tretinoin and Chromosome-Deletion

Translocations involving a variety of fusion partners, such as promyelocytic leukemia gene, promyelocytic leukemia zinc finger, nucleophosmin, nuclear matrix protein, and signal transducer and activator of transcription protein 5B, with the retinoic acid receptor alpha gene are commonly associated with development of acute promyelocytic leukemia. Through the development of transgenic mouse models, some retinoic acid receptor alpha translocation fusion proteins have been shown to be capable of initiating acute promyelocytic leukemia development, and dictate the leukemias' responsiveness to retinoic acid. Transgenic mouse models also have identified the influence of reciprocal translocation fusion proteins on acute promyelocytic leukemia development, and have demonstrated that additional mutations can contribute to the development of acute promyelocytic leukemia. In this review, the authors summarize current mouse models of acute promyelocytic leukemia and describe current knowledge about additional genetic alterations that occur during development of acute promyelocytic leukemia in the mouse.

Topics: Animals; Antineoplastic Agents; Arsenic; Chromosome Deletion; Disease Models, Animal; Leukemia, Promyelocytic, Acute; Mice; Models, Biological; Mutation; Neoplasm Proteins; Oncogene Proteins, Fusion; Tretinoin

To account for the complex genetics, the developmental biology, and the late adolescent/early adulthood onset of schizophrenia, the "two-hit" hypothesis has gained increasing attention. In this model, genetic or environmental factors disrupt early central nervous system (CNS) development. These early disruptions produce long-term vulnerability to a "second hit" that then leads to the onset of schizophrenia symptoms. The cell-cell signaling pathways involved in nonaxial induction, morphogenesis, and differentiation in the brain, as well as in the limbs and face, could be targets for a "first hit" during early development. These same pathways, redeployed for neuronal maintenance rather than morphogenesis, may be targets for a "second hit" in the adolescent or adult brain. Furthermore, dysregulation of cell-cell signaling by a "first hit" may prime the CNS for a pathologic response to a "second hit" via the same signaling pathway. Thus, parallel disruption of cell-cell signaling in both the developing and the mature CNS provides a plausible way of integrating genetic, developmental, and environmental factors that contribute to vulnerability and pathogenesis in schizophrenia.

Topics: Brain; Cell Communication; Chromosome Deletion; Chromosomes, Human, Pair 22; Environment; Humans; Neural Pathways; Psychological Theory; Schizophrenia; Tretinoin

DiGeorge syndrome (DGS) is a developmental defect which associates hypo- or aplasia of the thymus and parathyroids, facial dysmorphism and conotruncal cardiac malformations. The etiological factor in a great majority of DGS patients is monosomy for the 22q11.2 chromosomal region either through a large interstitial deletion of that region (inherited or de novo) or through an unbalanced translocation involving chromosome 22. In one instance, a balanced translocation of chromosome 22 was associated with a DGS phenotype. Extensive analyses of this region of chromosome 22 has led to the obtention of precise physical maps of the corresponding genomic region, to the cloning of the balanced translocation breakpoint and to the isolation of different genes from the minimal critical deleted region.

Topics: Abnormalities, Drug-Induced; Abnormalities, Multiple; Animals; Chromosome Aberrations; Chromosome Deletion; Chromosome Disorders; Chromosome Mapping; Chromosomes, Human, Pair 22; DiGeorge Syndrome; Female; Genes; Humans; Infant, Newborn; Male; Pregnancy; Pregnancy Complications; Rats; Syndrome; Translocation, Genetic; Tretinoin

All-trans-retinoic acid (ATRA) alone or in combination with cytokines and vitamins has been shown to stimulate erythropoiesis in low-risk myelodysplastic syndromes (MDS). We performed a phase II study on 29 patients with MDS and isolated del(5q) including bands q31-q33 to determine the efficacy and safety of ATRA in combination with tocopherol-alpha. All patients had low/intermediate-1 risk MDS according to the international prognostic scoring system. They received 45 mg/m(2) ATRA on days 1 to 90, and 90 mg/m(2) on days 91 to 180. Tocopherol dosage was 600 IU three times daily. Twenty-four patients completed dose level I, and 12 patients dose level II. Eighty-six percent of patients experienced side effects. Thirty discontinued the drug treatment due to such events as skin reactions, cheilitis, conjunctivitis, joint pain, creatinine increase, or CNS symptoms. One patient (3%) achieved a major erythroid response resulting in transfusion independence throughout the study. Four patients (14%) achieved a minor erythroid response with >50% reduction of transfusion needs. None of the participants had a cytogenetic response. There was no significant improvement in quality of life among responding patients as measured by the European Organization for the Research and Treatment of Cancer (EORTC) quality of life questionnaire. Based on these results, the combination of ATRA and tocopherol-alpha is not recommended for the treatment of del(5q) MDS.

