Great future or greedy venture: Precision medicine needs philosophy.

INTRODUCTION: Over the past decade, we have witnessed the initiation and implementation of precision medicine (PM), a discipline that promises to individualize and personalize medical management and treatment, rendering them ultimately more precise and effective. Despite of the continuing advances and numerous clinical applications, the potential of PM remains highly controversial, sparking heated debates about its future. METHOD: The present article reviews the philosophical issues and practical challenges that are critical to the feasibility and implementation of PM. OUTCOME: The explanation and argument about the relations between PM and computability, uncertainty as well as complexity, show that key foundational assumptions of PM might not be fully validated. CONCLUSION: The present analysis suggests that our current understanding of PM is probably oversimplified and too superficial. More efforts are needed to realize the hope that PM has elicited, rather than make the term just as a hype.

Anti-caries vaccine based on clinical cold-adapted influenza vaccine: A promising alternative for scientific and public-health protection against dental caries.

Dental caries remains one of the most pervasive infectious disease around the world. Protection against dental caries can be achieved experimentally by eliciting salivary IgA targeting surficial antigens of S. mutans, however, no such a vaccine has been launched for human use yet. Live vectored vaccines hold the greatest feasibility to induce potent and long-lasting immunity in the host. The FDA approved intranasal cold-adapted influenza vaccine has been used in clinical settings for many years. The vaccine can not only induce broad adaptive immune responses especially mucosal immunity, but the member strains can also circumvent existing immunity, presenting promising candidates for live vectored anti-caries vaccine. Moreover, the genetic techniques for modification of cold-adapted influenza viruses are well developed and widely applicable. Thus, we hypothesize that effective anti-caries vaccine can be developed with the backbone of cold-adapted influenza viruses by inserting specific antigenic identifier sequences of S. mutans into the viral genome, which is anticipated to protect against dental caries in humans with easy inoculation. The immune efficacies of recombinant cold-adapted influenza viruses expressing exogenous antigens have been verified by in vivo experiments for multiple infectious diseases, giving us great confidence to validate the safety properties and protection effect with this chimeric vaccine in animals or even humans. Existing data suggests that the live anti-caries vaccine may help improve public oral health by controlling the caries disease itself.

Concentrated growth factor exudate enhances the proliferation of human periodontal ligament cells in the presence of TNF­α.

The purpose of this study was to evaluate the effects of concentrated growth factor exudate (CGFe) on human periodontal ligament cells (hPDLCs) stimulated by tumor necrosis factor (TNF)­α. From the peripheral blood of healthy donors, CGFe was prepared according to the Sacco protocol after 7 days of incubation. The hPDLCs were cultured by a tissue explant method and identified with anti­vimentin and anti­cytokeratin antibodies. Cells were subjected to four different treatments: i) Control; ii) TNF­α (10 ng/ml); iii) CGFe (concentration 50%); and iv) CGFe+TNF­α. The proliferation of hPDLCs was measured with Cell Counting Kit­8 assays. Osteogenic differentiation and mineralization were determined by Alizarin Red S staining, alkaline phosphatase activity, western blotting and reverse transcription­quantitative polymerase chain reaction. CGFe enhanced cell proliferation and upregulated ALP activity, the mineralization level, and osteogenic­associated osteocalcin, runt­related transcription factor 2 and Osterix gene expression in hPDLCs under inflammatory conditions induced by TNF­α. The present study demonstrated that CGFe enhanced hPDLC proliferation and osteogenic differentiation in the presence of TNF­α­induced inflammation. As CGFe can be obtained from the venous blood of patients, it generates no immune reaction. Thus, it is more economical and beneficial to use CGFe in clinical periodontal regeneration practice than synthetic growth factors.

Platelet­rich fibrin exudate promotes the proliferation and osteogenic differentiation of human periodontal ligament cells in vitro.

