RESUMO
The oncofetal H19 gene transcribes a long non-coding RNA(lncRNA) that is essential for tumor growth. Here we found that numerous established inducers of epithelial to mesenchymal transition(EMT) also induced H19/miR-675 expression. Both TGF-ß and hypoxia concomitantly induced H19 and miR-675 with the induction of EMT markers. We identified the PI3K/AKT pathway mediating the inductions of Slug, H19 RNA and miR-675 in response to TGF-ß treatment, while Slug induction depended on H19 RNA. In the EMT induced multidrug resistance model, H19 level was also induced. In a mouse breast cancer model, H19 expression was tightly correlated with metastatic potential. In patients, we detected high H19 expression in all common metastatic sites tested, regardless of tumor primary origin. H19 RNA suppressed the expression of E-cadherin protein. H19 up-regulated Slug expression concomitant with the suppression of E-cadherin protein through a mechanism that involved miR-675. Slug also up-regulated H19 expression and activated its promoter. Altogether, these results may support the existence of a positive feedback loop between Slug and H19/miR-675, that regulates E-cadherin expression. H19 RNA enhanced the invasive potential of cancer cells in vitro and enhanced tumor metastasis in vivo. Additionally, H19 knockdown attenuated the scattering and tumorigenic effects of HGF/SF. Our results present novel mechanistic insights into a critical role for H19 RNA in tumor progression and indicate a previously unknown link between H19/miR-675, Slug and E-cadherin in the regulation of cancer cell EMT programs.
Assuntos
Neoplasias da Mama/genética , Transição Epitelial-Mesenquimal/genética , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , RNA Longo não Codificante/genética , Fatores de Transcrição/genética , Animais , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Caderinas/genética , Caderinas/metabolismo , Hipóxia Celular , Linhagem Celular Tumoral , Resistência a Múltiplos Medicamentos , Resistencia a Medicamentos Antineoplásicos/genética , Retroalimentação Fisiológica , Feminino , Humanos , Glândulas Mamárias Animais/metabolismo , Glândulas Mamárias Animais/patologia , Neoplasias Mamárias Experimentais/genética , Neoplasias Mamárias Experimentais/metabolismo , Neoplasias Mamárias Experimentais/patologia , Camundongos , MicroRNAs/metabolismo , Metástase Neoplásica , Oxigênio/metabolismo , Oxigênio/farmacologia , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Longo não Codificante/metabolismo , Transdução de Sinais , Fatores de Transcrição da Família Snail , Fatores de Transcrição/metabolismo , Fator de Crescimento Transformador beta/farmacologiaRESUMO
The imprinted oncofetal long non-coding RNA (lncRNA) H19 is expressed in the embryo, down-regulated at birth and then reappears in tumors. Its role in tumor initiation and progression has long been a subject of controversy, although accumulating data suggest that H19 is one of the major genes in cancer. It is actively involved in all stages of tumorigenesis and is expressed in almost every human cancer. In this review we delineate the various functions of H19 during the different stages in the complex process of tumor progression. H19 up-regulation allows cells to enter a "selfish" survival mode in response to stress conditions, such as destabilization of the genome and hypoxia, by accelerating their proliferation rate and increasing overall cellular resistance to stress. This response is tightly correlated with nullification, dysfunction or significant down-regulation of the master tumor suppressor gene P53. The growing evidence of H19's involvement in both proliferation and differentiation processes, together with its involvement in epithelial to mesenchymal transition (EMT) and also mesenchymal to epithelial transition (MET), has led us to conclude that some of the recent disputes and discrepancies arising from current research findings can be resolved from a viewpoint supporting the oncogenic properties of H19. According to a holistic approach, the versatile, seemingly contradictory functions of H19 are essential to, and differentially harnessed by, the tumor cell depending on its context within the process of tumor progression.
Assuntos
RNA Longo não Codificante/genética , Animais , Progressão da Doença , Transição Epitelial-Mesenquimal/genética , Transição Epitelial-Mesenquimal/fisiologia , Regulação Neoplásica da Expressão Gênica/genética , Regulação Neoplásica da Expressão Gênica/fisiologia , Instabilidade Genômica/genética , Humanos , RNA Longo não Codificante/fisiologiaRESUMO
Since it was first described, the imprinted cluster 11p15.5 has been reported to be deregulated in a variety of pediatric and adult cancers including that of the lung. Both protein coding and non-coding genes functioning as oncogenes or as tumor suppressor genes reside within this cluster. Oncomirs that can function as oncogenes or as tumor suppressors have also been reported. While a complete account of the role played by the 11p15.5 imprinted cluster in lung cancer is beyond the scope of this review, we will focus on the role of the non-coding RNAs processed from the H19-IGF2 loci. A special emphasis will be given to the H19/miR-675 gene locus. Their potential diagnostic and therapeutic use in lung cancer will be described.
