[18F]-FDHT PET/CT as a tool for imaging androgen receptor expression in high-grade glioma

Intracranial Assessment of Androgen Receptor Antagonists in Mice Bearing Human Glioblastoma Implants

The median survival time of patients with an aggressive brain tumor, glioblastoma, is still poor due to ineffective treatment. The discovery of androgen receptor (AR) expression in 56% of cases offers a potential breakthrough. AR antagonists, including bicalutamide and enzalutamide, induce dose-dependent cell death in glioblastoma and glioblastoma-initiating cell lines (GIC). Oral enzalutamide at 20 mg/kg reduces subcutaneous human glioblastoma xenografts by 72% (p = 0.0027). We aimed to further investigate the efficacy of AR antagonists in intracranial models of human glioblastoma. In U87MG intracranial models, nude mice administered Xtandi (enzalutamide) at 20 mg/kg and 50 mg/kg demonstrated a significant improvement in survival compared to the control group (p = 0.24 and p < 0.001, respectively), confirming a dose-response relationship. Additionally, we developed a newly reformulated version of bicalutamide, named "soluble bicalutamide (Bic-sol)", with a remarkable 1000-fold increase in solubility. This reformulation significantly enhanced bicalutamide levels within brain tissue, reaching 176% of the control formulation's area under the curve. In the U87MG intracranial model, both 2 mg/kg and 4 mg/kg of Bic-sol exhibited significant efficacy compared to the vehicle-treated group (p = 0.0177 and p = 0.00364, respectively). Furthermore, combination therapy with 8 mg/kg Bic-sol and Temozolomide (TMZ) demonstrated superior efficacy compared to either Bic-sol or TMZ as monotherapies (p = 0.00706 and p = 0.0184, respectively). In the ZH-161 GIC mouse model, the group treated with 8 mg/kg Bic-sol as monotherapy had a significantly longer lifespan than the groups treated with TMZ or the vehicle (p < 0.001). Our study demonstrated the efficacy of androgen receptor antagonists in extending the lifespan of mice with intracranial human glioblastoma, suggesting a promising approach to enhance patient outcomes in the fight against this challenging disease.

From signalling pathways to targeted therapies: unravelling glioblastoma's secrets and harnessing two decades of progress

Glioblastoma, a rare, and highly lethal form of brain cancer, poses significant challenges in terms of therapeutic resistance, and poor survival rates for both adult and paediatric patients alike. Despite advancements in brain cancer research driven by a technological revolution, translating our understanding of glioblastoma pathogenesis into improved clinical outcomes remains a critical unmet need. This review emphasises the intricate role of receptor tyrosine kinase signalling pathways, epigenetic mechanisms, and metabolic functions in glioblastoma tumourigenesis and therapeutic resistance. We also discuss the extensive efforts over the past two decades that have explored targeted therapies against these pathways. Emerging therapeutic approaches, such as antibody-toxin conjugates or CAR T cell therapies, offer potential by specifically targeting proteins on the glioblastoma cell surface. Combination strategies incorporating protein-targeted therapy and immune-based therapies demonstrate great promise for future clinical research. Moreover, gaining insights into the role of cell-of-origin in glioblastoma treatment response holds the potential to advance precision medicine approaches. Addressing these challenges is crucial to improving outcomes for glioblastoma patients and moving towards more effective precision therapies.

Androgen Receptor Imaging in the Management of Hormone-Dependent Cancers with Emphasis on Prostate Cancer

Prostate cancer is dependent on the action of steroid hormones on the receptors. Endocrine therapy inhibits hormone production or blocks the receptors, thus providing clinical benefit to many, but not all, oncological patients. It is difficult to predict which patient will benefit from endocrine therapy and which will not. Positron Emission Tomography (PET) imaging of androgen receptors (AR) may provide functional information on the likelihood of endocrine therapy response in individual patients. In this article, we review the utility of [¹⁸F]FDHT-PET imaging in prostate, breast, and other hormone-dependent cancers expressing AR. The methodologies, development, and new possibilities are discussed as well.

Androgen Receptor Expression in the Various Regions of Resected Glioblastoma Multiforme Tumors and in an In Vitro Model

