Gene Summary

Gene:TFAP2B; transcription factor AP-2 beta
Aliases: PDA2, AP-2B, AP2-B
Summary:This gene encodes a member of the AP-2 family of transcription factors. AP-2 proteins form homo- or hetero-dimers with other AP-2 family members and bind specific DNA sequences. They are thought to stimulate cell proliferation and suppress terminal differentiation of specific cell types during embryonic development. Specific AP-2 family members differ in their expression patterns and binding affinity for different promoters. This protein functions as both a transcriptional activator and repressor. Mutations in this gene result in autosomal dominant Char syndrome, suggesting that this gene functions in the differentiation of neural crest cell derivatives. [provided by RefSeq, Jul 2008]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:transcription factor AP-2-beta
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 01 September 2019 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (7)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: TFAP2B (cancer-related)

Wu H, Zhang J
Decreased expression of TFAP2B in endometrial cancer predicts poor prognosis: A study based on TCGA data.
Gynecol Oncol. 2018; 149(3):592-597 [PubMed] Related Publications
BACKGROUND: Transcription factor activator protein-2β (TFAP-2β) was previously reported to constituted promoter activity in endometrial carcinoma (EC). We evaluated the role of TFAP2B in ECs using publicly available data from The Cancer Genome Atlas (TCGA).
METHODS: The relationship between clinical pathologic features and TFAP2B were analyzed with the Wilcoxon signed-rank test and logistic regression. Clinicopathologic characteristics associated with overall survival in TCGA patients using Cox regression and the Kaplan-Meier method. Gene Set Enrichment Analysis (GSEA) was performed using TCGA data set.
RESULTS: Reduced TFAP2B expression in EC was significantly associated with high grade (OR=2.2 for well, moderate vs. poor), stage (OR=2.5 for I vs. IV), histology (OR=1.8 for serous vs. endometrioid), distant metastasis (OR=2.4 for positive vs. negative) (all p-values<0.05). Kaplan-Meier survival analysis showed that EC with TFAP2B-low had a worse prognosis than that with TFAP2B-high (p=0.013). The univariate analysis revealed that TFAP2B-low correlated significantly with a poor overall survival (OS) (HR: 2.35; 95% confidence interval [CI]: 1.17-4.73; p=0.016). The multivariate analysis revealed that TFAP2B remained independently associated with overall survival, with a HR of 4.42 (CI: 1.25-12.64; p=0.021). GSEA show that p53/hypoxia pathway, androgen response, notch signaling, fatty acid metabolism, glycolysis and estrogen response late are differentially enriched in TFAP2B high expression phenotype.
CONCLUSIONS: TFAP2B expression may be a potential prognostic molecular marker of poor survival in endometrial cancer, Moreover, the p53/hypoxia, androgen response and notch signaling pathway may be the key pathway regulated by TFAP2B in EC.

Raap M, Gronewold M, Christgen H, et al.
Lobular carcinoma in situ and invasive lobular breast cancer are characterized by enhanced expression of transcription factor AP-2β.
Lab Invest. 2018; 98(1):117-129 [PubMed] Related Publications
Transcription factor AP-2β (TFAP2B) regulates embryonic organ development and is overexpressed in alveolar rhabdomyosarcoma, a rare childhood malignancy. Gene expression profiling has implicated AP-2β in breast cancer (BC). This study characterizes AP-2β expression in the mammary gland and in BC. AP-2β protein expression was assessed in the normal mammary gland epithelium, in various reactive, metaplastic and pre-invasive neoplastic lesions and in two clinical BC cohorts comprising >2000 patients. BCs from various genetically engineered mouse (GEM) models were also evaluated. Human BC cell lines served as functional models to study siRNA-mediated inhibition of AP-2β. The normal mammary gland epithelium showed scattered AP-2β-positive cells in the luminal cell layer. Various reactive and pre-invasive neoplastic lesions, including apocrine metaplasia, usual ductal hyperplasia and lobular carcinoma in situ (LCIS) showed enhanced AP-2β expression. Cases of ductal carcinoma in situ (DCIS) were more often AP-2β-negative (P<0.001). In invasive BC cohorts, AP-2β-positivity was associated with the lobular BC subtype (P<0.001), loss of E-cadherin (P<0.001), a positive estrogen receptor (ER) status (P<0.001), low Ki67 (P<0.001), low/intermediate Oncotype DX recurrence scores (P<0.001), and prolonged event-free survival (P=0.003). BCs from GEM models were all AP-2β-negative. In human BC cell lines, AP-2β expression was independent from ER-signaling. SiRNA-mediated inhibition of AP-2β diminished proliferation of lobular BC cell lines in vitro. In summary, AP-2β is a new mammary epithelial differentiation marker. Its expression is preferentially retained and enhanced in LCIS and invasive lobular BC and has prognostic implications. Our findings indicate that AP-2β controls tumor cell proliferation in this slow-growing BC subtype.

Vastrad B, Vastrad C, Godavarthi A, Chandrashekar R
Molecular mechanisms underlying gliomas and glioblastoma pathogenesis revealed by bioinformatics analysis of microarray data.
Med Oncol. 2017; 34(11):182 [PubMed] Related Publications
The aim of this study was to identify key genes associated with gliomas and glioblastoma and to explore the related signaling pathways. Gene expression profiles of three glioma stem cell line samples, three normal astrocyte samples, three astrocyte overexpressing 4 iPSC-inducing and oncogenic factors (myc(T58A), OCT-4, p53DD, and H-Ras(G12V)) samples, three astrocyte overexpressing 7 iPSC-inducing and oncogenic factors (OCT4, H-Ras(G12V), myc(T58A), p53DD, cyclin D1, CDK4(RC24) and hTERT) samples and three glioblastoma cell line samples were downloaded from the ArrayExpress database (accession: E-MTAB-4771). The differentially expressed genes (DEGs) in gliomas and glioblastoma were identified using FDR and t tests, and protein-protein interaction (PPI) networks for these DEGs were constructed using the protein interaction network analysis. The GeneTrail2 1.5 tool was used to identify potentially enriched biological processes among the DEGs using gene ontology (GO) terms and to identify the related pathways using the Kyoto Encyclopedia of Genes and Genomes, Reactome and WikiPathways pathway database. In addition, crucial modules of the constructed PPI networks were identified using the PEWCC1 plug-in, and their topological properties were analyzed using NetworkAnalyzer, both available from Cytoscape. We also constructed microRNA-target gene regulatory network and transcription factor-target gene regulatory network for these DEGs were constructed using the miRNet and binding and expression target analysis. We identified 200 genes that could potentially be involved in the gliomas and glioblastoma. Among them, bioinformatics analysis identified 137 up-regulated and 63 down-regulated DEGs in gliomas and glioblastoma. The significant enriched pathway (PI3K-Akt) for up-regulated genes such as COL4A1, COL4A2, EGFR, FGFR1, LAPR6, MYC, PDGFA, SPP1 were selected as well as significant GO term (ear development) for up-regulated genes such as CELSR1, CHRNA9, DDR1, FGFR1, GLI2, LGR5, SOX2, TSHR were selected, while the significant enriched pathway (amebiasis) for down-regulated gene such as COL3A1, COL5A2, LAMA2 were selected as well as significant GO term (RNA polymerase II core promoter proximal region sequence-specific binding (5) such as MEIS2, MEOX2, NR2E1, PITX2, TFAP2B, ZFPM2 were selected. Importantly, MYC and SOX2 were hub proteins in the up-regulated PPI network, while MET and CDKN2A were hub proteins in the down-regulated PPI network. After network module analysis, MYC, FGFR1 and HOXA10 were selected as the up-regulated coexpressed genes in the gliomas and glioblastoma, while SH3GL3 and SNRPN were selected as the down-regulated coexpressed genes in the gliomas and glioblastoma. MicroRNA hsa-mir-22-3p had a regulatory effect on the most up DEGs, including VSNL1, while hsa-mir-103a-3p had a regulatory effect on the most down DEGs, including DAPK1. Transcription factor EZH2 had a regulatory effect on the both up and down DEGs, including CD9, CHI3L1, MEIS2 and NR2E1. The DEGs, such as MYC, FGFR1, CDKN2A, HOXA10 and MET, may be used for targeted diagnosis and treatment of gliomas and glioblastoma.

