Opposing effects of systemic and pancreas-specific inhibition of BCKDK on pancreatic carcinogenesis.

Branched-chain amino acid (BCAA) metabolism is perturbed in patients with pancreatic cancer, but the contribution of systemic or pancreas-intrinsic BCAA catabolism to pancreatic carcinogenesis is unclear. We show here that pancreas-specific loss of DBT, the E2 subunit of the branched-chain keto-acid dehydrogenase (BCKDH) complex required for BCAA oxidation, strikingly exacerbates premalignant pancreatic intraepithelial neoplasia (PanIN) lesions in KC ( ; ) mice. However, deletion of upstream enzyme BCAT2 neither phenocopied nor rescued loss of DBT in KC mice, ruling out involvement of both upstream and downstream metabolites as mediators of PanIN promotion.

The H3 oncohistone inhibits NSD2 to activate a SETD2-dependent antiviral-like immune response in KRAS-driven lung cancer.

Mutations in histone 3 at or near lysine 36 (H3K36) have dominantly acting oncogenic effects in multiple tumor types by limiting H3K36-directed methyltransferases. Paradoxically, we find that expression of the oncohistone unexpectedly inhibits tumor formation in KRAS-driven lung adenocarcinoma by inducing a potent immune-mediated tumor clearance. Mechanistically, oncohistone expression derepresses endogenous retroviral element transcription, results in the accumulation of double-stranded RNA (dsRNA), and activates an innate antiviral-like immune response that eradicates tumor growth.

Tumor suppressor genotype influences the extent and mode of immunosurveillance in lung cancer.

Unlabelled: The impact of cancer driving mutations in regulating immunosurveillance throughout tumor development remains poorly understood. To better understand the contribution of tumor genotype to immunosurveillance, we generated and validated lentiviral vectors that create an epi-allelic series of increasingly immunogenic neoantigens. This vector system is compatible with autochthonous Cre-regulated cancer models, CRISPR/Cas9-mediated somatic genome editing, and tumor barcoding.

Metastatic Competency and Tumor Spheroid Formation Are Independent Cell States Governed by RB in Lung Adenocarcinoma.

Unlabelled: Inactivation of the retinoblastoma (RB) tumor suppressor in lung adenocarcinoma is associated with the rapid acquisition of metastatic ability and the loss of lung cell lineage commitment. We previously showed that restoration of RB in advanced lung adenocarcinomas in the mouse was correlated with a decreased frequency of lineage decommitted tumors and overt metastases. To identify a causal relationship for RB and its role in reprogramming lineage commitment and reducing metastatic competency in lung adenocarcinoma, we developed multiple tumor spheroid forming lines where RB restoration could be achieved after characterization of the degree of each spheroid's lineage commitment and metastatic ability.

p53 restoration in small cell lung cancer identifies a latent cyclophilin-dependent necrosis mechanism.

The p53 tumor suppressor regulates multiple context-dependent tumor suppressive programs. Although p53 is mutated in ~90% of small cell lung cancer (SCLC) tumors, how p53 mediates tumor suppression in this context is unknown. Here, using a mouse model of SCLC in which endogenous p53 expression can be conditionally and temporally regulated, we show that SCLC tumors maintain a requirement for p53 inactivation.

Setd2 inactivation sensitizes lung adenocarcinoma to inhibitors of oxidative respiration and mTORC1 signaling.

SETD2 is a tumor suppressor that is frequently inactivated in several cancer types. The mechanisms through which SETD2 inactivation promotes cancer are unclear, and whether targetable vulnerabilities exist in these tumors is unknown. Here we identify heightened mTORC1-associated gene expression programs and functionally higher levels of oxidative metabolism and protein synthesis as prominent consequences of Setd2 inactivation in KRAS-driven mouse models of lung adenocarcinoma.

LKB1 drives stasis and C/EBP-mediated reprogramming to an alveolar type II fate in lung cancer.

LKB1 is among the most frequently altered tumor suppressors in lung adenocarcinoma. Inactivation of Lkb1 accelerates the growth and progression of oncogenic KRAS-driven lung tumors in mouse models. However, the molecular mechanisms by which LKB1 constrains lung tumorigenesis and whether the cancer state that stems from Lkb1 deficiency can be reverted remains unknown.

RB depletion is required for the continuous growth of tumors initiated by loss of RB.

The retinoblastoma (RB) tumor suppressor is functionally inactivated in a wide range of human tumors where this inactivation promotes tumorigenesis in part by allowing uncontrolled proliferation. RB has been extensively studied, but its mechanisms of action in normal and cancer cells remain only partly understood. Here, we describe a new mouse model to investigate the consequences of RB depletion and its re-activation in vivo.

LKB1 inactivation modulates chromatin accessibility to drive metastatic progression.

