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1.
J Biol Chem ; 299(7): 104834, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-37201585

RESUMEN

Chromatin organization is highly dynamic and modulates DNA replication, transcription, and chromosome segregation. Condensin is essential for chromosome assembly during mitosis and meiosis, as well as maintenance of chromosome structure during interphase. While it is well established that sustained condensin expression is necessary to ensure chromosome stability, the mechanisms that control its expression are not yet known. Herein, we report that disruption of cyclin-dependent kinase 7 (CDK7), the core catalytic subunit of CDK-activating kinase, leads to reduced transcription of several condensin subunits, including structural maintenance of chromosomes 2 (SMC2). Live and static microscopy revealed that inhibiting CDK7 signaling prolongs mitosis and induces chromatin bridge formation, DNA double-strand breaks, and abnormal nuclear features, all of which are indicative of mitotic catastrophe and chromosome instability. Affirming the importance of condensin regulation by CDK7, genetic suppression of the expression of SMC2, a core subunit of this complex, phenocopies CDK7 inhibition. Moreover, analysis of genome-wide chromatin conformation using Hi-C revealed that sustained activity of CDK7 is necessary to maintain chromatin sublooping, a function that is ascribed to condensin. Notably, the regulation of condensin subunit gene expression is independent of superenhancers. Together, these studies reveal a new role for CDK7 in sustaining chromatin configuration by ensuring the expression of condensin genes, including SMC2.


Asunto(s)
Cromatina , Quinasas Ciclina-Dependientes , Transducción de Señal , Cromatina/genética , Cromatina/metabolismo , Quinasas Ciclina-Dependientes/genética , Quinasas Ciclina-Dependientes/metabolismo , Mitosis/genética , Inestabilidad Cromosómica/genética , Humanos , Línea Celular Tumoral , Regulación de la Expresión Génica/genética , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Silenciador del Gen
2.
J Biol Chem ; 297(4): 101162, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34481843

RESUMEN

Cyclin-dependent kinase 7 (CDK7) is a master regulatory kinase that drives cell cycle progression and stimulates expression of oncogenes in a myriad of cancers. Inhibitors of CDK7 (CDK7i) are currently in clinical trials; however, as with many cancer therapies, patients will most likely experience recurrent disease due to acquired resistance. Identifying targets underlying CDK7i resistance will facilitate prospective development of new therapies that can circumvent such resistance. Here we utilized triple-negative breast cancer as a model to discern mechanisms of resistance as it has been previously shown to be highly responsive to CDK7 inhibitors. After generating cell lines with acquired resistance, high-throughput RNA sequencing revealed significant upregulation of genes associated with efflux pumps and transforming growth factor-beta (TGF-ß) signaling pathways. Genetic silencing or pharmacological inhibition of ABCG2, an efflux pump associated with multidrug resistance, resensitized resistant cells to CDK7i, indicating a reliance on these transporters. Expression of activin A (INHBA), a member of the TGF-ß family of ligands, was also induced, whereas its intrinsic inhibitor, follistatin (FST), was repressed. In resistant cells, increased phosphorylation of SMAD3, a downstream mediator, confirmed an increase in activin signaling, and phosphorylated SMAD3 directly bound the ABCG2 promoter regulatory region. Finally, pharmacological inhibition of TGF-ß/activin receptors or genetic silencing of SMAD4, a transcriptional partner of SMAD3, reversed the upregulation of ABCG2 in resistant cells and phenocopied ABCG2 inhibition. This study reveals that inhibiting the TGF-ß/Activin-ABCG2 pathway is a potential avenue for preventing or overcoming resistance to CDK7 inhibitors.


Asunto(s)
Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2/biosíntesis , Quinasas Ciclina-Dependientes/antagonistas & inhibidores , Resistencia a Antineoplásicos/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Subunidades beta de Inhibinas/metabolismo , Proteínas de Neoplasias/biosíntesis , Inhibidores de Proteínas Quinasas/farmacología , Transducción de Señal/efectos de los fármacos , Factor de Crecimiento Transformador beta/metabolismo , Neoplasias de la Mama Triple Negativas/metabolismo , Regulación hacia Arriba/efectos de los fármacos , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2/genética , Línea Celular Tumoral , Quinasas Ciclina-Dependientes/genética , Quinasas Ciclina-Dependientes/metabolismo , Resistencia a Antineoplásicos/genética , Femenino , Humanos , Subunidades beta de Inhibinas/genética , Proteínas de Neoplasias/genética , Transducción de Señal/genética , Factor de Crecimiento Transformador beta/genética , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Neoplasias de la Mama Triple Negativas/genética , Neoplasias de la Mama Triple Negativas/patología , Quinasa Activadora de Quinasas Ciclina-Dependientes
3.
J Biol Chem ; 295(33): 11707-11719, 2020 08 14.
Artículo en Inglés | MEDLINE | ID: mdl-32576660

RESUMEN

The phenotypes of each breast cancer subtype are defined by their transcriptomes. However, the transcription factors that regulate differential patterns of gene expression that contribute to specific disease outcomes are not well understood. Here, using gene silencing and overexpression approaches, RNA-Seq, and splicing analysis, we report that the transcription factor B-cell leukemia/lymphoma 11A (BCL11A) is highly expressed in triple-negative breast cancer (TNBC) and drives metastatic disease. Moreover, BCL11A promotes cancer cell invasion by suppressing the expression of muscleblind-like splicing regulator 1 (MBNL1), a splicing regulator that suppresses metastasis. This ultimately increases the levels of an alternatively spliced isoform of integrin-α6 (ITGA6), which is associated with worse patient outcomes. These results suggest that BCL11A sustains TNBC cell invasion and metastatic growth by repressing MBNL1-directed splicing of ITGA6 Our findings also indicate that BCL11A lies at the interface of transcription and splicing and promotes aggressive TNBC phenotypes.