Glioblastoma multiforme (GBM) is a malignant glioma, difficult to detect and with the lowest survival rates among gliomas. Its greater incidence among men and its higher survival rate among premenopausal women suggest that it may be associated with the levels of androgens. As androgens stimulate the androgen receptor (AR), which acts as a transcription factor, the aim of this study was the investigate the role of AR in the progression of GBM. The study was conducted on tissues collected from three regions of GBM tumors (tumor core, enhancing tumor region, and peritumoral area). In addition, an in vitro experiment was conducted on U-87 cells under various culture conditions (necrotic, hypoxic, and nutrient-deficient), mimicking the conditions in a tumor. In both of the models, androgen receptor expression was determined at the gene and protein levels, and the results were confirmed by confocal microscopy and immunohistochemistry. AR mRNA expression was higher under nutrient-deficient conditions and lower under hypoxic conditions in vitro. However, there were no differences in AR protein expression. No differences in AR mRNA expression were observed between the tested tumor structures taken from patients. No differences in AR mRNA expression were observed between the men and women. However, AR protein expression in tumors resected from patients was higher in the enhancing tumor region and in the peritumoral area than in the tumor core. In women, higher AR expression was observed in the peritumoral area than in the tumor core. AR expression in GBM tumors did not differ significantly between men and women, which suggests that the higher incidence of GBM in men is not associated with AR expression. In the group consisting of men and women, AR expression varied between the regions of the tumor: AR expression was higher in the enhancing tumor region and in the peritumoral area than in the tumor core, showing a dependence on tumor conditions (hypoxia and insufficient nutrient supply).

Exploration of CT Images Based on the BN-U-net-W Network Segmentation Algorithm in Glioma Surgery

This study aimed to explore the application value of computed tomography (CT) imaging features based on the deep learning batch normalization (batch normalization, BN) U-net-W network image segmentation algorithm in evaluating and diagnosing glioma surgery. 72 patients with glioma who were admitted to hospital were selected as the research subjects. They were divided into a low-grade group (grades I-II, N = 27 cases) and high-grade group (grades III-IV, N = 45 cases) according to postoperative pathological examination results. The CT perfusion imaging (CTPI) images of patients were processed by using the deep learning-based BN-U-net-W network image segmentation algorithm. The application value of the algorithm was comprehensively evaluated by comparing the average Dice coefficient, average recall rate, and average precision of the BN-U-net-W network image segmentation algorithm with the U-net and BN-U-net network algorithms. The results showed that the Dice coefficient, recall, and precision of the BN-U-net-W network were 86.31%, 88.43%, and 87.63% respectively, which were higher than those of the U-net and BN-U-net networks, and the differences were statistically significant (P < 0.05). Cerebral blood flow (CBF), cerebral blood volume (CBV), and capillary permeability (PMB) in the glioma area were 56.85 mL/(min·100 g), 18.03 mL/(min·100 g), and 8.57 mL/100 g, respectively, which were significantly higher than those of normal brain tissue, showing statistically significant differences (P < 0.05). The mean transit time (MTT) difference between the two was not statistically significant (P > 0.05). The receiver operating characteristic (ROC) curves of CBF, CBV, and PMB in CTPI parameters of glioma had area under the curve (AUC) of 0.685, 0.724, and 0.921, respectively. PMB parameters were significantly higher than those of CBF and CVB, and the differences were statistically obvious (P < 0.05). It showed that the BN-U-net-W network model had a better image segmentation effect, and CBF, CBV, and PMB showed better sensitivity in diagnosing glioma tissue and normal brain tissue and high-grade and low-grade gliomas, among which PBM showed the highest predictability.

Androgen Receptor Activation in Glioblastoma Can Be Achieved by Ligand-Independent Signaling through EGFR-A Potential Therapeutic Target

Androgen receptor (AR) is a ligand-mediated transcription factor that belongs to the superfamily of steroid receptors. AR is overexpressed in most glioblastomas and is a potential therapeutic target. In prostate and breast cancers, AR activation can be achieved also by a ligand-independent signaling through receptor tyrosine kinases such as epidermal growth factor receptor (EGFR). Considering its major role in glioblastoma, we explored whether EGFR is involved in AR signaling in this tumor. Analysis of mRNA expression in 28 glioblastoma samples with quantitative real-time reverse-transcription polymerase chain reaction revealed a positive and significant correlation between AR and EGFR mRNA expression levels (R = 0.47, p = 0.0092), which was validated by The Cancer Genome Atlas dataset (n = 671) analysis (R = 0.3, p = 0.00006). Using Western blotting and immunofluorescence staining, we showed that the transduced overexpression of EGFR or its variant EGFRvIII in the U87MG cells induced AR protein overexpression and nuclear translocation and Protein kinase B (AKT) S473 and AR S210/213 phosphorylation. The EGFR kinase inhibitor afatinib and the AKT inhibitor MK2206 reduced AR nuclear translocation. Afatinib diminished AKT phosphorylation at 30 min and 6 h in the EGFR- and EGFRvIII-overexpressing cells, respectively, and decreased AR phosphorylation in EGFR-overexpressing cells at 4 h. Afatinib or MK2206 combination therapy with the AR antagonist enzalutamide in the EGFR and EGFRvIII-overexpressing cells had synergistic efficacy. Our findings suggest that EGFR signaling is involved in AR activation in glioblastoma and buttresses the concept of combining an EGFR signaling inhibitor with AR antagonists as a potential glioblastoma treatment.