SUMMARY Activated T cells differentiate into functional subsets with distinct metabolic programs. Glutaminase (GLS) converts glutamine to glutamate to support the tricarboxylic acid cycle and redox and epigenetic reactions. Here, we identify a key role for GLS in T cell activation and specification. Though GLS deficiency diminished initial T cell activation and proliferation and impaired differentiation of Th17 cells, loss of GLS also increased Tbet to promote differentiation and effector function of CD4 Th1 and CD8 CTL cells. This was associated with altered chromatin accessibility and gene expression, including decreased PIK3IP1 in Th1 cells that sensitized to IL-2-mediated mTORC1 signaling. In vivo, GLS null T cells failed to drive Th17-inflammatory diseases, and Th1 cells had initially elevated function but exhausted over time. Transient GLS inhibition, however, led to increased Th1 and CTL T cell numbers. Glutamine metabolism thus has distinct roles to promote Th17 but constrain Th1 and CTL effector cell differentiation.

Summary Most patients with advanced triple-negative breast cancer (TNBC) develop drug resistance. MYC and MCL1 are frequently co-amplified in drug-resistant TNBC after neoadjuvant chemotherapy. Herein, we demonstrate that MYC and MCL1 cooperate in the maintenance of chemotherapy-resistant cancer stem cells (CSCs) in TNBC. MYC and MCL1 increased mitochondrial oxidative phosphorylation (mtOXPHOS) and the generation of reactive oxygen species (ROS), processes involved in maintenance of CSCs. A mutant of MCL1 that cannot localize in mitochondria reduced mtOXPHOS, ROS levels and drug-resistant CSCs without affecting the anti-apoptotic function of MCL1. Increased levels of ROS, a by-product of activated mtOXPHOS, led to the accumulation of HIF-1α. Pharmacological inhibition of HIF-1α attenuated CSC enrichment and tumor initiation in vivo. These data suggest that 1) MYC and MCL1 confer resistance to chemotherapy by expanding CSCs via mtOXPHOS; and 2) targeting mitochondrial respiration and HIF-1α may reverse chemotherapy resistance in TNBC.

provided expertise to develop 18 F nutrient uptake assays. F.X. and M.N.T injected and handled mice for 18 F nutrient uptake assays, and performed and provided expertise for PET imaging and autoradiography. T.H. and W.D.M. performed and provided expertise for intrarenal Renca experiments. R.W.J. and V.T.M generated and provided expertise for PyMT GEMM tumors. R.E.B and C.S.W. generated and provided expertise for AOM/DSS CRC tumors. B.I.R. R.T.O. and M.H.W. generated the pTZeo-EL-thy1.1 transposon construct and engineered MC38 cells using this transposon system. B.I.R, M.Z.M, and A.S. performed in vivo 2NBDG studies. J.E.B. provided expertise in characterizing TAM. A.R.P provided expertise in flow sorting for mRNA transcript analysis. B.I.R. and M.Z.M performed extracellular flux and mRNA transcript experiments. F.M.M. and E.F.M performed and provided expertise in cell staining for light microscopy. E.F.M performed light microscopy and pathologic examination of MC38 tumors. A.A (VU) conducted transcriptomic analysis. B.I.R and M.Z.M. analyzed all data generated in this study. J.C.R. and W.K.R. obtained funding for this study.Data Availability Statement (DAS) All data will be made available upon reasonable request to JCR/WKR. Tumor mRNA transcript data that support the findings of this study have been deposited in Gene Expression Omnibus (GEO) under accession GSE165223. These data are also found in Supplementary Information Table 4. Code Availability Statement (CAS)The code used to support tumor mRNA transcript analysis has been previously published (see methods references) and will be made available upon request to JCR/WKR.

Renal cell carcinoma (RCC) comprises a diverse group of malignancies arising from the nephron. The most prevalent type, clear cell renal cell carcinoma (ccRCC), is characterized by genetic mutations in factors governing the hypoxia signaling pathway, resulting in metabolic dysregulation, heightened angiogenesis, intratumoral heterogeneity, and deleterious tumor microenvironmental (TME) crosstalk. Identification of specific genetic variances has led to therapeutic innovation and improved survival for patients with ccRCC. Current barriers to effective long-term therapeutic success highlight the need for continued drug development using improved modeling systems. ccRCC preclinical models can be grouped into three broad categories: cell line, mouse, and 3D models. Yet, the breadth of important unanswered questions in ccRCC research far exceeds the accessibility of model systems capable of carrying them out. Accordingly, we review the strengths, weaknesses, and therapeutic implications of each model system that are relied upon today.