Ren KW, Li YH, Wu G, et al.
Quercetin nanoparticles display antitumor activity via proliferation inhibition and apoptosis induction in liver cancer cells.
Int J Oncol. 2017; 50(4):1299-1311 [PubMed] Related Publications
Quercetin is a potent cancer therapeutic agent and dietary antioxidant present in fruit and vegetables. Quercetin prevents tumor proliferation by inducing cell cycle arrest and is a well known cancer therapeutic agent and autophagy mediator. Recent studies showed that drug delivery by nanoparticles have enhanced efficacy with reduced side effects. In this regard, gold-quercetin into poly(DL-lactide-co-glycolide) nanoparticles was examined. In this study, we explored the role and possible underlying mechanisms of quercetin nanoparticle in regulation of antitumor activity in liver cancer cells. Treatment with quercetin nanoparticle effectively inhibited the liver cancer cell proliferation, cell migration and colony formation, thus suppressing liver cancer progression. Quercetin nanoparticle also upregulated apoptosis markedly. Further study suggested that quercetin nanoparticle accelerated the cleavage of caspase-9, caspase-3, and induced the up-releasing of cytochrome c (Cyto-c), contributing to apoptosis in liver cancer cells. Quercetin nanoparticles also promoted telomerase reverse transcriptase (hTERT) inhibition through reducing AP-2β expression and decreasing its binding to hTERT promoter. In addition, quercetin nanoparticle had an inhibitory role in cyclooxygenase 2 (COX-2) via suppressing the NF-κB nuclear translocation and its binding to COX-2 promoter. Quercetin nanoparticle also inactivated Akt and ERK1/2 signaling pathway. Taken together, our results suggested that quercetin nanoparticle had an antitumor effect by inactivating caspase/Cyto-c pathway, suppressing AP-2β/hTERT, inhibiting NF-κB/COX-2 and impeding Akt/ERK1/2 signaling pathways. Our results provided new mechanistic basis for further investigation of quercetin nanoparticles to find potential therapeutic strategies and possible targets for liver cancer inhibition.

Kitchen MO, Bryan RT, Emes RD, et al.
Quantitative genome-wide methylation analysis of high-grade non-muscle invasive bladder cancer.
Epigenetics. 2016; 11(3):237-46 [PubMed] Free Access to Full Article Related Publications
High-grade non-muscle invasive bladder cancer (HG-NMIBC) is a clinically unpredictable disease with greater risks of recurrence and progression relative to their low-intermediate-grade counterparts. The molecular events, including those affecting the epigenome, that characterize this disease entity in the context of tumor development, recurrence, and progression, are incompletely understood. We therefore interrogated genome-wide DNA methylation using HumanMethylation450 BeadChip arrays in 21 primary HG-NMIBC tumors relative to normal bladder controls. Using strict inclusion-exclusion criteria we identified 1,057 hypermethylated CpGs within gene promoter-associated CpG islands, representing 256 genes. We validated the array data by bisulphite pyrosequencing and examined 25 array-identified candidate genes in an independent cohort of 30 HG-NMIBC and 18 low-intermediate-grade NMIBC. These analyses revealed significantly higher methylation frequencies in high-grade tumors relative to low-intermediate-grade tumors for the ATP5G2, IRX1 and VAX2 genes (P<0.05), and similarly significant increases in mean levels of methylation in high-grade tumors for the ATP5G2, VAX2, INSRR, PRDM14, VSX1, TFAP2b, PRRX1, and HIST1H4F genes (P<0.05). Although inappropriate promoter methylation was not invariantly associated with reduced transcript expression, a significant association was apparent for the ARHGEF4, PON3, STAT5a, and VAX2 gene transcripts (P<0.05). Herein, we present the first genome-wide DNA methylation analysis in a unique HG-NMIBC cohort, showing extensive and discrete methylation changes relative to normal bladder and low-intermediate-grade tumors. The genes we identified hold significant potential as targets for novel therapeutic intervention either alone, or in combination, with more conventional therapeutic options in the treatment of this clinically unpredictable disease.

Ikram F, Ackermann S, Kahlert Y, et al.
Transcription factor activating protein 2 beta (TFAP2B) mediates noradrenergic neuronal differentiation in neuroblastoma.
Mol Oncol. 2016; 10(2):344-59 [PubMed] Free Access to Full Article Related Publications
Neuroblastoma is an embryonal pediatric tumor that originates from the developing sympathetic nervous system and shows a broad range of clinical behavior, ranging from fatal progression to differentiation into benign ganglioneuroma. In experimental neuroblastoma systems, retinoic acid (RA) effectively induces neuronal differentiation, and RA treatment has been therefore integrated in current therapies. However, the molecular mechanisms underlying differentiation are still poorly understood. We here investigated the role of transcription factor activating protein 2 beta (TFAP2B), a key factor in sympathetic nervous system development, in neuroblastoma pathogenesis and differentiation. Microarray analyses of primary neuroblastomas (n = 649) demonstrated that low TFAP2B expression was significantly associated with unfavorable prognostic markers as well as adverse patient outcome. We also found that low TFAP2B expression was strongly associated with CpG methylation of the TFAP2B locus in primary neuroblastomas (n = 105) and demethylation with 5-aza-2'-deoxycytidine resulted in induction of TFAP2B expression in vitro, suggesting that TFAP2B is silenced by genomic methylation. Tetracycline inducible re-expression of TFAP2B in IMR-32 and SH-EP neuroblastoma cells significantly impaired proliferation and cell cycle progression. In IMR-32 cells, TFAP2B induced neuronal differentiation, which was accompanied by up-regulation of the catecholamine biosynthesizing enzyme genes DBH and TH, and down-regulation of MYCN and REST, a master repressor of neuronal genes. By contrast, knockdown of TFAP2B by lentiviral transduction of shRNAs abrogated RA-induced neuronal differentiation of SH-SY5Y and SK-N-BE(2)c neuroblastoma cells almost completely. Taken together, our results suggest that TFAP2B is playing a vital role in retaining RA responsiveness and mediating noradrenergic neuronal differentiation in neuroblastoma.

