Protein disulfide-isomerase A4 confers glioblastoma angiogenesis promotion capacity and resistance to anti-angiogenic therapy

Abstract

Introduction Increasing evidence has revealed the key activity of protein disulfide isomerase A4 (PDIA4) in the endoplasmic reticulum stress (ERS) response. However, the role of PDIA4 in regulating glioblastoma (GBM)-specific pro-angiogenesis is still unknown. Methods The expression and prognostic role of PDIA4 were analyzed using a bioinformatics approach and were validated in 32 clinical samples and follow-up data. RNA-sequencing was used to search for PDIA4-associated biological processes in GBM cells, and proteomic mass spectrum (MS) analysis was used to screen for potential PDIA4 substrates. Western blotting, real-time quantitative polymerase chain reaction (RT-qPCR), and enzyme-linked immunosorbent assays (ELISA) were used to measure the levels of the involved factors. Cell migration and tube formation assays determined the pro-angiogenesis activity of PDIA4 in vitro. An intracranial U87 xenograft GBM animal model was constructed to evaluate the pro-angiogenesis role of PDIA4 in vivo. Results Aberrant overexpression of PDIA4 was associated with a poor prognosis in patients with GBM, although PDIA4 could also functionally regulate intrinsic GBM secretion of vascular endothelial growth factor-A (VEGF-A) through its active domains of Cys-X-X-Cys (CXXC) oxidoreductase. Functionally, PDIA4 exhibits pro-angiogenesis activity both in vitro and in vivo, and can be upregulated by ERS through transcriptional regulation of X-box binding protein 1 (XBP1). The XBP1/PDIA4/VEGFA axis partially supports the mechanism underlying GBM cell survival under ER stress. Further, GBM cells with higher expression of PDIA4 showed resistance to antiangiogenic therapy in vivo. Conclusions Our findings revealed the pro-angiogenesis role of PDIA4 in GBM progression and its potential impact on GBM survival under a harsh microenvironment. Targeting PDIA4 might help to improve the efficacy of antiangiogenic therapy in patients with GBM.

Development of a prognostic model for glioblastoma multiforme based on the expression levels of efferocytosis-related genes

“…Protein disulfide isomerase A4 (PDIA4) is a member of the multi-protein chaperone complex, performing diverse functions by interacting with its specific substrates [ 23 ]. A growing body of evidence demonstrated that aberrant PDIA4 expression level and its potential mechanisms participate in the development of numerous types of cancer, including GBM [ 24 ]. PDIA4 is a key promotor of GBM.…”

“…The upregulation of PDIA4 in GBM was particularly pronounced when compared to normal tissues. A growing body of evidence underscored the pivotal role of PDIA4 in the endoplasmic reticulum (ER) stress response [ 24 ]. In tumor microenvironments, various metabolic abnormalities collaborate to disrupt ER homeostasis in malignant and stromal cells, as well as immunocytes.…”

ALKBH5 is a prognostic factor and promotes the angiogenesis of glioblastoma

“…The procedure of tumor sample IHC staining was performed, and the quantification was calculated according to a previous publication strictly 22 .…”

The role of angiogenic growth factors in the immune microenvironment of glioma

“…A recent study reported that the expression level of VEGF is an independent risk factor for glioma prognosis ( 33 ). Studies have found that GBM cells express and secrete VEGFA protein, which was regulated by protein disulfide isomerase A4 in GBM cells ( 34 , 35 ). Another study of GBM has shown that VEGFA was dramatically overexpressed while no significant change of VEGFB expression was detected in GBM patients ( 36 ).…”