RESUMO
Head and neck squamous cell carcinoma (HNSCC) cells exposed to cisplatin (CIS) displayed a dramatic ATM-dependent phosphorylation of ΔNp63α that leads to the transcriptional regulation of downstream mRNAs. Here, we report that phospho (p)-ΔNp63α transcriptionally deregulates miRNA expression after CIS treatment. Several p-ΔNp63α-dependent microRNA species (miRNAs) were deregulated in HNSCC cells upon CIS exposure, including miR-181a, miR-519a, and miR-374a (downregulated) and miR-630 (upregulated). Deregulation of miRNA expression led to subsequent modulation of mRNA expression of several targets (TP53-S46, HIPK2, ATM, CDKN1A and 1B, CASP3, PARP1 and 2, DDIT1 and 4, BCL2 and BCL2L2, TP73, YES1, and YAP1) that are involved in the apoptotic process. Our data support the notion that miRNAs are critical downstream targets of p-ΔNp63α and mediate key pathways implicated in the response of cancer cells to chemotherapeutic drugs.
Assuntos
Antineoplásicos/farmacologia , Cisplatino/farmacologia , MicroRNAs/metabolismo , Fatores de Transcrição/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Apoptose , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/metabolismo , Linhagem Celular Tumoral , RNA Helicases DEAD-box/antagonistas & inibidores , RNA Helicases DEAD-box/genética , RNA Helicases DEAD-box/metabolismo , Regulação Neoplásica da Expressão Gênica , Neoplasias de Cabeça e Pescoço/genética , Neoplasias de Cabeça e Pescoço/metabolismo , Humanos , Fosforilação , Regiões Promotoras Genéticas , Ligação Proteica , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Ribonuclease III/antagonistas & inibidores , Ribonuclease III/genética , Ribonuclease III/metabolismo , Fatores de Transcrição/genética , Proteínas Supressoras de Tumor/genéticaRESUMO
To identify novel methylated gene promoters, we compared differential RNA expression profiles of colorectal cancer (CRC) cell lines with or without treatment of 5-aza-2'-deoxycytidine (5-aza-dC). Out of 1776 genes that were initially 'absent (that is, silenced)' by gene expression array analysis, we selected 163 genes that were increased after 5-aza-dC treatment in at least two of three CRC cell lines. The microarray results were confirmed by Reverse Transcription-PCR, and CpG island of the gene promoters were amplified and sequenced for examination of cancer-specific methylation. Among the genes identified, the deafness, autosomal dominant 5 gene, DFNA5, promoter was found to be methylated in primary tumor tissues with high frequency (65%, 65/100). Quantitative methylation-specific PCR of DFNA5 clearly discriminated primary CRC tissues from normal colon tissues (3%, 3/100). The mRNA expression of DFNA5 in four of five colon cancer tissues was significantly downregulated as compared to normal tissues. Moreover, forced expression of full-length DFNA5 in CRC cell lines markedly decreased the cell growth and colony-forming ability whereas knockdown of DFNA5 increased cell growth in culture. Our data implicate DFNA5 as a novel tumor suppressor gene in CRC and a valuable molecular marker for human cancer.
Assuntos
Carcinoma/genética , Neoplasias do Colo/patologia , Neoplasias Colorretais/genética , Regulação Neoplásica da Expressão Gênica , Regiões Promotoras Genéticas , Receptores de Estrogênio/genética , Receptores de Estrogênio/metabolismo , Linhagem Celular Tumoral , Proliferação de Células , Neoplasias do Colo/metabolismo , Metilação de DNA , Inativação Gênica , Genes Supressores de Tumor , Humanos , Modelos Biológicos , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
N-methyl-D-aspartate receptors (NMDARs) are the predominant excitatory neurotransmitter receptors in the mammalian brain. We found that among the three NMDARs examined (NMDAR1, NMDAR2A, NMDAR2B), only NMDAR2A was silenced in colorectal carcinoma (CRC) cell lines at basal line and reactivated by the demethylating agent, 5-aza-2'-deoxycytidine. NMDAR2A was expressed in normal colon epithelium, while expression was hardly detectable in colon cancer tissues. Promoter methylation of NMDAR2A was confirmed by bisulfite sequencing and combined bisulfite restriction analysis in the CRC cell lines and primary tumors. Quantitative methylation-specific PCR demonstrated NMDAR2A promoter hypermethylation in 82 of 100 primary human CRC, 15 of 100 normal corresponding epithelial tissues and 1 of 11 (9%) normal colon mucosa samples obtained from patients without cancer. Moreover, forced expression of full-length NMDAR2A in CRC cell lines induced apoptosis and almost abolished the ability of the cells to form colonies in culture, while NMDAR2A knockdown increased cell growth. Thus, NMDAR2A is commonly hypermethylated in primary human CRC and possesses tumor-suppressive activity.