The purpose of the present study was to evaluate the effects of platelet­rich fibrin (PRF) exudate on the proliferation, osteogenic differentiation and mineralization of human periodontal ligament cells (hPDLCs) in vitro. In the present study PRF was obtained with permission, from the peripheral blood of healthy donors and PRF exudates were collected on the 7th day of incubation. hPDLCs were obtained from healthy premolars, cultured by a tissue explant method and identified with anti­vimentin and anti­cytokeratin antibodies. PRF exudates were added to hPDLCs in different concentrations to evaluate cell proliferation and osteogenic differentiation. The proliferation of hPDLCs was measured using a colorimetric assay. Osteogenic differentiation and mineralization were determined by Alizarin red staining, alkaline phosphatase activity (ALP), western blotting and reverse transcription­quantitative polymerase chain reaction. Cell proliferation was enhanced by addition of the PRF exudate, which also promoted the formation of mineralized matrix nodules and upregulated ALP activity and osteoblast­associated levels of osteocalcin, runt­related transcription factor and osterix gene expression. As these stimulatory effects occurred in a dose­dependent manner, it was concluded that high concentrations of the PRF exudate served an essential role in the proliferation, osteogenic differentiation and mineralization of hPDLCs in vitro. The present study demonstrated that PRF exudate enhanced hPDLC proliferation, induced the osteoblastic differentiation of hPDLCs into mineralized tissue­formation cells in vitro, and may therefore provide potential benefits for periodontal tissue engineering; contributing to the primary processes of periodontal tissue regeneration. From the perspective of both economics and biology, PRF has greater clinical benefits than analogous growth factors.

Anticancer effect of exogenous hydrogen sulfide in cisplatin­resistant A549/DDP cells.

Despite huge advances in lung cancer treatment, resistance to cisplatin­based chemotherapy remains one of the major obstacles, and the elucidation of cisplatin resistance remains challenging. As an important biological and pharmacological mediator, hydrogen sulfide (H2S) performs a variety of homeostatic functions related to cancer formation and development. However, the effects of H2S on cisplatin­resistance lung cancer remain largely unknown. In the present study, we investigated the anticancer effects and relevant mechanisms of NaHS (an exogenous donor of H2S) on A549/DDP cells (cisplatin­resistant). The intracellular H2S was first evaluated using a fluorescence probe in A549 (cisplatin­sensitive) and A549/DDP cells. We found that H2S production was markedly decreased in A549/DDP cells compared with that in A549 cells, accomplished by the downregulation of cystathionine ß­synthase (CBS), an endogenous H2S­producing enzyme. In view of these findings, we then observed the effects of NaHS treatment on A549/DDP cells. The results showed that NaHS exposure exhibited an inhibitory effect on cell viability and the IC50 of cisplatin in A549/DDP cells decreased markedly during NaHS treatment (800 µmol/l). In addition, our data revealed that NaHS treatment of A549/DDP cells resulted in the induction of apoptosis, cell cycle arrest and inhibition of cell migration and invasion. Finally, we demonstrated that the marked changes in the A549/DDP cell response to NaHS may be triggered by the activation of p53, and overexpression of p21, caspase­3, Bax and MMP­2, as well as the downregulation of Bcl­xL. The findings of the present study provide novel evidence that NaHS administration may represent a new strategy for the treatment of cisplatin­resistant lung cancer.

Maternal Chronic Folate Supplementation Ameliorates Behavior Disorders Induced by Prenatal High-Fat Diet Through Methylation Alteration of BDNF and Grin2b in Offspring Hippocampus.

SCOPE: Maternal consumption of a high-fat diet (HFD) during pregnancy increases the risk of behavioral problems. Folate plays an important role in neuroplasticity and the preservation of neuronal integrity. This study aims at determining the influence of diets supplemented with folate on offspring behavior, and the mechanisms involved. METHODS AND RESULTS: Female mice were fed a control diet, an HFD, control diet supplemented with folate, or an HFD supplemented with folate for 5 weeks before mating. Open field task and elevated plus maze are used to evaluate the offspring behaviors. Results showed that offspring cognitive performance and anxiety-related behaviors, including those related to open field exploration and elevated plus maze, were significantly improved when dams were treated with folate in pregnancy. Moreover, the maternal folate supplement decreased BDNF and Grin2b methylation and upregulated their expressions in the brain of offspring, which were associated with decreasing the expression of DNA methyltransferases compared with those dams were treated only HFD in pregnancy. CONCLUSION: Maternal folate supplementation ameliorates behavior disorders induced by prenatal high-fat diet. The beneficial effects were associated with methylation and expression alteration of BDNF and Grin2b genes.

