Dioscin decreases M2 polarization via inhibiting a positive feedback loop between RBM47 and NF-κB in glioma.

BACKGROUND: The role of the glioblastoma (GBM) microenvironment is pivotal in the development of gliomas. Discovering drugs that can traverse the blood-brain barrier and modulate the tumor microenvironment is crucial for the treatment of GBM. Dioscin, a steroidal saponin derived from various kinds of plants and herbs known to penetrate the blood-brain barrier, has shown its powerful anti-tumor activity. However, little is known about its effects on GBM microenvironment. METHODS: Bioinformatics analysis was conducted to assess the link between GBM patients and their prognosis. Multiple techniques, including RNA sequencing, immunofluorescence staining, Western blot analysis, RNA-immunoprecipitation (RIP) assays, and Chromatin immunoprecipitation (CHIP) analysis were employed to elucidate the mechanism through which Dioscin modulates the immune microenvironment. RESULTS: Dioscin significantly impaired the polarization of macrophages into the M2 phenotype and enhanced the phagocytic ability of macrophages in vitro and in vivo. A strong correlation between high expression of RBM47 in GBM and a detrimental prognosis for patients was demonstrated. RNA-sequencing analysis revealed an association between RBM47 and the immune response. The inhibition of RBM47 significantly impaired the recruitment and polarization of macrophages into the M2 phenotype and enhanced the phagocytic ability of macrophages. Moreover, RBM47 could stabilize the mRNA of inflammatory genes and enhance the expression of these genes by activating the NF-κB pathway. In addition, NF-κB acts as a transcription factor that enhances the transcriptional activity of RBM47. Notably, we found that Dioscin could significantly inhibit the activation of NF-κB and then downregulate the expression of RBM47 and inflammatory genes protein. CONCLUSION: Our study reveals that the positive feedback loop between RBM47 and NF-κB could promote immunosuppressive microenvironment in GBM. Dioscin effectively inhibits M2 polarization in GBM by disrupting the positive feedback loop between RBM47 and NF-κB, indicating its potential therapeutic effects in GBM treatment.

Lysine-40 succinylation of TAGLN2 induces glioma angiogenesis and tumor growth through regulating TMSB4X.

Protein lysine succinylation (Ksucc) represents an important regulatory mechanism of tumor development. In this work, the difference of protein Ksucc between HCMEC/D3 co-cultured with U87 (glioma endothelia cells, GEC) and without U87 (normal endothelia cells, NEC) was investigated using TMT labeling and affinity enrichment followed by high-resolution LC-MS/MS analysis. Interestingly, TAGLN2 was highly succinylated at K40 in GEC (15.36 folds vs. NEC). Compared to the Vector group, TAGLN2WT and a succinylation-mimetic TAGLN2K40E greatly promoted the angiogenesis of glioma in vitro and in vivo. Furthermore, the adhesion and metastasis of U87 co-cultured with GEC in the TAGLN2WT or TAGLN2K40E group were also significantly promoted. This was consistent with the increased expression of VE-cadherin and actin cytoskeleton remodeling induced by TAGLN2 K40succ in GEC. In addition, high K40succ of TAGLN2 was associated with poor prognosis in patients with glioma. Overexpression of TAGLN2K40E also markedly promoted the proliferation and migration of glioma cells, further analysis of in vivo xenograft tumors showed that there was a significant decrease in tumor size and angiogenesis in the TAGLN2K40R group. Notably, the co-localization of TMSB4X and TAGLN2 mainly in the nucleus and cytoplasm of glioma cells was detected by immunofluorescence staining. We identified TMSB4X as a potential target of TAGLN2, which was proved to interact with TAGLN2WT rather than TAGLN2K40A. And the inhibition of TMSB4X could markedly attenuate the proliferation and migration of glioma cells induced by TAGLN2 K40succ. The results revealed K40succ of TAGLN2 could be a novelty diagnosis and therapeutic target for gliomas.

Lnc00462717 regulates the permeability of the blood-brain tumor barrier through interaction with PTBP1 to inhibit the miR-186-5p/Occludin signaling pathway.

Blood-brain tumor barrier (BTB) severely restricts the efficient delivery of chemotherapeutic drugs into brain tumor tissue, which is a critical obstacle for glioma treatment. Recently, long noncoding RNAs (lncRNAs) have shown as regulation factors of numerous biological processes. In this study, we identified that Lnc00462717 was upregulated in glioma endothelial cells (GECs), and that knockdown of Lnc00462717 significantly increased the BTB permeability. Both bioinformatics and RNA immunoprecipitation (RIP) results revealed that Lnc00462717 interacts with polypyrimidine tract binding protein (PTBP1). Moreover, overexpression of PTBP1 significantly reversed the increase in BTB permeability caused by siLnc00462717. Furthermore, the binding sites between miR-186 and PTBP1 as well as between miR-186 and 3'UTR of Occludin mRNA were confirmed by RIP and luciferase assays, respectively. And the interaction of Lnc00462717 and PTBP1 significantly facilitated the binding of PTBP1 to 3'UTR of Occludin mRNA and then blocked the miR-186-5p-induced downregulation of Occludin. In addition, we identified that knockdown of Lnc00462717 or overexpression of miR-186-5p increased the accumulation of doxorubicin (Dox) in brain glioma via the ultrafast liquid chromatography-mass spectrometry system (UFLC-MS/MS system) and decreased the intracranial glioma volume in BALB/c nude mice. Taken together, these results show a novel molecular pathway in BTB that may provide a potential innovative strategy for glioma therapy.

Long non-coding RNA SNHG12promotes the proliferation and migration of glioma cells by binding to HuR.

Long non-coding RNAs (lncRNAs) play important roles in biological processes and provide a novel approach with which to understand the molecular mechanisms responsible for glioma. Previous studies have demonstrated that lncRNA small nucleolar RNA host gene 12 (SNHG12) is involved in cell growth and migration. However, the accurate expression pattern of SNHG12 in glioma and the possible associations between this pattern and the clinicopathological characteristics of glioma cohorts are not yet known. The present study investigated the role of lncRNA SNHG12 in the development and progression of glioma, as well as the potential diagnostic value of SNHG12 in patients with glioma. The levels of SNHG12 were detected in resected specimens from patients and in glioma cell lines using reverse transcription-quantitative polymerase chain reaction. The potential effects of SNHG12 on the viability, mobility and apoptosis of glioma cells were evaluated using in vitro assays. The association between SNHG12 and Hu antigen R (HuR) was also determined using RNA immunoprecipitation (RIP) and RNA pull-down assays. The results revealed that SNHG12 was significantly upregulated in glioma tissues and cell lines. High levels of SNHG12 were associated with the deterioration of patients with glioma. Patients with high levels of SNHG12 exhibited a reduced 5-year overall survival rate (compared to those with lower levels), particularly in cohorts with high-grade carcinoma (III-IV). The silencing of SNHG12 expression by RNA interference led to a reduced viability and mobility, and in an increased apoptosis of human glioma cells. Furthermore, RIP and RNA pull-down assays demonstrated that SNHG12 was associated with and was stabilized by HuR. The findings of the present study thus identify a novel therapeutic target in glioma.