An enzyme-mediated bioorthogonal labeling method for genome-wide mapping of 5-hydroxymethyluracil.

DNA 5-hydroxymethyluracil (5hmU) is a thymine modification existing in the genomes of various organisms. The post-replicative formation of 5hmU occurs via hydroxylation of thymine by ten-eleven translocation (TET) dioxygenases in mammals and J-binding proteins (JBPs) in protozoans, respectively. In addition, 5hmU can also be generated through oxidation of thymine by reactive oxygen species or deamination of 5hmC by cytidine deaminase. While the biological roles of 5hmU have not yet been fully explored, determining its genomic location will highly assist in elucidating its functions. Herein, we report a novel enzyme-mediated bioorthogonal labeling method for selective enrichment of 5hmU in genomes. 5hmU DNA kinase (5hmUDK) was utilized to selectively install an azide (N3) group or alkynyl group into the hydroxyl moiety of 5hmU followed by incorporation of the biotin linker through click chemistry, which enabled the capture of 5hmU-containing DNA fragments via streptavidin pull-down. The enriched fragments were applied to deep sequencing to determine the genomic distribution of 5hmU. With this established enzyme-mediated bioorthogonal labeling strategy, we achieved the genome-wide mapping of 5hmU in Trypanosoma brucei. The method described here will allow for a better understanding of the functional roles and dynamics of 5hmU in genomes.

Identification of an orally active carbazole aminoalcohol derivative with broad-spectrum anti-animal trypanosomiasis activity.

Animal trypanosomiasis, caused by the members of subgenus Trypanozoon (Trypanosoma brucei brucei, T. evansi and T. equiperdum), has reduced animal productivity leading to significant negative economic impacts in endemic regions. Due to limited drug discovery and the emergence of drug-resistance over many recent decades, novel and effective compounds against animal trypanosomiasis are urgently required. This study was conducted to evaluate the antitrypanosomal potential of a batch of carbazole aminoalcohol derivatives. Among them, we found that the most effective compound was H1402, which exhibited potent trypanocidal efficacy against the bloodstream-form of T. b. brucei (EC50 = 0.73 ± 0.05 µM) and presented low cytotoxicity against two mammalian cell lines with CC50 > 30 µM. Using a murine model of acute infection, oral administration with H1402 demonstrated a complete clearance of T. b. brucei and all the infected mice were cured when they were treated twice daily for 5 days at a dose of 100 mg/kg. Furthermore, parasites were not detected in mice infected with T. evansi and T. equiperdum (the causative agents of surra and dourine, respectively, in animals) within 30 days following the same regimen with H1402. In addition, H1402 caused severe morphological and ultrastructural destruction to trypanosomes, as well as causing phosphatidylserine externalization, which are suggested to be the most likely cause of cell death. Overall, the present data demonstrated that H1402 could be promising as a rapid, safe and orally active lead compound for the development of new chemotherapeutics for animal trypanosomiasis.

The Occurrence of Malignancy in Trypanosoma brucei brucei by Rapid Passage in Mice.

Pleomorphic Trypanosoma brucei are best known for their tightly controlled cell growth and developmental program, which ensures their transmissibility and host fitness between the mammalian host and insect vector. However, after long-term adaptation in the laboratory or by natural evolution, monomorphic parasites can be derived. The origin of these monomorphic forms is currently unclear. Here, we produced a series of monomorphic trypanosome stocks by artificially syringe-passage in mice, creating snapshots of the transition from pleomorphism to monomorphism. We then compared these artificial monomorphic trypanosomes, alongside several naturally monomorphic T. evansi and T. equiperdum strains, with the pleomorphic T. brucei. In addition to failing to generate stumpy forms in animal bloodstream, we found that monomorphic trypanosomes from laboratory and nature exhibited distinct differentiation patterns, which are reflected by their distinct differentiation potential and transcriptional changes. Lab-adapted monomorphic trypanosomes could still be induced to differentiate, and showed only minor transcriptional differences to that of the pleomorphic slender forms but some accumulated differences were observed as the passages progress. All naturally monomorphic strains completely fail to differentiate, corresponding to their impaired differentiation regulation. We propose that the natural phenomenon of trypanosomal monomorphism is actually a malignant manifestation of protozoal cells. From a disease epidemiological and evolutionary perspective, our results provide evidence for a new way of thinking about the origin of these naturally monomorphic strains, the malignant evolution of trypanosomes may raise some concerns. Additionally, these monomorphic trypanosomes may reflect the quantitative and qualitative changes in the malignant evolution of T. brucei, suggesting that single-celled protozoa may also provide the most primitive model of cellular malignancy, which could be a primitive and inherent biological phenomenon of eukaryotic organisms from protozoans to mammals.

The oncoprotein HBXIP promotes human breast cancer growth through down-regulating p53 via miR-18b/MDM2 and pAKT/MDM2 pathways.

