Glioblastoma (GBM) is a grade IV glioma highly aggressive and refractory to the therapeutic approaches currently in use. O-GlcNAcylation plays a key role for tumor aggressiveness and progression in different types of cancer; however, experimental evidence of its involvement in GBM are still lacking. Here, we show that O-GlcNAcylation plays a critical role in maintaining the composition of the GBM secretome, whereas inhibition of OGA activity disrupts the intercellular signaling via microvesicles. Using a label-free quantitative proteomics methodology, we identified 51 proteins in the GBM secretome whose abundance was significantly altered by activity inhibition of O-GlcNAcase (iOGA). Among these proteins, we observed that proteins related to proteasome activity and to regulation of immune response in the tumor microenvironment were consistently downregulated in GBM cells upon iOGA. While the proteins IGFBP3, IL-6 and HSPA5 were downregulated in GBM iOGA cells, the protein SQSTM1/p62 was exclusively found in GBM cells under iOGA. These findings were in line with literature evidence on the role of p62/IL-6 signaling axis in suppressing tumor aggressiveness and our experimental evidence showing a decrease in radioresistance potential of these cells. Taken together, our findings provide evidence that OGA activity may regulate the p62 and IL-6 abundance in the GBM secretome. We propose that the assessment of tumor status from the main proteins present in its secretome may contribute to the advancement of diagnostic, prognostic and even therapeutic tools to approach this relevant malignancy.

中文翻译：

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Thiamet G破坏O-GlcNAcylation蛋白促进GBM U87-MG细胞分泌基因组分子标记的变化

胶质母细胞瘤（GBM）是一种IV级神经胶质瘤，对目前使用的治疗方法具有高度的侵袭性和难治性。O-GlcNAcylation在不同类型的癌症中对肿瘤的侵袭性和进展起着关键作用。但是，仍缺乏其参与GBM的实验证据。在这里，我们表明，O-GlcNAcylation在维持GBM分泌组的组成中起着关键作用，而对OGA活性的抑制则通过微泡破坏了细胞间的信号传导。使用无标记的定量蛋白质组学方法，我们在GBM分泌组中鉴定出51种蛋白质，其丰度因O-GlcNAcase（iOGA）的活性抑制而显着改变。在这些蛋白质中，我们观察到，与iOGA结合后，GBM细胞中与蛋白酶体活性和肿瘤微环境中免疫应答调节有关的蛋白质始终被下调。尽管在GBM iOGA细胞中IGFBP3，IL-6和HSPA5蛋白被下调，但在iOGA下的GBM细胞中仅发现了SQSTM1 / p62蛋白。这些发现与有关p62 / IL-6信号轴在抑制肿瘤侵袭性中的作用的文献证据相符，并且我们的实验证据表明这些细胞的放射抗性潜力降低。综上所述，我们的发现提供了证据，证明OGA活性可能调节GBM分泌组中的p62和IL-6丰度。我们建议从其分泌蛋白中存在的主要蛋白质评估肿瘤状态可能有助于诊断的发展，