Is HCMV a tumor promoter?

Human cytomegalovirus (HCMV) is a beta-herpesvirus that causes persistent infection in humans and can cause severe disease in fetuses and immunocompromised individuals. Although HCMV is not currently causally implicated in human cancer, emerging evidence suggests that HCMV infection and expression may be specifically associated with human malignancies including malignant glioma, colon, and prostate cancer. In addition, multiple investigators have demonstrated that HCMV can dysregulate signaling pathways involved in initiation and promotion of malignancy, including tumor suppressor, mitogenic signaling, inflammatory, immune regulation, angiogenesis and invasion, and epigenetic mechanisms. This review highlights some of the recent evidence that HCMV might play a role in modulating the tumor microenvironment as well as in the initiation and promotion of tumor cells themselves.     

SIRT1: Tumor promoter or tumor suppressor?

Over the past decade, an intensive research on the basic biology of aging has identified individual genes either directly or indirectly involved in regulating the aging process in various model organisms. This allows us to garner all the information available from studies of model organisms and to apply them to better understand aging and cancer in human. Among many genes thus far reported contributing to aging process, the yeast silent information regulator-2 (SIR2) and its homologues in other species, which belong to the family of type III histone and protein deacetylases, have been the subject of active discussion. The demonstrated roles of SIRT1, the mammalian counterpart of the yeast SIR2, reveal that SIRT1 regulates important cellular processes including anti-apoptosis, neuronal protection, cellular senescence, aging and longevity. Based on the observations that SIRT1 is upregulated in tumor cells, the hypothesis is that deregulation of SIRT1 expression may promote tumorigenesis by altering cellular signaling or by inducing modulation of chromatin remodeling leading to promotion of tumorigenesis. Further studies will shed new light on the underlying mechanisms of tumorigenesis mediated by SIRT1.     

Is there a future for TNF promoter polymorphisms?

The in vitro study of TNF promoter polymorphism (SNP) function was stimulated by the numerous case-control (association) studies of the polymorphisms in relation to human disease and the appearance of several studies claiming to show a functional role for these SNPs provided a further impetus to researchers interested in the role of TNF in their disease of interest. In this review we consider case-control studies, concentrating on the autoimmune and inflammatory diseases rheumatoid arthritis, multiple sclerosis, ankylosing spondylitis, and asthma, and on infectious diseases including malaria, hepatitis B and C infection, leprosy and sepsis/septic shock. We also review the available evidence on the functional role of the various TNF promoter polymorphisms. In general, case-control studies have produced mixed results, with little consensus in most cases on whether any TNF polymorphisms are actually associated with disease, although results have been more consistent in the case of infectious diseases, particularly malaria. Functional studies have also produced mixed results but recent work suggests that the much studied -308G/A polymorphism is not functional, while the function of other TNF polymorphisms remains controversial. Studies of the TNF region are increasingly using extended haplotypes that can better capture the variation of the MHC region.     

Activation of the skeletal α-actin promoter during muscle regeneration

Little is known conerning promoter regulation of genes in regenerating skeletal muscles. In young rats, recovery of muscle mass and protein content is complete within 21 days. During the initial 5–10 days of regeneration, mRNA abundance for IGF-I, myogenin and MyoD have been shown to be dramatically increased. The skeletal -actin promoter contains E box and serum response element (SRE) regulatory regions which are directly or indirectly activated by myogenin (or MyoD) and IGF-I proteins, respectively. We hypothesized that the skeletal -actin promoter activity would increase during muscle regeneration, and that this induction would occur before muscle protein content returned to normal. Total protein content and the percentage content of skeletal -actin protein was diminished at 4 and 8 days and re-accumulation had largely occurred by 16 days post-bupivacaine injection. Skeletal - actin mRNA per whole muscle was decreased at day 8, and thereafter returned to control values. During regeneration at day 8, luciferase activity (a reporter of promoter activity) directed by –424 skeletal -actin and –99 skeletal -actin promoter constructs was increased by 700% and 250% respectively; however, at day 16, skeletal -actin promoter activities were similar to control values. Thus, initial activation of the skeletal - actin promoter is associated with regeneration of skeletal muscle, despite not being sustained during the later stages of regrowth. The proximal SRE of the skeletal -actin promoter was not sufficient to confer a regeneration-induced promoter activation, despite increased serum response factor protein binding to this regulatory element in electrophoretic mobility shift assays. Skeletal -actin promoter induction during regeneration is due to a combination of regulatory elements, at least including the SRE and E box. © Kluwer Academic Publishers.     

