RESUMO
The MYC axis is disrupted in cancer, predominantly through activation of the MYC family oncogenes but also through inactivation of the MYC partner MAX or of the MAX partner MGA. MGA and MAX are also members of the polycomb repressive complex, ncPRC1.6. Here, we use genetically modified MAX-deficient small-cell lung cancer (SCLC) cells and carry out genome-wide and proteomics analyses to study the tumor suppressor function of MAX. We find that MAX mutant SCLCs have ASCL1 or NEUROD1 or combined ASCL1/NEUROD1 characteristics and lack MYC transcriptional activity. MAX restitution triggers prodifferentiation expression profiles that shift when MAX and oncogenic MYC are coexpressed. Although ncPRC1.6 can be formed, the lack of MAX restricts global MGA occupancy, selectively driving its recruitment toward E2F6-binding motifs. Conversely, MAX restitution enhances MGA occupancy to repress genes involved in different functions, including stem cell and DNA repair/replication. Collectively, these findings reveal that MAX mutant SCLCs have either ASCL1 or NEUROD1 or combined characteristics and are MYC independent and exhibit deficient ncPRC1.6-mediated gene repression.
Assuntos
Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Regulação Neoplásica da Expressão Gênica , Neoplasias Pulmonares/patologia , Proteínas do Grupo Polycomb/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Carcinoma de Pequenas Células do Pulmão/patologia , Apoptose , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proliferação de Células , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Proteínas do Grupo Polycomb/genética , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas c-myc/genética , Carcinoma de Pequenas Células do Pulmão/genética , Carcinoma de Pequenas Células do Pulmão/metabolismo , Células Tumorais CultivadasRESUMO
The MAX network transcriptional repressor (MNT) is an MXD family transcription factor of the basic helix-loop-helix (bHLH) family. MNT dimerizes with another transcriptional regulator, MYC-associated factor X (MAX), and down-regulates genes by binding to E-boxes. MAX also dimerizes with MYC, an oncogenic bHLH transcription factor. Upon E-box binding, the MYC-MAX dimer activates gene expression. MNT also binds to the MAX dimerization protein MLX (MLX), and MNT-MLX and MNT-MAX dimers co-exist. However, all MNT functions have been attributed to MNT-MAX dimers, and no functions of the MNT-MLX dimer have been described. MNT's biological role has been linked to its function as a MYC oncogene modulator, but little is known about its regulation. We show here that MNT localizes to the nucleus of MAX-expressing cells and that MNT-MAX dimers bind and repress the MNT promoter, an effect that depends on one of the two E-boxes on this promoter. In MAX-deficient cells, MNT was overexpressed and redistributed to the cytoplasm. Interestingly, MNT was required for cell proliferation even in the absence of MAX. We show that in MAX-deficient cells, MNT binds to MLX, but also forms homodimers. RNA-sequencing experiments revealed that MNT regulates the expression of several genes even in the absence of MAX, with many of these genes being involved in cell cycle regulation and DNA repair. Of note, MNT-MNT homodimers regulated the transcription of some genes involved in cell proliferation. The tight regulation of MNT and its functionality even without MAX suggest a major role for MNT in cell proliferation.
