Reduced expression of H19 in bone marrow cells from chronic myeloproliferative disorders.
Explore the source record for details and available documents.
Bone Marrow Cells↗
SEARCH · PubMed Health
Results for “Long noncoding RNA”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Disruption of imprinted genes at chromosome region 11p15.5 in paediatric rhabdomyosarcoma.
Rhabdomyosarcomas are characterized by loss of heterozygosity (LOH) at chromosome region 11p15.5, a region known to contain several imprinted genes including insulin-like growth factor 2 (IGF2), H19, and p57(KIP2). We analyzed 48 primary tumour samples and found distinct genetic changes at 11p15.5 in alveolar and embryonal histological subtypes. LOH was a feature of embryonal tumours, but at a lower frequency than previous studies. Loss of imprinting (LOI) of the IGF2 gene was detected in 6 of 13 informative cases, all harbouring PAX3-FKHR or PAX7-FKHR fusion genes characteristic of alveolar histology. In contrast, H19 imprinting was maintained in 14 of 15 informative cases and the case with H19 LOI had maintenance of the IGF2 imprint indicating separate mechanisms controlling imprinting of IGF2 and H19. The adult promoter of IGF2, P1, was used in 5 of 14 tumours and its expression was unrelated to IGF2 imprinting status implying a further mechanism of altered IGF2 regulation. The putative tumour suppressor gene p57(KIP2) was expressed in 15 of 29 tumours and expression was unrelated to allele status. Moreover, in tumours with p57(KIP2) expression, there was no evidence for inactivating mutations, suggesting that p57(KIP2) is not a tumour suppressor in rhabdomyosarcoma.
Adult↗
Gender-specific gene expression in post-mortem human brain: localization to sex chromosomes.
Gender differences in brain development and in the prevalence of neuropsychiatric disorders such as depression have been reported. Gender differences in human brain might be related to patterns of gene expression. Microarray technology is one useful method for investigation of gene expression in brain. We investigated gene expression, cell types, and regional expression patterns of differentially expressed sex chromosome genes in brain. We profiled gene expression in male and female dorsolateral prefrontal cortex, anterior cingulate cortex, and cerebellum using the Affymetrix oligonucleotide microarray platform. Differentially expressed genes between males and females on the Y chromosome (DBY, SMCY, UTY, RPS4Y, and USP9Y) and X chromosome (XIST) were confirmed using real-time PCR measurements. In situ hybridization confirmed the differential expression of gender-specific genes and neuronal expression of XIST, RPS4Y, SMCY, and UTY in three brain regions examined. The XIST gene, which silences gene expression on regions of the X chromosome, is expressed in a subset of neurons. Since a subset of neurons express gender-specific genes, neural subpopulations may exhibit a subtle sexual dimorphism at the level of differences in gene regulation and function. The distinctive pattern of neuronal expression of XIST, RPS4Y, SMCY, and UTY and other sex chromosome genes in neuronal subpopulations may possibly contribute to gender differences in prevalence noted for some neuropsychiatric disorders. Studies of the protein expression of these sex-chromosome-linked genes in brain tissue are required to address the functional consequences of the observed gene expression differences.
Actins↗
Unique expression patterns of H19 in human testicular cancers of different etiology.
The expression pattern of the imprinted human H19 gene was investigated in testicular cancers of different etiology, as well as in normal testicular parenchyma, parenchyma without germ cells, and adjacent to testicular germ cell tumors of adolescents and adults (TGCTs), using RNase protection analysis, mRNA in situ hybridization and reverse-transcription polymerase chain reaction. While different total expression levels were detected in spermatocytic seminomas, lymphomas, a Sertoli cell tumor and Leydig cell tumors, none showed a disturbance of monoallelic expression. Strikingly, the majority of invasive TGCTs revealed expression of both parental alleles. The total level of expression highly correlated with differentiation lineage and stage of maturation, similar to that as reported during early normal embryogenesis. Biallelic expression could also be determined specifically in testis parenchyma containing the preinvasive lesion of this cancer. We therefore conclude that within the adult testis, biallelic H19 expression is specific for TGCTs, and that the level of expression is dependent on differentiation lineage and maturation stage. This is in agreement with the proposed primordial germ cell-origin of this cancer, and might be related to retention of embryonic characteristics in TGCTs. In addition, our data argue against H19 being a tumor suppressor gene.
