Neprilysin regulates the progression of glioblastoma: an in-vitro study using siRNA mediated gene silencing and HDAC1 mediated upregulation of neprilysin in U87 MG cells

Neprilysin (NEP) is a neutral endopeptidase that has gained attention due to its ability to cleave diverse peptides such as fibroblast growth factor-2 (FGF-2), insulin-like growth factors (IGFs), substance P, amyloid-β, thymopentin etc. NEP plays an important role in the functioning of the central nervous system, cardiovascular system, and in pathologies such as Alzheimer's disease, hypertension, and various cancers. In breast, ovarian, prostate, and lung cancers, reduced NEP levels are associated with cancer progression. In Glioblastoma (GBM), the level of NEP is downregulated. This study aims to understand the role and expression pattern of NEP in GBM. A web-based tool, UALCAN, was utilized to understand the expression pattern of NEP in GBM, followed by patient survival analysis using the Cancer Genome Atlas (TCGA) data. Further, in-vitro scratch assays were performed on U87 MG cells to understand the effect of NEP silencing, as well as its upregulation using certain HDAC1 inhibitors identified through in-silico studies (melphalan, tasimelteon and panobinostat), to study the cancer progression. The UALCAN web tool revealed that NEP levels are downregulated in GBM. Additionally, the in-vitro scratch assay demonstrated that silencing of NEP augmented cell proliferation, whereas the upregulation of NEP using the HDAC1 inhibitors resulted in decreased cancer proliferation. These results suggest an inverse correlation between the NEP levels and GBM proliferation. The tumor suppression exhibited by NEP could be attributed to its degradation of mitogenic proteins such as FGF-2, IGFs etc. In conclusion, NEP can be a promising biomarker and a drug target against GBM.