Detection of MicroRNAs Using Synthetic Toehold Switch in Mammalian Cells.

Engineering synthetic gene circuits to control cellular functions has a broad application in the field of synthetic biology. Synthetic RNA-based switches that can operate at the transcriptional and posttranscriptional level have also drawn significant interest for the application of next-generation therapeutics and diagnostics. Thus, RNA-based switchable platforms are needed to report dynamic cellular mechanisms which play an important role in cell development and diseases. Recently, several RNA-based switches have been designed and utilized for biosensing and molecular diagnostics. However, miRNA-based switches have not been well established or characterized, especially for eukaryotic translational control. Here, we designed a novel synthetic toehold switch for detection of exogenously and endogenously expressed miRNAs in CHO, HeLa, HEK 293, and MDA-MB-231 breast cancer cells. Multiplex detection of miR-155 and miR-21 was tested using two toehold switches to evaluate the orthogonality and programmability of this synthetic platform.

Synergistic anti-cancer and attenuation effects of thymosin on chemotherapeutic drug vinorelbine in tumor-bearing zebrafish.

Vinorelbine, the standard chemotherapy drug on advanced lung cancer, causes adverse events such as immunosuppression and bone marrow suppression. Thus, it is necessary to find drugs that could improve immune function and synergistically enhance the anti-tumor effect of vinorelbine. Thymosin is reported to inhibit tumor growth as an immunomodulator. Herein, to study the synergistic anti-cancer and attenuation effects of thymosin on vinorelbine, human lung cancer A549 cells that were labeled with CM-DiI were transplanted into zebrafish to establish the lung cancer xenotransplanted model. After treatment of vinorelbine and different concentrations of thymosin, the fluorescence intensity of CM-DiI-labeled A549 cells and the number of apoptotic muscle cells in the tumor-bearing zebrafish were detected. Besides, effects of thymosin on vinorelbine-reduced macrophages and T cells were identified in the transgenic zebrafish (Tg:zlyz-EGFP and Tg:rag2-DsRed). Then, the qRT-PCR was used to determine the alterations of the immune-related factors at the transcription level. Thymosin showed a marked synergistic anti-cancer effect with vinorelbine for the xenograft human lung cancer A549 cells, and the synergistic effect enhanced in a dose-dependent manner. Moreover, thymosin alleviated vinorelbine-induced muscle cell apoptosis, macrophage reduction, and T cell suppression. Compared with the vinorelbine group, co-administration with thymosin raised the mRNA levels of TNF-α, TNF-ß, INF-γ, and GM-CSF. Thus, thymosin possesses synergistic anti-cancer effect on vinorelbine, and has protective effect on vinorelbine-induced immunosuppression. Thymosin, as an adjuvant immunomodulatory therapy, has great potential in enhancing the clinical application of vinorelbine.

Probing Notch1-Dll4 signaling in regulating osteogenic differentiation of human mesenchymal stem cells using single cell nanobiosensor.

