Proximity ligation-transcription circuit-powered exponential amplifications for single-molecule monitoring of telomerase in human cells.

We develop a new strategy for single-molecule monitoring of telomerase based on proximity ligation-transcription circuit-powered exponential amplifications. This strategy exhibits high sensitivity with a detection limit of 0.1 aM for the synthetic telomerase product TPC4 in vitro and 1 HeLa cell in vivo. Moreover, it can screen potential inhibitors, discriminate telomerase from interferents, and distinguish cancer cells from normal cells.

The Mediating Role of Resilience and Self-Esteem Between Life Events and Coping Styles Among Rural Left-Behind Adolescents in China: A Cross-Sectional Study.

Objective: This study aims to explore the association between life events and coping styles, and how resilience and self-esteem mediate the association. Methods: A cross-sectional study was conducted among 981 left-behind adolescents (LBAs) in five junior high schools in Hunan Province, China, from April 13 to April 20, 2020. We utilized self-designed sociodemographic questionnaire, Adolescent Self-Rating Life Events Checklist, Resilience Scale Chinese Adolescent, Rosenberg Self-Esteem Scale, and Simplified Coping Style Questionnaire to assess the mental health of LBAs. Statistic description, Pearson correlation analysis, and structural equation model were adopted to analyze the data. Results: Results revealed that life events could negatively predict resilience (ß = -0.29, P < 0.001) and self-esteem (ß = -0.39, P < 0.001) and positively predict LBAs' positive coping style (ß = 0.28, P < 0.001) and negative coping style (ß = 0.21, P < 0.001). Self-esteem could also positively predict the resilience of LBAs (ß = 0.62, P < 0.001); resilience could negatively predict the negative coping style (ß = -0.21, P < 0.001) and positively predict the positive coping style (ß = 0.79, P < 0.001). Life events not only have direct effects on negative coping style (ß = 0.21) and positive coping style (ß = 0.28) but also have indirect effects on coping styles by affecting resilience (ß = -0.29) and self-esteem (ß = -0.39). The total effect of life events on coping styles was 0.32, where 34.37% was mediated by resilience and self-esteem. Conclusion: We proved that resilience and self-esteem mediated most of the effects of life events on coping styles. The findings had important implications for interventions to promote mental health of LBAs, particularly the enhancement of resilience and self-esteem.

Effects of transtheoretical model-based intervention on the self-management of patients with an ostomy: A randomised controlled trial.

AIMS AND OBJECTIVES: To determine the effect of a transtheoretical model (TTM)-based intervention on patients with an ostomy and provide patient-centred, accessible assistance and dynamic education to improve patient self-management. BACKGROUND: Proper self-management may promote the rehabilitation of patients with an ostomy. TTM-based interventions have resulted in positive health behavioural changes. DESIGN: Randomised controlled trial performed according to the CONSORT guidelines. SUBJECT AND SETTING: The sample comprised 55 men and 37 women (24-77 years old, mean ± SD = 52.8 ± 11.13 years). The study settings included three tertiary hospitals in Changsha, Hunan, China. METHODS: The 92 patients, recruited from August 2012 to March 2013, were randomised into a control group and an intervention group. Randomisation was done by using a block randomisation list with a block size of 4. Self-management behaviours were assessed at the baseline, 2 days before discharge and after 1, 3 and 6 months of follow-up. The chi-squared test, independent sample t test and repeated measures analysis of variance were used to analyse the data. RESULTS: Patients in the intervention group were more likely to be at the action and maintenance stages compared with those in the control group. We also observed significant improvements in the self-management ability in the process of change, the decisional balance and self-efficacy in the intervention group compared with those in the control group after four intervention sessions and up to 6 months of follow-up. No serious intervention-related adverse events were observed. CONCLUSIONS: The TTM-based intervention had positive effects on self-management behaviours of patients with an ostomy. RELEVANCE TO CLINICAL PRACTICE: The TTM-based intervention had positive effects on self-management behaviours of patients with an ostomy and may provide a reference for health providers to develop behaviour promotion programmes to improve the self-management of patients with an ostomy.