Assuntos
Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Proteínas Repressoras/genética , Transcrição Gênica , Sequência de Aminoácidos/genética , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/química , Proliferação de Células/genética , Regulação da Expressão Gênica/genética , Redes Reguladoras de Genes/genética , Sequências Hélice-Alça-Hélice/genética , Humanos , Regiões Promotoras Genéticas , Multimerização Proteica/genética , Proteínas Proto-Oncogênicas c-myc/química , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Repressoras/químicaRESUMO
SMARCA4 is the catalytic subunit of the SWI/SNF chromatin-remodeling complex, which alters the interactions between DNA and histones and modifies the availability of the DNA for transcription. The latest deep sequencing of tumor genomes has reinforced the important and ubiquitous tumor suppressor role of the SWI/SNF complex in cancer. However, although SWI/SNF complex plays a key role in gene expression, the regulation of this complex itself is poorly understood. Significantly, an understanding of the regulation of SMARCA4 expression has gained in importance due to recent proposals incorporating it in therapeutic strategies that use synthetic lethal interactions between SMARCA4-MAX and SMARCA4-SMARCA2. In this report, we found that the loss of expression of SMARCA4 observed in some primary lung tumors, whose mechanism was largely unknown, can be explained, at least partially by the activity of microRNAs (miRNAs). We reveal that SMARCA4 expression is regulated by miR-101, miR-199 and especially miR-155 through their binding to two alternative 3'UTRs. Importantly, our experiments suggest that the oncogenic properties of miR-155 in lung cancer can be largely explained by its role inhibiting SMARCA4. This new discovered functional relationship could explain the poor prognosis displayed by patients that independently have high miR-155 and low SMARCA4 expression levels. In addition, these results could lead to application of incipient miRNA technology to the aforementioned synthetic lethal therapeutic strategies.
Assuntos
DNA Helicases/metabolismo , Regulação Neoplásica da Expressão Gênica , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/genética , MicroRNAs/metabolismo , Proteínas Nucleares/metabolismo , Fatores de Transcrição/metabolismo , Domínio Catalítico , Linhagem Celular Tumoral , Núcleo Celular/genética , Proliferação de Células , Montagem e Desmontagem da Cromatina , Clonagem Molecular , DNA Helicases/genética , Células HeLa , Sequenciamento de Nucleotídeos em Larga Escala , Histonas , Humanos , MicroRNAs/genética , Proteínas Nucleares/genética , Prognóstico , Reprodutibilidade dos Testes , Fatores de Transcrição/genética , Regulação para CimaRESUMO
Elucidating the adaptive mechanisms that prevent host immune response in cancer will help predict efficacy of anti-programmed death-1 (PD1)/L1 therapies. Here, we study the cell-intrinsic response of lung cancer (LC) to interferon-γ (IFNγ), a cytokine that promotes immunoresponse and modulates programmed death-ligand 1 (PD-L1) levels. We report complete refractoriness to IFNγ in a subset of LCs as a result of JAK2 or IFNGR1 inactivation. A submaximal response affects another subset that shows constitutive low levels of IFNγ-stimulated genes (IγSGs) coupled with decreased H3K27ac (histone 3 acetylation at lysine 27) deposition and promoter hypermethylation and reduced IFN regulatory factor 1 (IRF1) recruitment to the DNA on IFNγ stimulation. Most of these are neuroendocrine small cell LCs (SCLCs) with oncogenic MYC/MYCL1/MYCN. The oncogenic activation of MYC in SCLC cells downregulates JAK2 and impairs IγSGs stimulation by IFNγ. MYC amplification tends to associate with a worse response to anti-PD1/L1 therapies. Hence alterations affecting the JAK/STAT pathway and MYC activation prevent stimulation by IFNγ and may predict anti-PD1/L1 efficacy in LC.
Assuntos
Interferon gama , Neoplasias Pulmonares , Humanos , Interferon gama/genética , Transdução de Sinais/genética , Antígeno B7-H1/genética , Janus Quinases/metabolismo , Fatores de Transcrição STAT/metabolismo , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismoRESUMO
BACKGROUND: JUNB transcription factor contributes to the formation of the ubiquitous transcriptional complex AP-1 involved in the control of many physiological and disease-associated functions. The roles of JUNB in the control of cell division and tumorigenic processes are acknowledged but still unclear. RESULTS: Here, we report the results of combined transcriptomic, genomic, and functional studies showing that JUNB promotes cell cycle progression via induction of cyclin E1 and repression of transforming growth factor (TGF)-ß2 genes. We also show that high levels of JUNB switch the response of TGF-ß2 stimulation from an antiproliferative to a pro-invasive one, induce endogenous TGF-ß2 production by promoting TGF-ß2 mRNA translation, and enhance tumor growth and metastasis in mice. Moreover, tumor genomic data indicate that JUNB amplification associates with poor prognosis in breast and ovarian cancer patients. CONCLUSIONS: Our results reveal novel functions for JUNB in cell proliferation and tumor aggressiveness through regulation of cyclin E1 and TGF-ß2 expression, which might be exploited for cancer prognosis and therapy.