Asunto(s)
Regulación Neoplásica de la Expresión Génica , Invasividad Neoplásica/genética , Proteínas Represoras/genética , Neoplasias de la Mama Triple Negativas/genética , Regulación hacia Arriba , Línea Celular Tumoral , Progresión de la Enfermedad , Femenino , Humanos , Invasividad Neoplásica/patología , Metástasis de la Neoplasia/genética , Metástasis de la Neoplasia/patología , Neoplasias de la Mama Triple Negativas/patología
4.
Breast Cancer Res ; 22(1): 66, 2020 06 18.
Artículo en Inglés | MEDLINE | ID: mdl-32552913

RESUMEN

BACKGROUND: Triple-negative breast cancer (TNBC) is characterized by high rates of recurrence and poor overall survival. This is due, in part, to a deficiency of targeted therapies, making it essential to identify therapeutically targetable driver pathways of this disease. While epidermal growth factor receptor (EGFR) is expressed in 60% of TNBCs and drives disease progression, attempts to inhibit EGFR in unselected TNBC patients have had a marginal impact on outcomes. Hence, we sought to identify the mechanisms that dictate EGFR expression and inhibitor response to provide a path for improving the utility of these drugs. In this regard, the majority of TNBCs express low levels of the transcription factor, Krüppel-like factor 4 (KLF4), while a small subset is associated with high expression. KLF4 and EGFR have also been reported to have opposing actions in TNBC. Thus, we tested whether KLF4 controls the expression of EGFR and cellular response to its pharmacological inhibition. METHODS: KLF4 was transiently overexpressed in MDA-MB-231 and MDA-MB-468 cells or silenced in MCF10A cells. Migration and invasion were assessed using modified Boyden chamber assays, and proliferation was measured by EdU incorporation. Candidate downstream targets of KLF4, including EGFR, were identified using reverse phase protein arrays of MDA-MB-231 cells following enforced KLF4 expression. The ability of KLF4 to suppress EGFR gene and protein expression and downstream signaling was assessed by RT-PCR and western blot, respectively. ChIP-PCR confirmed KLF4 binding to the EGFR promoter. Response to erlotinib in the context of KLF4 overexpression or silencing was assessed using cell number and dose-response curves. RESULTS: We report that KLF4 is a major determinant of EGFR expression and activity in TNBC cells. KLF4 represses transcription of the EGFR gene, leading to reduced levels of total EGFR, its activated/phosphorylated form (pEGFR), and its downstream signaling intermediates. Moreover, KLF4 suppression of EGFR is a necessary intermediary step for KLF4 to inhibit aggressive TNBC phenotypes. Most importantly, KLF4 dictates the sensitivity of TNBC cells to erlotinib, an FDA-approved inhibitor of EGFR. CONCLUSIONS: KLF4 is a major regulator of the efficacy of EGFR inhibitors in TNBC cells that may underlie the variable effectiveness of such drugs in patients.


Asunto(s)
Antineoplásicos/farmacología , Clorhidrato de Erlotinib/farmacología , Factores de Transcripción de Tipo Kruppel/metabolismo , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Neoplasias de la Mama Triple Negativas/genética , Apoptosis/efectos de los fármacos , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Movimiento Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Receptores ErbB/antagonistas & inhibidores , Receptores ErbB/genética , Receptores ErbB/metabolismo , Femenino , Humanos , Factor 4 Similar a Kruppel , Factores de Transcripción de Tipo Kruppel/genética , Fosforilación , Transducción de Señal , Neoplasias de la Mama Triple Negativas/metabolismo , Neoplasias de la Mama Triple Negativas/patología
5.
J Biol Chem ; 291(45): 23756-23768, 2016 Nov 04.
Artículo en Inglés | MEDLINE | ID: mdl-27650498

RESUMEN

Bromodomain and extraterminal (BET) proteins are epigenetic "readers" that recognize acetylated histones and mark areas of the genome for transcription. BRD4, a BET family member protein, has been implicated in a number of types of cancer, and BET protein inhibitors (BETi) are efficacious in many preclinical cancer models. However, the drivers of response to BETi vary depending on tumor type, and little is known regarding the target genes conveying BETi activity in triple-negative breast cancer (TNBC). Here, we show that BETi repress growth of multiple in vitro and in vivo models of TNBC by inducing two terminal responses: apoptosis and senescence. Unlike in other cancers, response to BETi in TNBC is not dependent upon suppression of MYC Instead, both end points are preceded by the appearance of polyploid cells caused by the suppression of Aurora kinases A and B (AURKA/B), which are critical mediators of mitosis. In addition, AURKA/B inhibitors phenocopy the effects of BETi. These results indicate that Aurora kinases play an important role in the growth suppressive activity of BETi in TNBC. Elucidating the mechanism of response to BETi in TNBC should 1) facilitate the prediction of how distinct TNBC tumors will respond to BETi and 2) inform the rational design of drug combination therapies.


