bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Tissue-Specific Oncogenic Activity of KRASA146T
Authors: Poulin Emily J. , Bera Asim K. , Lu Jia , Lin Yi-Jang , Strasser Samantha Dale , Paulo Joao A. , Huang Tannie Q. , Morales Carolina , Yan Wei , Cook Joshua , Nowak Jonathan A. , Brubaker Douglas K. , Joughin Brian A. , Johnson Christian W. , DeStefanis Rebecca A. , Ghazi Phaedra C. , Gondi Sudershan , Wales Thomas E. , Iacob Roxana E. , Bogdanova Lana , Gierut Jessica J. , Li Yina , Engen John R. , Perez-Mancera Pedro A. , Braun Benjamin S. , Gygi Steven P. , Lauffenburger Douglas A. , Westover Kenneth D. , Haigis Kevin M.
Published: March 2024

Abstract
KRAS is the most frequently mutated oncogene. The incidence of specific KRAS alleles varies between cancers from different sites, but it is unclear whether allelic selection results from biological selection for specific mutant KRAS proteins. We used a cross-disciplinary approach to compare KRASG12D, a common mutant form, and KRASA146T, a mutant that occurs only in selected cancers. Biochemical and structural studies demonstrated that KRASA146T exhibits a marked extension of switch 1 away from the protein body and nucleotide binding site, which activates KRAS by promoting a high rate of intrinsic and guanine nucleotide exchange factor–induced nucleotide exchange. Using mice genetically engineered to express either allele, we found that KRASG12D and KRASA146T exhibit distinct tissue-specific effects on homeostasis that mirror mutational frequencies in human cancers. These tissue-specific phenotypes result from allele-specific signaling properties, demonstrating that context-dependent variations in signaling downstream of different KRAS mutants drive the KRAS mutational pattern seen in cancer.
Significance:
Although epidemiologic and clinical studies have suggested allele-specific behaviors for KRAS, experimental evidence for allele-specific biological properties is limited. We combined structural biology, mass spectrometry, and mouse modeling to demonstrate that the selection for specific KRAS mutants in human cancers from different tissues is due to their distinct signaling properties.

See related commentary by Hobbs and Der, p. 696.

This article is highlighted in the In This Issue feature, p. 681
Data from Targeting DNA Damage Response Promotes Antitumor Immunity through STING-Mediated T-cell Activation in Small Cell Lung Cancer
Authors: Sen Triparna , Rodriguez B. Leticia , Chen Limo , Corte Carminia M. Della , Morikawa Naoto , Fujimoto Junya , Cristea Sandra , Nguyen Thuyen , Diao Lixia , Li Lerong , Fan Youhong , Yang Yongbin , Wang Jing , Glisson Bonnie S. , Wistuba Ignacio I. , Sage Julien , Heymach John V. , Gibbons Don L. , Byers Lauren A.
Published: March 2024

Abstract
Despite recent advances in the use of immunotherapy, only a minority of patients with small cell lung cancer (SCLC) respond to immune checkpoint blockade (ICB). Here, we show that targeting the DNA damage response (DDR) proteins PARP and checkpoint kinase 1 (CHK1) significantly increased protein and surface expression of PD-L1. PARP or CHK1 inhibition remarkably potentiated the antitumor effect of PD-L1 blockade and augmented cytotoxic T-cell infiltration in multiple immunocompetent SCLC in vivo models. CD8+ T-cell depletion reversed the antitumor effect, demonstrating the role of CD8+ T cells in combined DDR–PD-L1 blockade in SCLC. We further demonstrate that DDR inhibition activated the STING/TBK1/IRF3 innate immune pathway, leading to increased levels of chemokines such as CXCL10 and CCL5 that induced activation and function of cytotoxic T lymphocytes. Knockdown of cGAS and STING successfully reversed the antitumor effect of combined inhibition of DDR and PD-L1. Our results define previously unrecognized innate immune pathway–mediated immunomodulatory functions of DDR proteins and provide a rationale for combining PARP/CHK1 inhibitors and immunotherapies in SCLC.
Significance:
Our results define previously unrecognized immunomodulatory functions of DDR inhibitors and suggest that adding PARP or CHK1 inhibitors to ICB may enhance treatment efficacy in patients with SCLC. Furthermore, our study supports a role of innate immune STING pathway in DDR-mediated antitumor immunity in SCLC.

See related commentary by Hiatt and MacPherson, p. 584.

This article is highlighted in the In This Issue feature, p. 565
Data from Discovery of Selective Estrogen Receptor Covalent Antagonists for the Treatment of ERαWT and ERαMUT Breast Cancer
Authors: Puyang Xiaoling , Furman Craig , Zheng Guo Zhu , Wu Zhenhua J. , Banka Deepti , Aithal Kiran , Agoulnik Sergei , Bolduc David M. , Buonamici Silvia , Caleb Benjamin , Das Subhasree , Eckley Sean , Fekkes Peter , Hao Ming-Hong , Hart Andrew , Houtman René , Irwin Sean , Joshi Jaya J. , Karr Craig , Kim Amy , Kumar Namita , Kumar Pavan , Kuznetsov Galina , Lai Weidong G. , Larsen Nicholas , Mackenzie Crystal , Martin Lesley-Ann , Melchers Diana , Moriarty Alyssa , Nguyen Tuong-Vi , Norris John , O'Shea Morgan , Pancholi Sunil , Prajapati Sudeep , Rajagopalan Sujatha , Reynolds Dominic J. , Rimkunas Victoria , Rioux Nathalie , Ribas Ricardo , Siu Amy , Sivakumar Sasirekha , Subramanian Vanitha , Thomas Michael , Vaillancourt Frédéric H. , Wang John , Wardell Suzanne , Wick Michael J. , Yao Shihua , Yu Lihua , Warmuth Markus , Smith Peter G. , Zhu Ping , Korpal Manav
Published: March 2024