Calcium-Polystyrene Sulfonate Decreases Inter-Dialytic Hyperkalemia in Patients Undergoing Maintenance Hemodialysis: A Prospective, Randomized, Crossover Study.

Hyperkalemia is a life-threatening emergency in maintenance hemodialysis (MHD) patients. This clinical trial investigated the efficacy and safety of calcium-polystyrene sulfonate (Ca-PS) in MHD patients with interdialytic hyperkalemia. A total of 58 hemodialysis patients with hyperkalemia (≥5.5 mol/L) were selected and administered either a 3-week Ca-PS (3 × 5 g/day) or a blank control following the model of a prospective, randomized, crossover clinical trial with a 1-week washout period. All patients were followed up for another 3 weeks for safety evaluations. The primary outcome was the magnitude of the change in serum potassium levels. The secondary outcomes were electrocardiography (ECG) changes and treatment safety (volume overload, electrolyte imbalance). Compared with the control group, Ca-PS treatment significantly reduced serum potassium levels (P <0.01). More patients in the Ca-PS group had lower serum potassium levels than the safety level of <5.5 mmol/L (32% for control vs. 61% for Ca-PS, P <0.01). Peaked T-wave occurred less frequently in patients in the Ca-PS group (13.8% for Ca-PS vs. 31.03% for control, P <0.01). In addition, Ca-PS reduced serum phosphorus levels with no effects on serum levels of calcium and sodium, fluid volume, blood pressure, or interdialytic weight gain. Ca-PS treatment decreases serum levels of potassium and phosphorus in MHD patients with interdialytic hyperkalemia. Ca-PS does not induce volume overload or disrupt electrolyte balance.

Aspergoterpenins A⁻D: Four New Antimicrobial Bisabolane Sesquiterpenoid Derivatives from an Endophytic Fungus Aspergillus versicolor.

Aspergoterpenins A⁻D (1⁻4), four new bisabolane sesquiterpenoid derivatives, were obtained from the endophytic fungus, Aspergillus versicolor, together with eight known compounds (5⁻12), and their structures were elucidated by a comprehensive analysis of their NMR (Nuclear Magnetic Resonance), MS (Mass Spectrum) and CD (Circular Dichroism) spectra. Aspergoterpenin A (1) was the first example with a characteristic ketal bridged-ring part in the degraded natural bisabolane-type sesquiterpene structures. The compounds 1⁻12 displayed no significant activities against four cancer cell lines (A549, Caski, HepG2 and MCF-7). Further, the antimicrobial activities to Erwinia carotovora sub sp. Carotovora were evaluated, and the results showed that compounds 1⁻12 displayed antimicrobial activities with MIC values ranging from 15.2 to 85.2 µg/mL.

Penicitroamide, an Antimicrobial Metabolite with High Carbonylization from the Endophytic Fungus Penicillium sp. (NO. 24).

Penicitroamide (1), a new metabolite with a new framework, was isolated from the ethyl acetate extract of the PDB (Potato Dextrose Broth) medium of Penicillium sp. (NO. 24). The endophytic fungus Penicillium sp. (NO. 24) was obtained from the healthy leaves of Tapiscia sinensis Oliv. The structure of penicitroamide (1) features a bicyclo[3.2.1]octane core unit with a high degree of carbonylization (four carbonyl groups and one enol group). The chemical structure of penicitroamide (1) was elucidated by analysis of 1D-, 2D-NMR and MS data. In bioassays, penicitroamide (1) displayed antibacterial potency against two plant pathogens, Erwinia carotovora subsp. Carotovora (Jones) Bersey, et al. and Sclerotium rolfsii Sacc. with MIC50 at 45 and 50 µg/mL. Compound 1 also showed 60% lethality against brine shrimp at 10 µg/mL. Penicitroamide (1) exhibited no significant activity against A549, Caski, HepG2 and MCF-7 cells with IC50 > 50 µg/mL. Finally, the possible biosynthetic pathway of penicitroamide (1) was discussed.

Exosomes from adriamycin-resistant breast cancer cells transmit drug resistance partly by delivering miR-222.

