FOS-like Antigen Research Articles

Identification of Modulated Genes by Three Classes of Chemopreventive Agents at Preneoplastic Stages in a p53-Null Mouse Mammary Tumor Model

Genetically engineered mouse cancer models are among the most useful tools for testing the in vivo effectiveness of the various chemopreventive approaches. The p53-null mouse model of mammary carcinogenesis was previously characterized by us at the cellular, molecular, and pathologic levels. In a companion article, Medina et al. analyzed the efficacy of bexarotene, gefitinib, and celecoxib as chemopreventive agents in the same model. Here we report the global gene expression effects on mammary epithelium of such compounds, analyzing the data in light of their effectiveness as chemopreventive agents. SAGE was used to profile the transcriptome of p53-null mammary epithelium obtained from mice treated with each compound versus controls. This information was also compared with SAGE data from p53-null mouse mammary tumors. Gene expression changes induced by the chemopreventive treatments revealed a common core of 87 affected genes across treatments (P < 0.05). The effective compounds, bexarotene and gefitinib, may exert their chemopreventive activity, at least in part, by affecting a set of 34 genes related to specific cellular pathways. The gene expression signature revealed various genes previously described to be associated with breast cancer, such as the activator protein-1 complex member Fos-like antigen 2 (Fosl2), early growth response 1 (Egr1), gelsolin (Gsn), and tumor protein translationally controlled 1 (Tpt1), among others. The concerted modulation of many of these transcripts before malignant transformation seems to be conducive to predominantly decrease cell proliferation. This study has revealed candidate key pathways that can be experimentally tested in the same model system and may constitute novel targets for future translational research.

Evaluation of the Skin Irritation Using a DNA Microarray on a Reconstructed Human Epidermal Model

To avoid the need to use animals to test the skin irritancy potential of chemicals and cosmetics, it is important to establish an in vitro method based on the reconstructed human epidermal model. To evaluate skin irritancy efficiently and sensitively, we determined the gene expression induced by a topically-applied mild irritant sodium dodecyl sulfate (SDS) in a reconstructed human epidermal model LabCyte EPI-MODEL (LabCyte) using a DNA microarray carrying genes that were related to inflammation, immunity, stress and housekeeping. The expression and secretion of IL-1alpha in reconstructed human epidermal culture is known to be induced by irritation. We detected the induction of IL-1alpha expression and its secretion into the cell culture medium by treatment with 0.075% SDS for 18 h in LabCyte culture using DNA microarray, quantitative reverse-transcription polymerase chain reaction (RT-PCR) and ELISA. DNA microarray analysis indicated that the expression of 10 of the 205 genes carried on the DNA microarray was significantly induced in a LabCyte culture by 0.05% or 0.075% SDS irritation for 18 h. RT-PCR analysis confirmed that SDS treatment significantly induced the expressions of interleukin-1 receptor antagonist (IL-1RN), FOS-like antigen 1 (FOSL1), heat shock 70 kDa protein 1A (HSPA1) and myeloid differentiation primary response gene (88) (MYD88), as well as the known marker genes for irritation IL-1beta and IL-8 in a LabCyte culture. Our results showed that a DNA microarray is a useful tool for efficiently evaluating mild skin irritation using a reconstructed human epidermal model.

Microarray analyses in bladder cancer cells: Inhibition of hTERT expression down‐regulates EGFR

The human telomerase reverse transcriptase (hTERT) contributes to the immortal phenotype of the majority of cancers. Targeting hTERT by transfection with antisense oligonucleotides (AS-ODNs) induced immediate growth inhibition in human bladder cancer (BCa) cells. The molecular basis of the antiproliferative capacity of hTERT AS-ODNs was investigated by oligonucleotide microarray analyses and was compared to effects caused by siRNA-mediated knock-down of hTERT in EJ28 BCa cells. Two different AS-ODNs -- both down-regulated the expression of hTERT -- changed the expression of different genes mainly involved in stress response (including EGR1, ATF3 and GDF15), but without an association to telomerase function. This indicates that the immediate growth inhibition was caused, at least in part, by off-target effects. In comparison to that the blockade of the expression of hTERT using 2 different siRNAs was accompanied by the down-regulation of the oncogenes FOS-like antigen 1 (FOSL1) and epidermal growth factor receptor (EGFR), known to be overexpressed in BCa. We show here for the first time that repression of the hTERT transcript number decreased the expression of EGFR both at the mRNA and protein levels, suggesting a potential new function of hTERT in the regulation of EGFR-stimulated proliferation. Furthermore, the suppression of hTERT by siRNAs caused an enhancement of the antiproliferative capacity of the chemotherapeutics mitomycin C and cisplatin. The results presented herein may support the hypothesis that hTERT promotes the growth of tumor cells by mechanisms independent from telomere lengthening. The detailed clarification of these processes will shed light on the question, whether telomerase inhibitors might constitute suitable anticancer tools.

