RhoA regulates translation of the Nogo-A decoy SPARC in white matter-invading glioblastomas

Citric acid promotes SPARC release in pancreatic cancer cells and inhibits the progression of pancreatic tumors in mice on a high-fat diet

Over the years, pancreatic cancer has experienced a global surge in incidence and mortality rates, largely attributed to the influence of obesity and diabetes mellitus on disease initiation and progression. In this study, we investigated the pathogenesis of pancreatic cancer in mice subjected to a high-fat diet (HFD) and observed an increase in citric acid expenditure. Notably, citrate treatment demonstrates significant efficacy in promoting tumor cell apoptosis, suppressing cell proliferation, and inhibiting tumor growth in vivo. Our investigations revealed that citrate achieved these effects by releasing secreted protein acidic and rich in cysteine (SPARC) proteins, repolarizing M2 macrophages into M1 macrophages, and facilitating tumor cell apoptosis. Overall, our research highlights the critical role of citric acid as a pivotal metabolite in the intricate relationship between obesity and pancreatic cancer. Furthermore, we uncovered the significant metabolic and immune checkpoint function of SPARC in pancreatic cancer, suggesting its potential as both a biomarker and therapeutic target in treating this patient population.

Targeting endothelial permeability in the EPR effect

The characteristics of the primary tumor blood vessels and the tumor microenvironment drive the enhanced permeability and retention (EPR) effect, which confers an advantage towards enhanced delivery of anti-cancer nanomedicine and has shown beneficial effects in preclinical models. Increased vascular permeability is a landmark feature of the tumor vessels and an important driver of the EPR. The main focus of this review is the endothelial regulation of vascular permeability. We discuss current challenges of targeting vascular permeability towards clinical translation and summarize the structural components and mechanisms of endothelial permeability, the principal mediators and signaling players, the targeted approaches that have been used and their outcomes to date. We also critically discuss the effects of the tumor-infiltrating immune cells, their interplay with the tumor vessels and the impact of immune responses on nanomedicine delivery, the impact of anti-angiogenic and tumor-stroma targeting approaches, and desirable nanoparticle design approaches for greater translational benefit.

Sphingosine-1-Phosphate Recruits Macrophages and Microglia and Induces a Pro-Tumorigenic Phenotype That Favors Glioma Progression

Glioblastoma is the most aggressive brain tumor in adults. Treatment failure is predominantly caused by its high invasiveness and its ability to induce a supportive microenvironment. As part of this, a major role for tumor-associated macrophages/microglia (TAMs) in glioblastoma development was recognized. Phospholipids are important players in various fundamental biological processes, including tumor-stroma crosstalk, and the bioactive lipid sphingosine-1-phosphate (S1P) has been linked to glioblastoma cell proliferation, invasion, and survival. Despite the urgent need for better therapeutic approaches, novel strategies targeting sphingolipids in glioblastoma are still poorly explored. Here, we showed that higher amounts of S1P secreted by glioma cells are responsible for an active recruitment of TAMs, mediated by S1P receptor (S1PR) signaling through the modulation of Rac1/RhoA. This resulted in increased infiltration of TAMs in the tumor, which, in turn, triggered their pro-tumorigenic phenotype through the inhibition of NFkB-mediated inflammation. Gene set enrichment analyses showed that such an anti-inflammatory microenvironment correlated with shorter survival of glioblastoma patients. Inhibition of S1P restored a pro-inflammatory phenotype in TAMs and resulted in increased survival of tumor-bearing mice. Taken together, our results establish a crucial role for S1P in fine-tuning the crosstalk between glioma and infiltrating TAMs, thus pointing to the S1P-S1PR axis as an attractive target for glioma treatment.

Nogo‑A/NgR signaling regulates stemness in cancer stem‑like cells derived from U87MG glioblastoma cells

Neurite outgrowth inhibitor A (Nogo-A), a member of the reticulon 4 family, is an axon regeneration inhibitor that is negatively associated with the malignancy of oligodendroglial tumors. It has been suggested that the Nogo-A/Nogo Receptor (NgR) pathway plays a promoting effect in regulating cancer stem-like cells (CSCs) derived from glioblastoma, indicating that Nogo-A could exert different roles in CSCs than those in parental cancer cells. In the present study, CSCs were generated from the human Uppsala 87 malignant glioma (U87MG) cell line. These U87MG-CSCs were characterized by the upregulation of CD44 and CD133, which are two markers of stemness. The expression levels of Nogo-A and the differentiation of U87MG-CSCs were investigated. In addition, the proliferation, invasion and colony formation U87MG-CSCs were examined. Using culture in serum-containing medium, U87MG-CSCs were differentiated into neuron-like cells specifically expressing MAP2, β-III-tubulin and nestin. Nogo-A was upregulated in U87MG-CSCs compared with parental cells. Knockdown of Nogo-A and inhibition of the Nogo-A/NgR signaling pathway in U87MG-CSCs markedly decreased cell viability, cell cycle entry, invasion and tumor formation, indicating that Nogo-A could regulate U87MG-CSC function. Moreover, Nogo-A was involved in intracellular ATP synthesis and scavenging of accumulated reactive oxygen species. Nogo-A/NgR pathway exerted protective effects against hypoxia-induced non-apoptotic and apoptotic cell death. These results suggest that Nogo-A plays an important role in regulating U87MG-CSCs via the Nogo-A/NgR signaling pathway. Nogo-A may also different roles in U87MG-CSCs compared with their parental cells.

Glioma invasion along white matter tracts: A dilemma for neurosurgeons

Invasive growth along white matter (WM) tracts is one of the most prominent clinicopathological features of glioma and is also an important reason for surgical treatment failure in glioma patients. A full understanding of relevant clinical features and mechanisms is of great significance for finding new therapeutic targets and developing new treatment regimens and strategies. Herein, we review the imaging and histological characteristics of glioma patients with WM tracts invasion and summarize the possible molecular mechanism. On this basis, we further discuss the correlation between glioma molecular typing, radiotherapy and tumor treating fields (TTFields) and the invasion of glioma along WM tracts.

ENTPD5: identification of splicing variants and their impact on cancer survival

NTPDase5 is a nucleotidase of the endoplasmic reticulum that plays an important role in proteostasis as a regulator of protein N-glycosylation. This enzyme was first identified in hamster as a proto-oncogene activated upon a single nucleotide deletion that causes a frameshift leading to a truncated protein. Truncated NTPDase5 proteins were detected in human samples, but an oncogene was never identified. Searching for transcript variants in the GenBank database and using TCGA data, we discovered that splice variants could originate truncated human NTPDase5 proteins. We identified three main splicing events in the ENTPD5 gene: alternative acceptors, exon skipping, and alternative terminators. The analysis of impact of splicing events in cancers showed that skipping of exon 11-the event that leads to truncated proteins similar in size to the hamster oncogene-does not affect the hazard ratio of most tumors and was, in fact, a protective factor in the only two cancer studies where it was significant. We also identified four main patterns of impact of ENTPD5 in cancer and a potential variant-specific regulation by miR-215. Our findings shed light on a two-decade uncertainty about the origin of truncated NTPDase5 and contribute to the characterization of its impacts in cancer.