Asunto(s)
Antineoplásicos/uso terapéutico , Aurora Quinasa A/antagonistas & inhibidores , Aurora Quinasa B/antagonistas & inhibidores , Mama/efectos de los fármacos , Proteínas Nucleares/antagonistas & inhibidores , Inhibidores de Proteínas Quinasas/uso terapéutico , Factores de Transcripción/antagonistas & inhibidores , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Animales , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Aurora Quinasa A/metabolismo , Aurora Quinasa B/metabolismo , Mama/metabolismo , Mama/patología , Proteínas de Ciclo Celular , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Femenino , Humanos , Ratones , Ratones Endogámicos NOD , Ratones SCID , Proteínas Nucleares/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Factores de Transcripción/metabolismo , Neoplasias de la Mama Triple Negativas/metabolismo , Neoplasias de la Mama Triple Negativas/patología
6.
Breast Cancer Res ; 19(1): 66, 2017 06 05.
Artículo en Inglés | MEDLINE | ID: mdl-28583174

RESUMEN

BACKGROUND: Follistatin (FST) is an intrinsic inhibitor of activin, a member of the transforming growth factor-ß superfamily of ligands. The prognostic value of FST and its family members, the follistatin-like (FSTL) proteins, have been studied in various cancers. However, these studies, as well as limited functional analyses of the FSTL proteins, have yielded conflicting results on the role of these proteins in disease progression. Furthermore, very few have been focused on FST itself. We assessed whether FST may be a suppressor of tumorigenesis and/or metastatic progression in breast cancer. METHODS: Using publicly available gene expression data, we examined the expression patterns of FST and INHBA, a subunit of activin, in normal and cancerous breast tissue and the prognostic value of FST in breast cancer metastases, recurrence-free survival, and overall survival. The functional effects of activin and FST on in vitro proliferation, migration, and invasion of breast cancer cells were also examined. FST overexpression in an autochthonous mouse model of breast cancer was then used to assess the in vivo impact of FST on metastatic progression. RESULTS: Examination of multiple breast cancer datasets revealed that FST expression is reduced in breast cancers compared with normal tissue and that low FST expression predicts increased metastasis and reduced overall survival. FST expression was also reduced in a mouse model of HER2/Neu-induced metastatic breast cancer. We found that FST blocks activin-induced breast epithelial cell migration in vitro, suggesting that its loss may promote breast cancer aggressiveness. To directly determine if FST restoration could inhibit metastatic progression, we transgenically expressed FST in the HER2/Neu model. Although FST had no impact on tumor initiation or growth, it completely blocked the formation of lung metastases. CONCLUSIONS: These data indicate that FST is a bona fide metastasis suppressor in this mouse model and support future efforts to develop an FST mimetic to suppress metastatic progression.


Asunto(s)
Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Folistatina/genética , Receptor ErbB-2/genética , Proteínas Supresoras de Tumor/genética , Animales , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/mortalidad , Línea Celular Tumoral , Movimiento Celular/genética , Proliferación Celular , Supervivencia Celular/genética , Bases de Datos Genéticas , Femenino , Folistatina/metabolismo , Humanos , Estimación de Kaplan-Meier , Ratones , Ratones Transgénicos , Metástasis de la Neoplasia , Estadificación de Neoplasias , Pronóstico , Receptor ErbB-2/metabolismo , Proteínas Supresoras de Tumor/metabolismo
7.
Proc Natl Acad Sci U S A ; 111(49): 17456-61, 2014 Dec 09.
Artículo en Inglés | MEDLINE | ID: mdl-25422456

RESUMEN

DNA double-strand break (DSB) repair is not only key to genome stability but is also an important anticancer target. Through an shRNA library-based screening, we identified ubiquitin-conjugating enzyme H7 (UbcH7, also known as Ube2L3), a ubiquitin E2 enzyme, as a critical player in DSB repair. UbcH7 regulates both the steady-state and replicative stress-induced ubiquitination and proteasome-dependent degradation of the tumor suppressor p53-binding protein 1 (53BP1). Phosphorylation of 53BP1 at the N terminus is involved in the replicative stress-induced 53BP1 degradation. Depletion of UbcH7 stabilizes 53BP1, leading to inhibition of DSB end resection. Therefore, UbcH7-depleted cells display increased nonhomologous end-joining and reduced homologous recombination for DSB repair. Accordingly, UbcH7-depleted cells are sensitive to DNA damage likely because they mainly used the error-prone nonhomologous end-joining pathway to repair DSBs. Our studies reveal a novel layer of regulation of the DSB repair choice and propose an innovative approach to enhance the effect of radiotherapy or chemotherapy through stabilizing 53BP1.


