Interplay between VEGF-A and cMET signaling in human vestibular schwannomas and schwann cells

Abstract

Vestibular schwannoma (VS), the fourth most common intracranial tumor, arises from the Schwann cells of the vestibular nerve. Although several pathways have been independently implicated in VS pathobiology, interactions among these pathways have not been explored in depth. We have investigated the potential cross-talk between hepatocyte growth factor (HGF) and vascular endothelial growth factor-A (VEGF-A) in human VS, an interaction that has been described in other physiological and pathological cell types. We affirmed previous findings that VEGF-A signaling is aberrantly upregulated in VS, and established that expression of HGF and its receptor cMET is also significantly higher in sporadic VS than in healthy nerves. In primary human VS and Schwann cell cultures, we found that VEGF-A and HGF signaling pathways modulate each other. siRNAs targeting cMET decreased both cMET and VEGF-A protein levels, and siRNAs targeting VEGF-A reduced cMET expression. Additionally, siRNA-mediated knockdown of VEGF-A or cMET and pharmacologic inhibition of cMET decreased cellular proliferation in primary human VS cultures. Our data suggest cross-talk between these 2 prominent pathways in VS and highlight the HGF/cMET pathway as an additional important therapeutic target in VS.

Keywords:

• hepatocyte growth factor
• Schwann cells
• siRNA
• cross-talk
• vascular endothelial growth factor
• vestibular schwannoma

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

Acknowledgements

We would like to thank Drs. Kevin Emerick, Michael McKenna and Daniel Lee at Massachusetts Eye and Ear Infirmary and Drs. Frederick Barker and Robert Martuza at Massachusetts General Hospital for assistance in human sample collection.

Funding

This study was supported by the National Institute on Deafness and Other Communication Disorders Grants T32 DC00038 (SD, KMS) and K08DC010419 (KMS), the Bertarelli Foundation (KMS) and the US. Department of Defense Grant W81XWH-14–1–0091 (KMS).