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Results for “RNA Stability”

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At least 721 records · Page 40Linked to original sources

PubMed2000

Cross-talk between fatty acid and cholesterol metabolism mediated by liver X receptor-alpha.

LXR alpha (liver X receptor, also called RLD-1) is a nuclear receptor, highly expressed in tissues that play a role in lipid homeostasis. In this report we show that fatty acids are positive regulators of LXR alpha gene expression and we investigate the molecular mechanisms underlying this regulation. In cultured rat hepatoma and primary hepatocyte cells, fatty acids and the sulfur-substituted fatty acid analog, tetradecylthioacetic acid, robustly induce LXR alpha (up to 3.5- and 7-fold, respectively) but not LXR beta (also called OR-1) mRNA steady state levels, with unsaturated fatty acids being more effective than saturated fatty acids. RNA stability and nuclear run-on studies demonstrate that changes in the transcription rate of the LXR alpha gene account for the major part of the induction of LXR alpha mRNA levels. A similar induction of protein level was also seen after treatment of primary hepatocytes with the same fatty acids. Consistent with such a transcriptional effect, transient transfection studies with a luciferase reporter gene, driven by 1.5 kb of the 5'-flanking region of the mouse (m)LXR alpha gene, show a peroxisome proliferator-activated receptor-alpha-dependent increase in luciferase activity upon treatment with tetradecylthioacetic acid and the synthetic peroxisome proliferator-activated receptor-alpha activator, Wy 14.643, suggesting that the mLXR alpha 5'-flanking region contains the necessary sequence elements for fatty acid responsiveness. In addition, in vivo LXR alpha expression was induced by fatty acids, consistent with the in vitro cell culture data. These observations demonstrate that LXR alpha expression is controlled by fatty acid signaling pathways and suggest an important cross-talk between fatty acid and cholesterol regulation of lipid metabolism.

Animals↗

PubMed2000

A novel mechanism of retinoic acid-enhanced interleukin-8 gene expression in airway epithelium.

A 3- to 8-fold stimulation of interleukin (IL)-8 gene expression by all-trans-retinoic acid (ATRA) was demonstrated in primary cultures of human and monkey tracheobronchial epithelial cells and BEAS-2B serum-sensitive cell line. The effect of ATRA on IL-8 gene expression is dose- and time-dependent. Using cycloheximide, it was observed that new protein synthesis was required for the stimulation. ATRA had no effect on IL-8 messenger RNA stability. A difference in nuclear run-on activity suggests that a transcriptional mechanism is involved in ATRA-enhanced IL-8 gene expression. Promoter-reporter gene transfection studies demonstrated ATRA enhanced IL-8 promoter activity, especially when cells were cotransfected with retinoic acid nuclear receptor-alpha expression vector. Deletion and site-directed mutagenesis analysis revealed the involvement of nuclear factor (NF)-kappaB binding site of the IL-8 gene in ATRA-enhanced promoter activity. Electrophoretic mobility shift assay (EMSA) demonstrated that ATRA enhanced DNA-NF-kappaB complex formation, especially with the p65 subunit. Western blot analysis demonstrated that ATRA did not enhance the protein amount of both the p50 and the p65 subunits in the nuclei. Because ATRA also enhances thioredoxin (TRX) gene expression, the effect of TRX on IL-8 gene expression was examined. IL-8 promoter activity was enhanced in transfected cells by the addition of TRX protein. Treatment of nuclear extracts with TRX also enhanced DNA- NF-kappaB complex formation as observed by EMSA, particularly the p65 subunit. Taking these data together, a novel mechanism is proposed in which ATRA activates promoter activity of IL-8 gene through TRX-dependent NF-kappaB activation.

Animals↗

PubMed1995

Evidence for altered regulation of gamma-glutamylcysteine synthetase gene expression among cisplatin-sensitive and cisplatin-resistant human ovarian cancer cell lines.

