Gene Summary

Gene:TFAP2A; transcription factor AP-2 alpha
Aliases: AP-2, BOFS, AP2TF, TFAP2, AP-2alpha
Summary:The protein encoded by this gene is a transcription factor that binds the consensus sequence 5'-GCCNNNGGC-3'. The encoded protein functions as either a homodimer or as a heterodimer with similar family members. This protein activates the transcription of some genes while inhibiting the transcription of others. Defects in this gene are a cause of branchiooculofacial syndrome (BOFS). Three transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, Dec 2009]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:transcription factor AP-2-alpha
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 (5)

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: TFAP2A (cancer-related)

Lv J, Guo L, Wang JH, et al.
Biomarker identification and trans-regulatory network analyses in esophageal adenocarcinoma and Barrett's esophagus.
World J Gastroenterol. 2019; 25(2):233-244 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Esophageal adenocarcinoma (EAC) is an aggressive disease with high mortality and an overall 5-year survival rate of less than 20%. Barrett's esophagus (BE) is the only known precursor of EAC, and patients with BE have a persistent and excessive risk of EAC over time. Individuals with BE are up to 30-125 times more likely to develop EAC than the general population. Thus, early detection of EAC and BE could significantly improve the 5-year survival rate of EAC. Due to the limitations of endoscopic surveillance and the lack of clinical risk stratification strategies, molecular biomarkers should be considered and thoroughly investigated.
AIM: To explore the transcriptome changes in the progression from normal esophagus (NE) to BE and EAC.
METHODS: Two datasets from the Gene Expression Omnibus (GEO) in NCBI Database ( were retrieved and used as a training and a test dataset separately, since NE, BE, and EAC samples were included and the sample sizes were adequate. This study identified differentially expressed genes (DEGs) using the R/Bioconductor project and constructed trans-regulatory networks based on the Transcriptional Regulatory Element Database and Cytoscape software. Enrichment of Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) terms was identified using the Database for Annotation, Visualization, and Integrated Discovery (DAVID) Bioinformatics Resources. The diagnostic potential of certain DEGs was assessed in both datasets.
RESULTS: In the GSE1420 dataset, the number of up-regulated DEGs was larger than that of down-regulated DEGs when comparing EAC
CONCLUSION: After the construction and analyses of the trans-regulatory networks in EAC and BE, the results indicate that COL1A1 and MMP1 could be potential biomarkers for EAC and BE, respectively.

Wei L, He F, Zhang W, et al.
Bioinformatics analysis of microarray data to reveal the pathogenesis of diffuse intrinsic pontine glioma.
Biol Res. 2018; 51(1):26 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Diffuse intrinsic pontine glioma (DIPG) is the main cause of pediatric brain tumor death. This study was designed to identify key genes associated with DIPG.
METHODS: The gene expression profile GSE50021, which consisted of 35 pediatric DIPG samples and 10 normal brain samples, was downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified by limma package. Functional and pathway enrichment analyses were performed by the DAVID tool. Protein-protein interaction (PPI) network, and transcription factor (TF)-microRNA (miRNA)-target gene network were constructed using Cytoscape. Moreover, the expression levels of several genes were validated in human glioma cell line U251 and normal glia HEB cells through real-time polymerase chain reaction (PCR).
RESULTS: A total of 378 DEGs were screened (74 up-regulated and 304 down-regulated genes). In the PPI network, GRM1, HTR2A, GRM7 and GRM2 had higher degrees. Besides, GRM1 and HTR2A were significantly enriched in the neuroactive ligand-receptor interaction pathway, and calcium signaling pathway. In addition, TFAP2C was a significant down-regulated functional gene and hsa-miR-26b-5p had a higher degree in the TF-miRNA-target gene network. PCR analysis revealed that GRM7 and HTR2A were significantly downregulated while TFAP2C was upregulated in U251 cells compared with that in HEB cells (p < 0.001). GRM2 was not detected in cells.
CONCLUSIONS: GRM1 and HTR2A might function in DIPG through the neuroactive ligand-receptor interaction pathway and the calcium signaling pathway. Furthermore, the TFAP2C and hsa-miR-26b-5p might play important roles in the development and progression mechanisms of DIPG.

Hu J, Tan SK, Lim MGL, et al.
Identification of a Wells-Dawson polyoxometalate-based AP-2γ inhibitor with pro-apoptotic activity.
Biochem J. 2018; 475(11):1965-1977 [PubMed] Related Publications
AP-2 gamma (AP-2γ) is a transcription factor that plays pivotal roles in breast cancer biology. To search for small molecule inhibitors of AP-2γ, we performed a high-throughput fluorescence anisotropy screen and identified a polyoxometalate compound with Wells-Dawson structure K

Xiong G, Huang H, Feng M, et al.
MiR-10a-5p targets TFAP2C to promote gemcitabine resistance in pancreatic ductal adenocarcinoma.
J Exp Clin Cancer Res. 2018; 37(1):76 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: By regulating target genes, microRNAs play essential roles in carcinogenesis and drug resistance in human pancreatic ductal adenocarcinoma (PDAC). Previous studies have shown that microRNA-10a-5p (miR-10a-5p) is overexpressed in PDAC and acts as an oncogene to promote the metastatic behavior of PDAC cells. However, the role of miR-10a-5p in PDAC chemoresistance remains unclear.
METHODS: The effects of miR-10a-5p on biological behaviors were analyzed. MiR-10a-5p and TFAP2C levels in tissues were detected, and the clinical value was evaluated.
RESULTS: We found that miR-10a-5p is up-regulated in gemcitabine-resistant PDAC cells and enhances PDAC cell gemcitabine resistance in vitro and vivo. Meanwhile, we also determined that miR-10a-5p promotes the migratory and invasive ability of PDAC cells. Next, we confirmed that transcription factor activating protein 2 gamma (TFAP2C) is a target of miR-10a-5p, and TFAP2C overexpression resensitizes PDAC cells to gemcitabine, which is initiated by miR-10a-5p. Further studies revealed that TFAP2C also decreased PDAC cell migration and invasion capability. Finally, survival analysis demonstrated that high miR-10a-5p expression levels and low TFAP2C expression levels were both independent adverse prognostic factors in patients with PDAC.
CONCLUSION: Together, these results indicate that miR-10a-5p/TFAP2C may be new therapeutic target and prognostic marker in PDAC.

