RESUMO
C2 hydrocarbon separation from methane represents a technological challenge for natural gas upgrading. Herein, we report a new metal-organic framework, [Cu2L(DEF)2]·2DEF (UNT-14; H4L = 4,4',4â³,4â´-((1E,1'E,1â³E,1â´E)-benzene-1,2,4,5-tetrayltetrakis(ethene-2,1-diyl))tetrabenzoic acid; DEF = N,N-diethylformamide; UNT = University of North Texas). The linker design will potentially increase the surface area and adsorption energy owing to π(hydrocarbon)-π(linker)/M interactions, hence increasing C2 hydrocarbon/CH4 separation. Crystallographic data unravel an sql topology for UNT-14, whereby [Cu2(COO)4]···[L]4- paddle-wheel units afford two-dimensional porous sheets. Activated UNT-14a exhibits moderate porosity with an experimental Brunauer-Emmett-Teller (BET) surface area of 480 m2 g-1 (vs 1868 m2 g-1 from the crystallographic data). UNT-14a exhibits considerable C2 uptake capacity under ambient conditions vs CH4. GCMC simulations reveal higher isosteric heats of adsorption (Qst) and Henry's coefficients (KH) for UNT-14a vs related literature MOFs. Ideal adsorbed solution theory yields favorable adsorption selectivity of UNT-14a for equimolar C2Hn/CH4 gas mixtures, attaining 31.1, 11.9, and 14.8 for equimolar mixtures of C2H6/CH4, C2H4/CH4, and C2H2/CH4, respectively, manifesting efficient C2 hydrocarbon/CH4 separation. The highest C2 uptake and Qst being for ethane are also desirable technologically; it is attributed to the greatest number of "agostic" or other dispersion C-H bond interactions (6) vs 4/2/4 for ethylene/acetylene/methane.
RESUMO
Non-alcoholic fatty liver disease (NAFLD) is the most prevalent liver disease. Global Burden of Disease (GBD) data from 1990 to 2019 reported a rise in prevalence (9-13%) in Australia, which also ranked third highest for NAFLD prevalence compared to 14 similar countries. As a result of underdiagnosis, NAFLD burden is underestimated by GBD.
Assuntos
Carga Global da Doença , Hepatopatia Gordurosa não Alcoólica , Hepatopatia Gordurosa não Alcoólica/epidemiologia , Humanos , Austrália/epidemiologia , Prevalência , Masculino , Feminino , Efeitos Psicossociais da Doença , Pessoa de Meia-Idade , AdultoRESUMO
A healthy patient presented to Klinikum Altmühlfranken Weißenburg Hospital, Germany, with two morning attacks of painful muscle spasm in the left upper and lower limbs, without altered consciousness. Full examinations, radiological imaging, electroencephalography, lumbar puncture, and autoimmune profile were either normal or not consistent with patient's complaint. Subsequent epileptic episodes were observed on admission day and the following days; thus, the patient was diagnosed with focal epilepsy. The patient started to develop a fever and severe cough on day 4, and SARS-coronavirus-2 was confirmed through a nasopharyngeal swap. She received anticonvulsants and symptomatic treatments and completely recovered. This report emphasizes the potential nervous system involvement in severe acute respiratory syndrome-coronavirus-2 pathogenesis.
