ABSTRACT
BACKGROUND@#The rs1520220 polymorphism in the insulin-like growth factor 1 (IGF1) gene has been reported to affect cancer susceptibly in several studies. However, the results of the relevant studies are inconsistent. We conduct a current meta-analysis to investigate the association between rs1520220 and cancer susceptibly.@*METHODS@#Three databases (PubMed, Embase, and Web of Science) were searched for studies regarding the relationship between rs1520220 and cancer susceptibly. Odds ratios (ORs) and the related 95% confidence intervals (CIs) were employed to assess the strength of the associations. A stratified analysis was performed according to cancer type, ethnicity, and quality score, and when results were obtained from no fewer than two studies, these results were pooled.@*RESULTS@#There was no positive association between rs1520220 and overall cancer risk. However, the analysis stratified by ethnicity revealed that rs1520220 significantly increased cancer susceptibility in Asian populations (allele model OR = 1.10, 95%Cl = 1.00-1.21, p = 0.040; homozygote model OR = 1.22, 95%Cl = 1.01-1.47, p = 0.040; dominant model OR = 1.19, 95%Cl = 1.01-1.39, p = 0.033). No significantly association was detected in Caucasian populations. The analysis stratified by cancer type suggested that rs1520220 was not associated with susceptibility to breast cancer.@*CONCLUSIONS@#The results of our meta-analysis demonstrate that the role of IGF1 rs1520220 in cancer susceptibility varies by ethnicity and cancer type and that rs1520220 increases cancer susceptibility in Asian populations.
Subject(s)
Humans , Asian People , Racial Groups , Gene Frequency , Genetic Predisposition to Disease , Insulin-Like Growth Factor I , Genetics , Neoplasms , Ethnology , Genetics , Odds Ratio , Polymorphism, Single NucleotideABSTRACT
<p><b>OBJECTIVE</b>To study the regulatory role of interferon-stimulated response elements (ISREs) located on the retinoic acid-induced gene G (RIG-G) promoter in RIG-G expression.</p><p><b>METHODS</b>By using point mutation technique, the authors constructed the wide type and site mutant reporter gene plasmids according to the ISRE sequence on RIG-G promoter, and detected the functional activities by luciferase reporter assay.</p><p><b>RESULTS</b>Mutation in ISRE II alone had no obvious effect on the expression of the reporter gene, whereas mutation in ISRE I dramatically inhibited the transactivity of RIG-G promoter. Mutation in both ISRE I and ISRE II resulted in complete loss of its response to the transcription factors for the reporter gene.</p><p><b>CONCLUSION</b>Both ISRE I and ISRE II on the RIG-G promoter are the binding sites for the complex of transcription factors. They are required for RIG-G expression, and ISRE I has a preferential role over ISRE II.</p>
Subject(s)
Humans , Cell Line, Tumor , Interferon Regulatory Factor-1 , Genetics , Metabolism , Interferons , Genetics , Metabolism , Intracellular Signaling Peptides and Proteins , Genetics , Mutation , Promoter Regions, Genetic , Genetics , Response Elements , Genetics , STAT2 Transcription Factor , Genetics , MetabolismABSTRACT
<p><b>OBJECTIVE</b>To investigate the molecular mechanisms by which IFN-alpha regulated retinoic acid-induced gene G (RIG-G) expression.</p><p><b>METHODS</b>The expression of STAT1, p-STAT1 and RIG-G in IFN-alpha-treated NB4 cells was detected by Western blot. The roles of STAT1, STAT2 and IRF-9 in IFN-alpha-induced RIG-G expression were analyzed in STAT1-null U3A cells by cell transfection, reporter gene assay, co-immunoprecipitation and chromatin immunoprecipitaion.</p><p><b>RESULTS</b>In U3A cells, only when STAT2 and IRF-9 were co-transfected, the luciferase activities of RIG-G promoter-containing reporter gene could be highly increased about 8-fold compared with that in the control group. Moreover, in the absence of IFN-alpha, similar effects were observed in either IRF-9 co-transfected with wild type or mutant form of STAT2, whereas IFN-alpha could increase the transactivation activity of wild type STAT2 and IRF-9 by 6-fold compared with that without IFN-alpha, but had no effect on mutant STAT2. In addition, STAT2 could interact with IRF-9 and bind to the RIG-G promoter.</p><p><b>CONCLUSION</b>STAT2 may interact with IRF-9 in a STAT1-independent manner. The complex STAT2/IRF-9 is the key factor mediating the expression of RIG-G gene regulated by IFN-alpha. This is a novel signal transduction cascade for IFN which is different from the classical JAK-STAT pathway.</p>