Interleukin-18 promoter polymorphisms in patients with Behçet's disease

Beh?et's disease (BD) is an idiopathic systemic inflammatory disease and is considered to be a T helper 1 (Th1) type cytokine driven disorder. Moreover, levels of interleukin-18 (IL-18), a pivotal mediator of Th1 cytokine response, have been reported to be upregulated in BD. Therefore, we investigated the distribution of IL-18 promoter -607 C/A and -137 G/C polymorphisms in 103 BD patients (mean age 41.0 years; 48 male, 55 female) using allele-specific-polymerase chain reaction. As compared with healthy control subjects, BD patients had a significantly higher frequency of the -607 CC genotype (42.7% vs 23.3%, odds ratio [OR] = 2.455, 95% confidence interval [CI] = 1.350-4.461, p(c) = 0.021) and a higher frequency of the -607 C allele (60.7% vs 48.1%, OR = 1.668, 95% CI = 1.129-2.464, p = 0.0101). Haplotype analysis showed that BD patients had significantly less -607A/-137G haplotype (27.3% vs 44.2%, OR = 0.469, 95% CI = 0.268-0.820, p(c) = 0.032) and -607A/-137G haplotype homozygote (5.8% vs 20.4%, OR = 0.242, 95% CI = 0.096-0.612, p(c) = 0.014) than control subjects. In addition, the frequency of -607C/-137G haplotype homozygote was significantly higher in BD patients than control subjects (48.5% vs 20.4%, OR = 3.684, 95% CI = 1.997-6.791, p(c) = 0.0014). Although there were no associations between the polymorphisms and clinical manifestations or severity, patients with the -607 CC genotype or -607C/-137G haplotype homozygote showed significantly earlier symptom development (p = 0.034 by ANOVA; p = 0.009 by t-test, respectively) than those with other genotypes or diplotypes. These results suggest that the IL-18 promoter gene is a candidate susceptibility gene in BD patients.     

Telomerase promoter mutations in cancer: an emerging molecular biomarker?

Cell immortalization has been considered for a long time as a classic hallmark of cancer cells. Besides telomerase reactivation, such immortalization could be due to telomere maintenance through the “alternative mechanism of telomere lengthening” (ALT) but the mechanisms underlying both forms of reactivation remained elusive. Mutations in the coding region of telomerase gene are very rare in the cancer setting, despite being associated with some degenerative diseases. Recently, mutations in telomerase (TERT) gene promoter were found in sporadic and familial melanoma and subsequently in several cancer models, notably in gliomas, thyroid cancer and bladder cancer. The importance of these findings has been reinforced by the association of TERT mutations in some cancer types with tumour aggressiveness and patient survival. In the first part of this review, we summarize the data on the biology of telomeres and telomerase, available methodological approaches and non-neoplastic diseases associated with telomere dysfunction. In the second part, we review the information on telomerase expression and genetic alterations in the most relevant types of cancer (skin, thyroid, bladder and central nervous system) on record, and discuss the value of telomerase as a new biomarker with impact on the prognosis and survival of the patients and as a putative therapeutic target.     

