Construction of a label-free fluorescent biosensor for homogeneous detection of m6A eraser FTO in breast cancer tissues.

Fat mass and obesity-associated protein (FTO) is a crucial eraser of RNA N6- methyladenosine (m6A) modification, and abnormal FTO expression level is implicated in pathogenesis of numerous cancers. Herein, we demonstrate the construction of a label-free fluorescent biosensor for homogeneous detection of m6A eraser FTO in breast cancer tissues. When FTO is present, it specifically erases the methyl group in m6A, inducing the cleavage of demethylated DNA by endonuclease DpnII and the generation of a single-stranded DNA (ssDNA) with a 3'-hydroxyl group. Subsequently, terminal deoxynucleotidyl transferase (TdT) promotes the incorporation of dTTPs into the ssDNA to obtain a long polythymidine (T) DNA sequence. The resultant long poly (T) DNA sequence can act as a template to trigger hyperbranched strand displacement amplification (HSDA), yielding numerous DNA fragments that may be stained by SYBR Gold to produce an enhanced fluorescence signal. This biosensor processes ultrahigh sensitivity with a detection limit of 1.65 × 10-10 mg/mL (2.6 fM), and it can detect the FTO activity in a single MCF-7 cell. Moreover, this biosensor can screen the FTO inhibitors, evaluate enzyme kinetic parameters, and discriminate the FTO expression levels in the tissues of breast cancer patients and healthy persons.

Naringin ameliorates liver fibrosis in zebrafish by modulating IDO1-mediated lipid metabolism and inflammatory infiltration.

Liver fibrosis (LF) is an important reparative process in response to acute or chronic hepatic injury, which has the potential to advance towards cirrhosis and hepatocellular carcinoma. Dietary naringin consumption contributes to protection against LF in animal studies, while the exact protective mechanism of naringin remains unclear. This study aimed to investigate the molecular mechanisms behind the potential protective effect of naringin against TAA-induced LF in zebrafish. In this study, we utilized zebrafish to create the LF model and investigate the therapeutic mechanism of naringin. Firstly, we evaluated the changes in hepatic fibrosis and lipid accumulation in the liver following naringin treatment with oil red O, Nile red, and Sirius red and immunohistochemistry. In addition, we employed an ROS probe to directly measure oxidative stress and monitor inflammatory cell migration in a zebrafish transgenic line. Morpholino was used in the knockdown of IDO1 in order to verify its vital role in LF. Our findings demonstrated that naringin exhibited anti-inflammatory and anti-fibrotic action in conjunction with a reversal in lipid accumulation, oxidative stress and suppression of macrophage infiltration and activation of hepatic stellate cells. Furthermore, the results showed that the antifibrotic effect of naringin was removed upon IDO1 knockdown, proving that naringin exerts a protective effect by regulating IDO1. Naringin demonstrates remarkable protective effects against LF, effectively counteracting inflammation and hepatic steatosis in zebrafish liver. These findings suggest that naringin may function as an effective IDO1 inhibitor, holding the potential for clinical translation as a therapeutic agent for the treatment of LF.

Development of a N6-methyladenosine-directed single quantum dot-based biosensor for sensitive detection of METTL3/14 complex activity in breast cancer tissues.

The METTL3/14 complex is an important RNA N6-Methyladenosine (m6A) methyltransferase in organisms, and the abnormal METTL3/14 complex activity is associated with the pathogenesis and various cancers. Sensitive detection of METTL3/14 complex is essential to tumor pathogenesis study, cancer diagnosis, and anti-cancer drug discovery. However, traditional methods for METTL3/14 complex assay suffer from poor specificity, costly antibodies, unstable RNA substrates, and low sensitivity. Herein, we construct a single quantum dot (QD)-based förster resonance energy transfer (FRET) biosensor for sensitive detection of METTL3/14 complex activity. In the presence of METTL3/14 complex, it catalyzes the methylation of adenine in the substrate probe, leading to the formation of m6A that protects the substrate probes from MazF-mediated cleavage. The hybridization of methylated DNA substrate with biotinylated capture probe initiates polymerization reaction to obtain a biotinylated double-stranded DNA (dsDNA) with the incorporation of numerous Cy5 fluorophores. Subsequently, the Cy5-incorporated dsDNA can self-assembly onto the 605QD surface to form the 605QD-dsDNA-Cy5 nanostructure, causing FRET between 605QD donor and Cy5 acceptor. This biosensor has excellent sensitivity with a limit of detection (LOD) of 3.11 × 10-17 M, and it can measure the METTL3/14 complex activity in a single cell. Moreover, this biosensor can be used to evaluate the METTL3/14 complex kinetic parameters and screen potential inhibitors. Furthermore, it can differentiate the METTL3/14 complex expression in healthy human tissues and breast cancer patient tissues, providing a powerful tool for cancer pathogenesis study, clinical diagnosis, prognosis monitoring, and drug discovery.