RPL38, FOSL1, and UPP1 Are Predominantly Expressed in the Pancreatic Ductal Epithelium

Establishing more effective treatment of pancreatic cancer requires an understanding of the molecular events leading to the onset and progression of this disease. The biology of tumorigenesis may be better understood if cell type-specific genes in the pancreas are more recognized. This recognition may be as important as discovering a disease-responsible gene. Identification of a ductal epithelium-specific gene can contribute not only to our knowledge of pancreatic tumorigenesis, tumor marker discovery, and effective drug targeting but also is crucial for making a reliable animal model. We used the x-Profiler engine online to compare the SAGE (Serial Analysis of Gene Expression) libraries derived from 2 short-term cultures of normal human ductal epithelial cells from the pancreas against 34 other SAGE libraries generated from other normal human tissues to identify the best candidate gene specific for the ductal epithelium of the pancreas. We identified 3 genes, ribosomal protein L38 (RPL38), uridine phosphorylase (UPP1), and FOS-like antigen-1 (FOSL1), predominantly expressed in the pancreatic ductal epithelium. The expression patterns of these 3 genes were confirmed by virtual Northern analysis, semi-quantitative RT-PCR, and in situ hybridization. Although the expressions of these 3 genes are not completely restricted to the ductal epithelium of the pancreas, we showed that they have more specific expression patterns than CK19 and MUC1. We also demonstrated that all 3 genes are highly expressed in a panel of pancreatic cancer cell lines and can potentially be useful in tumor targeting or as tumor markers.

Fra-1 targets the AP-1 site/2G single nucleotide polymorphism (ETS site) in the MMP-1 promoter.

The matrix metalloproteinase (MMP) family degrades the extracellular matrix. One member of this family, MMP-1, initiates the breakdown of interstitial collagens. The expression of MMP-1 is controlled by the mitogen activated protein kinase (MAPK) pathway(s) via the activity of activator protein-1 (AP-1) and polyoma enhancing activity-3/E26 virus (PEA3/ETS) transcription factors through consensus binding sites present in the promoter. Another ETS site in the MMP-1 promoter is created at -1607 bp by a single nucleotide polymorphism (SNP), which contains two guanines (5'-GGAT-3'; '2G SNP'), rather one guanine (5'-GAT-3'; '1G SNP'), adjacent to an AP-1 binding site at -1602 bp. The 2G SNP displays greater transcriptional activity than the 1G SNP, and AP-1 and Ets families of transcription factors cooperate to increase transcription. The 2G SNP has been linked to the incidence and the progression of several cancers and is also associated with non-neoplastic diseases; although the underlying mechanism(s) has yet to be elucidated. In this study we demonstrate that the expression of Fos-like region antigen (Fra-1), an AP-1 transcription factor component that also correlates strongly with neoplastic disease, is necessary for MMP-1 transcription in A2058 melanoma cells. The inhibition of Fra-1 expression preferentially downregulates transcription from the MMP-1 promoter DNA containing the 2G SNP, compared to DNA containing the 1G SNP. This study provides evidence that, in cooperation with the 2G DNA polymorphism, the AP-1 family member, Fra-1, contributes to the high constitutive expression of MMP-1 in melanoma cells.

Microarray analysis uncovers retinoid targets in human bronchial epithelial cells.

Retinoids, the natural and synthetic derivatives of vitamin A, have a role in cancer treatment and prevention. There is a need to reveal mechanisms that account for retinoid response or resistance. This study identified candidate all-trans-retinoic acid (RA) target genes linked to growth suppression in BEAS-2B human bronchial epithelial cells. Microarray analyses were performed using Affymetrix arrays. A total of 11 RA-induced species were validated by reverse transcription polymerase chain reaction (RT-PCR), Western or Northern analyses. Three of these species were novel candidate RA-target genes in human bronchial epithelial cells. These included: placental bone morphogenetic protein (PLAB), polyamine oxidase isoform 1 (PAOh1) and E74-like factor 3 (ELF3). Expression patterns were studied in RA-resistant BEAS-2B-R1 cells. In BEAS-2B-R1 cells, RA dysregulated the expression of the putative lymphocyte G0/G1 switch gene (G0S2), heme oxygenase 1 (HMOX1), tumor necrosis factor-alpha-induced protein 2 (TNFAIP2), inhibitor of DNA binding 1(Id1), fos-like antigen 1 (FOSL1), transglutaminase 2 (TGM2), asparagine synthetase (ASNS), PLAB, PAOh1 and ELF3, while prominent induction of insulin-like growth-factor-binding protein 6 (IGFBP6) still occurred. In summary, this study identified 11 candidate RA-target genes in human bronchial epithelial cells including three novel species. Expression studies in BEAS-2B-R1 cells indicated that several were directly implicated in RA signaling, since their aberrant expression was linked to RA resistance of human bronchial epithelial cells.