GATA Transcription Factors and Cancer

The methylation of C/EBP β gene promoter and regulated by GATA-2 protein

Mammalian genomes are punctuated by DNA sequences containing an atypically high frequency of CpG sites (CpG islands; CGIs) that are associated with the majority of annotated gene promoters. Methylated C bases of CpG sites inhibit the expression of downstream genes. During the differentiation of 3T3-L1 preadipocytes, the CCAAT/enhancer-binding protein (C/EBP) β gene plays an important role. We studied the CpG island methylation status of the C/EBP β promoter and its relationship with the GATA-2 protein. We used computer analysis to determine that the C/EBP β promoter sequence is rich in CGIs, and observed that two of seven methylated C bases were demethylated during the preadipocyte differentiation using bisulfite sequencing PCR (BSP). This corresponded with the onset of notable C/EBP β gene expression. Immunofluorescence and molecular docking showed that the GATA-2 protein binds the C/EBP β promoter in front of the first demethylated CpG site. We also found that expression of GATA-2 and C/EBP β proteins is negatively correlated. These results indicate that the methylated C bases in the C/EBP β promoter relate to expression of the C/EBP β gene, and that its demethylation is linked with GATA-2 protein association.

p21-activated kinase-1 signaling regulates transcription of tissue factor and tissue factor pathway inhibitor

Tissue factor (TF) is a cell-surface glycoprotein responsible for initiating the coagulation cascade. Besides its role in homeostasis, studies have shown the implication of TF in embryonic development, cancer-related events, and inflammation via coagulation-dependent and -independent (signaling) mechanisms. Tissue factor pathway inhibitor (TFPI) plays an important role in regulating TF-initiated blood coagulation. Therefore, transcriptional regulation of TF expression and its physiological inhibitor TFPI would allow us to understand the critical step that controls many different processes. From a gene profiling study aimed at identifying differentially regulated genes between wild-type (WT) and p21-activated kinase 1-null (PAK1-KO) mouse embryonic fibroblasts (MEFs), we found TF and TFPI are differentially expressed in the PAK1-KO MEFs in comparison with wild-type MEFs. Based on these findings, we further investigated in this study the transcriptional regulation of TF and TFPI by PAK1, a serine/threonine kinase. We found that the PAK1·c-Jun complex stimulates the transcription of TF and consequently its procoagulant activity. Moreover, PAK1 negatively regulates the expression of TFPI and additionally contributes to increased TF activity. For the first time, this study implicates PAK1 in coagulation processes, through its dual transcriptional regulation of TF and its inhibitor.

Promoter hypermethylation in male breast cancer: analysis by multiplex ligation-dependent probe amplification

Introduction

Epigenetic events are, along with genetic alteration, important in the development and progression of cancer. Promoter hypermethylation causes gene silencing and is thought to be an early event in carcinogenesis. The role of promoter hypermethylation in male breast cancer has not yet been studied.

Methods

In a group of 108 male breast cancers, the methylation status of 25 genes was studied using methylation-specific multiplex ligation-dependent probe amplification. Methylation of more than 15% was regarded indicative for promoter hypermethylation. Methylation status was correlated with clinicopathological features, with patients' outcome and with 28 female breast cancer cases.

Results

Promoter hypermethylation of the genes MSH6, WT1, PAX5, CDH13, GATA5 and PAX6 was seen in more than 50% of the cases, but was uncommon or absent in normal male breast tissue. High overall methylation status was correlated with high grade (P = 0.003) and was an independent predictor of poor survival (P = 0.048; hazard ratio 2.5). ESR1 and GSTP1 hypermethylation were associated with high mitotic count (P = 0.037 and P = 0.002, respectively) and high grade (both P = 0.001). No correlation with survival was seen for individual genes. Compared with female breast cancers (logistic regression), promoter hypermethylation was less common in a variety of genes, particularly ESR1 (P = 0.005), BRCA1 (P = 0.010) and BRCA2 (P < 0.001). The most frequently hypermethylated genes (MSH6, CDH13, PAX5, PAX6 and WT1) were similar for male and female breast cancer.

Conclusion

Promoter hypermethylation is common in male breast cancer and high methylation status correlates with aggressive phenotype and poor survival. ESR1 and GSTP1 promoter hypermethylation seem to be involved in development and/or progression of high-grade male breast cancer. Although female and male breast cancer share a set of commonly methylated genes, many of the studied genes are less frequently methylated in male breast cancer, pointing towards possible differences between male and female breast carcinogenesis.