Assuntos
Loci Gênicos , Impressão Genômica , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/terapia , RNA Longo não Codificante/genética , Animais , Carcinogênese/patologia , Humanos , Neoplasias Pulmonares/diagnóstico , MicroRNAs/metabolismo , RNA Longo não Codificante/metabolismoRESUMO
Expression of the imprinted H19 gene is remarkably elevated in a large number of human cancers. Recently, we reported that H19 RNA is up-regulated in hypoxic stress and furthermore, it possesses oncogenic properties. However, the underlying mechanism(s) of these phenomena remain(s) unknown. Here we demonstrate a tight correlation between H19 RNA elevation by hypoxia and the status of the p53 tumor suppressor. Wild type p53 (p53(wt)) prevents the induction of H19 upon hypoxia, and upon its reconstitution in p53(null) cells. The last case is accompanied by a decrease in cell viability. The p53 effect is nuclear and seems independent of its tetramerization. Furthermore, using knockdown and over-expression approaches we identified HIF1-alpha as a critical factor that is responsible for H19 induction upon hypoxia. Knocking down HIF1-alpha abolishes H19 RNA induction, while its over-expression significantly enhances the H19 elevation in p53(null) hypoxic cells. In p53(wt) hypoxic cells simultaneous suppression of p53 and over-expression of HIF1-alpha are needed to induce H19 significantly, while each treatment separately resulting in a mild induction, indicating that the molecular mechanism of p53 suppression effect on H19 may at least in part involve interfering with HIF1-alpha activity. In vivo a significant increase in H19 expression occurred in tumors derived from p53(null) cells but not in p53(wt) cells. Taken together, our results indicate that a functional link exists between p53, HIF1-alpha and H19 that determines H19 elevation in hypoxic cancer cells. We suggest that this linkage plays a role in tumor development.
Assuntos
Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Hipóxia/metabolismo , Neoplasias/metabolismo , RNA não Traduzido/genética , Proteína Supressora de Tumor p53/fisiologia , Animais , Western Blotting , Linhagem Celular Tumoral , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Humanos , Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/antagonistas & inibidores , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Camundongos , Camundongos Nus , Neoplasias/genética , Neoplasias/patologia , RNA Longo não Codificante , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/farmacologia , RNA não Traduzido/antagonistas & inibidores , RNA não Traduzido/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
To date, classical deterministic Newtonian physics has been used by biologists to describe living processes. However, it is increasingly appreciated that the probabilistic view offered by quantum mechanics more accurately describes the behavior of atoms and materials in all systems. Here, we discuss how the concepts of quantum mechanics can be applied to biological processes involved in cancer. We present a concise summary inspired by Heisenberg's Uncertainty Principle to describe our «Genetic Environmental Field Hypothesis¼. Combining the uncertainties of genetic changes as expressed by epigenetic changes and/or somatic mutations with the uncertainties of environmental changes, cells may become cancerous as a way to increase entropy. Throughout the paper we will utilize the H19 gene system as an example. Using the concepts of quantum mechanics to describe oncological processes may provide novel directions in our understanding of cancer.
Assuntos
Neoplasias , Teoria Quântica , Entropia , IncertezaRESUMO
Long non-coding RNA (lncRNA) genes are emerging as key players in the metastatic cascade. Current evidence indicate that H19 lncRNA and the microRNA(miRNA) miR-675, which is processed from it, play crucial roles in metastasis, through the regulation of critical events specifically the epithelial to mesenchymal (EMT) and the mesenchymal to epithelial transitions (MET). This review summarizes recent mechanistic pathways and tries to put together seemingly conflicting data from different reports under one proposed general scheme underlying the various roles of H19/miR-675 in the metastatic cascade. We propose several approaches to harnessing this knowledge for translational medicine.