Asunto(s)
Roturas del ADN de Doble Cadena , Reparación del ADN , Regulación Neoplásica de la Expresión Génica , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Enzimas Ubiquitina-Conjugadoras/metabolismo , Camptotecina/química , Línea Celular Tumoral , Supervivencia Celular , Daño del ADN , Células HEK293 , Humanos , Fosforilación , Pronóstico , Complejo de la Endopetidasa Proteasomal/química , ARN Interferente Pequeño/metabolismo , Proteína 1 de Unión al Supresor Tumoral P53 , Ubiquitina/química
9.
J Biol Chem ; 289(35): 24102-13, 2014 Aug 29.
Artículo en Inglés | MEDLINE | ID: mdl-25012653

RESUMEN

Breast cancer is a heterogeneous disease comprised of distinct subtypes predictive of patient outcome. Tumors of the basal-like subtype have a poor prognosis due to inherent aggressiveness and the lack of targeted therapeutics. Basal-like tumors typically lack estrogen receptor-α, progesterone receptor and HER2/ERBB2, or in other words they are triple negative (TN). Continued evaluation of basal-like breast cancer (BLBC) biology is essential to identify novel therapeutic targets. Expression of the pi subunit of the GABA(A) receptor (GABRP) is associated with the BLBC/TN subtype, and herein, we reveal its expression also correlates with metastases to the brain and poorer patient outcome. GABRP expression in breast cancer cell lines also demonstrates a significant correlation with the basal-like subtype suggesting that GABRP functions in the initiation and/or progression of basal-like tumors. To address this postulate, we stably silenced GABRP in two BLBC cell lines, HCC1187 and HCC70 cells. Decreased GABRP reduces in vitro tumorigenic potential and migration concurrent with alterations in the cytoskeleton, specifically diminished cellular protrusions and expression of the BLBC-associated cytokeratins, KRT5, KRT6B, KRT14, and KRT17. Silencing GABRP also decreases phosphorylation of extracellular regulated kinase 1/2 (ERK1/2) in both cell lines and selective inhibition of ERK1/2 similarly decreases the basal-like cytokeratins as well as migration. Combined, these data reveal a GABRP-ERK1/2-cytokeratin axis that maintains the migratory phenotype of basal-like breast cancer. GABRP is a component of a cell surface receptor, thus, these findings suggest that targeting this new signaling axis may have therapeutic potential in BLBC.


Asunto(s)
Neoplasias de la Mama/patología , Sistema de Señalización de MAP Quinasas , Receptores de GABA-A/fisiología , Neoplasias de la Mama/enzimología , Línea Celular , Activación Enzimática , Perfilación de la Expresión Génica , Silenciador del Gen , Humanos , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptores de GABA-A/genética , Análisis de Supervivencia
10.
Cell Death Differ ; 31(6): 768-778, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38627584

RESUMEN

The alternative splicing of PML precursor mRNA gives rise to various PML isoforms, yet their expression profile in breast cancer cells remains uncharted. We discovered that PML1 is the most abundant isoform in all breast cancer subtypes, and its expression is associated with unfavorable prognosis in estrogen receptor-positive (ER+) breast cancers. PML depletion reduces cell proliferation, invasion, and stemness, while heterologous PML1 expression augments these processes and fuels tumor growth and resistance to fulvestrant, an FDA-approved drug for ER+ breast cancer, in a mouse model. Moreover, PML1, rather than the well-known tumor suppressor isoform PML4, rescues the proliferation of PML knockdown cells. ChIP-seq analysis reveals significant overlap between PML-, ER-, and Myc-bound promoters, suggesting their coordinated regulation of target gene expression, including genes involved in breast cancer stem cells (BCSCs), such as JAG1, KLF4, YAP1, SNAI1, and MYC. Loss of PML reduces BCSC-related gene expression, and exogenous PML1 expression elevates their expression. Consistently, PML1 restores the association of PML with these promoters in PML-depleted cells. We identified a novel association between PML1 and WDR5, a key component of H3K4 methyltransferase (HMTs) complexes that catalyze H3K4me1 and H3K4me3. ChIP-seq analyses showed that the loss of PML1 reduces H3K4me3 in numerous loci, including BCSC-associated gene promoters. Additionally, PML1, not PML4, re-establishes the H3K4me3 mark on these promoters in PML-depleted cells. Significantly, PML1 is essential for recruiting WDR5, MLL1, and MLL2 to these gene promoters. Inactivating WDR5 by knockdown or inhibitors phenocopies the effects of PML1 loss, reducing BCSC-related gene expression and tumorsphere formation and enhancing fulvestrant's anticancer activity. Our findings challenge the conventional understanding of PML as a tumor suppressor, redefine its role as a promoter of tumor growth in breast cancer, and offer new insights into the unique roles of PML isoforms in breast cancer.


