Aptamers and their potential to selectively target aspects of EGF, Wnt/β-catenin and TGFβ-smad family signaling

RRM2 Regulates Hepatocellular Carcinoma Progression Through Activation of TGF-β/Smad Signaling and Hepatitis B Virus Transcription

BACKGROUND

Hepatocellular carcinoma (HCC) is a type of malignant tumor with high morbidity and mortality. Untimely treatment and high recurrence are currently the major challenges for HCC. The identification of potential targets of HCC progression is crucial for the development of new therapeutic strategies.

METHODS

Bioinformatics analyses have been employed to discover genes that are differentially expressed in clinical cases of HCC. A variety of pharmacological methods, such as MTT, colony formation, EdU, Western blotting, Q-PCR, wound healing, Transwell, cytoskeleton F-actin filaments, immunohistochemistry (IHC), hematoxylin-eosin (HE) staining, and dual-luciferase reporter assay analyses, were utilized to study the pharmacological effects and potential mechanisms of ribonucleotide reductase regulatory subunit M2 (RRM2) in HCC.

RESULTS

RRM2 expression is significantly elevated in HCC, which is well correlated with poor clinical outcomes. Both in vitro and in vivo experiments demonstrated that RRM2 promoted HCC cell growth and metastasis. Mechanistically, RRM2 modulates the EMT phenotype of HCC, and further studies have shown that RRM2 facilitates the activation of the TGF-β/Smad signaling pathway. SB431542, an inhibitor of TGF-β signaling, significantly inhibited RRM2-induced cell migration. Furthermore, RRM2 expression was correlated with diminished survival in HBV-associated HCC patients. RRM2 knockdown decreased the levels of HBV RNA, pgRNA, cccDNA, and HBV DNA in HepG2.2.15 cells exhibiting sustained HBV infection, while RRM2 knockdown inhibited the activity of the HBV Cp, Xp, and SpI promoters.

CONCLUSION

RRM2 is involved in the progression of HCC by activating the TGF-β/Smad signaling pathway. RRM2 increases HBV transcription in HBV-expressing HCC cells. Targeting RRM2 may be of potential value in the treatment of HCC.

TGF-β signaling in health, disease, and therapeutics

Transforming growth factor (TGF)-β is a multifunctional cytokine expressed by almost every tissue and cell type. The signal transduction of TGF-β can stimulate diverse cellular responses and is particularly critical to embryonic development, wound healing, tissue homeostasis, and immune homeostasis in health. The dysfunction of TGF-β can play key roles in many diseases, and numerous targeted therapies have been developed to rectify its pathogenic activity. In the past decades, a large number of studies on TGF-β signaling have been carried out, covering a broad spectrum of topics in health, disease, and therapeutics. Thus, a comprehensive overview of TGF-β signaling is required for a general picture of the studies in this field. In this review, we retrace the research history of TGF-β and introduce the molecular mechanisms regarding its biosynthesis, activation, and signal transduction. We also provide deep insights into the functions of TGF-β signaling in physiological conditions as well as in pathological processes. TGF-β-targeting therapies which have brought fresh hope to the treatment of relevant diseases are highlighted. Through the summary of previous knowledge and recent updates, this review aims to provide a systematic understanding of TGF-β signaling and to attract more attention and interest to this research area.

Pharmacotherapy of urethral stricture

Urethral stricture is characterized by the chronic formation of fibrous tissue, leading to the narrowing of the urethral lumen. Despite the availability of various endoscopic treatments, the recurrence of urethral strictures remains a common challenge. Postsurgery pharmacotherapy targeting tissue fibrosis is a promising option for reducing recurrence rates. Although drugs cannot replace surgery, they can be used as adjuvant therapies to improve outcomes. In this regard, many drugs have been proposed based on the mechanisms underlying the pathophysiology of urethral stricture. Ongoing studies have obtained substantial progress in treating urethral strictures, highlighting the potential for improved drug effectiveness through appropriate clinical delivery methods. Therefore, this review summarizes the latest researches on the mechanisms related to the pathophysiology of urethral stricture and the drugs to provide a theoretical basis and new insights for the effective use and future advancements in drug therapy for urethral stricture.