A simple and rapid mix-and-read assay for sensitive detection of O6-methylguanine DNA methyltransferase.

We have developed a simple and rapid mix-and-read assay for the sensitive detection of O6-methylguanine DNA methyltransferase (MGMT) activity based on exonuclease III-assisted signal amplification under completely isothermal conditions (37 °C). This method is very simple and rapid (60 min) with ultrahigh sensitivity and good specificity, and it can detect MGMT activity at the single-cell level. Moreover, this method can be applied for the screening of MGMT inhibitors and the discrimination of MGMT in different cancer cells.

Construction of a dephosphorylation-mediated chemiluminescent biosensor for multiplexed detection of DNA glycosylases in cancer cells.

DNA glycosylases are engaged in the base excision repair process and play a vital role in maintaining genomic integrity. It remains a challenge for multiplexed detection of DNA glycosylases in cancer cells. Herein, we demonstrate the construction of a dephosphorylation-mediated chemiluminescent biosensor for multiplexed detection of human alkyladenine DNA glycosylase (hAAG) and uracil DNA glycosylase (UDG) in cancer cells. In this biosensor, the generation of chemiluminescence signals relies on the dephosphorylation of 3-(2'-spiroadamantyl)-4-methoxy-4-(3''-phosphoryloxyphenyl)-1,2-dioxetane (AMPPD) catalyzed by alkaline phosphatase (ALP). We design a bifunctional double-stranded DNA (dsDNA) substrate, a biotin-labelled poly-(T) probe, and two capture probes for the hAAG and UDG assay. This assay involves four steps including (1) the cleavage of the bifunctional dsDNA substrate induced by DNA glycosylases, (2) the recognition of the 3'-OH terminus of the primer by TdT and the subsequent TdT-mediated polymerization reaction, (3) the construction of the AuNPs-dsDNA-ALP nanostructures, and (4) the streptavidin-alkaline phosphatase (SA-ALP)-initiated dephosphorylation of AMPPD for the generation of an enhanced chemiluminescence signal. By taking advantage of the unique features of TdT-mediated polymerization and the intrinsic superiority of the ALP-AMPPD-based chemiluminescence system, this biosensor exhibits good specificity and high sensitivity with a detection limit of 1.53 × 10-6 U mL-1 for hAAG and 1.77 × 10-6 U mL-1 for UDG, and it can even quantify multiple DNA glycosylases at the single-cell level. Moreover, this biosensor can be applied for the measurement of kinetic parameters and the screening of DNA glycosylase inhibitors, holding great potential in DNA damage-related biomedical research and disease diagnostics.

Effect of Gender and Age on the Correlation between Helicobacter pylori and Colorectal Adenomatous Polyps in a Chinese Urban Population: A Single Center Study.

OBJECTIVES: To investigate whether Helicobacter pylori (H. pylori) infection increases the risk of colorectal adenomatous polyp (CAP) in the context of age and gender. METHODS: A total of 563 study subjects (male/female, 368/195) from Beijing, China, with higher nursing level who underwent colonoscopy were retrospectively collected. H. pylori and CAP were detected by carbon-13 urea breath test and colorectal colonoscopy. The correlations between the number, size, distribution, and pathological grade of CAP and H. pylori infection were analyzed. The population was further stratified by age and gender in order to examine the risk of H. pylori and CAP in the context of these variables. The influence of H. pylori on the risk of CAP was assessed by logistic regression model. RESULTS: 315 participants were diagnosed with CAP, and 207 participants were classified as healthy controls. The prevalence of H. pylori in the CAP group was significantly higher than that in the healthy control group (119/315, 37.8% versus 44/207, 21.3%) (p < 0.001). The proportion of H. pylori positive plus CAP in participants <50 years old was significantly higher than that in participants >50 years old (87/250; 34.8% versus 32/65; 49.2%) (p < 0.001). The proportion of H. pylori positive plus CAP in participants <50 years old was significantly higher than that in participants >50 years old (87/250; 34.8% versus 32/65; 49.2%) (p < 0.001). The proportion of H. pylori positive plus CAP in participants <50 years old was significantly higher than that in participants >50 years old (87/250; 34.8% versus 32/65; 49.2%) (p < 0.001). The proportion of H. pylori positive plus CAP in participants <50 years old was significantly higher than that in participants >50 years old (87/250; 34.8% versus 32/65; 49.2%) (. CONCLUSIONS: H. pylori is a major risk factor for CAP. Further studies are needed to assess the effects of H. pylori treatment or persistent infection on the occurrence or recurrence of CAP.