pGL3-Claudin-1 promoter荧光素酶报告基因质粒的构建及其功能鉴定

背景：Claudin-1是一种多功能蛋白,除了组成紧密连接封闭细胞间隙,它在转录水平的表达失调可能作为一种分子标志反映到恶性肿瘤的侵袭转移和预后中。 目的：构建重组大鼠重组Claudin-1萤光素酶报告基因质粒。 方法：设计和合成包含5’非转录区的约2 000 bp的脱氧核糖核酸链,经过限制性内切酶KpnⅠ和MluⅠ酶切后插入到pGL3-Basic载体中,并用感受态E.coli DH5α和Pmd18-T-simple载体筛选阳性样品。阳性克隆通过测序和PCR证实。实验分为4组：对照组,阳性对照组(pGL3-promoter质粒转染),阴性对照组(转染pGL3-Basic质粒),实验组(转染pGL3-Claudin-1 promoter质粒)。将质粒转染293T细胞检测Claudin-1启动子活性。 结果与结论：重组质粒DNA测序结果采用NCBI blast比对与GenBank(gi|62750811)中大鼠Claudin-1基因启动子序列完全匹配。重组萤光素酶报告基因转录活性检测与pGL3-Basic质粒相比,重组pGL3质粒转录活性明显增强 (P < 0.001)。经过测序和转染结果证实有效的pGL3-Claudin-1启动子质粒构建成功。     

Epigenetic mechanisms regulate ΔNP73 promoter function in human tonsil B cells

ΔNp73 is an anti-apoptotic product of the TP73 gene whose function in the immune system has not been extensively studied. We analyzed human tonsil B cell subpopulations physically subdivided into resting or activated fractions and found ΔNp73 gene expression essentially in cells bearing features of activation. Moreover, and accordingly, both these fractions proved to be sensitive to treatment in culture with the polyclonal activator TPA that caused substantial increase in ΔNp73 mRNA and protein expression.We also analyzed the TP73 oncogenic-relevant internal promoter 2 (P2) and identified epigenetics as its major regulatory factor since active DNA and histone configurations strictly correlated with ΔNp73 expression upon activation by agents capable of loosening chromatin compaction.Finally, in line with the known TPA pathway, we found that nuclear proteins could bind a sequence corresponding to a unique AP1 site on promoter 2 selectively in the activated cell fraction.Our results suggest a ΔNp73 function in B cell immunity, indicate epigenetics as master TP73 P2 regulator, and point to AP1 site occupancy as playing an putative mechanistic role in this process.     

Characterization of Kaposi’s sarcoma-associated herpesvirus/human herpesvirus-8 ORF57 promoter

Summary.  Kaposi’s sarcoma-associated herpesvirus (KSHV) is a recently discovered human gamma herpesvirus (HHV-8) that plays an important role in Kaposi’s sarcoma development. Here, we further characterize the regulation of the early HHV-8 gene, open reading frame 57 (ORF57). ORF57 is a spliced gene consisting of two exons with a 108-bp intron near the 5′ end. The ORF57 mRNA can potentially be initiated at two different start sites, and its expression can be significantly stimulated by ORF50, an HHV-8 immediate early gene. The target site for ORF50 transactivation was mapped to a 40-bp fragment compassing nt 81904 to 81943 in the ORF57 promoter. Our study on the regulation of ORF57 expression by ORF50 provides the basis for further studies on the regulation of HHV-8 lytic gene expression. Received October 28, 1999 Accepted June 22, 2000     

IL-6 promoter polymorphism (?174G/C) and systemic lupus erythematosus

We investigated the possible association between susceptibility to systemic lupus erythematosus (SLE) and single-nucleotide polymorphisms located in the promoter region of the interleukin-6 gene (?174 G/C) in a sample of the Egyptian population and the contribution of this polymorphism in the clinical or immunological manifestation of the disease. Forty-two Egyptian patients with SLE and 40 unrelated healthy control volunteers were genotyped by polymerase chain reaction followed by visualization on 4% agarose gel electrophoresis on ultraviolet transilluminator to detect the genotype distribution and allelic frequencies of the polymorphisms. The homozygous GG genotypes was significantly increased in SLE patients compared to control group (p value?=?0.04). On the other hand, the heterozygous G/C genotype was significantly elevated in the controls compared to SLE patients (p value?=?0.01). The odds ratio value for G/G was 2.6 with a 95% CI from 1.1 to 6.7. As regard the association of clinical manifestations to the genotype frequency, we found a statistical significant increase in the frequency of GG genotype with chest disease, nephritis, and arthritis. From this study, we suggest that G carrier is more susceptible to develop SLE and that SNP may have a role in the pathogenesis of the disease and may be associated with some of its clinical manifestations.     

