OLFML2A Downregulation Inhibits Glioma Proliferation Through Suppression of Wnt/β-Catenin Signaling

Abstract

Background: Glioma is a highly heterogeneous and lethal tumor with extremely poor prognosis. Through analysis of TCGA data, we found that OLFML2A was significantly upregulated in glioma tissues and positively correlated with glioma grade and worse prognosis. However, the molecular function of OLFML2A and its underlying mechanism in glioma remain unclear.Methods: The expression of OLFML2A in glioma was determined by immunohistochemistry (IHC). Celigo assay, MTT assay and flow cytometry were utilized to evaluate the effects of OLFML2A on glioma proliferation and apoptosis. Gene chip microarray analysis and ingenuity pathway analysis were used to investigate the potential regulatory mechanisms of OLFML2A, which were further assessed by q-PCR, western blotting and IHC. An animal transplanting glioma model and spectral computed tomography scan were used to verify OLFML2A expression in vivo.Results: In this study, we found that the expression of OLFML2A was significantly upregulated in glioma specimens and positively correlated with pathological grades in glioma patients. Moreover, Kaplan-Meier survival analysis of TCGA data revealed that glioma patients with higher expression of OLFML2A had shorter overall survival. Importantly, when we knocked down the expression of OLFML2A in glioma cells, cell proliferation was inhibited, and apoptosis was promoted. Mechanistically, downregulation of OLFML2A inhibited Wnt/β-catenin signaling by directly reducing the level of stabilized β-catenin and upregulating the expression of amyloid precursor protein (APP) to indirectly suppress β-catenin, leading to repression of MYC, CD44 and CSKN2A2 expression. Furthermore, we found that OLFML2A downregulation clearly suppressed the growth of subcutaneous glioma and intracranial transplantation of glioma by inhibiting Wnt/β-catenin pathway-dependent cell proliferation.Conclusion: Our data indicate the oncogenic effect of OLFML2A in glioma through regulation of Wnt/β-catenin signaling, which may provide a novel therapeutic target for glioma.