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Lineage plasticity has long been documented in both small cell lung cancer (SCLC) and neuroblastoma, two clinically distinct neuroendocrine (NE) cancers. In this study, we quantified the NE features of cancer as NE scores and performed a systematic comparison of SCLC and neuroblastoma. We found neuroblastoma and SCLC cell lines have highly similar molecular profiles and shared therapeutic sensitivity. In addition, NE heterogeneity was observed at both the inter- and intra-cell line levels. Surprisingly, we did not find a significant association between NE scores and overall survival in SCLC or neuroblastoma. We described many shared and unique NE score–associated features between SCLC and neuroblastoma, including dysregulation of Myc oncogenes, alterations in protein expression, metabolism, drug resistance, and selective gene dependencies. Implications: Our work establishes a reference for molecular changes and vulnerabilities associated with NE to non-NE transdifferentiation through mutual validation of SCLC and neuroblastoma samples.

Mutations in IDH genes occur frequently in acute myeloid leukemia (AML) and other human cancers to generate the oncometabolite R-2HG. Allosteric inhibition of mutant IDH suppresses R-2HG production in a subset of patients with AML; however, acquired resistance emerges as a new challenge, and the underlying mechanisms remain incompletely understood. Here we establish isogenic leukemia cells containing common IDH oncogenic mutations by CRISPR base editing. By mutational scanning of IDH single amino acid variants in base-edited cells, we describe a repertoire of IDH second-site mutations responsible for therapy resistance through disabling uncompetitive enzyme inhibition. Recurrent mutations at NADPH binding sites within IDH heterodimers act in cis or trans to prevent the formation of stable enzyme–inhibitor complexes, restore R-2HG production in the presence of inhibitors, and drive therapy resistance in IDH-mutant AML cells and patients. We therefore uncover a new class of pathogenic mutations and mechanisms for acquired resistance to targeted cancer therapies. Significance: Comprehensive scanning of IDH single amino acid variants in base-edited leukemia cells uncovers recurrent mutations conferring resistance to IDH inhibition through disabling NADPH-dependent uncompetitive inhibition. Together with targeted sequencing, structural, and functional studies, we identify a new class of pathogenic mutations and mechanisms for acquired resistance to IDH-targeting cancer therapies. This article is highlighted in the In This Issue feature, p. 1

Controlling for MYCN amplification status increases the statistical significance of NE score vs. MYCN expression association.

Lineage plasticity has long been documented in both small cell lung cancer (SCLC) and neuroblastoma, two clinically distinct neuroendocrine (NE) cancers. In this study, we quantified the NE features of cancer as NE scores and performed a systematic comparison of SCLC and neuroblastoma. We found neuroblastoma and SCLC cell lines have highly similar molecular profiles and shared therapeutic sensitivity. In addition, NE heterogeneity was observed at both the inter- and intra-cell line levels. Surprisingly, we did not find a significant association between NE scores and overall survival in SCLC or neuroblastoma. We described many shared and unique NE score–associated features between SCLC and neuroblastoma, including dysregulation of Myc oncogenes, alterations in protein expression, metabolism, drug resistance, and selective gene dependencies.Implications:Our work establishes a reference for molecular changes and vulnerabilities associated with NE to non-NE transdifferentiation through mutual validation of SCLC and neuroblastoma samples.

SUMMARYCancer cells reprogram their metabolism to support cell growth and proliferation in harsh environments. While many studies have documented the importance of mitochondrial oxidative phosphorylation (OXPHOS) in tumor growth, some cancer cells experience conditions of reduced OXPHOS in vivo and induce alternative metabolic pathways to compensate. To assess how human cells respond to mitochondrial dysfunction, we performed metabolomics in fibroblasts and plasma from patients with inborn errors of mitochondrial metabolism, and in cancer cells subjected to inhibition of the electron transport chain (ETC). All these analyses revealed extensive perturbations in purine-related metabolites; in non-small cell lung cancer (NSCLC) cells, ETC blockade led to purine metabolite accumulation arising from a reduced cytosolic NAD+/NADH ratio (NADH reductive stress). Stable isotope tracing demonstrated that ETC deficiency suppressed de novo purine nucleotide synthesis while enhancing purine salvage. Analysis of NSCLC patients infused with [U-13C]glucose revealed that tumors with markers of low oxidative mitochondrial metabolism exhibited high expression of the purine salvage enzyme HPRT1 and abundant levels of the HPRT1 product inosine monophosphate (IMP). ETC blockade also induced production of ribose-5’ phosphate (R5P) by the pentose phosphate pathway (PPP) and import of purine nucleobases. Blocking either HPRT1 or nucleoside transporters sensitized cancer cells to ETC inhibition, and overexpressing nucleoside transporters was sufficient to drive growth of NSCLC xenografts. Collectively, this study mechanistically delineates how cells compensate for suppressed purine metabolism in response to ETC blockade, and uncovers a new metabolic vulnerability in tumors experiencing NADH excess.