Human cathepsin S gene (CTSS) promoter −25G/A polymorphism

We found a novel G → A change at nucleotide −25 within the promoter of the CTSS gene encoding the elastase cathepsin S. The CTSS−25G/A polymorphism could be detected by digestion with endonuclease BfmI. The frequency of the CTSS−25A allele was 0.457 in Caucasians and 0.431 in Canadian Inuit. Because of the importance of the CTSS gene product in vascular matrix remodeling, this polymorphism may be useful in the study of associations with atherosclerosis and related phenotypes. Received: October 12, 1999/Accepted: October 18, 1999     

Fatty acid desaturase 2 promoter mutation is not responsible for Δ6-desaturase deficiency

Dietary essential polyunsaturated fatty acids (PUFAs) require fatty acid desaturases (FADS) for conversion to long-chain PUFAs (LCPUFAs), which are critical for many aspects of human health. A Δ6-desaturase deficiency in a single patient was attributed to an insertion mutation in the FADS2 promoter. Later population studies have shown this thymidine nucleotide (T) insertion to be a common polymorphism (rs3834458). We examined correlations between rs3834458 variants and fatty acid evidence of FADS2 activity in a cohort of rheumatoid arthritis patients selected for low or nil consumption of n-3 LCPUFA as fish or fish oil. The presence of the T allele was associated with higher FADS2 activity, as indicated by higher conversion of plasma n-3 PUFA to LCPUFA. However, the T-insertion/deletion polymorphism did not affect FADS2 promoter activity in luciferase reporter assays in HepG2 or NIH/3T3 cells. Our results indicate that the polymorphism rs3834458 does not appear to directly affect FADS2 promoter activity and is not responsible for a previously reported Δ6-desaturase deficiency.     

The complex interaction between APOE promoter and AD: an Italian case�Ccontrol study

The single nucleotide polymorphisms (SNPs) rs449647, rs769446 and rs405509 in the promoter region of the APOE gene have been variously suggested to be ɛ4-independent risk factors for Alzheimer''s disease (AD). A previous Italian study found that the rs449647 was significantly associated with late-onset AD. The aim of this study was to verify whether these APOE promoter SNPs are genetic risk factors for AD and to investigate their interaction with the common APOE polymorphism. A total of 169 clinically diagnosed AD patients and 99 cognitively intact age-matched controls were included in the study. Significant associations with AD independent from sex, age and APOE/ɛ4 status were found for rs449647 A/A and rs405509 G/G genotypes (positive), and rs449647 A/T and rs405509 T/T genotypes (negative). Haplotype frequency estimation at the APOE locus showed significant associations for the ATG4, ATT4 and ACG3 (positive) and ATT2, ATT3 and TCG3 (negative) haplotypes. Therefore this study confirms the role of the rs449647 A/A genotype as risk factor for AD in Italy and suggests that promoter genotypes and APOE haplotypes might have a complex function in AD-associated genetic risk factors.     

Analysis and manipulation of neuronal gene expression using the Tα1 α-tubulin promoter

Analysis of the molecular genetic mechanisms underlying neuronal differentiation in mammals has been hampered by the lack of appropriate model systems. Here, we review the evidence that the Tα1 α-tubulin gene represents such a model system. The endogenous Tα1 gene is expressed at highly abundant levels during the growth of developing and mature neurons. In transgenic mice, 1·1 kb of 5′ flanking sequence from the Tα1 gene is sufficient to target gene expression to early developing neurons, and to regulate levels of expression as a function of neuronal growth. Analysis of this promoter has led to the initial elucidation of sequence elements essential for gene expression during neuronal development. Moreover, the Tα1 promoter provides an experimental mechanism for the manipulation and analysis of differentiating neurons in transgenic mice.