Human mesenchymal stem cells (hMSCs) have great potential in cell-based therapies for tissue engineering and regenerative medicine due to their self-renewal and multipotent properties. Recent studies indicate that Notch1-Dll4 signaling is an important pathway in regulating osteogenic differentiation of hMSCs. However, the fundamental mechanisms that govern osteogenic differentiation are poorly understood due to a lack of effective tools to detect gene expression at single cell level. Here, we established a double-stranded locked nucleic acid (LNA)/DNA (LNA/DNA) nanobiosensor for gene expression analysis in single hMSC in both 2D and 3D microenvironments. We first characterized this LNA/DNA nanobiosensor and demonstrated the Dll4 mRNA expression dynamics in hMSCs during osteogenic differentiation. By incorporating this nanobiosensor with live hMSCs imaging during osteogenic induction, we performed dynamic tracking of hMSCs differentiation and Dll4 mRNA gene expression profiles of individual hMSC during osteogenic induction. Our results showed the dynamic expression profile of Dll4 during osteogenesis, indicating the heterogeneity of hMSCs during this dynamic process. We further investigated the role of Notch1-Dll4 signaling in regulating hMSCs during osteogenic differentiation. Pharmacological perturbation is applied to disrupt Notch1-Dll4 signaling to investigate the molecular mechanisms that govern osteogenic differentiation. In addition, the effects of Notch1-Dll4 signaling on hMSCs spheroids differentiation were also investigated. Our results provide convincing evidence supporting that Notch1-Dll4 signaling is involved in regulating hMSCs osteogenic differentiation. Specifically, Notch1-Dll4 signaling is active during osteogenic differentiation. Our results also showed that Dll4 is a molecular signature of differentiated hMSCs during osteogenic induction. Notch inhibition mediated osteogenic differentiation with reduced Alkaline Phosphatase (ALP) activity. Lastly, we elucidated the role of Notch1-Dll4 signaling during osteogenic differentiation in a 3D spheroid model. Our results showed that Notch1-Dll4 signaling is required and activated during osteogenic differentiation in hMSCs spheroids. Inhibition of Notch1-Dll4 signaling mediated osteogenic differentiation and enhanced hMSCs proliferation, with increased spheroid sizes. Taken together, the capability of LNA/DNA nanobiosensor to probe gene expression dynamics during osteogenesis, combined with the engineered 2D/3D microenvironment, enables us to study in detail the role of Notch1-Dll4 signaling in regulating osteogenesis in 2D and 3D microenvironment. These findings will provide new insights to improve cell-based therapies and organ repair techniques.

A tunable amphiphilic Enteromorpha-modified graphene aerogel for oil/water separation.

Three-dimensional graphene aerogel materials used for treatment of oily wastewater with sophisticated composition remains a challenge due to volume shrinkage, resulting in single-function and low adsorption capacity. In this work, renewable Enteromorpha was introduced into the graphene aerogel via facile hydrothermal-freeze casting treatment, forming the compression, ultralight and amphiphilic adsorbent for oil spill cleanup and water pollution remediation. Meanwhile, further freeze casting avoids aerogel collapse for capillary tension during drying and produce more hierarchical pores. As for oil spill clean up, the Enteromorpha modified graphene aerogel (EGA) exhibits excellent adsorption capacity towards oil and organic solvents than pristine graphene aerogel (GA). Even after several cycles by compression and heat treatment, it still has a stable adsorption capacity for oil and organic solvents. The EGA also showed high ability to absorb water-soluble pollutants, such as dyes through hydrogen bonding and electrostatic reactions between dye molecules and aerogel. The facile strategy to fabricate the Enteromorpha-based amphiphilic EGA broadens the applications in water treatment through the high-value utilization of Enteromorpha.

Tributyltin reduces bone mineral density by reprograming bone marrow mesenchymal stem cells in rat.

Tributyltin (TBT), a proven endocrine disrupter, was widely used in industry and agriculture. Previous research showed that TBT could alter the balance between osteogenesis and adipogenesis, which may have significant consequences for bone health. Herein, we exposed male rats to TBT chloride (TBTCl) to evaluate the deleterious effects of TBT on bone. Exposure to 50 µg kg-1 TBT resulted in a significant decrease in bone mineral density (BMD) at the femur diaphysis region in the rat. A dose-dependent increase in lipid accumulation and adipocyte number was observed in the bone marrow (BM) of the femur. Meanwhile, TBTCl treatment significantly enhanced the expression of PPARγ and attenuated the expression of Runx2 and ß-catenin in BM. In addition, serum ALP activity of TBT-exposed rats also showed a dose-dependent decrease. These results suggest that TBT could reduce BMD via inhibition of the Wnt/ß-catenin pathway and skew the adipo-osteogenic balance in the BM of rats.

A Novel Synthetic Toehold Switch for MicroRNA Detection in Mammalian Cells.

