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Identifying metabolic steps that are specifically required for the survival of cancer cells but are dispensable in normal cells remains a challenge1. Here we report a therapeutic vulnerability in a sugar nucleotide biosynthetic pathway that can be exploited in cancer cells with only a limited impact on normal cells. A systematic examination of conditionally essential metabolic enzymes revealed that UXS1, a Golgi enzyme that converts one sugar nucleotide (UDP-glucuronic acid, UDPGA) to another (UDP-xylose), is essential only in cells that express high levels of the enzyme immediately upstream of it, UGDH. This conditional relationship exists because UXS1 is required to prevent excess accumulation of UDPGA, which is produced by UGDH. UXS1 not only clears away UDPGA but also limits its production through negative feedback on UGDH. Excess UDPGA disrupts Golgi morphology and function, which impedes the trafficking of surface receptors such as EGFR to the plasma membrane and diminishes the signalling capacity of cells. UGDH expression is elevated in several cancers, including lung adenocarcinoma, and is further enhanced during chemoresistant selection. As a result, these cancer cells are selectively dependent on UXS1 for UDPGA detoxification, revealing a potential weakness in tumours with high levels of UGDH.
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Neoplasias , Uridina Difosfato Ácido Glucurónico , Humanos , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Neoplasias/patología , Transducción de Señal , Uridina Difosfato Ácido Glucurónico/biosíntesis , Uridina Difosfato Ácido Glucurónico/metabolismo , Uridina Difosfato Xilosa/biosíntesis , Uridina Difosfato Xilosa/metabolismo , Adenocarcinoma del Pulmón , Neoplasias PulmonaresRESUMEN
BACKGROUND: Atypical breast hyperplasias (AH) have a 10-year risk of progression to invasive cancer estimated at 4-7%, with the overall risk of developing breast cancer increased by ~ 4-fold. AH lesions are estrogen receptor alpha positive (ERα+) and represent risk indicators and/or precursor lesions to low grade ERα+ tumors. Therefore, molecular profiles of AH lesions offer insights into the earliest changes in the breast epithelium, rendering it susceptible to oncogenic transformation. METHODS: In this study, women were selected who were diagnosed with ductal or lobular AH, but no breast cancer prior to or within the 2-year follow-up. Paired AH and histologically normal benign (HNB) tissues from patients were microdissected. RNA was isolated, amplified linearly, labeled, and hybridized to whole transcriptome microarrays to determine gene expression profiles. Genes that were differentially expressed between AH and HNB were identified using a paired analysis. Gene expression signatures distinguishing AH and HNB were defined using AGNES and PAM methods. Regulation of gene networks was investigated using breast epithelial cell lines, explant cultures of normal breast tissue and mouse tissues. RESULTS: A 99-gene signature discriminated the histologically normal and AH tissues in 81% of the cases. Network analysis identified coordinated alterations in signaling through ERα, epidermal growth factor receptors, and androgen receptor which were associated with the development of both lobular and ductal AH. Decreased expression of SFRP1 was also consistently lower in AH. Knockdown of SFRP1 in 76N-Tert cells resulted altered expression of 13 genes similarly to that observed in AH. An SFRP1-regulated network was also observed in tissues from mice lacking Sfrp1. Re-expression of SFRP1 in MCF7 cells provided further support for the SFRP1-regulated network. Treatment of breast explant cultures with rSFRP1 dampened estrogen-induced progesterone receptor levels. CONCLUSIONS: The alterations in gene expression were observed in both ductal and lobular AH suggesting shared underlying mechanisms predisposing to AH. Loss of SFRP1 expression is a significant regulator of AH transcriptional profiles driving previously unidentified changes affecting responses to estrogen and possibly other pathways. The gene signature and pathways provide insights into alterations contributing to AH breast lesions.