Exogenous testosterone alleviates cardiac fibrosis and apoptosis via Gas6/Axl pathway in the senescent mice.

BACKGROUND: Androgen has been implicated in aging-related cardiac remodeling, but its precise role in aging heart remains controversial. We aimed to investigate the role of testosterone in the development of aging-related cardiac remodeling and the mechanisms involved. METHODS: Wild type and Axl knockout mice (Axl-/-) were randomized into three groups: the young group (n = 30, 3 months old), the aging group (n = 30, 18 months old), the testosterone undecanoate treatment group (TU, n = 30, 18 months old). Mice in the TU group were given testosterone undecanoate (39 mg/kg) by subcutaneous injection on the back at fifteen-months-old, once a month, a total of three times. The old group received solvent reagent (corn oil) by the same method. RESULTS: The aging mice exhibited a decrease in serum testosterone, and Gas6 levels and an increase in apoptosis, and manifested cardiac fibrosis. Testosterone injection to wild type mice increased the levels of testosterone and Gas6 in serum and decreased cardiac apoptosis and fibrosis. Axl-/-mice receiving testosterone injection exhibited no obvious improvement in cardiac remodeling although the levels of testosterone and Gas6 in serum elevated. CONCLUSIONS: These data indicated that testosterone replacement therapy (TRT) alleviates cardiac fibrosis and apoptosis, at least in part by enhancing Gas6 expression. Moreover, deletion of Axl disables testosterone, which indicated that Axl is an important downstream regulator of testosterone. TRT would improve aging-related cardiac remolding via Gas6/Axl signaling pathway, implicating its therapeutic potential to treat aging-related heart disease.

Artesunate induces apoptosis and autophagy in HCT116 colon cancer cells, and autophagy inhibition enhances the artesunate­induced apoptosis.

The present study assessed the antitumor effect of artesunate (ART) in vitro and in vivo, as well as its underlying mechanism of action in HCT116 colon cancer cells. An MTT assay, DAPI staining, flow cytometry, western blotting, immunohistochemistry, transmission electron microscopy and TUNEL assay were performed to study the molecular mechanism underlying the antitumor effects of ART in HCT116 colon cancer cells. ART was observed to inhibit proliferation by inducing the apoptosis of HCT116 cells both in vitro and in vivo. Flow cytometry analysis demonstrated that treatment with 2 and 4 µg/ml ART for 48 h induced early apoptosis in 22.7 and 33.8% of cells, respectively. In the xenograft tumors of BALB/c nude mice, TUNEL­positive cells increased in the ART group compared with that in the normal saline group. Furthermore,the associated mitochondrial cleaved­caspase 3, poly­ADP ribose polymerase (PARP), caspase 9 and Bcl­2­associated X protein levels increased while B­cell lymphoma­2 (Bcl­2) decreased both in the cell and animal ART­treated group. ART­treated cells also exhibited autophagy induction, as evidenced by increased protein expression levels of light chain 3 (LC3) and beclin­1, and the presence of autophagosomes. Notably, pharmacological blockade of autophagy activation using hydroxychloroquine markedly enhanced ART­induced apoptosis and increased the protein levels of cleaved caspase 3 and PARP, while decreasing the levels of LC3 and beclin­1. These findings suggested that the ART­induced autophagy may have a cytoprotective effect by suppressing apoptosis. In conclusion, ART may be a potentially clinically useful anticancer drug for human colon cancer. In addition, co­treatment with ART and an autophagy inhibitor may be an effective anticancer therapy.

Integration of isothermal amplification with quantum dot-based fluorescence resonance energy transfer for simultaneous detection of multiple microRNAs.

