Project description:Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest types of cancer. A factor that contributes to the poor prognosis of the disease is the complex tumor microenvironment (TME). The PDAC TME is composed of excessive fibrosis and desmoplasia, which creates a harsh environment resulting in hypoxia and altered nutrient availability. To promote survival and proliferation in this environment, PDAC cells can reprogram glutamine (Gln) metabolism. Previous studies have demonstrated that PDAC cells use Gln to support proliferation and redox balance. However, earlier attempts to inhibit Gln metabolism using glutaminase inhibitors resulted in rapid metabolic reprogramming and ultimately therapeutic resistance. Here, we hypothesized that using a Gln analogue, such as 6-Diazo-5-oxo-L-norleucine (DON), could broadly target Gln metabolism in PDAC and prevent rapid adaptation. Indeed, DON treatment led to a significant decrease in PDAC proliferation in a dose-dependent manner, as well as a profound reduction of various metabolites involved in central carbon and nucleotide metabolism, suggesting that DON creates a metabolic crisis. In addition, we observed a significant decrease in tumor growth in various in vivo models (syngeneic, immunodeficient) using DRP-104 (sirpiglenastat), a novel pro-drug version of DON that was designed to circumvent DON associated GI toxicity and allow the therapeutic exploration of broad Gln antagonism. Mechanistically, we found that ERK signaling is increased as a compensatory mechanism through the increased activity of receptor tyrosine kinases (RTKs). Combinatorial treatment of DRP-104 and Trametinib (MEK1/2) inhibitor led to a significant increase in survival in a syngeneic model PDAC. Taken together, these pre-clinical results suggest that broadly targeting Gln metabolism could provide a new therapeutic avenue for PDAC and that the combination with an ERK signaling pathway inhibitor could further improve the therapeutic outcome.
Project description:Pancreatic ductal adenocarcinoma (PDA) is a highly lethal cancer with a long-term survival rate under 10%. Available cytotoxic chemotherapies have significant side effects, and only marginal therapeutic efficacy. FDA approved drugs currently used against PDA target DNA metabolism and DNA integrity. However, alternative metabolic targets beyond DNA may prove to be much more effective. PDA cells are forced to live within a particularly severe microenvironment characterized by relative hypovascularity, hypoxia, and nutrient deprivation. Thus, PDA cells must possess biochemical flexibility in order to adapt to austere conditions. A better understanding of the metabolic dependencies required by PDA to survive and thrive within a harsh metabolic milieu could reveal specific metabolic vulnerabilities. These molecular requirements can then be targeted therapeutically, and would likely be associated with a clinically significant therapeutic window since the normal tissue is so well-perfused with an abundant nutrient supply. Recent work has uncovered a number of promising therapeutic targets in the metabolic domain, and clinicians are already translating some of these discoveries to the clinic. In this review, we highlight mitochondria metabolism, non-canonical nutrient acquisition pathways (macropinocytosis and use of pancreatic stellate cell-derived alanine), and redox homeostasis as compelling therapeutic opportunities in the metabolic domain.
Project description:Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive disease with a 5-year survival rate of <10%. The tumour microenvironment (TME) of PDAC is characterized by excessive fibrosis and deposition of extracellular matrix, termed desmoplasia. This unique TME leads to high interstitial pressure, vascular collapse and low nutrient and oxygen diffusion. Together, these factors contribute to the unique biology and therapeutic resistance of this deadly tumour. To thrive in this hostile environment, PDAC cells adapt by using non-canonical metabolic pathways and rely on metabolic scavenging pathways such as autophagy and macropinocytosis. Here, we review the metabolic pathways that PDAC use to support their growth in the setting of an austere TME. Understanding how PDAC tumours rewire their metabolism and use scavenging pathways under environmental stressors might enable the identification of novel therapeutic approaches.
Project description:Cultured cancer cells frequently rely on the consumption of glutamine and its subsequent hydrolysis to glutamate by the mitochondrial enzyme glutaminase (GLS). However, this metabolic addiction can be lost in the tumor microenvironment (TME), rendering GLS inhibitors ineffective in the clinic. Here, we show that seemingly glutamine-addicted breast cancer cells ultimately adapt to chronic glutamine starvation, or targeted GLS inhibition, via the AMPK-mediated upregulation of the serine synthesis pathway (SSP). In this context, the key product of the SSP is not serine itself, but a-ketoglutarate (a-KG). Mechanistically, we find that the phylogenetically distinct transaminase phosphoserine aminotransferase 1 (PSAT1) has a unique capacity for sustained a-KG production when glutamate is severely depleted. Breast cancer cells with intrinsic or acquired resistance to glutamine starvation or GLS inhibition are highly dependent on SSP-supplied a-KG. Accordingly, pharmacological disruption of the SSP prevents adaptation to glutamine blockade, yielding a potent drug synergism that abolishes breast tumor growth in vivo. These findings highlight how metabolic redundancy can be context dependent, with the catalytic properties of different metabolic enzymes that act on the same substrate determining which pathways can support tumor growth in a particular nutrient environment. This in turn has practical consequences for therapies targeting cancer metabolism.
Project description:Glutamine metabolism in the tumor microenvironment is emerging as a critical regulator of immune-mediated anti-tumor responses. We report potent tumor growth inhibition by the glutamine antagonist prodrug JHU083 in urologic tumors by JHU083-reprogrammed tumor-associated macrophages (TAMs) and tumor-infiltrating monocytes (TIMs). Using orthogonal approaches, we show that JHU083-mediated glutamine antagonism in the tumor microenvironment induces TNF, inflammatory, and mTORC1 signaling in different intra-tumoral TAM clusters. Additionally, we report that JHU083 increases proliferation in tissue-resident macrophages intratumorally and in different TAM sub-clusters. Functionally, we report that JHU083-reprogrammed TAMs have increased tumor cell phagocytosis and diminished pro-angiogenic capacities. In vivo inhibition of glutamine consumption in TAMs results in increased glycolysis, broken TCA cycle, and disruption in purine metabolism. Although the effect of glutamine antagonism was less profound on tumor-infiltrating T cells for their anti-tumor activity, it promoted a stem cell-like phenotype in CD8+ T cells and decreased the CD4+ Treg abundance. Additionally, we report that JHU083 causes a global shutdown in glutamine utilizing metabolic pathways in tumor cells, leading to reduced HIF-1, c-MYC phosphorylation, and induction of tumor cell apoptosis, all key anti-tumoral features.
Project description:Purpose of reviewIn an attempt to identify potential new therapeutic targets, efforts to describe the metabolic features unique to cancer cells are increasingly being reported. Although current standard of care regimens for several pediatric malignancies incorporate agents that target tumor metabolism, these drugs have been part of the therapeutic landscape for decades. More recent research has focused on the identification and targeting of new metabolic vulnerabilities in pediatric cancers. The purpose of this review is to describe the most recent translational findings in the metabolic targeting of pediatric malignancies.Recent findingsAcross multiple pediatric cancer types, dependencies on a number of key metabolic pathways have emerged through study of patient tissue samples and preclinical modeling. Among the potentially targetable vulnerabilities are glucose metabolism via glycolysis, oxidative phosphorylation, amino acid and polyamine metabolism, and NAD metabolism. Although few agents have yet to move forward into clinical trials for pediatric cancer patients, the robust and promising preclinical data that have been generated suggest that future clinical trials should rationally test metabolically targeted agents for relevant disease populations.SummaryRecent advances in our understanding of the metabolic dependencies of pediatric cancers represent a source of potential new therapeutic opportunities for these diseases.