Targeting PDGF signaling of cancer-associated fibroblasts blocks feedback activation of HIF-1α and tumor progression of clear cell ovarian cancer.

Ovarian clear cell carcinoma (OCCC) is a gynecological cancer with a dismal prognosis; however, the mechanism underlying OCCC chemoresistance is not well understood. To explore the intracellular networks associated with the chemoresistance, we analyze surgical specimens by performing integrative analyses that combine single-cell analyses and spatial transcriptomics. We find that a chemoresistant OCCC subpopulation with elevated HIF activity localizes mainly in areas populated by cancer-associated fibroblasts (CAFs) with a myofibroblastic phenotype, which is corroborated by quantitative immunostaining. CAF-enhanced chemoresistance and HIF-1α induction are recapitulated in co-culture assays, which show that cancer-derived platelet-derived growth factor (PDGF) contributes to the chemoresistance and HIF-1α induction via PDGF receptor signaling in CAFs. Ripretinib is identified as an effective receptor tyrosine kinase inhibitor against CAF survival. In the co-culture system and xenograft tumors, ripretinib prevents CAF survival and suppresses OCCC proliferation in the presence of carboplatin, indicating that combination of conventional chemotherapy and CAF-targeted agents is effective against OCCC.

Predictive factors for postoperative delirium in thoracic surgery.

OBJECTIVE: We examined cases in which delirium developed after thoracic surgery under general anesthesia at our hospital to determine the predictive factors for postoperative delirium, as well as the perioperative findings in cases showing postoperative delirium. METHODS: This retrospective study included 1674 patients who underwent surgery under general anesthesia at our hospital between 2012 and 2022, A psychiatrist diagnosed postoperative delirium using the Confusion Assessment Method. RESULTS: There were 99 (5.9%) patients with postoperative delirium in our study, including 85 (86%) men, of whom 31 (31%) had a history of cerebrovascular disease. The incidence of postoperative delirium in patients aged > 80 years was 20% (36/182). The postoperative delirium group showed significantly longer hospital stays and more frequent postoperative complications than the group without postoperative delirium. In univariate analysis, age ≥ 80 years, male sex, history of cerebrovascular disease, hypertension, history of atrial fibrillation, and history of smoking were identified as significant factors, while multivariate analysis identified age ≥ 80 years, male sex, history of cerebrovascular disease, hypertension, and history of smoking as significant factors (odds ratios = 5.15, 2.04, 3.10, 1.67, and 2.36, respectively). In the 169 cases with none of these five factors, the postoperative delirium risk was 0% (0/169). CONCLUSIONS: In patients undergoing thoracic surgery, predictive factors for postoperative delirium include age ≥ 80 years, male sex, history of cerebrovascular disease, hypertension, and smoking history. The findings also indicate that patients with these risk factors may require psychiatric consultation before surgery.

Nrf2 alleviates spaceflight-induced immunosuppression and thrombotic microangiopathy in mice.

Spaceflight-related stresses impact health via various body systems, including the haematopoietic and immune systems, with effects ranging from moderate alterations of homoeostasis to serious illness. Oxidative stress appears to be involved in these changes, and the transcription factor Nrf2, which regulates expression of a set of cytoprotective and antioxidative stress response genes, has been implicated in the response to spaceflight-induced stresses. Here, we show through analyses of mice from the MHU-3 project, in which Nrf2-knockout mice travelled in space for 31 days, that mice lacking Nrf2 suffer more seriously from spaceflight-induced immunosuppression than wild-type mice. We discovered that a one-month spaceflight-triggered the expression of tissue inflammatory marker genes in wild-type mice, an effect that was even more pronounced in the absence of Nrf2. Concomitant with induction of inflammatory conditions, the consumption of coagulation-fibrinolytic factors and platelets was elevated by spaceflight and further accelerated by Nrf2 deficiency. These results highlight that Nrf2 mitigates spaceflight-induced inflammation, subsequent immunosuppression, and thrombotic microangiopathy. These observations reveal a new strategy to relieve health problems encountered during spaceflight.