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Regulación de la Expresión Génica , Péptidos y Proteínas de Señalización Intercelular/genética , Glándulas Mamarias Humanas/metabolismo , Glándulas Mamarias Humanas/patología , Proteínas de la Membrana/genética , Transcriptoma , Adulto , Animales , Biomarcadores , Biomarcadores de Tumor , Neoplasias de la Mama/etiología , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Femenino , Perfilación de la Expresión Génica , Redes Reguladoras de Genes , Humanos , Hiperplasia , Ratones , Ratones Noqueados , Persona de Mediana Edad , Transducción de SeñalAsunto(s)
COVID-19/diagnóstico , Huésped Inmunocomprometido , Trasplante de Hígado , Reinfección , COVID-19/virología , Prueba de Ácido Nucleico para COVID-19 , Humanos , Inmunosupresores , Masculino , Persona de Mediana Edad , Ácido Micofenólico/uso terapéutico , Filogenia , SARS-CoV-2/genética , Tacrolimus/uso terapéuticoRESUMEN
Breast cancers that are "triple-negative" for the clinical markers ESR1, PGR, and HER2 typically belong to the Basal-like molecular subtype. Defective Rb, p53, and Brca1 pathways are each associated with triple-negative and Basal-like subtypes. Our mouse genetic studies demonstrate that the combined inactivation of Rb and p53 pathways is sufficient to suppress the physiological cell death of mammary involution. Furthermore, concomitant inactivation of all three pathways in mammary epithelium has an additive effect on tumor latency and predisposes highly penetrant, metastatic adenocarcinomas. The tumors are poorly differentiated and have histologic features that are common among human Brca1-mutated tumors, including heterogeneous morphology, metaplasia, and necrosis. Gene expression analyses demonstrate that the tumors share attributes of both Basal-like and Claudin-low signatures, two molecular subtypes encompassed by the broader, triple-negative class defined by clinical markers.
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Proteína BRCA1 , Neoplasias de la Mama , Proteína de Retinoblastoma , Proteína p53 Supresora de Tumor , Animales , Apoptosis , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Receptor alfa de Estrógeno/genética , Receptor alfa de Estrógeno/metabolismo , Evolución Molecular , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Glándulas Mamarias Animales/metabolismo , Glándulas Mamarias Animales/patología , Redes y Vías Metabólicas , Ratones , Receptor ErbB-2/genética , Receptor ErbB-2/metabolismo , Receptores de Progesterona/genética , Receptores de Progesterona/metabolismo , Proteína de Retinoblastoma/genética , Proteína de Retinoblastoma/metabolismo , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Pancreatic ductal adenocarcinoma (PDAC), one of the most aggressive human malignancies, is thought to be initiated by KRAS activation. Here we find that transcriptional activation mediated by the Gli family of transcription factors, although dispensable for pancreatic development, is required for Kras-induced proliferation and survival in primary pancreatic epithelial cells in culture and for Kras-driven pancreatic intraepithelial neoplasia and PDAC formation in vivo. Further, ectopic Gli1 activation in the mouse pancreas accelerates Kras-driven tumor formation, underscoring the importance of Gli transcription factors in pancreatic tumorigenesis. Interestingly, we demonstrate Gli-regulated I-kappa-B kinase epsilon (IKBKE) and NF-κB activity in pancreatic cancer cells and show that this activity is a critical downstream mediator for Gli-dependent PDAC cell transformation and survival. Together, these studies demonstrate the requirement for Gli in Kras-dependent pancreatic epithelial transformation, suggest a mechanism of Gli-NF-κB oncogenic activation, and provide genetic evidence supporting the therapeutic targeting of Gli activity in pancreatic cancer.