Wang X, Sun D, Tai J, et al.
TFAP2C promotes stemness and chemotherapeutic resistance in colorectal cancer via inactivating hippo signaling pathway.
J Exp Clin Cancer Res. 2018; 37(1):27 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Aberrant expression of transcription Factor AP-2 Gamma (TFAP2C) has been reported to be implicated in malignant process of many cancers. The purpose of this study is to investigate the clinical significance and biological roles of TFAP2C in colorectal cancer (CRC).
METHODS: TFAP2C expression was evaluated by real-time PCR, Western blot and immunohistochemistry (IHC) respectively in clinical CRC tissues. Statistical analysis was performed to explore the correlation between TFAP2C expression and clinicopathological features, and overall and progression-free survival in CRC patients. In vitro and in vivo assays were performed to assess the biological roles of TFAP2C in CRC cells. Western blot, luciferase and Chromatin immunoprecipitation (ChIP) assays were used to identify the underlying pathway mediating the biological roles of TFAP2C in CRC.
RESULTS: TFAP2C is robustly upregulated in CRC tissues and cells, and high expression of TFAP2C correlates with advanced clinicopathological features, poor prognosis and disease progression in CRC patients. Furthermore, upregulating TFAP2C enhances spheroids formation ability, the fraction of SP cells, expression of stem cell factors and the mitochondrial potential, and reduces the apoptosis induced by 5-fluorouracil in colorectal cancer cells in vitro, and promotes stemness and chemoresistance of CRC cells in vivo; while silencing TFAP2C yields an opposite effect. Importantly, downregulation of TFAP2C dramatically restores chemotherapeutic sensitivity of CRC cells to 5-FU in vivo. Our results further demonstrate that TFAP2C promotes stemness and chemoresistance of CRC cells to 5-FU by inhibiting Hippo signaling via transcriptionally upregulating ROCK1 and ROCK2 in CRC cells.
CONCLUSION: Our findings indicate that TFAP2C may serve as a novel prognostic factor in CRC patients, and a therapeutic target for the treatment of CRC, suggesting that silencing TFAP2C in combination with 5-FU may be an effective therapeutic strategy to improve survival in CRC patients.

Vastrad B, Vastrad C, Tengli A, Iliger S
Identification of differentially expressed genes regulated by molecular signature in breast cancer-associated fibroblasts by bioinformatics analysis.
Arch Gynecol Obstet. 2018; 297(1):161-183 [PubMed] Related Publications
OBJECTIVE: Breast cancer is a severe risk to public health and has adequately convoluted pathogenesis. Therefore, the description of key molecular markers and pathways is of much importance for clarifying the molecular mechanism of breast cancer-associated fibroblasts initiation and progression. Breast cancer-associated fibroblasts gene expression dataset was downloaded from Gene Expression Omnibus database.
METHODS: A total of nine samples, including three normal fibroblasts, three granulin-stimulated fibroblasts and three cancer-associated fibroblasts samples, were used to identify differentially expressed genes (DEGs) between normal fibroblasts, granulin-stimulated fibroblasts and cancer-associated fibroblasts samples. The gene ontology (GO) and pathway enrichment analysis was performed, and protein-protein interaction (PPI) network of the DEGs was constructed by NetworkAnalyst software.
RESULTS: Totally, 190 DEGs were identified, including 66 up-regulated and 124 down-regulated genes. GO analysis results showed that up-regulated DEGs were significantly enriched in biological processes (BP), including cell-cell signalling and negative regulation of cell proliferation; molecular function (MF), including insulin-like growth factor II binding and insulin-like growth factor I binding; cellular component (CC), including insulin-like growth factor binding protein complex and integral component of plasma membrane; the down-regulated DEGs were significantly enriched in BP, including cell adhesion and extracellular matrix organization; MF, including N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase activity and calcium ion binding; CC, including extracellular space and extracellular matrix. WIKIPATHWAYS analysis showed the up-regulated DEGs were enriched in myometrial relaxation and contraction pathways. WIKIPATHWAYS, REACTOME, PID_NCI and KEGG pathway analysis showed the down-regulated DEGs were enriched endochondral ossification, TGF beta signalling pathway, integrin cell surface interactions, beta1 integrin cell surface interactions, malaria and glycosaminoglycan biosynthesis-chondroitin sulfate/dermatan sulphate. The top 5 up-regulated hub genes, CDKN2A, MME, PBX1, IGFBP3, and TFAP2C and top 5 down-regulated hub genes VCAM1, KRT18, TGM2, ACTA2, and STAMBP were identified from the PPI network, and subnetworks revealed these genes were involved in significant pathways, including myometrial relaxation and contraction pathways, integrin cell surface interactions, beta1 integrin cell surface interaction. Besides, the target hsa-mirs for DEGs were identified. hsa-mir-759, hsa-mir-4446-5p, hsa-mir-219a-1-3p and hsa-mir-26a-5p were important miRNAs in this study.
CONCLUSIONS: We pinpoint important key genes and pathways closely related with breast cancer-associated fibroblasts initiation and progression by a series of bioinformatics analysis on DEGs. These screened genes and pathways provided for a more detailed molecular mechanism underlying breast cancer-associated fibroblasts occurrence and progression, holding promise for acting as molecular markers and probable therapeutic targets.

Liu Q, Kulak MV, Borcherding N, et al.
A novel HER2 gene body enhancer contributes to HER2 expression.
Oncogene. 2018; 37(5):687-694 [PubMed] Free Access to Full Article Related Publications
The transcriptional regulation of the human epidermal growth factor receptor-2 (HER2) contributes to an enhanced HER2 expression in HER2-positive breast cancers with HER2 gene amplification and HER2-low or HER2-negative breast cancers following radiotherapy or endocrine therapy, and this drives tumorigenesis and the resistance to therapy. Epigenetic mechanisms are critical for transcription regulation, however, such mechanisms in the transcription regulation of HER2 are limited to the involvement of tri-methylated histone 3 lysine 4 (H3K4me3) and acetylated histone 3 lysine 9 (H3K9ac) at the HER2 promoter region. Here, we report the identification of a novel enhancer in the HER2 3' gene body, which we have termed HER2 gene body enhancer (HGE). The HGE starts from the 3' end of intron 19 and extends into intron 22, possesses enhancer histone modification marks in specific cells and enhances the transcriptional activity of the HER2 promoters. We also found that TFAP2C, a known regulator of HER2, binds to HGE and is required for its enhancer function and that DNA methylation in the HGE region inhibits the histone modifications characterizing enhancer and is inversely correlated with HER2 expression in breast cancer samples. The identification of this novel enhancer sheds a light on the roles of epigenetic mechanisms in HER2 transcription, in both HER2-positive breast cancer samples and individuals with HER2-low or HER2-negative breast cancers undergoing radiotherapy or endocrine therapy.