Fu L, Shi K, Wang J, et al.
TFAP2B overexpression contributes to tumor growth and a poor prognosis of human lung adenocarcinoma through modulation of ERK and VEGF/PEDF signaling.
Mol Cancer. 2014; 13:89 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: TFAP2B is a member of the AP2 transcription factor family, which orchestrates a variety of cell processes. However, the roles of TFAP2B in regulating carcinogenesis remain largely unknown. Here, we investigated the regulatory effects of TFAP2B on lung adenocarcinomas growth and identified the underlying mechanisms of actions in non-small cell lung cancer (NSCLC) cells.
METHODS: We first examined the expression of TFAP2B in lung cancer cell lines and tumor tissues. We also analyzed the prognostic predicting value of TFAP2B in lung adenocarcinomas. Then we investigated the molecular mechanisms by which TFAP2B knockdown or overexpression regulated lung cancer cell growth, angiogenesis and apoptosis, and further confirmed the role of TFAP2B in tumor growth in a lung cancer xenograft mouse model.
RESULTS: TFAP2B was highly expressed in NSCLC cell lines and tumor tissues. Strong TFAP2B expression showed a positive correlation with the poor prognoses of patients with lung adenocarcinomas (P < 0.001). TFAP2B knockdown by siRNA significantly inhibited cell growth and induced apoptosis in NSCLC cells in vitro and in a lung cancer subcutaneous xenograft model, whereas TFAP2B overexpression promoted cell growth. The observed regulation of cell growth was accompanied by the TFAP2B-mediated modulation of the ERK/p38, caspase/cytochrome-c and VEGF/PEDF-dependent signaling pathways in NSCLC cells.
CONCLUSIONS: These results indicate that TFAP2B plays a critical role in regulating lung adenocarcinomas growth and could serve as a promising therapeutic target for lung cancer treatment.

Otto B, Streichert T, Wegwitz F, et al.
Transcription factors link mouse WAP-T mammary tumors with human breast cancer.
Int J Cancer. 2013; 132(6):1311-22 [PubMed] Related Publications
Mouse models are important tools to decipher the molecular mechanisms of mammary carcinogenesis and to mimic the respective human disease. Despite sharing common phenotypic and genetic features, the proper translation of murine models to human breast cancer remains a challenging task. In a previous study we showed that in the SV40 transgenic WAP-T mice an active Met-pathway and epithelial-mesenchymal characteristics distinguish low- and high-grade mammary carcinoma. To assign these murine tumors to corresponding human tumors we here incorporated the analysis of expression of transcription factor (TF) coding genes and show that thereby a more accurate interspecies translation can be achieved. We describe a novel cross-species translation procedure and demonstrate that expression of unsupervised selected TFs, such as ELF5, HOXA5 and TFCP2L1, can clearly distinguish between the human molecular breast cancer subtypes--or as, for example, expression of TFAP2B between yet unclassified subgroups. By integrating different levels of information like histology, gene set enrichment, expression of differentiation markers and TFs we conclude that tumors in WAP-T mice exhibit similarities to both, human basal-like and non-basal-like subtypes. We furthermore suggest that the low- and high-grade WAP-T tumor phenotypes might arise from distinct cells of tumor origin. Our results underscore the importance of TFs as common cross-species denominators in the regulatory networks underlying mammary carcinogenesis.

van Waas M, Neggers SJ, Uitterlinden AG, et al.
Treatment factors rather than genetic variation determine metabolic syndrome in childhood cancer survivors.
Eur J Cancer. 2013; 49(3):668-75 [PubMed] Related Publications
BACKGROUND: Genetic variation that regulates insulin resistance, blood pressure and adiposity in the normal population might determine differential vulnerability for metabolic syndrome after treatment for childhood cancer.
OBJECTIVE: To evaluate the contribution of candidate single nucleotide polymorphisms (SNPs) relevant for metabolic syndrome in our single centre cohort of adult long-term childhood cancer survivors.
METHODS: In this retrospective study 532 survivors were analysed. Median age at diagnosis was 5.7 years (range 0.0-17.8 years), median follow-up time was 17.9 years (range 5.0-48.8) and median age at follow-up was 25.6 years (range 18.0-50.8). JAZF1 gene rs864745, THADA gene rs7578597, IRS1 gene rs2943641, TFAP2B gene rs987237, MSRA gene rs7826222, ATP2B1 gene rs2681472 and rs2681492 were genotyped. The association of genotypes with total cholesterol levels, blood pressure, body mass index, waist circumference and frequency of diabetes were assessed.
RESULTS: Metabolic syndrome was more frequent in cranially (23.3%, P=0.002) and abdominally (23.4%, P=0.009) irradiated survivors as compared with non-irradiated survivors (10.0%). Association of allelic variants in rs2681472 and rs2681492 with hypertension, rs987237 and rs7826222 with waist circumference and rs864745, rs7578597 and rs2943641 with diabetes were not significant. None of the SNPs was associated with the metabolic syndrome. Adjusting for age, sex, follow-up time, cranial irradiation and abdominal irradiation did not change these results.
CONCLUSIONS: Treatment factors and not genetic variation determine hypertension, waist circumference, diabetes and metabolic syndrome in adult long-term survivors of childhood cancer.

Cizkova M, Cizeron-Clairac G, Vacher S, et al.
Gene expression profiling reveals new aspects of PIK3CA mutation in ERalpha-positive breast cancer: major implication of the Wnt signaling pathway.
PLoS One. 2010; 5(12):e15647 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The PI3K/AKT pathway plays a pivotal role in breast cancer development and maintenance. PIK3CA, encoding the PI3K catalytic subunit, is the oncogene exhibiting a high frequency of gain-of-function mutations leading to PI3K/AKT pathway activation in breast cancer. PIK3CA mutations have been observed in 30% to 40% of ERα-positive breast tumors. However the physiopathological role of PIK3CA mutations in breast tumorigenesis remains largely unclear.
METHODOLOGY/PRINCIPAL FINDINGS: To identify relevant downstream target genes and signaling activated by aberrant PI3K/AKT pathway in breast tumors, we first analyzed gene expression with a pangenomic oligonucleotide microarray in a series of 43 ERα-positive tumors with and without PIK3CA mutations. Genes of interest were then investigated in 249 ERα-positive breast tumors by real-time quantitative RT-PCR. A robust collection of 19 genes was found to be differently expressed in PIK3CA-mutated tumors. PIK3CA mutations were associated with over-expression of several genes involved in the Wnt signaling pathway (WNT5A, TCF7L2, MSX2, TNFRSF11B), regulation of gene transcription (SEC14L2, MSX2, TFAP2B, NRIP3) and metal ion binding (CYP4Z1, CYP4Z2P, SLC40A1, LTF, LIMCH1).
CONCLUSION/SIGNIFICANCE: This new gene set should help to understand the behavior of PIK3CA-mutated cancers and detailed knowledge of Wnt signaling activation could lead to novel therapeutic strategies.