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Carcinoma Ductal Pancreático/genética , Genes ras , Neoplasias Pancreáticas/genética , Factores de Transcripción/metabolismo , Animales , Carcinoma Ductal Pancreático/patología , Proliferación Celular , Proteínas I-kappa B/metabolismo , Ratones , FN-kappa B/metabolismo , Neoplasias Pancreáticas/patología , Proteínas Proto-Oncogénicas/metabolismoRESUMEN
Endoplasmic reticulum to mitochondria Ca2+ transfer is important for cancer cell survival, but the role of mitochondrial Ca2+ uptake through the mitochondrial Ca2+ uniporter (MCU) in pancreatic adenocarcinoma (PDAC) is poorly understood. Here, we show that increased MCU expression is associated with malignancy and poorer outcomes in PDAC patients. In isogenic murine PDAC models, Mcu deletion (Mcu KO) ablated mitochondrial Ca2+ uptake, which reduced proliferation and inhibited self-renewal. Orthotopic implantation of MCU-null tumor cells reduced primary tumor growth and metastasis. Mcu deletion reduced the cellular plasticity of tumor cells by inhibiting epithelial-to-mesenchymal transition (EMT), which contributes to metastatic competency in PDAC. Mechanistically, the loss of mitochondrial Ca2+ uptake reduced expression of the key EMT transcription factor Snail and secretion of the EMT-inducing ligand TGFß. Snail re-expression and TGFß treatment rescued deficits in Mcu KO cells and restored their metastatic ability. Thus, MCU may present a therapeutic target in PDAC to limit cancer-cell-induced EMT and metastasis.
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Patients with castration-resistant prostate cancer (CRPC) are generally unresponsive to tumor targeted and immunotherapies. Whether genetic alterations acquired during the evolution of CRPC impact immune and immunotherapy responses is largely unknown. Using our innovative electroporation-based mouse models, we generated distinct genetic subtypes of CRPC found in patients and uncovered unique immune microenvironments. Specifically, mouse and human prostate tumors with MYC amplification and p53 disruption had weak cytotoxic lymphocyte infiltration and an overall dismal prognosis. MYC and p53 cooperated to induce tumor intrinsic secretion of VEGF, which by signaling through VEGFR2 expressed on CD8+ T cells, could directly inhibit T cell activity. Targeting VEGF-VEGFR2 signaling in vivo led to CD8+ T cell-mediated tumor and metastasis growth suppression and significantly increased overall survival in MYC and p53 altered CPRC. VEGFR2 blockade also led to induction of PD-L1, and in combination with PD-L1 immune checkpoint blockade produced anti-tumor efficacy in multiple preclinical CRPC mouse models. Thus, our results identify a genetic mechanism of immune suppression through VEGF signaling in prostate cancer that can be targeted to reactivate immune and immunotherapy responses in an aggressive subtype of CRPC. Significance: Though immune checkpoint blockade (ICB) therapies can achieve curative responses in many treatment-refractory cancers, they have limited efficacy in CRPC. Here we identify a genetic mechanism by which VEGF contributes to T cell suppression, and demonstrate that VEGFR2 blockade can potentiate the effects of PD-L1 ICB to immunologically treat CRPC.
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CD24 is frequently overexpressed in ovarian cancer and promotes immune evasion by interacting with its receptor Siglec10, present on tumor-associated macrophages, providing a "don't eat me" signal that prevents targeting and phagocytosis by macrophages. Factors promoting CD24 expression could represent novel immunotherapeutic targets for ovarian cancer. Here, using a genome-wide CRISPR knockout screen, we identify GPAA1 (glycosylphosphatidylinositol anchor attachment 1), a factor that catalyzes the attachment of a glycosylphosphatidylinositol (GPI) lipid anchor to substrate proteins, as a positive regulator of CD24 cell surface expression. Genetic ablation of GPAA1 abolishes CD24 cell surface expression, enhances macrophage-mediated phagocytosis, and inhibits ovarian tumor growth in mice. GPAA1 shares structural similarities with aminopeptidases. Consequently, we show that bestatin, a clinically advanced aminopeptidase inhibitor, binds to GPAA1 and blocks GPI attachment, resulting in reduced CD24 cell surface expression, increased macrophage-mediated phagocytosis, and suppressed growth of ovarian tumors. Our study highlights the potential of targeting GPAA1 as an immunotherapeutic approach for CD24+ ovarian cancers.
