RESUMO
Notwithstanding the positive clinical impact of endocrine therapies in estrogen receptor-alpha (ERα)-positive breast cancer, de novo and acquired resistance limits the therapeutic lifespan of existing drugs. Taking the position that resistance is nearly inevitable, we undertook a study to identify and exploit targetable vulnerabilities that were manifest in endocrine therapy-resistant disease. Using cellular and mouse models of endocrine therapy-sensitive and endocrine therapy-resistant breast cancer, together with contemporary discovery platforms, we identified a targetable pathway that is composed of the transcription factors FOXA1 and GRHL2, a coregulated target gene, the membrane receptor LYPD3, and the LYPD3 ligand, AGR2. Inhibition of the activity of this pathway using blocking antibodies directed against LYPD3 or AGR2 inhibits the growth of endocrine therapy-resistant tumors in mice, providing the rationale for near-term clinical development of humanized antibodies directed against these proteins.
Assuntos
Fator 3-alfa Nuclear de Hepatócito/metabolismo , Neoplasias Mamárias Experimentais/metabolismo , Fatores de Transcrição/metabolismo , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/uso terapêutico , Moléculas de Adesão Celular/imunologia , Moléculas de Adesão Celular/metabolismo , Resistencia a Medicamentos Antineoplásicos , Receptor alfa de Estrogênio/genética , Feminino , Proteínas Ligadas por GPI/imunologia , Proteínas Ligadas por GPI/metabolismo , Humanos , Células MCF-7 , Neoplasias Mamárias Experimentais/tratamento farmacológico , Neoplasias Mamárias Experimentais/genética , Camundongos , Mucoproteínas/imunologia , Mucoproteínas/metabolismo , Proteínas Oncogênicas/imunologia , Proteínas Oncogênicas/metabolismoRESUMO
Estrogen promotes growth of estrogen receptor-positive (ER+) breast tumors. However, epidemiological studies examining the prognostic characteristics of breast cancer in postmenopausal women receiving hormone replacement therapy reveal a significant decrease in tumor dissemination, suggesting that estrogen has potential protective effects against cancer cell invasion. Here, we show that estrogen suppresses invasion of ER+ breast cancer cells by increasing transcription of the Ena/VASP protein, EVL, which promotes the generation of suppressive cortical actin bundles that inhibit motility dynamics, and is crucial for the ER-mediated suppression of invasion in vitro and in vivo. Interestingly, despite its benefits in suppressing tumor growth, anti-estrogenic endocrine therapy decreases EVL expression and increases local invasion in patients. Our results highlight the dichotomous effects of estrogen on tumor progression and suggest that, in contrast to its established role in promoting growth of ER+ tumors, estrogen has a significant role in suppressing invasion through actin cytoskeletal remodeling.
Assuntos
Citoesqueleto de Actina/química , Actinas/química , Neoplasias da Mama/patologia , Receptor alfa de Estrogênio/química , Estrogênios/química , Invasividade Neoplásica , Animais , Células CACO-2 , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Proliferação de Células , Cães , Estradiol/química , Feminino , Perfilação da Expressão Gênica , Células HEK293 , Humanos , Linfonodos/patologia , Células MCF-7 , Células Madin Darby de Rim Canino , Camundongos , Camundongos Endogâmicos NOD , Metástase Neoplásica , Transcrição GênicaRESUMO
Merkel cell carcinoma (MCC) frequently contains integrated copies of Merkel cell polyomavirus DNA that express a truncated form of Large T antigen (LT) and an intact Small T antigen (ST). While LT binds RB and inactivates its tumor suppressor function, it is less clear how ST contributes to MCC tumorigenesis. Here we show that ST binds specifically to the MYC homolog MYCL (L-MYC) and recruits it to the 15-component EP400 histone acetyltransferase and chromatin remodeling complex. We performed a large-scale immunoprecipitation for ST and identified co-precipitating proteins by mass spectrometry. In addition to protein phosphatase 2A (PP2A) subunits, we identified MYCL and its heterodimeric partner MAX plus the EP400 complex. Immunoprecipitation for MAX and EP400 complex components confirmed their association with ST. We determined that the ST-MYCL-EP400 complex binds together to specific gene promoters and activates their expression by integrating chromatin immunoprecipitation with sequencing (ChIP-seq) and RNA-seq. MYCL and EP400 were required for maintenance of cell viability and cooperated with ST to promote gene expression in MCC cell lines. A genome-wide CRISPR-Cas9 screen confirmed the requirement for MYCL and EP400 in MCPyV-positive MCC cell lines. We demonstrate that ST can activate gene expression in a EP400 and MYCL dependent manner and this activity contributes to cellular transformation and generation of induced pluripotent stem cells.