Li X, Glubrecht DD, Godbout R
AP2 transcription factor induces apoptosis in retinoblastoma cells.
Genes Chromosomes Cancer. 2010; 49(9):819-30 [PubMed] Free Access to Full Article Related Publications
The underlying cause of human retinoblastoma is complete inactivation of both copies of the RB1 gene. Other chromosome abnormalities, with the most common being extra copies of chromosome arm 6p, are also observed in retinoblastoma. The RB protein has previously been shown to interact with TFAP2 transcription factors. Here, we show that TFAP2A and TFAP2B, which map to chromosome arm 6p, are expressed in the amacrine and horizontal cells of human retina. TFAP2A RNA can readily be detected in retinoblastoma cell lines and tumors; however, the great majority of retinoblastoma cell lines and tumors are completely devoid of TFAP2A protein and TFAP2B RNA/protein. Transfection of TFAP2A and TFAP2B expression constructs into retinoblastoma cells induces apoptosis and inhibits proliferation. Our results suggest that a consequence of loss of RB1 gene function in retinoblastoma cells is inactivation of TFAP2A and TFAP2B function. We propose that inability to differentiate along the amacrine/horizontal cell lineages may underlie retinoblastoma tumor formation.

Tun HW, Marlow LA, von Roemeling CA, et al.
Pathway signature and cellular differentiation in clear cell renal cell carcinoma.
PLoS One. 2010; 5(5):e10696 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Clear cell renal cell carcinoma (ccRCC) is the most common kidney cancer. The purpose of this study is to define a biological pathway signature and a cellular differentiation program in ccRCC.
METHODOLOGY: We performed gene expression profiling of early-stage ccRCC and patient-matched normal renal tissue using Affymetrix HG-U133a and HG-U133b GeneChips combined with a comprehensive bioinformatic analyses, including pathway analysis. The results were validated by real time PCR and IHC on two independent sample sets. Cellular differentiation experiments were performed on ccRCC cell lines and their matched normal renal epithelial cells, in differentiation media, to determine their mesenchymal differentiation potential.
PRINCIPAL FINDINGS: We identified a unique pathway signature with three major biological alterations-loss of normal renal function, down-regulated metabolism, and immune activation-which revealed an adipogenic gene expression signature linked to the hallmark lipid-laden clear cell morphology of ccRCC. Culturing normal renal and ccRCC cells in differentiation media showed that only ccRCC cells were induced to undergo adipogenic and, surprisingly, osteogenic differentiation. A gene expression signature consistent with epithelial mesenchymal transition (EMT) was identified for ccRCC. We revealed significant down-regulation of four developmental transcription factors (GATA3, TFCP2L1, TFAP2B, DMRT2) that are important for normal renal development.
CONCLUSIONS: ccRCC is characterized by a lack of epithelial differentiation, mesenchymal/adipogenic transdifferentiation, and pluripotent mesenchymal stem cell-like differentiation capacity in vitro. We suggest that down-regulation of developmental transcription factors may mediate the aberrant differentiation in ccRCC. We propose a model in which normal renal epithelial cells undergo dedifferentiation, EMT, and adipogenic transdifferentiation, resulting in ccRCC. Because ccRCC cells grown in adipogenic media regain the characteristic ccRCC phenotype, we have identified a new in vitro ccRCC cell model more resembling ccRCC tumor morphology.

Bourdeaut F, Janoueix-Lerosey I, Lucchesi C, et al.
Cholinergic switch associated with morphological differentiation in neuroblastoma.
J Pathol. 2009; 219(4):463-72 [PubMed] Related Publications
The morphology of malignant cells distinguishes between undifferentiated, poorly differentiated and differentiating neuroblastomas and constitutes a strong prognostic factor. Spontaneous or treatment-induced maturation characterizes a subset of neuroblastomas. It constitutes the basis of retinoic acid treatment to improve survival in aggressive neuroblastomas. However, the molecular events that drive differentiation are poorly understood. In the present study we have investigated the relationships between gene expression profiles and differentiation criteria in stroma-poor neuroblastomas. This study included three undifferentiated (UN), 20 poorly differentiated (PDN) and 11 differentiating (DN) neuroblastomas. These groups could be clearly separated using unsupervised clustering methods, which further enabled a major classification impact of genes involved in neural development, differentiation and function to be identified. UNs are characterized by high ASCL1, high PHOX2B, low GATA2, low TH and low DBH expressions. Most PDNs harbour a clear adrenergic phenotype, even in the presence of missense PHOX2B mutations. Finally, all DN tumours demonstrate cholinergic features. Depending upon their association with adrenergic characteristics, this enables dual 'cholinergic/adrenergic' and 'fully cholinergic' neuroblastomas to be defined. This suggests that the cholinergic switch, a final specification process that occurs physiologically in a minority of sympathetic neurons, is a critical step of differentiation in some neuroblastic tumours. This switch is associated with a down regulation of DBH that is apparently not strictly dependent upon PHOX2B. Conversely, GATA2 and TFAP2B may play critical roles in maintaining adrenergic features in poorly differentiated tumours.

Davicioni E, Anderson MJ, Finckenstein FG, et al.
Molecular classification of rhabdomyosarcoma--genotypic and phenotypic determinants of diagnosis: a report from the Children's Oncology Group.
Am J Pathol. 2009; 174(2):550-64 [PubMed] Free Access to Full Article Related Publications
Rhabdomyosarcoma (RMS) in children occurs as two major histological subtypes, embryonal (ERMS) and alveolar (ARMS). ERMS is associated with an 11p15.5 loss of heterozygosity (LOH) and may be confused with nonmyogenic, non-RMS soft tissue sarcomas. ARMS expresses the product of a genomic translocation that fuses FOXO1 (FKHR) with either PAX3 or PAX7 (P-F); however, at least 25% of cases lack these translocations. Here, we describe a genomic-based classification scheme that is derived from the combined gene expression profiling and LOH analysis of 160 cases of RMS and non-RMS soft tissue sarcomas that is at variance with conventional histopathological schemes. We found that gene expression profiles and patterns of LOH of ARMS cases lacking P-F translocations are indistinguishable from conventional ERMS cases. A subset of tumors that has been histologically classified as RMS lack myogenic gene expression. However, classification based on gene expression is possible using as few as five genes with an estimated error rate of less than 5%. Using immunohistochemistry, we characterized two markers, HMGA2 and TFAP2ss, which facilitate the differential diagnoses of ERMS and P-F RMS, respectively, using clinical material. These objectively derived molecular classes are based solely on genomic analysis at the time of diagnosis and are highly reproducible. Adoption of these molecular criteria may offer a more clinically relevant diagnostic scheme, thus potentially improving patient management and therapeutic RMS outcomes.