Figs. S1-S14

In order to identify new cancer-associated metabolites that may be useful for early detection of lung cancer, we performed a global metabolite profiling of a non–small cell lung cancer (NSCLC) line and immortalized normal lung epithelial cells from the same patient. Among several metabolites with significant cancer/normal differences, we identified a unique metabolic compound, N-acetylaspartate (NAA), in cancer cells—undetectable in normal lung epithelium. NAA's cancer-specific detection was validated in additional cancer and control lung cells as well as selected NSCLC patient tumors and control tissues. NAA's cancer specificity was further supported in our analysis of NAA synthetase (gene symbol: NAT8L) gene expression levels in The Cancer Genome Atlas: elevated NAT8L expression in approximately 40% of adenocarcinoma and squamous cell carcinoma cases (N = 577), with minimal expression in all nonmalignant lung tissues (N = 74). We then showed that NAT8L is functionally involved in NAA production of NSCLC cells through siRNA-mediated suppression of NAT8L, which caused selective reduction of intracellular and secreted NAA. Our cell culture experiments also indicated that NAA biosynthesis in NSCLC cells depends on glutamine availability. For preliminary evaluation of NAA's clinical potential as a circulating biomarker, we developed a sensitive NAA blood assay and found that NAA blood levels were elevated in 46% of NSCLC patients (N = 13) in comparison with age-matched healthy controls (N = 21) among individuals aged 55 years or younger. Taken together, these results indicate that NAA is produced specifically in NSCLC tumors through NAT8L overexpression, and its extracellular secretion can be detected in blood. Cancer Prev Res; 9(1); 43–52. ©2015 AACR.

Supplementary Figure S1. Identical exact masses of MMG and MMG-L from HCC4017. Supplementary Figure S2. Confirmation of MMG-L as NAA with LC-MS/MS. Supplementary Figure S3. Confirmation of MMG-L as NAA by comparing its GC MS data (top panel) with that of standard NAA (bottom panel). Supplementary Figure S4. Gene expression levels of NAT8L, the key enzyme for NAA biosynthesis, in 16 squamous cell carcinoma (SC) lung tumors as compared with patient-matched non-malignant lung tissues. Supplementary Figure S5. Gene expression levels of NAT8L in tumors and non-tumor regions of lung cancer patients. Supplementary Figure S6. Western Blot analysis of NAT8L in NSCLC cell lines. Supplementary Figure S7. Dependence of NAA biosynthesis on NAT8L enzyme in HCC4017 lung cancer cells. Supplementary Figure S8. Comparison of intracellular levels of NAA with those of glutamine, glucose, or NAT8L proteins in NSCLC cell lines. Supplementary Figure S9. Comparison of NAAG and NAA levels in HCC4017 cells using LC-MS. Supplementary Figure S10. Standard curve for NAA blood concentrations vs normalized NAA intensities. Supplementary Figure S11. Age-dependent variation of NAA blood levels in control human samples.

Table S3 shows sequences of primers and shRNAs

Supplementary Figures and Legends combined file contains 14 supplementary figures

Clinical information of blood plasma samples from lung cancer patients and control individuals.

Table S1: Clinical Characteristics of Melanoma Brain Metastases, Extracranial Metastases, and Primary Tumors. Tab 1. Clinical data for the MBMs and ECMs from melanoma patients utilized in this manuscript. Tab 2. Clinical data for primary melanomas from melanoma patients utilized in this manuscript.