Assuntos
Antígenos Virais de Tumores/metabolismo , Carcinoma de Célula de Merkel/virologia , Transformação Celular Viral/fisiologia , DNA Helicases/metabolismo , Proteínas de Ligação a DNA/metabolismo , Regulação Neoplásica da Expressão Gênica/fisiologia , Proteínas Proto-Oncogênicas c-myc/metabolismo , Antígenos Transformantes de Poliomavirus/metabolismo , Carcinoma de Célula de Merkel/genética , Carcinoma de Célula de Merkel/metabolismo , Linhagem Celular Tumoral , Humanos , Immunoblotting , Imunoprecipitação , Poliomavírus das Células de Merkel , Infecções por Polyomavirus/complicações , Infecções por Polyomavirus/genética , Infecções por Polyomavirus/metabolismo , Infecções Tumorais por Vírus/complicações , Infecções Tumorais por Vírus/genética , Infecções Tumorais por Vírus/metabolismoRESUMO
Targeting the activation function-1 (AF-1) domain located in the N-terminus of the androgen receptor (AR) is an attractive therapeutic alternative to the current approaches to inhibit AR action in prostate cancer (PCa). Here we show that the AR AF-1 is bound by the cochaperone Bag-1L. Mutations in the AR interaction domain or loss of Bag-1L abrogate AR signaling and reduce PCa growth. Clinically, Bag-1L protein levels increase with progression to castration-resistant PCa (CRPC) and high levels of Bag-1L in primary PCa associate with a reduced clinical benefit from abiraterone when these tumors progress. Intriguingly, residues in Bag-1L important for its interaction with the AR AF-1 are within a potentially druggable pocket, implicating Bag-1L as a potential therapeutic target in PCa.
Assuntos
Antagonistas de Receptores de Andrógenos/metabolismo , Proteínas de Ligação a DNA/antagonistas & inibidores , Proteínas de Ligação a DNA/metabolismo , Neoplasias da Próstata/patologia , Receptores Androgênicos/metabolismo , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/metabolismo , Humanos , Masculino , Neoplasias da Próstata/terapia , Ligação Proteica , Mapas de Interação de ProteínasRESUMO
Women in North America have a one in eight lifetime risk of developing breast cancer (BC), and a significant proportion of these individuals will develop recurrent BC and will eventually succumb to the disease. Metastatic, therapy-resistant BC cells are refractory to cell death induced by multiple stresses. Here, we document that the vitamin D receptor (VDR) acts as a master transcriptional regulator of autophagy. Activation of the VDR by vitamin D induces autophagy and an autophagic transcriptional signature in BC cells that correlates with increased survival in patients; strikingly, this signature is present in the normal mammary gland and is progressively lost in patients with metastatic BC. A number of epidemiological studies have shown that sufficient vitamin D serum levels might be protective against BC. We observed that dietary vitamin D supplementation in mice increases basal levels of autophagy in the normal mammary gland, highlighting the potential of vitamin D as a cancer-preventive agent. These findings point to a role of vitamin D and the VDR in modulating autophagy and cell death in both the normal mammary gland and BC cells.
Assuntos
Autofagia , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Mama/metabolismo , Receptores de Calcitriol/genética , Motivos de Aminoácidos , Animais , Autofagia/efeitos dos fármacos , Autofagia/genética , Sítios de Ligação , Biomarcadores , Neoplasias da Mama/patologia , Neoplasias da Mama/ultraestrutura , Linhagem Celular Tumoral , Modelos Animais de Doenças , Progressão da Doença , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Redes Reguladoras de Genes , Xenoenxertos , Humanos , Lisossomos/metabolismo , Lisossomos/ultraestrutura , Camundongos , Modelos Biológicos , Matrizes de Pontuação de Posição Específica , Ligação Proteica , Receptores de Calcitriol/metabolismo , Vitamina D/metabolismo , Vitamina D/farmacologiaRESUMO
Regulation of lineage-restricted transcription factors has been shown to influence malignant transformation in several types of cancer. Whether similar mechanisms are involved in ovarian cancer pathogenesis is unknown. PAX8 is a nuclear transcription factor that controls the embryologic development of the Müllerian system, including the fallopian tubes. Recent studies have shown that fallopian tube secretory epithelial cells (FTSECs) give rise to the most common form of ovarian cancer, high-grade serous ovarian carcinomas (HGSOCs). We designed the present study in order to understand whether changes in gene expression between FTSECs and HGSOCs relate to alterations in PAX8 binding to chromatin. Using whole transcriptome shotgun sequencing (RNA-Seq) after PAX8 knockdown and ChIP-Seq, we show that FTSECs and HGSOCs are distinguished by marked reprogramming of the PAX8 cistrome. Genes that are significantly altered between FTSECs and HGSOCs are enriched near PAX8 binding sites. These sites are also near TEAD binding sites, and these transcriptional changes may be related to PAX8 interactions with the TEAD/YAP1 signaling pathway. These data suggest that transcriptional changes after transformation in ovarian cancer are closely related to epigenetic remodeling in lineage-specific transcription factors.