Breast cancer (BCa) is one of the major deadly cancers in women. However, treatment of BCa is still hindered by the acquired-drug resistance. It is increasingly reported that exosomes take part in the development, metastasis, and drug resistance of BCa. However, the specific role of exosomes in drug resistance of BCa is poorly understood. In this study, we investigate whether exosomes transmit drug resistance through delivering miR-222. We established an adriamycin-resistant variant of Michigan Cancer Foundation-7 (MCF-7) breast cancer cell line (MCF-7/Adr) from a drug-sensitive variant (MCF-7/S). Exosomes were isolated from cell supernatant by ultracentrifugation. Cell viability was assessed by MTT assay and apoptosis assay. Individual miR-222 molecules in BCa cells were detected by fluorescence in situ hybridization (FISH). Then, FISH was combined with locked nucleic acid probes and enzyme-labeled fluorescence (LNA-ELF-FISH). Individual miR-222 could be detected as bright photostable fluorescent spots and then the quantity of miR-222 per cell could be counted. Stained exosomes were taken in by the receipt cells. MCF-7/S acquired drug resistance after co-culture with exosomes from MCF-7/Adr (A/exo) but did not after co-culture with exosomes from MCF-7/S (S/exo). The quantity of miR-222 in A/exo-treated MCF-7/S was significantly greater than in S/exo-treated MCF-7/S. MCF-7/S transfected with miR-222 mimics acquired adriamycin resistance while MCF-7/S transfected with miR-222 inhibitors lost resistance. In conclusion, exosomes are effective in transmitting drug resistance and the delivery of miR-222 via exosomes may be a mechanism.

Exosomes in development, metastasis and drug resistance of breast cancer.

Transport through the cell membrane can be divided into active, passive and vesicular types (exosomes). Exosomes are nano-sized vesicles released by a variety of cells. Emerging evidence shows that exosomes play a critical role in cancers. Exosomes mediate communication between stroma and cancer cells through the transfer of nucleic acid and proteins. It is demonstrated that the contents and the quantity of exosomes will change after occurrence of cancers. Over the last decade, growing attention has been paid to the role of exosomes in the development of breast cancer, the most life-threatening cancer in women. Breast cancer could induce salivary glands to secret specific exosomes, which could be used as biomarkers in the diagnosis of early breast cancer. Exosome-delivered nucleic acid and proteins partly facilitate the tumorigenesis, metastasis and resistance of breast cancer. Exosomes could also transmit anti-cancer drugs outside breast cancer cells, therefore leading to drug resistance. However, exosomes are effective tools for transportation of anti-cancer drugs with lower immunogenicity and toxicity. This is a promising way to establish a drug delivery system.

Role of miR-155 in drug resistance of breast cancer.

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expressions at posttranscriptional level. Growing evidence points to their significant role in the acquisition of drug resistance in cancers. Studies show that miRNAs are often aberrantly expressed in human cancer cells which are associated with tumorigenesis, metastasis, invasiveness, and drug resistance. Breast cancer is the leading cause of cancer-induced death in women. Over the last decades, increasing attention has been paid to the effects of miRNAs on the development of breast cancer drug resistance. Among them, miR-155 takes part in a sequence of bioprocesses that contribute to the development of such drug resistance, including repression of FOXO3a, enhancement of epithelial-to-mesenchymal transition (EMT) and mitogen-activated protein kinase (MAPK) signaling, reduction of RhoA, and affecting the length of telomeres. In this review, we discuss the role of miR-155 in the acquisition of breast cancer drug resistance. This will provide a new way in antiresistance treatment of drug-resistant breast cancer.

Exosomes mediate drug resistance transfer in MCF-7 breast cancer cells and a probable mechanism is delivery of P-glycoprotein.

