Invasion of glioma cells through confined space requires membrane tension regulation and mechano-electrical coupling via Plexin-B2.

Glioblastoma (GBM) is a malignant brain tumor with uncontrolled invasive growth. Here, we demonstrate how GBM cells usurp guidance receptor Plexin-B2 to gain biomechanical plasticity for polarized migration through confined space. Using live-cell imaging to track GBM cells negotiating microchannels, we reveal active endocytosis at cell front and filamentous actin assembly at rear to propel GBM cells through constrictions. These two processes are interconnected and governed by Plexin-B2 that orchestrates cortical actin and membrane tension, shown by biomechanical assays. Molecular dynamics simulations predict that balanced membrane and actin tension are required for optimal migratory velocity and consistency. Furthermore, Plexin-B2 mechanosensitive function requires a bendable extracellular ring structure and affects membrane internalization, permeability, phospholipid composition, as well as inner membrane surface charge. Together, our studies unveil a key element of membrane tension and mechanoelectrical coupling via Plexin-B2 that enables GBM cells to adapt to physical constraints and achieve polarized confined migration.

Emerging nanomedical strategies for direct targeting of pediatric and adult diffuse gliomas.

High-grade gliomas, in particularly diffuse midline glioma, H3K27-altered in children and glioblastoma in adults, are the most lethal brain tumour with a dismal prognosis. Developments in modern medicine are constantly being applied in the search for a cure, although finding the right strategy remains elusive. Circumventing the blood-brain barrier is one of the biggest challenges when it comes to treating brain tumours. The cat and mouse game of finding the Trojan horse to traverse this barrier and deliver therapeutics to the brain has been a long and hard-fought struggle. Research is ongoing to find new and feasible ways to reach specific targets in the brain, with a special focus on inoperable or recurring brain tumours. Many options and combinations of options have been tested to date and continue to be so in the search to find the most effective and least toxic treatment paradigm. Although improvements are often small and slow, some of these strategies have already shown promise, shining a light of hope that finding the cure is feasible. In this review, we discuss recent findings that elucidate promising but atypical strategies for targeting gliomas and the implications that this work has on developing new treatment regimens.

Brief Report: Group Sex and Methamphetamine Use Fuel an Explosive Epidemic of Hepatitis C Among HIV-Infected Men Who Have Sex With Men in Bangkok, Thailand.

BACKGROUND: Increased rates of hepatitis C virus (HCV) infection among HIV-infected men who have sex with men (MSM) and who deny injecting drugs have been reported in resource-rich settings. SETTING: We measured HCV prevalence and incidence in a predominantly MSM cohort with acute HIV infection in Bangkok, Thailand. METHODS: In 2009-2018, participants with acute HIV infection were enrolled into the SEARCH010/RV254 cohort. HCV antibody was measured at enrollment and at least once annually. Infection was confirmed with HCV RNA. Risk factors for HCV were analyzed by proportional hazards regression, with hazard ratios (HRs) calculated in a multivariable model. RESULTS: Of 573 participants, 94% were MSM, with a median age of 26 years (range 18-70 years). The prevalence of HCV antibody was 9 of the 573, or 1.6% [95% confidence interval (CI): 0.7% to 3.0%]. In 1883 person-years (PY) of follow-up, 39 incident cases were identified (20.7 per 1000 PY, 95% CI: 15.1 to 28.3). All incident cases were identified from 2014 onward, and incidence rose from a range of 7.5-11.4 per 1000 PY between 2014 and 2016 to 44.8 per 1000 PY in 2018 (P = 0.001). Most cases (97.4%) were MSM and denied injecting drugs (37 of the 39, 94.5%). In multivariate analysis, methamphetamine use [adjusted HR 2.33 (95% CI: 1.13 to 4.8), P = 0.022], group sex [adjusted HR 2.54 (95% CI: 1.26 to 5.12), P = 0.009], and a history of positive Treponema pallidum hemagglutination or rapid plasma reagin [adjusted HR 2.43 (95% CI: 1.22 to 4.85), P = 0.012] were significantly associated with incident HCV. CONCLUSION: We report an HCV epidemic among this cohort of HIV-infected Bangkok-based MSM. Access to timely HCV diagnosis and treatment is needed to prevent morbidity and to decrease onward transmission.

Glioblastoma-Associated Microglia Reprogramming Is Mediated by Functional Transfer of Extracellular miR-21.

Gliomas are primary, diffusely infiltrating brain tumors. Microglia are innate immune cells in the CNS and make up a substantial portion of the tumor mass. Glioma cells shape their microenvironment, communicating with and reprogramming surrounding cells, resulting in enhanced angiogenesis, immune suppression, and remodeling of the extracellular matrix. Glioma cells communicate with microglia, in part by releasing extracellular vesicles (EVs). Mouse glioma cells stably expressing a palmitoylated GFP to label EVs were implanted intracranially into syngeneic miR-21-null mice. Here, we demonstrate functional delivery of miR-21, regulating specific downstream mRNA targets in microglia after uptake of tumor-derived EVs. These findings attest to EV-dependent microRNA delivery as studied in an in vivo-based model and provide insight into the reprograming of microglial cells by tumor cells to create a favorable microenvironment for cancer progression.