Chang TH, Tsai MF, Gow CH, et al.
Upregulation of microRNA-137 expression by Slug promotes tumor invasion and metastasis of non-small cell lung cancer cells through suppression of TFAP2C.
Cancer Lett. 2017; 402:190-202 [PubMed] Related Publications
The epithelial-mesenchymal transition (EMT) regulator, Slug, plays multifaceted roles in controlling lung cancer progression, but its downstream targets and mechanisms in promoting lung cancer progression have not been well defined. In particular, the miRNAs downstream of Slug in non-small cell lung cancer (NSCLC) remain undetermined. Here, we report that miR-137 is downstream of the EMT regulator, Slug, in lung cancer cells. Slug binds directly to the E-box of the miR-137 promoter and up-regulates its expression in lung cancer cells. Knockdown of miR-137 abolished Slug-induced cancer invasion and migration, whereas upregulation of miR-137 was found to trigger lung cancer cell invasion and progression by direct suppressing TFAP2C (transcription factor AP-2 gamma). Clinical data showed that lung adenocarcinoma patients with low-level expression of Slug and miR-137 but high-level expression of TFAP2C experienced significantly better survival. miR-137 is a Slug-induced miRNA that relays the pro-metastatic effects of Slug by targeting TFAP2C. Our findings add new components to the Slug-mediated regulatory network in lung cancer, and suggest that Slug, miR-137, and TFAP2C may be useful prognostic markers in lung adenocarcinoma.

Kim W, Kim E, Lee S, et al.
TFAP2C-mediated upregulation of TGFBR1 promotes lung tumorigenesis and epithelial-mesenchymal transition.
Exp Mol Med. 2016; 48(11):e273 [PubMed] Free Access to Full Article Related Publications
TFAP2C (transcription factor-activating enhancer-binding protein 2C) expression has been positively correlated with poor prognosis in patients with certain types of cancer, but the mechanisms underlying TFAP2C-mediated tumorigenesis in non-small-cell lung cancer (NSCLC) are still unknown. We previously performed a microarray analysis to identify TFAP2C regulation genes, and TGFBR1 (transforming growth factor-β receptor type 1) was found to be upregulated by TFAP2C. We observed that TFAP2C or TGFBR1 overexpression led to oncogenic properties, such as cell viability, proliferation and cell cycle progression. TGFBR1 upregulation induced by TFAP2C also promoted cell motility and migration, leading to malignant development. We also found that PAK1 (p21 protein (Cdc42/Rac)-activated kinase 1) signaling was involved in TFAP2C/TGFBR1-induced tumorigenesis. These results were confirmed by an in vivo xenograft model and patient tissue samples. This study shows that TFAP2C promoted tumor progression by upregulation of TGFBR1 and consequent activation of PAK1 signaling.

Jeselsohn R, Barry WT, Migliaccio I, et al.
TransCONFIRM: Identification of a Genetic Signature of Response to Fulvestrant in Advanced Hormone Receptor-Positive Breast Cancer.
Clin Cancer Res. 2016; 22(23):5755-5764 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Fulvestrant is an estrogen receptor (ER) antagonist and an approved treatment for metastatic estrogen receptor-positive (ER
EXPERIMENTAL DESIGN: Primary tumor samples from 134 patients enrolled in the phase III CONFIRM study of patients with metastatic ER
RESULTS: Pathway analysis demonstrated that increased EGF pathway and FOXA1 transcriptional signaling is associated with decreased response to fulvestrant. Using a multivariate Cox model, we identified a novel set of 37 genes with an expression that is independently associated with progression-free survival (PFS). TFAP2C, a known regulator of ER activity, was ranked second in this gene set, and high expression was associated with a decreased response to fulvestrant. The negative predictive value of TFAP2C expression at the protein level was confirmed by IHC.
CONCLUSIONS: We identified biologic pathways and a novel gene signature in primary ER

Kang J, Kim W, Lee S, et al.
TFAP2C promotes lung tumorigenesis and aggressiveness through miR-183- and miR-33a-mediated cell cycle regulation.
Oncogene. 2017; 36(11):1585-1596 [PubMed] Related Publications
Non-small cell lung cancer (NSCLC) remains one of the leading causes of death worldwide, and thus new molecular targets need to be identified to improve treatment efficacy. Although epidermal growth factor receptor (EGFR)/KRAS mutation-driven lung tumorigenesis is well understood, the mechanism of EGFR/KRAS-independent signal activation remains elusive. Enhanced TFAP2C (transcription factor activating enhancer-binding protein 2C) expression is associated with poor prognosis in some types of cancer patients, but little is known of its relation with the pathogenesis of lung cancer. In the present study, we found that TFAP2C overexpression was associated with cell cycle activation and NSCLC cell tumorigenesis. Interestingly, TFAP2C blocked AKAP12-mediated cyclin D1 inhibition by inducing the overexpression of oncogenic microRNA (miRNA)-183 and simultaneously activated cyclin-dependent kinase 6-mediated cell cycle progression by downregulating tumor-suppressive miRNA-33a. In a mouse xenograft model, TFAP2C promoted lung tumorigenesis and disease aggressiveness via the miR-183 and miR-33a pathways. The study provides a mechanism of mitogenic and oncogenic signaling via two functionally opposed miRNAs and suggests that TFAP2C-induced cell cycle hyperactivation contributes to lung tumorigenesis.

Lin CY, Chao A, Wang TH, et al.
Nucleophosmin/B23 is a negative regulator of estrogen receptor α expression via AP2γ in endometrial cancer cells.
Oncotarget. 2016; 7(37):60038-60052 [PubMed] Free Access to Full Article Related Publications
Endometrial cancers expressing estrogen and progesterone receptors respond to hormonal therapy. The disappearance of steroid hormone receptor expression is common in patients with recurrent disease, ultimately hampering the clinical utility of hormonal therapy. Here, we demonstrate for the first time that nucleophosmin (NPM1/B23) suppression can restore the expression of estrogen receptor α (ESR1/ERα) in endometrial cancer cells. Mechanistically, B23 and activator protein-2γ (TFAP2C/AP2γ) form a complex that acts as a transcriptional repressor of ERα. Our results indicate that B23 or AP2γ knockdown can restore ERα levels and activate ERα-regulated genes (e.g., cathepsin D, EBAG9, and TFF1/pS2). Moreover, AP2γ knockdown in a xenograft model sensitizes endometrial cancer cells to megesterol acetate through the upregulation of ERα expression. An increased immunohistochemical expression of AP2γ is an adverse prognostic factor in endometrial cancer. In summary, B23 and AP2γ may act in combination to suppress ERα expression in endometrial cancer cells. The inhibition of B23 or AP2γ can restore ERα expression and can serve as a potential strategy for sensitizing hormone-refractory endometrial cancers to endocrine therapy.