Nanoparticle-Based Bioaffinity Assays: From the Research Laboratory to the Market

Advances in the development of new biorecognition elements, nanoparticle-based labels as well as instrumentation have inspired the design of new bioaffinity assays. This review critically discusses the potential of nanoparticles to replace current enzymatic or molecular labels in immunoassays and other bioaffinity assays. Successful implementations of nanoparticles in commercial assays and the need for rapid tests incorporating nanoparticles in different roles such as capture support, signal generation elements, and signal amplification systems are highlighted. The limited number of nanoparticles applied in current commercial assays can be explained by challenges associated with the analysis of real samples (e.g., blood, urine, or nasal swabs) that are difficult to resolve, particularly if the same performance can be achieved more easily by conventional labels. Lateral flow assays that are based on the visual detection of the red-colored line formed by colloidal gold are a notable exception, exemplified by SARS-CoV-2 rapid antigen tests that have moved from initial laboratory testing to widespread market adaption in less than two years.

Recent Advances in Personal Glucose Meter-Based Biosensors for Food Safety Hazard Detection

Food safety has emerged as a significant concern for global public health and sustainable development. The development of analytical tools capable of rapidly, conveniently, and sensitively detecting food safety hazards is imperative. Over the past few decades, personal glucose meters (PGMs), characterized by their rapid response, low cost, and high degree of commercialization, have served as portable signal output devices extensively utilized in the construction of biosensors. This paper provides a comprehensive overview of the mechanism underlying the construction of PGM-based biosensors, which consists of three fundamental components: recognition, signal transduction, and signal output. It also detailedly enumerates available recognition and signal transduction elements, and their modes of integration. Then, a multitude of instances is examined to present the latest advancements in the application of PGMs in food safety detection, including targets such as pathogenic bacteria, mycotoxins, agricultural and veterinary drug residues, heavy metal ions, and illegal additives. Finally, the challenges and prospects of PGM-based biosensors are highlighted, aiming to offer valuable references for the iterative refinement of detection techniques and provide a comprehensive framework and inspiration for further investigations.

DKK1 Ameliorates Myofibroblast Differentiation in Urethral Fibrosis in Vivo and in Vitro by Regulating the Canonical Wnt Pathway

Background: Urethral stricture is a common disorder of the lower urinary tract in men. A complex network of pathways and interactions are involved in the pathogenesis of urethral fibrosis. However, the mechanisms underlying urethral fibrosis remain poorly understood. Objectives: To investigate the critical role of the canonical Wnt pathway in development of urethral fibrosis and explore DKK1, the endogenous inhibitor of Wnt pathway, as a potential target to prevent urethral fibrosis in vitro and in vivo. Methods: Urethral fibrosis tissue derived from patients and rat models were harvested to assess the activation of the canonical Wnt pathway by using western blot, qRT-PCR and immunohistochemistryWe performed histological staining, western blot, qRT-PCR and immunohistochemistry to examine the effects of DKK1 treatment on in vivo rat urethral fibrosis models. In vitro, human urethral fibroblasts (HUFs) were cultured to examine the effects of DKK1 in TGFβ1-induced HUFs by CCK-8 assay, hydroxyproline assay, flow cytometry, cell migration assay, western blot, qRT-PCR and immunofluorescence. Results: The key components of Wnt signaling were upregulated in urethral fibrosis tissue derived from patients and rat models while DKK 1 was downregulated. DKK1 ameliorated TGFβ1-induced urethral fibrosis in rats. TGFβ1 induced myofibroblast differentiation by upregulating collagen I, collagen III, α-SMA, β-catenin and p-GSK-3β, while DKK1 was decreased. DKK1 significantly inhibited cell proliferation, collagen content, cell migration and promoted cell apoptosis in TGFβ1-induced HUFs. DKK1 significantly suppressed myofibroblast differentiation of TGFβ1-induced HUFs by downregulating collagen I, collagen III, α-SMA, β-catenin and p-GSK-3β with a mechanism independent of Smad2/3. Conclusions: Our study demonstrated that canonical Wnt pathway may be an essential mechanism underlying the pathogenesis of urethral fibrosis and explored the potential role of DKK1 participation in the development of urethral fibrosis.

