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1.
Cell Rep ; 43(4): 114041, 2024 Apr 23.
Article in English | MEDLINE | ID: mdl-38573857

ABSTRACT

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.


Subject(s)
Acyltransferases , CD24 Antigen , Ovarian Neoplasms , Phagocytosis , Animals , Female , Humans , Mice , Acyltransferases/metabolism , Amidohydrolases/metabolism , Amidohydrolases/genetics , CD24 Antigen/metabolism , Cell Line, Tumor , Glycosylphosphatidylinositols/metabolism , Macrophages/metabolism , Macrophages/immunology , Ovarian Neoplasms/immunology , Ovarian Neoplasms/metabolism , Ovarian Neoplasms/pathology , Ovarian Neoplasms/therapy
2.
EJHaem ; 4(4): 1059-1070, 2023 Nov.
Article in English | MEDLINE | ID: mdl-38024632

ABSTRACT

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.

3.
Nature ; 623(7987): 625-632, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37880368

ABSTRACT

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.


Subject(s)
Neoplasms , Uridine Diphosphate Glucuronic Acid , Humans , Neoplasms/drug therapy , Neoplasms/metabolism , Neoplasms/pathology , Signal Transduction , Uridine Diphosphate Glucuronic Acid/biosynthesis , Uridine Diphosphate Glucuronic Acid/metabolism , Uridine Diphosphate Xylose/biosynthesis , Uridine Diphosphate Xylose/metabolism , Adenocarcinoma of Lung , Lung Neoplasms
4.
Nat Cancer ; 4(6): 872-892, 2023 06.
Article in English | MEDLINE | ID: mdl-37142692

ABSTRACT

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.


Subject(s)
Carcinoma, Pancreatic Ductal , Pancreatic Neoplasms , Animals , Mice , Carcinoma, Pancreatic Ductal/drug therapy , Carcinoma, Pancreatic Ductal/genetics , Cell Line, Tumor , Enhancer of Zeste Homolog 2 Protein/genetics , Pancreatic Neoplasms/drug therapy , Pancreatic Neoplasms/genetics , Senescence-Associated Secretory Phenotype , Tumor Microenvironment/genetics
5.
Cell Rep ; 40(13): 111415, 2022 09 27.
Article in English | MEDLINE | ID: mdl-36170811

ABSTRACT

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.


Subject(s)
Neoplasms , Serine C-Palmitoyltransferase , Lipogenesis , Oxidoreductases/metabolism , Serine/metabolism , Serine C-Palmitoyltransferase/metabolism , Sphingolipids/metabolism , Sphingosine/analogs & derivatives
6.
JMIR Form Res ; 6(6): e37858, 2022 Jun 13.
Article in English | MEDLINE | ID: mdl-35658093

ABSTRACT

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.

7.
mBio ; 12(6): e0283321, 2021 12 21.
Article in English | MEDLINE | ID: mdl-34724811

ABSTRACT

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.


Subject(s)
Bacterial Proteins/metabolism , Chemotactic Factors/metabolism , Dysentery, Bacillary/metabolism , Epithelial Cells/microbiology , Neutrophils/cytology , Shigella/enzymology , alpha 1-Antitrypsin/metabolism , Bacterial Proteins/genetics , Cell Movement , Chemotactic Factors/genetics , Dysentery, Bacillary/microbiology , Dysentery, Bacillary/physiopathology , Epithelial Cells/metabolism , Humans , Intestines/cytology , Intestines/metabolism , Intestines/microbiology , Neutrophils/metabolism , Shigella/classification , Shigella/genetics , alpha 1-Antitrypsin/genetics
8.
Leuk Lymphoma ; 62(14): 3348-3360, 2021 12.
Article in English | MEDLINE | ID: mdl-34496723

ABSTRACT

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.


Subject(s)
Leukemia, Myeloid, Acute , Myelodysplastic Syndromes , Genes, p53 , Genetic Profile , Humans , Leukemia, Myeloid, Acute/diagnosis , Leukemia, Myeloid, Acute/genetics , Leukemia, Myeloid, Acute/therapy , Mutation , Myelodysplastic Syndromes/diagnosis , Myelodysplastic Syndromes/genetics , Myelodysplastic Syndromes/therapy , Tumor Suppressor Protein p53/genetics
9.
IEEE Open J Eng Med Biol ; 2: 142-151, 2021 Apr 28.
Article in English | MEDLINE | ID: mdl-34192286

ABSTRACT

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.

