PD-1/PD-L1 checkpoint blockades have achieved significant progress in several kinds of tumours. Pembrolizumab, which targets PD-1, has been approved as a first-line treatment for advanced non-small cell lung cancer (NSCLC) patients with positive PD-L1 expression. However, PD-1/PD-L1 checkpoint blockades have not achieved breakthroughs in treating glioblastoma because glioblastoma has a low immunogenic response and an immunosuppressive microenvironment caused by the precise crosstalk between cytokines and immune cells. A phase III clinical trial, Checkmate 143, reported that nivolumab, which targets PD-1, did not demonstrate survival benefits compared with bavacizumab in recurrent glioblastoma patients. Thus, the combination of a PD-1/PD-L1 checkpoint blockade with RT, TMZ, antibodies targeting other inhibitory or stimulatory molecules, targeted therapy, and vaccines may be an appealing solution aimed at achieving optimal clinical benefit. There are many ongoing clinical trials exploring the efficacy of various approaches based on PD-1/PD-L1 checkpoint blockades in primary or recurrent glioblastoma patients. Many challenges need to be overcome, including the identification of discrepancies between different genomic subtypes in their response to PD-1/PD-L1 checkpoint blockades, the selection of PD-1/PD-L1 checkpoint blockades for primary versus recurrent glioblastoma, and the identification of the optimal combination and sequence of combination therapy. In this review, we describe the immunosuppressive molecular characteristics of the tumour microenvironment (TME), candidate biomarkers of PD-1/PD-L1 checkpoint blockades, ongoing clinical trials and challenges of PD-1/PD-L1 checkpoint blockades in glioblastoma.

Glioblastoma multiforme (GBM) is the most prevalent form of malignant brain tumor. Amlexanox, a novel compound, has been shown to have anti-cancer potential. In this study, the anti-tumoral effects and the underlying mechanisms of amlexanox were investigated. Amlexanox significantly suppressed proliferation and invasion and induced apoptosis in glioblastoma cells. Furthermore, we found that amlexanox altered the protein expression of the Hippo pathway by downregulating IKBKE. Our data indicates that IKBKE directly targets LATS1/2 and induces degradation of LATS1/2, thereby inhibiting the activity of the Hippo pathway. In vivo results further confirmed the tumor inhibitory effect of amlexanox via the downregulation of IKBKE, and amlexanox induced no apparent toxicity. Collectively, our studies suggest that amlexanox is a promising therapeutic agent for the treatment of GBM.

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Clenbuterol treatment for several weeks prevented up to one-third of the reduction in mineralization of femurs and tibias caused by sectioning of the sciatic nerve in young rats. The normalizing effect of clenbuterol on bone mineral content was directly proportional to similar alterations in muscle mass, which in turn could be abolished by ablation of the triceps surae or hindlimb unweighting and reduced by hypophysectomy. In contrast to the effects of inactivity, ovariectomy caused small reductions (2-4%) in bone density that were not affected by clenbuterol and were not accompanied by changes in ash weight. Together, our results suggest that the ability of beta 2-agonists to retard the loss in net muscle mass and enhance contractile tension can oppose net bone loss caused by denervation. Increases in contractile tension caused by beta 2-agonists may enhance the utility of exercise or electrical stimulation as countermeasures for the effects of scoliosis, prolonged bed rest, spinal cord injury, or weightlessness in space on bone mass.

IKBKE is increased in several types of cancers and is associated with tumour malignancy. In this study, we confirmed that IKBKE promoted glioma proliferation, migration and invasion in vitro. Then, we further discovered that IKBKE increased Yes-associated protein 1 (YAP1) and TEA domain family member 2 (TEAD2), two important Hippo pathway downstream factors, to induce an epithelial–mesenchymal transition (EMT), thus contributing to tumour invasion and metastasis. We also testified that YAP1 and TEAD2 promoted epithelial–mesenchymal transition (EMT) in malignant glioma. Furthermore, we constructed nude mouse subcutaneous and intracranial models to verify that IKBKE could attenuate U87-MG tumourigenicity in vivo. Collectively, our results suggest that IKBKE plays a pivotal role in regulating cell proliferation, invasion and epithelial–mesenchymal transition of malignant glioma cells in vitro and in vivo by impacting on the Hippo pathway. Therefore, targeting IKBKE may become a new strategy to treat malignant glioma.

Obesity has become a major health problem that has rapidly prevailed over the past several decades worldwide. Curcumin, a natural polyphenolic compound present in turmeric, has been shown to have a protective effect on against obesity and metabolic diseases. However, its underlying mechanism remains largely unknown. Here, we show that the administration of curcumin significantly prevents HFD-induced obesity and decreases the fat mass of the subcutaneous inguinal WAT (iWAT) and visceral epididymal WAT (eWAT) in mice. Mechanistically, curcumin inhibits adipogenesis by reducing the expression of AlkB homolog (ALKHB5), an m 6 A demethylase, which leads to higher m 6 A-modified TNF receptor-associated factor 4 (TRAF4) mRNA. TRAF4 mRNA with higher m 6 A level is recognized and bound by YTHDF1, leading to enhanced translation of TRAF4. TRAF4, acting as an E3 RING ubiquitin ligase, promotes degradation of adipocyte differentiation regulator PPARc by a ubiquitin-proteasome pathway thereby inhibiting adipogenesis. Thus, m 6 A-dependent TRAF4 expression upregulation by ALKBH5 and YTHDF1 contributes to curcumin-induced obesity prevention. Our findings provide mechanistic insights into how m 6 A is involved in the anti-obesity effect of curcumin.

Glioblastoma (GB) is the most common high-grade intracranial malignant tumor with highly malignant biological behavior and a high recurrence rate. Although anti-PD-1/PD-L1 antibodies have achieved significant survival benefits in several kinds of solid tumors, the phase III clinical trial Checkmate 143 demonstrated that nivolumab, which targets PD-1, did not achieve survival benefits compared with bevacizumab in recurrent glioblastoma (rGB) patients. Nevertheless, neoadjuvant anti-PD-1 therapy followed by surgery and adjuvant anti-PD-1 therapy could effectively activate local and systemic immune responses and significantly improve the OS of rGB patients. Furthermore, several studies have also confirmed the progress made in applying tumor-specific peptide vaccination or chimeric antigen receptor-T (CAR-T) cell therapy to treat rGB patients, and successes with antibodies targeting other inhibitory checkpoints or costimulatory molecules have also been reported. These successes inspired us to explore candidate combination treatments based on anti-PD-1/PD-L1 antibodies. However, effective predictive biomarkers for clinical efficacy are urgently needed to avoid economic waste and treatment delay. Attempts to prolong the CAR-T cell lifespan and increase T cell infiltration through engineering techniques are addressing the challenge of strengthening T cell function. In this review, we describe the immunosuppressive molecular characteristics of rGB; clinical trials exploring anti-PD-1/PD-L1 therapy, tumor-specific peptide vaccination, and CAR-T cell therapy; candidate combination strategies; and issues related to strengthening T cell function.

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