Subject(s)
Humans , Cell Line, Tumor , Fibrosarcoma , Metabolism , Pathology , Gene Expression Regulation, Neoplastic , Immunoprecipitation , Interferon-Stimulated Gene Factor 3, gamma Subunit , Genetics , Metabolism , Interferon-alpha , Pharmacology , Intracellular Signaling Peptides and Proteins , Genetics , Metabolism , Leukemia, Promyelocytic, Acute , Metabolism , Pathology , Phosphorylation , Plasmids , STAT1 Transcription Factor , Genetics , Metabolism , STAT2 Transcription Factor , Genetics , Metabolism , Signal Transduction , TransfectionABSTRACT
To investigate the molecular mechanisms of all-trans retinoic acid (ATRA)-induced rig-g gene expression and to better understand the signal transduction of ATRA during acute promyelocytic leukemia (APL) cell differentiation, the luciferase reporter assay, co-immunoprecipitation and chromatin immunoprecipitation were used to clarify the basic transcriptional factors, which directly initiated the expression of rig-g gene. The results showed that the expression of STAT2, IRF-9 and IRF-1 could be upregulated by ATRA with different kinetics in NB4 cells. IRF-9 was able to interact with STAT2 to form a complex, which could bind the rig-g gene promoter and trigger the rig-g expression. IRF-1 alone could also activate the reporter gene containing rig-g gene promoter, but C/EBPalpha could strongly inhibit this transcription activity of IRF-1. It is concluded that during ATRA-induced APL cell differentiation, IRF-1 is first upregulated by ATRA, and then IRF-1 increases the protein levels of IRF-9 and STAT2 with the downregulation of C/EBPalpha. The complex of IRF-9 and STAT2 is the primary transcriptional factor for rig-g gene induction. This study will be helpful for better understanding the signal transduction networks of ATRA during the course of APL cell differentiation.
Subject(s)
Humans , CCAAT-Enhancer-Binding Protein-alpha , Metabolism , Gene Expression Regulation, Leukemic , Genes, Regulator , Interferon Regulatory Factor-1 , Metabolism , Interferon-Stimulated Gene Factor 3, gamma Subunit , Metabolism , Intracellular Signaling Peptides and Proteins , Genetics , Leukemia, Promyelocytic, Acute , Genetics , STAT2 Transcription Factor , Metabolism , Signal Transduction , Tretinoin , Pharmacology , Tumor Cells, CulturedABSTRACT
This study was purposed to investigate the expression of ifi56 gene in the ATRA-induced acute promyelocytic leukemia (APL) NB4 cell differentiation and to construct the eukaryotic expression plasmid of ifi56 gene. RT-PCR was used to detect the expression of ifi56 in NB4 cells treated with ATRA for different time. Human ifi56 cDNA was amplified by RT-PCR and cloned into pEGFP-C1 vector, then was transfected into 293T cells. The expression of the recombinant protein in 293T cells was detected by Western blot. The localization of IFI56 protein was observed by fluorescence microscopy. The results showed that the ifi56 mRNA was almost undetectable in untreated NB4 cells, but it significantly increased after ATRA treatment for 72 hours. The cDNA fragment of ifi56 was inserted into the expressing plasmid pEGFP-C1 successfully. The expression of EGFP-IFI56 fusion protein with a molecular weight about 83 kD was detected by Western blot. The EGFP-IFI56 protein was localized in cytoplasm mainly. It is concluded that the expression of ifi56 is enhanced significantly when the differentiation of APL cells was induced by ATRA. Gene ifi56 is successfully cloned into eukaryotic expression vector and the fusion protein is expressed in the cytoplasm mainly.