11.
Nat Metab ; 2(7): 603-611, 2020 07.
Article in English | MEDLINE | ID: mdl-32694795

ABSTRACT

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.


Subject(s)
Inactivation, Metabolic , Neoplasms/metabolism , Selenium/metabolism , Amino Acid Transport System y+/metabolism , Animals , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Cell Line, Tumor , Cell Survival , Female , Ferroptosis , Humans , Mice , Mice, Nude , Neoplasms/pathology , Phospholipid Hydroperoxide Glutathione Peroxidase/metabolism , Phosphotransferases/metabolism , Selenium Compounds/metabolism , Selenocysteine/metabolism , Xenograft Model Antitumor Assays
12.
Breast Cancer Res ; 21(1): 76, 2019 06 27.
Article in English | MEDLINE | ID: mdl-31248446

ABSTRACT

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.


Subject(s)
Gene Expression Regulation , Intercellular Signaling Peptides and Proteins/genetics , Mammary Glands, Human/metabolism , Mammary Glands, Human/pathology , Membrane Proteins/genetics , Transcriptome , Adult , Animals , Biomarkers , Biomarkers, Tumor , Breast Neoplasms/etiology , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Disease Models, Animal , Disease Progression , Female , Gene Expression Profiling , Gene Regulatory Networks , Humans , Hyperplasia , Mice , Mice, Knockout , Middle Aged , Signal Transduction
14.
PLoS One ; 12(7): e0181724, 2017.
Article in English | MEDLINE | ID: mdl-28738084

ABSTRACT

Members of the Dickkopf (Dkk) family of Wnt antagonists interrupt Wnt-induced receptor assembly and participate in axial patterning and cell fate determination. One family member, DKK3, does not block Wnt receptor activation. Loss of Dkk3 expression in cancer is associated with hyperproliferation and dysregulated ß-catenin signaling, and ectopic expression of Dkk3 halts cancer growth. The molecular events mediating the DKK3-dependent arrest of ß-catenin-driven cell proliferation in cancer cells are unknown. Here we report the identification of a new intracellular gene product originating from the Dkk3 locus. This Dkk3b transcript originates from a second transcriptional start site located in intron 2 of the Dkk3 gene. It is essential for early mouse development and is a newly recognized regulator of ß-catenin signaling and cell proliferation. Dkk3b interrupts nuclear translocation ß-catenin by capturing cytoplasmic, unphosphorylated ß-catenin in an extra-nuclear complex with ß-TrCP. These data reveal a new regulator of one of the most studied signal transduction pathways in metazoans and provides a novel, completely untapped therapeutic target for silencing the aberrant ß-catenin signaling that drives hyperproliferation in many cancers.


Subject(s)
Cell Proliferation/genetics , Cell Proliferation/physiology , Intercellular Signaling Peptides and Proteins/genetics , Intercellular Signaling Peptides and Proteins/metabolism , Signal Transduction/genetics , Signal Transduction/physiology , Animals , Cytoplasm/genetics , Cytoplasm/metabolism , Cytoplasm/physiology , Female , Mice, Inbred C57BL , Neoplasms/genetics , Neoplasms/metabolism , Pregnancy , Rats , Rats, Sprague-Dawley , Wnt Proteins/genetics , Wnt Proteins/metabolism , beta Catenin/genetics , beta Catenin/metabolism , beta-Transducin Repeat-Containing Proteins/genetics , beta-Transducin Repeat-Containing Proteins/metabolism
15.
Cancer Res ; 75(7): 1482-94, 2015 Apr 01.
Article in English | MEDLINE | ID: mdl-25670168

ABSTRACT

Radiotherapy is a curative treatment option in prostate cancer. Nevertheless, patients with high-risk prostate cancer are prone to relapse. Identification of the predictive biomarkers and molecular mechanisms of radioresistance bears promise to improve cancer therapies. In this study, we show that aldehyde dehydrogenase (ALDH) activity is indicative of radioresistant prostate progenitor cells with an enhanced DNA repair capacity and activation of epithelial-mesenchymal transition (EMT). Gene expression profiling of prostate cancer cells, their radioresistant derivatives, ALDH(+) and ALDH(-) cell populations revealed the mechanisms, which link tumor progenitors to radioresistance, including activation of the WNT/ß-catenin signaling pathway. We found that expression of the ALDH1A1 gene is regulated by the WNT signaling pathway and co-occurs with expression of ß-catenin in prostate tumor specimens. Inhibition of the WNT pathway led to a decrease in ALDH(+) tumor progenitor population and to radiosensitization of cancer cells. Taken together, our results indicate that ALDH(+) cells contribute to tumor radioresistance and their molecular targeting may enhance the effectiveness of radiotherapy.