Topics: Adult; Aged; Aged, 80 and over; alpha-Tocopherol; Bone Marrow; Chromosome Banding; Chromosome Deletion; Chromosomes, Human, Pair 5; Drug Eruptions; Drug Therapy, Combination; Erythropoiesis; Follow-Up Studies; Hemoglobins; Humans; In Situ Hybridization, Fluorescence; Middle Aged; Myelodysplastic Syndromes; Quality of Life; Treatment Outcome; Tretinoin

High-risk neuroblastomas typically display an undifferentiated or poorly differentiated morphology. It is therefore vital to understand molecular mechanisms that block the differentiation process. We identify an important role for oncogenic ALK-ERK1/2-SP1 signaling in the maintenance of undifferentiated neural crest-derived progenitors through the repression of DLG2, a candidate tumor suppressor gene in neuroblastoma. DLG2 is expressed in the murine "bridge signature" that represents the transcriptional transition state when neural crest cells or Schwann cell precursors differentiate to chromaffin cells of the adrenal gland. We show that the restoration of DLG2 expression spontaneously drives neuroblastoma cell differentiation, highlighting the importance of DLG2 in this process. These findings are supported by genetic analyses of high-risk 11q deletion neuroblastomas, which identified genetic lesions in the DLG2 gene. Our data also suggest that further exploration of other bridge genes may help elucidate the mechanisms underlying the differentiation of NC-derived progenitors and their contribution to neuroblastomas.

Topics: Adrenergic Agents; Anaplastic Lymphoma Kinase; Animals; Carcinogenesis; Cell Differentiation; Cell Line, Tumor; Cell Proliferation; Chromaffin Cells; Chromosome Deletion; Chromosomes, Human, Pair 11; Female; Gene Expression Regulation, Neoplastic; Guanylate Kinases; Humans; MAP Kinase Signaling System; Mice, Inbred BALB C; Nerve Growth Factor; Neuroblastoma; Neurons; Phenotype; Prognosis; Schwann Cells; Sp1 Transcription Factor; Transcription, Genetic; Treatment Outcome; Tretinoin; Tumor Suppressor Proteins; Up-Regulation

Purpose Most anemic patients with non-deleted 5q lower-risk myelodysplastic syndromes (MDS) are treated with erythropoiesis-stimulating agents (ESAs), with a response rate of approximately 50%. Second-line treatments, including hypomethylating agents (HMAs), lenalidomide (LEN), and investigational drugs, may be used after ESA failure in some countries, but their effect on disease progression and overall survival (OS) is unknown. Here, we analyzed outcome after ESA failure and the effect of second-line treatments. Patients and Methods We examined an international retrospective cohort of 1,698 patients with non-del(5q) lower-risk MDS treated with ESAs. Results Erythroid response to ESAs was 61.5%, and median response duration was 17 months. Of 1,147 patients experiencing ESA failure, 653 experienced primary failure and 494 experienced relapse after a response. Primary failure of ESAs was associated with a higher risk of acute myeloid leukemia (AML) progression, which did not translate into an OS difference. Of 450 patients (39%) who received second-line treatment, 194 received HMAs, 148 received LEN, and 108 received other treatments (MISC), whereas 697 received RBC transfusions only. Five-year AML cumulative incidence was 20.3%, 20.3%, and 11.3% for those receiving HMAs, LEN, and MISC, respectively ( P = .05). Five-year OS for patients receiving HMA, LEN, and MISC was 36.5%, 41.7%, and 51%, respectively ( P = .21). In a multivariable analysis adjusted for age, sex, revised International Prognostic Scoring System score, and progression at ESA failure, there was no significant OS difference among the three groups. Conclusion In this large, multicenter, retrospective cohort of patients with non-del(5q) lower-risk MDS treated with ESAs, none of the most commonly used second-line treatments (HMA and LEN) significantly improved OS. Early failure of ESAs was associated with a higher risk of AML progression.