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Aciltransferasas , Antígeno CD24 , Neoplasias Ováricas , Fagocitosis , Animales , Femenino , Humanos , Ratones , Aciltransferasas/metabolismo , Amidohidrolasas/metabolismo , Amidohidrolasas/genética , Antígeno CD24/metabolismo , Línea Celular Tumoral , Glicosilfosfatidilinositoles/metabolismo , Macrófagos/metabolismo , Macrófagos/inmunología , Neoplasias Ováricas/inmunología , Neoplasias Ováricas/metabolismo , Neoplasias Ováricas/patología , Neoplasias Ováricas/terapiaRESUMEN
TP53 aberrations constitute the highest risk subset of myelodysplastic neoplasms (MDS) and acute myeloid leukemia (AML). The International Consensus Classification questions the blast threshold between MDS and AML. In this study, we assess the distinction between MDS and AML for 76 patients with TP53 aberrations. We observed no significant differences between MDS and AML regarding TP53 genomics. Median overall survival (OS) was 223 days for the entire group, but prognostic discrimination within subgroups showed the most inferior OS (46 days) for AML with multihit allelic state plus TP53 variant allele frequency (VAF) > 50%. In multivariate analysis, unadjusted Cox models revealed the following variables as independent risk factors for mortality: AML (vs. MDS) (hazard ratio [HR]: 2.50, confidence interval [CI]: 1.4-4.4, p = 0.001), complex karyotype (HR: 3.00, CI: 1.4-6.1, p = 0.003), multihit status (HR: 2.30, CI 1.3-4.2, p = 0.005), and absence of hematopoietic cell transplant (HCT) (HR: 3.90, CI: 1.8-8.9, p = 0.0009). Clonal dynamic modeling showed a significant reduction in TP53 VAF with front-line hypomethylating agents. These findings clarify the impact of specific covariates on outcomes of TP53-aberrant myeloid neoplasms, irrespective of the diagnosis of MDS versus AML, and may influence HCT decisions.
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Immunotherapies that produce durable responses in some malignancies have failed in pancreatic ductal adenocarcinoma (PDAC) due to rampant immune suppression and poor tumor immunogenicity. We and others have demonstrated that induction of the senescence-associated secretory phenotype (SASP) can be an effective approach to activate anti-tumor natural killer (NK) cell and T cell immunity. In the present study, we found that the pancreas tumor microenvironment suppresses NK cell and T cell surveillance after therapy-induced senescence through enhancer of zeste homolog 2 (EZH2)-mediated epigenetic repression of proinflammatory SASP genes. EZH2 blockade stimulated production of SASP chemokines CCL2 and CXCL9/10, leading to enhanced NK cell and T cell infiltration and PDAC eradication in mouse models. EZH2 activity was also associated with suppression of chemokine signaling and cytotoxic lymphocytes and reduced survival in patients with PDAC. These results demonstrate that EZH2 represses the proinflammatory SASP and that EZH2 inhibition combined with senescence-inducing therapy could be a powerful means to achieve immune-mediated tumor control in PDAC.
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Carcinoma Ductal Pancreático , Neoplasias Pancreáticas , Animales , Ratones , Carcinoma Ductal Pancreático/tratamiento farmacológico , Carcinoma Ductal Pancreático/genética , Línea Celular Tumoral , Proteína Potenciadora del Homólogo Zeste 2/genética , Neoplasias Pancreáticas/tratamiento farmacológico , Neoplasias Pancreáticas/genética , Fenotipo Secretor Asociado a la Senescencia , Microambiente Tumoral/genéticaRESUMEN