Assuntos
COVID-19/complicações , Epilepsias Parciais/complicações , SARS-CoV-2/patogenicidade , Acetaminofen/uso terapêutico , Acetilcisteína/uso terapêutico , Idoso , Ambroxol/uso terapêutico , Anticonvulsivantes/uso terapêutico , COVID-19/diagnóstico por imagem , COVID-19/virologia , Tosse/diagnóstico , Tosse/fisiopatologia , Dipirona/uso terapêutico , Epilepsias Parciais/diagnóstico por imagem , Epilepsias Parciais/tratamento farmacológico , Epilepsias Parciais/virologia , Feminino , Febre/diagnóstico , Febre/fisiopatologia , Humanos , Nasofaringe/virologia , Radiografia Abdominal , Resultado do Tratamento , Tratamento Farmacológico da COVID-19RESUMO
Till the day the rectal cancer deaths in the world is in eighth position. For rectal cancer surgery, short-term benefits are expected to be similar for laparoscopic resection of rectum (LRR) and open resection of rectum (ORR). In Bangladesh though the rectal cancer is the sixteenth most common cause of cancer deaths, there is lack of data regarding outcomes of laparoscopic and open surgical approaches for carcinoma rectum. Purpose of study was to compare oncopathological outcomes by quality of surgical resection between LRR and ORR groups. The quasi experimental study was conducted among 46 subjects who attended in the Department of Colorectal Surgery, Bangabandhu Sheikh Mujib Medical University, Bangladesh from July 2020 to June 2021 with rectal adenocarcinoma within 15cm from the anal verge. Equal number of subjects were allocated for LRR and ORR group. Oncopathological end points such as circumferential resection margin (CRM), distal resection margin (DRM), lymph nodes and quality of mesorectal excision were assessed and compared. Here every patients have given their written consent for this study. Mean age of the subjects for LRR and ORR were 45.47±12.66 and 44.47±12.48 years respectively. Majority of the subjects were in age above 40 years (67.0%). The proportion of male (56.5%) were higher than those of female (43.5%). The complete resection was better in LRR (91.3%) than ORR (87.0%) group though statistically not significant. CRM was lower in LRR (0.0%) than ORR (13.0%) group in respect of frequency distribution. DRM was negative for both LRR and ORR group (95.7% each) and it was not statistically significant. ORR met the National Comprehensive Cancer Network (NCCN) criteria of harvesting 12 lymph nodes were as in LRR group 10 lymph nodes were harvested. The mean harvested lymph nodes were 12.2±5.55 and 10.1±5.55 in LRR and ORR group respectively. The study demonstrated that LRR is better (though statistically not significant) in respect of complete resection and CRM while in harvesting lymph nodes, ORR met the NCCN criteria but LRR does not. There is no difference observed regarding DRM in both groups. On oncopathological point of view both the group showed almost equally effective results. Laparoscopic surgery can be opted as the standard operative technique for surgical management of rectal cancer.
Assuntos
Carcinoma , Laparoscopia , Neoplasias Retais , Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Reto/cirurgia , Margens de Excisão , Resultado do Tratamento , Laparoscopia/métodos , Neoplasias Retais/cirurgia , Neoplasias Retais/patologia , Carcinoma/patologiaRESUMO
Gadd45a-null mice generated by gene targeting exhibited several of the phenotypes characteristic of p53-deficient mice, including genomic instability, increased radiation carcinogenesis and a low frequency of exencephaly. Genomic instability was exemplified by aneuploidy, chromosome aberrations, gene amplification and centrosome amplification, and was accompanied by abnormalities in mitosis, cytokinesis and growth control. Unequal segregation of chromosomes due to multiple spindle poles during mitosis occurred in several Gadd45a -/- cell lineages and may contribute to the aneuploidy. Our results indicate that Gadd45a is one component of the p53 pathway that contributes to the maintenance of genomic stability.
Assuntos
Proteínas/genética , Animais , Apoptose/genética , Ciclo Celular/genética , Ciclo Celular/fisiologia , Divisão Celular/genética , Transformação Celular Neoplásica/genética , Senescência Celular , Centrossomo/metabolismo , Embrião de Mamíferos/citologia , Feminino , Fibroblastos/citologia , Fibroblastos/fisiologia , Fase G1 , Raios gama/efeitos adversos , Deleção de Genes , Genes ras/genética , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neoplasias/etiologia , Neoplasias/genética , Fenótipo , Proteínas/fisiologia , Hiperplasia do Timo/genética , Hiperplasia do Timo/patologia , Proteínas GADD45RESUMO
The necessity of a protective ileostomy in patients subjected to low anterior resection for rectal cancer has been discussed controversially. This prospective observational study was carried out to see the outcome of low anterior resection without a covering ileostomy. Forty patients underwent low anterior resection for primary rectal carcinoma in mid and distal rectum without any covering ileostomy from January 2007 and June 2010 in the department of Surgery of Bangabandhu Sheikh Mujib Medical University and two other private hospitals in Dhaka city. The primary objective of the study was to demonstrate clinical anastomotic leak rate, reoperation rate and morbidity and mortality related to leak. Thirty two male and eight female patients underwent low anterior resection for primary rectal carcinoma. Median age was 53 years (range 23-67). Majority of the tumors were located within 10cm from anal verge and most of the cases were in Duke's stage B and C. One male patient (overall 2.5%) developed clinical anastomotic leakage, but responded well to conservative treatment. There was no 30 days mortality. Covering ileostomy can be avoided in selected patients with low anterior resection for primary carcinoma in mid and distal rectum.