Topics: Aged; Aged, 80 and over; Anemia; Antilymphocyte Serum; Antineoplastic Agents; Arsenic; Azacitidine; Chromosome Deletion; Chromosomes, Human, Pair 5; Cyclosporine; Cytarabine; Decitabine; Disease Progression; Enzyme Inhibitors; Erythrocyte Transfusion; Female; Hematinics; Humans; Hydroxyurea; Immunologic Factors; Lenalidomide; Leukemia, Myeloid, Acute; Male; Middle Aged; Myelodysplastic Syndromes; Recurrence; Retreatment; Retrospective Studies; Risk Factors; Survival Rate; Thalidomide; Treatment Failure; Tretinoin; Valproic Acid

We assessed feeding-related developmental anomalies in the LgDel mouse model of chromosome 22q11 deletion syndrome (22q11DS), a common developmental disorder that frequently includes perinatal dysphagia--debilitating feeding, swallowing and nutrition difficulties from birth onward--within its phenotypic spectrum. LgDel pups gain significantly less weight during the first postnatal weeks, and have several signs of respiratory infections due to food aspiration. Most 22q11 genes are expressed in anlagen of craniofacial and brainstem regions critical for feeding and swallowing, and diminished expression in LgDel embryos apparently compromises development of these regions. Palate and jaw anomalies indicate divergent oro-facial morphogenesis. Altered expression and patterning of hindbrain transcriptional regulators, especially those related to retinoic acid (RA) signaling, prefigures these disruptions. Subsequently, gene expression, axon growth and sensory ganglion formation in the trigeminal (V), glossopharyngeal (IX) or vagus (X) cranial nerves (CNs) that innervate targets essential for feeding, swallowing and digestion are disrupted. Posterior CN IX and X ganglia anomalies primarily reflect diminished dosage of the 22q11DS candidate gene Tbx1. Genetic modification of RA signaling in LgDel embryos rescues the anterior CN V phenotype and returns expression levels or pattern of RA-sensitive genes to those in wild-type embryos. Thus, diminished 22q11 gene dosage, including but not limited to Tbx1, disrupts oro-facial and CN development by modifying RA-modulated anterior-posterior hindbrain differentiation. These disruptions likely contribute to dysphagia in infants and young children with 22q11DS.

Topics: Animals; Animals, Newborn; Body Patterning; Chromosome Deletion; Cranial Nerves; Craniofacial Abnormalities; Deglutition; Deglutition Disorders; DiGeorge Syndrome; Disease Models, Animal; Embryo, Mammalian; Feeding Behavior; Female; Gene Dosage; Gene Expression Regulation, Developmental; Male; Mice; Phenotype; Rhombencephalon; Signal Transduction; T-Box Domain Proteins; Tretinoin

Myelodysplastic syndromes (MDS) are a group of hematopoietic malignancies characterized by ineffective hematopoiesis. Recently, we identified MDS-associated microRNAs (miRNAs) that are down-regulated in MDS. This study examines possible explanations for that observed down-regulation of miRNA expression in MDS. Since genomic losses are insufficient to explain the down-regulation of all our MDS-associated miRNAs, we explored other avenues. We demonstrate that these miRNAs are predominantly intragenic, and that, in many cases, they and their host genes are expressed in a similar pattern during myeloid maturation, suggesting their co-regulation. This co-regulation is further supported by the down-regulation of several of the host genes in MDS and increased methylation of the shared promoters of several miRNAs and their respective host genes. These studies identify a role of hypermethylation of miRNA promoters in the down-regulation of MDS-associated miRNAs, unifying research on miRNAs in MDS and epigenetic regulation in MDS into a common pathway.

Topics: Cell Differentiation; Cell Line, Tumor; Chromosome Deletion; Chromosome Mapping; CpG Islands; DNA Methylation; Gene Expression Regulation; Humans; MicroRNAs; Myelodysplastic Syndromes; Promoter Regions, Genetic; Transcriptome; Tretinoin

Rare, recurrent genomic imbalances facilitate the association of genotype with abnormalities at the "whole body" level. However, at the cellular level, the functional consequences of recurrent genomic abnormalities and how they can be linked to the phenotype are much less investigated.. We report an example of a functional analysis of two genes from a new, overlapping microdeletion of 2p13.2 region (from 72,140,702-72,924,626). The subjects shared intellectual disability (ID), language delay, hyperactivity, facial asymmetry, ear malformations, and vertebral and/or craniofacial abnormalities. The overlapping region included two genes, EXOC6B and CYP26B1, which are involved in exocytosis/Notch signaling and retinoic acid (RA) metabolism, respectively, and are of critical importance for early morphogenesis, symmetry as well as craniofacial, skeleton and brain development. The abnormal function of EXOC6B was documented in patient lymphoblasts by its reduced expression and with perturbed expression of Notch signaling pathway genes HES1 and RBPJ, previously noted to be the consequence of EXOC6B dysfunction in animal and cell line models. Similarly, the function of CYP26B1 was affected by the deletion since the retinoic acid induced expression of this gene in patient lymphoblasts was significantly lower compared to controls (8% of controls).. Haploinsufficiency of CYP26B1 and EXOC6B genes involved in retinoic acid and exocyst/Notch signaling pathways, respectively, has not been reported previously in humans. The developmental anomalies and phenotypic features of our subjects are in keeping with the dysfunction of these genes, considering their known role. Documenting their dysfunction at the cellular level in patient cells enhanced our understanding of biological processes which contribute to the clinical phenotype.