We have shown previously that tumor cell resistance to cisplatin is associated with elevated intracellular levels of glutathione, which is accomplished at least in part by increased expression of the heavy subunit of gamma-glutamylcysteine synthetase (gamma-GCS). To investigate the mechanism by which gamma-GCS expression is elevated, we have examined four related human ovarian cancer cell lines with increasing cisplatin resistance. Relative amounts of steady-state gamma-GCS mRNA in CP70, C30, and C200 were 4.8, 6.0, and 10.6, respectively, compared to the parental A2780 cell line, and a proportional increase in the transcriptional rate but not RNA stability was demonstrated. In contrast, no increase in mRNA for the gamma-GCS light subunit was found. To determine the mechanism of upregulation of this mRNA, we have cloned the promoter of the gene that encodes the heavy subunit of gamma-GCS. This region contains AP-1, NF-kappa B, XRE, AP-2, EpRE, CAAT, and TATA box elements upstream of the transcription initiation site and two MREs between this site and the start codon for the protein. Using gel mobility shift assays, we have found nuclear extract binding activity to the AP-1 response element to be closely associated with the level of gamma-GCS gene expression. A supershift assay showed that the AP-1 DNA-binding complexes are predominantly formed by dimers of JUN family members. Consistent with this finding, the expression of c-JUN was found to be elevated in the resistant cells. In contrast to AP-1 binding, AP-2 and NF-kappa B binding were inversely related to resistance. Furthermore, we have examined a partial revertant of the C200-resistant cells, which shows lower glutathione levels, and found decreased gamma-GCS expression associated with decreased AP-1 binding activity.

Antineoplastic Agents↗

PubMed1990

Human glucocorticoid receptor cDNA contains sequences sufficient for receptor down-regulation.

Glucocorticoid receptors are ligand-dependent transcription factors that are subject to down-regulation by their cognate ligand; however, the mechanisms mediating this physiological response are not completely understood. Since analysis of the human glucocorticoid receptor (hGR) cDNA sequence revealed the presence of sequences with homology to both positive and negative glucocorticoid regulatory elements, we have examined the potential of hGR to bind to the hGR cDNA by Southwestern blot analysis. The data revealed that glucocorticoid receptors exhibited specific binding to their own cDNA. To determine whether this binding was of functional significance in the down-regulation of glucocorticoid receptors, we analyzed the effect of glucocorticoids on hGR protein levels from COS 1 cells transfected with an hGR cDNA expression vector. These transfected cells produced intact hGR that were capable of ligand-dependent regulation of a co-transfected glucocorticoid-responsive reporter gene. Glucocorticoid treatment of hGR-transfected cells resulted in down-regulation of hGR (assayed by both glucocorticoid binding capacity and hGR protein levels) within 24 h of steroid administration. To determine if the glucocorticoid-induced down-regulation of transfected hGR was compatible with effects at the levels of receptor gene expression and RNA stability, we examined hGR mRNA steady state levels. Reductions from 2- to 6-fold were observed in hGR mRNA levels following glucocorticoid treatment of transfected COS 1 cells. This down-regulation of transfected hGR mRNA could not be attributed to either the Rous sarcoma virus promoter, which drives hGR expression, or to other sequences present in the vector plasmid since transcription of a related plasmid containing a chloramphenicol acetyltransferase gene in place of the hGR cDNA was not regulated by glucocorticoids. Down-regulation of hGR mRNA by glucocorticoids in transfected cells occurred in a time- and dose-dependent manner that is consistent with a glucocorticoid receptor-mediated process. Glucocorticoid-induced down-regulation of hGR mRNa steady state levels was not observed in COS 1 cells transfected with cDNAs encoding mutant hGR (defective in either steroid or DNA binding), which indicates that functional steroid and DNA binding domains of the expressed hGR were required for down-regulation. Interestingly, treatment of transfected COS 1 cells with the glucocorticoid antagonist RU486 also resulted in down-regulation of transfected hGR mRNA. Deletion analysis revealed that the region of the hGR cDNA that was responsible in part for the observed down-regulation in response to glucocorticoid was contained within a 1-kilobase restriction fragment (from base pair +527 to +1526).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1999

Altering the 3 UTR endonucleolytic cleavage site of a Chlamydomonas chloroplast mRNA affects 3-end maturation in vitro but not in vivo.

