Dopamine regulates endothelial progenitor cell mobilization from mouse bone marrow in tumor vascularization
Debanjan Chakroborty, … , Partha Sarathi Dasgupta, Sujit Basu
Debanjan Chakroborty, … , Partha Sarathi Dasgupta, Sujit Basu
Published March 13, 2008
Citation Information: J Clin Invest. 2008;118(4):1380-1389. https://doi.org/10.1172/JCI33125.
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Research Article Oncology

Dopamine regulates endothelial progenitor cell mobilization from mouse bone marrow in tumor vascularization

Abstract

Mobilization of endothelial progenitor cells (EPCs) from the bone marrow and their subsequent participation in neovessel formation are implicated in tumor growth and neovascularization. As the neurotransmitter dopamine (DA) modulates adult endothelial cell function, we hypothesized that DA might have a regulatory role in mobilization of EPCs from the bone marrow niche. We show that there was a significant decrease in bone marrow DA content and an increase in EPC mobilization in tumor-bearing mice associated with tumor neovascularization. DA treatment of tumor-bearing mice inhibited EPC mobilization and tumor growth through its D2 receptors, as DA treatment failed to inhibit EPC mobilization in tumor-bearing mice treated with a specific DA D2 receptor antagonist and in tumor-bearing mice lacking the D2 receptor. In addition, we found that DA, through D2 receptors, exerted its inhibitory effect on EPC mobilization through suppression of VEGFA-induced ERK1/ERK2 phosphorylation and MMP-9 synthesis. These findings reveal a new link between DA and EPC mobilization and suggest a novel use for DA and D2 agents in the treatment of cancer and other diseases involving neovessel formation.

Authors

Debanjan Chakroborty, Uttio Roy Chowdhury, Chandrani Sarkar, Rathindranath Baral, Partha Sarathi Dasgupta, Sujit Basu

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Figure 7

DA, by acting on its D2 receptors, downregulates MMP-9 expression and activity in BM-derived CD45–VEGFR2+ cells without affecting TIMP-1.

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DA, by acting on its D2 receptors, downregulates MMP-9 expression and ac...
(A–E) Immunohistochemical analysis of BM sections showed increased expression of MMP-9 in BM cells of S180 tumor-bearing mice whereas normalization of MMP-9 expression was observed in wild-type (N) plus S180 plus DA-treated mice. S180 tumor-bearing D2(–/–) animals showed more robust expression of MMP-9 than respective controls. However, DA treatment had no effect on MMP-9 expression in these animals. (F) Concentration of pro–MMP-9 in overnight cultures of CD45–VEGFR2+ BM cells. Cells were isolated from BM by MACS cell-sorting system; pro–MMP-9 increased significantly in tumor-bearing animals. *P < 0.05. DA inhibited the increased pro–MMP-9 level to normal. However, prior eticlopride treatment abrogated this inhibitory effect of DA. In tumor-bearing D2(–/–) animals, culture showed higher pro–MMP-9 level, and DA treatment failed to show any effect on pro–MMP-9 concentration. (G) Assessment of MMP-9 activity in culture soup of CD45–VEGFR2+ cells from BM, by gelatin zymography. The separated cells from different experimental groups were cultured overnight in serum-free media, and the supernatant was assayed by gelatin zymography. Culture of CD45–VEGFR2+ cells from tumor-bearing hosts showed significantly increased activity of MMP-9 compared with normal, which was significantly inhibited by DA treatment. Culture of CD45–VEGFR2 + cells from tumor-bearing D2(–/–) mice showed significantly increased MMP-9 activity than respective control. However, DA treatment had no effect on MMP-9 activity. Figures are representative of 4 separate experiments for each group. Scale bars: 50 μm. (H–J) DA D2 receptors are present on EPCs, and DA treatment had no effect on TIMP-1. (H and I) Presence of DA D2 receptors in BM CD45–VEGFR2+ cells as evident from RT-PCR (H) and Western blot (I). (J) Treatment with DA had no effect on TIMP-1, the endogenous inhibitor of MMP-9 synthesis. TIMP-1 was evaluated by Western blot from CD45–VEGFR2+ BM cells. Figures are representative of 4 separate experiments for each group.