MicroRNAs (miRNA or miR) are short noncoding RNA of about 21-23 nucleotides that play critical roles in multiple aspects of biological processes by mediating translational repression through targeting messenger RNA (mRNA). Conventional methods for miRNA detection, including RT-PCR and Northern blot, are limited due to the requirement of cell disruption. Here, we developed a novel synthetic toehold switch, inspired by the toehold switches developed for bacterial systems, to detect endogenous and exogenously expressed miRNAs in mammalian cells, including HEK 293, HeLa, and MDA-MB-231 cells. Transforming growth factor ß-induced miR-155 expression in MDA-MB-231 cells could be detected by the synthetic toehold switch. The experimental results showed the dynamic range of current design of toehold switch is about two. Furthermore, we tested multiplex detection of miR-155 and miR-21 in HEK 293 cells by using miR-155 and miR-21 toehold switches. These toehold switches provide a modest level of orthogonality and could be optimized to achieve a better dynamic range. Our experimental results demonstrate the capability of miRNA toehold switch for detecting and visualizing miRNA expression in mammalian cells, which may potentially lead to new therapeutic or diagnostic applications.

The relation of passive smoking with cervical cancer: A systematic review and meta-analysis.

BACKGROUND: Published studies about passive smoking and cervical cancer have found inconsistent results. Hence, the present meta-analysis was performed to assess this association. METHODS: A systematical search was performed to identify eligible cohort and case-control studies in PubMed, Scopus, Elsevier ScienceDirect, and Web of Science databases (up to March, 2018). The quality of included studies was assessed by the Newcastle-Ottawa quality scale (NOS). The random effects model (REM) was used to calculate the pooled odds ratio (ORs). Subgroup and sensitivity analyses were performed. Publication bias was assessed by funnel plot, using Begg's test and Egger's test. RESULTS: Around 14 eligible studies were included for analysis, which included a total of 384,995 participants. The pooled ORs of passive smoking with cervical cancer risk was 1.70 (95% CI: 1.40-2.07, I = 64.3%). Subgroups stratified by continent, study design, quality score, and cervical cancer types/phases suggested that the result was robust. For instance, the pooled ORs for the cohort and case-control studies was 1.37 (95% CI: 1.16-1.62, I = 0%) and 2.09 (95% CI: 1.52-2.89, I = 76.6%), respectively. The pooled ORs ranged from 1.61 (95%CI: 1.34-1.92) to 1.77 (95%CI: 1.44-2.16) after one study was removed each time in the sensitivity analyses, indicating that the result was stable. Publication bias was detected by funnel plot and Egger's tests. The recalculated ORs were 1.33 (95% CI: 1.21-1.47). CONCLUSIONS: This meta-analysis provides evidence that passive smoking is associated with an increased risk of cervical cancer.

A gapmer aptamer nanobiosensor for real-time monitoring of transcription and translation in single cells.

Transcription and translation are under tight spatiotemporal regulation among cells to coordinate multicellular organization. Methods that allow massively parallel detection of gene expression dynamics at the single cell level are required for elucidating the complex regulatory mechanisms. Here we present a multiplex nanobiosensor for real-time monitoring of protein and mRNA expression dynamics in live cells based on gapmer aptamers and complementary locked nucleic acid probes. Using the multiplex nanobiosensor, we quantified spatiotemporal dynamics of vascular endothelial growth factor A mRNA and protein expressions in single human endothelial cells during microvascular self-organization. Our results revealed distinct gene regulatory processes in the heterogeneous cell subpopulations.

Valproic acid sensitizes breast cancer cells to hydroxyurea through inhibiting RPA2 hyperphosphorylation-mediated DNA repair pathway.