Assuntos
Adenocarcinoma/cirurgia , Canal Anal/cirurgia , Ileostomia/métodos , Neoplasias Retais/cirurgia , Adenocarcinoma/patologia , Adulto , Idoso , Canal Anal/patologia , Comorbidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/prevenção & controle , Estudos Prospectivos , Neoplasias Retais/patologia , Resultado do TratamentoRESUMO
We measured net calcium absorption and the calcium content of the digestive glands secretions in people with widely different serum concentrations of 1,25 dihydroxy vitamin D (hereafter referred to a 1,25-D). Patients with end stage renal disease on hemodialysis served as a model of human 1,25-D deficiency; they were also studied when they had abnormally high serum 1,25-D concentrations as a result of short periods of treatment with exogenous 1,25-D. Normal subjects were studied for comparison. The amount of calcium secreted into the duodenum by the digestive glands was found to be trivial compared to the calcium content of normal or even low calcium meals; therefore, values for net and true net calcium absorption differed only slightly. There was a linear correlation between true net calcium absorption and serum 1,25-D concentration. By extrapolating the short distance to a zero value for serum 1,25-D, D-independent true net calcium absorption was estimated. By subtracting D independent from true net calcium absorption, values for D-dependent absorption were obtained. For a given level of meal calcium intake, D-dependent calcium absorption was found to be directly proportional to serum 1,25-D concentration. At any given value for serum 1,25-D, absorption via the D-dependent mechanism was approximately the same with a low (120 mg) calcium meal as it was when meal calcium intake was increased to 300 mg. We interpret this to mean that the D-dependent mechanism is saturated or nearly saturated by low calcium meals. The D-independent absorption/secretion mechanism resulted in secretion (a loss of body calcium in the feces) when intake was low (120 mg per meal) and absorption when intake was normal. All of the increment in calcium absorption that occurs when low or normal calcium meals are supplemented with extra calcium is mediated by the D-independent mechanism.
Assuntos
Cálcio da Dieta/metabolismo , Absorção Intestinal , Vitamina D/fisiologia , Adulto , Calcitriol/sangue , Cálcio da Dieta/administração & dosagem , Duodeno/análise , Humanos , Falência Renal Crônica/metabolismo , Falência Renal Crônica/fisiopatologia , Diálise Renal , Vitamina D/sangueRESUMO
Antacids used to decrease phosphorus absorption in patients with renal failure may be toxic. To find more efficient or less toxic binders, a three-part study was conducted. First, theoretical calculations showed that phosphorus binding occurs in the following order of avidity: Al3+ greater than H+ greater than Ca2+ greater than Mg2+. In the presence of acid (as in the stomach), aluminum can therefore bind phosphorus better than calcium or magnesium. Second, in vitro studies showed that the time required to reach equilibrium varied from 10 min to 3 wk among different compounds, depending upon solubility in acid and neutral solutions. Third, the relative order of effectiveness of binders in vivo was accurately predicted from theoretical and in vitro results; specifically, calcium acetate and aluminum carbonate gel were superior to calcium carbonate or calcium citrate in inhibiting dietary phosphorus absorption in normal subjects. We concluded that: (a) inhibition of phosphorus absorption by binders involves a complex interplay between chemical reactions and ion transport processes in the stomach and small intestine; (b) theoretical and in vitro studies can identify potentially better in vivo phosphorus binders; and (c) calcium acetate, not previously used for medical purposes, is approximately as efficient as aluminum carbonate gel and more efficient as a phosphorus binder than other currently used calcium salts.
Assuntos
Dieta , Absorção Intestinal , Fósforo/farmacocinética , Acetatos/metabolismo , Ácido Acético , Adulto , Alumínio/metabolismo , Carbonato de Cálcio/metabolismo , Citratos/metabolismo , Ácido Cítrico , Humanos , Falência Renal Crônica/metabolismo , Cinética , Valores de ReferênciaRESUMO
Meticulous observance of standard infection control precautions by health care providers is strongly recommended for every patient encounter. Assessment of nursing students' compliance should be carried out regularly in order to ensure adherence to protocols. Thus, this study was conducted to assess self-reported compliance with standard precautions among baccalaureates in nursing students in a Saudi university. A convenience sample of 236 nursing students was surveyed in this cross-sectional, self-reported study, using the Compliance with Standard Precaution Scale Arabic version (CSPS-A). Independent t-test and one-way analyses of variance (ANOVA) were performed to examine the differences on compliance. A multiple regression analysis was performed to identify the factors affecting compliance. The overall compliance rate was 61.0%. The students reported highest compliance in disposing used sharp instruments and other sharp objects into sharps-only boxes, while the lowest compliance rate in using water only for hand washing. Significant differences in compliance were observed when respondents were grouped according to their demographic characteristics. Cultivating a supportive culture of adherence to infection control precautions among nursing students is of paramount importance. The clinical environment should be supportive of a culture where strict compliance with the control and prevention of infection is of prime importance.