Nettersheim D, Heimsoeth A, Jostes S, et al.
SOX2 is essential for in vivo reprogramming of seminoma-like TCam-2 cells to an embryonal carcinoma-like fate.
Oncotarget. 2016; 7(30):47095-47110 [PubMed] Free Access to Full Article Related Publications
Type II germ cell cancers (GCC) are divided into seminomas, which are highly similar to primordial germ cells and embryonal carcinomas (EC), often described as malignant counterparts to embryonic stem cells.Previously, we demonstrated that the development of GCCs is a highly plastic process and strongly influenced by the microenvironment. While orthotopic transplantation into the testis promotes seminomatous growth of the seminoma-like cell line TCam-2, ectopic xenotransplantation into the flank initiates reprogramming into an EC-like fate.During this reprogramming, BMP signaling is inhibited, leading to induction of NODAL signaling, upregulation of pluripotency factors and downregulation of seminoma markers, like SOX17. The pluripotency factor and EC-marker SOX2 is strongly induced.Here, we adressed the molecular role of SOX2 in this reprogramming. Using CRISPR/Cas9-mediated genome-editing, we established SOX2-deficient TCam-2 cells. Xenografting of SOX2-deficient cells into the flank of nude mice resulted in maintenance of a seminoma-like fate, indicated by the histology and expression of OCT3/4, SOX17, TFAP2C, PRDM1 and PRAME. In SOX2-deficient cells, BMP signaling is inhibited, but NODAL signaling is not activated. Thus, SOX2 appears to be downstream of BMP signaling but upstream of NODAL activation. So, SOX2 is an essential factor in acquiring an EC-like cell fate from seminomas.A small population of differentiated cells was identified resembling a mixed non-seminoma. Analyses of these cells revealed downregulation of the pluripotency and seminoma markers OCT3/4, SOX17, PRDM1 and TFAP2C. In contrast, the pioneer factor FOXA2 and its target genes were upregulated, suggesting that FOXA2 might play an important role in induction of non-seminomatous differentiation.

De Andrade JP, Park JM, Gu VW, et al.
EGFR Is Regulated by TFAP2C in Luminal Breast Cancer and Is a Target for Vandetanib.
Mol Cancer Ther. 2016; 15(3):503-11 [PubMed] Free Access to Full Article Related Publications
Expression of TFAP2C in luminal breast cancer is associated with reduced survival and hormone resistance, partially explained through regulation of RET. TFAP2C also regulates EGFR in HER2 breast cancer. We sought to elucidate the regulation and functional role of EGFR in luminal breast cancer. We used gene knockdown (KD) and treatment with a tyrosine kinase inhibitor (TKI) in cell lines and primary cancer isolates to determine the role of RET and EGFR in regulation of p-ERK and tumorigenesis. KD of TFAP2C decreased expression of EGFR in a panel of luminal breast cancers, and chromatin immunoprecipitation sequencing (ChIP-seq) confirmed that TFAP2C targets the EGFR gene. Stable KD of TFAP2C significantly decreased cell proliferation and tumor growth, mediated in part through EGFR. While KD of RET or EGFR reduced proliferation (31% and 34%, P < 0.01), combined KD reduced proliferation greater than either alone (52% reduction, P < 0.01). The effect of the TKI vandetanib on proliferation and tumor growth response of MCF-7 cells was dependent upon expression of TFAP2C, and dual KD of RET and EGFR eliminated the effects of vandetanib. The response of primary luminal breast cancers to TKIs assessed by ERK activation established a correlation with expression of RET and EGFR. We conclude that TFAP2C regulates EGFR in luminal breast cancer. Response to vandetanib was mediated through the TFAP2C target genes EGFR and RET. Vandetanib may provide a therapeutic effect in luminal breast cancer, and RET and EGFR can serve as molecular markers for response.

Rajpert-De Meyts E, Nielsen JE, Skakkebaek NE, Almstrup K
Diagnostic markers for germ cell neoplasms: from placental-like alkaline phosphatase to micro-RNAs.
Folia Histochem Cytobiol. 2015; 53(3):177-88 [PubMed] Related Publications
This concise review summarises tissue and serum markers useful for differential diagnosis of germ cell tumours (GCT), with focus on the most common testicular GCT (TGCT). GCT are characterised by phenotypic heterogeneity due to largely retained embryonic pluripotency and aberrant somatic differentiation. TGCT that occur in young men are divided into two main types, seminoma and nonseminoma, both derived from a pre-invasive germ cell neoplasia in situ (GCNIS), which originates from transformed foetal gonocytes. In severely dysgenetic gonads, a GCNIS-resembling lesion is called gonadoblastoma. GCT occur rarely in young children (infantile GCT) in whom the pathogenesis is different (no GCNIS/gonadoblastoma stage) but the histopathological features are similar to the adult GCT. The rare spermatocytic tumour of older men is derived from post-pubertal spermatogonia that clonally expand due to gain-of function mutations in survival-promoting genes (e.g. FGFR3, HRAS), thus this tumour has a different expression profile than GCNIS-derived TGCT. Clinically most informative immunohistochemical markers for GCT, except teratoma, are genes expressed in primordial germ cells/gonocytes and embryonic pluripotency-related factors, such as placental-like alkaline phosphatase (PLAP), OCT4 (POU5F1), NANOG, AP-2γ (TFAP2C) and LIN28, which are not expressed in normal adult germ cells. Some of these markers can also be used for immunocytochemistry to detect GCNIS or incipient tumours in semen samples. Gene expression in GCT is regulated in part by DNA and histone modifications, and the epigenetic profile of these tumours is characterised by genome-wide demethylation, except nonseminomas. In addition, a recently discovered mechanism of post-genomic gene expression regulation involves small non-coding RNAs, predominantly micro-RNA (miR). Testicular GCT display micro-RNA profiles similar to embryonic stem cells. Targeted miRNA-based blood tests for miR-371-3 and miR-367 clusters are currently under development and hold a great promise for the future. In some patients miR-based tests may be even more sensitive than the classical serum tumour markers, β -chorio-gonadotrophin (β-hCG), α-fetoprotein (AFP) and lactate dehydrogenase (LDH), which are currently used in the clinic. In summary, research advances have provided clinicians with a panel of molecular markers, which allow specific diagnosis of various subtypes of GCT and are very useful for early detection at the precursor stage and for monitoring of patients during the follow-up.