Asunto(s)
Neoplasias de la Mama , Histonas , Factor 4 Similar a Kruppel , Células Madre Neoplásicas , Proteína de la Leucemia Promielocítica , Receptores de Estrógenos , Humanos , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Neoplasias de la Mama/genética , Femenino , Proteína de la Leucemia Promielocítica/metabolismo , Proteína de la Leucemia Promielocítica/genética , Animales , Receptores de Estrógenos/metabolismo , Receptores de Estrógenos/genética , Ratones , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patología , Histonas/metabolismo , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Péptidos y Proteínas de Señalización Intracelular/genética , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica
11.
Biol Reprod ; 89(1): 10, 2013 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-23677979

RESUMEN

Expression of FOXC1, a forkhead box transcription factor, correlates with the human basal-like breast cancer (BLBC) subtype, and functional analyses have revealed its importance for in vitro invasiveness of BLBC cells. Women diagnosed with this breast tumor subtype have a poorer outcome because of the lack of targeted therapies; thus, continued investigation of factors driving these tumors is critical to uncover novel therapeutic targets. Several processes that dictate normal mammary morphogenesis parallel cancer progression, and enforced expression of FOXC1 can induce a progenitor state in more-differentiated mammary epithelial cells. Consequently, evaluating how FOXC1 functions in the normal gland is critical to further understand BLBC biology. Although FOXC1 is well known to control normal development of a number of tissues, its role in the mammary gland has not yet been investigated. Herein, we describe FOXC1 expression patterning in the normal breast, where it is localized to the basal/myoepithelium, suggesting that FOXC1 would be required for normal development. However, mammary glands lacking Foxc1 have no overt defect in ductal outgrowth, alveologenesis, or lineage specification. Of significant interest, we found that expression of FOXC1 is enriched in the normal luminal progenitor population, which is the postulated cell of origin of BLBC. These results indicate that FOXC1 is unnecessary for mammary morphogenesis and that its role in BLBC likely involves processes that are unrelated to cell lineage specification.


Asunto(s)
Células Epiteliales/fisiología , Factores de Transcripción Forkhead/metabolismo , Glándulas Mamarias Animales/citología , Glándulas Mamarias Animales/metabolismo , Células Madre Adultas/citología , Células Madre Adultas/fisiología , Animales , Células Epiteliales/citología , Femenino , Factores de Transcripción Forkhead/fisiología , Masculino , Glándulas Mamarias Animales/crecimiento & desarrollo , Ratones , Ratones Endogámicos C57BL , Morfogénesis
12.
Endocrinology ; 164(8)2023 06 26.
Artículo en Inglés | MEDLINE | ID: mdl-37394919

RESUMEN

The advent of sequencing technologies for assessing chromosome conformations has provided a wealth of information on the organization of the 3-dimensional genome and its role in cancer progression. It is now known that changes in chromatin folding and accessibility can promote aberrant activation or repression of transcriptional programs that can drive tumorigenesis and progression in diverse cancers. This includes breast cancer, which comprises several distinct subtypes defined by their unique transcriptomes that dictate treatment response and patient outcomes. Of these, basal-like breast cancer is an aggressive subtype controlled by a pluripotency-enforcing transcriptome. Meanwhile, the more differentiated luminal subtype of breast cancer is driven by an estrogen receptor-dominated transcriptome that underlies its responsiveness to antihormone therapies and conveys improved patient outcomes. Despite the clear differences in molecular signatures, the genesis of each subtype from normal mammary epithelial cells remains unclear. Recent technical advances have revealed key distinctions in chromatin folding and organization between subtypes that could underlie their transcriptomic and, hence, phenotypic differences. These studies also suggest that proteins controlling particular chromatin states may be useful targets for treating aggressive disease. In this review, we explore the current state of understanding of chromatin architecture in breast cancer subtypes and its potential role in defining their phenotypic characteristics.


Asunto(s)
Neoplasias de la Mama , Humanos , Femenino , Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Línea Celular Tumoral , Mama/metabolismo , Cromatina/genética , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica
13.
Cancer Res ; 83(7): 997-1015, 2023 04 04.
Artículo en Inglés | MEDLINE | ID: mdl-36696357

RESUMEN

Breast cancer subtypes and their phenotypes parallel different stages of the mammary epithelial cell developmental hierarchy. Discovering mechanisms that control lineage identity could provide novel avenues for mitigating disease progression. Here we report that the transcriptional corepressor TLE3 is a guardian of luminal cell fate in breast cancer and operates independently of the estrogen receptor. In luminal breast cancer, TLE3 actively repressed the gene-expression signature associated with highly aggressive basal-like breast cancers (BLBC). Moreover, maintenance of the luminal lineage depended on the appropriate localization of TLE3 to its transcriptional targets, a process mediated by interactions with FOXA1. By repressing genes that drive BLBC phenotypes, including SOX9 and TGFß2, TLE3 prevented the acquisition of a hybrid epithelial-mesenchymal state and reduced metastatic capacity and aggressive cellular behaviors. These results establish TLE3 as an essential transcriptional repressor that sustains the more differentiated and less metastatic nature of luminal breast cancers. Approaches to induce TLE3 expression could promote the acquisition of less aggressive, more treatable disease states to extend patient survival. SIGNIFICANCE: Transcriptional corepressor TLE3 actively suppresses SOX9 and TGFß transcriptional programs to sustain the luminal lineage identity of breast cancer cells and to inhibit metastatic progression.