Albino D, Scaruffi P, Moretti S, et al.
Identification of low intratumoral gene expression heterogeneity in neuroblastic tumors by genome-wide expression analysis and game theory.
Cancer. 2008; 113(6):1412-22 [PubMed] Related Publications
BACKGROUND: Neuroblastic tumors (NTs) are largely comprised of neuroblastic (Nb) cells with various quantities of Schwannian stromal (SS) cells. NTs show a variable genetic heterogeneity. NT gene expression profiles reported so far have not taken into account the cellular components. The authors reported the genome-wide expression analysis of whole tumors and microdissected Nb and SS cells.
METHODS: The authors analyzed gene expression profiles of 10 stroma-poor NTs (NTs-SP) and 9 stroma-rich NTs (NTs-SR) by microarray technology. Nb and SS cells were isolated by laser microdissection from NTs-SP and NTs-SR and probed with microarrays. Gene expression data were analyzed by the Significance Analysis of Microarrays (SAM) and Game Theory (GT) methods, the latter applied for the first time to microarray data evaluation.
RESULTS: SAM identified 84 genes differentially expressed between NTs-SP and NTs-SR, whereas 50 were found by GT. NTs-SP mainly express genes associated with cell replication, nervous system development, and antiapoptotic pathways, whereas NTs-SR express genes of cell-cell communication and apoptosis. Combining SAM and GT, the authors found 16 common genes driving the separation between NTs-SP and NTs-SR. Five genes overexpressed in NTs-SP encode for nuclear proteins (CENPF, EYA1, PBK, TOP2A, TFAP2B), whereas only 1 of 11 highly expressed genes in NTs-SR encodes for a nuclear receptor (NR4A2).
CONCLUSIONS: The results showed that NT-SP and NT-SR gene signatures differ for a set of genes involved in distinct pathways, and the authors demonstrated a low intratumoral heterogeneity at the mRNA level in both NTs-SP and NTs-SR. The combination of SAM and GT methods may help to better identify gene expression profiling in NTs.

Mitchell DC, Abdelrahim M, Weng J, et al.
Regulation of KiSS-1 metastasis suppressor gene expression in breast cancer cells by direct interaction of transcription factors activator protein-2alpha and specificity protein-1.
J Biol Chem. 2006; 281(1):51-8 [PubMed] Related Publications
KiSS-1 has been shown to function as a tumor metastasis suppressor gene and reduce the number of metastases in different cancers. The expression of KiSS-1 or KiSS1, like other tumor suppressor, is commonly reduced or completely ablated in a variety of cancers via an unknown mechanism. Here we show that the loss of KiSS-1 expression in highly metastatic breast cancer cell lines correlates directly with the expression levels of two transcription factors, activator protein-2alpha (AP-2alpha) and specificity protein 1 (Sp1), which synergistically activate the transcriptional regulation of KiSS-1 in breast cancer cells. Although the KiSS-1 promoter contains multiple AP-2alpha binding elements, AP-2alpha-mediated regulation occurs indirectly through Sp1 sites, as determined by deletion and mutation analysis. Overexpression of AP-2alpha into highly metastatic breast cell lines did not alter KiSS-1 promoter-driven luciferase gene activity. However, co-transfection of AP-2alpha wild-type or the dominant negative form of AP-2 lacking its C-terminal DNA-binding domain, AP-2B, together with Sp1, increased KiSS-1 promoter activity dramatically, suggesting that AP-2alpha regulation of KiSS-1 transcription does not require direct binding to the KiSS-1 promoter. Furthermore, we demonstrated that AP-2alpha directly interacted with Sp1 to form transcription complexes at two tandem Sp1-binding sites of the promoter to activate KiSS-1 transcription. Together, our results indicate that AP-2alpha and Sp1 are strong transcriptional regulators of KiSS-1 and that loss or decreased expression of AP-2alpha in breast cancer may account for the loss of tumor metastasis suppressor KiSS-1 expression and thus increased cancer metastasis.

Turashvili G, Bouchal J, Burkadze G, Kolár Z
Differentiation of tumours of ductal and lobular origin: II. Genomics of invasive ductal and lobular breast carcinomas.
Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2005; 149(1):63-8 [PubMed] Related Publications
Breast cancer is considered to be a multifactorial disorder caused by both genetic and non-genetic factors. Different histological types of breast cancer differ in response to treatment and may have a divergent clinical course. Breast tissue is heterogeneous, with components of epithelial, mesenchymal, endothelial and lymphopoietic derivation. The genetic heterogeneity of invasive breast cancer is reflected by the wide spectrum of histological types and differentiation grades. Nevertheless, the influences of these cell types on the tumour's total pattern of gene expression can be estimated analytically. Microarrays permit total tissue analysis and provide a stable molecular portrait of tumours. Some investigations suggest differences in the gene expression profiling for ductal and lobular carcinomas. It has been reported that inactivating mutations of the E-cadherin gene are very frequent in infiltrating lobular breast carcinomas. Other than altered expression of E-cadherin, little is known about the underlying biology that distinguishes ductal and lobular tumour subtypes. However, about 8 genes have been identified differentially which are expressed in lobular and ductal cancers: E-CD, survivin, cathepsin B, TPI1, SPRY1, SCYA14, TFAP2B, and thrombospondin 4, osteopontin, HLA-G, and CHC1. Expression profiling of breast cancers can be used diagnostically to distinguish individual histologic subclassifications and may guide the selection of target therapeutics. However, future approaches will need to include methods for high throughput clinical validation and the ability to analyze microscopic samples.