Adolescent↗
Expression and parental imprinting of the H19 gene in human rhabdomyosarcoma.
The expression of Insulin-like Growth Factor 2 (IGF-2) and H19, two genes located on human chromosome 11p15 and provided with cell growth modulating activity, is regulated by parental imprinting, in that the activity of their alleles is dependent on the parental origin. Parental bias in the genetic alterations of chromosome 11p15 observed in several pediatric cancers suggests the involvement of imprinted genes in tumor development. We have previously reported that the number of functional IGF-2 alleles is frequently increased in rhabdomyosarcoma (RMS), as a consequence of either relaxation of imprinting (LOI) or gene duplication. Here we show that the expression of the H19 gene is significantly suppressed with respect to normal muscle tissue in 13 out of 15 rhabdomyosarcomas with embryonal histology (ERMS) and in three out of 11 rhabdomyosarcomas classified as alveolar subtype (ARMS). Since a growth-inhibitory activity has been found associated with the H19 gene, the extinction of its expression can contribute to RMS development. Parental imprinting of the H19 gene was found conserved in all informative RMSs, including those whose ICF-2 imprinting was relaxed, indicating that LOI is a gene-specific event. Seven ERMSs and one ARMS displaying low H19 RNA levels showed an underrepresentation of the expressed allele in their genotype. This result is consistent with the paternal imprinting of the H19 gene and with the preferential loss of the maternal 11p15 alleles in these neoplasms. Low H19 expression was also found in four out of eight RMSs retaining the heterozygosity at 11p15, but showing IGF-2 LOI. These findings suggest that the genetic and epigenetic alterations affecting chromosome 11p15 in a high number of RMSs cause deregulation of more than one imprinted gene, possibly affecting tumor growth, including the extinction of H19 expression and an increase in the number of active IGF-2 alleles.
Alleles↗
The expression of the imprinted genes H19 and IGF-2 in choriocarcinoma cell lines. Is H19 a tumor suppressor gene?
H19 is a paternally imprinted gene with unknown function. It is located in close proximity to the maternally imprinted IGF-2 gene on chromosome 11p15.5. In this study no consistent relationship between the expression of these two genes in clones derived from JEG-3 and JAr cell lines could be detected. Nor could a consistent relationship be detected between the expression levels of these two genes and between certain characteristic tumorigenic properties of these clones. We included in this study clones, expressing low H19 levels, which after transfection with an H19 expression construct highly expressed the H19 gene. In tumors, formed by the injection of cells of JAr or JEG-3 clones into nude mice, the H19 expression was high and irrelevant to the expression level in the cells before the injection. The same phenomenon was found for IGF-2 expression during tumorigenesis caused by cells of different JEG-3 clones and in some but not all JAr derived clones. Both H19 and IGF-2 are biallelicly expressed in all the JAr and JEG-3 clones. In summary, our observations point to the conclusion that H19 is not a tumor suppressor gene. However, its high expression in all the tumors formed after injection of cells of the JAr and JEG-3 clones, leaves its role, if any, in choriocarcinogenesis an open question.
Animals↗
Hypervariable allelic expression patterns of the imprinted IGF2 gene in tumor cells.