Abstract
Mutations in estrogen receptor alpha (ERα) that confer resistance to existing classes of endocrine therapies are detected in up to 30% of patients who have relapsed during endocrine treatments. Because a significant proportion of therapy-resistant breast cancer metastases continue to be dependent on ERα signaling, there remains a critical need to develop the next generation of ERα antagonists that can overcome aberrant ERα activity. Through our drug-discovery efforts, we identified H3B-5942, which covalently inactivates both wild-type and mutant ERα by targeting Cys530 and enforcing a unique antagonist conformation. H3B-5942 belongs to a class of ERα antagonists referred to as selective estrogen receptor covalent antagonists (SERCA). In vitro comparisons of H3B-5942 with standard-of-care (SoC) and experimental agents confirmed increased antagonist activity across a panel of ERαWT and ERαMUT cell lines. In vivo, H3B-5942 demonstrated significant single-agent antitumor activity in xenograft models representing ERαWT and ERαY537S breast cancer that was superior to fulvestrant. Lastly, H3B-5942 potency can be further improved in combination with CDK4/6 or mTOR inhibitors in both ERαWT and ERαMUT cell lines and/or tumor models. In summary, H3B-5942 belongs to a class of orally available ERα covalent antagonists with an improved profile over SoCs.

Significance: Nearly 30% of endocrine therapy–resistant breast cancer metastases harbor constitutively activating mutations in ERα. SERCA H3B-5942 engages C530 of both ERαWT and ERαMUT, promotes a unique antagonist conformation, and demonstrates improved in vitro and in vivo activity over SoC agents. Importantly, single-agent efficacy can be further enhanced by combining with CDK4/6 or mTOR inhibitors. Cancer Discov; 8(9); 1176–93. ©2018 AACR.

This article is highlighted in the In This Issue feature, p. 1047
Data from EIF1AX and RAS Mutations Cooperate to Drive Thyroid Tumorigenesis through ATF4 and c-MYC
Authors: Krishnamoorthy Gnana P. , Davidson Natalie R. , Leach Steven D. , Zhao Zhen , Lowe Scott W. , Lee Gina , Landa Iňigo , Nagarajah James , Saqcena Mahesh , Singh Kamini , Wendel Hans-Guido , Dogan Snjezana , Tamarapu Prasanna P. , Blenis John , Ghossein Ronald A. , Knauf Jeffrey A. , Rätsch Gunnar , Fagin James A.
Published: March 2024

Abstract
Translation initiation is orchestrated by the cap binding and 43S preinitiation complexes (PIC). Eukaryotic initiation factor 1A (EIF1A) is essential for recruitment of the ternary complex and for assembling the 43S PIC. Recurrent EIF1AX mutations in papillary thyroid cancers are mutually exclusive with other drivers, including RAS. EIF1AX mutations are enriched in advanced thyroid cancers, where they display a striking co-occurrence with RAS, which cooperates to induce tumorigenesis in mice and isogenic cell lines. The C-terminal EIF1AX-A113splice mutation is the most prevalent in advanced thyroid cancer. EIF1AX-A113splice variants stabilize the PIC and induce ATF4, a sensor of cellular stress, which is co-opted to suppress EIF2α phosphorylation, enabling a general increase in protein synthesis. RAS stabilizes c-MYC, an effect augmented by EIF1AX-A113splice. ATF4 and c-MYC induce expression of amino acid transporters and enhance sensitivity of mTOR to amino acid supply. These mutually reinforcing events generate therapeutic vulnerabilities to MEK, BRD4, and mTOR kinase inhibitors.
Significance:
Mutations of EIF1AX, a component of the translation PIC, co-occur with RAS in advanced thyroid cancers and promote tumorigenesis. EIF1AX-A113splice drives an ATF4-induced dephosphorylation of EIF2α, resulting in increased protein synthesis. ATF4 also cooperates with c-MYC to sensitize mTOR to amino acid supply, thus generating vulnerability to mTOR kinase inhibitors.

This article is highlighted in the In This Issue feature, p. 151
Data from BRD4 Profiling Identifies Critical Chronic Lymphocytic Leukemia Oncogenic Circuits and Reveals Sensitivity to PLX51107, a Novel Structurally Distinct BET Inhibitor
Authors: Ozer Hatice Gulcin , El-Gamal Dalia , Powell Ben , Hing Zachary A. , Blachly James S. , Harrington Bonnie , Mitchell Shaneice , Grieselhuber Nicole R. , Williams Katie , Lai Tzung-Huei , Alinari Lapo , Baiocchi Robert A. , Brinton Lindsey , Baskin Elizabeth , Cannon Matthew , Beaver Larry , Goettl Virginia M. , Lucas David M. , Woyach Jennifer A. , Sampath Deepa , Lehman Amy M. , Yu Lianbo , Zhang Jiazhong , Ma Yan , Zhang Ying , Spevak Wayne , Shi Songyuan , Severson Paul , Shellooe Rafe , Carias Heidi , Tsang Garson , Dong Ken , Ewing Todd , Marimuthu Adhirai , Tantoy Christina , Walters Jason , Sanftner Laura , Rezaei Hamid , Nespi Marika , Matusow Bernice , Habets Gaston , Ibrahim Prabha , Zhang Chao , Mathé Ewy A. , Bollag Gideon , Byrd John C. , Lapalombella Rosa
Published: March 2024

Abstract
Bromodomain and extra-terminal (BET) family proteins are key regulators of gene expression in cancer. Herein, we utilize BRD4 profiling to identify critical pathways involved in pathogenesis of chronic lymphocytic leukemia (CLL). BRD4 is overexpressed in CLL and is enriched proximal to genes upregulated or de novo expressed in CLL with known functions in disease pathogenesis and progression. These genes, including key members of the B-cell receptor (BCR) signaling pathway, provide a rationale for this therapeutic approach to identify new targets in alternative types of cancer. Additionally, we describe PLX51107, a structurally distinct BET inhibitor with novel in vitro and in vivo pharmacologic properties that emulates or exceeds the efficacy of BCR signaling agents in preclinical models of CLL. Herein, the discovery of the involvement of BRD4 in the core CLL transcriptional program provides a compelling rationale for clinical investigation of PLX51107 as epigenetic therapy in CLL and application of BRD4 profiling in other cancers.