Fujimori K, Kadoyama K, Urade Y
Protein kinase C activates human lipocalin-type prostaglandin D synthase gene expression through de-repression of notch-HES signaling and enhancement of AP-2 beta function in brain-derived TE671 cells.
J Biol Chem. 2005; 280(18):18452-61 [PubMed] Related Publications
Here we investigated the regulatory mechanism of lipocalin-type prostaglandin D synthase (L-PGDS) gene expression in human TE671 (medulloblastoma of cerebellum) cells. Reporter analysis of the promoter region from -730 to +75 of the human L-PGDS gene demonstrated that deletion or mutation of the N-box at -337 increased the promoter activity 220-300%. The N-box was bound by Hes-1, a mammalian homologue of Drosophila Hairy and enhancer of split, as examined by electrophoretic mobility shift assay and chromatin immunoprecipitation assay. Functional expression of the Notch intracellular domain significantly increased Hes-1 expression and decreased L-PGDS expression level in TE671 cells. Moreover, knock-down of Hes-1 mRNA by RNA interference significantly enhanced the L-PGDS mRNA level, indicating that the L-PGDS gene expression is repressed by the Notch-Hes signaling. When the AP-2 element at -98 of the promoter region was deleted or mutated, the promoter activity was drastically decreased to approximately 10% of normal. The AP-2 element was bound by AP-2beta dominantly expressed in TE671 cells, according to the results of electrophoretic mobility shift assay and chromatin immunoprecipitation assay. L-PGDS expression was induced by 12-O-tetradecanoylphorbol-13-acetate in TE671 cells, and this induction was inhibited by a protein kinase C inhibitor. Stimulation of TE671 cells with 12-O-tetradecanoylphorbol-13-acetate or transfection with protein kinase Calpha expression vector induced phosphorylation of Hes-1, inhibition of DNA binding of Hes-1 to the N-box, and activation of the AP-2beta function to up-regulate L-PGDS gene expression. These results reveal a novel transcriptional regulatory mechanism responsible for the high level expression of the human L-PGDS gene in TE671 cells.

Oya M, Mikami S, Mizuno R, et al.
Differential expression of activator protein-2 isoforms in renal cell carcinoma.
Urology. 2004; 64(1):162-7 [PubMed] Related Publications
OBJECTIVES: To investigate the expression of activator protein-2 (AP-2) in renal cell carcinoma (RCC) by immunohistochemistry. Three AP-2 isoforms alpha (alpha), beta (beta), and gamma (gamma) are known to exhibit a highly homologous structure; however, their functions are considered to be different. AP-2 has been implicated to play a role in carcinogenesis, as well as in the development of the kidney.
METHODS: The expression of the three AP-2 isoforms, alpha, beta, and gamma, was determined in 58 patients with RCC by immunohistochemistry. Epidermal growth factor receptor and erbB2 expression in 42 patients with RCC was also evaluated to investigate the correlation with AP-2 isoforms.
RESULTS: AP-2 isoforms are differentially expressed in normal renal tubules. Of 58 RCC tissue specimens, 15 (25.9%) demonstrated nuclear and cytoplasmic expression of AP-2alpha. Clear cell RCC had a significantly greater rate of AP-2alpha expression than the nonclear subtypes (14 of 41 clear versus 1 of 17 nonclear subtypes). Of the 58 specimens, 8 (13.8%) showed nuclear staining for AP-2beta; notably, localized small cases had a significantly greater rate of nuclear staining for AP-2beta (5 of 13 in pT1a versus 3 of 45 in pT1b or greater). In addition, only 2 cases (3.5%) demonstrated nuclear staining for AP-2gamma. Epidermal growth factor receptor and erbB2 expression did not correlate with expression of the AP-2 isoforms.
CONCLUSIONS: AP-2 isoforms were differentially expressed in RCC, as well as in the adult normal kidney. AP-2alpha was dominantly expressed in clear cell RCC. AP-2beta expression was observed in the low-stage subtypes of RCC, and this transcription factor may be related to early carcinogenesis.

Korkola JE, DeVries S, Fridlyand J, et al.
Differentiation of lobular versus ductal breast carcinomas by expression microarray analysis.
Cancer Res. 2003; 63(21):7167-75 [PubMed] Related Publications
Invasive lobular and ductal breast tumors have distinct histologies and clinical presentation. Other than altered expression of E-cadherin, little is known about the underlying biology that distinguishes the tumor subtypes. We used cDNA microarrays to identify genes differentially expressed between lobular and ductal tumors. Unsupervised clustering of tumors failed to distinguish between the two subtypes. Prediction analysis for microarrays (PAM) was able to predict tumor type with an accuracy of 93.7%. Genes that were significantly differentially expressed between the two groups were identified by MaxT permutation analysis using t tests (20 cDNA clones and 10 unique genes), significance analysis for microarrays (33 cDNA clones and 15 genes, at an estimated false discovery rate of 2%), and PAM (31 cDNAs and 15 genes). There were 8 genes identified by all three of these related methods (E-cadherin, survivin, cathepsin B, TPI1, SPRY1, SCYA14, TFAP2B, and thrombospondin 4), and an additional 3 that were identified by significance analysis for microarrays and PAM (osteopontin, HLA-G, and CHC1). To validate the differential expression of these genes, 7 of them were tested by real-time quantitative PCR, which verified that they were differentially expressed in lobular versus ductal tumors. In conclusion, specific changes in gene expression distinguish lobular from ductal breast carcinomas. These genes may be important in understanding the basis of phenotypic differences among breast cancers.

Orso F, Cottone E, Hasleton MD, et al.
Activator protein-2gamma (AP-2gamma) expression is specifically induced by oestrogens through binding of the oestrogen receptor to a canonical element within the 5'-untranslated region.
Biochem J. 2004; 377(Pt 2):429-38 [PubMed] Free Access to Full Article Related Publications
The activator protein 2 (AP-2) transcription factors are essential proteins for oestrogenic repression of the ERBB2 proto-oncogene in breast cancer cells. In the present study, we have examined the possible oestrogenic regulation of AP-2 genes themselves in breast-tumour-derived lines. As early as 1 h after oestrogen treatment, AP-2gamma mRNA was markedly increased, whereas AP-2alpha was down-regulated, but with slower kinetics, and AP-2beta was not affected at all. Addition of anti-oestrogens ablated these effects. Modulation of the protein levels corresponded to changes in the transcript levels, thus suggesting that in oestrogen-treated cells, an inversion of the balance between AP-2alpha and AP-2gamma isoforms occurs. The 5'-untranslated region (5'-UTR) of the human AP-2gamma gene contains one consensus and one degenerate oestrogen-responsive element (ERE). Reporter constructs carrying the AP-2gamma promoter and the 5'-UTR were up-regulated by oestrogens in transient transfection assays. Deletion of the most conserved (but not of the degenerate) ERE from reporter constructs abrogated the oestrogenic response, although both ERE-containing segments were footprinted in DNaseI protection assays. In vitro binding assays demonstrated the ability of oestrogen receptor alpha (ERalpha) to bind to this site, and chromatin immunoprecipitation analysis of the endogenous gene showed that ERalpha occupies this region in response to oestrogens. We conclude that AP-2gamma is a primary oestrogen-responsive gene and suggest that AP-2 proteins may mediate some oestrogenic responses.