The IGF2 gene, which encodes a growth factor, is subject to genomic imprinting. The frequently observed loss of IGF2 imprinting in a variety of tumors has been suggested to contribute to neoplasia. Since these reports have not documented the imprinting status of IGF2 at the cellular level, it cannot be excluded that the imprinting status might vary within the tumor. The possibility that loss of IGF2 imprinting in neoplastic cells reflects random imprinting patterns, was therefore addressed. We show here that individual cell populations of the JEG-3 choriocarcinoma cell line display heterogenous imprinting patterns of both IGF2 and H19. In addition, a lack of correlation between IGF2 and H19 imprinting status suggests that any regional parental imprint has been functionally lost. This notion is reinforced by the observation that JEG-3 cell subclones display a range of promoter-specific IGF2 allele usage. Moreover, we observed that the imprinting status of H19 and IGF2 were differentially modulated in JEG-3-derived tumors generated in nude mice. The results suggest that allele-specific expression of IGF2 operates in the absence of a parental imprint. Finally, our observations urge caution with respect to the general interpretation of biallelic expression as 'loss of imprinting'.
Alleles↗
The H19 TATA-less promoter is efficiently repressed by wild-type tumor suppressor gene product p53.
The developmentally regulated H19 gene displays several remarkable properties: expression of an apparently non-translated mRNA, genomic imprinting (maternal allele only expressed), relaxation of the imprinting and/or epigenetic lesions demonstrated in some tumors. Despite several observations after relaxation of imprinting status of the gene, data on trans and cis-acting factors required for the human H19 gene expression are still missing. As a first approach to address identification of factors involved in the regulation of the gene, we found that cells from a p53 antisense-transfected HeLa clone displayed increased amounts of H19 transcripts when compared to the non-transfected cells. Moreover, a HeLa clone stably transfected with a temperature sensitive (ts) 143 Ala p53 mutant exhibited temperature-dependent regulation of H19 expression. This preliminary indication of the repressing effect of the p53 protein on H19 expression has been confirmed by transient cotransfection experiments in HeLa cells, using luciferase surrogate constructs under the control of the 823 bp sequence immediately upstream of the transcription start point of the H19 gene, and different constructs containing sense, antisense or a ts 143 Ala mutant p53 cDNA. We observed an increase of H19 promoter-driven activity in transient cotransfections with the antisense p53 cDNA and the temperature sensitive mutant p53 at the non-permissive temperature, but a decrease with sense wild-type p53 cDNA. Furthermore, the cotransfection experiments were repeated in a cell line lacking endogenous p53. (Calu 6 cells) and the results provided additional evidence for a down regulation of the expression of the H19 gene by the p53 protein.
Gene Expression Regulation, Neoplastic↗
Cloning and characterization of human and mouse telomerase RNA gene promoter sequences.
Variation in telomerase activity is correlated with cellular senescence and tumour progression. However, although the enzymatic activity of telomerase has been well studied, very little is known about how expression of telomerase genes is regulated in mammalian cells. We have therefore cloned the promoter regions of the human (hTR), and mouse, (terc), telomerase RNA genes in order to identify the regulatory elements controlling telomerase RNA gene transcription. 1.76 kb encompassing the hTR gene promoter region was sequenced, as was 4 kb encompassing the terc promoter. No significant sequence similarity could be detected in comparisons between human and mouse 5'-regions, flanking the transcribed sequences. However, both the human and mouse telomerase RNA genes are within CpG islands and may therefore be under the regulation of DNA methylation. Transient expression of hTR-reporter gene constructs in HeLa and GM847 cells identified the elements responsible for promoter activity are contained in a 231 bp region upstream of the transcriptional start site. Transient expression of terc-reporter gene constructs in Swiss3T3 and A9 cells identified the elements responsible for promoter activity are contained in a 73 bp region upstream of the transcriptional start site. These studies have implications for novel transcription targeted cancer therapies.
Animals↗
Expression of mouse telomerase reverse transcriptase during development, differentiation and proliferation.