Hypolipidemic and Anti-Inflammatory Effects of Curcuma longa-Derived Bisacurone in High-Fat Diet-Fed Mice.

Turmeric (Curcuma longa) contains various compounds that potentially improve health. Bisacurone is a turmeric-derived compound but has been less studied compared to other compounds, such as curcumin. In this study, we aimed to evaluate the anti-inflammatory and lipid-lowering effects of bisacurone in high-fat diet (HFD)-fed mice. Mice were fed HFD to induce lipidemia and orally administered bisacurone daily for two weeks. Bisacurone reduced liver weight, serum cholesterol and triglyceride levels, and blood viscosity in mice. Splenocytes from bisacurone-treated mice produced lower levels of the pro-inflammatory cytokines IL-6 and TNF-α upon stimulation with a toll-like receptor (TLR) 4 ligand, lipopolysaccharide (LPS), and TLR1/2 ligand, Pam3CSK4, than those from untreated mice. Bisacurone also inhibited LPS-induced IL-6 and TNF-α production in the murine macrophage cell line, RAW264.7. Western blot analysis revealed that bisacurone inhibited the phosphorylation of IKKα/ß and NF-κB p65 subunit, but not of the mitogen-activated protein kinases, p38 kinase and p42/44 kinases, and c-Jun N-terminal kinase in the cells. Collectively, these results suggest that bisacurone has the potential to reduce serum lipid levels and blood viscosity in mice with high-fat diet-induced lipidemia and modulate inflammation via inhibition of NF-κB-mediated pathways.

Co-Clinical Study of [fam-] Trastuzumab Deruxtecan (DS8201a) in Patient-Derived Xenograft Models of Uterine Carcinosarcoma and Its Association with Clinical Efficacy.

PURPOSE: Uterine carcinosarcoma (UCS), a subtype of endometrial carcinoma, is a rare and aggressive cancer with a poor prognosis. High clinical efficacy of trastuzumab deruxtecan (T-DXd) in HER2-expressing UCS was recently reported in a phase II trial (STATICE trial). We performed a co-clinical study of T-DXd using patient-derived xenograft (PDX) models of participants in the STATICE trial. EXPERIMENTAL DESIGN: Tumor specimens were resected during primary surgery or biopsied at recurrence from patients with UCS and transplanted into immunodeficient mice. Seven UCS-PDXs from six patients were established and HER2, estrogen receptor (ER), and p53 expression in PDX and the original tumor was assessed. Drug efficacy tests were performed using six of the seven PDXs. Of the six UCS-PDXs tested, two were derived from patients enrolled in the STATICE trial. RESULTS: The histopathological characteristics of the six PDXs were well-conserved from the original tumors. HER2 expression was 1+ in all PDXs, and ER and p53 expression was almost similar to that in the original tumors. Remarkable tumor shrinkage after T-DXd administration was observed in four of the six PDXs (67%), comparable with the response rate (70%) of HER2 1+ patients in the STATICE trial. Two patients enrolled in the STATICE trial showed partial response as the best response, and the clinical effect was well-replicated with marked tumor shrinkage. CONCLUSIONS: We successfully performed a co-clinical study of T-DXd in HER2-expressing UCS, along with the STATICE trial. Our PDX models can predict clinical efficacy and serve as an effective preclinical evaluation platform.

Selective Elimination of NRF2-Activated Cells by Competition With Neighboring Cells in the Esophageal Epithelium.