Assuntos
Neoplasias , Fator de Crescimento Transformador beta2 , Camundongos , Animais , Fator de Crescimento Transformador beta2/genética , Fator de Transcrição AP-1 , Divisão Celular , Pontos de Checagem do Ciclo Celular , Carcinogênese , Fatores de Transcrição/genéticaRESUMO
Despite the genetic inactivation of SMARCA4, a core component of the SWI/SNF-complex commonly found in cancer, there are no therapies that effectively target SMARCA4-deficient tumours. Here, we show that, unlike the cells with activated MYC oncogene, cells with SMARCA4 inactivation are refractory to the histone deacetylase inhibitor, SAHA, leading to the aberrant accumulation of H3K27me3. SMARCA4-mutant cells also show an impaired transactivation and significantly reduced levels of the histone demethylases KDM6A/UTX and KDM6B/JMJD3, and a strong dependency on these histone demethylases, so that its inhibition compromises cell viability. Administering the KDM6 inhibitor GSK-J4 to mice orthotopically implanted with SMARCA4-mutant lung cancer cells or primary small cell carcinoma of the ovary, hypercalcaemic type (SCCOHT), had strong anti-tumour effects. In this work we highlight the vulnerability of KDM6 inhibitors as a characteristic that could be exploited for treating SMARCA4-mutant cancer patients.
Assuntos
Antineoplásicos/uso terapêutico , DNA Helicases/deficiência , Histona Desmetilases/antagonistas & inibidores , Histona Desmetilases com o Domínio Jumonji/antagonistas & inibidores , Neoplasias/tratamento farmacológico , Proteínas Nucleares/deficiência , Fatores de Transcrição/deficiência , Animais , Antineoplásicos/farmacologia , Benzazepinas/farmacologia , Benzazepinas/uso terapêutico , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , DNA Helicases/metabolismo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Expressão Gênica , Inibidores de Histona Desacetilases/farmacologia , Inibidores de Histona Desacetilases/uso terapêutico , Histona Desmetilases/genética , Histona Desmetilases/metabolismo , Histonas/metabolismo , Humanos , Histona Desmetilases com o Domínio Jumonji/genética , Histona Desmetilases com o Domínio Jumonji/metabolismo , Camundongos , Neoplasias/metabolismo , Proteínas Nucleares/metabolismo , Pirimidinas/farmacologia , Pirimidinas/uso terapêutico , Fatores de Transcrição/metabolismo , Ativação TranscricionalRESUMO
Mammalian SWI/SNF (SWitch/Sucrose Non-Fermentable) complexes are ATP-dependent chromatin remodelers whose subunits have emerged among the most frequently mutated genes in cancer. Studying SWI/SNF function in cancer cell line models has unveiled vulnerabilities in SWI/SNF-mutant tumors that can lead to the discovery of new therapeutic drugs. However, choosing an appropriate cancer cell line model for SWI/SNF functional studies can be challenging because SWI/SNF subunits are frequently altered in cancer by various mechanisms, including genetic alterations and post-transcriptional mechanisms. In this work, we combined genomic, transcriptomic, and proteomic approaches to study the mutational status and the expression levels of the SWI/SNF subunits in a panel of 38 lung adenocarcinoma (LUAD) cell lines. We found that the SWI/SNF complex was mutated in more than 76% of our LUAD cell lines and there was a high variability in the expression of the different SWI/SNF subunits. These results underline the importance of the SWI/SNF complex as a tumor suppressor in LUAD and the difficulties in defining altered and unaltered cell models for the SWI/SNF complex. These findings will assist researchers in choosing the most suitable cellular models for their studies of SWI/SNF to bring all of its potential to the development of novel therapeutic applications.