Electrochemical aptasensor detection of electron transfer flavoprotein subunit beta for leptospirosis diagnosis

Electron transfer flavoprotein subunit beta (ETFB) of Leptospira interrogans is a biomarker for diagnosing leptospiral infection. Thus, the ETFB-specific nuclease-resistant RNA aptamer ETFB3-63 was developed and used in an electrochemical aptasensor to assay ETFB. Although the majority of reported biosensors detect various genes and antibodies of L. interrogans, this is the first attempt to construct an electrochemical biosensor to detect ETFB protein for the diagnosis of leptospiral infection. The ETFB protein can be detected without any extraction phase. In this assay, a single-stranded DNA probe complementary to the ETFB3-63 sequence was immobilized on a screen-printed carbon electrode (SPCE). The aptamer was then incubated and hybridized with the antisense probe on the SPCE. In the presence of ETFB, the aptamer dissociates from the aptamer/probe complex on the SPCE to bind with the protein. Methylene blue was then added to intercalate with the remaining hybridized aptamers, and its signal was measured using differential pulse voltammetry. The signal arising from the intercalated methylene blue decreased with increasing concentration of ETFB, showing a linear response in the range of 50-500 nM of ETFB and 10 to 109 leptospira cells per mL, respectively. The aptasensor signal was also specific to L. interrogans but not to 12 related bacteria tested. In addition, the aptasensor showed similar performance in detecting ETFB spiked in human serum to that in buffer, indicating that proteins in the serum do not interfere with the assay. Therefore, this assay has great potential to develop into a point-of-care electrochemical device that is accurate, cost-effective, and user-friendly for leptospirosis diagnosis.

Sources, Selection, and Microenvironmental Preconditioning of Cells for Urethral Tissue Engineering

Urethral stricture is a common urinary tract disorder in men that can be caused by iatrogenic causes, trauma, inflammation, or infection and often requires reconstructive surgery. The current therapeutic approach for complex urethral strictures usually involves reconstruction with autologous tissue from the oral mucosa. With the goal of overcoming the lack of sufficient autologous tissue and donor site morbidity, research over the past two decades has focused on cell-based tissue-engineered substitutes. While the main focus has been on autologous cells from the penile tissue, bladder, and oral cavity, stem cells from sources such as adipose tissue and urine are competing candidates for future urethral regeneration due to their ease of collection, high proliferative capacity, maturation potential, and paracrine function. This review addresses the sources, advantages, and limitations of cells for tissue engineering in the urethra and discusses recent approaches to improve cell survival, growth, and differentiation by mimicking the mechanical and biophysical properties of the extracellular environment.

TGF-β-induced fibrosis: A review on the underlying mechanism and potential therapeutic strategies

Transforming growth factor-beta (TGF-β) plays multiple homeostatic roles in the regulation of inflammation, proliferation, differentiation and would healing of various tissues. Many studies have demonstrated that TGF-β stimulates activation and proliferation of fibroblasts, which result in extracellular matrix deposition. Its increased expression can result in many fibrotic diseases, and the level of expression is often correlated with disease severity. On this basis, inhibition of TGF-β and its activity has great therapeutic potential for the treatment of various fibrotic diseases such as pulmonary fibrosis, renal fibrosis, systemic sclerosis and etc. By understanding the molecular mechanism of TGF-β signaling and activity, researchers were able to develop different strategies in order to modulate the activity of TGF-β. Antisense oligonucleotide was developed to target the mRNA of TGF-β to inhibit its expression. There are also neutralizing monoclonal antibodies that can target the TGF-β ligands or αvβ6 integrin to prevent binding to receptor or activation of latent TGF-β respectively. Soluble TGF-β receptors act as ligand traps that competitively bind to the TGF-β ligands. Many small molecule inhibitors have been developed to inhibit the TGF-β receptor at its cytoplasmic domain and also intracellular signaling molecules. Peptide aptamer technology has been used to target downstream TGF-β signaling. Here, we summarize the underlying mechanism of TGF-β-induced fibrosis and also review various strategies of inhibiting TGF-β in both preclinical and clinical studies.