Mammalian hepatitis B X-interacting protein (HBXIP) is an 18-kDa protein that regulates a large number of transcription factors such as TF-IID, E2F1, SP1, STAT3, c-Myc, and LXR by serving as an oncogenic transcription coactivator and plays an important role in the development of breast cancer. We previously showed that HBXIP as an oncoprotein could enhance the promoter activity of MDM2 through coactivating p53, promoting the MDM2 transcription in breast cancer. In this study we investigated the molecular mechanisms underlying the modulation of MDM2/p53 interaction by HBXIP in human breast cancer MCF-7 cells in vitro and in vivo. We showed that HBXIP could up-regulate MDM2 through inducing DNA methylation of miR-18b, thus suppressing the miR-18b expression, leading to the attenuation of p53 in breast cancer cells. In addition, HBXIP could promote the phosphorylation of MDM2 by increasing the level of pAKT and bind to pMDM2, subsequently enhancing the interaction between MDM2 and p53 for the down-regulation of p53 in breast cancer cells. In MCF-7 breast cancer xenograft nude mice, we also observed that overexpression of HBXIP promoted breast cancer growth through the miR-18b/MDM2 and pAKT/MDM2 pathways. In conclusion, oncoprotein HBXIP suppresses miR-18b to elevate MDM2 and activates pAKT to phosphorylate MDM2 for enhancing the interaction between MDM2 and p53, leading to p53 degradation in promotion of breast cancer growth. Our findings shed light on a novel mechanism of p53 down-regulation during the development of breast cancer.

Synergistically mediated enhancement of cathodic and anodic electrochemiluminescence of graphene quantum dots through chemical and electrochemical reactions of coreactants.

We for the first time propose a new concept where a greater enhancement in dual potential electrochemiluminescence (ECL) of a single graphene quantum dot (GQD) emitter can be achieved through the coupling between chemical and electrochemical reactions of two different coreactants of K2S2O8 and Na2SO3.

miR-511 promotes the proliferation of human hepatoma cells by targeting the 3'UTR of B cell translocation gene 1 (BTG1) mRNA.

Aberrant expression of miR-511 is involved in the development of cancer, but the role of miR-511 in hepatocellular carcinoma (HCC) is not well documented. In this study, we explored the molecular mechanisms of miR-511 in hepatocarcinogenesis. Our results of bioinformatics analysis suggested that B cell translocation gene 1 (BTG1), a member of anti-proliferative gene family, was one of the putative targets of miR-511. The expression levels of miR-511 were significantly higher in 30 clinical HCC tissues than in corresponding peritumor tissues, and were negatively correlated with those of BTG1 in the HCC tissues (r=-0.6105, P<0.01). In human hepatoma cell lines HepG2 and H7402, overexpression of miR-511 dose-dependently inhibited the expression of BTG1, whereas knockdown of miR-511 dose-dependently increased the expression of BTG1. Luciferase reporter gene assays verified that miR-511 targeted the 3'UTR of BTG1 mRNA. In the hepatoma cells, overexpression of miR-511 significantly decreased BTG1-induced G1 phase arrest, which was rescued by overexpression of BTG1. Furthermore, overexpression of miR-511 promoted the proliferation of the hepatoma cells, which was rescued by overexpression of BTG1. Conversely, knockdown of miR-511 inhibited cell proliferation, which was reversed by knockdown of BTG1. In conclusion, miR-511 promotes the proliferation of human hepatoma cells in vitro by targeting the 3'UTR of BTG1 mRNA.

Preoperative serum fibrinogen is an independent prognostic factor in operable esophageal cancer.

In order to fully elucidate the association between serum fibrinogen and prognosis of esophageal cancer, we examined serum fibrinogen concentrations in 1512 patients who underwent esophagectomy by the Clauss method. The impact of fibrinogen on overall survival and disease-free survival was analyzed using the Kaplan-Meier method and Cox proportional hazard models. Hyperfibrinogenemia was significantly associated with older age, male gender, smoking, alcohol consumption, weight loss, advanced pathological T stage and lymph node metastasis. Patients with hyperfibrinogenemia exhibited poor OS (HR=1.20, 95%CI: 1.04-1.38, P=0.012) and DFS (HR=1.18, 95%CI: 1.03-1.35, P=0.019). Subgroup analysis further exhibited an significant association between hyperfibrinogenemia and poor OS (P<0.001), DFS (P<0.001) in esophageal squamous cell carcinoma (P<0.001) and early pathological stage (I-II) (P=0.001). Collectively, this study indicates that preoperative serum fibrinogen is an independent prognostic factor for survival in esophageal cancer.

Cryoprotective effects of low-density lipoproteins, trehalose and soybean lecithin on murine spermatogonial stem cells.