There is a critical need to improve our understanding of the pathogenesis of melanoma brain metastases (MBM). Thus, we performed RNA sequencing on 88 resected MBMs and 42 patient-matched extracranial metastases; tumors with sufficient tissue also underwent whole-exome sequencing, T-cell receptor sequencing, and IHC. MBMs demonstrated heterogeneity of immune infiltrates that correlated with prior radiation and post-craniotomy survival. Comparison with patient-matched extracranial metastases identified significant immunosuppression and enrichment of oxidative phosphorylation (OXPHOS) in MBMs. Gene-expression analysis of intracranial and subcutaneous xenografts, and a spontaneous MBM model, confirmed increased OXPHOS gene expression in MBMs, which was also detected by direct metabolite profiling and [U-13C]-glucose tracing in vivo. IACS-010759, an OXPHOS inhibitor currently in early-phase clinical trials, improved survival of mice bearing MAPK inhibitor–resistant intracranial melanoma xenografts and inhibited MBM formation in the spontaneous MBM model. The results provide new insights into the pathogenesis and therapeutic resistance of MBMs.Significance:Improving our understanding of the pathogenesis of MBMs will facilitate the rational development and prioritization of new therapeutic strategies. This study reports the most comprehensive molecular profiling of patient-matched MBMs and extracranial metastases to date. The data provide new insights into MBM biology and therapeutic resistance.See related commentary by Egelston and Margolin, p. 581.This article is highlighted in the In This Issue feature, p. 565

Supplementary Figure S1. PHGDH is highly expressed in Ewing sarcoma cell lines; Supplementary Figure S2. Measurement of PHGDH protein expression. Immunoblot analysis of PHGDH in the specified cell lines expressing lentiviral control shRNA (shControl) or no shRNA (Parental); Supplementary Figure S3. PHGDH knockdown and ES proliferation in vitro; Supplementary Figure S4. Effect of GNE-618 on ES cellular proliferation; Supplementary Figure S5. Dose-effect Curves for GNE-618 and NCT-503; Supplementary Figure S6. Mouse body weight is unaffected by inhibitor treatments; Supplementary Figure S7. EWS-FLI1 is important for sarcoma cellular proliferation in the absence of serine; Supplementary Figure S8. Mouse body weight is unaffected by serine/glycine deficient diet

Extended Experimental Methods

Supplemental Figure S1. Integrative Analysis of Functional Genomics and Copy Number Variation in Melanoma Cells and Tissues, Supplemental Figure S2. Elastic Net Derived Biomarker Results for Melanoma Survival Genes and Detection of These Biomarkers in TCGA SKCM, Supplemental Figure S3. The SOX10 Regulatory Network Supporting Cell Autonomous Melanoma Cell Growth and Survival, Supplemental Figure S4. SOX10 Addiction Specifies Sensitivity of BRAF Mutant Melanomas to BRAF and MEK Inhibitors In Vitro, Related to Figure 1, Supplemental Figure S5. SOX10 Addiction Specifies Sensitivity of BRAF Mutant Melanomas to BRAF and MEK Inhibitors In Patients, Related to Figure 2, Supplemental Figure S6. Bicluster of melanoma cell lines and chemical compounds in McDermott/Benes GDSC dataset, Related to Figure 3, Supplemental Figure S7. Nomination of TBK1 as a Therapeutic Target for Drug-Resistant Melanoma, Related to Figure 3, Supplemental Figure S8. TBK1/IKKε-Addiction is Conserved In Vivo, Related to Figure 4, Supplemental Figure S9. TBK1/IKKε-Addiction Corresponds to a Cell Autonomous Innate Immune Melanoma Subtype, Related to Figure 5, Supplemental Figure S10. TBK1/IKKε Activate AKT and YAP to Support Survival of the Cell-autonomous Immune Melanoma Subtype, Related to Figure 6, Supplemental Figure S11. 13C glucose and 13C glutamine metabolism at 30m and 2h, Related to Figure 7 and Supplemental Fig. S7, Supplemental Figure S12. Distinct Epigenetic Cell Fate Programs Specify TBK1/IKKε Addiction, Related to Figure 7.