Significance: To date, functional studies of BRD4 in CLL are lacking. Through integrated genomic, functional, and pharmacologic analyses, we uncover the existence of BRD4-regulated core CLL transcriptional programs and present preclinical proof-of-concept studies validating BET inhibition as an epigenetic approach to target BCR signaling in CLL. Cancer Discov; 8(4); 458–77. ©2018 AACR.

This article is highlighted in the In This Issue feature, p. 371
Data from Aurora A Kinase Inhibition Is Synthetic Lethal with Loss of the RB1 Tumor Suppressor Gene
Authors: Gong Xueqian , Du Jian , Parsons Stephen H. , Merzoug Farhana F. , Webster Yue , Iversen Philip W. , Chio Li-Chun , Van Horn Robert D. , Lin Xi , Blosser Wayne , Han Bomie , Jin Shaoling , Yao Sufang , Bian Huimin , Ficklin Chris , Fan Li , Kapoor Avnish , Antonysamy Stephen , Mc Nulty Ann M. , Froning Karen , Manglicmot Danalyn , Pustilnik Anna , Weichert Kenneth , Wasserman Stephen R. , Dowless Michele , Marugán Carlos , Baquero Carmen , Lallena María José , Eastman Scott W. , Hui Yu-Hua , Dieter Matthew Z. , Doman Thompson , Chu Shaoyou , Qian Hui-Rong , Ye Xiang S. , Barda David A. , Plowman Gregory D. , Reinhard Christoph , Campbell Robert M. , Henry James R. , Buchanan Sean G.
Published: March 2024

Abstract
Loss-of-function mutations in the retinoblastoma gene RB1 are common in several treatment-refractory cancers such as small-cell lung cancer and triple-negative breast cancer. To identify drugs synthetic lethal with RB1 mutation (RB1mut), we tested 36 cell-cycle inhibitors using a cancer cell panel profiling approach optimized to discern cytotoxic from cytostatic effects. Inhibitors of the Aurora kinases AURKA and AURKB showed the strongest RB1 association in this assay. LY3295668, an AURKA inhibitor with over 1,000-fold selectivity versus AURKB, is distinguished by minimal toxicity to bone marrow cells at concentrations active against RB1mut cancer cells and leads to durable regression of RB1mut tumor xenografts at exposures that are well tolerated in rodents. Genetic suppression screens identified enforcers of the spindle-assembly checkpoint (SAC) as essential for LY3295668 cytotoxicity in RB1-deficient cancers and suggest a model in which a primed SAC creates a unique dependency on AURKA for mitotic exit and survival.
Significance:
The identification of a synthetic lethal interaction between RB1 and AURKA inhibition, and the discovery of a drug that can be dosed continuously to achieve uninterrupted inhibition of AURKA kinase activity without myelosuppression, suggest a new approach for the treatment of RB1-deficient malignancies, including patients progressing on CDK4/6 inhibitors.

See related commentary by Dick and Li, p. 169.

This article is highlighted in the In This Issue feature, p. 151
Data from Remodeling of the Collagen Matrix in Aging Skin Promotes Melanoma Metastasis and Affects Immune Cell Motility
Authors: Kaur Amanpreet , Ecker Brett L. , Douglass Stephen M. , Kugel Curtis H. , Webster Marie R. , Almeida Filipe V. , Somasundaram Rajasekharan , Hayden James , Ban Ehsan , Ahmadzadeh Hossein , Franco-Barraza Janusz , Shah Neelima , Mellis Ian A. , Keeney Frederick , Kossenkov Andrew , Tang Hsin-Yao , Yin Xiangfan , Liu Qin , Xu Xiaowei , Fane Mitchell , Brafford Patricia , Herlyn Meenhard , Speicher David W. , Wargo Jennifer A. , Tetzlaff Michael T. , Haydu Lauren E. , Raj Arjun , Shenoy Vivek , Cukierman Edna , Weeraratna Ashani T.
Published: March 2024

Abstract
Physical changes in skin are among the most visible signs of aging. We found that young dermal fibroblasts secrete high levels of extracellular matrix (ECM) constituents, including proteoglycans, glycoproteins, and cartilage-linking proteins. The most abundantly secreted was HAPLN1, a hyaluronic and proteoglycan link protein. HAPLN1 was lost in aged fibroblasts, resulting in a more aligned ECM that promoted metastasis of melanoma cells. Reconstituting HAPLN1 inhibited metastasis in an aged microenvironment, in 3-D skin reconstruction models, and in vivo. Intriguingly, aged fibroblast-derived matrices had the opposite effect on the migration of T cells, inhibiting their motility. HAPLN1 treatment of aged fibroblasts restored motility of mononuclear immune cells, while impeding that of polymorphonuclear immune cells, which in turn affected regulatory T-cell recruitment. These data suggest that although age-related physical changes in the ECM can promote tumor cell motility, they may adversely affect the motility of some immune cells, resulting in an overall change in the immune microenvironment. Understanding the physical changes in aging skin may provide avenues for more effective therapy for older patients with melanoma.
Significance:
These data shed light on the mechanochemical interactions that occur between aged skin, tumor, and immune cell populations, which may affect tumor metastasis and immune cell infiltration, with implications for the efficacy of current therapies for melanoma.

See related commentary by Marie and Merlino, p. 19.