Assuntos
Transição Epitelial-Mesenquimal , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , Neoplasias/genética , Neoplasias/patologia , RNA Longo não Codificante/genética , Humanos , Metástase NeoplásicaRESUMO
BACKGROUND: The H19-IGF2 locus is either highly expressed and/or shows aberrant allelic pattern of expression in a large array of human cancers, while rarely expressed in the corresponding normal tissue. Preclinical, clinical studies and human compassionate using a DNA plasmid containing H19 and/or IGF2-P4 regulatory sequences that drive the expression of an intracellular toxin [diphtheria toxin A-fragment (DTA)] have demonstrated promising results in several types of carcinomas. Recently we reported that a single construct that expresses DTA under the control of both H19 and IGF2 P4 promoters showed superior efficacy in vitro as well as in vivo, in comparison to a single promoter construct in bladder carcinoma. Here we extended this approach to glioblastoma and tested the antitumor efficacy of the double promoter DTA-expressing vector (H19-DTA-P4-DTA) in vitro as well as in heterotopic animal model. H19 gene expression was tested by in-situ hybridization (ISH) and by quantitative Real-Time PCR (qRT-PCR) in samples of diffuse glioma. METHODS: IGF2-P4 gene expression was tested by qRT-PCR as well. RESULTS: Both H19 and IGF2-P4 transcripts were highly expressed in high grade gliomas. Furthermore, significant H19 expression in other types of primary brain tumors as well as in brain metastases was detected by ISH. Both A172 and U87 human glioblastoma cell lines showed high expression of IGF2-P4 while the A172 cell line showed high expression of H19 RNA as well. H19-DTA-P4-DTA exhibited superior cytotoxic activity compared to the single promoter expression vectors, in U87 and A172 glioblastoma cell lines in vitro and showed antitumoral efficacy in heterotopic glioblastoma animal model. CONCLUSIONS: Our findings indicate antitumoral efficacy against glioblastoma of the targeted double promoter vector H19-DTA-P4-DTA, both in-vitro and in-vivo. Thus, its test in orthotopic animal model of glioblastoma as well as in clinical trials is warranted.
RESUMO
BACKGROUND: The highly upregulated in liver cancer (HULC) gene transcribes to an mRNA-like noncoding RNA (ncRNA) by the RNA polymerase II and processed by capping, splicing and polyadenylation. It is specifically expressed in the hepatocytes with striking upregulation in hepatocellular carcinoma (HCC). OBJECTIVES: To study the expression levels of HULC in normal colorectal samples, primary colorectal carcinomas and in secondary tumors formed from colorectal carcinomas that metastasize to either the liver or the lymph nodes, taken from the same patients. Also a panel of carcinoma cell lines is tested for HULC expression. BASIC METHODS: Semiquantitative reverse transcriptase-PCR technique is used to detect for HULC expression in study specimens and cell lines. RESULTS: Consistent with the previous report, HULC is neither expressed in primary colorectal carcinomas samples nor in their normal counterparts. We show for the first time those colorectal carcinomas that metastasize to the livers but not to lymph nodes experience an upregulation of HULC ncRNA in all the samples tested (n= 8), with a strong-to-moderate expression in six out of eight. Moreover HULC is not expressed in the majority of carcinoma cell lines tested and also in samples of normal bladder and bladder cancers of various grades. We also show that HULC ncRNA is upregulated in two hepatocellular carcinoma cell lines producing HBV relevant to their parental lines that do not produce HBV. CONCLUSION: Our results presented here indicate that HULC expression is not confined to HCC, but also to those colorectal carcinomas that metastasize to the liver.
Assuntos
Neoplasias Colorretais/genética , Neoplasias Hepáticas/genética , RNA Neoplásico/genética , RNA não Traduzido/genética , Regulação para Cima , Animais , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias Hepáticas/secundário , Camundongos , Camundongos Nus , Transplante de Neoplasias , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Transplante Heterólogo , Células Tumorais CultivadasRESUMO
BACKGROUND: Mutations and epigenetic aberrant signaling of growth factors pathways contribute to carcinogenesis. Recent studies reveal that non-coding RNAs are controllers of gene expression. H19 is an imprinted gene that demonstrates maternal monoallelic expression without a protein product; although its expression is shut off in most tissues postnatally, it is re-activated during adult tissue regeneration and tumorigenesis. Moreover, H19 is highly expressed in liver metastasis derived from a range of carcinomas. The objective of this study is to explore the role of H19 in carcinogenesis, and to determine its identification as an anti-tumor target. METHODOLOGY/PRINCIPLE FINDINGS: By controlling oxygen pressure during tumor cell growth and H19 expression levels, we investigated the role of H19 expression in vitro and in vivo in hepatocellular (HCC) and bladder carcinoma. Hypoxia upregulates the level of H19 RNA. Ablations of tumorigenicity of HCC and bladder carcinomas in vivo are seen by H19 knockdown which also significantly abrogates anchorage-independent growth after hypoxia recovery, while ectopic H19 expression enhances tumorigenic potential of carcinoma cells in vivo. Knocking-down H19 message in hypoxic stress severely diminishes p57(kip2) induction. We identified a number of potential downstream targets of H19 RNA, including angiogenin and FGF18. CONCLUSIONS: H19 RNA harbors pro-tumorigenic properties, thus the H19 gene behaves as an oncogene and may serve as a potential new target for anti-tumor therapy.