Topics: Abnormalities, Multiple; Adolescent; Bone Diseases, Developmental; Cell Line; Child; Chromosome Deletion; Chromosomes, Human, Pair 2; Craniofacial Abnormalities; Cytochrome P-450 Enzyme System; Developmental Disabilities; Exocytosis; Genotype; GTP-Binding Proteins; Haploinsufficiency; Humans; Male; Oligonucleotide Array Sequence Analysis; Phenotype; Retinoic Acid 4-Hydroxylase; Tretinoin

Topics: Animals; Chromatin; Chromosome Deletion; Chromosomes, Mammalian; DiGeorge Syndrome; Genetic Predisposition to Disease; Histone Acetyltransferases; Mice; Mutation; T-Box Domain Proteins; Tretinoin

We describe a patient with acute myeloid leukemia with myelodysplasia-related changes (AML-MRC) that clinically resembled acute promyelocytic leukemia (APL). The karyotype of his leukemic cells was 46, XY, del (3) (q?) and did not include a chromosomal translocation involving the retinoic acid receptor-α gene. However, retinoic acid syndrome developed, and partial remission was achieved after treatment with all-trans retinoic acid (ATRA) followed by chemotherapy. Our case might provide new insights into the mechanism of the growth inhibitory effect of ATRA on APL-like cells.

Topics: Aged; Antineoplastic Agents; Chromosome Deletion; Chromosomes, Human, Pair 3; Diagnosis, Differential; Humans; Leukemia, Myeloid, Acute; Leukemia, Promyelocytic, Acute; Male; Myelodysplastic Syndromes; Oncogene Proteins, Fusion; Tretinoin

Large-scale hemizygous loss of chromosome 3p is a common event in neuroblastoma, occurring preferentially in tumors that exhibit loss of chromosome 11q and lack MYCN amplification. Although numerous tumor suppressor genes (TSG) have been mapped to the 3p region, the gene or genes contributing to neuroblastoma pathogenesis have remained elusive. High-resolution oligonucleotide array CGH mapping of chromosome 3p breakpoints relative to the positions of known TSGs indicates that more than one gene may contribute to neuroblastoma pathogenesis. We evaluated the methylation status of semaphorin 3B (SEMA3B), one of the chromosome 3p TSGs, in neuroblastoma tumors with (n = 12) and without (n = 32) 3p deletions. A significantly higher percentage of methylated CpG sites in the SEMA3B promoter was detected in tumors exhibiting 3p loss (95%), relative to tumors without loss (52%), suggestive of a two-hit mechanism of allele inactivation. The involvement of methylation in the control of SEMA3B expression was confirmed by treatment of neuroblastoma cell lines with the demethylating agent 5-aza-2-deoxycytidine. Transcriptional regulation of this locus is complex, however; low levels of SEMA3B expression were also seen in tumors with unmethylated SEMA3B promoters (n = 4). SEMA3B is known to play an important role in the development of normal sympathetic neurons, and interestingly, we found higher levels of SEMA3B expression in differentiated tumors with favorable histopathology (n = 19) than in tumors with unfavorable histology (n = 22). Furthermore, SEMA3B was upregulated in the SK-N-BE neuroblastoma cell line following induction of differentiation with retinoic acid. The association of SEMA3B expression with neuroblastoma differentiation suggests that this TSG may play a role in neuroblastoma pathobiology.