Supplemental Methods; Supplemental References

Epigenetic gene regulation and metabolism are highly intertwined, yet little is known about whether altered epigenetics influence cellular metabolism during cancer progression. Here, we show that EZH2 and NRASG12D mutations cooperatively induce progression of myeloproliferative neoplasms to highly penetrant, transplantable, and lethal myeloid leukemias in mice. EZH1, an EZH2 homolog, is indispensable for EZH2-deficient leukemia-initiating cells and constitutes an epigenetic vulnerability. BCAT1, which catalyzes the reversible transamination of branched-chain amino acids (BCAA), is repressed by EZH2 in normal hematopoiesis and aberrantly activated in EZH2-deficient myeloid neoplasms in mice and humans. BCAT1 reactivation cooperates with NRASG12D to sustain intracellular BCAA pools, resulting in enhanced mTOR signaling in EZH2-deficient leukemia cells. Genetic and pharmacologic inhibition of BCAT1 selectively impairs EZH2-deficient leukemia-initiating cells and constitutes a metabolic vulnerability. Hence, epigenetic alterations rewire intracellular metabolism during leukemic transformation, causing epigenetic and metabolic vulnerabilities in cancer-initiating cells.Significance:EZH2 inactivation and oncogenic NRAS cooperate to induce leukemic transformation of myeloproliferative neoplasms by activating BCAT1 to enhance BCAA metabolism and mTOR signaling. We uncover a mechanism by which epigenetic alterations rewire metabolism during cancer progression, causing epigenetic and metabolic liabilities in cancer-initiating cells that may be exploited as potential therapeutics.See related commentary by Li and Melnick, p. 1158.This article is highlighted in the In This Issue feature, p. 1143

Supplementary Table S1. Evaluation of drug combinations in TC32 and TC71 Ewing sarcoma cells; Supplementary Table S2. Evaluation of drug combinations in EW8 Ewing sarcoma cells.

Chemical identification of MMG-L as N-acetylaspartate (NAA). Supplementary Methods Supplementary Figure Legends

Supplementary Table 1: Baseline characteristics for patients included in the integrated gene set enrichment analysis (Figure 2-3) by cohort; Supplementary Table 6: The most frequent somatic alterations (alts) in patients with regionally metastatic melanoma by body mass index from The Cancer Genome Atlas cohort; Supplemental Table 7: Integrated gene set enrichment analysis for pathways associated with fatty acid metabolism by body mass index; Supplemental Table 8: Gene expression of selected genes of interest involved in fatty acid metabolism.

Integrated gene set enrichment analysis by body mass index (BMI) with correction for S phase. This figure presents a dotplot of genes differentially up- or downregulated in OW/OB patients versus NL BMI patients. Red indicates upregulation in OW/OB verse NL. The far left column is all patients, and then, an analysis controlling for sex, cohort, and tissue site is shown in the 3 columns to the right.

Differential gene expression analysis for each subgroup.

Purpose:Overweight/obese (OW/OB) patients with metastatic melanoma unexpectedly have improved outcomes with immune checkpoint inhibitors (ICI) and BRAF-targeted therapies. The mechanism(s) underlying this association remain unclear, thus we assessed the integrated molecular, metabolic, and immune profile of tumors, as well as gut microbiome features, for associations with patient body mass index (BMI).Experimental Design:Associations between BMI [normal (NL < 25) or OW/OB (BMI ≥ 25)] and tumor or microbiome characteristics were examined in specimens from 782 patients with metastatic melanoma across 7 cohorts. DNA associations were evaluated in The Cancer Genome Atlas cohort. RNA sequencing from 4 cohorts (n = 357) was batch corrected and gene set enrichment analysis (GSEA) by BMI category was performed. Metabolic profiling was conducted in a subset of patients (x = 36) by LC/MS, and in flow-sorted melanoma tumor cells (x = 37) and patient-derived melanoma cell lines (x = 17) using the Seahorse XF assay. Gut microbiome features were examined in an independent cohort (n = 371).Results:DNA mutations and copy number variations were not associated with BMI. GSEA demonstrated that tumors from OW/OB patients were metabolically quiescent, with downregulation of oxidative phosphorylation and multiple other metabolic pathways. Direct metabolite analysis and functional metabolic profiling confirmed decreased central carbon metabolism in OW/OB metastatic melanoma tumors and patient-derived cell lines. The overall structure, diversity, and taxonomy of the fecal microbiome did not differ by BMI.Conclusions:These findings suggest that the host metabolic phenotype influences melanoma metabolism and provide insight into the improved outcomes observed in OW/OB patients with metastatic melanoma treated with ICIs and targeted therapies.See related commentary by Smalley, p. 5