RESUMO
Components of the SWI/SNF chromatin-remodeling complex, such as INI1, are inactivated in human cancer and, thus, act as tumor suppressors. Here we screened for mutations the entire coding sequence of BRG1 (SMARCA4), which encodes the ATPase of the complex, in 59 lung cancer cell lines of the most common histopathological types. Mutations were detected in 24% of the cancer cell lines, many of them in cells commonly used for lung cancer research. All mutations were homozygous and most predicted truncated proteins. The alterations were significantly more frequent in the non-small-cell lung cancer (NSCLC) type (13/37, 35%) as compared to the small-cell lung cancer (SCLC) type (1/19, 5%) (P<0.05; Fisher's Exact test) and BRG1 was the fourth most frequently altered gene in NSCLC cell lines. BRG1 mutations coexisted with mutations/deletions at KRAS, LKB1, NRAS, P16, and P53. However, alterations at BRG1 always occurred in the absence of MYC amplification, suggesting a common role in lung cancer development. In conclusion, our data strongly support that BRG1 is a bona fide tumor suppressor and a major factor in lung tumorigenesis.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/genética , DNA Helicases/genética , Inativação Gênica , Neoplasias Pulmonares/genética , Mutação , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Sequência de Bases , Linhagem Celular Tumoral , Primers do DNA , Genes myc , HumanosRESUMO
Purpose: The blockade of immune checkpoints such as PD-L1 and PD-1 is being exploited therapeutically in several types of malignancies. Here, we aimed to understand the contribution of the genetics of lung cancer to the ability of tumor cells to escape immunosurveillance checkpoints.Experimental Design: More than 150 primary non-small cell lung cancers, including pulmonary sarcomatoid carcinomas, were tested for levels of the HLA-I complex, PD-L1, tumor-infiltrating CD8+ lymphocytes, and alterations in main lung cancer genes. Correlations were validated in cancer cell lines using appropriate treatments to activate or inhibit selected pathways. We also performed RNA sequencing to assess changes in gene expression after these treatments.Results:MET-oncogenic activation tended to associate with positive PD-L1 immunostaining, whereas STK11 mutations were correlated with negative immunostaining. In MET-altered cancer cells, MET triggered a transcriptional increase of PD-L1 that was independent of the IFNγ-mediated JAK/STAT pathway. The activation of MET also upregulated other immunosuppressive genes (PDCD1LG2 and SOCS1) and transcripts involved in angiogenesis (VEGFA and NRP1) and in cell proliferation. We also report recurrent inactivating mutations in JAK2 that co-occur with alterations in MET and STK11, which prevented the induction of immunoresponse-related genes following treatment with IFNγ.Conclusions: We show that MET activation promotes the expression of several negative checkpoint regulators of the immunoresponse, including PD-L1. In addition, we report inactivation of JAK2 in lung cancer cells that prevented the response to IFNγ. These alterations are likely to facilitate tumor growth by enabling immune tolerance and may affect the response to immune checkpoint inhibitors. Clin Cancer Res; 24(18); 4579-87. ©2018 AACR.