It was reported that valproic acid (VPA, a histone deacetylase inhibitor) can sensitize cancer cells to hydroxyurea (HU, a ribonucleotide reductase inhibitor) for chemotherapy, although the mechanism of VPA-induced HU sensitization is unclear. In this study, we systematically characterized VPA-induced HU sensitization of breast cancer cells. Multiple breast cancer cell models were employed to investigate whether the safe concentration of 0.5mM VPA and 2mM HU can result in DNA double-strand breaks (DSBs) and impact cell survival. Furthermore, the underlying mechanism was explored through cell biology assays, including clonogenic survival, homologous recombination (HR) activity, immunoblot and immunofluorescence. We found that VPA and HU cooperatively suppressed cancer cell survival. VPA resulted in the accumulation of more DNA double-strand breaks (DSBs) in response to HU-induced replication arrest and was able to block HU-stimulated homologous recombination (HR) through inhibiting the activity of two key HR repair proteins by hyperphosphorylation of replication protein A2 (RPA2-p) and recombinase Rad51. However, apoptosis was not detected under this condition. In addition, the results from the survival fraction in the cells expressing defective RPA2-p showed that VPA disrupted the HU-induced RPA2-p-Rad51-mediated HR pathway. Importantly, these findings were further supported by analyzing primary-culture cells from the tissue of chemical carcinogen (DMBA)-induced breast cancer in rats. Thus, our data demonstrated that VPA and HU synergistically suppressed tumor cells via disturbing RPA2-p-mediated DNA repair pathway, which provides a new way for combining chemotherapeutic drugs to sensitize breast cancer cells.

Neuroprotective Effect of Calpeptin on Acrylamide-Induced Neuropathy in Rats.

Acrylamide (ACR) is a vinyl monomer with established human neurotoxic effects, which is characterized by the accumulation of neurofilaments (NFs) in the distal swellings of large axons in peripheral and central nervous systems. However, the mechanisms of neurotoxicity remain unclear. The objective is to investigate the neuroprotective effect of calpeptin (CP) on ACR-induced neuropathy and its mechanism. Female adult Wistar rats were randomly divided into four groups (control, CP, ACR, and ACR + CP group). Control group received 0.9 % saline, ACR and ACR + CP groups received 30 mg/kg ACR by intraperitoneal injection. In addition, CP and ACR + CP groups also received 200 µg/kg CP. Gait analysis and hind limb splay were measured weekly to analyze neurobehavioral changes. The calpain activity and the changes of NFs protein levels in spinal cord are determined. Compared with control group, body weight of rats in ACR group decreased by 11.3 % (P < 0.01), while in ACR + CP group body weight increased significantly by 8.3 % (P < 0.01) compared with ACR group by the end of the 4th week; gait score of rats in both ACR and ACR + CP groups increased significantly by 167 % and 100 % (P < 0.01) compared with control group, while it decreased significantly by 25.1 % (P < 0.01) in ACR + CP group compared with ACR group; the distance of hind limb splay in both ACR and ACR + CP groups increased by 76.7 % and 49.5 % (P < 0.01) compared with control group, while it decreased by 15.4 % (P < 0.01) in ACR + CP group compared with ACR group; calpain activity of spinal cord at ACR and ACR + CP groups increased significantly by 14.9 % and 10.0 % (P < 0.01) compared with control group, while it decreased 4.2 % (P < 0.01) in ACR + CP group compared with ACR group; compared with control group, the levels of light NF (NF-L), medium NF (NF-M) and heavy NF (NF-H) subunits increased by 81.2 %, 263.6 % and 22.6 % (P < 0.01) in the supernatant of ACR group in spinal cord tissue and increased by 28.4 %, 96.6 % and 10.6 % (P < 0.01) in ACR + CP group, while the levels of NF-L, NF-M and NF-H subunits decreased by 29.1 %, 45.9 % and 9.8 % (P < 0.01) in ACR + CP group compared with ACR group. The present results suggested that CP can relieve ACR neuropathy by decrease calpain activity and NFs degradation. The changes of calpain activity and NFs may be one of the mechanisms of ACR-induced neuropathy.

Notch1-Dll4 signalling and mechanical force regulate leader cell formation during collective cell migration.

At the onset of collective cell migration, a subset of cells within an initially homogenous population acquires a distinct 'leader' phenotype with characteristic morphology and motility. However, the factors driving the leader cell formation as well as the mechanisms regulating leader cell density during the migration process remain to be determined. Here we use single-cell gene expression analysis and computational modelling to show that the leader cell identity is dynamically regulated by Dll4 signalling through both Notch1 and cellular stress in a migrating epithelium. Time-lapse microscopy reveals that Dll4 is induced in leader cells after the creation of the cell-free region and leader cells are regulated via Notch1-Dll4 lateral inhibition. Furthermore, mechanical stress inhibits Dll4 expression and leader cell formation in the monolayer. Collectively, our findings suggest that a reduction of mechanical force near the boundary promotes Notch1-Dll4 signalling to dynamically regulate the density of leader cells during collective cell migration.