The 3' ends of chloroplast mRNAs are produced by the processing of longer precursors. The 3' ends of most plastid mRNAs are located at, or several nucleotides downstream of, stem-loop structures, which act as 3'-end-processing signals and RNA stability elements. In chloroplasts of the green alga Chlamydomonas reinhardtii, 3'-end maturation of atpB mRNA involves endonucleolytic cleavage of the pre-mRNA at an AU-rich site located about 10 nucleotides downstream of the stem-loop structure. This cleavage is followed by exonucleolytic resection to generate the mature 3' end. In order to define critical nucleotides of the endonucleolytic cleavage site, we mutated its sequence. Incubation of synthetic atpB pre-RNAs containing these mutations in a chloroplast protein extract resulted in the accumulation of 3'-end-processed products. However, in two cases where the AU-rich sequence of this site was replaced with a GC-rich one, the 3' end of the stable processing product differed from that of the wild-type product. To examine whether these mutations affected atpB mRNA processing or accumulation in vivo, the endogenous 3' UTR was replaced with mutated sequences by biolistic transformation of Chlamydomonas chloroplasts. Analysis of the resulting strains revealed that the accumulation of atpB mRNA was approximately equal to that of wild-type cells, and that a wild-type atpB 3' end was generated. These results imply that Chlamydomonas atpB 3' processing parallels the situation with other endonucleases such as Escherichia coli RNAse E, where specific sequences are required for correct in vitro processing, but in vivo these mutations can be overcome.

3' Untranslated Regions↗

PubMed2000

Cycloheximide increases proenkephalin and tyrosine hydroxylase gene expression in rat adrenal medulla.

The effect of cycloheximide (CHX; 5 mg/kg) on proenkephalin (proENK) and tyrosine hydroxylase (TH) mRNA expression in rat central and peripheral nervous systems was studied. CHX increased proENK and TH mRNA levels in the adrenal gland, but not in hippocampus, striatum, midbrain, brainstem, pituitary, and hypothalamus. The pretreatment with actinomycin D (0.5 mg/kg) significantly decreased CHX-induced proENK and TH mRNA expression, suggesting that the CHX-dependent increase of these mRNA levels may be caused by the increase of transcriptional activity rather than RNA stabilization. To investigate the factors involved in CHX-induced proENK and TH mRNA expression, the effect of CHX on activator protein-1 (AP-1), cAMP response element (CRE) binding protein (CREB), and glucocorticoid response element (GRE) was tested. In AP-1, the basal expression of Fra-2 and c-Jun proteins and AP-1 DNA binding activity in the adrenal medulla was higher than other tissues tested, but CHX reduced these protein levels and AP-1 DNA binding activity. In CREB, CHX time dependently increased the level of phospho-CREB without altering total CRE level and CRE DNA binding activity. Furthermore, phospho-CREB actively participated in CRE DNA binding activity. In GRE, although CHX increased plasma and adrenal corticosterone level, RU486 (10 mg/kg) reduced CHX-induced proENK, but not TH, mRNA level in a partial manner. These results suggest that the basal expression of proENK and TH mRNA transcription in the adrenal gland seems to be tonically inhibited by de novo protein synthesis. In addition, CHX-dependent increase of proENK and TH mRNA expression in the adrenal medulla is well correlated with phospho-CREB level, but not AP-1. Finally, glucocorticoid seems to be involved at least partially in CHX-dependent proENK, but not TH, mRNA expression in the adrenal medulla.

Activating Transcription Factor 2↗

PubMed2006

The strength of the HIV-1 3' splice sites affects Rev function.