Asunto(s)
Neoplasias , Factores de Transcripción , Diferenciación Celular , Proteínas Co-Represoras/genética , Receptores de Estrógenos/metabolismo , Factor de Crecimiento Transformador beta , Neoplasias de la Mama/metabolismo , Humanos
14.
Biol Reprod ; 87(2): 41, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22649074

RESUMEN

Activin is a well-established modulator of male and female reproduction that stimulates the synthesis and secretion of follicle-stimulating hormone. Nonpituitary effects of activin have also been reported, although the paracrine actions of this growth factor in several reproductive tissues are not well understood. To identify the paracrine functions of activin during mammary gland morphogenesis and tumor progression, we produced transgenic mice that overexpress follistatin (FST), an intrinsic inhibitor of activin, under control of the mouse mammary tumor virus (MMTV) promoter. Although the MMTV-Fst mice were constructed to assess the role of activin in females, expression of the transgene was also observed in the testes and epididymides of males. While all 17 transgenic founder males exhibited copulatory behavior and produced vaginal plugs in females, only one produced live offspring. In contrast, transgenic females were fertile, permitting expansion of transgenic mouse lines. Light and transmission electron microscopic examination of the transgenic testes and epididymides revealed impairment of fluid resorption and sperm transit in the efferent ducts and initial segment of the epididymis, as indicated by accumulation of fluid and sperm stasis. Consequently, a variety of degenerative lesions were observed in the seminiferous epithelium, such as vacuolation and early stages of mineralization and fibrosis. Sperm collected from the caudae epididymidis of MMTV-Fst males had detached heads and were immotile. Together, these data reveal that activin signaling is essential for normal testicular excurrent duct function and that its blockade impairs fertility. These results also suggest that selective inhibitors of activin signaling may provide a useful approach for the development of male contraceptives without compromising androgen synthesis and actions.


Asunto(s)
Activinas/metabolismo , Modelos Animales de Enfermedad , Epidídimo/metabolismo , Folistatina/metabolismo , Infertilidad Masculina/metabolismo , Animales , Receptor alfa de Estrógeno/metabolismo , Femenino , Gonadotropinas Hipofisarias/metabolismo , Infertilidad Masculina/patología , Infertilidad Masculina/fisiopatología , Masculino , Virus del Tumor Mamario del Ratón , Ratones , Ratones Transgénicos , Tamaño de los Órganos , Fenotipo , Hipófisis/metabolismo , Regiones Promotoras Genéticas , Testículo/metabolismo , Testículo/patología , Testículo/fisiopatología , Testosterona/sangre
15.
Proc Natl Acad Sci U S A ; 106(26): 10696-701, 2009 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-19541653

RESUMEN

PACT is a double-stranded RNA-binding protein that also binds and activates the latent protein kinase, PKR, which plays a major role in cellular antiviral defense in mammals. For evaluating PACT's contribution to the innate immune system, Pact(-/-) mice have been generated; these mice exhibit notable developmental abnormalities including microtia, with craniofacial, ear, and hearing defects. Here we report that, in addition, Pact(-/-) mice had smaller body size and fertility defects, both of which were caused by defective pituitary functions. Pact(-/-) mice exhibited anterior pituitary lobe (AL) hypoplasia, which developed postnatally, when the second phase of pituitary expansion occurs. Among the 5 cell types in AL, the numbers of corticotrophs, gonadotrophs, and somatotrophs were equally decreased in Pact(-/-) mice with a greater impact on lactotrophs and a lesser impact on thyrotrophs. PACT mRNA and protein were highly expressed in the pituitary of wild-type (Wt) mice during the postnatal wave of AL proliferation, the same period in which the hypoplasia developed in Pact(-/-) mice. During this time, the pituitaries of Pact(-/-) mice did not exhibit significantly increased apoptosis compared with Wt mice but showed a decrease in cell proliferation. The inhibition of cell proliferation observed in vivo could be recapitulated in vitro in GH3 somato/lactotroph and LbetaT2 gonadotroph cell lines; knockdown of PACT expression with siRNA diminished the rate of proliferation of these cells. Our study revealed a physiologically significant role for PACT in cell proliferation and an essential role of a dsRNA-binding protein in mammalian pituitary expansion.


Asunto(s)
Proliferación Celular , Hipófisis/metabolismo , ARN Bicatenario/metabolismo , Proteínas de Unión al ARN/metabolismo , Animales , Animales Recién Nacidos , Western Blotting , Tamaño Corporal/genética , Tamaño Corporal/fisiología , Peso Corporal/genética , Peso Corporal/fisiología , Línea Celular , Femenino , Hormona del Crecimiento/genética , Hormona del Crecimiento/metabolismo , Infertilidad/genética , Infertilidad/fisiopatología , Masculino , Glándulas Mamarias Animales/anomalías , Ratones , Ratones Noqueados , Ovario/anomalías , Hipófisis/patología , Embarazo , Interferencia de ARN , Proteínas de Unión al ARN/genética , Ratas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores de Tiempo
16.
J Biol Chem ; 285(25): 19106-15, 2010 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-20424164