Oncogenic KRAS confers chemoresistance by upregulating NRF2.

Oncogenic KRAS mutations found in 20% to 30% of all non-small cell lung cancers (NSCLC) are associated with chemoresistance and poor prognosis. Here we demonstrate that activation of the cell protective stress response gene NRF2 by KRAS is responsible for its ability to promote drug resistance. RNAi-mediated silencing of NRF2 was sufficient to reverse resistance to cisplatin elicited by ectopic expression of oncogenic KRAS in NSCLC cells. Mechanistically, KRAS increased NRF2 gene transcription through a TPA response element (TRE) located in a regulatory region in exon 1 of NRF2. In a mouse model of mutant KrasG12D-induced lung cancer, we found that suppressing the NRF2 pathway with the chemical inhibitor brusatol enhanced the antitumor efficacy of cisplatin. Cotreatment reduced tumor burden and improved survival. Our findings illuminate the mechanistic details of KRAS-mediated drug resistance and provide a preclinical rationale to improve the management of lung tumors harboring KRAS mutations with NRF2 pathway inhibitors.

Mapping photothermally induced gene expression in living cells and tissues by nanorod-locked nucleic acid complexes.

The photothermal effect of plasmonic nanostructures has numerous applications, such as cancer therapy, photonic gene circuit, large cargo delivery, and nanostructure-enhanced laser tweezers. The photothermal operation can also induce unwanted physical and biochemical effects, which potentially alter the cell behaviors. However, there is a lack of techniques for characterizing the dynamic cell responses near the site of photothermal operation with high spatiotemporal resolution. In this work, we show that the incorporation of locked nucleic acid probes with gold nanorods allows photothermal manipulation and real-time monitoring of gene expression near the area of irradiation in living cells and animal tissues. The multimodal gold nanorod serves as an endocytic delivery reagent to transport the probes into the cells, a fluorescence quencher and a binding competitor to detect intracellular mRNA, and a plasmonic photothermal transducer to induce cell ablation. We demonstrate the ability of the gold nanorod-locked nucleic acid complex for detecting the spatiotemporal gene expression in viable cells and tissues and inducing photothermal ablation of single cells. Using the gold nanorod-locked nucleic acid complex, we systematically characterize the dynamic cellular heat shock responses near the site of photothermal operation. The gold nanorod-locked nucleic acid complex enables mapping of intracellular gene expressions and analyzes the photothermal effects of nanostructures toward various biomedical applications.

Role of oxidative/nitrative stress in hepatic encephalopathy induced by thioacetamide.

The study was designed to reveal the pathogenic mechanism of peroxynitrite in hepatic encephalopathy (HE), assess oxidative/nitrative stress in relation to HE induced by thiacetamide (TAA) and provide new ideas and scientific basis for the etiology and treatment of HE. Male Wistar rats were divided into four groups randomly: A (control), B (model), C (ebselen) and D (solvent). All the groups were treated with TAA by intraperitoneal (i.p.) except group A (treated with saline i.p.) to manufacture the model of HE. When rats treated with TAA came to the second stage of HE the four groups were administered intragastrically (i.g.) with saline (A, B), ebselen (C) and dimethyl sulfoxide (DMSO) (D), respectively. Plasma was collected to detect the levels of 3-nitrotyrosine (3-NT), NO, T-SOD and MDA. The results showed that the levels of 3-NT, NO, MDA significantly increased and T-SOD decreased obviously in rats suffering from HE. With the development and progression of HE the extent of oxidative/nitrative stress increased. When treated with ebselen the symptoms of HE mitigated and the levels of biochemical indicators ameliorated significantly. This indicates that oxidative/nitrative stress is involved in the mechanisms of hepatic encephalopathy.