Assuntos
Antígeno B7-H1/genética , Janus Quinase 2/genética , Neoplasias Pulmonares/tratamento farmacológico , Proteínas Proto-Oncogênicas c-met/genética , Quinases Proteína-Quinases Ativadas por AMP , Adulto , Idoso , Idoso de 80 Anos ou mais , Antígeno B7-H1/antagonistas & inibidores , Linfócitos T CD8-Positivos/imunologia , Proliferação de Células/efeitos dos fármacos , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Interferon gama/genética , Interferon gama/farmacologia , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/imunologia , Neoplasias Pulmonares/patologia , Linfócitos do Interstício Tumoral/metabolismo , Linfócitos do Interstício Tumoral/patologia , Masculino , Pessoa de Meia-Idade , Mutação , Neuropilina-1/genética , Proteína 2 Ligante de Morte Celular Programada 1 , Proteínas Serina-Treonina Quinases/genética , Análise de Sequência de RNA , Proteína 1 Supressora da Sinalização de Citocina/genética , Fator A de Crescimento do Endotélio VascularRESUMO
Our knowledge of small cell lung cancer (SCLC) genetics is still very limited, amplification of L-MYC, N-MYC, and C-MYC being some of the well-established gene alterations. Here, we report our discovery of tumor-specific inactivation of the MYC-associated factor X gene, MAX, in SCLC. MAX inactivation is mutually exclusive with alterations of MYC and BRG1, the latter coding for an ATPase of the switch/sucrose nonfermentable (SWI/SNF) complex. We demonstrate that BRG1 regulates the expression of MAX through direct recruitment to the MAX promoter, and that depletion of BRG1 strongly hinders cell growth, specifically in MAX-deficient cells, heralding a synthetic lethal interaction. Furthermore, MAX requires BRG1 to activate neuroendocrine transcriptional programs and to upregulate MYC targets, such as glycolysis-related genes. Finally, inactivation of the MAX dimerization protein, MGA, was also observed in both non-small cell lung cancer and SCLC. Our results provide evidence that an aberrant SWI/SNF-MYC network is essential for lung cancer development.
Assuntos
Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Carcinoma Pulmonar de Células não Pequenas/genética , DNA Helicases/metabolismo , Neoplasias Pulmonares/genética , Proteínas Nucleares/metabolismo , Carcinoma de Pequenas Células do Pulmão/genética , Fatores de Transcrição/metabolismo , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Proliferação de Células , DNA Helicases/genética , Regulação Neoplásica da Expressão Gênica , Genes myc , Humanos , Neoplasias Pulmonares/patologia , Mutação , Proteínas Nucleares/genética , Regiões Promotoras Genéticas , Carcinoma de Pequenas Células do Pulmão/patologia , Fatores de Transcrição/genéticaRESUMO
Cancer evolution is a process that is still poorly understood because of the lack of versatile in vivo longitudinal studies. By generating murine non-small cell lung cancer (NSCLC) orthoallobanks and paired primary cell lines, we provide a detailed description of an in vivo, time-dependent cancer malignization process. We identify the acquisition of metastatic dissemination potential, the selection of co-driver mutations, and the appearance of naturally occurring intratumor heterogeneity, thus recapitulating the stochastic nature of human cancer development. This approach combines the robustness of genetically engineered cancer models with the flexibility of allograft methodology. We have applied this tool for the preclinical evaluation of therapeutic approaches. This system can be implemented to improve the design of future treatments for patients with NSCLC.
Assuntos
Evolução Biológica , Carcinoma Pulmonar de Células não Pequenas/genética , Neoplasias Pulmonares/genética , Neoplasias Experimentais/genética , Aloenxertos/efeitos dos fármacos , Aloenxertos/patologia , Animais , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Modelos Animais de Doenças , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/patologia , Camundongos , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/patologiaRESUMO
BRG1, a member of the SWI/SNF complex, is mutated in cancer, but it is unclear how it promotes tumourigenesis. We report that re-expression of BRG1 in lung cancer cells up-regulates lung-specific transcripts, restoring the gene expression signature of normal lung. Using cell lines from several cancer types we found that those lacking BRG1 do not respond to retinoic acid (RA) or glucocorticoids (GC), while restoration of BRG1 restores sensitivity. Conversely, in SH-SY5Y cells, a paradigm of RA-dependent differentiation, abrogation of BRG1 prevented the response to RA. Further, our data suggest an antagonistic functional connection between BRG1 and MYC, whereby, refractoriness to RA and GC by BRG1 inactivation involves deregulation of MYC activity. Mechanistically, some of these effects are mediated by BRG1 binding to MYC and MYC-target promoters. The BRG1-MYC antagonism was also evident in primary tumours. Finally, BRG1 restoration significantly dampened invasion and progression and decreased MYC in lung cancer cells orthotopically implanted in nude mice. Thus, BRG1 inactivation enables cancer cells to sustain undifferentiated gene expression programs and prevent its response to environmental stimuli.