BACKGROUND: The HIV-1 Rev protein is a key component in the early to late switch in HIV-1 splicing from early intronless (e.g. tat, rev) to late intron-containing Rev-dependent (e.g. gag, vif, env) transcripts. Previous results suggested that cis-acting sequences and inefficient 5' and 3' splice sites are a prerequisite for Rev function. However, we and other groups have shown that two of the HIV-1 5' splice sites, D1 and D4, are efficiently used in vitro and in vivo. Here, we focus on the efficiency of the HIV-1 3' splice sites taking into consideration to what extent their intrinsic efficiencies are modulated by their downstream cis-acting exonic sequences. Furthermore, we delineate their role in RNA stabilization and Rev function. RESULTS: In the presence of an efficient upstream 5' splice site the integrity of the 3' splice site is not essential for Rev function whereas an efficient 3' splice site impairs Rev function. The detrimental effect of a strong 3' splice site on the amount of Rev-dependent intron-containing HIV-1 glycoprotein coding (env) mRNA is not compensatable by weakening the strength of the upstream 5' splice site. Swapping the HIV-1 3' splice sites in an RRE-containing minigene, we found a 3' splice site usage which was variably dependent on the presence of the usual downstream exonic sequence. The most evident activation of 3' splice site usage by its usual downstream exonic sequence was observed for 3' splice site A1 which was turned from an intrinsic very weak 3' splice site into the most active 3' splice site, even abolishing Rev activity. Performing pull-down experiments with nuclear extracts of HeLa cells we identified a novel ASF/SF2-dependent exonic splicing enhancer (ESE) within HIV-1 exon 2 consisting of a heptameric sequence motif occurring twice (M1 and M2) within this short non-coding leader exon. Single point mutation of M1 within an infectious molecular clone is detrimental for HIV-1 exon 2 recognition without affecting Rev-dependent vif expression. CONCLUSION: Under the conditions of our assay, the rate limiting step of retroviral splicing, competing with Rev function, seems to be exclusively determined by the functional strength of the 3' splice site. The bipartite ASF/SF2-dependent ESE within HIV-1 exon 2 supports cross-talk between splice site pairs across exon 2 (exon definition) which is incompatible with processing of the intron-containing vif mRNA. We propose that Rev mediates a switch from exon to intron definition necessary for the expression of all intron-containing mRNAs.

3' Untranslated Regions↗

PubMed2006

The chemical stability of abasic RNA compared to abasic DNA.

We describe the synthesis of an abasic RNA phosphoramidite carrying a photocleavable 1-(2-nitrophenyl)ethyl (NPE) group at the anomeric center and a triisopropylsilyloxymethyl (TOM) group as 2'-O-protecting group together with the analogous DNA and the 2'-OMe RNA abasic building blocks. These units were incorporated into RNA-, 2'-OMe-RNA- and DNA for the purpose of studying their chemical stabilities towards backbone cleavage in a comparative way. Stability measurements were performed under basic conditions (0.1 M NaOH) and in the presence of aniline (pH 4.6) at 37 degrees C. The kinetics and mechanisms of strand cleavage were followed by High pressure liquid chromotography and ESI-MS. Under basic conditions, strand cleavage at abasic RNA sites can occur via beta,delta-elimination and 2',3'-cyclophosphate formation. We found that beta,delta-elimination was 154-fold slower compared to the same mechanism in abasic DNA. Overall strand cleavage of abasic RNA (including cyclophosphate formation) was still 16.8 times slower compared to abasic DNA. In the presence of aniline at pH 4.6, where only beta,delta-elimination contributes to strand cleavage, a 15-fold reduced cleavage rate at the RNA abasic site was observed. Thus abasic RNA is significantly more stable than abasic DNA. The higher stability of abasic RNA is discussed in the context of its potential biological role.

Aniline Compounds↗

PubMed2000

Transforming growth factor-beta1 expression in cultured corneal fibroblasts in response to injury.