MicroRNAs (miRNAs) are small non-coding RNAs that regulate important physiological processes, and their dysregulation is associated with various human diseases. Simultaneous sensitive detection of multiple miRNAs may facilitate early clinical diagnosis. In this research, we demonstrate for the first time the integration of hyperbranched rolling circle amplification (HRCA) with quantum dot (QD)-based fluorescence resonance energy transfer (FRET) for the simultaneous detection of multiple microRNAs with a single-color QD as the donor and two fluorescent dyes as the acceptors. We used miR-21 and miR-221 as target miRNAs. We designed two circular templates which may specifically hybridize with miR-21 and miR-221, respectively, for the initiation of the HRCA reaction. The products of the HRCA reaction may hybridize with both capture probes and reporter probes to form the biotinylated acceptor-labeled sandwich hybrids. The resultant sandwich hybrids can assemble on the surface of the QD, enabling efficient FRET between the QD and the acceptors, with the Cy3 signal indicating the presence of miR-21 and the Texas Red signal indicating the presence of miR-221. This assay has significant advantages of simplicity and low cost. The HRCA reaction can be performed under isothermal conditions with the same reverse primer for different target miRNAs, and the products of the HRCA reaction for both miR-21 and miR-221 can specifically hybridize with the same capture probes. This assay exhibits excellent specificity and high sensitivity with a detection limit of 7.2 × 10-16 M for miR-21 and 1.6 × 10-17 M for miR-221, and it can be used for simultaneous detection of multiple miRNAs in human cancer cells, holding great potential in biomedical research and clinical diagnosis.

Simultaneous sensitive detection of multiple DNA glycosylases from lung cancer cells at the single-molecule level.

DNA glycosylases are involved in the base excision repair pathway, and all mammals express multiple DNA glycosylases to maintain genome stability. However, the simultaneous detection of multiple DNA glycosylase still remains a great challenge. Here, we develop a single-molecule detection method for the simultaneous detection of human 8-oxoguanine DNA glycosylase 1 (hOGG1) and human alkyladenine DNA glycosylase (hAAG) on the basis of DNA glycosylase-mediated cleavage of molecular beacons. We designed a Cy3-labeled molecular beacon modified with 8-oxoguanine (8-oxoG) for a hOGG1 assay and a Cy5-labeled molecular beacon modified with deoxyinosine for a hAAG assay. hOGG1 may catalyze the removal of 8-oxoG from 8-oxoG/C base pairs to generate an apurinic/apyrimidinic (AP) site, and hAAG may catalyze the removal of deoxyinosine from deoxyinosine/T base pairs to generate an AP site. With the assistance of apurinic/apyrimidinic endonuclease (APE1), the cleavage of AP sites results in the cleavage of molecular beacons, with Cy3 indicating the presence of hOGG1 and Cy5 indicating the presence of hAAG. Both of the Cy3 and Cy5 signals can be simply quantified by total internal reflection fluorescence-based single-molecule detection. This method can simultaneously detect multiple DNA glycosylases with a detection limit of 2.23 × 10-6 U µL-1 for hOGG1 and 8.69 × 10-7 U µL-1 for hAAG without the involvement of any target amplification. Moreover, this method can be used for the screening of enzyme inhibitors and the simultaneous detection of hOGG1 and hAAG from lung cancer cells, having great potential for further application in early clinical diagnosis.

Ginsenoside Rb1 enhances atherosclerotic plaque stability by skewing macrophages to the M2 phenotype.

Atherosclerosis (AS) is characterized as progressive arterial plaque, which is easy to rupture under low stability. Macrophage polarization and inflammation response plays an important role in regulating plaque stability. Ginsenoside Rb1 (Rb1), one of the main active principles of Panax Ginseng, has been found powerful potential in alleviating inflammatory response. However, whether Rb1 could exert protective effects on AS plaque stability remains unclear. This study investigated the role of Rb1 on macrophage polarization and atherosclerotic plaque stability using primary peritoneal macrophages isolated from C57BL/6 mice and AS model in ApoE-/- mice. In vitro, Rb1 treatment promoted the expression of arginase-I (Arg-I) and macrophage mannose receptor (CD206), two classic M2 macrophages markers, while the expression of iNOS (M1 macrophages) was decreased. Rb1 increased interleukin-4 (IL-4) and interleukin-13 (IL-13) secretion in supernatant and promoted STAT6 phosphorylation. IL-4 and/or IL-13 neutralizing antibodies and leflunomide, a STAT6 inhibitor attenuated the up-regulation of M2 markers induced by Rb1. In vivo, the administration of Rb1 promoted atherosclerotic lesion stability, accompanied by increased M2 macrophage phenotype and reduced MMP-9 staining. These data suggested that Rb1 enhanced atherosclerotic plaque stability through promoting anti-inflammatory M2 macrophage polarization, which is achieved partly by increasing the production of IL-4 and/or IL-13 and STAT6 phosphorylation. Our study provides new evidence for possibility of Rb1 in prevention and treatment of atherosclerosis.