This article is highlighted in the In This Issue feature, p. 1
Data from Conversion of PRPS Hexamer to Monomer by AMPK-Mediated Phosphorylation Inhibits Nucleotide Synthesis in Response to Energy Stress
Authors: Qian Xu , Li Xinjian , Tan Lin , Lee Jong-Ho , Xia Yan , Cai Qingsong , Zheng Yanhua , Wang Hongxia , Lorenzi Philip L. , Lu Zhimin
Published: March 2024

Abstract
Tumors override energy stress to grow. However, how nucleotide synthesis is regulated under energy stress is unclear. We demonstrate here that glucose deprivation or hypoxia results in the AMPK-mediated phosphorylation of phosphoribosyl pyrophosphate synthetase 1 (PRPS1) S180 and PRPS2 S183, leading to conversion of PRPS hexamers to monomers and thereby inhibiting PRPS1/2 activity, nucleotide synthesis, and nicotinamide adenine dinucleotide (NAD) production. Knock-in of nonphosphorylatable PRPS1/2 mutants, which have uninhibited activity, in brain tumor cells under energy stress exhausts cellular ATP and NADPH and increases reactive oxygen species levels, thereby promoting cell apoptosis. The expression of those mutants inhibits brain tumor formation and enhances the inhibitory effect of the glycolysis inhibitor 2-deoxy-d-glucose on tumor growth. Our findings highlight the significance of recalibrating tumor cell metabolism by fine-tuning nucleotide and NAD synthesis in tumor growth.

Significance: Our findings elucidate an instrumental function of AMPK in direct regulation of nucleic acid and NAD synthesis in tumor cells in response to energy stress. AMPK phosphorylates PRPS1/2, converts PRPS1/2 hexamers to monomers, and inhibits PRPS1/2 activity and subsequent nucleotide and NAD synthesis to maintain tumor cell growth and survival. Cancer Discov; 8(1); 94–107. ©2017 AACR.

This article is highlighted in the In This Issue feature, p. 1
Data from Exploiting Drug Addiction Mechanisms to Select against MAPKi-Resistant Melanoma
Authors: Hong Aayoung , Moriceau Gatien , Sun Lu , Lomeli Shirley , Piva Marco , Damoiseaux Robert , Holmen Sheri L. , Sharpless Norman E. , Hugo Willy , Lo Roger S.
Published: March 2024

Abstract
Melanoma resistant to MAPK inhibitors (MAPKi) displays loss of fitness upon experimental MAPKi withdrawal and, clinically, may be resensitized to MAPKi therapy after a drug holiday. Here, we uncovered and therapeutically exploited the mechanisms of MAPKi addiction in MAPKi-resistant BRAFMUT or NRASMUT melanoma. MAPKi-addiction phenotypes evident upon drug withdrawal spanned transient cell-cycle slowdown to cell-death responses, the latter of which required a robust phosphorylated ERK (pERK) rebound. Generally, drug withdrawal–induced pERK rebound upregulated p38–FRA1–JUNB–CDKN1A and downregulated proliferation, but only a robust pERK rebound resulted in DNA damage and parthanatos-related cell death. Importantly, pharmacologically impairing DNA damage repair during MAPKi withdrawal augmented MAPKi addiction across the board by converting a cell-cycle deceleration to a caspase-dependent cell-death response or by furthering parthanatos-related cell death. Specifically in MEKi-resistant NRASMUT or atypical BRAFMUT melanoma, treatment with a type I RAF inhibitor intensified pERK rebound elicited by MEKi withdrawal, thereby promoting a cell death–predominant MAPKi-addiction phenotype. Thus, MAPKi discontinuation upon disease progression should be coupled with specific strategies that augment MAPKi addiction.

Significance: Discontinuing targeted therapy may select against drug-resistant tumor clones, but drug-addiction mechanisms are ill-defined. Using melanoma resistant to but withdrawn from MAPKi, we defined a synthetic lethality between supraphysiologic levels of pERK and DNA damage. Actively promoting this synthetic lethality could rationalize sequential/rotational regimens that address evolving vulnerabilities. Cancer Discov; 8(1); 74–93. ©2017 AACR.

See related commentary by Stern, p. 20.

This article is highlighted in the In This Issue feature, p. 1
Data from H3.3 G34W Promotes Growth and Impedes Differentiation of Osteoblast-Like Mesenchymal Progenitors in Giant Cell Tumor of Bone
Authors: Khazaei Sima , De Jay Nicolas , Deshmukh Shriya , Hendrikse Liam D. , Jawhar Wajih , Chen Carol C.L. , Mikael Leonie G. , Faury Damien , Marchione Dylan M. , Lanoix Joel , Bonneil Éric , Ishii Takeaki , Jain Siddhant U. , Rossokhata Kateryna , Sihota Tianna S. , Eveleigh Robert , Lisi Véronique , Harutyunyan Ashot S. , Jung Sungmi , Karamchandani Jason , Dickson Brendan C. , Turcotte Robert , Wunder Jay S. , Thibault Pierre , Lewis Peter W. , Garcia Benjamin A. , Mack Stephen C. , Taylor Michael D. , Garzia Livia , Kleinman Claudia L. , Jabado Nada
Published: March 2024

Abstract
Glycine 34-to-tryptophan (G34W) substitutions in H3.3 arise in approximately 90% of giant cell tumor of bone (GCT). Here, we show H3.3 G34W is necessary for tumor formation. By profiling the epigenome, transcriptome, and secreted proteome of patient samples and tumor-derived cells CRISPR–Cas9-edited for H3.3 G34W, we show that H3.3K36me3 loss on mutant H3.3 alters the deposition of the repressive H3K27me3 mark from intergenic to genic regions, beyond areas of H3.3 deposition. This promotes redistribution of other chromatin marks and aberrant transcription, altering cell fate in mesenchymal progenitors and hindering differentiation. Single-cell transcriptomics reveals that H3.3 G34W stromal cells recapitulate a neoplastic trajectory from a SPP1+ osteoblast-like progenitor population toward an ACTA2+ myofibroblast-like population, which secretes extracellular matrix ligands predicted to recruit and activate osteoclasts. Our findings suggest that H3.3 G34W leads to GCT by sustaining a transformed state in osteoblast-like progenitors, which promotes neoplastic growth, pathologic recruitment of giant osteoclasts, and bone destruction.
Significance:
This study shows that H3.3 G34W drives GCT tumorigenesis through aberrant epigenetic remodeling, altering differentiation trajectories in mesenchymal progenitors. H3.3 G34W promotes in neoplastic stromal cells an osteoblast-like progenitor state that enables undue interactions with the tumor microenvironment, driving GCT pathogenesis. These epigenetic changes may be amenable to therapeutic targeting in GCT.