The mechanisms underlying TGF-beta regulation in response to injury are not fully understood. We have developed an in vitro wound model to evaluate the expression and localization of transforming growth factor-beta1 in rabbit corneal fibroblasts in response to injury. Experiments were conducted in the presence or absence of serum so that the effect of the injury could be distinguished from exogenous wound mediators. Cultures were wounded and evaluations conducted over a number of time points. Expression of TGF-beta1 RNA was determined using Northern blot analysis and in situ hybridization, while the TGF-beta receptors were identified by affinity cross-linking. Injury increased the expression of TGF-beta1 mRNA in cells at the wound edge after 30 min; this response was amplified by the addition of serum. TGF-beta1 mRNA expression was observed in a number of cells distal from the wound. After wound closure, TGF-beta1 mRNA was negligible and resembled unwounded cultures. The half-life of TGF-beta1 mRNA was two times greater in the wounded cultures, indicating that the injury itself maintained the expression, while cell migration was present. Analogous to these findings, we found that binding of TGF-beta to its receptors was maximal at the wound edge, decreasing with time and distance from the wound. These results indicate that injury increases the level of expression of TGF-beta1 mRNA and maintains a higher level of receptor binding during events in wound repair and that these might facilitate the migratory and synthetic response of stromal fibroblasts.

Animals↗

PubMed2007

Knock-in mice reveal nonsense-mediated mRNA decay in the brain.

Nonsense-mediated mRNA decay (NMD) is a process of mRNA surveillance that degrades transcripts harboring a premature termination codon (PTC). Mammalian NMD was mostly studied in cultured cells so far and there was no direct evidence yet that NMD could operate in the brain. We introduced, by homologous recombination in mouse, a PTC in the mu opioid receptor gene (mor). mor transcript was severely downregulated in the brain of these knock-in mice. A systemic cycloheximide treatment significantly increased the level of the mutant mRNA, suggesting NMD involvement. To further corroborate this hypothesis, we generated a second knock-in mouse line where the PTC was placed at 10 instead of 96 nucleotides from the downstream splice junction. As predicted by the "termination codon position rule" established in vitro, mor transcript brain expression was rescued to wild-type level. These knock-in mouse lines will be valuable models to better understand and manipulate NMD in vivo.

Animals↗

PubMed2007

DNA cleavage and Trp53 differentially affect SINE transcription.

Among the cellular responses observed following treatment with DNA-damaging agents is the activation of Short Interspersed Elements (SINEs; retrotransposable genetic elements that comprise over 10% of the human genome). By placing a human SINE (the Alu element) into murine cells, we have previously shown that DNA-damaging agents such as etoposide can induce both upregulation of SINE transcript levels and SINE retrotransposition. A similarly cytotoxic (but not genotoxic) exposure to vincristine was not associated with SINE activation. Here we demonstrate that multiple other genotoxic exposures are associated with upregulation of SINE transcript levels. By comparing the effects of similarly cytotoxic doses of the topoisomerase II inhibitors etoposide and merbarone, we confirm that DNA strand breakage is specifically associated with SINE induction. By evaluating transcription rate and RNA stability, we demonstrate that SINE induction by genotoxic exposure is associated with transcriptional induction and not with transcript stabilization. Finally we demonstrate that SINE induction by genotoxic stress is mediated by a Trp53-independent pathway, and in fact that Trp53 plays an inhibitory role in attenuating the transcriptional induction of SINE elements following exposure to a genotoxic agent. Together these data support a model in which initial DNA damage can trigger genomic instability due to SINE activation, a response which may be amplified in cancer cells lacking functional TP53.

Antineoplastic Agents↗

PubMed2001

Developmental regulation of an instability element from the Drosophila fushi tarazu mRNA.