Topics: Adolescent; Antineoplastic Agents; Azacitidine; Base Sequence; Cell Differentiation; Cell Line; Cell Line, Tumor; Child; Child, Preschool; Chromosome Breakage; Chromosome Deletion; Chromosomes, Human, Pair 3; CpG Islands; Decitabine; DNA Methylation; Gene Expression Regulation, Neoplastic; Genes, Tumor Suppressor; Humans; Infant; Membrane Glycoproteins; Molecular Sequence Data; Neuroblastoma; Nucleic Acid Hybridization; Reverse Transcriptase Polymerase Chain Reaction; Semaphorins; Tretinoin

Retinoids' effects on cell growth and differentiation are mediated by nuclear retinoid receptors, which are ligand-activated transcription enhancing factors. Because the expression of the retinoic acid receptor beta (RARbeta) gene, which is located on chromosome 3p24, is diminished in premalignant and malignant tissues it has been proposed that it acts as a tumor suppressor. To test the hypothesis that RARbeta loss leads to retinoid resistance, we studied several karyotyped head and neck squamous carcinoma (HNSCC) cell lines (UMSCC-17A, -17B, -22A, -22B, and -38) with deletion of one chromosome 3p arm. RARbeta mRNA was neither detected nor induced by retinoic acid in these cells, whereas it was expressed and induced by retinoic acid in two other HNSCC cell lines (1483 and 183) without 3p deletion. Methylation of the RARbeta gene promoter was detected in the 17B and 22B cells that failed to express RARbeta but no methylation was found in 183A cells that did express RARbeta mRNA. Responsiveness of HNSCC cells to several retinoids in assays of growth inhibition and colony formation, was rank ordered as: 22B>1483>38>183>17B. Additionally, retinoid response elements were transactivated in 22B more efficiently than in 17B cells. These results indicate that loss of RARbeta expression does not necessarily lead to loss of growth inhibition by retinoids or to a block of retinoid signaling.

Topics: Antineoplastic Agents; Carcinoma, Squamous Cell; Cell Division; Chromosome Deletion; Chromosomes, Human, Pair 3; DNA, Neoplasm; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Genes, Tumor Suppressor; Head and Neck Neoplasms; Humans; Promoter Regions, Genetic; Receptors, Retinoic Acid; Retinoids; RNA, Neoplasm; Transcriptional Activation; Tretinoin; Tumor Cells, Cultured

We report a unique case of de novo acute promyelocytic leukemia (APL) with cryptic 15;17 rearrangements. Cytogenetically, structural rearrangements of the 6p23 region has been reported mainly in secondary leukemia. This patient had a karyotype of 46, XY, del(6)(p23) and no additional chromosomal abnormalities. Molecular analyses revealed the presence of PML-RAR alpha fusion genes. Deletion of the 6p23 region is extremely rare in APL.

Topics: Aged; Antineoplastic Combined Chemotherapy Protocols; Chromosome Deletion; Chromosomes, Human, Pair 15; Chromosomes, Human, Pair 17; Chromosomes, Human, Pair 6; Cytarabine; Humans; Idarubicin; Karyotyping; Leukemia, Promyelocytic, Acute; Male; Neoplasm Proteins; Oncogene Proteins, Fusion; Remission Induction; Reverse Transcriptase Polymerase Chain Reaction; Tretinoin

Tumor cell resistance to doxorubicin (DOX) is usually associated with the overexpression of P-glycoprotein (PGP) in model systems. We have characterized the karyotypic changes in two sublines of HL-60 cells which differ in the induction of differentiation by retinoic acid. The parental sublines, designated HL-60A/S and HL-60Y/S, were selected in increasing concentrations of 0.025-0.1 micrograms/mL DOX. Monosomy 8 in HL-60Y/S was the only karyotypic difference prior to DOX exposure. Both sublines acquired 7q+ markers upon exposure to DOX. In HL-60Y/S, and add(7)(q21) replaced one homologue at 0.025 micrograms/mL DOX, and an add(7)(q32) appeared which replaced the other normal 7 at 0.05 micrograms/mL DOX. The HL-60A/S cells acquired an add(7)(q21) at 0.025 micrograms/mL DOX. The 7q+ abnormalities involved breakpoints in the midregion of 7q. The overexpression of phosphorylated PGP in immunoprecipitates with C-219 antibody was identified in both sublines of DOX-resistant HL-60 cells with 7q+ abnormalities, and this is consistent with the location of mdr-1 sequences to 7q21-21.1. Also, analysis of RNA from parental-sensitive and DOX-resistant sublines by reverse transcriptase-polymerase chain reaction revealed: a) comparable expression of multidrug resistance related protein (MPR) in sensitive and resistant sublines; and b) overexpression of mdr-1 only in the DOX-resistant sublines. Thus, the selection of DOX resistance in two sublines of HL-60 cells which differ in their response to retinoic acid-induced myeloid differentiation is reproducibly associated with overexpression of mdr-1 versus MRP.

