摘要： Calcineurin inhibitors such as cyclosporin A (CsA) are the mainstay of immunosuppressive treatment for organ transplant recipients. Squamous cell carcinoma (SCC) of the skin is a major complication of treatment with these drugs, with a 65 to 100-fold higher risk than in the normal population(1). By contrast, the incidence of basal cell carcinoma (BCC), the other major keratinocyte-derived tumour of the skin, of melanoma and of internal malignancies increases to a significantly lesser extent(1). Here we report that genetic and pharmacological suppression of calcineurin/nuclear factor of activated T cells (NFAT) function promotes tumour formation in mouse skin and in xenografts, in immune compromised mice, of H-ras(V12) (also known as Hras1)-expressing primary human keratinocytes or keratinocyte-derived SCC cells. Calcineurin/NFAT inhibition counteracts p53 (also known as TRP53)-dependent cancer cell senescence, thereby increasing tumorigenic potential. ATF3, a member of the 'enlarged' AP-1 family, is selectively induced by calcineurin/NFAT inhibition, both under experimental conditions and in clinically occurring tumours, and increased ATF3 expression accounts for suppression of p53-dependent senescence and enhanced tumorigenic potential. Thus, intact calcineurin/NFAT signalling is critically required for p53 and senescence-associated mechanisms that protect against skin squamous cancer development.

摘要： Context: Hypospadias is a common congenital malformation of the male external genitalia with a multifactorial etiology. Little is known about the genes involved in hypospadias. A few genetic associations have been reported but mainly in studies of small sample size. Most of these associations have not been replicated. Objective: The aim of this study was to investigate whether previously reported associations for four single-nucleotide polymorphisms (SNPs) in genes involved in hormonal pathways could be replicated in a large Dutch hypospadias sample. The SNPs investigated are rs523349 in steroid 5 alpha-reductase (SRD5A2), rs6932902 in estrogen receptor 1 (ESR1), rs2987983 in ESR2, and rs11119982 in activating transcription factor 3 (ATF3). Design, Participants, and Methods: We genotyped 620 Caucasian hypospadias cases and 596 controls for these SNPs using TaqMan-based genotyping. Results: We did not replicate the associations of the SNPs in SRD5A2 and ESR1 with hypospadias. The SNPs in ESR2 and ATF3 were borderline associated with hypospadias [odds ratios 0.9 (95% confidence interval 0.7-1.0) and 1.2 (95% confidence interval 1.0-1.4), respectively] but in the opposite direction compared with earlier publications. Stratification according to localization of the urethral opening produced comparable results in the subgroups. Conclusions: The lack of consistency between our and previously performed studies might represent spurious results or chance findings in our or the earlier studies, differences in criteria used to select the study populations, or a real difference between populations, i.e. different genes contributing to disease risk. These results once again confirm the importance of replication in genetic association approaches. (J Clin Endocrinol Metab 95: 2384-2390, 2010)

关键词： AdipoR2   ATF3   ER stress   insulin resistance   obesity  

摘要： Adiponectin acts as an insulin-sensitizing adipokine that protects against obesity-linked metabolic disease, which is generally associated with endoplasmic reticulum (ER) stress. The physiological effects of adiponectin on energy metabolism in the liver are mediated by its receptors. We found that the hepatic expression of adiponectin receptor 2 (AdipoR2) was lower, but the expression of markers of the ER stress pathway, 78 kDa glucose-regulated protein (GRP78) and activating transcription factor 3 (ATF3), was higher in the liver of ob/ob mice compared with control mice. To investigate the regulation of AdipoR2 by ER stress, we added thapsigargin, an ER stress inducer, to a human hepatocyte cell line, HepG2. Addition of the ER stress inducer increased the levels of GRP78 and ATF3, and decreased that of AdipoR2, whereas addition of a chemical chaperone, 4-phenyl butyric acid (PBA), could reverse them. Up- or down-regulation of ATF3 modulated the AdipoR2 protein levels and AdipoR2 promoter activities. Reporter gene assays using a series of 5'-deleted AdipoR2 promoter constructs revealed the location of the repressor element responding to ER stress and ATF3. In addition, using electrophoretic mobility shift and chromatin immunoprecipitation assays, we identified a region between nucleotides -94 and -86 of the AdipoR2 promoter that functions as a putative ATF3-binding site in vitro and in vivo. Thus, our findings suggest that the ER stress-induced decrease in both protein and RNA of AdipoR2 results from a concomitant increase in expression of ATF3, which may play a role in the development of obesity-induced insulin resistance and related ER stress in hepatocytes.