Acquired drug resistance is a major obstacle to chemotherapy of cancers. In this study, we aim to investigate the role of exosomes in drug-resistance transfer between breast cancer cells and detect the probable mechanism. A docetaxel-resistant variant of MCF-7 cell line (MCF-7/DOC) was established and then compared with the drug-sensitive variant (MCF-7/S). Exosomes were expelled from the cell supernatant using ultracentrifugation. Drug resistance was assessed by apoptosis assay and MTT examination. Expressions of P-glycoprotein (P-gp) were analyzed by flow cytometry. Stained exosomes were absorbed by receipt cells. MCF-7/S in the presence of exosomes extracted from the supernatant of MCF-7/DOC (DOC/exo) acquired drug resistance, while MCF-7/S exposed to their own exosomes (S/exo) did not. P-gp expression patterns of exosomes were similar as the originated cells. P-gp expression of MCF-7/S increased after incubation with DOC/exo and was affected by the amount of exosomes. Exosomes are effective in transferring drug resistance as well as P-gp from drug-resistant breast cancer cells to sensitive ones. The delivery of P-gp via exosomes may be a mechanism of exosome-mediated drug resistance transfer.

Down-regulation of miRNA-452 is associated with adriamycin-resistance in breast cancer cells.

Adriamycin (ADR) is an important chemotherapeutic agent frequently used in treatment of breast cancer. However, resistance to ADR results in treatment failure in many patients. Recent studies have indicated that microRNAs (miRNAs) may play an important role in such drug-resistance. In the present study, microRNA-452 (miR-452) was found to be significantly down-regulated in adriamycin-resistant MCF-7 cells (MCF-7/ADR) compared with the parental MCF-7 cells by miRNA microarray and real-time quantitative PCR (RT-qPCR). MiR-452 mimics and inhibitors partially changed the adriamycin-resistance of breast cancer cells, as also confirmed by apoptosis assay. In exploring the potential mechanisms of miR-452 in the adriamycin-resistance of breast cancer cells, bioinformatics analysis, RT-qPCR and Western blotting showed that dysregulation of miR-452 played an important role in the acquired adriamycin-resistance of breast cancer, maybe at least in part via targeting insulin-like growth factor-1 receptor (IGF-1R).

Exosomes from docetaxel-resistant breast cancer cells alter chemosensitivity by delivering microRNAs.

Breast cancer (BCa) remains chemo-unresponsive by inevitable progression of resistance to first-line treatment with docetaxel (doc). Emerging studies indicate that exosomes act as mediators of intercellular communication between heterogeneous populations of tumor cells, engendering a transmitted drug resistance for cancer development. Such modulatory effects have been related to the constant shuttle of biologically active molecules including microRNAs (miRNAs). Here, we aimed to investigate the relevance of exosome-mediated miRNA delivery in resistance transmission of BCa subpopulations. Using microarray and polymerase chain reaction, we found that exosomes from doc-resistant BCa cells (D/exo) loaded cellular miRNAs. Following D/exo transfer to the fluorescent sensitive cells (GFP-S), some miRNAs were significantly increased in recipient GFP-S. Target gene prediction and pathway analysis revealed the involvement of the top 20 most abundant miRNAs of D/exo in pathways implicated in therapy failure. Coculture assays showed that miRNA-containing D/exo increased the overall resistance of GFP-S to doc exposure. Moreover, D/exo was able to alter gene expression in GFP-S. Our results open up an intriguing possibility that drug-resistant BCa cells may spread chemoresistance to sensitive ones by releasing exosomes and that the effects could be partly attributed to the intercellular transfer of specific miRNAs.

Exosomes from drug-resistant breast cancer cells transmit chemoresistance by a horizontal transfer of microRNAs.

