Simultaneous blockade of VEGFR-1 and VEGFR-2 activation is necessary to efficiently inhibit experimental melanoma growth and metastasis formation.
Metastasis continues to be the major cause of morbidity and mortality in malignant melanoma. In our study, we explored whether inhibition of VEGFR-1 or VEGFR-2 signaling conveys distinct suppressive effects on B16 melanoma subcutaneous growth and metastasis formation. The inhibition of VEGFR-1 or -2 alone had no significant influence on both melanoma growth and metastasis formation. In contrast, simultaneous blockade of VEGFR-1 and -2 signaling strongly suppressed progression in both B16 tumor models. There was no expression of VEGFR-1 or -2 detectable on the B16 cells used, excluding the melanoma cells as direct therapeutic targets. Analyzing the contribution of progenitor-like cells during melanoma metastasis formation, we observed an enhanced proliferation and mobilization of VEGFR-1+ myeloid and VEGFR-2+ endothelial cells with progenitor potential by the induction of melanoma lung metastasis, which was not influenced by interference with VEGFR signaling. These results indicate that the antimetastatic effects exerted by combined inhibition of VEGFR-1 and -2 signaling were mediated via targeting cell populations other than progenitors only. Sole inhibition of VEGFR-1 signaling led to a strong reduction of the CD45-positive inflammatory infiltrate in the tumor tissue. However, the formation of lung metastasis was not affected, indicating that inhibition of the inflammatory response was not sufficient to efficiently block B16 melanoma metastasis development. Taken together, our data suggest that in the utilized B16 tumor models the blockade of both the inflammatory and the VEGFR-2-dependent angiogenic response are necessary to effectively inhibit solid tumor growth and formation of lung metastasis by B16 melanoma cells.
Gille
Jens
J
Department of Dermatology, J.W. Goethe-University, Frankfurt am Main, Germany.
Heidenreich
Regina
R
Pinter
Andreas
A
Schmitz
Judith
J
Boehme
Beatrice
B
Hicklin
Daniel J
DJ
Henschler
Reinhard
R
Breier
Georg
G
D000818:Animals; D019650:Hematopoietic Stem Cell Mobilization; D006801:Humans; D017493:Leukocyte Common Antigens / Q000032:analysis; D008175:Lung Neoplasms / Q000517:prevention & control / Q000556:secondary; D008546:Melanoma, Experimental / Q000473:pathology / Q000556:secondary / Q000628:therapy*; D051379:Mice; D008810:Mice, Inbred C57BL; D012190:Retroviridae / Q000235:genetics; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000037:antagonists & inhibitors* / Q000502:physiology; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors* / Q000502:physiology
D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2; D017493:Leukocyte Common Antigens