Lipopolysaccharide Downregulates Kruppel-Like Factor 2 (KLF2) via Inducing DNMT1-Mediated Hypermethylation in Endothelial Cells.

KLF2 plays a protective role in antiinflammation and endothelial function, and can be regulated by promoter methylation alteration. Lipopolysaccharide (LPS) is a mediator of inflammatory responses, which causes epigenetic change of certain genes in host cells. We thus aimed to determine whether LPS could control the KLF2 expression by inducing methylation in promoter region. DNA methylation of 16 CpG sites within KLF2 promoter region was detected by bisulfite sequencing PCR. Results showed that methylation at 12 CpG sites were significantly increased in HUVECs after exposure to LPS among the total 16 sites, and the average level was increased by 57%. The KLF2 expressions assessed by reverse transcription quantitative real-time PCR and Western blot were significantly downregulated compared that without LPS simulation. Moreover, both messenger RNA and protein levels of KLF2 in HUVEC co-treated with LPS and DNA methyltransferase (DNMT) 1 small interfering RNA were dramatically higher than that treated with LPS only. Similar result was obtained when the cells were incubated in combination with LPS and 5-aza-2'-deoxycytidine (AZA), suggesting that the reduction of KLF2 expression induced by LPS can be reversed by DNMT1 inhibition. Finally, the presence of AZA changed the expression of genes that depends on KLF2 in LPS-stimulated HUVECs, which downregulated the E-selectin and VCAM and increased the eNOS and thrombomodulin expression. Our data demonstrated that LPS exposure resulted in hypermethylation in KLF2 promoter in HUVECs, which subsequently led to downregulation of the KLF2 expression. The study suggested that epigenetic alteration is involved in LPS-induced inflammatory response and provided a new insight into atherogenesis.

Genetic Drivers of Kidney Defects in the DiGeorge Syndrome.

BACKGROUND: The DiGeorge syndrome, the most common of the microdeletion syndromes, affects multiple organs, including the heart, the nervous system, and the kidney. It is caused by deletions on chromosome 22q11.2; the genetic driver of the kidney defects is unknown. METHODS: We conducted a genomewide search for structural variants in two cohorts: 2080 patients with congenital kidney and urinary tract anomalies and 22,094 controls. We performed exome and targeted resequencing in samples obtained from 586 additional patients with congenital kidney anomalies. We also carried out functional studies using zebrafish and mice. RESULTS: We identified heterozygous deletions of 22q11.2 in 1.1% of the patients with congenital kidney anomalies and in 0.01% of population controls (odds ratio, 81.5; P=4.5×10-14). We localized the main drivers of renal disease in the DiGeorge syndrome to a 370-kb region containing nine genes. In zebrafish embryos, an induced loss of function in snap29, aifm3, and crkl resulted in renal defects; the loss of crkl alone was sufficient to induce defects. Five of 586 patients with congenital urinary anomalies had newly identified, heterozygous protein-altering variants, including a premature termination codon, in CRKL. The inactivation of Crkl in the mouse model induced developmental defects similar to those observed in patients with congenital urinary anomalies. CONCLUSIONS: We identified a recurrent 370-kb deletion at the 22q11.2 locus as a driver of kidney defects in the DiGeorge syndrome and in sporadic congenital kidney and urinary tract anomalies. Of the nine genes at this locus, SNAP29, AIFM3, and CRKL appear to be critical to the phenotype, with haploinsufficiency of CRKL emerging as the main genetic driver. (Funded by the National Institutes of Health and others.).

Methotrexate Induces Apoptosis of Postpartum Placental Cytotrophoblasts.