BACKGROUND: Public health scientists have used spatial tools such as web-based Geographical Information System (GIS) applications to monitor and forecast the progression of the COVID-19 pandemic and track the impact of their interventions. The ability to track SARS-CoV-2 variants and incorporate the social determinants of health with street-level granularity can facilitate the identification of local outbreaks, highlight variant-specific geospatial epidemiology, and inform effective interventions. We developed a novel dashboard, the University of Massachusetts' Graphical user interface for Geographic Information (MAGGI) variant tracking system that combines GIS, health-associated sociodemographic data, and viral genomic data to visualize the spatiotemporal incidence of SARS-CoV-2 variants with street-level resolution while safeguarding protected health information. The specificity and richness of the dashboard enhance the local understanding of variant introductions and transmissions so that appropriate public health strategies can be devised and evaluated. OBJECTIVE: We developed a web-based dashboard that simultaneously visualizes the geographic distribution of SARS-CoV-2 variants in Central Massachusetts, the social determinants of health, and vaccination data to support public health efforts to locally mitigate the impact of the COVID-19 pandemic. METHODS: MAGGI uses a server-client model-based system, enabling users to access data and visualizations via an encrypted web browser, thus securing patient health information. We integrated data from electronic medical records, SARS-CoV-2 genomic analysis, and public health resources. We developed the following functionalities into MAGGI: spatial and temporal selection capability by zip codes of interest, the detection of variant clusters, and a tool to display variant distribution by the social determinants of health. MAGGI was built on the Environmental Systems Research Institute ecosystem and is readily adaptable to monitor other infectious diseases and their variants in real-time. RESULTS: We created a geo-referenced database and added sociodemographic and viral genomic data to the ArcGIS dashboard that interactively displays Central Massachusetts' spatiotemporal variants distribution. Genomic epidemiologists and public health officials use MAGGI to show the occurrence of SARS-CoV-2 genomic variants at high geographic resolution and refine the display by selecting a combination of data features such as variant subtype, subject zip codes, or date of COVID-19-positive sample collection. Furthermore, they use it to scale time and space to visualize association patterns between socioeconomics, social vulnerability based on the Centers for Disease Control and Prevention's social vulnerability index, and vaccination rates. We launched the system at the University of Massachusetts Chan Medical School to support internal research projects starting in March 2021. CONCLUSIONS: We developed a COVID-19 variant surveillance dashboard to advance our geospatial technologies to study SARS-CoV-2 variants transmission dynamics. This real-time, GIS-based tool exemplifies how spatial informatics can support public health officials, genomics epidemiologists, infectious disease specialists, and other researchers to track and study the spread patterns of SARS-CoV-2 variants in our communities.
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Sphingolipids play important signaling and structural roles in cells. Here, we find that during de novo sphingolipid biosynthesis, a toxic metabolite is formed with critical implications for cancer cell survival. The enzyme catalyzing the first step in this pathway, serine palmitoyltransferase complex (SPT), is upregulated in breast and other cancers. SPT is dispensable for cancer cell proliferation, as sphingolipids can be salvaged from the environment. However, SPT activity introduces a liability as its product, 3-ketodihydrosphingosine (3KDS), is toxic and requires clearance via the downstream enzyme 3-ketodihydrosphingosine reductase (KDSR). In cancer cells, but not normal cells, targeting KDSR induces toxic 3KDS accumulation leading to endoplasmic reticulum (ER) dysfunction and loss of proteostasis. Furthermore, the antitumor effect of KDSR disruption can be enhanced by increasing metabolic input (via high-fat diet) to allow greater 3KDS production. Thus, de novo sphingolipid biosynthesis entails a detoxification requirement in cancer cells that can be therapeutically exploited.
