title: Galectin-3 disruption impaired tumoral angiogenesis by reducing VEGF secretion from TGFβ1-induced macrophages.
abstract: In order to study the role of galectin-3 in tumor angiogenesis associated with tumor-associated macrophages (TAM) and tumor parenchyma, the galectin-3 expression was reconstituted in Tm1 melanoma cell line that lacks this protein. Galectin-3-expressing cells (Tm1G3) and mock-vector transfected cells (Tm1N3) were injected into wild-type (WT) and galectin-3 knockout (KO) C57Bl/6 mice. Tumors originated from Tm1G3 were larger in tumor volume with enlarged functional vessels, decreased necrotic areas, and increased vascular endothelial growth factor (VEGF) protein levels. Galectin-3-nonexpressing-cells injected into WT and KO showed increased levels of transforming growth factor beta 1 (TGFβ1) and, in WT animals this feature was also accompanied by increased VEGFR2 expression and its phosphorylation. In KO animals, tumors derived from galectin-3-expressing cells were infiltrated by CD68(+)-cells, whereas in tumors derived from galectin-3-nonexpressing-cells, CD68(+) cells failed to infiltrate tumors and accumulated in the periphery of the tumor mass. In vitro studies showed that Tm1G3 secreted more VEGF than Tm1N3 cells. In the latter case, TGFβ1 induced VEGF production. Basal secretion of VEGF was higher in WT-bone marrow-derived macrophages (BMDM) than in KO-BMDM. TGFβ1 induced secretion of VEGF only in WT-BMDM. Tm1G3-induced tumors had the Arginase I mRNA increased, which upregulated alternative macrophage (M2)/TAM induction. M2 stimuli, such as interleukin-4 (IL4) and TGFβ1, increased Arginase I protein levels and galectin-3 expression in WT- BMDM, but not in cells from KO mice. Hence, we report that galectin-3 disruption in tumor stroma and parenchyma decreases angiogenesis through interfering with the responses of macrophages to the interdependent VEGF and TGFβ1 signaling pathways.
authors.affiliation: Laboratório de Oncologia Experimental-LIM24, Departamento de Radiologia e Oncologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil; Depto. de Radiologia e Oncologia, Centro de Investigação Translacional em Oncologia, Instituto do Câncer do Estado de São Paulo, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil; Laboratório de Investigação Médica Radioisotopos-LIM/43, Departamento de Radiologia e Oncologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Camila Maria Longo
authors.initials: CM
authors.lastname: Machado
authors.forename: Luciana Nogueira Sousa
authors.initials: LN
authors.lastname: Andrade
authors.forename: Verônica Rodrigues
authors.initials: VR
authors.lastname: Teixeira
authors.forename: Fabrício Falconi
authors.initials: FF
authors.lastname: Costa
authors.forename: Camila Morais
authors.initials: CM
authors.lastname: Melo
authors.forename: Sofia Nascimento
authors.initials: SN
authors.lastname: dos Santos
authors.forename: Suely
authors.initials: S
authors.lastname: Nonogaki
authors.forename: Fu-Tong
authors.initials: FT
authors.lastname: Liu
authors.forename: Emerson Soares
authors.initials: ES
authors.lastname: Bernardes
authors.forename: Anamaria Aranha
authors.initials: AA
authors.lastname: Camargo
authors.forename: Roger
authors.initials: R
authors.lastname: Chammas
mesh_terms: D000818:Animals; D019175:DNA Methylation; D037502:Galectin 3 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D008545:Melanoma / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D053773:Transforming Growth Factor beta1 / Q000235:genetics*; D059016:Tumor Microenvironment; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: D037502:Galectin 3; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A
keywords: Angiogenesis; galectin-3; melanoma; tumor microenvironment