关键词： Apoptosis   p53   Protein Degradation   Tumor Suppressor   Ubiquitination   ATF3   E6   E6AP   HPV   Cervical Cancer  

摘要： Genomic integration of human papillomavirus (HPV) DNA accounts for more than 90% of cervical cancers. High-risk genital HPVs encode E6 proteins that can interact with a cellular ubiquitin ligase E6-associated protein (E6AP) and target the tumor suppressor p53 for ubiquitin-mediated proteolysis. Currently, how this critical event is regulated is largely unknown. Here we report that activating transcription factor 3 (ATF3), a broad DNA damage sensor whose expression is frequently downregulated in cervical cancer, interacted with E6 and prevented p53 from ubiquitination and degradation mediated by the viral protein. Consistent with its role as a potent E6 antagonist, ATF3 expressed enforcedly in HPV-positive SiHa cells activated p53, leading to expression of p53-target genes (e. g. p21 and PUMA), cell cycle arrest and apoptotic cell death. The leucine zipper domain of ATF3 appears indispensable for these effects as an ATF3 mutant lacking this domain failed to interact with E6 and activate p53 in the cervical cancer cells. The prevention of p53 degradation was unlikely caused by binding of ATF3 to the tumor suppressor, but rather was a consequence of disruption of the E6-E6AP interaction by ATF3. These results indicate that ATF3 plays a key role in a mechanism defending against HPV-induced carcinogenesis, and could serve as a novel therapeutic target for HPV-positive cancers.

摘要： Purpose Hypospadias is a common congenital malformation of the male external genitalia with a multifactorial etiology. Little is known about the genes involved in Hypospadias. A few genetic associations have been reported, but mainly in studies of small sample size. Most of these associations have not been replicated. The aim of this study was to investigate whether previously reported associations for four single nucleotide polymorphisms (SNPs) in genes involved in hormonal pathways could be replicated in a large Dutch Hypospadias sample. The SNPs investigated are rs523349 in steroid-5-alpha-reductase (SRD5A2), rs6932902 in estrogen receptor 1 (ESR1), rs2987983 in ESR2 and rs11119982 in activating transcription factor 3 (ATF3). Material and Methods We genotyped 620 Caucasian Hypospadias cases and 596 controls for the four SNPs using TaqMan-based genotyping. Results We did not replicate the associations of the SNPs in SRD5A2 and ESR1 with Hypospadias. The SNPs in ESR2 and ATF3 were borderline associated with Hypospadias (odds ratios 0.9 (95% confidence interval (CI) 0.7-1.0) and 1.2 (95% CI 1.0-1.4), respectively), but in the opposite direction compared to earlier publications. Stratification according to the localization of the urethral opening produced comparable results in the subgroups. Conclusions The lack of consistency between our and previously performed studies might represent spurious results or chance findings found in our or the earlier studies, differences in criteria used to select the study populations, or a real difference between the populations. These results once again confirm the importance of replication in genetic association approaches.

摘要： Capsaicin, a natural product of the Capsicum species of red peppers, is known to induce apoptosis and suppress growth. Non-steroidal anti-inflammatory drug-activated gene-1 (NAG-1) is a cytokine associated with pro-apoptotic and antitumorigenic property in colorectal and lung cancer. Our data demonstrate that capsaicin leads to induction of apoptosis and up-regulates NAG-1 gene expression at the transcriptional level. Overexpression of CCAAT/enhancer binding protein beta (C/EBP beta) caused a significant increase of basal and capsaicin-induced NAG-1 promoter activity. We subsequently identified C/EBP beta binding sites in the NAG-1 promoter responsible for capsaicin-induced NAG-1 transactivation. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay confirmed binding of C/EBP beta to the NAG-1 promoter. Capsaicin treatment resulted in an increase of phosphorylated serine/threonine residues on C/EBP beta, and the immunoprecipitation study showed that capsaicin enhanced binding of C/EBP beta with glycogen synthase kinase 3 beta (GSK3 beta) and activating transcription factor 3 (ATF3). The phosphorylation and interaction of C/EBP beta with GSK3 beta and ATF3 are decreased by the inhibition of the GSK3 beta and Protein Kinase C pathways. Knockdown of C/EBP beta, GSK3 beta or ATF3 ameliorates NAG-1 expression induced by capsaicin treatment. These data indicate that C/EBP beta phosphorylation through GSK3 beta may mediate capsaicin-induced expression of NAG-1 and apoptosis through cooperation with ATF3 in human colorectal cancer cells.