BACKGROUND: Though methotrexate (MTX) is known to inhibit proliferation of trophoblasts derived from ectopic and intrauterine pregnancies, its action on trophoblasts derived from postpartum placenta remains questionable. This study was designed to ascertain the efficacy of MTX in inducing cell death of postpartum placental cytotrophoblasts (PPTC). METHODOLOGY: Primary human cytotrophoblasts were isolated from placentae of 1st and 2nd trimester intrauterine pregnancies and from postpartum placentae. The isolated trophoblasts were identified based on the expression of cytokeratin 7. MTX-induced inhibition of proliferation of cytotrophoblasts was detected by flow cytometry combined with the WST-1 assay. Secretion of HCG-ß and invasiveness were evaluated to assess the effect of MTX on blocking the differentiated cellular function of cytotrophoblasts in relation to the gestational age. The efficacy of MTX in inducing apoptosis of cytotrophoblasts was estimated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling. RESULTS: MTX significantly inhibited the proliferation and differentiation of cytotrophoblasts. MTX-induced cell apoptosis of PPTC was confirmed by increased expression of Fas, FasL, Bax, cleaved caspases 3, 7, 8, and 9, and decreased expression of Bcl-2. CONCLUSION: MTX inhibits replication and differentiation of cytotrophoblasts and appears to be an efficient inducer of PPTC apoptosis.

Protective effects of maternal methyl donor supplementation on adult offspring of high fat diet-fed dams.

Obesity has become a global public health problem associated with metabolic dysfunction and chronic disorders. It has been shown that the risk of obesity and the DNA methylation profiles of the offspring can be affected by maternal nutrition, such as high-fat diet (HFD) consumption. The aim of this study was to investigate whether metabolic dysregulation and physiological abnormalities in offspring caused by maternal HFD can be alleviated by the treatment of methyl donors during pregnancy and lactation of dams. Female C57BL/6 mice were assigned to specific groups and given different nutrients (control diet, Control+Met, HFD and HFD+Met) throughout gestation and lactation. Offspring of each group were weaned onto a control diet at 3 weeks of age. Physiological (weight gain and adipose composition) and metabolic (plasma biochemical analyses) outcomes were assessed in male and female adult offspring. Expression and DNA methylation profiles of obesogenic-related genes including PPAR γ, fatty acid synthase, leptin and adiponectin were also detected in visceral fat of offspring. The results showed that dietary supplementation with methyl donors can prevent the adverse effects of maternal HFD on offspring. Changes in the expression and DNA methylation of obesogenic-related genes indicated that epigenetic regulation may contribute to the effects of maternal dietary factors on offspring outcomes.

Impact of prenatal polycyclic aromatic hydrocarbon exposure on behavior, cortical gene expression and DNA methylation of the Bdnf gene.

Prenatal exposure to polycyclic aromatic hydrocarbons (PAH) has been associated with sustained effects on the brain and behavior in offspring. However, the mechanisms have yet to be determined. We hypothesized that prenatal exposure to ambient PAH in mice would be associated with impaired neurocognition, increased anxiety, altered cortical expression of Bdnf and Grin2b, and greater DNA methylation of Bdnf. Our results indicated that during open-field testing, prenatal PAH exposed offspring spent more time immobile and less time exploring. Females produced more fecal boli. Offspring prenatally exposed to PAH displayed modest reductions in overall exploration of objects. Further, prenatal PAH exposure was associated with lower cortical expression of Grin2b and Bdnf in males, and greater Bdnf IV promoter methylation. Epigenetic differences within the Bdnf IV promoter correlated with Bdnf gene expression, but not with the observed behavioral outcomes, suggesting that additional targets may account for these PAH-associated effects.

Characterization of Hydroxymethylation Patterns in the Promoter of ß-globin Clusters in Murine Fetal Livers.

DNA methylation of 5-methylcytosine (5mC) is a key epigenetic regulator in mammals; the dynamic balance between methylation and demethylation affects the transcriptional activity of ß-globin. However, the dynamic cytosine methylation of ß-globin in vivo during the different stages of embryogenesis and in developing liver has not been fully established. 5-Hydroxymethylcytosine (5hmC) is a newly discovered epigenetic modification that is presumably generated by oxidation of 5mC by the ten-eleven translocation (TET) family and it has not been fully identified in ß-globin clusters. Here, we determined the 5hmC modifications in the promoter of murine ß-globin from fetal livers during normal embryonic development with the methods of bisulfite (BS) and oxidative bisulfite (oxBS)-based pyrosequencing techniques, with the combination of methylated DNA immunoprecipitation (MeDIP) and chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP-qPCR). The results characterized the 5hmC modification at the CpG sites of -426, -388, and -151 of ɛ(y) promoters and -50 and -487 CpG of ß(h1) from transcriptional start sites from E15.5 and E17.5 livers, while 5hmC modification was not observed in the adult ß-globin promoters. These observations were validated by the induction of TET transcription after being treated with a potent demethylating agent 5-azacytidine, and TET-mediated hydroxymethylation of ɛ(y) and ß(h1) from E13.5 livers was also confirmed in our study. These results suggested the 5hmC modification in promoters of ɛ(y) and ß(h1) and indicated that the 5hmC modification is essential for the ß-globin switching before the embryonic globin reactivation.