Spermatogonial stem cells (SSCs) have the ability to self-renew and offer a pathway for genetic engineering of the male germ line. Cryopreservation of SSCs has potential value for the treatment of male infertility, spermatogonial transplantation, and so on. In order to investigate the cryopreservation effects of different cryoprotectants on murine SSCs, 0.2 M of low-density lipoproteins (LDL), trehalose and soybean lecithin were added to the cryoprotective medium, respectively, and the murine SSCs were frozen at -80°C or -196°C. The results indicated that the optimal recovery rates of murine SSCs in the cryoprotective medium supplemented with LDL, trehalose and soybean lecithin were 92.53, 76.35 and 75.48% at -80°C, respectively. Compared with freezing at -196°C, the optimum temperature for improvement of recovery rates of frozen murine SSCs, cryopreservation in three different cryoprotectants at -80°C, were 17.11, 6.68 and 10.44% respectively. The recovery rates of murine SSCs in the cryoprotective medium supplemented with 0.2 M LDL were significantly higher than that of other cryoprotectants (P < 0.05). Moreover, the recovery rates were demonstrated to be greater at -80°C compared with at -196°C (P < 0.05). In conclusion, 0.2 M of LDL could significantly protect murine SSCs at -80°C. In the freezing-thawing process, LDL is responsible for the cryopreservation of murine SSCs because it can form a protective film at the surface of membranes. However, more research is needed to evaluate and understand the precise role of LDL during the freezing-thawing of SSCs.

High expression of transient potential receptor C6 correlated with poor prognosis in patients with esophageal squamous cell carcinoma.

TRPC6 plays a crucial role in the tumor progression of various cancers. The relation between the expression of TRPC6 and clinical prognosis has not been studied yet. Our study was to elucidate the role of TRPC6 in predicting outcomes of patients with esophageal squamous cell carcinoma (ESCC). Fresh frozen samples were collected immediately from 172 patients with ESCC after surgical resection from 2003 to 2008 at Sun Yat-sen University Cancer Center, including 45 pairs of tumor tissues and nontumor tissues. TRPC6 expression was measured by quantitative real-time PCR and Western blotting analyses. TRPC6 mRNA and protein were up-regulated in ESCC tissues when compared with the paired nontumor tissues. High expression of TRPC6 mRNA was associated with the higher pT status (P = 0.016) and pathological staging (P = 0.040). The 5-year disease-specific survival in the high expression of TRPC6 mRNA group (>188.98, n = 81) is poorer than that in low-level expression group (≤188.98, n = 91) (42.1 vs. 62.7 %, P = 0.004). Stratified analysis according to the pathological stage revealed its discernibility on DSS was only pronounced in patients with pStage III (P = 0.015). Cox multivariate analysis revealed that pN category (P < 0.001; Relative risk, 2.897, 95 % CI 1.830-4.585) and the expression of TRPC6 mRNA (P = 0.006; Relative risk, 1.863, 95 % CI 1.196-2.902) were independent prognostic factors. TRPC6 mRNA overexpression correlated with poor prognosis in patients with ESCC and might serve as a novel prognostic biomarker for resected ESCC patients in advanced stage.

Correlation of p53 status with the response to chemotherapy-based treatment in esophageal cancer: a meta-analysis.

BACKGROUND: The value of p53 status for predicting response to chemotherapy-based treatment in patients with esophageal cancer has been controversial. We conducted a meta-analysis to elucidate the correlation of p53 status with the response to chemotherapy-based treatment. METHODS: Studies were searched in PubMed, Embase, and Web of Science (up to September 2012). The p53 status and response to therapy were defined and standardized. Subgroup analyses based on the treatment and histopathology were performed to explore the usefulness of p53 status for predicting response to therapy in esophageal cancer. Sensitivity analyses were conducted by removing specific studies to assess the effects of study quality. RESULTS: We included 28 studies with 1497 cases in our meta-analysis. Wild-type form of p53 status (low expression of p53 protein and/or wild-type p53 gene) was associated with high response to chemotherapy-based treatment in esophageal cancer (total major response [MR]: risk ratio [RR] = 1.09, 95 % CI = 1.03-1.16, P = .003; pathological MR: RR = 1.15, 95 % CI = 1.06-1.25, P = .001; total complete response [CR]: RR = 1.08, 95 % CI = 1.00-1.17, P = .040). The similar correlation between the wild-type form p53 and response to therapy were also detected in subgroup analyses (total MR, pathological MR, and total CR in chemoradiotherapy subgroup; total MR in chemotherapy subgroup; total MR and pathological CR in esophageal squamous cell carcinoma [ESCC]). Additionally, patients with wild-type form p53 status had high pathological complete response rate to neoadjuvant chemoradiotherapy in ESCC. CONCLUSIONS: The current meta-analysis suggested that p53 status might be a predictive biomarker for response to chemotherapy-based treatment in esophageal cancer.