Assuntos
Carcinoma/genética , Neoplasias Colorretais/genética , Metilação de DNA , Receptores de N-Metil-D-Aspartato/genética , Azacitidina/análogos & derivados , Azacitidina/farmacologia , Carcinoma/patologia , Proliferação de Células , Neoplasias Colorretais/patologia , Metilases de Modificação do DNA/antagonistas & inibidores , Decitabina , Humanos , Imuno-Histoquímica , Regiões Promotoras Genéticas , Receptores de N-Metil-D-Aspartato/análise , Análise Serial de TecidosRESUMO
Activated macrophages play a central role in antitumor immunity. However, the stimuli that activate macrophages to kill tumor cells are not completely understood. Because the center of solid tumors can be hypoxic, we hypothesized that hypoxia may be an important signal in activating macrophages to kill tumor cells. Hypoxia stimulates IFN-primed macrophages to express the inducible nitric oxide synthase (NOS2) and to synthesize nitric oxide (NO). We show that this synergy between IFN and hypoxia is mediated by the direct interaction of the hypoxia inducible factor-1 (HIF-1) and IFN regulatory factor-1 (IRF-1), which are both required for the hypoxic transcription of NOS2. This interaction between HIF-1 and IRF-1 may explain the mechanism by which macrophages infiltrating into tumors are activated to express NOS2 and to produce NO, a mediator of tumor apoptosis.
Assuntos
Apoptose/fisiologia , Proteínas de Ligação a DNA/fisiologia , Interferon gama/fisiologia , Macrófagos/imunologia , Óxido Nítrico/fisiologia , Proteínas Nucleares/fisiologia , Fosfoproteínas/fisiologia , Transdução de Sinais/fisiologia , Animais , Sítios de Ligação , Hipóxia Celular/fisiologia , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Indução Enzimática , Feminino , Fator 1 Induzível por Hipóxia , Subunidade alfa do Fator 1 Induzível por Hipóxia , Fator Regulador 1 de Interferon , Interferon gama/farmacologia , Ativação de Macrófagos/fisiologia , Macrófagos/enzimologia , Melanoma Experimental/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Óxido Nítrico Sintase/biossíntese , Óxido Nítrico Sintase/genética , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Saccharomyces cerevisiae/genética , Fatores de Transcrição/fisiologia , Ativação Transcricional , TransfecçãoRESUMO
A human p53 homologue, p63 (p40/p51/p73L/CUSP) that maps to the chromosomal region 3q27-29 was found to produce a variety of transcripts that encode DNA-binding proteins with and without a trans-activation domain (TA- or Delta N-, respectively). The p63 gene locus was found to be amplified in squamous cell carcinoma, and overexpression of Delta Np63 (p40) led to increased growth of transformed cells in vitro and in vivo. Moreover, p63-null mice displayed abnormal epithelial development and germ-line human mutations were found to cause ectodermal dysplasia. We now demonstrate that certain p63 isotypes form complexes with p53. p53 mutations R175H or R248W abolish the association of p53 with p63, whereas V143A or R273H has no effect. Deletion studies suggest that the DNA-binding domains of both p53 and p63 mediate the association. Overexpression of wild type but not mutant (R175H) p53 results in the caspase-dependent degradation of certain Delta Np63 proteins (p40 and Delta Np63 alpha). The association between p53 and Delta Np63 supports a previously unrecognized role for p53 in regulation of Delta Np63 stability. The ability of p53 to mediate Delta Np63 degradation may balance the capacity of Delta Np63 to accelerate tumorigenesis or to induce epithelial proliferation.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Genes Supressores de Tumor , Fosfoproteínas , Transativadores , Proteína Supressora de Tumor p53/metabolismo , Animais , Linhagem Celular , Núcleo Celular/metabolismo , Proteínas de Ligação a DNA/genética , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Saccharomyces cerevisiae , Células Tumorais Cultivadas , Proteína Supressora de Tumor p53/genéticaRESUMO
We and others recently isolated a human p53 homologue (p40/p51/p63/p73L) and localized the gene to the distal long arm of chromosome 3. Here we sought to examine the role of p40/p73L, two variants lacking the N-terminal transactivation domain, in cancer. Fluorescent in situ hybridization (FISH) analysis revealed frequent amplification of this gene locus in primary squamous cell carcinoma of the lung and head and neck cancer cell lines. (We named this locus AIS for amplified in squamous cell carcinoma.) Furthermore, amplification of the AIS locus was accompanied by RNA and protein overexpression of a variant p68(AIS) lacking the terminal transactivation domain. Protein overexpression in primary lung tumors was limited to squamous cell carcinoma and tumors known to harbor a high frequency of p53 mutations. Overexpression of p40(AIS) in Rat 1a cells led to an increase in soft agar growth and tumor size in mice. Our results support the idea that AIS plays an oncogenic role in human cancer.