Immunohistochemical evaluation of GATA3 expression in tumors and normal tissues: a useful immunomarker for breast and urothelial carcinomas

GATA3 expression has been reported in urothelial and breast carcinomas; however, the published data on GATA3 expression in tumors from other organs are limited. Immunohistochemical evaluation of GATA3 expression in 1,110 carcinomas and 310 cases of normal tissue using tissue microarray sections, 48 breast and bladder biopsy specimens, and 53 breast fine-needle aspiration biopsy specimens was performed. Sixty-two of 72 urothelial carcinomas (86%) and 138 of 147 breast carcinomas (94%) tested positive for GATA3. All other cases, except for 2 of 96 endometrial carcinomas, tested negative for GATA3. On fine-needle aspiration biopsy samples, 88% of primary breast carcinomas and 82% of metastatic breast carcinomas tested positive for GATA3. Our study revealed that GATA3 is a sensitive and specific marker for the diagnosis of breast and urothelial carcinomas. When working on a tumor of unknown origin, GATA3 should be routinely included in the initial screening panel if either a breast or urothelial primary tumor is suspected.

Using mice to unveil the genetics of cancer resistance

In the UK, four in ten people will develop some form of cancer during their lifetime, with an individual's relative risk depending on many factors, including age, lifestyle and genetic make-up. Much research has gone into identifying the genes that are mutated in tumorigenesis with the overwhelming majority of genetically-modified (GM) mice in cancer research showing accelerated tumorigenesis or recapitulating key aspects of the tumorigenic process. Yet if six out of ten people will not develop some form of cancer during their lifetime, together with the fact that some cancer patients experience spontaneous regression/remission, it suggests there are ways of 'resisting' cancer. Indeed, there are wildtype, spontaneously-arising mutants and GM mice that show some form of 'resistance' to cancer. Identification of mice with increased resistance to cancer is a novel aspect of cancer research that is important in terms of providing both chemopreventative and therapeutic options. In this review we describe the different mouse lines that display a 'cancer resistance' phenotype and discuss the molecular basis of their resistance.

EZH2 genetic variants affect risk of gastric cancer in the Chinese Han population

Enhancer of zeste 2 (EZH2) gene encodes a histone methyltransferase that constitutes the catalytic component of the polycomb repressive complex-2 (PRC2) to initiate epigenetic silencing of genes. It is reported that the expression level of EZH2 in gastric cancer tissue was highly correlated with tumor progression, however, whether EZH2 genetic variants were associated with the risk of gastric cancer remains yet unknown. In this study, we conducted a genotyping analysis for EZH2 in 311 cases of gastric cancer and 425 controls from the Chinese Han population. We found five single nucleotide polymorphisms (SNP; rs12670401, rs6464926, rs2072407, rs734005, and rs734004) of EZH2 gene were significantly associated with the risk of gastric cancer. Of which, the rs12670401 with the minor allele C and rs6464926 with the minor allele T revealed strong associations with increased gastric cancer risk [P = 0.009, adjusted odds ratio (aOR) = 1.327, 95% CI = 1.075-1.683 and P = 0.012, aOR = 1.310, 95% CI = 1.059-1.619]. The other three SNPs, rs2072407, rs734005, and rs734004 contributed to significantly reduced risk of gastric cancer (P = 0.033, aOR = 0.787, 95% CI = 0.633-0.981, P = 0.045, aOR = 0.799, 95% CI = 0.642-0.995 and P = 0.048, aOR = 0.803, 95% CI = 0.645-0.999), respectively. We further found that rs12670401 and rs6464926 were in a strong LD while rs2072407, rs734005, and rs734004 were in another. Haplotype analysis of the five SNPs showed that haplotype CCTCT reduced the risk of gastric cancer (P = 0.031 and aOR = 0.784), while haplotype GTCTC significantly elevated the risk of gastric cancer (P = 0.011 and aOR = 1.310). We concluded that EZH2 variants were significantly associated with gastric cancer risk. Our results for the first time provided new insight into susceptibility factors of EZH2 gene variants in carcinogenesis of gastric cancer of the Chinese Han population.