Although low risk localised prostate cancer has an excellent prognosis owing to effective treatments, such as surgery, radiation, cryosurgery and hormone therapy, metastatic prostate cancer remains incurable. Existing therapeutic regimens prolong life; however, they are beset by problems of resistance, resulting in poor outcomes. Treatment resistance arises primarily from tumour heterogeneity, altered genetic signatures and metabolic reprogramming, all of which enable the tumour to serially adapt to drugs during the course of treatment. In this review, we focus on alterations in the metabolism of prostate cancer, including genetic signatures and molecular pathways associated with metabolic reprogramming. Advances in our understanding of prostate cancer metabolism might help to explain many of the adaptive responses that are induced by therapy, which might, in turn, lead to the attainment of more durable therapeutic responses.

Glioblastoma is a highly lethal adult brain tumor with no effective treatments. In this review, we discuss the potential to target cholesterol metabolism as a new strategy for treating glioblastomas. Twenty percent of cholesterol in the body is in the brain, yet the brain is unique among organs in that it has no access to dietary cholesterol and must synthesize it de novo. This suggests that therapies targeting cholesterol synthesis in brain tumors might render their effects without compromising cell viability in other organs. We will describe cholesterol synthesis and homeostatic feedback pathways in normal brain and brain tumors, as well as various strategies for targeting these pathways for therapeutic intervention.

Cholesterol is a critical component of membranes and a precursor for hormones and other signaling molecules. Previously, we showed that unlike astrocytes, glioblastoma cells do not downregulate cholesterol synthesis when plated at high density. In this report, we show that high cell density induces ABCA1 expression in glioblastoma cells, enabling them to get rid of excess cholesterol generated by an activated cholesterol biosynthesis pathway. Because oxysterols are agonists for Liver X Receptors (LXRs), we investigated whether increased cholesterol activates LXRs to maintain cholesterol homeostasis in highly-dense glioblastoma cells. We observed that dense cells had increased oxysterols, which activated LXRβ to upregulate ABCA1. Cells with CRISPR-mediated knockdown of LXRβ, but not ABCA1, had decreased cell cycle progression and cell survival, and decreased feedback repression of the mevalonate pathway in densely-plated glioma cells. LXRβ gene expression poorly correlates with ABCA1 in glioblastoma patients, and expression of each gene correlates with poor patient prognosis in different prognostic subtypes. Finally, gene expression and lipidomics analyses cells revealed that LXRβ regulates the expression of immune response gene sets and lipids known to be involved in immune modulation. Thus, therapeutic targeting of LXRβ in glioblastoma might be effective through diverse mechanisms.

Advanced prostate cancer is treated with androgen receptor (AR) signaling inhibitors, which are initially effective, but most patients eventually develop resistance and progress to castrate-resistant prostate cancer (CRPC). Loss of RB1 in CRPC tumors is correlated with rapid progression and poor patient survival and, in combination with TP53 loss, predisposes patients to the development of transitional neuroendocrine prostate cancer (NEPC). Although progressive CRPC is clinically associated with higher 18FDG-PET SUVmax values, it is unknown whether inactivation of RB1 and/or TP53 is a driver of increased glucose import. Using a cohort of patient-derived xenograft (PDX)-derived CRPC organoids, we found that NEPC could not be conclusively distinguished from adenocarcinoma by 18FDG uptake alone, and PSMA protein levels did not correlate with cancer phenotype or 18FDG uptake. Castration-resistant models showed higher 18FDG uptake, but lower pyruvate-to-lactate conversion compared to their castration-sensitive counterparts. In parallel studies using castration-sensitive prostate cancer models, RB1/TP53 knockdown did not affect 18FDG uptake, but increased basal respiration and glycolytic activity, with combined depletion leading to glucose diversion into glycogenesis. These metabolic changes were reflected in increased lactate dehydrogenase flux detected by 13C-hyperpolarized magnetic resonance spectroscopy upon RB1 loss, but not in 18FDG uptake. The metabolic heterogeneity revealed here suggests that a multimodal molecular imaging approach can improve tumor characterization, potentially leading to a better prognosis in cancer treatment.

MBNL1 binds the HIF-1α 3'UTR to promote rapid mRNA decay, thereby limiting HIF-1 activity and hypoxia-induced stemness in glioblastoma. Using patient-derived glioma stem cells, we show that MBNL1 loss stabilizes HIF-1α mRNA and increases HIF-1α protein, HRE reporter activity, and target gene expression under hypoxia; MBNL1 knockout also prolongs target gene expression after reoxygenation, indicating enhanced hypoxia "memory." MBNL1 depletion markedly elevates stemness markers (KLF4, SOX2, GLI1) and clonogenic growth, and re-expression of MBNL1 reverses these effects. These results identify a post-transcriptional MBNL1-HIF1α axis that controls hypoxia signaling and stemness, with implications for GBM therapy.