See related commentary by Licht, p. 1794.

This article is highlighted in the In This Issue feature, p. 1775
Data from In Vivo Epigenetic CRISPR Screen Identifies Asf1a as an Immunotherapeutic Target in Kras-Mutant Lung Adenocarcinoma
Authors: Li Fei , Huang Qingyuan , Luster Troy A. , Hu Hai , Zhang Hua , Ng Wai-Lung , Khodadadi-Jamayran Alireza , Wang Wei , Chen Ting , Deng Jiehui , Ranieri Michela , Fang Zhaoyuan , Pyon Val , Dowling Catríona M. , Bagdatlioglu Ece , Almonte Christina , Labbe Kristen , Silver Heather , Rabin Alexandra R. , Jani Kandarp , Tsirigos Aristotelis , Papagiannakopoulos Thales , Hammerman Peter S. , Velcheti Vamsidhar , Freeman Gordon J. , Qi Jun , Miller George , Wong Kwok-Kin
Published: March 2024

Abstract
Despite substantial progress in lung cancer immunotherapy, the overall response rate in patients with KRAS-mutant lung adenocarcinoma (LUAD) remains low. Combining standard immunotherapy with adjuvant approaches that enhance adaptive immune responses—such as epigenetic modulation of antitumor immunity—is therefore an attractive strategy. To identify epigenetic regulators of tumor immunity, we constructed an epigenetic-focused single guide RNA library and performed an in vivo CRISPR screen in a KrasG12D/Trp53−/− LUAD model. Our data showed that loss of the histone chaperone Asf1a in tumor cells sensitizes tumors to anti–PD-1 treatment. Mechanistic studies revealed that tumor cell–intrinsic Asf1a deficiency induced immunogenic macrophage differentiation in the tumor microenvironment by upregulating GM-CSF expression and potentiated T-cell activation in combination with anti–PD-1. Our results provide a rationale for a novel combination therapy consisting of ASF1A inhibition and anti–PD-1 immunotherapy.
Significance:
Using an in vivo epigenetic CRISPR screen, we identified Asf1a as a critical regulator of LUAD sensitivity to anti–PD-1 therapy. Asf1a deficiency synergized with anti–PD-1 immunotherapy by promoting M1-like macrophage polarization and T-cell activation. Thus, we provide a new immunotherapeutic strategy for this subtype of patients with LUAD.

See related commentary by Menzel and Black, p. 179.

This article is highlighted in the In This Issue feature, p. 161
Data from Epigenetic Switch–Induced Viral Mimicry Evasion in Chemotherapy-Resistant Breast Cancer
Authors: Deblois Geneviève , Tonekaboni Seyed Ali Madani , Grillo Giacomo , Martinez Constanza , Kao Yunchi Ingrid , Tai Felicia , Ettayebi Ilias , Fortier Anne-Marie , Savage Paul , Fedor Alexandra N. , Liu Xiaojing , Guilhamon Paul , Lima-Fernandes Evelyne , Murison Alex , Kuasne Hellen , Ba-alawi Wail , Cescon David W. , Arrowsmith Cheryl H. , De Carvalho Daniel D. , Haibe-Kains Benjamin , Locasale Jason W. , Park Morag , Lupien Mathieu
Published: March 2024

Abstract
Tumor progression upon treatment arises from preexisting resistant cancer cells and/or adaptation of persister cancer cells committing to an expansion phase. Here, we show that evasion from viral mimicry response allows the growth of taxane-resistant triple-negative breast cancer (TNBC). This is enabled by an epigenetic state adapted to taxane-induced metabolic stress, where DNA hypomethylation over loci enriched in transposable elements (TE) is compensated by large chromatin domains of H3K27me3 to warrant TE repression. This epigenetic state creates a vulnerability to epigenetic therapy against EZH2, the H3K27me3 methyltransferase, which alleviates TE repression in taxane-resistant TNBC, leading to double-stranded RNA production and growth inhibition through viral mimicry response. Collectively, our results illustrate how epigenetic states over TEs promote cancer progression under treatment and can inform about vulnerabilities to epigenetic therapy.
Significance:
Drug-resistant cancer cells represent a major barrier to remission for patients with cancer. Here we show that drug-induced metabolic perturbation and epigenetic states enable evasion from the viral mimicry response induced by chemotherapy in TNBC. These epigenetic states define a vulnerability to epigenetic therapy using EZH2 inhibitors in taxane-resistant TNBC.

See related commentary by Janin and Esteller, p. 1258.

This article is highlighted in the In This Issue feature, p. 1241
Data from Somatic Mutations Drive Specific, but Reversible, Epigenetic Heterogeneity States in AML
Authors: Li Sheng , Chen Xiaowen , Wang Jiahui , Meydan Cem , Glass Jacob L. , Shih Alan H. , Delwel Ruud , Levine Ross L. , Mason Christopher E. , Melnick Ari M.
Published: March 2024

Abstract
Epigenetic allele diversity is linked to inferior prognosis in acute myeloid leukemia (AML). However, the source of epiallele heterogeneity in AML is unknown. Herein we analyzed epiallele diversity in a genetically and clinically annotated AML cohort. Notably, AML driver mutations linked to transcription factors and favorable outcome are associated with epigenetic destabilization in a defined set of susceptible loci. In contrast, AML subtypes linked to inferior prognosis manifest greater abundance and highly stochastic epiallele patterning. We report an epiallele outcome classifier supporting the link between epigenetic diversity and treatment failure. Mouse models with TET2 or IDH2 mutations show that epiallele diversity is especially strongly induced by IDH mutations, precedes transformation to AML, and is enhanced by cooperation between somatic mutations. Furthermore, epiallele complexity was partially reversed by epigenetic therapies in AML driven by TET2/IDH2, suggesting that epigenetic therapy might function in part by reducing population complexity and fitness of AMLs.
Significance:
We show for the first time that epigenetic clonality is directly linked to specific mutations and that epigenetic allele diversity precedes and potentially contributes to malignant transformation. Furthermore, epigenetic clonality is reversible with epigenetic therapy agents.