The Drosophila fushi tarazu (ftz) mRNA is one of the shortest-lived metazoan mRNAs, and its instability is crucial for proper development of the embryo. Previously, we identified two cis-acting elements that are required for ftz mRNA degradation, one within the 5' one-third and another in the 3'UTR of the message. Here we focus on the 3'UTR element termed FIE3 (ftz instability element in the 3'UTR). To investigate the developmental regulation of the FIE3-dependent degrading activity we measured the abundance of an FIE3-containing mRNA in ovaries, unfertilized eggs, and different larval and adult tissues. We found that FIE3-degrading activity is present at all developmental stages and tissues examined, except in the ovary. Activation of the FIE3-dependent mRNA decay is independent of fertilization because it could be triggered by egg activation. Finally, we provide evidence that mutation of conserved elements within FIE3 had no effect on mRNA instability.

3' Untranslated Regions↗

PubMed2005

Negative feedback loop formed by Lunatic fringe and Hes7 controls their oscillatory expression during somitogenesis.

Recent studies show that the cyclic expression of Lfng in the presomitic mesoderm (PSM) is controlled at the transcription level by Notch signal through the CBF1 binding site for activation and periodic repression on the Lfng promoter. Here we provide genetic evidence that the oscillatory expression is controlled by a negative feedback mechanism. We also show that Hes7, another cyclically expressed protein, can bind to the N-boxes on both Lfng and its own promoters and repress their activity. In addition, we demonstrate that the 3' untranslated region (3'-UTR) is important for rapid degradation of Lfng mRNA.

3' Untranslated Regions↗

PubMed2004

Analysis of the allele-specific expression of the mismatch repair gene MLH1 using a simple DHPLC-Based Method.

Quantitative measures of allele-specific gene expression allow the indirect detection of mutations or sequence variants in regulatory elements or in other non-coding regions that may result in significant physiological or pathological changes of gene expression and may contribute to Mendelian or multifactorial disorders. We have devised a simple method, based on RT-PCR and single nucleotide primer extension (SNuPE) with unlabelled dideoxynucleotides, followed by DHPLC (denaturing high performance liquid chromatography). We established optimal conditions for separation of the extended products corresponding to the alleles of the c.655A>G (p.Ile219Val) SNP, which is the most frequent exonic polymorphism of MLH1. We then genotyped 99 unrelated control subjects and measured the allele-specific MLH1 expression in the 40 heterozygous controls found in this group. This method allowed us to define a narrow range of normal biallelic expression of MLH1, each allele contributing between 44.7% and 55.3% of the total expression. We then measured the allele-specific expression in hereditary nonpolyposis colorectal cancer (HNPCC) patients with MLH1 mRNAs bearing different stop-codon or frame-shift mutations, or in-frame deletions, in order to detect the effects of nonsense-mediated mRNA decay (NMD). Defects that induce mRNA instability were identified unambiguously and the data were consistent with current models of NMD. This study provides a sensitive tool to identify indirectly MLH1 defects that may escape detection in genomic DNA screenings but result in a quantitative change at the mRNA level.

Adaptor Proteins, Signal Transducing↗

PubMed2007

A common variant located in the 3'UTR of the RET gene is associated with protection from Hirschsprung disease.

Complex diseases are common genetic disorders showing familial aggregation but no typical Mendelian inheritance. Hirschsprung disease (HSCR), a developmental disorder characterized by the absence of enteric neurons in distal segments of the gut, shows a complex pattern of inheritance, with the RET protooncogene acting as a major gene and additional susceptibility loci playing minor roles. In the last years, we have identified a "protective" RET haplotype, which is underrepresented in HSCR patients with respect to controls. Here, we demonstrate that the protective effect of this haplotype is due to a variant located in the 3' untranslated region (UTR) of the RET gene, which slows down the physiological mRNA decay of the gene transcripts. Such a functional effect of this common RET variant explains the under-representation of the whole haplotype and its role as a modifying factor in HSCR pathogenesis.

3' Untranslated Regions↗

PubMed2006

Novel sequence variants in dysferlin-deficient muscular dystrophy leading to mRNA decay and possible C2-domain misfolding.