Assuntos
Infecção Hospitalar/prevenção & controle , Fidelidade a Diretrizes , Ferimentos Penetrantes Produzidos por Agulha/prevenção & controle , Estudantes de Enfermagem , Adulto , Estudos Transversais , Feminino , Humanos , Masculino , Arábia Saudita , Autorrelato , UniversidadesRESUMO
PUMA, a key mediator of p53-induced apoptosis, is a BH3-only domain proapoptotic protein that localizes to mitochondria and interacts with antiapoptotic Bcl-2 and Bcl-X(L). Recent evidence implicates Bax to be an important mediator of PUMA-activated apoptotic signals. We have previously demonstrated that Bax deficiency significantly affects thapsigargin (TG)-mediated endoplasmic reticulum calcium pool depletion-induced apoptosis. We now present evidence that TG upregulates PUMA expression and that although Bax-deficient cells exhibit resistance to TG, Bax deficiency does not attenuate TG upregulation of PUMA expression. Furthermore, TG transcriptionally upregulates PUMA expression in a p53-independent manner and that PUMA-deficient cells are more resistant to undergo TG-induced apoptosis than the PUMA-proficient counterparts. Thus, our results demonstrate that TG engages PUMA and Bax for full transduction of apoptotic signals and both PUMA and Bax appear to exist in the same TG-activated apoptotic pathway in which PUMA may reside upstream of Bax.
Assuntos
Apoptose/fisiologia , Cálcio/metabolismo , Retículo Endoplasmático/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Apoptose/efeitos dos fármacos , Apoptose/efeitos da radiação , Proteínas Reguladoras de Apoptose , Sequência de Bases , Cálcio/deficiência , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/deficiência , Proteínas de Ligação a DNA/metabolismo , Genes Supressores de Tumor , Células HCT116 , Humanos , Masculino , Dados de Sequência Molecular , Proteínas Nucleares/deficiência , Proteínas Nucleares/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/deficiência , Tapsigargina/farmacologia , Transcrição Gênica/efeitos dos fármacos , Proteína Tumoral p73 , Proteínas Supressoras de Tumor , Regulação para Cima/efeitos dos fármacos , Proteína X Associada a bcl-2RESUMO
The biologically active synthetic retinoid CD437 (6-[3-adamantyl-4-hydroxyphenyl]-2-naphthalene, AHPN) and different human breast carcinoma (HBC) cell lines were used to examine the possible mechanism(s) of gadd45 induction. Northern blot analysis of mRNA isolated from MCF-7, MDA-MB-468 and MDA-MB-231 HBC cell lines demonstrated a progressive increase in the 1.4 kb gadd45 transcript after exposure to 1 microM CD437. Western blot analysis showed increased gadd45 protein levels in MDA-MB-468 HBC cells following exposure to CD437. CD437 increased gadd45 mRNA levels by approximately 20-fold in MDA-MB-468 cells, however, the transcriptional activity was increased approximately 2-3-fold as demonstrated by the human gadd45 promoter-luciferase reporter construct and nuclear run-off assays. Sublines of MDA-MB-468 HBC cells expressing stably integrated GADD45 cDNA fragments were obtained and CD437-dependent induction of GADD45 analyzed. We report that approximately 300 nt located in the 5"-untranslated region (5"-UTR) of gadd45 mRNA are involved in the CD437-dependent 4-fold enhanced stability of gadd45 transcripts. MDA-MB-468 cells were stably transfected with either a plasmid having a CMV promoter-driven rabbit beta-globin gene or plasmids having a CMV promoter-driven chimeric gadd45 5"-UTR-rabbit beta-globin gene, where the entire gadd45 5"-UTR (from +1 to +298) or a 45 bp subfragment of the gadd45 5"-UTR (from +10 to +55) was positioned at the 5"-end of the rabbit beta-globin gene. CD437 was found to up-regulate expression of both the chimeric gadd45 -rabbit beta-globin transcripts, suggesting that cis element(s) involved in the CD437-dependent enhanced stability of gadd45 mRNA are contained in the 45 nt of the 5"-UTR of the gadd45 mRNA.