Prenatal polycyclic aromatic hydrocarbon, adiposity, peroxisome proliferator-activated receptor (PPAR) γ methylation in offspring, grand-offspring mice.

RATIONALE: Greater levels of prenatal exposure to polycyclic aromatic hydrocarbon (PAH) have been associated with childhood obesity in epidemiological studies. However, the underlying mechanisms are unclear. OBJECTIVES: We hypothesized that prenatal PAH over-exposure during gestation would lead to weight gain and increased fat mass in offspring and grand-offspring mice. Further, we hypothesized that altered adipose gene expression and DNA methylation in genes important to adipocyte differentiation would be affected. MATERIALS AND METHODS: Pregnant dams were exposed to a nebulized PAH mixture versus negative control aerosol 5 days a week, for 3 weeks. Body weight was recorded from postnatal day (PND) 21 through PND60. Body composition, adipose cell size, gene expression of peroxisome proliferator-activated receptor (PPAR) γ, CCAAT/enhancer-binding proteins (C/EBP) α, cyclooxygenase (Cox)-2, fatty acid synthase (FAS) and adiponectin, and DNA methylation of PPAR γ, were assayed in both the offspring and grand-offspring adipose tissue. FINDINGS: Offspring of dams exposed to greater PAH during gestation had increased weight, fat mass, as well as higher gene expression of PPAR γ, C/EBP α, Cox2, FAS and adiponectin and lower DNA methylation of PPAR γ. Similar differences in phenotype and DNA methylation extended through the grand-offspring mice. CONCLUSIONS: Greater prenatal PAH exposure was associated with increased weight, fat mass, adipose gene expression and epigenetic changes in progeny.

DNA methylation of heparanase promoter influences its expression and associated with the progression of human breast cancer.

Heparanase promotes tumor invasion and metastasis in several malignancies including breast cancer. However, the roles and regulation mechanisms of heparanase during breast cancer progression are still not fully understood. The aim of this study is to determine the differential regulation of heparanase gene expression in specific stages of breast cancer by DNA methylation. We detected levels of heparanase expression and DNA methylation patterns of its promoter in breast cancer cell lines (MCF-7 and MDA-MB-435) and clinical tissues, respectively. It has been observed that heparanase is highly expressed in the invasive MDA-MB-435 cells with low methylation modification in the heparanase promoter. In contrast, lower expression of heparanase in MCF-7 cells is accompanied by higher methylation in the promoter. Treatment of MCF-7 cells with 5-aza-2'-deoxycytidine (5-aza-dC), a potent demethylating agent, results in induction of heparanase expression and higher invasion potential in vitro and leads to an advantage of tumor formation in vivo. In 54 tissue samples, cancer samples at late stages (stage IV) showed the highest heparanase expression accomplished by little DNA methylation. On the contrary, methylation prevalence is highest in normal tissue and inversely correlated with heparanase expression. A significant correlation between DNA methylation and clinical stage was demonstrated (p = 0.012). Collectively, these results demonstrate that DNA methylation play the regulation role in heparanase gene in different stages of breast cancer and present a direct effect on tumor progression.

Effect of dynamic DNA methylation and histone acetylation on cPouV expression in differentiation of chick embryonic germ cells.