Nyormoi O, Bar-Eli M
Transcriptional regulation of metastasis-related genes in human melanoma.
Clin Exp Metastasis. 2003; 20(3):251-63 [PubMed] Related Publications
Melanoma begins with benign nevi and progresses to radial growth phase (RGP) and to vertical growth phase [(VGP), metastatic phenotype]. The molecular changes associated with these transitions are not yet well defined. However, transcriptional regulation of some genes that are critical in melanoma progression is beginning to be elucidated. The first part of this review will focus on our recent studies demonstrating that progression of human melanoma is associated with loss of expression of the transcription factor AP-2. In metastatic melanoma cells, this loss resulted in overexpression of MCAM/MUC18 and MMP-2, and lack of expression of c-KIT. In further investigations, we inactivated AP-2 in SB-2 primary cutaneous melanoma cells by using a dominant-negative AP-2, the AP-2B gene. Expression of AP-2B in SB-2 cells augmented their tumorigenicity in nude mice and upregulated MMP-2 expression and activity. We have also recently demonstrated that loss of AP-2 expression in metastatic melanoma cells resulted in overproduction of the thrombin receptor, PAR-1. Other studies have shown that AP-2 regulates additional genes involved in melanoma development and progression, including E-cadherin, p21/WAF-1, HER2, Bcl-2, FAS/APO-1, IGF-R-1, and VEGF. We propose that loss of AP-2 is crucial in the development of malignant melanoma. Additionally, the transition of melanoma cells from RGP to VGP is associated with overexpression of two transcription factors, CREB and ATF-1, both of which may act as survival factors for human melanoma cells. The second part of the review will briefly discuss the role of other transcription factors, including ATF-2, SNAIL, MITF, and NFkappaB in the progression of human melanoma and will summarize recent knowledge on how changes in the expression of these transcription factors contribute to acquisition of the metastatic phenotype in human melanoma.

Cho YS, Kim MK, Cheadle C, et al.
A genomic-scale view of the cAMP response element-enhancer decoy: a tumor target-based genetic tool.
Proc Natl Acad Sci U S A. 2002; 99(24):15626-31 [PubMed] Free Access to Full Article Related Publications
Enhancer DNA decoy oligodeoxynucleotides (ODNs) inhibit transcription by competing for transcription factors. A decoy ODN composed of the cAMP response element (CRE) inhibits CRE-directed gene transcription and tumor growth without affecting normal cell growth. Here, we use DNA microarrays to analyze the global effects of the CRE-decoy ODN in cancer cell lines and in tumors grown in nude mice. The CRE-decoy up-regulates the AP-2beta transcription factor gene in tumors but not in the livers of host animals. The up-regulated expression of AP-2beta is clustered with the up-regulation of other genes involved in development and cell differentiation. Concomitantly, another cluster of genes involved in cell proliferation and transformation is down-regulated. The observed alterations indicate that CRE-directed transcription favors tumor growth. The CRE-decoy ODN, therefore, may serve as a target-based genetic tool to treat cancer and other diseases in which CRE-directed transcription is abnormally used.

Zhu CH, Domann FE
Dominant negative interference of transcription factor AP-2 causes inhibition of ErbB-3 expression and suppresses malignant cell growth.
Breast Cancer Res Treat. 2002; 71(1):47-57 [PubMed] Related Publications
ErbB-3 (HER3) is a member of the epidermal growth factor receptor family. Increasing evidence suggests that elevated expression of ErbB-3 is important for malignancy. In this study, we found that elevated levels of ErbB-3 expression did not occur in the absence of AP-2gamma in a panel of human mammary epithelial and fibroblasts cell lines. In contrast, there was no association between the expression of AP-2alpha or AP-2beta and the level of ErbB-3, or between AP-2alpha and AP-2gamma double positivity and ErbB-3 expression. In co-transfection experiments, exogenous expression of AP-2gamma robustly activated ErbB-3 promoter activity. Moreover, expression of a dominant negative AP-2 protein, AP-2delta (deleted residues 31-117), not only repressed the ErbB-3 promoter activity but also suppressed endogenous ErbB-3 transcription in the ErbB-3 overexpressing cell line MRC-5VA. Overexpression of AP-2A resulted in a decreased proliferation rate and inhibitin of colony formation. Taken together, these data strongly support a role for the AP-2 gene family, in particular, AP-2gamma, in the control of ErbB-3 expression. Interference with the function of transcription factor AP-2 might provide a potential strategy for modulation of the malignant phenotype.

Beger M, Butz K, Denk C, et al.
Expression pattern of AP-2 transcription factors in cervical cancer cells and analysis of their influence on human papillomavirus oncogene transcription.
J Mol Med (Berl). 2001; 79(5-6):314-20 [PubMed] Related Publications
The AP-2 family of transcription factors consists of three known members, namely AP-2alpha, AP-2beta, and AP-2gamma. In experimental systems AP-2 factors possess tumor suppressor-like activities, and alterations in the AP-2 expression pattern have been described for some tumor entities. In addition, AP-2 has been implicated in the transcriptional control of human papillomaviruses (HPVs). We investigated here the expression pattern of AP-2alpha, AP-2beta, and AP-2gamma, as well as that of the cellular AP-2 target gene c-erbB-2, in a series of cervical cancer cell lines. In addition, we analyzed the influence of AP-2 factors on the activity of the HPV16 and HPV18 E6/E7 oncogene promoter. We found that, with the exception of HPV-negative C33A cells, all investigated cervical cancer cell lines expressed all three AP-2 family members, although at varying levels. No linear correlation between AP-2 and c-erbB-2 levels was observed. Although AP-2alpha, AP-2beta, and AP-2gamma can activate the c-erbB-2 promoter in reporter gene assays, they do not stimulate the HPV16 or HPV18 E6/E7 promoter. These results indicate that, although a rare event, loss of AP-2 expression occurs in cervical cancer cells. Moreover, AP-2alpha, AP-2beta, and AP-2gamma are neither sufficient nor required to activate the viral E6/E7 promoter.

Ropponen KM, Kellokoski JK, Pirinen RT, et al.
Expression of transcription factor AP-2 in colorectal adenomas and adenocarcinomas; comparison of immunohistochemistry and in situ hybridisation.
J Clin Pathol. 2001; 54(7):533-8 [PubMed] Free Access to Full Article Related Publications
AIMS: To investigate whether the three different AP-2 isoforms are expressed differently in colorectal adenomas and carcinomas.
METHODS: The study comprised 43 randomly selected patients diagnosed and treated at Kuopio University Hospital in 1996 for colorectal adenocarcinoma (n = 30) and colorectal adenoma (n = 13). The expression of AP-2alpha, AP-2beta, and AP-2gamma was analysed by immunohistochemistry (IHC) and the mRNA status of AP-2alpha was determined by in situ hybridisation (ISH) and confirmed by reverse transcription polymerase chain reaction (RT-PCR). AP-2 expression patterns were correlated with clinicopathological variables.
RESULTS: In adenomas and carcinomas, AP-2beta cytoplasmic positivity was higher than that of AP-2alpha or AP-2gamma. AP-2alpha expression was reduced in advanced Dukes's stage carcinomas. In high grade carcinomas, both AP-2alpha and AP-2gamma expression was reduced. ISH demonstrated increased AP-2alpha values in high grade carcinomas. Seven of 30 carcinoma specimens displayed a moderate or strong mRNA signal, despite being negative for AP-2alpha protein. RT-PCR from AP-2alpha mRNA and protein positive tumours confirmed that the positive signal in ISH originated from the exon 2 of TFAP2A.
CONCLUSIONS: AP-2alpha was reduced in advanced Dukes's stage adenocarcinomas. Together with reduced AP-2gamma expression in high grade carcinomas, this might contribute to tumour progression. The discrepancy between mRNA and protein expression suggests that post-transcriptional regulatory mechanisms might modify the availability of functional AP-2alpha protein in colorectal carcinoma.