Park JM, Wu T, Cyr AR, et al.
The role of Tcfap2c in tumorigenesis and cancer growth in an activated Neu model of mammary carcinogenesis.
Oncogene. 2015; 34(50):6105-14 [PubMed] Free Access to Full Article Related Publications
TFAP2C/AP-2γ influences development of the mammary gland and regulates patterns of gene expression in luminal and HER2-amplified breast cancer. The roles of TFAP2C in mammary gland tumorigenesis and in pathways critical to cancer progression remain poorly understood. To gain greater insight into oncogenic mechanisms regulated by TFAP2C, we examined mammary tumorigenesis in MMTV-Neu transgenic female mice with or without conditional knockout (KO) of Tcfap2c, the mouse homolog of TFAP2C. Loss of Tcfap2c increased the latency of tumorigenesis and tumors that formed demonstrated reduced proliferative index and increased apoptosis. In addition, tumors formed in Tcfap2c KO animals had a significant reduction in Egfr levels without a change in the expression of the Neu oncogene. The MMneu-flAP2C cell line was established from tumor tissue derived from MMTV-Neu/Tcfap2c(L/L) control animals and parallel cell lines with and without expression of Tcfap2c were created by transduction with adenovirus-empty and adenovirus-Cre, respectively. KO of Tcfap2c in vitro reduced activated phosphorylated-Erk, decreased cell viability, repressed tumor growth and was associated with attenuation of Egfr expression. Chromatin immunoprecipitation and direct sequencing and expression analysis confirmed that Egfr was a Tcfap2c target gene in murine, as well as human, mammary carcinoma cells. Furthermore, decreased viability of mammary cancer cells was directly related to Egfr functional blockade. We conclude that TFAP2C regulates tumorigenesis, cell growth and survival in HER2-amplified breast cancer through transcriptional regulation of EGFR. The findings have important implications for targeting the EGFR pathway in breast cancer.

Gao SL, Wang LZ, Liu HY, et al.
miR-200a inhibits tumor proliferation by targeting AP-2γ in neuroblastoma cells.
Asian Pac J Cancer Prev. 2014; 15(11):4671-6 [PubMed] Related Publications
BACKGROUND: MicroRNA-200a (miR-200a) has been reported to regulate tumour progression in several tumours but little is known about its role in neuroblastoma. Our aim was to investigate the potential role and mechanism of miR-200a in neuroblastomas.
MATERIALS AND METHODS: Expression levels of miR-200a in tissues were determined using RT-PCR. The effect of miR-200a and shAP-2γ on cell viability was evaluated using MTS assays, and target protein expression was determined using Western blotting and RT-PCR. Luciferase reporter plasmids were constructed to confirm direct targeting. RESULTS were reported as mean±S.E.M and differences were tested for significance using the 2-tailed Students t-test.
RESULTS: We determined that miR-200a expression was significantly lower in neuroblastoma tumors than the adjacent non-cancer tissue. Over-expression of miR-200 are reduced cell viability in neuroblastoma cells and inhibited tumor growth in mouse xenografts. We identified AP-2γ as a novel target for miR-200a in neuroblastoma cells. Thus miR-200a targets the 3'UTR of AP-2γ and inhibits its mRNA and protein expression. Furthermore, our result showed that shRNA knockdown of AP-2γ in neuroblastoma cells results in significant inhibit of cell proliferation and tumor growth in vitro, supporting an oncogenic role of AP-2γ in neuroblastoma.
CONCLUSIONS: Our study revealed that miR-200a is a candidate tumor suppressor in neuroblastoma, through direct targeting of AP-2γ. These findings re-enforce the proposal of AP-2γ as a therapeutic target in neuroblastoma.

Bogachek MV, Chen Y, Kulak MV, et al.
Sumoylation pathway is required to maintain the basal breast cancer subtype.
Cancer Cell. 2014; 25(6):748-61 [PubMed] Free Access to Full Article Related Publications
The TFAP2C/AP-2γ transcription factor regulates luminal breast cancer genes, and loss of TFAP2C induces epithelial-mesenchymal transition. By contrast, the highly homologous family member, TFAP2A, lacks transcriptional activity at luminal gene promoters. A detailed structure-function analysis identified that sumoylation of TFAP2A blocks its ability to induce the expression of luminal genes. Disruption of the sumoylation pathway by knockdown of sumoylation enzymes, mutation of the SUMO-target lysine of TFAP2A, or treatment with sumoylation inhibitors induced a basal-to-luminal transition, which was dependent on TFAP2A. Sumoylation inhibitors cleared the CD44(+/hi)/CD24(-/low) cell population characterizing basal cancers and inhibited tumor outgrowth of basal cancer xenografts. These findings establish a critical role for sumoylation in regulating the transcriptional mechanisms that maintain the basal cancer phenotype.

Jørgensen A, Young J, Nielsen JE, et al.
Hanging drop cultures of human testis and testis cancer samples: a model used to investigate activin treatment effects in a preserved niche.
Br J Cancer. 2014; 110(10):2604-14 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Testicular germ cell tumours of young adults, seminoma or non-seminomas, are preceded by a pre-invasive precursor, carcinoma in situ (CIS), understood to arise through differentiation arrest of embryonic germ cells. Knowledge about the malignant transformation of germ cells is currently limited by the lack of experimental models. The aim of this study was to establish an experimental tissue culture model to maintain normal and malignant germ cells within their niche and allow investigation of treatment effects.
METHODS: Human testis and testis cancer specimens from orchidectomies were cultured in 'hanging drops' and effects of activin A and follistatin treatment were investigated in seminoma cultures.
RESULTS: Testis fragments with normal spermatogenesis or CIS cells were cultured for 14 days with sustained proliferation of germ cells and CIS cells and without increased apoptosis. Seminoma cultures survived 7 days, with proliferating cells detectable during the first 5 days. Activin A treatment significantly reduced KIT transcript and protein levels in seminoma cultures, thereby demonstrating a specific treatment response.
CONCLUSIONS: Hanging drop cultures of human testis and testis cancer samples can be employed to delineate mechanisms governing growth of normal, CIS and tumorigenic germ cells retained within their niche.