Topics: Antibiotics, Antineoplastic; ATP Binding Cassette Transporter, Subfamily B, Member 1; Chromosome Aberrations; Chromosome Deletion; Chromosomes, Human, Pair 7; Doxorubicin; Drug Resistance, Neoplasm; HL-60 Cells; Humans; Karyotyping; Polymerase Chain Reaction; Reproducibility of Results; Tretinoin

Thyroid hormones and retinoic acid function through nuclear receptors that belong to the steroid/thyroid-hormone receptor superfamily. Thyroid hormone receptors (TRs) and retinoic acid receptors (RARs) require auxiliary nuclear proteins for efficient DNA binding. Here we report that retinoid X receptors RXR alpha is one of these nuclear proteins. RXR alpha interacts both with TRs and with RARs, forming heterodimers in solution that strongly interact with a variety of T3/retinoic acid response elements. Transfection experiments show that RXR alpha can greatly enhance the transcriptional activity of TR and RAR at low retinoic acid concentrations that do not significantly activate RXR alpha itself. Thus, RXR alpha enhances the transcriptional activity of other receptors and its own ligand sensitivity by heterodimer formation. Our studies reveal a new subclass of receptors and a regulatory pathway controlling nuclear receptor activities by heterodimer formation.

Topics: Animals; Base Sequence; Carrier Proteins; Cell Line; Chromosome Deletion; Cloning, Molecular; DNA-Binding Proteins; Female; Gene Library; Humans; Kinetics; Macromolecular Substances; Molecular Sequence Data; Nuclear Proteins; Oligodeoxyribonucleotides; Placenta; Polymerase Chain Reaction; Pregnancy; Protein Biosynthesis; Receptors, Cell Surface; Receptors, Retinoic Acid; Receptors, Thyroid Hormone; Restriction Mapping; Retinoid X Receptors; Transcription Factors; Transcription, Genetic; Transfection; Tretinoin; Triiodothyronine

Mammalian alcohol dehydrogenase (ADH) catalyzes the oxidation of retinol to retinaldehyde, the rate-limiting step in the synthesis of retinoic acid. There exists a family of ADH isozymes encoded by unique genes, and it is unclear which isozymes are most important for regulation of retinoic acid synthesis during differentiation or development. A region in the human ADH3 promoter from -328 to -272 base pairs was shown previously to function as a retinoic acid response element (RARE), prompting an hypothesis for a positive feedback mechanism controlling retinoic acid synthesis (Duester, G., Shean, M. L., McBride, M. S., and Stewart, M. J. (1991) Mol. Cell. Biol. 11, 1638-1646). The ADH3 RARE contains three direct AGGTCA repeats which constitute the critical nucleotides of RAREs present in other genes. We dissected the ADH3 RARE and determined that receptor binding as well as transactivation are dependent upon only the two downstream AGGTCA motifs separated by 5 base pairs, a structure noticed previously for a RARE in the promoter for the retinoic acid receptor beta (RAR beta) gene. ADH3 and RAR beta RAREs functioned similarly in transfection assays, suggesting that the feedback mechanisms controlling ADH3 and RAR beta utilize a common RARE. We also found that the normal functioning of the ADH3 RARE was abrogated by thyroid hormone receptor in the presence of thyroid hormone. A negative thyroid hormone response element in the human ADH3 promoter was found to colocalize with the RARE. Since ADH production in rat liver is known to be repressed by thyroid hormone, these findings suggest that human ADH production may also be subject to thyroid hormone repression and that the mechanism involves an interference with retinoic acid induction.

Topics: Alcohol Dehydrogenase; Animals; Base Sequence; Carrier Proteins; Cell Nucleus; Chromosome Deletion; Enzyme Repression; Gene Expression Regulation, Enzymologic; HeLa Cells; Humans; Isoenzymes; Liver; Mammary Tumor Virus, Mouse; Molecular Sequence Data; Oligonucleotide Probes; Plasmids; Promoter Regions, Genetic; Rats; Receptors, Retinoic Acid; Repetitive Sequences, Nucleic Acid; Thyroid Hormones; Tretinoin

As in other embryocarcinoma (EC) cell lines retinoic acid (RA) rapidly induces expression of the nuclear retinoic acid receptor (RAR) beta in murine P19 EC cells, while RAR alpha is expressed constitutively. In the RA-resistant P19 EC-derived RAC65 cells, however, there is no such induction and an aberrant (smaller) RAR alpha transcript is expressed. RAR gamma 1 is expressed at low levels in both cell lines. To study the regulation of the RAR beta gene and the possible involvement of RAR alpha protein in transcriptional activation of the RAR beta gene we transfected these cells with a construct containing a 1.6 kb promoter fragment of the human RAR beta gene fused to the CAT gene. Upon transient assays in P19 EC cells CAT activity is enhanced rapidly by RA, to more than 100-fold in a concentration-dependent fashion. On the contrary no activity can be observed in the RA-resistant RAC65 cells; however, co-transfection of hRAR alpha, hRAR beta or hRAR gamma 1 restores the RA-dependent induction of CAT activity. These results clearly show that RAR alpha and RAR gamma 1 can transactivate the RAR beta gene; that RAR beta can stimulate its own expression and that resistance to RA in RAC65 cells is probably due to the altered RAR alpha transcript present in these cells.

