the sinusoidal bone marrow vasculature accompanied by an increase in the hematopoietic stem cell-containing Lin-cKit(+)Sca1(+) (LKS) progenitor population. Therapeutic intervention by targeting VEGF-A, VEGFR2, and VEGFR3 inhibited tumor growth, consistent with observed alterations in the primary tumor vascular bed. These treatments also displayed systemic effects, including reversal of the tumor-induced shrinkage of sinusoidal vessels and altered population balance of hematopoietic stem cells in the bone marrow, manifested by the restoration of sinusoidal vessel morphology and hematopoietic homeostasis. These data indicate that tumor cells exert an aberrant systemic effect on the bone marrow microenvironment and VEGF-A/VEGFR targeting restores bone marrow function.
Assuntos
Medula Óssea/metabolismo , Neoplasias Mamárias Experimentais/irrigação sanguínea , Neoplasias Mamárias Experimentais/terapia , Receptores de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores , Fator A de Crescimento do Endotélio Vascular/antagonistas & inibidores , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/farmacologia , Feminino , Hematopoese , Células-Tronco Hematopoéticas/patologia , Homeostase , Imuno-Histoquímica , Neoplasias Mamárias Experimentais/metabolismo , Camundongos , Receptores de Fatores de Crescimento do Endotélio Vascular/imunologia , Receptores de Fatores de Crescimento do Endotélio Vascular/metabolismo , Fator A de Crescimento do Endotélio Vascular/imunologia , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
[This corrects the article on p. e55095 in vol. 8.].
RESUMO
Under steady state conditions, erythropoiesis occurs in the bone marrow. However, in mice, stress or tissue hypoxia results in increased erythropoiesis in the spleen. There is increasing evidence that the hematopoietic microenvironment, including endothelial cells, plays an important role in regulating erythropoiesis. Here, we show that short-term expression of constitutively active Akt in the endothelium of mice results in non-anemic stress erythropoiesis in the spleen. The initiation of this stress response was independent of erythropoietin and BMP4, and was observed in endothelial myrAkt1 mice reconstituted with wild-type bone marrow. Together, these data suggest that endothelial cell hyperactivation is a potentially novel pathway of inducing red cell production under stress.