Assuntos
Carcinoma de Células Escamosas/genética , Proteínas de Ligação a DNA/genética , Amplificação de Genes , Neoplasias de Cabeça e Pescoço/genética , Neoplasias Pulmonares/genética , Proteínas Nucleares/genética , Oncogenes , Processamento Alternativo , Animais , Carcinoma de Células Escamosas/patologia , Linhagem Celular , Mapeamento Cromossômico , Cromossomos Humanos Par 3 , Proteínas de Ligação a DNA/análise , Genes Supressores de Tumor , Genes p53 , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Imuno-Histoquímica , Hibridização in Situ Fluorescente , Neoplasias Pulmonares/patologia , Camundongos , Camundongos Nus , Proteínas Nucleares/análise , Fosfoproteínas , Ratos , Transativadores , Fatores de Transcrição , Transfecção , Transplante Heterólogo , Células Tumorais Cultivadas , Proteína Tumoral p73 , Proteínas Supressoras de TumorRESUMO
A variety of transcriptional and post-transcriptional mechanisms regulate the expression of the inducible nitric-oxide synthase (iNOS, or NOS2). Although neurons and endothelial cells express proteins that interact with and inhibit neuronal NOS and endothelial NOS, macrophage proteins that inhibit NOS2 have not been identified. We show that murine macrophages express a 110-kDa protein that interacts with NOS2, which we call NOS-associated protein-110 kDa (NAP110). NAP110 directly interacts with the amino terminus of NOS2, and inhibits NOS catalytic activity by preventing formation of NOS2 homodimers. Expression of NAP110 may be a mechanism by which macrophages expressing NOS2 protect themselves from cytotoxic levels of nitric oxide.
Assuntos
Óxido Nítrico Sintase/antagonistas & inibidores , Sequência de Aminoácidos , Animais , Linhagem Celular , Dimerização , Camundongos , Dados de Sequência Molecular , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico Sintase Tipo II , Isoformas de Proteínas/metabolismo , Especificidade por Substrato , Tunicamicina/farmacologia , Técnicas do Sistema de Duplo-HíbridoRESUMO
Nitric oxide (NO) acts as a neurotransmitter. However, excess NO produced from neuronal NO synthase (nNOS) or inducible NOS (iNOS) during inflammation of the central nervous system can be neurotoxic, disrupting neurotransmitter and hormone production and killing neurons. A screen of a hippocampal cDNA library showed that a unique region of the iNOS protein interacts with Kalirin, previously identified as an interactor with a secretory granule peptide biosynthetic enzyme. Kalirin associates with iNOS in vitro and in vivo and inhibits iNOS activity by preventing the formation of iNOS homodimers. Expression of exogenous Kalirin in pituitary cells dramatically reduces iNOS inhibition of ACTH secretion. Thus Kalirin may play a neuroprotective role during inflammation of the central nervous system by inhibiting iNOS activity.
Assuntos
Proteínas de Transporte , Inibidores Enzimáticos/farmacologia , Proteínas de Ligação ao GTP/metabolismo , Fatores de Troca do Nucleotídeo Guanina , Óxido Nítrico Sintase/antagonistas & inibidores , Hormônio Adrenocorticotrópico/metabolismo , Sequência de Aminoácidos , Animais , Linhagem Celular , Dimerização , Camundongos , Dados de Sequência Molecular , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico Sintase Tipo II , Proteínas Recombinantes/metabolismo , Células Tumorais CultivadasRESUMO
The G401 cell line derived from a rhabdoid tumor of the kidney secretes the heparin-binding growth factors midkine and pleiotrophin. Both proteins act as mitogens for diverse cells, but only midkine serves as an autocrine mitogen for G401 tumor cells. We show that midkine specifically binds a protein or complex of molecular mass greater than 200 kDa with high affinity (Kd = 0.07 +/- 0.01 nM). Midkine, but not pleiotrophin, stimulates tyrosine phosphorylation of several cellular proteins with molecular mass of 100, 130, and 200+ kDa. Upon midkine binding, the midkine-receptor complex associates with the Janus tyrosine kinases, JAK1 and JAK2. MK stimulates tyrosine phosphorylation of JAK1, JAK2, and STAT1alpha. Our initial characterization of the midkine receptor suggests that midkine autocrine stimulation of tumor cell proliferation is mediated by a cell-surface receptor which in turn might activate the JAK/STAT pathway.