Assuntos
Antineoplásicos/farmacologia , Neoplasias da Mama/genética , Dano ao DNA , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Proteínas/genética , Retinoides/farmacologia , Regiões 5' não Traduzidas/genética , Animais , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Dano ao DNA/genética , Globinas/genética , Globinas/metabolismo , Meia-Vida , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Mutação , Regiões Promotoras Genéticas/genética , Proteínas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Coelhos , Proteínas Recombinantes de Fusão/genética , Fatores de Tempo , Transcrição Gênica/efeitos dos fármacos , Transcrição Gênica/genética , Transfecção , Células Tumorais Cultivadas , Regulação para Cima/efeitos dos fármacos , Proteínas GADD45RESUMO
The human p53-binding protein murine double minute 2 (MDM2) is believed to function as a negative regulator of p53. The MDM2 gene was cloned and sequenced only recently and was found to be amplified in a variety of sarcomas. Although mutations in the p53 gene have been shown to occur in human breast carcinoma (HBC), no information is available on MDM2 gene expression in HBC. In this study we report for the first time that the MDM2 gene is differentially expressed in HBC. Our results demonstrate a correlation between the estrogen receptor (ER) status and the MDM2 mRNA levels. In contrast to the ER-negative cell lines, all the ER-positive cell lines were found to express higher levels of MDM2 mRNA. ER-positive ZR-75 cells express 30-fold higher levels of MDM2 mRNA than does the ER-negative cell line Hs578T. Estrogen enhanced albeit modestly the MDM2 mRNA levels in ER-positive MCF-7 cells. Estrogen enhancement of MDM2 mRNA levels was also observed in ER-negative MDA-MB-231 cells transfected with functional ERs. Our data thus suggest that estrogen may play an important role in HBC growth stimulation by modulating the expression of MDM2, which in turn may inactivate the p53 function.
Assuntos
Neoplasias da Mama/química , Proteínas de Neoplasias/análise , Proteínas Nucleares , Proteínas Proto-Oncogênicas , RNA Mensageiro/análise , RNA Neoplásico/análise , Receptores de Estrogênio/análise , Neoplasias da Mama/genética , Estradiol/farmacologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Genes p53/efeitos dos fármacos , Humanos , Proteínas de Neoplasias/genética , Proteínas Proto-Oncogênicas c-mdm2 , Transfecção , Células Tumorais CultivadasRESUMO
Sulindac is the most extensively investigated clinically relevant chemopreventive nonsteroidal anti-inflammatory drug. Sulindac sulfide is one of the major metabolites of sulindac that is believed to mediate its antitumorigenic effects by inducing apoptosis. Recent evidence suggests that sulindac sulfide engages the mitochondrial pathway involving caspase 9 and Bax to mediate its apoptotic effects [Zhang et al., Science (Wash. DC), 290: 989-992, 2000]. In this report, we demonstrate that sulindac sulfide also engaged the membrane death receptor (DR) pathway to mediate apoptosis. Sulindac sulfide up-regulated DR5 and activated the proximal caspase 8 in various different colon and prostate cancer cell lines. Sulindac sulfide specifically up-regulated the DR5 levels but had no effect on the levels of other DRs including DR4, Fas, and tumor necrosis factor receptor 1. To further delineate the role of DR5 in sulindac sulfide-induced apoptosis, we used JCA-1 prostate cancer cells that are deficient in mounting a Fas and tumor necrosis factor receptor 1-dependent apoptotic response but are proficient in mediating DR5-dependent apoptosis. JCA-1 cells were stably transfected with dominant-negative Fas-associated death domain to block the flow of apoptotic signals originating from the endogenous DR5, and sulindac sulfide-induced apoptosis was investigated. Our results indicated that by blocking the DR5-dependent apoptotic pathway, dominant-negative Fas-associated death domain did indeed inhibit sulindac sulfide-induced apoptosis. Furthermore, exogenous tumor necrosis factor-related apoptosis-inducing ligand, the ligand for DR5, also potentiated sulindac sulfide-induced apoptosis in all of the cell lines tested, thereby further supporting the involvement of DR5 in sulindac sulfide-induced apoptosis. Thus, our results demonstrate that sulindac sulfide also engages the membrane DR pathway involving DR5 and proximal caspase 8 to induce apoptosis.
Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Caspases/fisiologia , Neoplasias do Colo/patologia , Neoplasias da Próstata/patologia , Receptores do Fator de Necrose Tumoral/fisiologia , Sulindaco/farmacologia , Anti-Inflamatórios não Esteroides/farmacologia , Apoptose/fisiologia , Caspase 8 , Caspase 9 , Caspases/metabolismo , Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/metabolismo , Ativação Enzimática , Células HT29 , Humanos , Masculino , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/metabolismo , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Receptores do Ligante Indutor de Apoptose Relacionado a TNF , Receptores do Fator de Necrose Tumoral/biossíntese , Receptores do Fator de Necrose Tumoral/genética , Sulindaco/análogos & derivados , Células Tumorais Cultivadas , Regulação para Cima/efeitos dos fármacosRESUMO
Insulin-like growth factors (IGF) I and II are potent mitogens for breast carcinoma proliferation. IGF-mediated proliferative activity can be markedly enhanced by the presence of specific IGF-binding proteins (IGFBPs). IGFBP-3 has been shown to enhance IGF-mediated growth in a number of systems. Studies have demonstrated IGFBP-3 secretion only in estrogen receptor (ER)-negative breast carcinoma cell lines while IGFBP-3 could not be detected in media conditioned by ER-positive cell lines. We investigated whether a relationship exists between ER status and IGFBP-3 mRNA expression in human breast carcinoma biopsy specimens. We have detected IGFBP-3 mRNA in breast carcinoma tissue obtained from patients utilizing in situ hybridization. Quantitation of IGFBP-3 mRNA levels was performed utilizing image cytometry. There was a significantly higher expression of IGFBP-3 mRNA in ER-negative breast carcinoma specimens when compared to the ER-positive specimens. Whether this higher expression of IGFBP-3 mRNA and presumed secretion of IGFBP-3 by ER-negative tumors play a role in the rapid proliferation and poor prognosis of these tumors remains to be determined.
Assuntos
Neoplasias da Mama/genética , Carcinoma/genética , Proteínas de Transporte/metabolismo , Receptores de Estrogênio/metabolismo , Expressão Gênica , Humanos , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina , Hibridização de Ácido Nucleico , RNA Mensageiro/genética , Receptores de Progesterona/metabolismo , Fase S , Somatomedinas/metabolismoRESUMO
Estrogen receptor (ER)-positive human breast carcinoma (HBC) cell lines express significantly higher levels of retinoic acid receptor alpha (RAR alpha) (isoform 1) mRNA than ER-negative HBCs. Estradiol enhances RAR alpha mRNA expression in different ER-positive HBCs by 2-3-fold, which in turn results in increased sensitivity of ER-positive HBCs to the growth inhibitory effects of retinoic acid. To investigate the regulatory mechanisms of estradiol-mediated enhancement of RAR alpha mRNA expression, the functional promoter for the human RAR alpha isoform 1 was cloned and used to assess estradiol-mediated promoter-dependent enhancement of firefly luciferase reporter gene activity in transiently transfected ER-positive (MCF-7 and T47D) and ER-negative (MDA-MB-231) HBCs. Deletional promoter constructs were obtained to further delineate the promoter region responsible for estradiol-mediated enhancement of promoter activity. Here, we present evidence that approximately 130 bp of the promoter fragment preceding the transcriptional start site are responsible for estradiol-mediated enhancement of hRAR alpha gene expression. The estradiol-mediated enhancement is dependent on ER binding. Further deletional analysis showed that a promoter sequence of 42 base pairs, located approximately 100 bases upstream of the transcriptional start site, contains elements for estradiol-mediated enhancement. Specific deletion of either the Sp1 motif or mutations in the imperfect half-palindromic estrogen response element motif of this fragment abolish its estradiol responsiveness in transient transfections.
Assuntos
Neoplasias da Mama/genética , Estradiol/farmacologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Regiões Promotoras Genéticas/genética , Receptores de Estrogênio/genética , Receptores do Ácido Retinoico/genética , Fator de Transcrição Sp1/genética , Sequência de Bases , Neoplasias da Mama/ultraestrutura , Clonagem Molecular , DNA Complementar/genética , DNA Complementar/isolamento & purificação , Genes Reporter , Humanos , Luciferases/genética , Luciferases/metabolismo , Dados de Sequência Molecular , Receptores de Estrogênio/metabolismo , Receptor alfa de Ácido Retinoico , Transfecção , Células Tumorais CultivadasRESUMO
The death receptor (DR) KILLER/DR5 gene has recently been identified as a doxorubicin-regulated transcript that was also induced by exogenous wild-type p53 in p53-negative cells. KILLER/DR5 gene encodes a DR containing cell surface protein that is highly homologous to DR4, another DR of the tumor necrosis factor (TNF) receptor family. Both DR4 and KILLER/DR5 independently bind to their specific ligand TRAIL and engage the caspase cascade to induce apoptosis. TRID (also known as TRAIL-R3) is an antiapoptotic decoy receptor that lacks the cytoplasmic death domain and competes with KILLER/DR5 and DR4 for binding to TRAIL. In this study, we demonstrate that the DR KILLER/DR5 gene is regulated in a p53-dependent and -independent manner during genotoxic and nongenotoxic stress-induced apoptosis. Just like other p53-regulated genes, ionizing radiation induction of KILLER/DR5 occurs in p53 wild-type cells, whereas methyl methanesulfonate regulation of KILLER/DR5 occurs in a p53-dependent and -independent manner. However, unlike other p53-regulated genes, KILLER/DR5 is not regulated following UV irradiation. TNF-alpha, a nongenotoxic cytokine, also induced the expression of KILLER/DR5 in a number of cancer cell lines, irrespective of p53 status. TNF-alpha did not alter the KILLER/DR5 mRNA stability, suggesting that the TNF-alpha regulation of KILLER/DRS expression appears transcriptional. We also provide evidence that KILLER/DR5 is regulated in a trigger and cell type-specific manner and that its induction by TNF-alpha, p53, or DNA damage is not the consequence of apoptosis induced by these agents. Unlike KILLER/DR5, none of the other KILLER/DR5 family members, including DR4, TRID, or the ligand TRAIL, displayed genotoxic stress or TNF-alpha regulation in a p53 transcription-dependent manner. Thus, KILLER/DR5 appears a bona fide downstream target of p53 that is also regulated in a cell type-specific, trigger-dependent, and p53-independent manner.