We have identified the mouse telomerase reverse transcriptase component (mTERT) and demonstrate both substantial sequence homology to the human ortholog (hTERT), and the presence of reverse transcriptase and telomerase specific motifs. Furthermore, we show functional interchangeability with hTERT in in vitro telomerase reconstitution experiments, as mTERT produces strong telomerase activity in combination with the human telomerase RNA component hTR. The mouse TERT is widely expressed at low levels in adult tissues, with greatest abundance during embryogenesis and in adult thymus and intestine. The mTERT component mRNA levels were regulated during both differentiation and proliferation, while mTR levels remained constant throughout both processes. Comparison of mTERT and mTR levels to telomerase activity indicates that mTERT expression is more tightly linked to the regulation of telomerase activity during these processes than is mTR. In contrast to the situation in human cell cultures, mTERT transcript levels are present at readily detectable levels in primary cultured cells and are not upregulated following crisis. The widespread expression of mTERT in primary cells and mouse tissues could explain the increased frequency of spontaneous immortalization of mouse cells in culture and tumorigenesis in vivo.
3T3 Cells↗
Telomerase activity during spontaneous immortalization of Li-Fraumeni syndrome skin fibroblasts.
Li-Fraumeni Syndrome (LFS) is characterized by heterozygous germline mutations in the p53 gene. Accompanied by genomic instability and loss or mutation of the remaining wild type p53 allele, a low frequency of spontaneous immortalization in LFS fibroblasts occurs. It is believed that the loss of p53 wild type function contributes to immortalization of these LFS fibroblasts, but it is not clear if this is sufficient. Because stabilization of telomere length is also thought to be a necessary step in immortalization, telomerase activity, expression of the telomerase RNA component (hTR) and telomere length were anlaysed at various passages during the spontaneous immortalization of LFS skin fibroblasts. One LFS strain which immortalized, MDAH087 (087), had no detectable telomerase activity whereas another LFS strain which immortalized, MDAH041 (041), had detectable telomerase activity. In preimmortal cells from both strains, hTR was not detected by in situ hybridization. Immortal 087 cells remained negative for hTR, while immortal 041 cells demonstrated strong hTR in situ hybridization signals. 087 cells had long and heterogenous telomeres whereas telomeres of 041 cells had short, stable telomere lengths. Tumorigenicity studies in nude mice with ras-transformed 087 and 041 cells resulted in both cell lines giving rise to tumors and retaining telomerase status. Overall these results suggest that strain specificity may be important in telomerase re-activation and that both abrogation of p53 function and a mechanism to maintain telomeres are necessary for immortalization.
Animals↗
Steroid hormones modulate H19 gene expression in both mammary gland and uterus.
H19 is an imprinted and developmentally regulated gene whose product remains apparently untranslated. In a previous study on breast adenocarcinomas, we reported that overexpression of the H19 gene was significantly correlated with the presence of steroid receptors, suggesting the putative role of hormones in H19 transcription. To determine the mode of steroid action, we have detected levels of H19 RNA synthesis during mammary gland development by in situ hybridization (ISH): two peaks of H19 transcription occur during puberty and pregnancy. Furthermore, we demonstrated by ISH that in the uterus H19 RNA synthesis is high during estrus and metestrus phases. To test steroid control of H19 transcription, ovariectomized and adrenalectomized mice were supplemented, 1 week after surgery, with 17-beta-estradiol (E2, 20 microg/kg/day), progesterone (P, 1 mg/kg/day) or corticosterone (B, 0.3 mg/ kg/day) for 2 weeks. According to ISH data, E2 and to a lesser extent B stimulated H19 transcription in the uterus, whereas P inhibited it. To confirm the in vivo results, in vitro experiments were performed using cultures of MCF-7 cells (a hormone-sensitive mammary cell line). E2 stimulated the endogenous H19 gene of this cell line and tamoxifen inhibited this effect. Furthermore, we performed transient cotransfections in MCF-7, in HBL-100 (another hormone-sensitive mammary cell line) and in BT-20 (a hormone-insensitive mammary cell line) with various constructs of ERalpha (WT or mutated) and PR-A, in presence or absence of steroid hormones. We demonstrated that ERalpha up-regulated the H19 promoter in MCF-7 and in HBL-100, whereas PR-A did not have any effect per se. Moreover, in MCF-7, PR-A antagonized clearly the ERalpha-mediated promoter enhancement, but in HBL-100 this counteracting effect on the ERalpha up-regulation was not found. Interestingly, the same experiments performed in BT-20 cell line provided very similar results as those obtained in MCF-7 cells, with a clear down-regulation mediated by PR-A on the H19 promoter. All these in vitro data are in agreement with in vivo results. In addition, data obtained with ERalpha mutants indicate that H19 promoter activation is both ligand-dependent and ligand-independent. We have thus demonstrated that H19 gene expression is controlled by steroid hormones; furthermore, this gene is highly expressed in hormone-sensitive organs when the hormonal stimulation is accompanied with a morphological repair.