Assuntos
Proteínas de Transporte/farmacologia , Divisão Celular/efeitos dos fármacos , Citocinas , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de Sinais , Animais , Linhagem Celular , Ativação Enzimática , Humanos , Janus Quinase 1 , Janus Quinase 2 , Midkina , Receptores de Superfície Celular/metabolismo , Células Tumorais CultivadasRESUMO
Midkine, but not pleiotrophin, is mitogenic to human Wilms' tumor cells (G401 line) in dose-dependent and time-dependent fashion. Midkine specifically binds to high affinity (Kd = 0.15 +/- 0.02 nM, 210 kDa) and low affinity receptors (Kd = 0.65 +/- 0.07 nM, 75 kDa) on G401 cell surface, that has been confirmed by cross-linking and competition experiments. In addition, midkine stimulates a tyrosine phosphorylation of several proteins with molecular weight about 110-115 kDa, 130-140 kDa and 210 kDa. These data allow us to suggest that a key point in stimulation of G401 cell proliferation is interaction of midkine to its signaling receptor.
Assuntos
Proteínas de Transporte/farmacologia , Divisão Celular/efeitos dos fármacos , Mitógenos/farmacologia , Receptores de Superfície Celular/efeitos dos fármacos , Receptores de Superfície Celular/metabolismo , Animais , Sequência de Bases , Células COS , Proteínas de Transporte/genética , Citocinas/genética , Citocinas/farmacologia , Primers do DNA/genética , Humanos , Neoplasias Renais/metabolismo , Cinética , Midkina , Peso Molecular , Proteínas de Neoplasias/química , Proteínas de Neoplasias/metabolismo , Fosforilação , Receptores de Superfície Celular/química , Transdução de Sinais , Células Tumorais Cultivadas , Tirosina/metabolismo , Tumor de Wilms/metabolismoRESUMO
The human interferon alpha-receptor (IFNAR gene product) is a transmembranal protein of 557 amino acids with an intracytoplasmic domain of 100 amino acids containing four tyrosines. Antibodies to a C-terminal peptide (residues 521-536) were developed which efficiently immunoprecipitate the 105 kDa IFNAR protein from detergent extracts of human cells. We show that the IFNAR protein becomes tyrosine phosphorylated within 5 min after treatment of human myeloma U266 cells with IFN-alpha 2, IFN-alpha 8 or IFN-beta. The IFNAR chain interacts with both IFN-alpha 2 and IFN-beta, as demonstrated by cross-linking. Among elements involved in signal transduction by type I IFNs, the tyrosine kinase Tyk2 but not Jak1, and the ISGF3 transcription factor subunit Stat2 (p113) but not Stat1 (p91), are found associated with the IFNAR protein. After IFN-beta treatment for 5 min, a tyrosine-phosphorylated protein of approximately 95 kDa (beta-PTyr) is found bound to IFNAR, but can be dissociated by denaturation. The beta-PTyr protein is present on the cell surface, like IFNAR, as shown by extracellular biotin tagging. The ratio of beta-PTyr to IFNAR tyrosine phosphorylation is much higher with IFN-beta than with IFN-alpha 2 or 8. Both are IFN dependent and abrogated by a monoclonal antibody which blocks IFNAR action. The beta-PTyr component may represent an important difference in the action of IFN-beta as compared with IFN-alpha in their shared receptor system.