Cyr AR, Kulak MV, Park JM, et al.
TFAP2C governs the luminal epithelial phenotype in mammary development and carcinogenesis.
Oncogene. 2015; 34(4):436-44 [PubMed] Free Access to Full Article Related Publications
Molecular subtypes of breast cancer are characterized by distinct patterns of gene expression that are predictive of outcome and response to therapy. The luminal breast cancer subtypes are defined by the expression of estrogen receptor-alpha (ERα)-associated genes, many of which are directly responsive to the transcription factor activator protein 2C (TFAP2C). TFAP2C participates in a gene regulatory network controlling cell growth and differentiation during ectodermal development and regulating ESR1/ERα and other luminal cell-associated genes in breast cancer. TFAP2C has been established as a prognostic factor in human breast cancer, however, its role in the establishment and maintenance of the luminal cell phenotype during carcinogenesis and mammary gland development have remained elusive. Herein, we demonstrate a critical role for TFAP2C in maintaining the luminal phenotype in human breast cancer and in influencing the luminal cell phenotype during normal mammary development. Knockdown of TFAP2C in luminal breast carcinoma cells induced epithelial-mesenchymal transition with morphological and phenotypic changes characterized by a loss of luminal-associated gene expression and a concomitant gain of basal-associated gene expression. Conditional knockout of the mouse homolog of TFAP2C, Tcfap2c, in mouse mammary epithelium driven by MMTV-Cre promoted aberrant growth of the mammary tree leading to a reduction in the CD24(hi)/CD49f(mid) luminal cell population and concomitant gain of the CD24(mid)/CD49f(hi) basal cell population at maturity. Our results establish TFAP2C as a key transcriptional regulator for maintaining the luminal phenotype in human breast carcinoma. Furthermore, Tcfap2c influences development of the luminal cell type during mammary development. The data suggest that TFAP2C has an important role in regulated luminal-specific genes and may be a viable therapeutic target in breast cancer.

Kang HJ, Lee MH, Kang HL, et al.
Differential regulation of estrogen receptor α expression in breast cancer cells by metastasis-associated protein 1.
Cancer Res. 2014; 74(5):1484-94 [PubMed] Related Publications
Metastasis-associated protein 1 (MTA1) is a component of the nucleosome remodeling and histone deacetylase (HDAC) complex, which plays an important role in progression of breast cancer. Although MTA1 is known as a repressor of the transactivation function of estrogen receptor α (ERα), its involvement in the epigenetic control of transcription of the ERα gene ESR1 has not been studied. Here, we show that silencing of MTA1 reduced the level of expression of ERα in ERα-positive cells but increased it in ERα-negative cells. In both MCF7 and MDA-MB-231, MTA1 was recruited to the region +146 to +461 bp downstream of the transcription start site of ESR1 (ERpro315). Proteomics analysis of the MTA1 complex that was pulled down by an oligonucleotide encoding ERpro315 revealed that the transcription factor AP-2γ (TFAP2C) and the IFN-γ-inducible protein 16 (IFI16) were components of the complex. Interestingly, in MCF7, TFAP2C activated the reporter encoding ERpro315 and the level of ERα mRNA. By contrast, in MDA-MB-231, IFI16 repressed the promoter activity and silencing of MTA1 increased expression of ERα. Importantly, class II HDACs are involved in the MTA1-mediated differential regulation of ERα. Finally, an MDA-MB-231-derived cell line that stably expressed shIFI16 or shMTA1 was more susceptible to tamoxifen-induced growth inhibition in in vitro and in vivo experiments. Taken together, our findings suggest that the MTA1-TFAP2C or the MTA1-IFI16 complex may contribute to the epigenetic regulation of ESR1 expression in breast cancer and may determine the chemosensitivity of tumors to tamoxifen therapy in patients with breast cancer.

Spanheimer PM, Cyr AR, Gillum MP, et al.
Distinct pathways regulated by RET and estrogen receptor in luminal breast cancer demonstrate the biological basis for combination therapy.
Ann Surg. 2014; 259(4):793-9 [PubMed] Free Access to Full Article Related Publications
OBJECTIVE: We investigated directed therapy based on TFAP2C-regulated pathways to inform new therapeutic approaches for treatment of luminal breast cancer.
BACKGROUND: TFAP2C regulates the expression of genes characterizing the luminal phenotype including ESR1 and RET, but pathway cross talk and potential for distinct elements have not been characterized.
METHODS: Activation of extracellular signal-regulated kinases (ERK) and AKT was assessed using phosphorylation-specific Western blot. Cell proliferation was measured with MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] after siRNA (small interfering RNA) gene knockdown or drug treatment. Cell cycle, Ki-67, and cleaved caspase 3 were measured by fluorescence-activated cell sorting. Tumorigenesis was assessed in mice xenografts.
RESULTS: Knockdown of TFAP2C or RET inhibited GDNF (glial cell line-derived neurotrophic factor)-mediated activation of ERK and AKT in MCF-7 cells. Similarly, sunitinib, a small-molecule inhibitor of RET, blocked GDNF-mediated activation of ERK and AKT. Inhibition of RET either by gene knockdown or by treatment with sunitinib or vandetanib reduced RET-dependent growth of luminal breast cancer cells. Interestingly, knockdown of TFAP2C, which controls both ER (estrogen receptor) and RET, demonstrated a greater effect on cell growth than either RET or ER alone. Parallel experiments using treatment with tamoxifen and sunitinib confirmed the increased effectiveness of dual inhibition of the ER and RET pathways in regulating cell growth. Whereas targeting the ER pathway altered cell proliferation, as measured by Ki-67 and S-phase, anti-RET primarily increased apoptosis, as demonstrated by cleaved caspase 3 and increased TUNEL (terminal deoxyneucleotidyl transferase dUTP nick end labeling) expression in xenografts.
CONCLUSIONS: ER and RET primarily function through distinct pathways regulating proliferation and cell survival, respectively. The findings inform a therapeutic approach based on combination therapy with antiestrogen and anti-RET in luminal breast cancer.

Lal G, Contreras PG, Kulak M, et al.
Human Melanoma cells over-express extracellular matrix 1 (ECM1) which is regulated by TFAP2C.
PLoS One. 2013; 8(9):e73953 [PubMed] Free Access to Full Article Related Publications
Extracellular matrix 1 (ECM1) is over-expressed in multiple epithelial malignancies. However, knowledge regarding the expression of ECM1 in melanomas and the mechanisms of ECM1 regulation is limited. In this study, we found that ECM1 is over-expressed in several melanoma cell lines, when compared to primary melanocytes, and furthermore, that ECM1 expression paralleled that of TFAP2C levels in multiple cell lines. Knockdown of TFAP2C in the A375 cell line with siRNA led to a reduction in ECM1 expression, and upregulation of TFAP2C with adenoviral vectors in the WM793 cell line resulted in ECM1 upregulation. Utilizing 5' RACE to identify transcription start sites (TSS) and luciferase reporter assays in the ECM1-overexpressing A375 cell line, we identified the minimal promoter region of human ECM1 and demonstrate that an approximately 100bp fragment upstream of the TSS containing a TATA box and binding sites for AP1, SP1 and Ets is sufficient for promoter activity. Chromatin immunoprecipitation and direct sequencing (ChIP-seq) for TFAP2C in the A375 cell line identified an AP2 regulatory region in the promoter of the ECM1 gene. Gelshift assays further confirmed binding of TFAP2C to this site. ECM1 knockdown reduces melanoma cell attachment and is consistent with findings that ECM1 overexpression has been associated with a poor prognosis. Our investigations show an as yet unrecognized role for TFAP2C in melanoma via its regulation of ECM1.