Adriamycin and docetaxel are two agents commonly used in treatment of breast cancer, but their efficacy is often limited by the emergence of chemoresistance. Recent studies indicate that exosomes act as vehicles for exchange of genetic cargo between heterogeneous populations of tumor cells, engendering a transmitted drug resistance for cancer development and progression. However, the specific contribution of breast cancer-derived exosomes is poorly understood. Here we reinforced other's report that human breast cancer cell line MCF-7/S could acquire increased survival potential from its resistant variants MCF-7/Adr and MCF-7/Doc. Additionally, exosomes of the latter, A/exo and D/exo, significantly modulated the cell cycle distribution and drug-induced apoptosis with respect to S/exo. Exosomes pre-treated with RNase were unable to regulate cell cycle and apoptosis resistance, suggesting an RNA-dependent manner. Microarray and polymerase chain reaction for the miRNA expression profiles of A/exo, D/exo, and S/exo demonstrated that they loaded selective miRNA patterns. Following A/exo and D/exo transfer to recipient MCF-7/S, the same miRNAs were significantly increased in acquired cells. Target gene prediction and pathway analysis showed the involvement of miR-100, miR-222, and miR-30a in pathways implicated in cancer pathogenesis, membrane vesiculation and therapy failure. Furthermore, D/exo co-culture assays and miRNA mimics transfection experiments indicated that miR-222-rich D/exo could alter target gene expression in MCF-7/S. Our results suggest that drug-resistant breast cancer cells may spread resistance capacity to sensitive ones by releasing exosomes and that such effects could be partly attributed to the intercellular transfer of specific miRNAs.

MicroRNA-452 contributes to the docetaxel resistance of breast cancer cells.

MicroRNA-452 (miRNA-452) was overexpressed in docetaxel-resistant human breast cancer MCF-7 cells (MCF-7/DOC). However, its role in modulating the sensitivity of breast cancer cells to docetaxel (DOC) remains unclear. The aim of this study is to investigate the role of miRNA-452 in the sensitivity of breast cancer cells to DOC.Real-time quantitative PCR (RT-qPCR) were used to identify the differential expression of miRNA-452 between MCF-7/DOC and MCF-7 cells. MiRNA-452 mimic was transfected into MCF-7 cells and miRNA-452 inhibitor was transfected into MCF-7/DOC cells. The role of miRNA-452 in these transfected cells was evaluated using RT-qPCR, MTT assay, and flow cytometry assay. The relationship of miRNA-452 and its predictive target gene "anaphase-promoting complex 4" (APC4) was analyzed by RT-qPCR and Western blot.MiRNA-452 showed significantly higher expression (78.9-folds) in MCF-7/DOC cells compared to parental MCF-7 cells. The expression of miRNA-452 in the mimic transfected MCF-7 cells was upregulated 212.2-folds (P < 0.05) compared to its negative control (NC), and the half maximal inhibitory concentration (IC50) value of DOC (1.98 ± 0.15 µM) was significantly higher than that in its NC (0.85 ± 0.08 µM, P < 0.05) or blank control (1.01 ± 0.19 µM, P < 0.05). Furthermore, its apoptotic rate (6.3 ± 1.3 %) was distinctly decreased compared with that in its NC (23.8 ± 6.6 %, P < 0.05) or blank control (18.6 ± 4.7 %, P < 0.05). In contrast, the expression of miRNA-452 in the inhibitor-transfected MCF-7/DOC cells was downregulated 0.58-fold (P < 0.05) compared to its NC, the IC50 value of DOC (44.5 ± 3.2 µM) was significantly lower than that in its NC (107.3 ± 6.63 µM, P < 0.05) or blank control (102.22 ± 11.34 µM, P < 0.05), and the apoptotic rate (45.5 ± 10.8 %) was distinctly increased compared with its NC (9.9 ± 2.2 %, P < 0.05) and blank control (9.4 ± 2.5 %, P < 0.05). Further, there was an inverse association between miRNA-452 and APC4 expression in breast cancer cells in vitro.Dysregulation of miRNA-452 involved in the DOC resistance formation of breast cancer cells may be, in part, via targeting APC4.

MicroRNAs delivered by extracellular vesicles: an emerging resistance mechanism for breast cancer.

Resistance to chemotherapy and endocrine therapy as well as targeted drugs is a major problem in treatment of breast cancer. Over the last decades, emerging studies have revealed that extracellular vesicles, which are chronically released by breast cancer cells and surrounding stromal cells, influence the action of most commonly used therapeutics. Such modulatory effects have been related to the transport of biologically active molecules including proteins and functional microRNAs. In this review, we highlight recent studies regarding extracellular vesicle-mediated microRNA delivery in formatting drug resistance. We also suggest the use of extracellular vesicles as a promising method in antiresistance treatment.