Assuntos
Interferon-alfa/farmacologia , Interferon beta/farmacologia , Proteínas de Membrana/metabolismo , Fosfoproteínas/metabolismo , Receptores de Interferon/metabolismo , Sequência de Aminoácidos , Proteínas de Ligação a DNA/metabolismo , Humanos , Fator Gênico 3 Estimulado por Interferon , Fator Gênico 3 Estimulado por Interferon, Subunidade gama , Janus Quinase 1 , Dados de Sequência Molecular , Mieloma Múltiplo/metabolismo , Fosforilação , Ligação Proteica , Proteínas Tirosina Quinases/metabolismo , Proteínas/metabolismo , Receptor de Interferon alfa e beta , Receptores de Interferon/classificação , Receptores de Interferon/efeitos dos fármacos , Transdução de Sinais , TYK2 Quinase , Fatores de Transcrição/metabolismo , Células Tumorais Cultivadas , Tirosina/metabolismoRESUMO
Transcripts of the human IFN alpha-receptor (IFNAR) gene, lacking the transmembrane (TM) domain were found in human myeloma U266S cells, in addition to the transmembranal IFNAR cDNA. Two different cDNAs encoding such soluble IFNAR forms were identified. Form 1 has a deletion causing a frameshift toward the end of the extracellular (EC) domain predicting a tail of 7 amino acids. Form 2 has two in-frame deletions and conserves most of the intracytoplasmatic domain of IFNAR. The transcripts for the two soluble forms are still found in U266R cells which have lost the transmembranal IFNAR transcript. Human cells seem to have independent mechanisms to synthesize soluble IFN receptors, which may act as competitors outside the cells or carry IFN-mediated functions inside the cell.
Assuntos
RNA Mensageiro/genética , Receptores de Interferon/genética , Processamento Alternativo , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , DNA , Humanos , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Receptor de Interferon alfa e beta , Deleção de Sequência , Solubilidade , Células Tumorais CultivadasRESUMO
Poly(A)-enriched virus-specific mRNAs (v-mRNA) are revealed in the subcellular fractions (nuclei, mitochondria, polyribosomes and cytosol) from chicken and hamster Rous sarcoma cells. The qualitative and quantitative differences in v-mRNA populations from permissive and non-permissive tumors are shown. The sedimentation analysis of v-mRNAs allowed to ascertain the presence of three molecular classes of v-mRNA in nuclei and cytoplasm of chicken Rous sarcoma cells (35S, 28S and 22S, and 35S, 26-28S and 20S, respectively). While two size classes (33S and 20S) are shown in hamster Rous sarcoma nuclei, only 24S v-mRNA is revealed in the cytoplasm of its tumor tissue. Thus, the oncovirus gene expression is restricted in the non-permissive tumor cells, unlike of the permissive chicken Rous sarcoma cells, both in the level of transcription, and in the processing and transfer v-mRNAs from nucleus to cytoplasm. The virus gene function peculiarities in the tumors of birds and mammals are discussed.
Assuntos
Vírus do Sarcoma Aviário/análise , Nucleotídeos/análise , RNA Mensageiro/análise , RNA Viral/análise , Animais , Vírus do Sarcoma Aviário/crescimento & desenvolvimento , Sequência de Bases , Transformação Celular Neoplásica , Transformação Celular Viral , Células Cultivadas , Galinhas , Cricetinae , Peso Molecular , Hibridização de Ácido Nucleico , Poli A/análise , Replicação ViralRESUMO
Non-producer hamster and virus-producing chicken Rous sarcoma cells contain a complete avian sarcoma virus (ASV)-provirus DNA (pro-DNA). Unlike this, in normal hamster liver DNA to ASV--specific sequences are absent. Moreover, the nuclear chicken Rous sarcoma and chick embryo cell (CEC) DNA preparations contain practically all endogenous chicken virus (ECV)-specific sequences, while the hamster tumor DNA was annealed with only more than half of the ECV-RNA sequences. Thus, the pro-DNA of permissive hosts contains so-called "sarcoma-specific", "common" and "endogenous--specific" nucleotide sequences. The "sarcoma-specific" and "common" sequences are present in the hamster sarcoma pro-DNA, only. Both the pro-DNA of permissive cells and the pro-DNA of non-permissive cells consist of moderately reiterated and unique sequences. The "common" regions of pro-DNA are localized, mainly, in the unique zone, while "sarcoma-specific" and "endogenous-specific" sequences of pro-DNA - in the moderately reiterated and unique zones. The pro-DNA organization of permissive and non-permissive hosts is discussed.