RESUMEN

Epidermal growth factors and their receptors (EGFRs) promote breast cancer cell proliferation and can drive tumorigenesis. However, the molecular mechanisms that mediate these effects are incompletely understood. We previously showed that mammary tumor development in the mouse model of breast cancer MMTV-neu, a model characterized by amplification of the EGFR ErbB2 in mammary tissue, correlates with a marked up-regulation of fatty acid-binding protein 5 (FABP5). FABP5 functions to deliver ligands to and enhance the transcriptional activity of the nuclear receptor peroxisome proliferator-activated receptor beta/delta (PPARbeta/delta), a receptor whose target genes include genes involved in cell growth and survival. We show here that in MCF-7 mammary carcinoma cells, EGFR signaling directly up-regulates the expression of FABP5. The data demonstrate that treatment of these cells with the EGFR ligand heregulin-beta1 signals through the ERK and the phophatidylinositol-3-kinase cascades, resulting in activation of the transcription factor NF-kappaB. In turn, NF-kappaB induces the expression of FABP5 through two cognate response elements in the promoter of this gene. The observations further demonstrate that FABP5 and PPARbeta/delta are critical mediators of the ability of EGFR to enhance cell proliferation, indicating that this transcriptional pathway plays a key role in EGFR-induced tumorigenesis. Additional observations indicate that the expression of FABP5 is down-regulated by the Krüppel-like factor KLF2, suggesting a tumor suppressor activity for this factor.


Asunto(s)
Carcinoma/metabolismo , Proteínas de Unión a Ácidos Grasos/fisiología , Regulación Neoplásica de la Expresión Génica , PPAR delta/metabolismo , PPAR-beta/metabolismo , Línea Celular Tumoral , Núcleo Celular/metabolismo , Proliferación Celular , Humanos , Péptidos y Proteínas de Señalización Intercelular , Ligandos , Lípidos/química , Modelos Biológicos , FN-kappa B/metabolismo , Neurregulina-1/metabolismo
17.
J Biol Chem ; 285(38): 29491-501, 2010 Sep 17.
Artículo en Inglés | MEDLINE | ID: mdl-20595387

RESUMEN

Breast cancers that overexpress the receptor tyrosine kinase ErbB2/HER2/Neu result in poor patient outcome because of extensive metastatic progression. Herein, we delineate a molecular mechanism that may govern this malignant phenotype. ErbB2 induction of migration requires activation of the small GTPases Rac1 and Cdc42. The ability of ErbB2 to activate these small GTPases necessitated expression of p120 catenin, which is itself up-regulated by signaling through ErbB2 and the tyrosine kinase Src. Silencing p120 in ErbB2-dependent breast cancer cell lines dramatically inhibited migration and invasion as well as activation of Rac1 and Cdc42. In contrast, overexpression of constitutively active mutants of these GTPases reversed the effects of p120 silencing. Lastly, ectopic expression of p120 promoted migration and invasion and potentiated metastatic progression of a weakly metastatic, ErbB2-dependent breast cancer cell line. These results suggest that p120 acts as an obligate intermediate between ErbB2 and Rac1/Cdc42 to modulate the metastatic potential of breast cancer cells.


Asunto(s)
Neoplasias de la Mama/metabolismo , Cateninas/metabolismo , Receptor ErbB-2/metabolismo , Proteína de Unión al GTP cdc42/metabolismo , Proteína de Unión al GTP rac1/metabolismo , Animales , Western Blotting , Neoplasias de la Mama/genética , Cateninas/genética , Línea Celular , Línea Celular Tumoral , Movimiento Celular/genética , Movimiento Celular/fisiología , Femenino , Técnica del Anticuerpo Fluorescente , Humanos , Inmunohistoquímica , Técnicas In Vitro , Ratones , Ratones Desnudos , Receptor ErbB-2/genética , Cicatrización de Heridas/genética , Cicatrización de Heridas/fisiología , Proteína de Unión al GTP cdc42/genética , Proteína de Unión al GTP rac1/genética , Catenina delta
18.
J Pathol ; 222(3): 271-81, 2010 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-20814902

RESUMEN

The LIM-only protein, LMO4, is a transcriptional modulator overexpressed in breast cancer. It is oncogenic in murine mammary epithelium and is required for G2/M progression of ErbB2-dependent cells as well as growth and invasion of other breast cancer cell types. However, the mechanisms underlying the oncogenic activity of LMO4 remain unclear. Herein, we show that LMO4 is expressed in all breast cancer subtypes examined and its expression level correlates with the degree of proliferation of such tumours. In addition, we have determined that LMO4 silencing induces G2/M arrest in cells from various breast cancer subtypes, suggesting that LMO4 action in the cell cycle is not restricted to a single breast cancer subtype. This arrest was accompanied by increased cell death, amplification of centrosomes, and formation of abnormal mitotic spindles. Consistent with its ability to positively and negatively regulate the formation of active transcription complexes, overexpression of LMO4 also resulted in an increase in centrosome number. Centrosome amplification has been shown to prolong the G2/M phase of the cell cycle and induce apoptosis; thus, we conclude that supernumerary centrosomes mediate the G2/M arrest and cell death in LMO4-deficient cells. Furthermore, the correlation of centrosome amplification with genomic instability suggests that the impact of dysregulated LMO4 on the centrosome cycle may promote LMO4-induced tumour formation.