Gershenwald JE, Sumner W, Calderone T, et al.
Dominant-negative transcription factor AP-2 augments SB-2 melanoma tumor growth in vivo.
Oncogene. 2001; 20(26):3363-75 [PubMed] Related Publications
We have previously demonstrated that the transition of melanoma to the metastatic phenotype is associated with a loss of expression of the transcription factor AP-2. To further investigate the role of AP-2 in the progression of human melanoma, we attempted to inactivate AP-2 in primary cutaneous SB-2 melanoma cells by using a dominant-negative AP-2, or AP-2B, gene. AP-2B is an alternatively spliced AP-2 variant capable of inhibiting AP-2 trans-activator function. Stable transfection of primary cutaneous melanoma SB-2 cells with the dominant-negative AP-2B gene was confirmed by RT--PCR and Northern blot analyses. Electromobility shift assay using nuclear extracts from these cell lines demonstrated decreased functional binding of AP-2B-transfected cells to the AP-2 consensus binding sequence compared with neo-transfected controls. In addition, CAT activity driven by a construct containing the AP-2 consensus binding sequence was downregulated in the AP-2B transfected cells, indicating AP-2 activity was quenched in the transfected cells. Orthotopic (subcutaneous) injection of the dominant-negative (AP-2B)-transfected cell lines into nude mice increased their tumorigenicity compared to control neo-transfected cells. The AP-2B-transfected cells displayed an increase in MMP-2 expression (by Northern blot) and MMP-2 activity (by zymography), which resulted in an increase in invasiveness through Matrigel-coated filters. The AP-2B-transfected tumors also displayed an increase in MMP-2 expression, microvessel density, and angiogenesis in vivo. These results demonstrate that inactivation of AP-2 contributes to the progression of melanoma, at least partially via deregulation of the MMP-2 gene.

Paggi MG, Bonetto F, Severino A, et al.
The retinoblastoma-related Rb2/p130 gene is an effector downstream of AP-2 during neural differentiation.
Oncogene. 2001; 20(20):2570-8 [PubMed] Related Publications
Rb2/p130, a member of the Retinoblastoma family of growth and tumour suppressor genes, is extensively implicated in the control of cell cycle and differentiation. The minimal promoter region of Rb2/p130 in T98G human glioblastoma cells was identified and its analysis revealed the presence of a KER1 palindromic sequence able to bind the transcription factor AP-2, a regulatory protein that plays a crucial role in ectodermal differentiation. This KER1 site interacted in vitro with AP-2, and AP-2 overexpression increased Rb2/p130 transcription and translation. We also found that rat PC12 pheochromocytoma cells, when induced to differentiate by NGF, displayed an increase of AP-2 protein levels and of Rb2/p130 transcription and protein levels. AP-2-transfected PC12 cells displayed enhanced transcription and translation of Rb2/p130 and of the cdk inhibitor p21(WAF1/CIP1), a gene known to be under the control of AP-2, but unable by itself to elicit PC12 differentiation. Overexpression of either AP-2 or Rb2/p130 elicited per se cell differentiation in the absence of NGF, while coexpression of AP-2B, a negative regulator of AP-2 transcriptional activity, inhibited only AP-2-induced differentiation. Altogether, these results indicate that Rb2/p130 is a critical effector of AP-2 in sustaining ectodermal differentiation.

Bar-Eli M
Gene regulation in melanoma progression by the AP-2 transcription factor.
Pigment Cell Res. 2001; 14(2):78-85 [PubMed] Related Publications
The molecular changes associated with the transition of melanoma cells from radial growth phase (RGP) to vertical growth phase [(VGP), metastatic phenotype] are not very well defined. We previously demonstrated that expression of the cell-surface adhesion molecule MCAM/MUC18 correlates directly with the metastatic potential of human melanoma cells. In addition, the progression of human melanoma towards the metastatic phenotype is associated with loss of expression of the tyrosine-kinase receptor c-KIT. In this review, I will summarize our recent studies demonstrating that the expression of both genes is regulated by the AP-2 transcription factor. Moreover, we have observed a loss of AP-2 expression in metastatic melanoma cells. Re-expression of AP-2 in the highly metastatic A375SM cells decreased their tumorigenicity and inhibited their metastatic potential in nude mice. MCAM/MUC18 mRNA and protein expression was significantly down-regulated while c-KIT expression was up-regulated in the AP-2-transfected cells. To further investigate the role of AP-2 in the progression of human melanoma, we attempted to inactivate AP-2 in primary cutaneous melanoma by using a dominant-negative AP-2, or the AP-2B gene. Expression of AP-2B in SB-2 cells augmented their tumorigenicity in nude mice, and upregulated MMP-2 expression and activity. As AP-2 also regulates other genes that are involved in the progression of human melanoma such as E-cadherin, p21/WAF-1, HER2/neu, Bcl-2, FAS/APO-1, IGF-R-1, VEGF and the thrombin receptor (PAR-1), we therefore propose that loss of AP-2 is a crucial event in the development of malignant melanoma. In addition, the transition of melanoma cells from RGP to VGP is also associated with over-expression of the transcription factors CREB and ATF-1. The notion that the balance between AP-2 and CREB/ATF-1 expression determines the progression of melanoma cells towards the metastatic phenotype will be discussed.

Perissi V, Menini N, Cottone E, et al.
AP-2 transcription factors in the regulation of ERBB2 gene transcription by oestrogen.
Oncogene. 2000; 19(2):280-8 [PubMed] Related Publications
Transcription of the ERBB2 oncogene is repressed by oestrogen in human breast cancer cells. We show that a 218 bp fragment of the human ERBB2 gene promoter is responsive to oestrogen in transient transfection in ZR75.1 and SKBR.3 cells when the oestrogen receptor is expressed. Deletion analysis of this fragment shows that a sequence located at the 5' end, which is known to mediate ERBB2 overexpression in breast cancer, is also responsible for the oestrogen response. This sequence binds AP-2 transcription factors and appears functionally identical to an element of the oestrogen-dependent enhancer described in the first intron of human ERBB2. We observed that oestrogen treatment down-regulates expression of AP-2 proteins but does not affect the DNA binding activity of AP-2. Constitutive expression of AP-2beta or AP-2gamma, but not AP-2alpha, abrogates the estrogenic repression. Our results demonstrate that AP-2 transcription factors are implicated in the oestrogenic regulation of ERBB2 gene expression and suggest a complex interplay involving the different AP-2 isoforms and other unidentified factors.

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