Topics: Animals; Base Sequence; Carrier Proteins; Chromosome Deletion; Drug Resistance; Embryonal Carcinoma Stem Cells; Gene Expression Regulation, Neoplastic; Mice; Molecular Sequence Data; Neoplasm Proteins; Neoplastic Stem Cells; Promoter Regions, Genetic; Receptors, Retinoic Acid; RNA, Neoplasm; Transcription, Genetic; Transfection; Tretinoin; Tumor Cells, Cultured

Retinoids are known to have profound effects on cellular differentiation and embryo pattern formation. In the adult organism, retinoid acid (RA) receptors are present in a large variety of tissues, including brain. However, little is known of the precise roles of RA at these different sites. In the present study we have identified a novel potential target of RA action by identifying an RA response element (RARE) in the human oxytocin (OT) gene promoter. We have used DNA-mediated gene transfer techniques to introduce various portions of the OT 5'-flanking sequences next to the chloramphenicol acetyltransferase (CAT) gene in neuroblastoma cells. RA elicited a marked stimulation of the transcriptional activity of the OT promoter in cells cotransfected with either the human RA receptor alpha, beta, or gamma. In cells cotransfected with the RA receptor alpha, the ED50 of this response was 5 x 10(-10) M. The RA response could also be conferred to a heterologous promoter independent of orientation. 5'-Deletions as well as site-directed mutations demonstrated that four TGACC motifs, located at -162, -156, -103, and -83 in the OT promoter, are necessary for optimal RA induction. Mutation or deletion of any of these elements reduces significantly the RA response. Interestingly, the first two TGACC motifs overlap with the estrogen response element that we have previously characterized in this gene. Furthermore, the TGACC motif located at -83 overlaps with the CCAAT box. We further demonstrate that in neuroblastoma cells transfected with an RAR alpha expression vector expression of the endogenous OT gene is stimulated greater than 4-fold in response to RA. Our studies constitute the first report of a RARE in a neuropeptide gene and define a mechanism by which OT gene expression can be modulated by retinoic acid.

Topics: Animals; Base Sequence; Binding Sites; Carrier Proteins; Cattle; Cell Line; Chloramphenicol O-Acetyltransferase; Chromosome Deletion; Gene Expression; Humans; Hypothalamus; Mice; Mice, Inbred BALB C; Molecular Sequence Data; Mutagenesis, Site-Directed; Oligodeoxyribonucleotides; Oxytocin; Plasmids; Promoter Regions, Genetic; Rats; Receptors, Retinoic Acid; Restriction Mapping; Sequence Homology, Nucleic Acid; Transfection; Tretinoin

Retinoic acid, the first morphogen described so far in vertebrates, is a vitamin A derivative which exerts striking effects on development and differentiation. The identification of three retinoic acid receptors as members of the nuclear receptor super-family provides an explantation for the molecular action of morphogens on gene expression. Functional analysis of the receptors requires the identification of target genes and of their cis-acting retinoic acid-responsive elements. We have previously shown that the retinoic acid receptor beta gene is transcriptionally up-regulated by retinoic acid and now report the characterization of a functional retinoic acid responsive element in the beta gene that mediates trans-activation by retinoic acid. Using deletion mapping, we have identified a 27-base pair fragment, located 59 base pairs upstream of the transcriptional start, which confers retinoic acid responsiveness on the herpes virus thymidine kinase promoter. This sequence contains a perfect direct repeat of the motif GTTCAC, which is reminiscent of the 5' half-palindrome of the thyroid and oestrogen hormone responsive elements. Specific binding of the beta protein to the retinoic acid responsive element is demonstrated and is independent of the presence of retinoic acid. Both alpha and beta receptors enhance retinoic acid response in CV1 cells, indicating that they can both act through the same DNA sequence.