As a crucial pluripotency-related factor, the epigenetic regulation of Oct4 has been studied intensively in mammalians. However, its dynamic changes of DNA methylation and histone modification in avians remain poorly understood. In the present study, we first described the alterations of DNA methylation and histone acetylation in the promoter of chicken PouV (cPouV; the homologue of Oct4 in avian) during chick embryonic germ (EG) cell differentiation. The epigenetic modification analysis showed that DNA methylation in the cPouV promoter increased obviously, while histone acetylation decreased dramatically detected by chromatin immunoprecipitation assay in the process of differentiation. Gene expression analysis detection indicated that the levels of DNA methyltransferase 3a (Dnmt 3a), Dnmt 3b, and histone deacetylase 3 (HDAC 3) transcripts were significantly high, whereas the relative abundance of Dnmt 1, histone acetyltransferase (HAT), and cPouV mRNA was significantly decreased during the conversion of EG to embryoid body-like structures (EBs), which was correlated with the increased level of methylation and reduced level of H3 acetylation. Moreover, in vitro methylation assay indicated that the reporter gene was remarkably inhibited by the methylated promoter of cPouV. To further understand the effect of epigenetic modifiers on cPouV expression, we performed an analysis of EB cells treated with trichostatin A (TSA), Aza-2'-deoxycytidine (Aza), or TSA plus Aza (TSA/Aza). We observed that the effect of TSA/Aza is more sensitive to the reactivation of cPouV compared with TSA or Aza, indicating that these epigenetic inhibitors can function synergistically to facilitate the reprogramming process. The present study provided evidences that a critical role for cPouV activation/repression by DNA methylation and/or histone modifications is involved in the pluripotency maintenance and differentiation process of chick EG.

Human thyroxine binding globulin (TBG) promoter directs efficient and sustaining transgene expression in liver-specific pattern.

The liver performs a vital role in metabolic process, which makes it an attractive target organ for gene therapy. To improve the effects of gene therapy in disorders caused by metabolic disturbance, we quantitatively evaluated six promoters, CMV, EF1α, PGK, apoE, thyroxine binding globulin (TBG), and cytochrome P450 2E1 (CYP2E1) by measuring the expression of α1-antitrypsin, which is controlled by these promoters and introduced via a lentivirus-mediated delivery system in the liver. The results showed that the TBG promoter presents as highly active though in general it is slightly lower than the ubiquitous CMV and EF1α. The expression of exogenous genes driven by the TBG promoter demonstrates to be much higher than by PGK, apoE, and CYP2E1 promoters, and the fragment of -435bp to -26bp from transcription start site (TSS) in the TBG promoter region is identified as the optimum region to direct transgene expression at a higher level. In addition, we further confirmed that the TBG promoter confers transgene persistent and specific expression within the liver up to several months after integration. The data suggests that the TBG promoter is a valuable tool and will greatly facilitate the optimization of vector design in hepatic gene therapy.

Association between mitochondrial DNA haplotype compatibility and increased efficiency of bovine intersubspecies cloning.

Reconstructed embryos derived from intersubspecies somatic cell nuclear transfer (SCNT) have poorer developmental potential than those from intrasubspecies SCNT. Based on our previous study that Holstein dairy bovine (HD) mitochondrial DNA (mtDNA) haplotype compatibility between donor karyoplast and recipient cytoplast is crucial for SCNT embryo development, we performed intersubspecies SCNT using HD as donor karyoplast and Luxi yellow heifer (LY) as recipient cytoplast according to mtDNA haplotypes determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. The results demonstrated that intersubspecies mtDNA homotype SCNT embryos had higher pre- and post-implantation developmental competence than intrasubspecies mtDNA heterotype embryos as well as improved blastocyst reprogramming status, including normal H3K9 dimethylation pattern and promoter hypomethylation of pluripotent genes such as Oct4 and Sox2, suggesting that intersubspecies SCNT using LY oocytes maintains HD cloning efficiency and may reprogram HD nuclei to develop into a normal cloned animal ultimately. Our results indicated that karyoplast-cytoplast interactions and mtDNA haplotype compatibility may affect bovine intersubspecies SCNT efficiency. This study on bovine intersubspecies SCNT is valuable for understanding the mechanisms of mtDNA haplotype compatibility between karyoplast and cytoplast impacting the bovine SCNT efficiency, and provides an alternative and economic resource for HD cloning.

p53 status and its prognostic role in extrahepatic bile duct cancer: a meta-analysis of published studies.

