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Glioblastoma (GBM) is a complex ecosystem that includes a heterogeneous tumor population and the tumor-immune microenvironment (TIME), prominently containing tumor-associated macrophages (TAM) and microglia. Here, we demonstrated that β2-microglobulin (B2M), a subunit of the class I major histocompatibility complex (MHC-I), promotes the maintenance of stem-like neoplastic populations and reprograms the TIME to an anti-inflammatory, tumor-promoting state. B2M activated PI3K/AKT/mTOR signaling by interacting with PIP5K1A in GBM stem cells (GSC) and promoting MYC-induced secretion of transforming growth factor-β1 (TGFβ1). Inhibition of B2M attenuated GSC survival, self-renewal, and tumor growth. B2M-induced TGFβ1 secretion activated paracrine SMAD and PI3K/AKT signaling in TAMs and promoted an M2-like macrophage phenotype. These findings reveal tumor-promoting functions of B2M and suggest that targeting B2M or its downstream axis may provide an effective approach for treating GBM. Significance: β2-microglobulin signaling in glioblastoma cells activates a PI3K/AKT/MYC/TGFβ1 axis that maintains stem cells and induces M2-like macrophage polarization, highlighting potential therapeutic strategies for targeting tumor cells and the immunosuppressive microenvironment in glioblastoma.

Glioblastoma (GBM) is a complex ecosystem that includes a heterogeneous tumor population and the tumor-immune microenvironment (TIME), prominently containing tumor-associated macrophages (TAM) and microglia. Here, we demonstrated that β2-microglobulin (B2M), a subunit of the class I major histocompatibility complex (MHC-I), promotes the maintenance of stem-like neoplastic populations and reprograms the TIME to an anti-inflammatory, tumor-promoting state. B2M activated PI3K/AKT/mTOR signaling by interacting with PIP5K1A in GBM stem cells (GSC) and promoting MYC-induced secretion of transforming growth factor-β1 (TGFβ1). Inhibition of B2M attenuated GSC survival, self-renewal, and tumor growth. B2M-induced TGFβ1 secretion activated paracrine SMAD and PI3K/AKT signaling in TAMs and promoted an M2-like macrophage phenotype. These findings reveal tumor-promoting functions of B2M and suggest that targeting B2M or its downstream axis may provide an effective approach for treating GBM.Significance:β2-microglobulin signaling in glioblastoma cells activates a PI3K/AKT/MYC/TGFβ1 axis that maintains stem cells and induces M2-like macrophage polarization, highlighting potential therapeutic strategies for targeting tumor cells and the immunosuppressive microenvironment in glioblastoma.

Supplementary Figure from β2-Microglobulin Maintains Glioblastoma Stem Cells and Induces M2-like Polarization of Tumor-Associated Macrophages

Background Glioblastomas (GBMs) display striking dysregulation of metabolism to promote tumor growth. Glioblastoma stem cells (GSCs) adapt to regions of heterogeneous nutrient availability, yet display dependency on de novo cholesterol biosynthesis. The transcription factor Sterol Regulatory Element-Binding Protein 2 (SREBP2) regulates cholesterol biosynthesis enzymes and uptake receptors. Here, we investigate adaptive behavior of GSCs under different cholesterol supplies. Methods In silico analysis of patient tumors demonstrated enrichment of cholesterol synthesis associated with decreased angiogenesis. Comparative gene expression of cholesterol biosynthesis enzymes in paired GBM specimens and GSCs were performed. In vitro and in vivo loss-of-function genetic and pharmacologic assays were conducted to evaluate the effect of SREBP2 on GBM cholesterol biosynthesis, proliferation, and self-renewal. Chromatin immunoprecipitation quantitative real-time PCR was leveraged to map the regulation of SREBP2 to cholesterol biosynthesis enzymes and uptake receptors in GSCs. Results Cholesterol biosynthetic enzymes were expressed at higher levels in GBM tumor cores than in invasive margins. SREBP2 promoted cholesterol biosynthesis in GSCs, especially under starvation, as well as proliferation, self-renewal, and tumor growth. SREBP2 governed the balance between cholesterol biosynthesis and uptake in different nutrient conditions. Conclusions SREBP2 displays context-specific regulation of cholesterol biology based on its availability in the microenvironment with induction of cholesterol biosynthesis in the tumor core and uptake in the margin, informing a novel treatment strategy for GBM.

A high-pressure hot-pressing process was applied to densify a commercial boron carbide-titanium diboride (B4C-TiB2) powder mixture. Nearly fully dense (98.6%) materials were obtained at 1 700 °C under a pressure of 100 MPa. Compared to the sintering temperature required to achieve similar results when a pressure of only 30 MPa was applied, the sintering temperature was found to decrease by about 200 °C under pressure of 100 MPa. Analysis of the thermodynamics and microstructure showed that the plastic deformation of the B4C grains induced by high pressure dominated the densification mechanism when high pressure was applied. Furthermore, higher pressure resulted in remarkably improved mechanical properties of the composites, which could be traced back to the generation of stacking faults in the B4C grains and aggregation of TiB2.

To compare the clinical efficacy differences between relaxing needling combined with rehabilitation training and rehabilitation training alone for medial collateral ligament (MCL) injury of knee joint.Sixty cases of MCL injury were randomly assigned into an observation group (30 cases, one case dropping out) and a control group (30 cases, two cases dropping out). Patients in the control group were treated with rehabilitation training; based on the treatment of control group, patients in the observation group were additionally treated with relaxing needles atAfter treatment, VAS scores were apparently reduced and the Lysholm scores were obviously increased in the two groups (allRelaxing needling combined with rehabilitation training can effectively improve the swel-ling, pain and other symptoms of MCL injury, which is superior to rehabilitation training alone.