Adrenalectomy↗
Frequent loss of imprinting at the IGF2 and H19 genes in head and neck squamous carcinoma.
Genomic imprinting is an inherited epigenetic phenomenon that results in parental-origin-specific gene expression in somatic cells. Relaxation or loss of this feature in certain genes has been demonstrated in several pediatric and adult neoplasms, suggesting an association with tumorigenesis. We analysed 64 primary untreated head and neck squamous carcinoma for the loss of imprinting in the IGF2 and H19 genes to determine the implications of this alteration in the development and progression of these tumors. Forty-nine (77%) of the 64 tumors were informative for imprinting analyses of these genes. IGF2 and H19 were imprinted in all normal squamous epithelium examined. Twelve (37.5%) of 32 tumors informative for H19 and 11 (40.7%) of 27 tumors informative for IGF2 manifested loss of imprinting. Ten tumors were informative for both genes, of which four maintained the constitutional imprinting and six showed loss of imprinting at either H19 or IGF2. These data suggest that loss of imprinting at the IGF2 and H19 loci play a role in the oncogenesis of head and neck carcinoma.
Adult↗
Treatment of prostate cancer in vitro and in vivo with 2-5A-anti-telomerase RNA component.
Prostate cancer is the most common malignancy of elderly men in the United States. Since there is no curative treatment for advanced prostate cancer, exploration of novel modalities of treatment is essential. Telomerase, a ribonucleoprotein, is detected in the vast majority of prostate cancer, but not in normal or benign prostatic hyperplasia tissues. Thus, telomerase is expected to be a very strong candidate for targeted therapy of prostate cancer. In this study, we synthesized a 19-mer antisense oligonucleotide against the RNA component of human telomerase (hTR) linked to a 2-5A molecule (2-5A-anti-hTR) and examined its cytotoxic effect on prostate cancer cells. The 2-5A antisense strategy relies on the recruitment and activation of RNase L at the site of targeted RNA sequence. We here show that treatment with 2-5A-anti-hTR in the presence of a cationic liposome reduced cell viability of tumor cell lines tested to 9-18% within 6 days. In contrast, normal fibroblast cells were resistant to the treatment. Its effect was mainly due to induction of apoptosis by activated caspase family members. Furthermore, treatment of subcutaneous tumors in nude mice with 2-5A-anti-hTR significantly suppressed the tumor growth through induction of apoptosis (P<0.001). The treatment with 2-5A-anti-hTR may be a promising strategy for the treatment modality of prostate cancer with telomerase activity.
Animals↗
PIK3CA as an oncogene in cervical cancer.
Amplification of chromosome arm 3q is the most consistent aberration in cervical cancer, and is implicated in the progression of dysplastic uterine cervical cells into invasive cancer. The present study employed the 'positional candidate gene' strategy to determine the contribution of PIK3CA, which is located in 3q26.3, in cervical tumorigenesis. PIK3CA is known to be involved in the PI 3-kinase/AKT signaling pathway, which plays an important role in regulating cell growth and apoptosis. The results of comparative genomic hybridization show that the 3q26.3 amplification was the most consistent chromosomal aberration in primary tissues of cervical carcinoma, and a positive correlation between an increased copy number of PIK3CA (detected by competitive PCR) and 3q26.3 amplification was found in tumor tissues and in cervical cancer cell lines. In cervical cancer cell lines harboring amplified PIK3CA, the expression of gene product (p110alpha) of PIK3CA was increased, and was subsequently associated with high kinase activity. In addition, transformation phenotypes in these lines, including increased cell growth and decreased apoptosis, were found to be significantly affected by the treatment of specific PI 3-kinase inhibitor, suggesting that increased expression of PIK3CA in cervical cancer may result in promoting cell proliferation and reducing apoptosis. These evidences support that PIK3CA is an oncogene in cervical cancer and PIK3CA amplification may be linked to cervical tumorigenesis. Oncogene (2000).