Differential gene expression analysis for covariates controlled.

Body mass index values by patient ID for all RNASeq cohorts.

Purpose:Small-cell lung cancer (SCLC) has been treated clinically as a homogeneous disease, but recent discoveries suggest that SCLC is heterogeneous. Whether metabolic differences exist among SCLC subtypes is largely unexplored. In this study, we aimed to determine whether metabolic vulnerabilities exist between SCLC subtypes that can be therapeutically exploited.Experimental Design:We performed steady state metabolomics on tumors isolated from distinct genetically engineered mouse models (GEMM) representing the MYC- and MYCL-driven subtypes of SCLC. Using genetic and pharmacologic approaches, we validated our findings in chemo-naïve and -resistant human SCLC cell lines, multiple GEMMs, four human cell line xenografts, and four newly derived PDX models.Results:We discover that SCLC subtypes driven by different MYC family members have distinct metabolic profiles. MYC-driven SCLC preferentially depends on arginine-regulated pathways including polyamine biosynthesis and mTOR pathway activation. Chemo-resistant SCLC cells exhibit increased MYC expression and similar metabolic liabilities as chemo-naïve MYC-driven cells. Arginine depletion with pegylated arginine deiminase (ADI-PEG 20) dramatically suppresses tumor growth and promotes survival of mice specifically with MYC-driven tumors, including in GEMMs, human cell line xenografts, and a patient-derived xenograft from a relapsed patient. Finally, ADI-PEG 20 is significantly more effective than the standard-of-care chemotherapy.Conclusions:These data identify metabolic heterogeneity within SCLC and suggest arginine deprivation as a subtype-specific therapeutic vulnerability for MYC-driven SCLC.

Abbreviations used in the manuscript.

In KRAS-mutant lung adenocarcinoma, tumors with LKB1 loss (KL) are highly enriched for concurrent KEAP1 mutations, which activate the KEAP1/NRF2 pathway (KLK). Here, we investigated the biological consequences of these cooccurring alterations and explored whether they conferred specific therapeutic vulnerabilities. Compared with KL tumors, KLK tumors exhibited increased expression of genes involved in glutamine metabolism, the tricarboxylic acid cycle, and the redox homeostasis signature. Using isogenic pairs with knockdown or overexpression of LKB1, KEAP1, and NRF2, we found that LKB1 loss results in increased energetic and redox stress marked by increased levels of intracellular reactive oxygen species and decreased levels of ATP, NADPH/NADP+ ratio, and glutathione. Activation of the KEAP1/NRF2 axis in LKB1-deficient cells enhanced cell survival and played a critical role in the maintenance of energetic and redox homeostasis in a glutamine-dependent manner. LKB1 and the KEAP1/NRF2 pathways cooperatively drove metabolic reprogramming and enhanced sensitivity to the glutaminase inhibitor CB-839 in vitro and in vivo. Overall, these findings elucidate the adaptive advantage provided by KEAP1/NRF2 pathway activation in KL tumors and support clinical testing of glutaminase inhibitor in subsets of KRAS-mutant lung adenocarcinoma.Significance:In KRAS-mutant non–small cell lung cancer, LKB1 loss results in enhanced energetic/redox stress, which is tolerated, in part, through cooccurring KEAP1/NRF2–dependent metabolic adaptations, thus enhancing glutamine dependence and vulnerability to glutaminase inhibition.