Topics: Base Sequence; Carrier Proteins; Chromosome Deletion; Cloning, Molecular; Genes; Genes, Regulator; Humans; Molecular Sequence Data; Oligonucleotide Probes; Promoter Regions, Genetic; Receptors, Retinoic Acid; Restriction Mapping; RNA, Messenger; Transcription, Genetic; Tretinoin

We present evidence that the vitamin D response element in the human osteocalcin gene confers responsiveness to the vitamin A metabolite, retinoic acid. Retinoic acid receptor (RAR) expressed in E. coli binds to this sequence in vitro. Transfection of RAR expression vectors in cultured cells activates heterologous promoters containing this sequence in vivo. This response element contains a consensus AP-1 site TGACTCA and in vitro is bound by the Jun-Fos complex. Unexpectedly, cotransfection of Jun and Fos expression vectors suppresses basal level transcription of the osteocalcin gene and suppresses induction by both retinoic acid and vitamin D3. Additional studies delimit an 11 nucleotide segment as a minimal hormone response element containing the AP-1 site as its core. These results indicate that two distinct classes of transcription factors can recognize common regulatory sequences, a phenomenon we refer to as cross-coupling.

Topics: Animals; Base Sequence; Binding Sites; Carrier Proteins; Cell Line; Cholecalciferol; Chromosome Deletion; DNA-Binding Proteins; Genes; Humans; Molecular Sequence Data; Mutation; Osteocalcin; Promoter Regions, Genetic; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-fos; Proto-Oncogene Proteins c-jun; Receptors, Cell Surface; Receptors, Retinoic Acid; Restriction Mapping; Sequence Homology, Nucleic Acid; Transcription Factors; Transcription, Genetic; Transfection; Tretinoin

F9 cells induced to differentiate with retinoic acid (RA) increase transcription of the tissue plasminogen activator (t-PA) gene. Further treatment of these cells with cyclic AMP (cAMP) results in an additional stimulation of t-PA gene transcription. To investigate the mechanism of this two-stage regulation, 4 kilobase pairs (kbp) of 5'-flanking sequence from the murine t-PA gene was isolated. Two major start sites for transcription were found, neither of which depended on a classical TATA motif for correct initiation. By using transient transfection assays, it was determined that 4-kbp of flanking sequence could confer on reporter genes the same two-stage differentiation-specific expression as was observed for the endogenous t-PA gene. Deletion analyses of this 4-kbp fragment showed that 190 bp of flanking sequence was sufficient to bestow the same degree of two-stage regulation on reporter gene constructs. Within this region of DNA, sequence analysis revealed a possible cAMP regulatory element, a CTF/NF-1 recognition sequence, two potential Sp1 sites, and five potential binding sites for transcription factor AP-2. The deletion experiments, coupled with the positions of these potential cis-acting elements, suggest that multiple transcription factors, including those that bind to cAMP regulatory element, CTF/NF-1, Sp1, and AP-2 sites, may be involved in regulation of the t-PA gene during F9 cell differentiation.

Topics: Animals; Base Sequence; Cell Differentiation; Chromosome Deletion; Chromosome Mapping; Cyclic AMP; DNA, Neoplasm; Gene Expression Regulation; Mice; Molecular Sequence Data; Promoter Regions, Genetic; Teratoma; Tissue Plasminogen Activator; Transcription, Genetic; Tretinoin; Tumor Cells, Cultured

We present evidence that the human thyroid hormone receptor forms a heterodimer with the human retinoic acid receptor. This interaction results in a cooperative increase in binding of the alpha retinoic acid receptor to a subset of thyroid hormone response elements. Mutations within the DNA binding domain or near the C-terminus abolish either receptor's ability to interact cooperatively on these elements. The thyroid hormone-retinoic acid receptor heterodimer exhibits novel transcriptional properties in that coexpression of both receptors at low levels in Green monkey kidney (CV1) cells results in a positive transcriptional effect on promoters containing a palindromic thyroid hormone response element, but has a surprisingly negative effect on a thyroid hormone response element derived from the alpha myosin heavy chain gene. These results suggest that by forming heterodimers, more elab-orate control of transcription can be achieved by creating receptor combinations with differing activities.

Topics: Amino Acid Sequence; Animals; Base Sequence; Carrier Proteins; Cell Line; Chromosome Deletion; DNA; DNA-Binding Proteins; Gene Expression Regulation; Genes; Humans; Macromolecular Substances; Molecular Sequence Data; Mutation; Oligonucleotide Probes; Protein Binding; Receptors, Retinoic Acid; Receptors, Thyroid Hormone; Transcription, Genetic; Transfection; Tretinoin