This article is highlighted in the In This Issue feature, p. 1775
Data from Regulatory T-cell Depletion Alters the Tumor Microenvironment and Accelerates Pancreatic Carcinogenesis
Authors: Zhang Yaqing , Lazarus Jenny , Steele Nina G. , Yan Wei , Lee Ho-Joon , Nwosu Zeribe C. , Halbrook Christopher J. , Menjivar Rosa E. , Kemp Samantha B. , Sirihorachai Veerin R. , Velez-Delgado Ashley , Donahue Katelyn , Carpenter Eileen S. , Brown Kristee L. , Irizarry-Negron Valerie , Nevison Anna C. , Vinta Alekya , Anderson Michelle A. , Crawford Howard C. , Lyssiotis Costas A. , Frankel Timothy L. , Bednar Filip , Pasca di Magliano Marina
Published: March 2024

Abstract
Regulatory T cells (Treg) are abundant in human and mouse pancreatic cancer. To understand the contribution to the immunosuppressive microenvironment, we depleted Tregs in a mouse model of pancreatic cancer. Contrary to our expectations, Treg depletion failed to relieve immunosuppression and led to accelerated tumor progression. We show that Tregs are a key source of TGFβ ligands and, accordingly, their depletion reprogramed the fibroblast population, with loss of tumor-restraining, smooth muscle actin–expressing fibroblasts. Conversely, we observed an increase in chemokines Ccl3, Ccl6, and Ccl8 leading to increased myeloid cell recruitment, restoration of immune suppression, and promotion of carcinogenesis, an effect that was inhibited by blockade of the common CCL3/6/8 receptor CCR1. Further, Treg depletion unleashed pathologic CD4+ T-cell responses. Our data point to new mechanisms regulating fibroblast differentiation in pancreatic cancer and support the notion that fibroblasts are a heterogeneous population with different and opposing functions in pancreatic carcinogenesis.
Significance:
Here, we describe an unexpected cross-talk between Tregs and fibroblasts in pancreatic cancer. Treg depletion resulted in differentiation of inflammatory fibroblast subsets, in turn driving infiltration of myeloid cells through CCR1, thus uncovering a potentially new therapeutic approach to relieve immunosuppression in pancreatic cancer.

See related commentary by Aykut et al., p. 345.

This article is highlighted in the In This Issue feature, p. 327
Data from ID1 Mediates Escape from TGFβ Tumor Suppression in Pancreatic Cancer
Authors: Huang Yun-Han , Hu Jing , Chen Fei , Lecomte Nicolas , Basnet Harihar , David Charles J. , Witkin Matthew D. , Allen Peter J. , Leach Steven D. , Hollmann Travis J. , Iacobuzio-Donahue Christine A. , Massagué Joan
Published: March 2024

Abstract
TGFβ is an important tumor suppressor in pancreatic ductal adenocarcinoma (PDA), yet inactivation of TGFβ pathway components occurs in only half of PDA cases. TGFβ cooperates with oncogenic RAS signaling to trigger epithelial-to-mesenchymal transition (EMT) in premalignant pancreatic epithelial progenitors, which is coupled to apoptosis owing to an imbalance of SOX4 and KLF5 transcription factors. We report that PDAs that develop with the TGFβ pathway intact avert this apoptotic effect via ID1. ID1 family members are expressed in PDA progenitor cells and encode components of a set of core transcriptional regulators shared by PDAs. PDA progression selects against TGFβ-mediated repression of ID1. The sustained expression of ID1 uncouples EMT from apoptosis in PDA progenitors. AKT signaling and mechanisms linked to low-frequency genetic events converge on ID1 to preserve its expression in PDA. Our results identify ID1 as a crucial node and potential therapeutic target in PDA.
Significance:
Half of PDAs escape TGFβ-induced tumor suppression without inactivating the TGFβ pathway. We report that ID1 expression is selected for in PDAs and that ID1 uncouples TGFβ-induced EMT from apoptosis. ID1 thus emerges as a crucial regulatory node and a target of interest in PDA.

This article is highlighted in the In This Issue feature, p. 1
Data from Mutations in the RNA Splicing Factor SF3B1 Promote Tumorigenesis through MYC Stabilization
Authors: Liu Zhaoqi , Yoshimi Akihide , Wang Jiguang , Cho Hana , Chun-Wei Lee Stanley , Ki Michelle , Bitner Lillian , Chu Timothy , Shah Harshal , Liu Bo , Mato Anthony R. , Ruvolo Peter , Fabbri Giulia , Pasqualucci Laura , Abdel-Wahab Omar , Rabadan Raul
Published: March 2024

Abstract
Although mutations in the gene encoding the RNA splicing factor SF3B1 are frequent in multiple cancers, their functional effects and therapeutic dependencies are poorly understood. Here, we characterize 98 tumors and 12 isogenic cell lines harboring SF3B1 hotspot mutations, identifying hundreds of cryptic 3′ splice sites common and specific to different cancer types. Regulatory network analysis revealed that the most common SF3B1 mutation activates MYC via effects conserved across human and mouse cells. SF3B1 mutations promote decay of transcripts encoding the protein phosphatase 2A (PP2A) subunit PPP2R5A, increasing MYC S62 and BCL2 S70 phosphorylation which, in turn, promotes MYC protein stability and impair apoptosis, respectively. Genetic PPP2R5A restoration or pharmacologic PP2A activation impaired SF3B1-mutant tumorigenesis, elucidating a therapeutic approach to aberrant splicing by mutant SF3B1.
Significance:
Here, we identify that mutations in SF3B1, the most commonly mutated splicing factor gene across cancers, alter splicing of a specific subunit of the PP2A serine/threonine phosphatase complex to confer post-translational MYC and BCL2 activation, which is therapeutically intervenable using an FDA-approved drug.

See related commentary by O'Connor and Narla, p. 765.