Apoptosis↗
H19 gene expression is up-regulated exclusively by stabilization of the RNA during muscle cell differentiation.
H19 is a paternally imprinted gene whose expression produces a 2.4 kb RNA in most tissues during development and in mammalian myoblastic cell lines upon differentiation. Deletion of the active maternal allele of H19 and its flanking regions in the mouse leads to biallelic methylation and loss of imprinting of the neighbouring Igf2 gene. The function of H19 RNA remains unknown and, although polysome-associated, the absence of a conserved open reading frame suggests that it does not encode a protein product. We describe a novel post-transcriptional regulation of H19 gene expression which, in spite of this lack of coding capacity, is dependent on translational activity. We show that stabilization of the RNA is solely responsible for its accumulation during in vitro muscle cell differentiation. This conclusion is based on the finding that inhibition of protein synthesis results in a dramatic destabilization of H19 RNA in proliferating mouse C2C12 myoblastic cells but not in differentiated cells, and on run-on experiments which showed that the rate of transcription of H19 RNA remains constant during muscle cell differentiation. This mechanism could also be involved in H19 gene expression during mouse development in addition to its transcriptional activation which we have shown to occur.
Animals↗
The H19 endodermal enhancer is required for Igf2 activation and tumor formation in experimental liver carcinogenesis.
The expression of the linked but reciprocally imprinted Igf2 and H19 genes is activated in adult liver in the course of tumor development. By in situ hybridization analysis we have shown that both the Igf2 and H19 RNAs are expressed in the majority of the neoplastic nodules, and that hepatocellular carcinomas are developed in an experimental model of liver carcinogenesis. H19 is also highly activated in smaller and less distinct hyperplastic regions. The few neoplastic areas showing Igf2 but no H19 RNA display loss of the maternally inherited allele at the Igf2/H19 locus. These data are compatible with the existence of a common activation mechanism of these two genes during liver carcinogenesis and with a stronger H19 induction in the pre-neoplastic lesions. By using mice carrying a deletion of the H19 endodermal enhancer, we show that this regulatory element is necessary for the activation of the Igf2 and H19 genes upon induction of liver carcinogenesis. Furthermore, multiple sites of the H19 endodermal enhancer region become hypersensitive to DNase I when the carcinogenesis process is induced. Lastly, liver tumors developed in mice paternally inheriting the H19 enhancer deletion are found to have marked growth delays, increased frequency of apoptotic nuclei, and lack of Igf2 mRNA expression, thus indicating that this regulatory element plays a major role in the progression of liver carcinogenesis, since it is required for the activation of the anti-apoptotic Igf2 gene.
Animals↗
Telomere maintenance mechanisms as a target for drug development.
The shortening of the telomeric DNA sequences at the ends of chromosomes is thought to play a critical role in regulating the lifespan of human cells. Since all dividing cells are subject to the loss of telomeric sequences, cells with long proliferative lifespans need mechanisms to maintain telomere integrity. It appears that the activation of the enzyme telomerase is the major mechanism by which these cells maintain their telomeres. The proposal that a critical step in the process of the malignant transformation of cells is the upregulation of expression of telomerase has made this enzyme a potentially useful prognostic and diagnostic marker for cancer, as well as a new target for therapeutic intervention for the treatment of patients with cancer. It is now clear that simply inhibiting telomerase may not result in the anticancer effects that were originally hypothesized. While telomerase may not be the universal target for cancer therapy, we certainly believe that targeting the telomere maintenance mechanisms will be important in future research aimed toward a successful strategy for curing cancer.
Animals↗