P4HA2, a prognostic factor, promotes glioma proliferation, invasion, migration and EMT through collagen regulation and PI3K/AKT pathway

Prolyl-4-hydroxylase subunit 2 (P4HA2), as a member of collagen modification enzymes, is induced under hypoxic conditions with essential roles in the collagen maturation, deposition as well as the remodeling of extracellular matrix(ECM). Mounting evidence has suggested that deregulation of P4HA2 is common in cancer. However, the expression pattern and molecular mechanisms of P4HA2 in glioma remain unknown. Here, we demonstrate that P4HA2 is overexpressed in glioma and inversely correlates with patient survival. Knockdown of P4HA2 inhibits proliferation, migration, invasion, and epithelial-to-mesenchymal transition (EMT)-like phenotype of glioma cells in vitro and suppressed tumor xenograft growth in vivo. Mechanistically, bioinformatics analysis shows that ECM-receptor interaction and PI3K/AKT pathway are the most enriched pathways of the co-expressed genes with P4HA2. Furthermore, P4HA2 mRNA was positively correlated with mRNA expressions of a series of collagen genes, but not mRNA of PI3K or AKT1/2. Conversely, both the protein expressions of collagens and phosphorylated PI3K/AKT could be downregulated either by silencing of P4HA2 expression or inhibition of its prolyl hydroxylase. Moreover, the inhibitory effects on the migration, invasion and the EMT-related molecules by P4HA2 knockdown can be recapitulated by the Akt phosphorylation activator. Taken together, our findings for the first time reveal an oncogenic role of P4HA2 in the glioma malignancy. By regulating the expression of fibrillar collagens and the downstream PI3K/AKT signaling pathway, it may serve as a potential anti-cancer target for the treatment of glioma. HighlightsP4HA2 is overexpressed and correlated with poor prognosis in glioma. P4HA2 depletion inhibits glioma proliferation, migration, invasion and EMT-like phenotype in vitro and tumorigenesis in vivo. P4HA2 depletion attenuates the PI3K/AKT signaling pathway in a collagen-dependent manner.