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Neoplasias , Serina C-Palmitoiltransferasa , Lipogénesis , Oxidorreductasas/metabolismo , Serina/metabolismo , Serina C-Palmitoiltransferasa/metabolismo , Esfingolípidos/metabolismo , Esfingosina/análogos & derivadosRESUMEN
Shigella spp. are highly adapted pathogens that cause bacillary dysentery in human and nonhuman primates. An unusual feature of Shigella pathogenesis is that this organism invades the colonic epithelia from the basolateral pole. Therefore, it has evolved the ability to disrupt the intestinal epithelial barrier to reach the basolateral surface. We have shown previously that the secreted serine protease A (SepA), which belongs to the family of serine protease autotransporters of Enterobacteriaceae, is responsible for the initial destabilization of the intestinal epithelial barrier that facilitates Shigella invasion. However, the mechanisms used by SepA to regulate this process remain unknown. To investigate the protein targets cleaved by SepA in the intestinal epithelium, we incubated a sample of homogenized human colon with purified SepA or with a catalytically inactive mutant of this protease. We discovered that SepA targets an array of 18 different proteins, including alpha-1 antitrypsin (AAT), a major circulating serine proteinase inhibitor in humans. In contrast to other serine proteases, SepA cleaved AAT without forming an inhibiting complex, which resulted in the generation of a neutrophil chemoattractant. We demonstrated that the products of the AAT-SepA reaction induce a mild but significant increase in neutrophil transepithelial migration in vitro. Moreover, the presence of AAT during Shigella infection stimulated neutrophil migration and dramatically enhanced the number of bacteria invading the intestinal epithelium in a SepA-dependent manner. We conclude that by cleaving AAT, SepA releases a chemoattractant that promotes neutrophil migration, which in turn disrupts the intestinal epithelial barrier to enable Shigella invasion. IMPORTANCEShigella is the second leading cause of diarrheal death globally. In this study, we identified the host protein targets of SepA, Shigella's major protein secreted in culture. We demonstrated that by cleaving AAT, a serine protease inhibitor important to protect surrounding tissue at inflammatory sites, SepA releases a neutrophil chemoattractant that enhances Shigella invasion. Moreover, SepA degraded AAT without becoming inhibited by the cleaved product, and SepA catalytic activity was enhanced at higher concentrations of AAT. Activation of SepA by an excess of AAT may be physiologically relevant at the early stages of Shigella infection, when the amount of synthesized SepA is very low compared to the concentration of AAT in the intestinal lumen. This observation may also help to explain the adeptness of Shigella infectivity at low dose, despite the requirement of reaching the basolateral side to invade and colonize the colonic epithelium.
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Proteínas Bacterianas/metabolismo , Factores Quimiotácticos/metabolismo , Disentería Bacilar/metabolismo , Células Epiteliales/microbiología , Neutrófilos/citología , Shigella/enzimología , alfa 1-Antitripsina/metabolismo , Proteínas Bacterianas/genética , Movimiento Celular , Factores Quimiotácticos/genética , Disentería Bacilar/microbiología , Disentería Bacilar/fisiopatología , Células Epiteliales/metabolismo , Humanos , Intestinos/citología , Intestinos/metabolismo , Intestinos/microbiología , Neutrófilos/metabolismo , Shigella/clasificación , Shigella/genética , alfa 1-Antitripsina/genéticaRESUMEN
TP53-aberrant myelodysplastic syndrome and acute myeloid leukemia have dismal outcomes. Here, we define the clinico-genomic landscape of TP53 disruptions in 40 patients and employ clonal dynamic modeling to map the mutational hierarchy against clinical outcomes. Most TP53 mutations (45.2%) localized to the L3 loop or LSH motif of the DNA-binding domain. TP53 disruptions had high co-occurrence with mutations in epigenetic regulators, spliceosome machinery, and cohesin complex and low co-occurrence with mutations in proliferative signaling genes. Ancestral and descendant TP53 mutations constituted measurable residual disease and fueled relapse. High mutant TP53 gene dosage predicted low durability of remission. The median overall survival (OS) was 280 days. Hypomethylating agent-based therapy served as an effective bridge to transplant, leading to improved median OS compared to patients who did not receive a transplant (14.7 vs. 5.1 months). OS was independent of the genomic location of TP53 disruption, which has implications for rational therapeutic design.
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Leucemia Mieloide Aguda , Síndromes Mielodisplásicos , Genes p53 , Perfil Genético , Humanos , Leucemia Mieloide Aguda/diagnóstico , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/terapia , Mutación , Síndromes Mielodisplásicos/diagnóstico , Síndromes Mielodisplásicos/genética , Síndromes Mielodisplásicos/terapia , Proteína p53 Supresora de Tumor/genéticaRESUMEN
Faced with the COVID-19 pandemic, the US system for developing and testing technologies was challenged in unparalleled ways. This article describes the multi-institutional, transdisciplinary team of the "RADxSM Tech Test Verification Core" and its role in expediting evaluations of COVID-19 testing devices. Expertise related to aspects of diagnostic testing was coordinated to evaluate testing devices with the goal of significantly expanding the ability to mass screen Americans to preserve lives and facilitate the safe return to work and school. Focal points included: laboratory and clinical device evaluation of the limit of viral detection, sensitivity, and specificity of devices in controlled and community settings; regulatory expertise to provide focused attention to barriers to device approval and distribution; usability testing from the perspective of patients and those using the tests to identify and overcome device limitations, and engineering assessment to evaluate robustness of design including human factors, manufacturability, and scalability.