RESUMO
The TMPRSS2:ERG gene fusion is common in androgen receptor (AR) positive prostate cancers, yet its function remains poorly understood. From a screen for functionally relevant ERG interactors, we identify the arginine methyltransferase PRMT5. ERG recruits PRMT5 to AR-target genes, where PRMT5 methylates AR on arginine 761. This attenuates AR recruitment and transcription of genes expressed in differentiated prostate epithelium. The AR-inhibitory function of PRMT5 is restricted to TMPRSS2:ERG-positive prostate cancer cells. Mutation of this methylation site on AR results in a transcriptionally hyperactive AR, suggesting that the proliferative effects of ERG and PRMT5 are mediated through attenuating AR's ability to induce genes normally involved in lineage differentiation. This provides a rationale for targeting PRMT5 in TMPRSS2:ERG positive prostate cancers. Moreover, methylation of AR at arginine 761 highlights a mechanism for how the ERG oncogene may coax AR towards inducing proliferation versus differentiation.
Assuntos
Células Epiteliais/metabolismo , Regulação Neoplásica da Expressão Gênica , Proteínas de Fusão Oncogênica/genética , Proteína-Arginina N-Metiltransferases/genética , Receptores Androgênicos/genética , Serina Endopeptidases/genética , Sequência de Bases , Diferenciação Celular , Linhagem Celular Tumoral , Proliferação de Células , Células Epiteliais/patologia , Humanos , Masculino , Metilação , Modelos Moleculares , Mutação , Proteínas de Fusão Oncogênica/metabolismo , Próstata/metabolismo , Próstata/patologia , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Multimerização Proteica , Estrutura Secundária de Proteína , Proteína-Arginina N-Metiltransferases/antagonistas & inibidores , Proteína-Arginina N-Metiltransferases/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Receptores Androgênicos/química , Receptores Androgênicos/metabolismo , Serina Endopeptidases/metabolismo , Transdução de Sinais , Regulador Transcricional ERG/genética , Regulador Transcricional ERG/metabolismoRESUMO
Among the genes regulated by estrogen receptor (ER) are miRNAs that play a role in breast cancer signaling pathways. To determine whether miRNAs are involved in ER-positive breast cancer progression to hormone independence, we profiled the expression of 800 miRNAs in the estrogen-dependent human breast cancer cell line MCF7 and its estrogen-independent derivative MCF7:2A (MCF7:2A) using NanoString. We found 78 miRNAs differentially expressed between the two cell lines, including a cluster comprising let-7c, miR99a, and miR125b, which is encoded in an intron of the long noncoding RNA LINC00478. These miRNAs are ER targets in MCF7 cells, and nearby ER binding and their expression are significantly decreased in MCF7:2A cells. The expression of these miRNAs was interrogated in patient samples profiled in The Cancer Genome Atlas (TCGA). Among luminal tumors, these miRNAs are expressed at higher levels in luminal A versus B tumors. Although their expression is uniformly low in luminal B tumors, they are lost only in a subset of luminal A patients. Interestingly, this subset with low expression of these miRNAs had worse overall survival compared with luminal A patients with high expression. We confirmed that miR125b directly targets HER2 and that let-7c also regulates HER2 protein expression. In addition, HER2 protein expression and activity are negatively correlated with let-7c expression in TCGA. In summary, we identified an ER-regulated miRNA cluster that regulates HER2, is lost with progression to estrogen independence, and may serve as a biomarker of poor outcome in ER(+) luminal A breast cancer patients.