BACKGROUND & AIMS: NF-E2-related factor 2 (NRF2) is a transcription factor that regulates cytoprotective gene expression in response to oxidative and electrophilic stresses. NRF2 activity is mainly controlled by Kelch-like ECH-associated protein 1 (KEAP1). Constitutive NRF2 activation by NRF2 mutations or KEAP1 dysfunction results in a poor prognosis for esophageal squamous cell carcinoma (ESCC) through the activation of cytoprotective functions. However, the detailed contributions of NRF2 to ESCC initiation or promotion have not been clarified. Here, we investigated the fate of NRF2-activated cells in the esophageal epithelium. METHODS: We generated tamoxifen-inducible, squamous epithelium-specific Keap1 conditional knockout (Keap1-cKO) mice in which NRF2 was inducibly activated in a subset of cells at the adult stage. Histologic, quantitative reverse-transcription polymerase chain reaction, single-cell RNA-sequencing, and carcinogen experiments were conducted to analyze the Keap1-cKO esophagus. RESULTS: KEAP1-deleted/NRF2-activated cells and cells with normal NRF2 expression (KEAP1-normal cells) coexisted in the Keap1-cKO esophageal epithelium in approximately equal numbers, and NRF2-activated cells formed dysplastic lesions. NRF2-activated cells exhibited weaker attachment to the basement membrane and gradually disappeared from the epithelium. In contrast, neighboring KEAP1-normal cells exhibited accelerated proliferation and started dominating the epithelium but accumulated DNA damage that triggered carcinogenesis upon carcinogen exposure. CONCLUSIONS: Constitutive NRF2 activation promotes the selective elimination of epithelial cells via cell competition, but this competition induces DNA damage in neighboring KEAP1-normal cells, which predisposes them to chemical-induced ESCC.

The ß-TrCP-Mediated Pathway Cooperates with the Keap1-Mediated Pathway in Nrf2 Degradation In Vivo.

Nrf2 activates cytoprotective gene expression, and Nrf2 activity is regulated through at least two protein degradation pathways: the Keap1-mediated and ß-TrCP-mediated pathways. To address the relative contributions of these pathways, we generated knock-in mouse lines expressing an Nrf2SA mutant that harbored two substitution mutations of serine residues interacting with ß-TrCP. The homozygous (Nrf2SA/SA) mice grew normally, with Nrf2 levels comparable to those of wild-type (WT) mice under unstressed conditions. However, when Keap1 activity was suppressed, high levels of Nrf2 accumulated in Nrf2SA/SA macrophages compared with that in WT macrophages. We crossed Nrf2SA/SA mice with mice in which Keap1 was knocked down to two different levels. We found that the Nrf2SA/SA mutation induced higher Nrf2 activity when the Keap1 level was strongly reduced, and these mice showed severe growth retardation. However, activation and growth retardation were not evident when Keap1 was moderately suppressed. These increases in Nrf2 activity induced by the Nrf2SA mutation caused severe hyperplasia and hyperkeratosis in the esophageal epithelium but did not cause abnormalities in the other tissues/organs examined. These results indicate that the ß-TrCP-mediated pathway cooperates with the Keap1-mediated pathway to regulate Nrf2 activity, which is apparent when the Keap1-mediated pathway is profoundly suppressed.

Halofuginone micelle nanoparticles eradicate Nrf2-activated lung adenocarcinoma without systemic toxicity.

The Keap1-Nrf2 system is the master regulator of the cellular response against oxidative and xenobiotic stresses. Constitutive activation of Nrf2 is frequently observed in various types of cancers. Nrf2 hyperactivation induces metabolic reprogramming in cancer cells, which supports the increased energy demand required for rapid proliferation and confers high-level resistance against anticancer radio/chemotherapy. Hence, Nrf2 inhibition has emerged as an attractive therapeutic strategy to counter such acquired resistance in Nrf2-activated tumors. We previously identified Halofuginone (HF) as a promising Nrf2 inhibitor. In this study, we pursued preclinical characterization of HF and found that while HF markedly reduced the viability of cancer cells, it also caused severe hematopoietic and immune cell suppression in a dose-dependent manner. Hence, to overcome this toxicity, we decided to employ a nanomedicine approach to HF. We found that encapsulation of HF into a polymeric micelle (HF micelle; HFm) largely relieved the systemic toxicity exhibited by free HF while maintaining the tumor-suppressive properties of HF. LC-MS/MS analysis revealed that the reduction in the magnitude of adverse effects was the result of the ability to release HF from the HFm core in a slow and sustained manner. These results thus support the contention that HFm will potentially counteract Nrf2-activated cancers in the clinical settings.