The dysfunction of p53 is the most common genetic alteration in human cancer. A variety of studies have investigated the clinicopathologic correlation of p53 and its impact on patient survival in different types of cancer. For extrahepatic bile duct cancer (EBDC), however, the results were limited and conflicting. In this study, we performed an investigation to confirm whether there was a correlation between p53 status and some routine parameters. To further observe the impact of p53 on the survival of EBDC patients, a meta-analysis based on published studies was conducted. Candidate studies were searched from PubMed, EMBASE, and ISI Web of Science. Our results demonstrated that there were significant correlations between p53 expression and some clinicopathological parameters. Furthermore, the pooled results of the meta-analysis showed that the combined hazard ratio (HR) estimate for overall survival (OS) was 1.53 (95% CI, 1.10-2.14) and 1.23 (95% CI, 0.93-1.75) in univariate and multivariate analysis, respectively. In conclusion, the high level of p53 appears to be an effective prognostic factor to OS of EBDC patients. However, some limitations unavoidable in this meta-analysis and problems of previous p53 studies in EBDC mean that further studies are necessary before significant conclusions can be made.

Donor-host mitochondrial compatibility improves efficiency of bovine somatic cell nuclear transfer.

BACKGROUND: The interaction between the karyoplast and cytoplast plays an important role in the efficiency of somatic cell nuclear transfer (SCNT), but the underlying mechanism remains unclear. It is generally accepted that in nuclear transfer embryos, the reprogramming of gene expression is induced by epigenetic mechanisms and does not involve modifications of DNA sequences. In cattle, oocytes with various mitochondrial DNA (mtDNA) haplotypes usually have different ATP content and can further affect the efficiency of in vitro production of embryos. As mtDNA comes from the recipient oocyte during SCNT and is regulated by genes in the donor nucleus, it is a perfect model to investigate the interaction between donor nuclei and host oocytes in SCNT. RESULTS: We investigated whether the in vitro development of reconstructed bovine embryos produced by SCNT would be influenced by mtDNA haplotype compatibility between the oocytes and donor cells. Embryos from homotype A-A or B-B showed significantly higher developmental ability at blastocyst stages than the heterotype A-B or B-A combinations. Post-implantation development ability, pregnancy rate up to day 90 of gestation, as well as percent of term births were higher in the homotype SCNT groups than in the heterotype groups. In addition, homotype and heterotype SCNT embryos showed different methylation patterns of histone 3-lysine 9 (H3K9) genome-wide and at pluripotency-related genes (Oct-4, Sox-2, Nanog). CONCLUSION: Both histone and DNA methylation show that homotype SCNT blastocysts have a more successful epigenetic asymmetry pattern than heterotype SCNT blastocysts, which indicates more complete nuclear reprogramming. This may result from variability in their epigenetic patterns and responses to nuclear reprogramming. This suggests that the compatibility of mtDNA haplotypes between donor cells and host oocytes can significantly affect the developmental competence of reconstructed embryos in SCNT, and may include an epigenetic mechanism.

Association of differential and site-dependent CpG methylation and diverse expression of DNA methyltransferases with the tissue-specific expression of human beta-globin gene in transgenic mice.

Expression of human locus control region (LCR) and beta-globin promoter has been recognized as an important factor in time- and tissue-specific expression event. DNA methylation can affect the transcriptional activity of specific genes. To investigate the methylation mechanism in the regulation of LCR and promote expression, this study used a transgenic mouse strain generated previously, in which the hematopoietic-specific expression of the EGFP was driven by human beta-globin promoter and under the control of LCR, to examine the CpG methylation pattern in various tissues. The results showed the inverse correlation between the methylated extent and the levels of gene expression in all tested tissues. We also found that the methylated extent of the 10 examined CpG sites was biased along their positions and is more efficient near the transcription start site. Real-time quantitative RT-PCR analysis of DNA methyltransferases (DNMTs) transcripts showed that Dnmt3a and Dnmt3b expressed with a very low level in the hematopoietic tissues that was coincident with the relative higher EGFP expression in these tissues, indicating that the differential expression of DNMTs contributed to the tissue-specific methylated patterns which caused the diverse gene expression in various tissues. These findings provide significant clues to elucidate the mechanism of the regulation on tissue-specific expression of genes.