This article is highlighted in the In This Issue feature, p. 747
Data from Tuning the Antigen Density Requirement for CAR T-cell Activity
Authors: Majzner Robbie G. , Rietberg Skyler P. , Sotillo Elena , Dong Rui , Vachharajani Vipul T. , Labanieh Louai , Myklebust June H. , Kadapakkam Meena , Weber Evan W. , Tousley Aidan M. , Richards Rebecca M. , Heitzeneder Sabine , Nguyen Sang M. , Wiebking Volker , Theruvath Johanna , Lynn Rachel C. , Xu Peng , Dunn Alexander R. , Vale Ronald D. , Mackall Crystal L.
Published: March 2024

Abstract
Insufficient reactivity against cells with low antigen density has emerged as an important cause of chimeric antigen receptor (CAR) T-cell resistance. Little is known about factors that modulate the threshold for antigen recognition. We demonstrate that CD19 CAR activity is dependent upon antigen density and that the CAR construct in axicabtagene ciloleucel (CD19-CD28ζ) outperforms that in tisagenlecleucel (CD19-4-1BBζ) against antigen-low tumors. Enhancing signal strength by including additional immunoreceptor tyrosine-based activation motifs (ITAM) in the CAR enables recognition of low-antigen-density cells, whereas ITAM deletions blunt signal and increase the antigen density threshold. Furthermore, replacement of the CD8 hinge-transmembrane (H/T) region of a 4-1BBζ CAR with a CD28-H/T lowers the threshold for CAR reactivity despite identical signaling molecules. CARs incorporating a CD28-H/T demonstrate a more stable and efficient immunologic synapse. Precise design of CARs can tune the threshold for antigen recognition and endow 4-1BBζ-CARs with enhanced capacity to recognize antigen-low targets while retaining a superior capacity for persistence.
Significance:
Optimal CAR T-cell activity is dependent on antigen density, which is variable in many cancers, including lymphoma and solid tumors. CD28ζ-CARs outperform 4-1BBζ-CARs when antigen density is low. However, 4-1BBζ-CARs can be reengineered to enhance activity against low-antigen-density tumors while maintaining their unique capacity for persistence.

This article is highlighted in the In This Issue feature, p. 627
Data from Tumor Microenvironment Remodeling Enables Bypass of Oncogenic KRAS Dependency in Pancreatic Cancer
Authors: Hou Pingping , Kapoor Avnish , Zhang Qiang , Li Jiexi , Wu Chang-Jiun , Li Jun , Lan Zhengdao , Tang Ming , Ma Xingdi , Ackroyd Jeffrey J. , Kalluri Raghu , Zhang Jianhua , Jiang Shan , Spring Denise J. , Wang Y. Alan , DePinho Ronald A.
Published: March 2024

Abstract
Oncogenic KRAS (KRAS*) is a key tumor maintenance gene in pancreatic ductal adenocarcinoma (PDAC), motivating pharmacologic targeting of KRAS* and its effectors. Here, we explored mechanisms involving the tumor microenvironment (TME) as a potential basis for resistance to targeting KRAS*. Using the inducible KrasG12D;Trp53−/− PDAC mouse model, gain-of-function screens of epigenetic regulators identified HDAC5 as the top hit enabling KRAS* independent tumor growth. HDAC5-driven escaper tumors showed a prominent neutrophil-to-macrophage switch relative to KRAS*-driven tumors. Mechanistically, HDAC5 represses Socs3, a negative regulator of chemokine CCL2, resulting in increased CCL2, which recruits CCR2+ macrophages. Correspondingly, enforced Ccl2 promotes macrophage recruitment into the TME and enables tumor recurrence following KRAS* extinction. These tumor-associated macrophages in turn provide cancer cells with trophic support including TGFβ to enable KRAS* bypass in a SMAD4-dependent manner. Our work uncovers a KRAS* resistance mechanism involving immune cell remodeling of the PDAC TME.
Significance:
Although KRAS* is required for PDAC tumor maintenance, tumors can recur following KRAS* extinction. The capacity of PDAC cancer cells to alter the TME myeloid cell composition to support KRAS*-independent tumor growth illuminates novel therapeutic targets that may enhance the effectiveness of therapies targeting KRAS* and its pathway components.

See related commentary by Carr and Fernandez-Zapico, p. 910.

This article is highlighted in the In This Issue feature, p. 890
Data from Molecular Profiling Reveals Unique Immune and Metabolic Features of Melanoma Brain Metastases
Authors: Fischer Grant M. , Jalali Ali , Kircher David A. , Lee Won-Chul , McQuade Jennifer L. , Haydu Lauren E. , Joon Aron Y. , Reuben Alexandre , de Macedo Mariana P. , Carapeto Fernando C. L. , Yang Chendong , Srivastava Anuj , Ambati Chandrashekar R. , Sreekumar Arun , Hudgens Courtney W. , Knighton Barbara , Deng Wanleng , Ferguson Sherise D. , Tawbi Hussein A. , Glitza Isabella C. , Gershenwald Jeffrey E. , Vashisht Gopal Y. N. , Hwu Patrick , Huse Jason T. , Wargo Jennifer A. , Futreal P. Andrew , Putluri Nagireddy , Lazar Alexander J. , DeBerardinis Ralph J. , Marszalek Joseph R. , Zhang Jianjun , Holmen Sheri L. , Tetzlaff Michael T. , Davies Michael A.
Published: March 2024

Abstract
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
Data from A Genetic Mouse Model Recapitulates Immune Checkpoint Inhibitor–Associated Myocarditis and Supports a Mechanism-Based Therapeutic Intervention
Authors: Wei Spencer C. , Meijers Wouter C. , Axelrod Margaret L. , Anang Nana-Ama A.S. , Screever Elles M. , Wescott Elizabeth C. , Johnson Douglas B. , Whitley Elizabeth , Lehmann Lorenz , Courand Pierre-Yves , Mancuso James J. , Himmel Lauren E. , Lebrun-Vignes Benedicte , Wleklinski Matthew J. , Knollmann Bjorn C. , Srinivasan Jayashree , Li Yu , Atolagbe Oluwatomisin T. , Rao Xiayu , Zhao Yang , Wang Jing , Ehrlich Lauren I.R. , Sharma Padmanee , Salem Joe-Elie , Balko Justin M. , Moslehi Javid J. , Allison James P.
Published: March 2024