Metastasis is the leading cause of cancer-related deaths and enables cancer cells to compromise organ function by expanding in secondary sites. Since primary tumours and metastases often share the same constellation of driver mutations, the mechanisms that drive their distinct phenotypes are unclear. Here we show that inactivation of the frequently mutated tumour suppressor gene LKB1 (encoding liver kinase B1) has evolving effects throughout the progression of lung cancer, which leads to the differential epigenetic re-programming of early-stage primary tumours compared with late-stage metastases.

The p53 transcriptional response across tumor types reveals core and senescence-specific signatures modulated by long noncoding RNAs.

The p53 pathway is a universal tumor suppressor mechanism that limits tumor progression by triggering apoptosis or permanent cell cycle arrest, called senescence. In recent years, efforts to reactivate p53 function in cancer have proven to be a successful therapeutic strategy in murine models and have gained traction with the development of a range of small molecules targeting mutant p53. However, knowledge of the downstream mediators of p53 reactivation in different oncogenic contexts has been limited.

Mitochondrial apoptotic priming is a key determinant of cell fate upon p53 restoration.

Reactivation of p53 in established tumors typically results in one of two cell fates, cell cycle arrest or apoptosis, but it remains unclear how this cell fate is determined. We hypothesized that high mitochondrial priming prior to p53 reactivation would lead to apoptosis, while low priming would lead to survival and cell cycle arrest. Using a panel of Kras-driven, p53 restorable cell lines derived from genetically engineered mouse models of lung adenocarcinoma and sarcoma (both of which undergo cell cycle arrest upon p53 restoration), as well as lymphoma (which instead undergo apoptosis), we show that the level of mitochondrial apoptotic priming is a critical determinant of p53 reactivation outcome.

Reactivation of dormant tumor cells by modified lipids derived from stress-activated neutrophils.

Tumor recurrence years after seemingly successful treatment of primary tumors is one of the major causes of mortality in patients with cancer. Reactivation of dormant tumor cells is largely responsible for this phenomenon. Using dormancy models of lung and ovarian cancer, we found a specific mechanism, mediated by stress and neutrophils, that may govern this process.

PKC Is Required for KRAS-Driven Lung Tumorigenesis.

Non-small cell lung cancer (NSCLC) is the most frequent subtype of lung cancer and remains a highly lethal malignancy and one of the leading causes of cancer-related deaths worldwide. Mutant KRAS is the prevailing oncogenic driver of lung adenocarcinoma, the most common histologic form of NSCLC. In this study, we examined the role of PKCϵ, an oncogenic kinase highly expressed in NSCLC and other cancers, in KRAS-driven tumorigenesis.

Type 1 conventional dendritic cells are systemically dysregulated early in pancreatic carcinogenesis.

Type 1 conventional dendritic cells (cDC1s) are typically thought to be dysregulated secondarily to invasive cancer. Here, we report that cDC1 dysfunction instead develops in the earliest stages of preinvasive pancreatic intraepithelial neoplasia (PanIN) in the KrasLSL-G12D/+ Trp53LSL-R172H/+ Pdx1-Cre-driven (KPC) mouse model of pancreatic cancer. cDC1 dysfunction is systemic and progressive, driven by increased apoptosis, and results in suboptimal up-regulation of T cell-polarizing cytokines during cDC1 maturation.

Copper is an essential regulator of the autophagic kinases ULK1/2 to drive lung adenocarcinoma.

Although the transition metal copper (Cu) is an essential nutrient that is conventionally viewed as a static cofactor within enzyme active sites, a non-traditional role for Cu as a modulator of kinase signalling is emerging. Here, we found that Cu is required for the activity of the autophagic kinases ULK1 and ULK2 (ULK1/2) through a direct Cu-ULK1/2 interaction. Genetic loss of the Cu transporter Ctr1 or mutations in ULK1 that disrupt the binding of Cu reduced ULK1/2-dependent signalling and the formation of autophagosome complexes.

Blocking EGFR palmitoylation suppresses PI3K signaling and mutant KRAS lung tumorigenesis.

Non-small cell lung cancer (NSCLC) is often characterized by mutually exclusive mutations in the epidermal growth factor receptor (EGFR) or the guanosine triphosphatase KRAS. We hypothesized that blocking EGFR palmitoylation, previously shown to inhibit EGFR activity, might alter downstream signaling in the KRAS-mutant setting. Here, we found that blocking EGFR palmitoylation, by either knocking down the palmitoyltransferase DHHC20 or expressing a palmitoylation-resistant EGFR mutant, reduced activation of the kinase PI3K, the abundance of the transcription factor MYC, and the proliferation of cells in culture, as well as reduced tumor growth in a mouse model of KRAS-mutant lung adenocarcinoma.