Assuntos
Apoptose , Regulação Neoplásica da Expressão Gênica , Receptores do Fator de Necrose Tumoral/metabolismo , Fator de Necrose Tumoral alfa/farmacologia , Proteína Supressora de Tumor p53/fisiologia , Proteínas Reguladoras de Apoptose , Northern Blotting , Relação Dose-Resposta a Droga , Doxorrubicina/farmacologia , Proteínas Ligadas por GPI , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos da radiação , Humanos , Immunoblotting , Glicoproteínas de Membrana/metabolismo , Metanossulfonato de Metila/farmacologia , RNA Mensageiro/análise , Radiação Ionizante , Receptores do Ligante Indutor de Apoptose Relacionado a TNF , Membro 10c de Receptores do Fator de Necrose Tumoral , Ligante Indutor de Apoptose Relacionado a TNF , Fatores de Tempo , Transfecção , Células Tumorais Cultivadas/efeitos dos fármacos , Células Tumorais Cultivadas/efeitos da radiação , Receptores Chamariz do Fator de Necrose Tumoral , Fator de Necrose Tumoral alfa/metabolismo , Raios UltravioletaRESUMO
DNA-damaging agents such as ionizing radiation (IR) activate the tumor suppressor p53, and, in turn, p53 transactivates a number of downstream effector genes such as GADD45, CIP1/WAF1, and MDM2. The induction of these downstream genes following IR appears to be strictly dependent upon the presence of wild-type functional p53 known to evoke G1 arrest. In this study, we characterized 56 cell lines from 9 different tumor types with predetermined p53 genotype by measuring the induction of GADD45, CIP1/WAF1, and MDM2 relative mRNA levels after IR. A higher fraction of melanoma lines had wild-type (wt) p53 (5/8, or 63%) compared to the nonmelanoma lines (11/48, or 23%). Most wt p53 (nonmelanoma) cell lines (11/12, or 92%) showed clear induction of both GADD45 and CIP1/WAF1. On the other hand, many wt p53 melanoma lines (4/5, or 80%) showed normal induction of CIP1/WAF1, but little or no induction of GADD45. Despite this defect in GADD45 induction, we found that all wt p53 melanoma lines exhibited strong G1 arrest and increased levels of p53 protein after IR. The results demonstrated that radiation-induced G1 arrest could occur by the p53-CIP1/WAF1 pathway without appreciable induction of GADD45 in melanoma lines. Time course experiments demonstrated prolonged induced expression of CIP1/WAF1 mRNA transcripts in melanoma lines in which GADD45 induction was lacking, suggesting some sort of compensatory mechanism involving CIP1/WAF1, in cell lines with defective GADD45 induction. We could reproduce this compensatory effect in RKO colon carcinoma cells in which GADD45 expression was blocked by constitutive antisense vectors. These findings reveal that defective induction of GADD45 following IR is common in human melanoma cell lines.