Spanheimer PM, Askeland RW, Kulak MV, et al.
High TFAP2C/low CD44 expression is associated with an increased rate of pathologic complete response following neoadjuvant chemotherapy in breast cancer.
J Surg Res. 2013; 184(1):519-25 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: In luminal breast cancer cell lines, TFAP2C regulates expression of key genes in the estrogen receptor-associated cluster and represses basal-associated genes including CD44. We examined the effect of TFAP2C overexpression in a basal cell line and characterized the expression of TFAP2C and CD44 in breast cancer specimens to determine if expression was associated with clinical response.
METHODS: MDA-MB-231 breast cancer cells were treated with a TFAP2C-containing plasmid and evaluated for effects on CD44 expression. Pretreatment biopsy cores from patients receiving neoadjuvant chemotherapy for breast cancer were evaluated for TFAP2A, p53, TFAP2C, and CD44 expression by immunohistochemistry.
RESULTS: Overexpression of TFAP2C in MDA-MB-231 cells resulted in decreased expression of CD44 mRNA and protein, P < 0.05. A pathologic complete response (pCR) following neoadjuvant chemotherapy was achieved in 17% of patients (4/23). Average expression for TFAP2C by immunohistochemistry in patients with a pCR was 93%, compared with 46% in patients with residual disease, P = 0.016; and in tumors that stained at ≥80% for TFAP2C, 4 of 9 (44%) achieved pCR, compared with 0 of 14 below 80%, P = 0.01. Additionally, in tumors that stained ≤80% for CD44, 4 of 10 (40%) achieved pCR, compared with 0 of 13 >80%, P = 0.02. In tumors that stained high for TFAP2C (≥80%) and low for CD44 (≤80%), 4 of 7 (57%) achieved pCR, compared with 0 of 16 in all other groups (P = 0.004).
CONCLUSIONS: TFAP2C repressed CD44 expression in basal-derived breast cancer. In primary breast cancer specimens, high TFAP2C and low CD44 expression were associated with pCR after neoadjuvant chemotherapy and could be predictive of tumors that have improved response to neoadjuvant chemotherapy.

Shiu KK, Wetterskog D, Mackay A, et al.
Integrative molecular and functional profiling of ERBB2-amplified breast cancers identifies new genetic dependencies.
Oncogene. 2014; 33(5):619-31 [PubMed] Related Publications
Overexpression of the receptor tyrosine kinase ERBB2 (also known as HER2) occurs in around 15% of breast cancers and is driven by amplification of the ERBB2 gene. ERBB2 amplification is a marker of poor prognosis, and although anti-ERBB2-targeted therapies have shown significant clinical benefit, de novo and acquired resistance remains an important problem. Genomic profiling has demonstrated that ERBB2+ve breast cancers are distinguished from ER+ve and 'triple-negative' breast cancers by harbouring not only the ERBB2 amplification on 17q12, but also a number of co-amplified genes on 17q12 and amplification events on other chromosomes. Some of these genes may have important roles in influencing clinical outcome, and could represent genetic dependencies in ERBB2+ve cancers and therefore potential therapeutic targets. Here, we describe an integrated genomic, gene expression and functional analysis to determine whether the genes present within amplicons are critical for the survival of ERBB2+ve breast tumour cells. We show that only a fraction of the ERBB2-amplified breast tumour lines are truly addicted to the ERBB2 oncogene at the mRNA level and display a heterogeneous set of additional genetic dependencies. These include an addiction to the transcription factor gene TFAP2C when it is amplified and overexpressed, suggesting that TFAP2C represents a genetic dependency in some ERBB2+ve breast cancer cells.

Kulak MV, Cyr AR, Woodfield GW, et al.
Transcriptional regulation of the GPX1 gene by TFAP2C and aberrant CpG methylation in human breast cancer.
Oncogene. 2013; 32(34):4043-51 [PubMed] Free Access to Full Article Related Publications
The complexity of gene regulation has created obstacles to defining mechanisms that establish the patterns of gene expression characteristic of the different clinical phenotypes of breast cancer. TFAP2C is a transcription factor that has a critical role in the regulation of both estrogen receptor-alpha (ERα) and c-ErbB2/HER2 (Her2). Herein, we performed chromatin immunoprecipitation and direct sequencing (ChIP-seq) for TFAP2C in four breast cancer cell lines. Comparing the genomic binding sites for TFAP2C, we identified that glutathione peroxidase (GPX1) is regulated by TFAP2C through an AP-2 regulatory region in the promoter of the GPX1 gene. Knockdown of TFAP2C, but not the related factor TFAP2A, resulted in an abrogation of GPX1 expression. Selenium-dependent GPX activity correlated with endogenous GPX1 expression and overexpression of exogenous GPX1 induced GPX activity and significantly increased resistance to tert-butyl hydroperoxide. Methylation of the CpG island encompassing the AP-2 regulatory region was identified in cell lines where TFAP2C failed to bind the GPX1 promoter and GPX1 expression was unresponsive to TFAP2C. Furthermore, in cell lines where GPX1 promoter methylation was associated with gene silencing, treatment with 5'-aza-2-deoxycytidine (5'-aza-dC) (an inhibitor of DNA methylation) allowed TFAP2C to bind to the GPX1 promoter resulting in the activation of GPX1 RNA and protein expression. Methylation of the GPX1 promoter was identified in ∼20% of primary breast cancers and a highly significant correlation between the TFAP2C and GPX1 expression was confirmed when considering only those tumors with an unmethylated promoter, whereas the related factor, TFAP2A, failed to demonstrate a correlation. The results demonstrate that TFAP2C regulates the expression of GPX1, which influences the redox state and sensitivity to oxidative stress induced by peroxides. Given the established role of GPX1 in breast cancer, the results provide an important mechanism for TFAP2C to further influence oncogenesis and progression of breast carcinoma cells.