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The micronutrient selenium is incorporated via the selenocysteine biosynthesis pathway into the rare amino acid selenocysteine, which is required in selenoproteins such as glutathione peroxidases and thioredoxin reductases1,2. Here, we show that selenophosphate synthetase 2 (SEPHS2), an enzyme in the selenocysteine biosynthesis pathway, is essential for survival of cancer, but not normal, cells. SEPHS2 is required in cancer cells to detoxify selenide, an intermediate that is formed during selenocysteine biosynthesis. Breast and other cancer cells are selenophilic, owing to a secondary function of the cystine/glutamate antiporter SLC7A11 that promotes selenium uptake and selenocysteine biosynthesis, which, by allowing production of selenoproteins such as GPX4, protects cells against ferroptosis. However, this activity also becomes a liability for cancer cells because selenide is poisonous and must be processed by SEPHS2. Accordingly, we find that SEPHS2 protein levels are elevated in samples from people with breast cancer, and that loss of SEPHS2 impairs growth of orthotopic mammary-tumour xenografts in mice. Collectively, our results identify a vulnerability of cancer cells and define the role of selenium metabolism in cancer.
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Inactivación Metabólica , Neoplasias/metabolismo , Selenio/metabolismo , Sistema de Transporte de Aminoácidos y+/metabolismo , Animales , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Línea Celular Tumoral , Supervivencia Celular , Femenino , Ferroptosis , Humanos , Ratones , Ratones Desnudos , Neoplasias/patología , Fosfolípido Hidroperóxido Glutatión Peroxidasa/metabolismo , Fosfotransferasas/metabolismo , Compuestos de Selenio/metabolismo , Selenocisteína/metabolismo , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
PURPOSE: The beta4 integrin has been implicated in functions associated with the genesis and progression of carcinomas based on data obtained from cell lines and mouse models. Data on its expression and relevance to human carcinomas, however, are relatively scant. The aim of this study was to assess its expression and prognostic significance in human breast carcinomas. EXPERIMENTAL DESIGN: We integrated data on beta4 expression from multiple gene profiling studies of breast tumors of known clinical outcome with immunohistochemical analysis of 105 breast carcinomas, and we identified genes whose expression correlates with that of beta4. RESULTS: The expression of both beta4 mRNA and protein is not homogeneous in breast cancer and it associates most significantly with the "basal-like" subtype of breast tumors (P = 0.008). No association between beta4 and HER2 expression was evident from either gene profiling or immunohistochemical analysis. To gain insight into the relevance of beta4 expression to human breast carcinomas, we generated a 65-gene "beta4 signature" based on integration of four published gene profiling studies that included the top 0.1% of genes that correlated with beta4, either positively or negatively. This beta4 signature predicted decreased time to tumor recurrence and survival of patients when applied to four data sets including two independent ones. CONCLUSIONS: These observations indicate that beta4 expression in human breast cancer is restricted and associated with basal-like cancers, and they support the hypothesis that beta4 may function in concert with a discrete set of proteins to facilitate the aggressive behavior of a subset of tumors.