Assuntos
Neoplasias da Mama/enzimologia , Neoplasias da Mama/genética , MicroRNAs/biossíntese , Receptor ErbB-2/metabolismo , Neoplasias da Mama/patologia , Processos de Crescimento Celular/fisiologia , Regulação para Baixo , Feminino , Humanos , Células MCF-7 , MicroRNAs/genética , Receptor ErbB-2/antagonistas & inibidores , Receptor ErbB-2/biossíntese , Receptores de Estrogênio/metabolismo , TransfecçãoRESUMO
Estrogen has vascular protective effects in premenopausal women and in women younger than 60 years who are receiving hormone replacement therapy. However, estrogen also increases the risks of breast and uterine cancers and of venous thromboses linked to up-regulation of coagulation factors in the liver. In mouse models, the vasculoprotective effects of estrogen are mediated by the estrogen receptor α (ERα) transcription factor. Here, through next-generation sequencing approaches, we show that almost all of the genes regulated by 17ß-estradiol (E2) differ between mouse aorta and mouse liver, ex vivo, and that this difference is associated with a distinct genomewide distribution of ERα on chromatin. Bioinformatic analysis of E2-regulated promoters and ERα binding site sequences identify several transcription factors that may determine the tissue specificity of ERα binding and E2-regulated genes, including the enrichment of NF-κB, AML1, and AP1 sites in the promoters of E2 down-regulated inflammatory genes in aorta but not liver. The possible vascular-specific functions of these factors suggest ways in which the protective effects of estrogen could be promoted in the vasculature without incurring negative effects in other tissues.
Assuntos
Aorta/metabolismo , Receptor alfa de Estrogênio/metabolismo , Estrogênios/fisiologia , Fígado/metabolismo , Animais , Sequência de Bases , Doenças Cardiovasculares/metabolismo , Cromatina/metabolismo , Sequência Consenso , Estradiol/fisiologia , Feminino , Regulação da Expressão Gênica , Camundongos Endogâmicos C57BL , Especificidade de Órgãos , Regiões Promotoras Genéticas , Ligação Proteica , Transdução de SinaisRESUMO
More than two-thirds of breast cancers express the estrogen receptor (ER) and depend on estrogen for growth and survival. Therapies targeting ER function, including aromatase inhibitors that block the production of estrogens and ER antagonists that alter ER transcriptional activity, play a central role in the treatment of ER+ breast cancers of all stages. In contrast to ER- breast cancers, which frequently harbor mutations in the p53 tumor suppressor, ER+ breast cancers are predominantly wild type for p53. Despite harboring wild-type p53, ER+ breast cancer cells are resistant to chemotherapy-induced apoptosis in the presence of estrogen. Using genome-wide approaches, we have addressed the mechanism by which ER antagonizes the proapoptotic function of p53. Interestingly, both ER agonists such as estradiol and the selective ER modulator (SERM) tamoxifen promote p53 antagonism. In contrast, the full ER antagonist fulvestrant blocks the ability of ER to inhibit p53-mediated cell death. This inhibition works through a mechanism involving the modulation of a subset of p53 and ER target genes that can predict the relapse-free survival of patients with ER+ breast cancer. These findings suggest an improved strategy for the treatment of ER+ breast cancer using antagonists that completely block ER action together with drugs that activate p53-mediated cell death.
Assuntos
Apoptose/fisiologia , Neoplasias da Mama/patologia , Receptores de Estrogênio/fisiologia , Proteína Supressora de Tumor p53/fisiologia , Neoplasias da Mama/fisiopatologia , Feminino , HumanosRESUMO
Estrogen receptor α (ERα) expression in breast cancer is predictive of response to endocrine therapy; however, resistance is common in ERα-positive tumors that overexpress the growth factor receptor ERBB2. Even in the absence of estrogen, ERα can be activated by growth factors, including the epidermal growth factor (EGF). EGF induces a transcriptional program distinct from estrogen; however, the mechanism of the stimulus-specific response is unknown. Here we show that the EGF-induced ERα genomic targets, its cistromes, are distinct from those induced by estrogen in a process dependent on the transcription factor AP-1. The EGF-induced ERα cistrome specifically regulates genes found overexpressed in ERBB2-positive human breast cancers. This provides a potential molecular explanation for the endocrine therapy resistance seen in ERα-positive breast cancers that overexpress ERBB2. These results suggest a central role for ERα in hormone-refractory breast tumors dependent on growth factor pathway activation and favors the development of therapeutic strategies completely antagonizing ERα, as opposed to blocking its estrogen responsiveness alone.