Supplementary Figure from Integrated Metabolic Profiling and Transcriptional Analysis Reveals Therapeutic Modalities for Targeting Rapidly Proliferating Breast Cancers

Metabolic dysregulation is a prominent feature in breast cancer, but it remains poorly characterized in patient tumors. In this study, untargeted metabolomics analysis of triple-negative breast cancer (TNBC) and patient with estrogen receptor (ER)–positive breast cancer samples, as well as TNBC patient-derived xenografts (PDX), revealed two major metabolic groups independent of breast cancer histologic subtypes: a “Nucleotide/Carbohydrate-Enriched” group and a “Lipid/Fatty Acid-Enriched” group. Cell lines grown in vivo more faithfully recapitulated the metabolic profiles of patient tumors compared with those grown in vitro. Integrated metabolic and gene expression analyses identified genes that strongly correlate with metabolic dysregulation and predict patient prognosis. As a proof of principle, targeting Nucleotide/Carbohydrate-Enriched TNBC cell lines or PDX xenografts with a pyrimidine biosynthesis inhibitor or a glutaminase inhibitor led to therapeutic efficacy. In multiple in vivo models of TNBC, treatment with the pyrimidine biosynthesis inhibitor conferred better therapeutic outcomes than chemotherapeutic agents. This study provides a metabolic stratification of breast tumor samples that can guide the selection of effective therapeutic strategies targeting breast cancer subsets. In addition, we have developed a public, interactive data visualization portal (http://brcametab.org) based on the data generated from this study to facilitate future research.Significance:A multiomics strategy that integrates metabolic and gene expression profiling in patient tumor samples and animal models identifies effective pharmacologic approaches to target rapidly proliferating breast tumor subtypes.

Branched-chain amino acid transaminase 1 (BCAT1) is upregulated selectively in human isocitrate dehydrogenase (IDH) wildtype (WT) but not mutant glioblastoma multiforme (GBM) and promotes IDHWT GBM growth. Through a metabolic synthetic lethal screen, we report here that α-ketoglutarate (AKG) kills IDHWT GBM cells when BCAT1 protein is lost, which is reversed by reexpression of BCAT1 or supplementation with branched-chain α-ketoacids (BCKA), downstream metabolic products of BCAT1. In patient-derived IDHWT GBM tumors in vitro and in vivo, cotreatment of BCAT1 inhibitor gabapentin and AKG resulted in synthetic lethality. However, AKG failed to evoke a synthetic lethal effect with loss of BCAT2, BCKDHA, or GPT2 in IDHWT GBM cells. Mechanistically, loss of BCAT1 increased the NAD+/NADH ratio but impaired oxidative phosphorylation, mTORC1 activity, and nucleotide biosynthesis. These metabolic alterations were synergistically augmented by AKG treatment, thereby causing mitochondrial dysfunction and depletion of cellular building blocks, including ATP, nucleotides, and proteins. Partial restoration of ATP, nucleotides, proteins, and mTORC1 activity by BCKA supplementation prevented IDHWT GBM cell death conferred by the combination of BCAT1 loss and AKG. These findings define a targetable metabolic vulnerability in the most common subset of GBM that is currently incurable.Significance:Metabolic synthetic lethal screening in IDHWT glioblastoma defines a vulnerability to ΑΚG following BCAT1 loss, uncovering a therapeutic strategy to improve glioblastoma treatment.See related commentary by Meurs and Nagrath, p. 2354

Supplementary Table from Integrated Metabolic Profiling and Transcriptional Analysis Reveals Therapeutic Modalities for Targeting Rapidly Proliferating Breast Cancers

Supplementary Data from Targeting BCAT1 Combined with α-Ketoglutarate Triggers Metabolic Synthetic Lethality in Glioblastoma

Supplemental Figures 1-6 and Supplemental Methods

Supplementary bioinformatic analysis and CB-839 effects on in vitro cell proliferation, ROS stress and metabolism.

Supplementary Figure 2 from Systemic Treatment with the Antidiabetic Drug Metformin Selectively Impairs p53-Deficient Tumor Cell Growth

Supplementary Methods, Figures 1-5, Table 1 from Glioblastoma Cells Require Glutamate Dehydrogenase to Survive Impairments of Glucose Metabolism or Akt Signaling