SEMA3A partially reverses VEGF effects through binding to neuropilin-1

Abstract

Cross-talk between hematopoietic stem cells (HSCs) and bone marrow stromal cells (BMSCs) is essential for HSCs regulation and leukemogenesis. Studying bone marrow of myelodysplasia patients, a pre-leukemic condition, we found mRNA overexpression of vascular endothelial growth factor A (VEGFA) in CD34 HSCs and semaphorin 3A (SEMA3A) in BMSCs. To better understand the role of VEGFA and SEMA3A in leukemogenesis, we recruited 30 myelodysplastic syndrome (MDS) patients, 29 acute myeloid leukemia (6 secondary to MDS) patients and 12 controls. We found higher VEGFA expression in de novo AML patients (without prior MDS) group (p=0.0073) and higher SEMA3A expression in all BMSCs patient's samples compared to control group. We then overexpressed VEGFA in an acute myelogenous leukemia cell line, KG1 cells, and in normal CD34 cells. This overexpression increased KG1 (p=0.045) and CD34 cell (p=0.042) viability and KG1 (p=0.042) and CD34 cell (p=0.047) proliferation. Moreover, KG1 and CD34 cells overexpressing VEGFA also had increased proliferation when co-cultured with human marrow stromal HS5 cells (p=0.045 and p=0.02, respectively). However, co-culture of these transformed cells with HS5 cells overexpressing SEMA3A reduced KG1 (p=0.004) and CD34 (p=0.009) proliferation. Co-culture of KG1 transformed cells with HS27 cells overexpressing SEMA3A reduced KG1 proliferation as well (p=0.01). To investigate whether the dominant SEMA3A effect over VEGFA could be due to competition for neuropilin1 receptor (NRP1), we performed immunoprecipitation with anti-NRP1 antibody of cell extracts of co-cultured KG1 and HS5 cells, induced or not by VEGFA and SEMA3A recombinant proteins. Results showed a preferential association of NRP1 with SEMA3A, suggesting that SEMA3A can partially reverse the effects caused by the VEGFA preventing its binding with the NRP1 receptor. Since both hematopoietic cells, leukemic and normal, showed similar behavior, we suppose that the attempt to reversion of VEGF effects by SEMA3A is a homeostatic phenomenon in the hematopoietic niche. Finally, we conclude that VEGFA overexpression confers AML cell advantages and SEMA3A may partially reverse this effect; thus, SEMA3A protein combined with VEGFA inhibitors could be beneficial for AML treatment.

Neuropilins, as Relevant Oncology Target: Their Role in the Tumoral Microenvironment

“…It is generally lost during tumor progression (Niland and Eble, 2019). In a VEGFA+/SEMA3A+ environment, NRP1 binds preferentially SEMA3A (Palodetto et al, 2017). Cells with a higher VEGF expression as compared to SEMA3A expression have promigratory characteristics.…”

Anti-angiogenic effects of the DPP-4 inhibitor linagliptin via inhibition of VEGFR signalling in the mouse model of oxygen-induced retinopathy

“…However, despite its anti-inflammatory properties in other retinopathy models, in this study linagliptin showed no effect on major proinflammatory cytokines in the OIR model [10]. Anti-inflammatory effects are associated with proangiogenic responses in the retina, as key proinflammatory pathways can inhibit the activity of VEGF-induced VEGFR signalling, as has been described elsewhere in detail for the semaphorin 3A (SEMA3A)-neuropilin 1 (NRP1) axis [34][35][36].…”

A Preliminary Study of the Effect of Semaphorin 3A and Acitretin on the Proliferation, Migration, and Apoptosis of HaCaT Cells

“…[24] Sema3A may act as a potent tumor suppressor in tumor cells growth by inhibiting tumor angiogenesis and VEGF function. [252627] Little is yet known about the role of Sema3A in the pathogenesis of psoriasis. Activated keratinocytes in psoriasis have the feature of excessive growth, which is similar to what is seen in tumor cells, but in benign progression.…”