RB constrains lineage fidelity and multiple stages of tumour progression and metastasis.

Mutations in the retinoblastoma (RB) tumour suppressor pathway are a hallmark of cancer and a prevalent feature of lung adenocarcinoma. Although RB was the first tumour suppressor to be identified, the molecular and cellular basis that underlies selection for persistent RB loss in cancer remains unclear. Methods that reactivate the RB pathway using inhibitors of cyclin-dependent kinases CDK4 and CDK6 are effective in some cancer types and are currently under evaluation for the treatment of lung adenocarcinoma.

Natural killer cells limit the clearance of senescent lung adenocarcinoma cells.

Senescence is an important p53-controlled tumor suppressor program that not only opposes the proliferation of cancer cells but also promotes their immune-mediated clearance in certain contexts. In hepatocellular cancer, p53 induction promotes an innate immune cell-mediated clearance of senescent cells wherein natural killer (NK) cells seem to play the primary sentinel role. Whether NK cells also surveil cancer cells in other tumor types when p53 is activated to promote a senescence response is unknown.

Off and back-on again: a tumor suppressor's tale.

Tumor suppressor genes play critical roles orchestrating anti-cancer programs that are both context dependent and mechanistically diverse. Beyond canonical tumor suppressive programs that control cell division, cell death, and genome stability, unexpected tumor suppressor gene activities that regulate metabolism, immune surveillance, the epigenetic landscape, and others have recently emerged. This diversity underscores the important roles these genes play in maintaining cellular homeostasis to suppress cancer initiation and progression, but also highlights a tremendous challenge in discerning precise context-specific programs of tumor suppression controlled by a given tumor suppressor.

Context-Dependent Effects of Amplified MAPK Signaling during Lung Adenocarcinoma Initiation and Progression.

Expression of oncogenic Kras initiates lung adenomas in a mitogen-activated protein kinase (MAPK) signal-dependent manner from only a subset of cell types in the adult mouse lung. Amplification of MAPK signaling is associated with progression to malignant adenocarcinomas, but whether this is a cause or a consequence of disease progression is not known. To better understand the effects of MAPK signaling downstream of Kras expression, we capitalized on the ability of Braf inhibition to selectively amplify MAPK pathway signaling in Kras-expressing epithelial cells.

Systematic Inactivation of Chromatin-Regulating Enzymes Identifies Setd2 as a Potent Tumor Suppressor in Lung Adenocarcinoma.

Chromatin-modifying genes are frequently mutated in human lung adenocarcinoma, but the functional impact of these mutations on disease initiation and progression is not well understood. Using a CRISPR-based approach, we systematically inactivated three of the most commonly mutated chromatin regulatory genes in two Kras-driven mouse models of lung adenocarcinoma to characterize the impact of their loss. Targeted inactivation of SWI/SNF nucleosome-remodeling complex members () or had complex effects on lung adenocarcinoma initiation and progression.

Recombinase-based conditional and reversible gene regulation via XTR alleles.

Synthetic biological tools that enable precise regulation of gene function within in vivo systems have enormous potential to discern gene function in diverse physiological settings. Here we report the development and characterization of a synthetic gene switch that, when targeted in the mouse germline, enables conditional inactivation, reports gene expression and allows inducible restoration of the targeted gene. Gene inactivation and reporter expression is achieved through Cre-mediated stable inversion of an integrated gene-trap reporter, whereas inducible gene restoration is afforded by Flp-dependent deletion of the inverted gene trap.

A versatile reporter system for CRISPR-mediated chromosomal rearrangements.

Although chromosomal deletions and inversions are important in cancer, conventional methods for detecting DNA rearrangements require laborious indirect assays. Here we develop fluorescent reporters to rapidly quantify CRISPR/Cas9-mediated deletions and inversions. We find that inversion depends on the non-homologous end-joining enzyme LIG4.

A conditional system to specifically link disruption of protein-coding function with reporter expression in mice.

Conditional gene deletion in mice has contributed immensely to our understanding of many biological and biomedical processes. Despite an increasing awareness of nonprotein-coding functional elements within protein-coding transcripts, current gene-targeting approaches typically involve simultaneous ablation of noncoding elements within targeted protein-coding genes. The potential for protein-coding genes to have additional noncoding functions necessitates the development of novel genetic tools capable of precisely interrogating individual functional elements.

Response and resistance to NF-κB inhibitors in mouse models of lung adenocarcinoma.

Unlabelled: Lung adenocarcinoma is a leading cause of cancer death worldwide. We recently showed that genetic inhibition of the NF-κB pathway affects both the initiation and the maintenance of lung cancer, identifying this pathway as a promising therapeutic target. In this investigation, we tested the efficacy of small-molecule NF-κB inhibitors in mouse models of lung cancer.