Elmegeed GA, Khalil WK, Mohareb RM, et al.
Cytotoxicity and gene expression profiles of novel synthesized steroid derivatives as chemotherapeutic anti-breast cancer agents.
Bioorg Med Chem. 2011; 19(22):6860-72 [PubMed] Related Publications
Anti-cancer agents which combine two biologically active compounds in one such as steroidal heterocyclic derivatives attain both hormone and cytotoxic effects on cancer cells. The aim of the present study is to synthesize and evaluate new potential chemotherapeutic anti-breast cancer agents. Several pyridazino-, pyrimido-, quinazolo-, oxirano- and thiazolo-steroid derivatives were synthesized. The structure of the novel steroid derivatives was confirmed using the analytical and spectral data. The most structurally promising of the novel synthesized steroid derivatives, compounds 8, 12, 17, 20, 22c, 24c, 30a and 30b, were investigated individually as anti-breast cancer agents against human breast cancer cells (MCF-7) using sulforhodamine B (SRB) assay. The tested compounds 17, 20, 22c and 8 showed potent broad spectrum cytotoxic activity in vitro after 48 h incubation. Compound 17 (IC(50)=2.5 μM) exhibited more inhibitory influence on MCF-7 growth than the reference drug doxorubicin (Dox) (IC(50)=4.5 μM) after 48 h incubation. Also, the present study showed that all the tested steroid derivatives exhibited significant depletion with various intensities in gene expression of breast cancer related genes (VEGF, CYP19 and hAP-2γ). Noteworthy, compounds 17, 20 and 22c showed the most pronounced effect in this respect.

Nettersheim D, Gillis A, Biermann K, et al.
The seminoma cell line TCam-2 is sensitive to HDAC inhibitor depsipeptide but tolerates various other chemotherapeutic drugs and loss of NANOG expression.
Genes Chromosomes Cancer. 2011; 50(12):1033-42 [PubMed] Related Publications
Seminomas and embryonal carcinomas (EC) are both type II germ cell tumor (GCT) entities and develop from the same precursor lesion (carcinoma-in situ, CIS). However, they show significant differences in growth behavior, differentiation potential, and gene expression. Although ECs are prone to differentiate into all three germ layers and give rise to the non-seminomatous GCT entities teratoma, choriocarcinoma, and yolk-sac tumor, differentiation of seminomas to these entities is only rarely observed. This might reflect the ability of seminomas to actively inhibit differentiation processes evoked by environmental cues. Also, it is not known why CIS gives rise to seminoma in some patients and to non-seminoma in the others. Here, we treated the seminoma-like cell line TCam-2 with the HDAC-inhibitor Depsipeptide, the global demethylating agent 5-aza-2'-deocycytidine, all-trans retinoic acid and the monaminooxidase inhibitor Tranylcipromine and also used knock down approaches to reduce expression of the pluripotency marker NANOG and/or the inhibitor of primordial germ cell differentiation TFAP2C. We found that TCam-2 cells induce apoptosis when treated with Depsipeptide (> 10 nM) but are resistant to treatments with 5-aza-2'-deocycytidine, all-trans retinoic acid and Tranylcipromine, highlighting Depsi as a treatment option for seminomas. We show that TCam-2 cells up-regulate endoderm- and throphectoderm-associated genes after down-regulation of NANOG expression; however, morphologically no indications of differentiation could be found. Instead, we observed up-regulation of OCT3/4 and SOX17 in TCam-2-NANOG knockdown and speculate that this compensates for the loss of the NANOG protein. Hence, NANOG is not a primary target gene responsible for the inhibition of differentiation in seminomas.

Stine ZE, McGaughey DM, Bessling SL, et al.
Steroid hormone modulation of RET through two estrogen responsive enhancers in breast cancer.
Hum Mol Genet. 2011; 20(19):3746-56 [PubMed] Free Access to Full Article Related Publications
RET, a gene causatively mutated in Hirschsprung disease and cancer, has recently been implicated in breast cancer estrogen (E2) independence and tamoxifen resistance. RET displays both E2 and retinoic acid (RA)-dependent transcriptional modulation in E2-responsive breast cancers. However, the regulatory elements through which the steroid hormone transcriptional regulation of RET is mediated are poorly defined. Recent genome-wide chromatin immunoprecipitation-based studies have identified 10 putative E2 receptor-alpha (ESR1) and RA receptor alpha-binding sites at the RET locus, of which we demonstrate only two (RET -49.8 and RET +32.8) display significant E2 regulatory response when assayed independently in MCF-7 breast cancer cells. We demonstrate that endogenous RET expression and RET -49.8 regulatory activity are cooperatively regulated by E2 and RA in breast cancer cells. We identify key sequences that are required for RET -49.8 and RET +32.8 E2 responsiveness, including motifs known to be bound by ESR1, FOXA1 and TFAP2C. We also report that both RET -49.8 regulatory activity and endogenous RET expression are completely dependent on ESR1 for their (E2)-induction and that ESR1 is sufficient to mediate the E2-induced enhancer activity of RET -49.8 and RET +32.8. Finally, using zebrafish transgenesis, we also demonstrate that RET -49.8 directs reporter expression in the central nervous system and peripheral nervous system consistent with the endogenous ret expression. Taken collectively, these data suggest that RET transcription in breast cancer cells is modulated by E2 via ESR1 acting on multiple elements collectively.

Bell A, Bell D, Weber RS, El-Naggar AK
CpG island methylation profiling in human salivary gland adenoid cystic carcinoma.
Cancer. 2011; 117(13):2898-909 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: DNA methylation is a fundamental epigenetic event associated with physiologic and pathologic conditions, including cancer. Hypermethylation of CpG islands at active gene promoters leads to transcriptional repression, whereas hypomethylation is associated with gene overexpression. The aim of this study was to identify genes in adenoid cystic carcinoma (ACC) of salivary gland strongly deregulated by epigenetic CpG island methylation, to validate selected genes by conventional techniques, and to correlate the findings with clinicopathologic factors.
METHODS: The authors analyzed 16 matched normal and tumor tissues for aberrant DNA methylation using the methylated CpG island amplification and microarray method and the pyrosequencing technique.
RESULTS: Microarray analysis showed hypomethylation in 7 and hypermethylation in 32 CpG islands. Hypomethylation was identified in CpG islands near FBXO17, PHKG1, LOXL1, DOCK1, and PARVG. Hypermethylation was identified near genes encoding predominantly transcription factors (EN1, FOXE1, GBX2, FOXL1, TBX4, MEIS1, LBX2, NR2F2, POU3F3, IRX3, TFAP2C, NKX2-4, PITX1, NKX2-5), and 13 genes with different functions (MT1H, EPHX3, AQPEP, BCL2L11, SLC35D3, S1PR5, PNLIPRP1, CLIC6, RASAL, XRN2, GSTM5, FNDC1, INSRR). Four CpG islands by EN1, FOXE1, TBX4, and PITX1 were validated by pyrosequencing.
CONCLUSIONS: The highly methylated genes in tumor versus normal tissue are linked to developmental, apoptotic, and other fundamental cellular pathways, suggesting that down-regulation of these genes is associated with ACC development and progression. With EN1 hypermethylation showing potential as a possible biomarker for ACC in salivary gland, the biological and therapeutic implications of these findings require further preclinical investigations.

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