Multifaceted Roles of the KEAP1-NRF2 System in Cancer and Inflammatory Disease Milieu.

In a multicellular environment, many different types of cells interact with each other. The KEAP1-NRF2 system defends against electrophilic and oxidative stresses in various types of cells. However, the KEAP1-NRF2 system also regulates the expression of genes involved in cell proliferation and inflammation, indicating that the system plays cell type-specific roles. In this review, we introduce the multifarious roles of the KEAP1-NRF2 system in various types of cells, especially focusing on cancer and inflammatory diseases. Cancer cells frequently hijack the KEAP1-NRF2 system, and NRF2 activation confers cancer cells with a proliferative advantage and therapeutic resistance. In contrast, the activation of NRF2 in immune cells, especially in myeloid cells, suppresses tumor development. In chronic inflammatory diseases, such as sickle cell disease, NRF2 activation in myeloid and endothelial cells represses the expression of proinflammatory cytokine and adherent molecule genes, mitigating inflammation and organ damage. Based on these cell-specific roles played by the KEAP1-NRF2 system, NRF2 inducers have been utilized for the treatment of inflammatory diseases. In addition, the use of NRF2 inducers and/or inhibitors with canonical antineoplastic drugs is an emerging approach to cancer treatment.

Gene expression changes related to bone mineralization, blood pressure and lipid metabolism in mouse kidneys after space travel.

Space travel burdens health by imposing considerable environmental stress associated with radioactivity and microgravity. In particular, gravity change predominantly impacts blood pressure and bone homeostasis, both of which are controlled mainly by the kidneys. Nuclear factor erythroid-2-related transcription factor 2 (Nrf2) plays essential roles in protecting the kidneys from various environmental stresses and injuries. To elucidate the effects of space travel on mammals in preparation for the upcoming space era, our study investigated the contribution of Nrf2 to kidney function in mice two days after their return from a 31-day stay in the International Space Station using Nrf2 knockout mice. Meaningfully, expression levels of genes regulating bone mineralization, blood pressure and lipid metabolism were found to be significantly altered in the kidneys after space travel in an Nrf2-independent manner. In particular, uridine diphosphate-glucuronosyltransferase 1A (Ugt1a) isoform genes were found to be expressed in an Nrf2-dependent manner and induced exclusively in the kidneys after return to Earth. Since spaceflight elevated the concentrations of fatty acids in the mouse plasma, we suggest that Ugt1a isoform expression in the kidneys was induced to promote glucuronidation of excessively accumulated lipids and excrete them into urine after the return from space. Thus, the kidneys were proven to play central roles in adaptation to gravity changes caused by going to and returning from space by controlling blood pressure and bone mineralization. Additionally, kidney Ugt1a isoform induction after space travel implies a significant role of the kidneys for space travelers in the excretion of excessive lipids.

Comparative Study on the Efficacy and Exposure of Molecular Target Agents in Non-small Cell Lung Cancer PDX Models with Driver Genetic Alterations.

Patient-derived xenografts (PDX) can adequately reflect clinical drug efficacy. However, the methods for evaluating drug efficacy are not fully established. We selected five non-small cell lung cancer (NSCLC) PDXs with genetic alterations from established PDXs and the corresponding molecular targeted therapy was administered orally for 21 consecutive days. Genetic analysis, measurement of drug concentrations in blood and tumors using LC/MS-MS, and analysis of drug distribution in tumors using matrix-assisted laser desorption/ionization mass spectrometry were performed. Fifteen (20%) PDXs were established using samples collected from 76 patients with NSCLC with genetic alterations. The genetic alterations observed in original patients were largely maintained in PDXs. We compared the drug efficacy in original patients and PDX models; the efficacies against certain PDXs correlated with the clinical effects, while those against the others did not. We determined blood and intratumor concentrations in the PDX model, but both concentrations were low, and no evident correlation with the drug efficacy could be observed. The intratumoral spatial distribution of the drugs was both homogeneous and heterogeneous for each drug, and the distribution was independent of the expression of the target protein. The evaluation of drug efficacy in PDXs enabled partial reproduction of the therapeutic effect in original patients. A more detailed analysis of systemic and intratumoral pharmacokinetics may help clarify the mode of action of drugs. Further development of evaluation methods and indices to improve the prediction accuracy of clinical efficacy is warranted.