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Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Perfilación de la Expresión Génica , Integrina beta4/biosíntesis , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias de la Mama/mortalidad , Análisis por Conglomerados , Femenino , Humanos , Inmunohistoquímica , Estimación de Kaplan-Meier , Queratina-5/biosíntesis , Queratina-6/biosíntesis , Persona de Mediana Edad , Pronóstico , ARN Mensajero/análisis , Receptor ErbB-2/biosíntesis , Receptores de Estrógenos/biosíntesis , Receptores de Progesterona/biosíntesisRESUMEN
INTRODUCTION: Basal-type, or triple-negative, breast cancer (lacking estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2 expression) is a high-risk disease for which no molecular therapies are currently available. We studied genetic signatures of basal breast cancer potentially suitable for therapeutic intervention. METHODS: We analyzed protein expression of the Notch-1 intracellular domain and survivin by immunohistochemistry in a series of basal breast cancer patients. A hierarchical clustering and overall survival analysis was carried out on a microarray mRNA database of 232 breast cancer patients. Fifteen published mRNA datasets containing estrogen receptor-negative or estrogen receptor-positive samples were subjected to meta-analysis for co-segregated gene expression. Experiments of plasmid transfection and gene silencing were carried out in estrogen receptor-negative MDA-MB-231 breast cancer cells. RESULTS: The developmental signaling regulator Notch-1 was highly expressed in breast cancer, compared with normal tissue, and was segregated with basal disease. Higher Notch-1 levels correlated with progressively abbreviated overall survival, and with increased expression of survivin, a tumor-associated cell death and mitotic regulator implicated in stem cell viability. Analysis of Pearson's correlation coefficient indicated that Notch-1 and survivin co-segregated in basal breast cancer. Notch-1 stimulation in MDA-MB-231 cells increased survivin expression, whereas silencing Notch reduced survivin levels. CONCLUSIONS: A Notch-1-survivin functional gene signature is a hallmark of basal breast cancer, and may contribute to disease pathogenesis. Antagonists of Notch and survivin currently in the clinic may be tested as novel molecular therapy for these recurrence-prone patients.
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Neoplasias de la Mama/genética , Perfilación de la Expresión Génica , Proteínas Asociadas a Microtúbulos/genética , Receptor Notch1/genética , Receptor alfa de Estrógeno/metabolismo , Femenino , Silenciador del Gen , Humanos , Técnicas para Inmunoenzimas , Proteínas Inhibidoras de la Apoptosis , Persona de Mediana Edad , Análisis de Secuencia por Matrices de Oligonucleótidos , Receptor Notch1/antagonistas & inhibidores , Receptores de Progesterona/metabolismo , Transducción de Señal , Survivin , TransfecciónRESUMEN
Retinoblastoma 1 (pRb) and the related pocket proteins, retinoblastoma-like 1 (p107) and retinoblastoma-like 2 (p130) (pRb(f), collectively), play a pivotal role in regulating eukaryotic cell cycle progression, apoptosis, and terminal differentiation. While aberrations in the pRb-signaling pathway are common in human cancers, the consequence of pRb(f) loss in the mammary gland has not been directly assayed in vivo. We reported previously that inactivating these critical cell cycle regulators in divergent cell types, either brain epithelium or astrocytes, abrogates the cell cycle restriction point, leading to increased cell proliferation and apoptosis, and predisposing to cancer. Here we report that mouse mammary epithelium is similar in its requirements for pRb(f) function; Rb(f) inactivation by T(121), a fragment of SV40 T antigen that binds to and inactivates pRb(f) proteins, increases proliferation and apoptosis. Mammary adenocarcinomas form within 16 mo. Most apoptosis is regulated by p53, which has no impact on proliferation, and heterozygosity for a p53 null allele significantly shortens tumor latency. Most tumors in p53 heterozygous mice undergo loss of the wild-type p53 allele. We show that the mechanism of p53 loss of heterozygosity is not simply the consequence of Chromosome 11 aneuploidy and further that chromosomal instability subsequent to p53 loss is minimal. The mechanisms for pRb and p53 tumor suppression in the epithelia of two distinct tissues, mammary gland and brain, are indistinguishable. Further, this study has produced a highly penetrant breast cancer model based on aberrations commonly observed in the human disease.
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Neoplasias de la Mama/genética , Mama/citología , Regulación Neoplásica de la Expresión Génica , Regulación de la Expresión Génica , Genes de Retinoblastoma , Neoplasias Encefálicas/genética , Mama/patología , Diferenciación Celular , División Celular , Progresión de la Enfermedad , Células Epiteliales/citología , Células Epiteliales/patología , Femenino , HumanosRESUMEN
[This corrects the article DOI: 10.1371/journal.pone.0181724.].