Sema3C signaling is an alternative activator of the canonical WNT pathway in glioblastoma

Regulation of cancer stem cells and immunotherapy of glioblastoma (Review)

Glioblastoma (GB) is one of the most adverse diagnoses in oncology. Complex current treatment results in a median survival of 15 months. Resistance to treatment is associated with the presence of cancer stem cells (CSCs). The present review aimed to analyze the mechanisms of CSC plasticity, showing the particular role of β-catenin in regulating vital functions of CSCs, and to describe the molecular mechanisms of Wnt-independent increase of β-catenin levels, which is influenced by the local microenvironment of CSCs. The present review also analyzed the reasons for the low effectiveness of using medication in the regulation of CSCs, and proposed the development of immunotherapy scenarios with tumor cell vaccines, containing heterogenous cancer cells able of producing a multidirectional antineoplastic immune response. Additionally, the possibility of managing lymphopenia by transplanting hematopoietic stem cells from a healthy sibling and using clofazimine or other repurposed drugs that reduce β-catenin concentration in CSCs was discussed in the present study.

The semaphorin 3A/neuropilin-1 pathway promotes clonogenic growth of glioblastoma via activation of TGF-β signaling

Glioblastoma (GBM) is the most lethal brain cancer with a dismal prognosis. Stem-like GBM cells (GSCs) are a major driver of GBM propagation and recurrence; thus, understanding the molecular mechanisms that promote GSCs may lead to effective therapeutic approaches. Through in vitro clonogenic growth-based assays, we determined mitogenic activities of the ligand molecules that are implicated in neural development. We have identified that semaphorin 3A (Sema3A), originally known as an axon guidance molecule in the CNS, promotes clonogenic growth of GBM cells but not normal neural progenitor cells (NPCs). Mechanistically, Sema3A binds to its receptor neuropilin-1 (NRP1) and facilitates an interaction between NRP1 and TGF-β receptor 1 (TGF-βR1), which in turn leads to activation of canonical TGF-β signaling in both GSCs and NPCs. TGF-β signaling enhances self-renewal and survival of GBM tumors through induction of key stem cell factors, but it evokes cytostatic responses in NPCs. Blockage of the Sema3A/NRP1 axis via shRNA-mediated knockdown of Sema3A or NRP1 impeded clonogenic growth and TGF-β pathway activity in GSCs and inhibited tumor growth in vivo. Taken together, these findings suggest that the Sema3A/NRP1/TGF-βR1 signaling axis is a critical regulator of GSC propagation and a potential therapeutic target for GBM.

Association between circ_0004365 and cisplatin resistance in esophageal squamous cell carcinoma

Cisplatin is one of the most predominant drugs for the chemotherapy of esophageal squamous cell carcinoma (ESCC); however, the underlying resistance mechanisms are still almost unknown. The present study performed RNA sequencing of human circular RNA (circRNA) in TE11 cells and cisplatin-resistant TE11 cells (TE11R). The expression profiles determined using CIRCexplorer2 revealed that the expression of circ_0004365, mapped on the Semaphorin 3C gene, was significantly greater in TE11R compared with in TE11. In reverse transcription-quantitative PCR, circ_0004365 expression was observed in human ESCC and non-tumor tissues and was significantly upregulated in ESCC tumor tissues after chemotherapy. Circ_0004365 expression was significantly upregulated in patients with poor pathological response (P=0.02). Furthermore, patients with advanced pT stage showed an upregulation in circ_0004365 expression after chemotherapy (P=0.02). The MTT assay revealed that knockdown of circ_0003465 in TE11 significantly decreased resistance to cisplatin. In conclusion, the present study suggested that circ_0004365 was associated with cisplatin resistance in ESCC and can be used as both a novel biomarker and a therapeutic target.

Exploring the role of m6A methylation regulators in glioblastoma multiforme and their impact on the tumor immune microenvironment

Although the role of N6-Methyladenosine (m6A) methylation factors has been established in multiple cancer types, its involvement in glioblastoma multiforme (GBM) remains limited. This study aims to explore the involvement of m6A regulators in GBM and examine their association with the tumor immune microenvironment (TIME). A comprehensive set of 24 candidate m6A RNA regulators was procured. Consensus clustering was performed based on these regulators to identify distinct GBM clusters. PD-L1 and PD-1 levels, immune cell infiltration, and immune scores were evaluated between two clusters. Prognostic signatures and correlation analysis with TIME were analyzed using Lasso and Spearman's analysis. GBM tissue was collected to verify the correlations. Eighteen m6A regulators (WTAP, YTHDF2, HNRNPC, CAPRIN1, YTHDF3, METTL14, GNL3, ZCCHC4, HNRNPD, YTHDF1, RBM15, PCIF1, RBM27, KIAA1429, MSI2, FTO, ALKBH5, and METTL3), PD-L1, and PD-1 were significantly upregulated in GBM tissue. These regulators were divided into two distinct molecular subtypes (clusters 1 and 2). Cluster 2 exhibited a significant increase in immune score, monocytes, M1 macrophages, activated mast cells, and eosinophils. HNRNPC, YWHAG, and ALKBH5 were significantly associated with TIME and positively correlated with PD-L1. Immune cell invasiveness profiles dynamically changed with copy number changes of these three m6A regulators. Finally, YWHAG and ALKBH5 were found to be independent prognostic indicators of GBM through risk analysis and were experimentally verified with clinical samples. YWHAG and ALKBH5 may be used as prognostic markers for patients with GBM. m6A methylation regulators may play an important role in regulating PD-L1/PD-1 expression and immune infiltration, thus having a significant impact on GBM TIME.