Nrf2 plays a critical role in the metabolic response during and after spaceflight.

Space travel induces stresses that contribute to health problems, as well as inducing the expression of Nrf2 (NF-E2-related factor-2) target genes that mediate adaptive responses to oxidative and other stress responses. The volume of epididymal white adipose tissue (eWAT) in mice increases during spaceflight, a change that is attenuated by Nrf2 knockout. We conducted metabolome analyses of plasma from wild-type and Nrf2 knockout mice collected at pre-flight, in-flight and post-flight time points, as well as tissues collected post-flight to clarify the metabolic responses during and after spaceflight and the contribution of Nrf2 to these responses. Plasma glycerophospholipid and sphingolipid levels were elevated during spaceflight, whereas triacylglycerol levels were lower after spaceflight. In wild-type mouse eWAT, triacylglycerol levels were increased, but phosphatidylcholine levels were decreased, and these changes were attenuated in Nrf2 knockout mice. Transcriptome analyses revealed marked changes in the expression of lipid-related genes in the liver and eWAT after spaceflight and the effects of Nrf2 knockout on these changes. Based on these results, we concluded that space stress provokes significant responses in lipid metabolism during and after spaceflight; Nrf2 plays critical roles in these responses.

NRF3 upregulates gene expression in SREBP2-dependent mevalonate pathway with cholesterol uptake and lipogenesis inhibition.

Lipids, such as cholesterol and fatty acids, influence cell signaling, energy storage, and membrane formation. Cholesterol is biosynthesized through the mevalonate pathway, and aberrant metabolism causes metabolic diseases. The genetic association of a transcription factor NRF3 with obesity has been suggested, although the molecular mechanisms remain unknown. Here, we show that NRF3 upregulates gene expression in SREBP2-dependent mevalonate pathway. We further reveal that NRF3 overexpression not only reduces lanosterol, a cholesterol precursor, but also induces the expression of the GGPS1 gene encoding an enzyme in the production of GGPP from farnesyl pyrophosphate (FPP), a lanosterol precursor. NRF3 overexpression also enhances cholesterol uptake through RAB5-mediated macropinocytosis process, a bulk and fluid-phase endocytosis pathway. Moreover, we find that GGPP treatment abolishes NRF3 knockdown-mediated increase of neutral lipids. These results reveal the potential roles of NRF3 in the SREBP2-dependent mevalonate pathway for cholesterol uptake through macropinocytosis induction and for lipogenesis inhibition through GGPP production.

Visualization of Intratumor Pharmacokinetics of [fam-] Trastuzumab Deruxtecan (DS-8201a) in HER2 Heterogeneous Model Using Phosphor-integrated Dots Imaging Analysis.

PURPOSE: We assessed the intratumor pharmacokinetics of [fam-] trastuzumab deruxtecan, T-DXd (known as DS-8201a), a novel HER2-targeted antibody-drug conjugate, using phosphor-integrated dots (PID)-imaging analysis to elucidate its pharmacologic mechanism. EXPERIMENTAL DESIGN: We used two mouse xenograft models administered T-DXd at the concentration of 4 mg/kg: (i) a heterogeneous model in which HER2-positive and HER2-negative cell lines were mixed, and (ii) a homogeneous model in which both cell types were transplanted separately into the same mouse. PID imaging involved immunostaining using novel high-intensity fluorescent nanoparticles. The distribution of T-DXd was assessed by PID imaging targeting the parent antibody, trastuzumab, and the payload, DXd, in serial frozen sections, respectively. RESULTS: After T-DXd administration in the heterogeneous model, HER2 expression tended to decrease in a time-dependent manner. The distribution of trastuzumab and DXd was observed by PID imaging along the HER2-positive area throughout the observation period. A detailed comparison of the PID distribution between trastuzumab and DXd showed that trastuzumab matched almost perfectly with the HER2-positive area. In contrast, DXd exhibited widespread distribution in the surrounding HER2-negative area as well. In the HER2-negative tumor of the homogeneous model, the PID distribution of trastuzumab and DXd remained extremely low throughout the observation period. CONCLUSIONS: Our results suggest that T-DXd is distributed to tumor tissues via trastuzumab in a HER2-dependent manner and then to adjacent HER2-negative areas. We successfully visualized the intratumor distribution of T-DXd and its mechanism of action, the so-called "bystander effect."

