Tumor-derived extracellular vesicles: how they mediate glioma immunosuppression.

Gliomas, the most common malignant brain tumor, present a grim prognosis despite available treatments such as surgical resection, temozolomide (TMZ) therapy, and radiation therapy. This is due to their aggressive growth, high level of immunosuppression, and the blood-brain barrier (BBB), which obstruct the effective exchange of therapeutic drugs. Gliomas can significantly affect differentiation and function of immune cells by releasing extracellular vesicles (EVs), resulting in a systemic immunosuppressive state and a highly immunosuppressive microenvironment. In the tumor immune microenvironment (TIME), the primary immune cells are regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), and tumor-associated macrophages (TAMs). In particular, glioma-associated TAMs are chiefly composed of monocyte-derived macrophages and brain-resident microglia. These cells partially exhibit characteristics of a pro-tumorigenic, anti-inflammatory M2-type. Glioma-derived EVs can hijack TAMs to differentiate into tumor-supporting phenotypes or directly affect the maturation of peripheral blood monocytes (PBMCs) and promote the activation of MDSCs. In addition, EVs impair the ability of dendritic cells (DCs) to process antigens, subsequently hindering the activation of lymphocytes. EVs also impact the proliferation, differentiation, and activation of lymphocytes. This is primarily evident in the overall reduction of CD4 + helper T cells and CD8 + T cells, coupled with a relative increase in Tregs, which possess immunosuppressive characteristics. This study investigates thoroughly how tumor-derived EVs impair the function of immune cells and enhance immunosuppression in gliomas, shedding light on their potential implications for immunotherapy strategies in glioma treatment.

Molecular Mechanism of the Protective Effects of M2 Microglia on Neurons: A Review Focused on Exosomes and Secretory Proteins.

Microglia, as innate immune cells in the brain, closely monitor changes in the internal environment and participate in the maintenance of homeostasis in the central nervous system (CNS). Microglia can be polarized to the M1 or M2 phenotype in response to various stimuli in vivo or in vitro, affecting the functions of peripheral neurons. M2 microglia have attracted increasing attention in recent years owing to their beneficial effects on various diseases and injuries of the CNS, such as traumatic brain injury, stroke, Alzheimer's disease and multiple sclerosis. They exert neuroprotective effects by various mechanisms, e.g., suppressing inflammation, promoting the degradation of misfolded and aggregated proteins, promoting neurite growth, enhancing neurogenesis, inhibiting autophagy and apoptosis, promoting myelination, maintaining blood-brain barrier integrity, and enhancing phagocytic activity.This review summarizes the molecular mechanisms by which M2 microglia exert protective effects on neurons and provides a reference for the selection of therapeutic targets for CNS diseases.

Biglycan up-regulated vascular endothelial growth factor (VEGF) expression and promoted angiogenesis in colon cancer.

Biglycan is an important component of the extracellular matrix, which belongs to the small leucine-rich proteoglycan family. Recent studies have shown that biglycan expression is elevated in many tumor tissues and implies poor prognosis, such as colon cancer. However, the molecular mechanism of biglycan in colon cancer has not been investigated. The present study aimed to investigate the effects of biglycan on vascular endothelial growth factor (VEGF) expression in colon cancer cells and on tumor angiogenesis in vivo. Biglycan overexpression vectors were constructed, and the stable biglycan overexpression in human colon cancer cell lines (HCT116 cells) was established by G418 screening. The stable cell clones were subsequently used to initiate tumor xenografts in nude mice. Our results showed that biglycan overexpression notably up-regulated the levels of VEGF in colon cancer cells, which was further confirmed by immunohistochemistry analysis in the xenograft colon tumors. Moreover, high levels of biglycan promoted angiogenesis and colon tumor growth, as evidenced by the increased cell viability, colon tumor size, and weight, as well as the CD34 expression. Additionally, we found that the extracellular signal-regulated kinase (ERK) signaling pathway was activated by biglycan in colon cancer cells. The ERK inhibitor PD98059 dramatically reversed the increased expression of VEGF induced by biglycan. Taken together, our results indicated that biglycan up-regulated VEGF expression in colon cancer cells and promoted tumor angiogenesis. Biglycan-mediated VEGF regulation may correlate with the activation of the ERK signaling pathway. Therefore, biglycan may be a promising target for anti-angiogenic therapy for cancer.

Relationship of serum MMP-7 levels for colorectal cancer: a meta-analysis.