Subject(s)
Aldehyde Dehydrogenase/metabolism , Neoplastic Stem Cells/enzymology , Prostatic Neoplasms/enzymology , beta Catenin/physiology , Aldehyde Dehydrogenase/genetics , Aldehyde Dehydrogenase 1 Family , Animals , Cell Line, Tumor , Gene Expression Regulation, Neoplastic , Humans , Male , Mice, Nude , Neoplasm Transplantation , Neoplastic Stem Cells/radiation effects , Prostatic Neoplasms/pathology , Radiation Tolerance , Retinal Dehydrogenase , Transcriptome , Wnt Signaling Pathway
16.
Cancer Genomics Proteomics ; 11(3): 115-26, 2014.
Article in English | MEDLINE | ID: mdl-24969692

ABSTRACT

BACKGROUND: We previously developed a mouse model of breast cancer that mimics human triple-negative breast cancer (TNBC) by inactivating the Retinoblastoma (Rb), Transformation related protein 53 (p53), and Breast cancer 1 (Brca1) pathways in the mammary gland. Despite inactivation of all three tumor suppressors throughout the epithelium, low tumor multiplicity indicated that malignant carcinoma progression requires additional oncogenic stimuli. MATERIALS AND METHODS: In order to identify collaborating genetic events, we performed integrated analysis of 18 tumors (eight tumors with inactivation of pRbf/Brca1/p53 and ten tumors with inactivation of pRbf/p53) using comparative genomic hybridization and global gene expression. We then conducted flow cytometric analysis, immunostaining, tumorsphere, and cell viability assays. RESULTS: Copy number aberrations were correlated with the transcript levels of 7.55% of genes spanned by the altered genomic regions. Recurrent genomic losses spanning large regions of chromosomes 4 and 10 included several cell death genes. Among the amplified genes were well-known drivers of tumorigenesis including Wingless-related MMTV integration site 2 (Wnt2), as well as potentially novel driver mutations including the Late cornified envelope (LCE) gene family. These tumors have a stem/luminal progenitor phenotype and active ß-catenin signaling. Tumorsphere formation and cell survival are suppressed by Wnt pathway inhibitors. CONCLUSION: Our novel mouse model mimics human TNBC and provides a platform to triage the pathways that underlie malignant tumor progression.


Subject(s)
Cell Transformation, Neoplastic/genetics , Triple Negative Breast Neoplasms/genetics , Animals , Cell Survival/genetics , Cell Transformation, Neoplastic/metabolism , Cluster Analysis , Comparative Genomic Hybridization , Computational Biology , DNA Copy Number Variations , Disease Models, Animal , Female , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Mice , Mice, Transgenic , Neoplastic Stem Cells/metabolism , Phenotype , Signal Transduction , Triple Negative Breast Neoplasms/metabolism , Wnt Signaling Pathway
17.
EMBO Mol Med ; 5(4): 488-508, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23436775

ABSTRACT

The characterization of cells with tumour initiating potential is significant for advancing our understanding of cancer and improving therapy. Aggressive, triple-negative breast cancers (TNBCs) are enriched for tumour-initiating cells (TICs). We investigated that hypothesis that VEGF receptors expressed on TNBC cells mediate autocrine signalling that contributes to tumour initiation. We discovered the VEGF receptor neuropilin-2 (NRP2) is expressed preferentially on TICs, involved in the genesis of TNBCs and necessary for tumour initiation. The mechanism by which NRP2 signalling promotes tumour initiation involves stimulation of the α6ß1 integrin, focal adhesion kinase-mediated activation of Ras/MEK signalling and consequent expression of the Hedgehog effector GLI1. GLI1 also induces BMI-1, a key stem cell factor, and it enhances NRP2 expression and the function of α6ß1, establishing an autocrine loop. NRP2 can be targeted in vivo to retard tumour initiation. These findings reveal a novel autocrine pathway involving VEGF/NRP2, α6ß1 and GLI1 that contributes to the initiation of TNBC. They also support the feasibility of NRP2-based therapy for the treatment of TNBC that targets and impedes the function of TICs.