Characterization of the large-scale Japanese patient-derived xenograft (J-PDX) library.

The use of patient-derived xenografts (PDXs) has recently attracted attention as a drug discovery platform with a high predictive clinical efficacy and a preserved tumor heterogeneity. Given the racial differences in genetic variations, it would be desirable to establish a PDX library from Japanese cancer patients on a large scale. We thus tried to construct the Japanese PDX (J-PDX) library with a detailed clinical information for further clinical utilization. Between August 2018 and May 2020, a total of 1126 cancer specimens from 1079 patients were obtained at the National Cancer Center Hospital and National Cancer Center Hospital East, Japan, and were immediately transplanted to immunodeficient mice at the National Cancer Center Research Institute. A total of 298 cross-cancer PDXs were successfully established. The time to engraftment varied greatly by cancer subtypes, especially in the first passage. The engraftment rate was strongly affected by the clinical stage and survival time of the original patients. Approximately 1 year was needed from tumor collection to the time when coclinical trials were conducted to test the clinical utility. The 1-year survival rates of the patients who were involved in establishing the PDX differed significantly, from 95.6% for colorectal cancer to 56.3% for lung cancer. The J-PDX library consisting of a wide range of cancer subtypes has been successfully established as a platform for drug discovery and development in Japan. When conducting coclinical trials, it is necessary to consider the target cancer type, stage, and engraftment rate in light of this report.

Cellular Nrf2 Levels Determine Cell Fate during Chemical Carcinogenesis in Esophageal Epithelium.

Nrf2 is essential for cytoprotection against carcinogens, and through systemic Nrf2 knockout mice, Nrf2-deficient cells were shown to be susceptible to chemical carcinogens and prone to developing cancers. However, the oncogenic potential of Nrf2-deficient epithelial cells surrounded by normal cells in the esophagus could not be assessed by previous models, and the fate of Nrf2-deficient cells in such situations remains elusive. In this study, therefore, we generated mice that harbor almost equal levels of cells with Nrf2 deleted and those with Nrf2 intact in the basal layer of the esophageal epithelium, utilizing inducible Cre-mediated recombination of Nrf2 alleles in adults through moderate use of tamoxifen. In this mouse model, epithelial cells with Nrf2 deleted were maintained with no obvious decrease or phenotypic changes for 12 weeks under unstressed conditions. Upon exposure to the carcinogen 4-nitroquinoline-1-oxide (4NQO), the cells with Nrf2 deleted accumulated DNA damage and selectively disappeared from the epithelium, so almost all 4NQO-induced tumors originated from cells with Nrf2 intact and not from those with Nrf2 deleted. We propose that cells with Nrf2 deleted do not undergo carcinogenesis due to selective elimination upon exposure to 4NQO, indicating that cellular Nrf2 abundance and the epithelial environment determine the cell fate or oncogenic potential of esophageal epithelial cells in 4NQO-induced carcinogenesis.

Author Correction: Nrf2 contributes to the weight gain of mice during space travel.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Nrf2 contributes to the weight gain of mice during space travel.

Space flight produces an extreme environment with unique stressors, but little is known about how our body responds to these stresses. While there are many intractable limitations for in-flight space research, some can be overcome by utilizing gene knockout-disease model mice. Here, we report how deletion of Nrf2, a master regulator of stress defense pathways, affects the health of mice transported for a stay in the International Space Station (ISS). After 31 days in the ISS, all flight mice returned safely to Earth. Transcriptome and metabolome analyses revealed that the stresses of space travel evoked ageing-like changes of plasma metabolites and activated the Nrf2 signaling pathway. Especially, Nrf2 was found to be important for maintaining homeostasis of white adipose tissues. This study opens approaches for future space research utilizing murine gene knockout-disease models, and provides insights into mitigating space-induced stresses that limit the further exploration of space by humans.