Mutations in the gene encoding dysferlin (DYSF) cause the allelic autosomal recessive disorders limb girdle muscular dystrophy 2B and Miyoshi myopathy. It encompasses 55 exons spanning 150 kb of genomic DNA. Dysferlin is involved in membrane repair in skeletal muscle. We identified three families with novel sequence variants in DYSF. All affected family members showed limb girdle weakness and had reduced or absent dysferlin protein on immunohistochemistry. All exons of DYSF were screened by genomic sequencing. Five novel variants in DYSF were found: two missense mutations (c.895G>A and c.4022T>C), one 5' donor splice-site variant (c.855+1delG), one nonsense mutation (c.1448C>A), and a variant in the 3'UTR of DYSF (c.*107T>A). All alterations were confirmed by restriction enzyme analysis and not found in 400 control alleles. Nonsense mediated RNA decay or changes in the three-dimensional protein structure resulting in intracellular dysferlin aggregates and finally the lack of dysferlin protein were identified as consequences of the novel DYSF variants.

Adult↗

PubMed2003

Transforming growth factor beta-1 and amphiregulin act in synergy to increase the production of urokinase-type plasminogen activator in transformed breast epithelial cells.

Amphireguline (AR) is an epidermal growth factor (EGF)-related peptide that seems to play an important role in breast cancer progression. We have demonstrated recently that suppression of AR expression in transformed breast epithelial cells considerably reduced both size and neovascularization of tumors developed in nude mice. We show that the reduction of AR expression allowed to an important decrease of the levels of urokinase-type plasminogen activator (uPA) and transforming growth factor-beta1 (TGFbeta1). According to these data, exogenous AR (10(-10) M-10(-8) M) stimulated the production of uPA and TGFbeta1 in AR antisense-transfected A2-15 and A2-P17F25 cells. The addition of 2 x 10(-10) M TGFbeta1 into culture medium increased the level of uPA produced by AR-expressing parental cells but not by A2-15 and A2-P17F25 cell clones. Whereas AR alone stimulated uPA production to 200% of control, combined AR and TGFbeta1 treatment increased protease level in A2-15 and A2-P17F25 cells to 500-600% of control, demonstrating a synergism between TGFbeta1 and AR. This was accompanied by an important augmentation of the number of tumoral cells that invaded matrigel in vitro. The synergistic induction of uPA protein resulted of an early and transient augmentation of steady state mRNA level and was blocked in the presence of the MAP kinase kinase inhibitor PD098059, strongly suggesting that synergistic effect of AR and TGFbeta1 on uPA expression required MAPK pathway. This data demonstrates concerted action between AR and TGFbeta1 that may have profound effect on protease production and consequently on breast cancer progression.

Amphiregulin↗

PubMed2006

Estrogen and progesterone receptor gene polymorphisms and sporadic breast cancer risk: a Spanish case-control study.

Estrogens, and to a lesser extent progesterones, influence the proliferation, differentiation and physiology of breast tissue as well as the development and progression of breast cancer. Genetic variants in the steroid hormone receptor genes ESR1 and PGR (belonging to the nuclear receptor superfamily) could therefore modify sporadic breast cancer susceptibility. Two studies have shown a protective effect associated with variants in ESR1 in 2 distinct populations. We studied 4 single nucleotide polymorphisms (SNPs) in ESR1 and 4 in PGR in 550 consecutive and unrelated sporadic Spanish breast cancer patients and 564 healthy Spanish controls. We observed a dominant protective effect for the S10S variant in ESR1, with an estimated odds ratio (OR) of 0.75 (95% CI = 0.58-0.97; p = 0.03) although functional studies did not show changes in the RNA stability. A small subset of individuals carried a haplotype combination that corroborates this protection. No other SNP considered in either gene was found to be associated with sporadic breast cancer. Our results obtained in a European population confirm the protective role of the S10S variant in ESR1, previously reported in an Asian and a European-American population.

Adult↗