This meta-analysis aimed to identify the value of serum matrix metalloproteinase-7 (MMP-7) levels for the diagnosis of colorectal cancer (CRC). Through searching the following electronic databases: Cochrane Library (Issue 12, 2014), Web of Science (1945∼2014), PubMed (1966∼2014), CINAHL (1982∼2014), EMBASE (1980∼2014), and CBM (1982∼2014), related articles were determined without any language restrictions. Stata statistical software (Version 12.0, Stata Corporation, College Station, TX, USA) was chosen to deal with statistical data. Standard mean difference (SMD) and its corresponding 95 % confidence interval (95 % CI) were calculated to clarify the correlation between serum MMP-7 levels and CRC. Seven clinical case-control studies which recruited 430 CRC patients and 357 healthy subjects were selected for statistical analysis. The main findings of our meta-analysis showed that the serum MMP-7 level in CRC patients was significantly higher than that in control subjects (SMD = 2.15, 95 % CI = 1.46∼2.84, P < 0.001). Ethnicity-stratified analysis indicated a higher serum MMP-7 level in CRC patients than that of control subjects among the Asians and the Caucasians (Asians: SMD = 2.83, 95 % CI = 1.76∼3.91, P < 0.001; Caucasians: SMD = 1.06, 95 % CI = 0.46∼1.66, P = 0.001; respectively). The present meta-analysis indicated that the increased serum level of MMP-7 may be connected with the development of CRC; thus, serum levels of MMP-7 could be an independent biomarker for CRC patients.

Research progress on mechanisms of ischemic stroke: Regulatory pathways involving Microglia.

Microglia, as the intrinsic immune cells in the brain, are activated following ischemic stroke. Activated microglia participate in the pathological processes after stroke through polarization, autophagy, phagocytosis, pyroptosis, ferroptosis, apoptosis, and necrosis, thereby influencing the injury and repair following stroke. It has been established that polarized M1 and M2 microglia exhibit pro-inflammatory and anti-inflammatory effects, respectively. Autophagy and phagocytosis in microglia following ischemia are dynamic processes, where moderate levels promote cell survival, while excessive responses may exacerbate neurofunctional deficits following stroke. Additionally, pyroptosis and ferroptosis in microglia after ischemic stroke contribute to the release of harmful cytokines, further aggravating the damage to brain tissue due to ischemia. This article discusses the different functional states of microglia in ischemic stroke research, highlighting current research trends and gaps, and provides insights and guidance for further study of ischemic stroke.

Emerging role of autophagy in colorectal cancer: Progress and prospects for clinical intervention.

Autophagy is a physiological mechanism in which cells degrade themselves and quickly recover the degraded cell components. Recent studies have shown that autophagy plays an important role in the occurrence, development, treatment, and prognosis of colorectal cancer. In the early stages of colorectal cancer, autophagy can inhibit the production and development of tumors through multiple mechanisms such as maintaining DNA stability, inducing tumor death, and enhancing immune surveillance. However, as colorectal cancer progresses, autophagy may mediate tumor resistance, enhance tumor metabolism, and other pathways to promote tumor development. Therefore, intervening in autophagy at the appropriate time has broad clinical application prospects. This article summarizes the recent research progress of autophagy and colorectal cancer and is expected to provide new theoretical basis and reference for clinical treatment of colorectal cancer.

Knockdown of biglycan expression by RNA interference inhibits the proliferation and invasion of, and induces apoptosis in, the HCT116 colon cancer cell line.

Biglycan is an important component of the extracellular matrix, and it is also a member of small leucine-rich proteoglycan family. Previous studies indicated that the expression of biglycan was increased in a variety of tumor tissues, including colon cancer. However, the mechanisms underlying its effects in colon cancer remain to be fully elucidated. In the present study, the effects of biglycan knockdown on colon cancer cell proliferation, migration, invasion and apoptosis were investigated. The mRNA expression levels of biglycan in the HCT116 colon cancer cell line were downregulated using RNA interference, and the stably transfected cell line was obtained through G418 screening for subsequent experiments. The results revealed that downregulation of the expression of biglycan suppressed cell proliferation and caused a cell cycle arrest at the G0/G1 phase. The results of the western blot analysis also revealed that the expression levels of cell cycle­associated proteins, including cyclin A and cyclin D1, were markedly decreased following silencing of biglycan, whereas the expression levels of p21 and p27 were markedly increased compared with that of the short hairpin RNA control group. Furthermore, the decreased expression of biglycan inhibited colon cancer cell migration and invasion, and induced apoptosis. A complete inhibition of the p38 signaling pathway with SB203580 effectively reversed the increase in apoptotic cell numbers induced by biglycan downregulation. Taken together, the results of the present study indicated that biglycan exerts an important role in cell proliferation, migration, invasion and apoptosis in colon cancer, and that biglycan regulates the p38 MAPK signaling pathway by exerting an antiapoptotic effect. Therefore, biglycan may represent a putative target for colon cancer gene therapy.