Asunto(s)
Neoplasias de la Mama/metabolismo , Centrosoma/patología , Proteínas de Homeodominio/biosíntesis , Huso Acromático/patología , Factores de Transcripción/biosíntesis , Proteínas Adaptadoras Transductoras de Señales , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Ciclo Celular/fisiología , Centrosoma/metabolismo , Femenino , Genes BRCA1 , Proteínas de Homeodominio/genética , Humanos , Proteínas con Dominio LIM , Índice Mitótico , Mutación , Proteínas de Neoplasias/biosíntesis , Proteínas de Neoplasias/genética , ARN Mensajero/genética , ARN Neoplásico/genética , Receptores de Estrógenos/deficiencia , Huso Acromático/metabolismo , Factores de Transcripción/genética
19.
Cancers (Basel) ; 13(20)2021 Oct 17.
Artículo en Inglés | MEDLINE | ID: mdl-34680352

RESUMEN

The pioneering function of FOXA1 establishes estrogen-responsive transcriptomes in luminal breast cancer. Dysregulated FOXA1 chromatin occupancy through focal amplification, mutation, or cofactor recruitment modulates estrogen receptor (ER) transcriptional programs and drives endocrine-resistant disease. However, ER is not the sole nuclear receptor (NR) expressed in breast cancers, nor is it the only NR for which FOXA1 serves as a licensing factor. Receptors for androgens, glucocorticoids, and progesterone are also found in the majority of breast cancers, and their functions are also impacted by FOXA1. These NRs interface with ER transcriptional programs and, depending on their activation level, can reprogram FOXA1-ER cistromes. Thus, NR interplay contributes to endocrine therapy response and resistance and may provide a vulnerability for future therapeutic benefit in patients. Herein, we review what is known regarding FOXA1 regulation of NR function in breast cancer in the context of cell identity, endocrine resistance, and NR crosstalk in breast cancer progression and treatment.

20.
Cancer Res ; 80(8): 1693-1706, 2020 04 15.
Artículo en Inglés | MEDLINE | ID: mdl-32054769

RESUMEN

A significant therapeutic challenge for patients with cancer is resistance to chemotherapies such as taxanes. Overexpression of LIN9, a transcriptional regulator of cell-cycle progression, occurs in 65% of patients with triple-negative breast cancer (TNBC), a disease commonly treated with these drugs. Here, we report that LIN9 is further elevated with acquisition of taxane resistance. Inhibiting LIN9 genetically or by suppressing its expression with a global BET inhibitor restored taxane sensitivity by inducing mitotic progression errors and apoptosis. While sustained LIN9 is necessary to maintain taxane resistance, there are no inhibitors that directly repress its function. Hence, we sought to discover a druggable downstream transcriptional target of LIN9. Using a computational approach, we identified NIMA-related kinase 2 (NEK2), a regulator of centrosome separation that is also elevated in taxane-resistant cells. High expression of NEK2 was predictive of low survival rates in patients who had residual disease following treatment with taxanes plus an anthracycline, suggesting a role for this kinase in modulating taxane sensitivity. Like LIN9, genetic or pharmacologic blockade of NEK2 activity in the presence of paclitaxel synergistically induced mitotic abnormalities in nearly 100% of cells and completely restored sensitivity to paclitaxel, in vitro. In addition, suppressing NEK2 activity with two distinct small molecules potentiated taxane response in multiple in vivo models of TNBC, including a patient-derived xenograft, without inducing toxicity. These data demonstrate that the LIN9/NEK2 pathway is a therapeutically targetable mediator of taxane resistance that can be leveraged to improve response to this core chemotherapy. SIGNIFICANCE: Resistance to chemotherapy is a major hurdle for treating patients with cancer. Combining NEK2 inhibitors with taxanes may be a viable approach for improving patient outcomes by enhancing mitotic defects induced by taxanes alone.


Asunto(s)
Resistencia a Antineoplásicos/efectos de los fármacos , Mitosis/efectos de los fármacos , Quinasas Relacionadas con NIMA/antagonistas & inhibidores , Proteínas Nucleares/antagonistas & inhibidores , Paclitaxel/farmacología , Taxoides/farmacología , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Proteínas Supresoras de Tumor/antagonistas & inhibidores , Antineoplásicos/administración & dosificación , Antineoplásicos/farmacología , Apoptosis , Línea Celular Tumoral , Senescencia Celular , Centrosoma/enzimología , Femenino , Regulación Neoplásica de la Expresión Génica , Silenciador del Gen , Xenoinjertos , Humanos , Mitosis/genética , Quinasas Relacionadas con NIMA/metabolismo , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/metabolismo , Proteínas Nucleares/metabolismo , Paclitaxel/administración & dosificación , Tasa de Supervivencia , Taxoides/administración & dosificación , Neoplasias de la Mama Triple Negativas/metabolismo , Neoplasias de la Mama Triple Negativas/mortalidad , Ensayo de Tumor de Célula Madre , Proteínas Supresoras de Tumor/metabolismo , Regulación hacia Arriba
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