Glioma pathogenesis related-2 (GLIPR2), an emerging Golgi membrane protein implicated in autophagy, has received limited attention in current scholarly discourse.
Leveraging extensive datasets, including The Cancer Genome Atlas (TCGA), Genotype Tissue Expression (GTEx), Human Protein Atlas (HPA), and Clinical Proteomic Tumor Analysis Consortium (CPTAC), we conducted a comprehensive investigation into GLIPR2 expression across diverse human malignancies. Utilizing UALCAN, OncoDB, MEXPRESS and cBioPortal databases, we scrutinized GLIPR2 mutation patterns and methylation landscapes. The integration of bulk and single-cell RNA sequencing facilitated elucidation of relationships among cellular heterogeneity, immune infiltration, and GLIPR2 levels in pan-cancer. Employing ROC and KM analyses, we unveiled the diagnostic and prognostic potential of GLIPR2 across diverse cancers. Immunohistochemistry provided insights into GLIPR2 expression patterns in a multicenter cohort spanning various cancer types. In vitro functional experiments, including transwell assays, wound healing analyses, and drug sensitivity testing, were employed to delineate the tumor suppressive role of GLIPR2.
GLIPR2 expression was significantly reduced in neoplastic tissues compared to its prevalence in healthy tissues. Copy number variations (CNV) and alterations in methylation patterns exhibited discernible correlations with GLIPR2 expression within tumor tissues. Moreover, GLIPR2 demonstrated diagnostic and prognostic implications, showing pronounced associations with the expression profiles of numerous immune checkpoint genes and the relative abundance of immune cells in the neoplastic microenvironment. This multifaceted influence was evident across various cancer types, with lung adenocarcinoma (LUAD) being particularly prominent. Notably, patients with LUAD exhibited a significant decrease in GLIPR2 expression within practical clinical settings. Elevated GLIPR2 expression correlated with improved prognostic outcomes specifically in LUAD. Following radiotherapy, LUAD cases displayed an increased presence of GLIPR2+ infiltrating cellular constituents, indicating a notable correlation with heightened sensitivity to radiation-induced therapeutic modalities. A battery of experiments validated the functional role of GLIPR2 in suppressing the malignant phenotype and enhancing treatment sensitivity.
In pan-cancer, particularly in LUAD, GLIPR2 emerges as a promising novel biomarker and tumor suppressor. Its involvement in immune cell infiltration suggests potential as an immunotherapeutic target.

A key mediator of macroautophagy/autophagy induction is the class III phosphatidylinositol 3-kinase complex I (PtdIns3K-C1) consisting of PIK3C3/VPS34, PIK3R4/VPS15, BECN1, and ATG14. Although several proteins are known to enhance or decrease PtdIns3K-C1 activity, our understanding of the molecular regulation of PtdIns3K-C1 is still incomplete. Previously, we identified a Golgi-associated protein, GLIPR2, in a screen for proteins that interact with amino acids 267-284 of BECN1, a region of BECN1 sufficient to induce autophagy when fused to a cell penetrating leader sequence. In this study, we used CRISPR-Cas9-mediated depletion of GLIPR2 in cells and mice to investigate the role of GLIPR2 in the regulation of autophagy and PtdIns3K-C1 activity. Depletion of GLIPR2 in HeLa cells increased autelophagic flux and generation of phosphatidylinositol 3-phosphate (PtdIns3P). GLIPR2 knockout resulted in less compact Golgi structures, which was also observed in autophagy-inducing conditions such as amino acid starvation or Tat-BECN1 peptide treatment. Importantly, the binding of GLIPR2 to purified PtdIns3K-C1 inhibited the in vitro lipid kinase activity of PtdIns3K-C1. Moreover, the tissues of glipr2 knockout mice had increased basal autophagic flux as well as increased recruitment of the PtdIns3P-binding protein, WIPI2. Taken together, our findings demonstrate that GLIPR2 is a negative regulator of PtdIns3K-C1 activity and basal autophagy.Abbreviations: ATG14: autophagy related 14; Baf A1: bafilomycin A1; BARA: β-α repeated, autophagy-specific; CQ: chloroquine; GFP: green fluorescent protein; GLIPR2: GLI pathogenesis related 2; HBSS: Hanks\' balanced salt solution; KO: knockout; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; PBS: phosphate-buffered saline; PtdIns3K-C1: phosphatidylinositol 3-kinase complex I; PtdIns3P: phosphatidylinositol-3-phosphate; SEM: standard error of the mean; WIPI2: WD repeat domain, phosphoinositide interacting 2.