Assuntos
Vírus do Sarcoma Aviário/análise , DNA Viral/análise , Animais , Sequência de Bases , Cricetinae , Genes ViraisRESUMO
Proviral DNA from non-producer Rous sarcoma in Syrian hamster contains practically all the nucleotide sequences presented in 125I-labeled RNA from Rous sarcoma virus, Carr-Zilber strain. Virus-specific sequences consist of moderately reiterated and unique DNA regions. The amount of Rous sarcoma virus-specific provirus equivalents in hamster Rous sarcoma DNA is equal to 5.2 +/- 0.01. Experiments on transfection show that proviral DNA studied possesses biological activity in respect to cell transformation and virus production. The infectivity of DNA from hamster tumor does not depend on the expression of group-specific (gs) antigen in the recipient cells.
Assuntos
DNA de Neoplasias/metabolismo , DNA Viral/metabolismo , Sarcoma Aviário/metabolismo , Animais , Vírus do Sarcoma Aviário/genética , Vírus do Sarcoma Aviário/crescimento & desenvolvimento , Vírus do Sarcoma Aviário/metabolismo , Sequência de Bases , Transformação Celular Neoplásica , Células Cultivadas , Cricetinae , DNA/genética , Mesocricetus , Hibridização de Ácido Nucleico , RNA Viral/metabolismo , TransfecçãoRESUMO
The distribution of poly(A)-enriched mRNA in nuclei, mitochondira, free and membrane-bound polyribosomes from normal C3HA mouse and Syrian hamster livers and normal chicken fibroblasts has been compared with that in corresponding subcellular fractions in a transplantable, chemically induced MD hepatoma, non-virus-producer hamster and virus-producer chicken Rous sarcomas. It has been shown that the content of poly(A)-RNA is increased in all tumour fractions except in free polyribosomes. The distribution of different classes of polysomes i.e. free, membrane-bound and mitochondrial outer-membrane-associated polysomes in tumour cells was changed in comparison to that in normal cells. It is concluded that in tumours of chemical and viral origin, the observed changes in the two components of the protein-synthesizing apparatus occur simultaneously.
Assuntos
Neoplasias Experimentais/metabolismo , Polirribossomos/metabolismo , RNA Mensageiro/metabolismo , RNA Neoplásico/metabolismo , Animais , Membrana Celular/metabolismo , Núcleo Celular/metabolismo , Cricetinae , Masculino , Camundongos , Mitocôndrias/metabolismoRESUMO
The hybridization properties of in vivo labeled nuclear and mitochondrial ribonucleic acids of an transplantable hepatoma were studied. It was shown that during tumor progression the repression of nuclear genome revelead at its early stages was replaced by the de-repression at its later stages. The hybridizability of mitochondrial RNA with nuclear DNA was not changed.
Assuntos
Carcinoma Hepatocelular/metabolismo , DNA de Neoplasias/metabolismo , Neoplasias Experimentais/metabolismo , RNA Neoplásico/metabolismo , Animais , Carcinoma Hepatocelular/induzido quimicamente , DNA Mitocondrial/metabolismo , Dietilnitrosamina , Neoplasias Hepáticas , Masculino , Camundongos , Camundongos Endogâmicos C3H , Neoplasias Experimentais/induzido quimicamente , Hibridização de Ácido Nucleico , Transcrição GênicaRESUMO
The content of poly(A)-containing RNA in subcellar fractions has been investigated both in cortisone-treated rat liver and experimental hepatoma cells. The fractions included nuclei, cytoplasm, mitochondria, free and membrane-bound polyribosomes. 1) In both cases of genome activation (cortisone induction and hepatoma cells) an increase in poly(A) content of all subcellular fractions except free polyribosomes was observed. 2) Cortisone was found to induce elongation of poly(A) segments detected in both nuclei and cytoplasm. 3) An increase in the poly(A) block size also was found to be stimulated in nuclei and cytoplasm of hepatoma cells. 4) The observed elongation in poly(A) length occurred against the background of an increase of the population of of poly(A)-RNA's.
Assuntos
Carcinoma Hepatocelular/metabolismo , Cortisona/farmacologia , Fígado/metabolismo , Poli A/metabolismo , RNA Mensageiro/metabolismo , RNA Neoplásico/metabolismo , Animais , Neoplasias Hepáticas , Camundongos , Neoplasias Experimentais/metabolismo , Ratos , Estimulação Química , Frações Subcelulares/metabolismoRESUMO
RNA--RNA molecular hybridization between [125I] RNA from Rous sarcoma virus virions and RNAs isolated from various subcellular fractions, i.e. nuclei, mitochondria, free and membrane-bound polyribosomes, from tumors induced by RSV in chickens resulted in the formation of RNAase-resistant hybrids only with the RNA of mitochondria and membrane-bound polysomes. The origin of complementary regions in the RNAs from these organelles is discussed.