Abstract
Immune checkpoint inhibitors (ICI) targeting CTLA4 or PD-1/PD-L1 have transformed cancer therapy but are associated with immune-related adverse events, including myocarditis. Here, we report a robust preclinical mouse model of ICI-associated myocarditis in which monoallelic loss of Ctla4 in the context of complete genetic absence of Pdcd1 leads to premature death in approximately half of mice. Premature death results from myocardial infiltration by T cells and macrophages and severe ECG abnormalities, closely recapitulating the clinical and pathologic hallmarks of ICI-associated myocarditis observed in patients. Using this model, we show that Ctla4 and Pdcd1 functionally interact in a gene dosage–dependent manner, providing a mechanism by which myocarditis arises with increased frequency in the setting of combination ICI therapy. We demonstrate that intervention with CTLA4–Ig (abatacept) is sufficient to ameliorate disease progression and additionally provide a case series of patients in which abatacept mitigates the fulminant course of ICI myocarditis.
Significance:
We provide a preclinical model of ICI-associated myocarditis which recapitulates this clinical syndrome. Using this model, we demonstrate that CTLA4 and PD-1 (ICI targets) functionally interact for myocarditis development and that intervention with CTLA4–Ig (abatacept) attenuates myocarditis, providing mechanistic rationale and preclinical support for therapeutic clinical studies.

See related commentary by Young and Bluestone, p. 537.

This article is highlighted in the In This Issue feature, p. 521
Data from β-Catenin Activation Promotes Immune Escape and Resistance to Anti–PD-1 Therapy in Hepatocellular Carcinoma
Authors: Ruiz de Galarreta Marina , Bresnahan Erin , Molina-Sánchez Pedro , Lindblad Katherine E. , Maier Barbara , Sia Daniela , Puigvehi Marc , Miguela Verónica , Casanova-Acebes María , Dhainaut Maxime , Villacorta-Martin Carlos , Singhi Aatur D. , Moghe Akshata , von Felden Johann , Tal Grinspan Lauren , Wang Shuang , Kamphorst Alice O. , Monga Satdarshan P. , Brown Brian D. , Villanueva Augusto , Llovet Josep M. , Merad Miriam , Lujambio Amaia
Published: March 2024

Abstract
PD-1 immune checkpoint inhibitors have produced encouraging results in patients with hepatocellular carcinoma (HCC). However, what determines resistance to anti–PD-1 therapies is unclear. We created a novel genetically engineered mouse model of HCC that enables interrogation of how different genetic alterations affect immune surveillance and response to immunotherapies. Expression of exogenous antigens in MYC;Trp53−/− HCCs led to T cell–mediated immune surveillance, which was accompanied by decreased tumor formation and increased survival. Some antigen-expressing MYC;Trp53−/− HCCs escaped the immune system by upregulating the β-catenin (CTNNB1) pathway. Accordingly, expression of exogenous antigens in MYC;CTNNB1 HCCs had no effect, demonstrating that β-catenin promoted immune escape, which involved defective recruitment of dendritic cells and consequently impaired T-cell activity. Expression of chemokine CCL5 in antigen-expressing MYC;CTNNB1 HCCs restored immune surveillance. Finally, β-catenin–driven tumors were resistant to anti–PD-1. In summary, β-catenin activation promotes immune escape and resistance to anti–PD-1 and could represent a novel biomarker for HCC patient exclusion.
Significance:
Determinants of response to anti–PD-1 immunotherapies in HCC are poorly understood. Using a novel mouse model of HCC, we show that β-catenin activation promotes immune evasion and resistance to anti–PD-1 therapy and could potentially represent a novel biomarker for HCC patient exclusion.

See related commentary by Berraondo et al., p. 1003.

This article is highlighted in the In This Issue feature, p. 983
Data from Oncogenic KRAS Induces NIX-Mediated Mitophagy to Promote Pancreatic Cancer
Authors: Humpton Timothy J. , Alagesan Brinda , DeNicola Gina M. , Lu Dan , Yordanov Georgi N. , Leonhardt Carl S. , Yao Melissa A. , Alagesan Priya , Zaatari Maya N. , Park Youngkyu , Skepper Jeremy N. , Macleod Kay F. , Perez-Mancera Pedro A. , Murphy Michael P. , Evan Gerard I. , Vousden Karen H. , Tuveson David A.
Published: March 2024

Abstract
Activating KRAS mutations are found in nearly all cases of pancreatic ductal adenocarcinoma (PDAC), yet effective clinical targeting of oncogenic KRAS remains elusive. Understanding of KRAS-dependent PDAC-promoting pathways could lead to the identification of vulnerabilities and the development of new treatments. We show that oncogenic KRAS induces BNIP3L/NIX expression and a selective mitophagy program that restricts glucose flux to the mitochondria and enhances redox capacity. Loss of Nix restores functional mitochondria to cells, increasing demands for NADPH reducing power and decreasing proliferation in glucose-limited conditions. Nix deletion markedly delays progression of pancreatic cancer and improves survival in a murine (KPC) model of PDAC. Although conditional Nix ablation in vivo initially results in the accumulation of mitochondria, mitochondrial content eventually normalizes via increased mitochondrial clearance programs, and pancreatic intraepithelial neoplasia (PanIN) lesions progress to PDAC. We identify the KRAS–NIX mitophagy program as a novel driver of glycolysis, redox robustness, and disease progression in PDAC.
Significance:
NIX-mediated mitophagy is a new oncogenic KRAS effector pathway that suppresses functional mitochondrial content to stimulate cell proliferation and augment redox homeostasis. This pathway promotes the progression of PanIN to PDAC and represents a new dependency in pancreatic cancer.

This article is highlighted in the In This Issue feature, p. 1143