Microenvironmental Activation of Nrf2 Restricts the Progression of Nrf2-Activated Malignant Tumors.

The transcription factor Nrf2 activates transcription of cytoprotective genes during oxidative and electrophilic insults. Nrf2 activity is regulated by Keap1 in a stress-dependent manner in normal cells, and somatic loss-of-function mutations of Keap1 are known to induce constitutive Nrf2 activation, especially in lung adenocarcinomas, conferring survival and proliferative benefits to tumors. Therefore, several therapeutic strategies that aim to inhibit Nrf2 in tumors have been developed for the treatment of Nrf2-activated cancers. Here we addressed whether targeting Nrf2 activation in the microenvironment can suppress the progression of Nrf2-activated tumors. We combined two types of Keap1-flox mice expressing variable levels of Keap1 with a Kras-driven adenocarcinoma model to generate Keap1-deficient lung tumors surrounded by normal or Keap1-knockdown host cells. In this model system, activation of Nrf2 in the microenvironment prolonged the survival of Nrf2-activated tumor-bearing mice. The Nrf2-activated microenvironment suppressed tumor burden; in particular, preinvasive lesion formation was significantly suppressed. Notably, loss of Nrf2 in bone marrow-derived cells in Nrf2-activated host cells appeared to counteract the suppression of Nrf2-activated cancer progression. Thus, these results demonstrate that microenvironmental Nrf2 activation suppresses the progression of malignant Nrf2-activated tumors and that Nrf2 activation in immune cells at least partially contributes to these suppressive effects. SIGNIFICANCE: This study clarifies the importance of Nrf2 activation in the tumor microenvironment and in the host for the suppression of malignant Nrf2-activated cancers and proposes new cancer therapies utilizing inducers of Nrf2.

EVI1 and GATA2 misexpression induced by inv(3)(q21q26) contribute to megakaryocyte-lineage skewing and leukemogenesis.

Chromosomal rearrangements between 3q21 and 3q26 elicit high-risk acute myeloid leukemia (AML), which is often associated with elevated platelet and megakaryocyte (Mk) numbers. The 3q rearrangements reposition a GATA2 enhancer near the EVI1 (or MECOM) locus, which results in both EVI1 overexpression and GATA2 haploinsufficiency. However, the mechanisms explaining how the misexpression of these 2 genes individually contribute to leukemogenesis are unknown. To clarify the characteristics of differentiation defects caused by EVI1 and GATA2 misexpression and to identify the cellular origin of leukemic cells, we generated a system to monitor both inv(3) allele-driven EVI1 and Gata2 expression in 3q-rearranged AML model mice. A cell population in which both EVI1 and Gata2 were highly induced appeared in the bone marrows before the onset of frank leukemia. This population had acquired serial colony-forming potential. Because hematopoietic stem/progenitor cells (HSPCs) and Mks were enriched in this peculiar population, we analyzed the independent EVI1 and GATA2 contributions to HSPC and Mk. We found that inv(3)-driven EVI1 promotes accumulation of Mk-biased and myeloid-biased progenitors, Mks, and platelets, and that Gata2 heterozygous deletion enhanced Mk-lineage skewing of EVI1-expressing progenitors. Notably, inv(3)-directed EVI1 expression and Gata2 haploinsufficient expression cooperatively provoke a leukemia characterized by abundant Mks and platelets. These hematological features of the mouse model phenocopy those observed in human 3q AML. On the basis of these results, we conclude that inv(3)-driven EVI1 expression in HSPCs and Mks collaborates with Gata2 haploinsufficiency to provoke Mk-lineage skewing and leukemogenesis with excessive platelets, thus mimicking an important feature of human AML.