Subject(s)
Autocrine Communication , Breast Neoplasms/metabolism , Integrin alpha6beta1/metabolism , Neuropilin-2/metabolism , Transcription Factors/metabolism , Animals , Breast Neoplasms/genetics , Breast Neoplasms/physiopathology , Female , Gene Expression Regulation, Neoplastic , Humans , Integrin alpha6beta1/genetics , Mice , Mice, Inbred NOD , Mice, Transgenic , Mitogen-Activated Protein Kinase 7/genetics , Mitogen-Activated Protein Kinase 7/metabolism , Neoplastic Stem Cells/metabolism , Neuropilin-2/genetics , Transcription Factors/genetics , Zinc Finger Protein GLI1
18.
PLoS Genet ; 8(11): e1003027, 2012.
Article in English | MEDLINE | ID: mdl-23173005

ABSTRACT

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.


Subject(s)
BRCA1 Protein , Breast Neoplasms , Retinoblastoma Protein , Tumor Suppressor Protein p53 , Animals , Apoptosis , BRCA1 Protein/genetics , BRCA1 Protein/metabolism , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism , Breast Neoplasms/genetics , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Estrogen Receptor alpha/genetics , Estrogen Receptor alpha/metabolism , Evolution, Molecular , Female , Gene Expression Regulation, Neoplastic , Humans , Mammary Glands, Animal/metabolism , Mammary Glands, Animal/pathology , Metabolic Networks and Pathways , Mice , Receptor, ErbB-2/genetics , Receptor, ErbB-2/metabolism , Receptors, Progesterone/genetics , Receptors, Progesterone/metabolism , Retinoblastoma Protein/genetics , Retinoblastoma Protein/metabolism , Tumor Suppressor Protein p53/genetics , Tumor Suppressor Protein p53/metabolism
19.
PLoS One ; 7(9): e45684, 2012.
Article in English | MEDLINE | ID: mdl-23049838

ABSTRACT

Breast cancers with a basal-like gene signature are primarily triple-negative, frequently metastatic, and carry a poor prognosis. Basal-like breast cancers are enriched for markers of breast cancer stem cells as well as markers of epithelial-mesenchymal transition (EMT). While EMT is generally thought to be important in the process of metastasis, in vivo evidence of EMT in human disease remains rare. Here we report a novel model of human triple-negative breast cancer, the DKAT cell line, which was isolated from an aggressive, treatment-resistant triple-negative breast cancer that demonstrated morphological and biochemical evidence suggestive of phenotypic plasticity in the patient. The DKAT cell line displays a basal-like phenotype in vitro when cultured in serum-free media, and undergoes phenotypic changes consistent with EMT/MET in response to serum-containing media, a unique property among the breast cancer cell lines we tested. This EMT is marked by increased expression of the transcription factor Zeb1, and Zeb1 is required for the enhanced migratory ability of DKAT cells in the mesenchymal state. DKAT cells also express progenitor-cell markers, and single DKAT cells are able to generate tumorspheres containing both epithelial and mesenchymal cell types. In vivo, as few as ten DKAT cells are capable of forming xenograft tumors which display a range of epithelial and mesenchymal phenotypes. The DKAT model provides a novel model to study the molecular mechanisms regulating phenotypic plasticity and the aggressive biology of triple-negative breast cancers.


Subject(s)
Breast Neoplasms/pathology , Adult , Animals , Bone Marrow/pathology , Breast Neoplasms/metabolism , Cell Line, Tumor , Culture Media, Serum-Free/pharmacology , Cytogenetics , Epithelial-Mesenchymal Transition , Exons , Female , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Humans , Karyotyping , Mice , Neoplasm Metastasis , Neoplasm Transplantation , Phenotype , Prognosis
20.
Proc Natl Acad Sci U S A ; 109(17): E1038-47, 2012 Apr 24.
Article in English | MEDLINE | ID: mdl-22493246

ABSTRACT

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.


Subject(s)
Carcinoma, Pancreatic Ductal/genetics , Genes, ras , Pancreatic Neoplasms/genetics , Transcription Factors/metabolism , Animals , Carcinoma, Pancreatic Ductal/pathology , Cell Proliferation , I-kappa B Proteins/metabolism , Mice , NF-kappa B/metabolism , Pancreatic Neoplasms/pathology , Proto-Oncogene Proteins/metabolism
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