Assuntos
Genes p53/efeitos da radiação , Proteínas Nucleares , Proteínas , Transcrição Gênica/efeitos da radiação , Sequência de Bases , Linhagem Celular , Inibidor de Quinase Dependente de Ciclina p21 , Ciclinas/biossíntese , Dano ao DNA , Primers do DNA , DNA de Neoplasias/biossíntese , DNA de Neoplasias/efeitos da radiação , Feminino , Citometria de Fluxo , Raios gama , Genótipo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Melanoma , Dados de Sequência Molecular , Proteínas de Neoplasias/biossíntese , Fases de Leitura Aberta , Reação em Cadeia da Polimerase , Biossíntese de Proteínas , Proteínas Proto-Oncogênicas/biossíntese , Proteínas Proto-Oncogênicas c-mdm2 , Ativação Transcricional/efeitos da radiação , Células Tumorais Cultivadas , Proteína Supressora de Tumor p53/biossíntese , Proteína Supressora de Tumor p53/efeitos da radiação , Proteínas GADD45RESUMO
Esophageal cancer-related gene 2 (ECRG2) is a newer tumor suppressor whose function in the regulation of cell growth and apoptosis remains to be elucidated. Here we show that ECRG2 expression was upregulated in response to DNA damage, and increased ECRG2 expression induced growth suppression in cancer cells but not in non-cancerous epithelial cells. ECRG2-mediated growth suppression was associated with activation of caspases and marked reduction in the levels of apoptosis inhibitor, X chromosome-linked inhibitor of apoptosis protein (XIAP). ECRG2, via RNA-binding protein human antigen R (HuR), regulated XIAP mRNA stability and expression. Furthermore, ECRG2 increased HuR ubiquitination and degradation but was unable to modulate the non-ubiquitinable mutant form of HuR. We also identified missense and frame-shift ECRG2 mutations in various human malignancies and noted that, unlike wild-type ECRG2, one cancer-derived ECRG2 mutant harboring glutamic acid instead of valine at position 30 (V30E) failed to induce cell death and activation of caspases. This naturally occurring V30E mutant also did not suppress XIAP and HuR. Importantly, the V30E mutant overexpressing cancer cells acquired resistance against multiple anticancer drugs, thus suggesting that ECRG2 mutations appear to have an important role in the acquisition of anticancer drug resistance in a subset of human malignancies.
Assuntos
Proteína Semelhante a ELAV 1/metabolismo , Proteínas Secretadas Inibidoras de Proteinases/metabolismo , Apoptose , Linhagem Celular Tumoral , Dano ao DNA , Resistencia a Medicamentos Antineoplásicos/genética , Humanos , Mutação , Proteínas Secretadas Inibidoras de Proteinases/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Inibidores de Serinopeptidase do Tipo Kazal , Ubiquitinação , Proteínas Inibidoras de Apoptose Ligadas ao Cromossomo X/genéticaRESUMO
Recent studies suggest that genotoxic and non-genotoxic stresses appear to invoke translational checkpoints in order to inhibit protein synthesis. Depending on the stress and/or cell type, this downregulation of protein synthesis may either (i) protect against the deleterious effects of noxious agents and ensure the conservation of resources that are needed to survive under adverse conditions or (ii) activate apoptosis. In this article, we have reviewed several lines of evidence which support the notion that regulation of translation initiation is an important component of the cellular stress response. While the stress-induced post-translational regulation of translation initiation factors (eIFs) has been well documented, stress-induced regulation of eIFs at the mRNA levels, as reviewed here, is only beginning to be elucidated. Thus, the stress-mediated regulation of eIFs occurs at multiple different levels involving, transcriptional, post-transcriptional and post-translational controls.
Assuntos
Regulação da Expressão Gênica , Fatores de Iniciação de Peptídeos/genética , Biossíntese de Proteínas/genética , Biossíntese de Proteínas/fisiologia , Sequência de Aminoácidos , Animais , Apoptose/fisiologia , Humanos , Dados de Sequência Molecular , Fatores de Iniciação de Peptídeos/metabolismo , Fosforilação , Processamento de Proteína Pós-Traducional , Transcrição Gênica/genéticaRESUMO
The p21WAF1/CIP1 protein was shown to be a critical downstream effector of p53 and a potent inhibitor of cyclin-dependent kinases. We investigated the effects of exogenous p21WAF1/CIP1 in two different human breast carcinoma (HBC) cell lines MCF-7 and T47D. p21WAF1/CIP1 transfected cells formed significantly reduced number of drug-resistant colonies than their mock-transfected counterparts. The majority of the p21WAF1/CIP1 transfected MCF-7 cells acquired 50-100-fold increase in their sizes and persisted as single giant cells for several days without cell division, while the remainder underwent nuclear division (multiple nuclei) but were unable to complete cytokinesis, and finally all succumbed to apoptosis. Only few p21WAF1/CIP1 transfected T47D cells displayed increase in their sizes while a number of them formed small sized drug-resistant colonies which diminished in size due to cell death. The cells in these shrinking colonies exhibited characteristic signs of apoptosis such as chromatin condensation and fragmented nuclei while their membrane integrity was preserved. Thus in HBC cell lines the growth suppression due to enforced overexpression of p21WAF1/CIP1 is associated with giant cell formation and apoptosis.