Integrated Bioinformatics Analysis Reveals Marker Genes and Potential Therapeutic Targets for Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare cardiovascular disease with very high mortality rate. The currently available therapeutic strategies, which improve symptoms, cannot fundamentally reverse the condition. Thus, new therapeutic strategies need to be established. Our research analyzed three microarray datasets of lung tissues from human PAH samples retrieved from the Gene Expression Omnibus (GEO) database. We combined two datasets for subsequent analyses, with the batch effects removed. In the merged dataset, 542 DEGs were identified and the key module relevant to PAH was selected using WGCNA. GO and KEGG analyses of DEGs and the key module indicated that the pre-ribosome, ribosome biogenesis, centriole, ATPase activity, helicase activity, hypertrophic cardiomyopathy, melanoma, and dilated cardiomyopathy pathways are involved in PAH. With the filtering standard (|MM| > 0.95 and |GS| > 0.90), 70 hub genes were identified. Subsequently, five candidate marker genes (CDC5L, AP3B1, ZFYVE16, DDX46, and PHAX) in the key module were found through overlapping with the top thirty genes calculated by two different methods in CytoHubb. Two of them (CDC5L and DDX46) were found to be significantly upregulated both in the merged dataset and the validating dataset in PAH patients. Meanwhile, expression of the selected genes in lung from PAH chicken measured by qRT-PCR and the ROC curve analyses further verified the potential marker genes' predictive value for PAH. In conclusion, CDC5L and DDX46 may be marker genes and potential therapeutic targets for PAH.

The Smad Dependent TGF-β and BMP Signaling Pathway in Bone Remodeling and Therapies

Bone remodeling is a continuous process that maintains the homeostasis of the skeletal system, and it depends on the homeostasis between bone-forming osteoblasts and bone-absorbing osteoclasts. A large number of studies have confirmed that the Smad signaling pathway is essential for the regulation of osteoblastic and osteoclastic differentiation during skeletal development, bone formation and bone homeostasis, suggesting a close relationship between Smad signaling and bone remodeling. It is known that Smads proteins are pivotal intracellular effectors for the members of the transforming growth factor-β (TGF-β) and bone morphogenetic proteins (BMP), acting as transcription factors. Smad mediates the signal transduction in TGF-β and BMP signaling pathway that affects both osteoblast and osteoclast functions, and therefore plays a critical role in the regulation of bone remodeling. Increasing studies have demonstrated that a number of Smad signaling regulators have potential functions in bone remodeling. Therefore, targeting Smad dependent TGF-β and BMP signaling pathway might be a novel and promising therapeutic strategy against osteoporosis. This article aims to review recent advances in this field, summarizing the influence of Smad on osteoblast and osteoclast function, together with Smad signaling regulators in bone remodeling. This will facilitate the understanding of Smad signaling pathway in bone biology and shed new light on the modulation and potential treatment for osteoporosis.

Interleukin-10 restores glutamate receptor-mediated Ca2+-signaling in brain circuits under loss of Sip1 transcription factor

OBJECTIVE

This study aimed to investigate the connection between the mutation of the Sip1 transcription factor and impaired Ca²⁺-signaling, which reflects changes in neurotransmission in the cerebral cortex in vitro.

METHODS

We used mixed neuroglial cortical cell cultures derived from Sip1 mutant mice. The cells were loaded with a fluorescent ratiometric calcium-sensitive probe Fura-2 AM and epileptiform activity was modeled by excluding magnesium ions from the external media or adding a GABA(A) receptor antagonist, bicuculline. Intracellular calcium dynamics were recorded using fluorescence microscopy. To identify the level of gene expression, the Real-Time PCR method was used.

RESULTS

It was found that cortical neurons isolated from homozygous (Sip1^fl/fl) mice with the Sip1 mutation demonstrate suppressed Ca²⁺ signals in models of epileptiform activity in vitro. Wild-type cortical neurons are characterized by synchronous high-frequency and high-amplitude Ca²⁺ oscillations occurring in all neurons of the network in response to Mg²⁺-free medium and bicuculline. But cortical Sip1^fl/fl neurons only single Ca²⁺ pulses or attenuated Ca²⁺ oscillations are recorded and only in single neurons, while most of the cell network does not respond to these stimuli. This signal deficiency of Sip1^fl/fl neurons correlates with a suppressed expression level of the genes encoding the subunits of NMDA, AMPA, and KA receptors; protein kinases PKA, JNK, CaMKII; and also the transcription factor Hif1α. These negative effects were partially abolished when Sip1^fl/fl neurons are grown in media with anti-inflammatory cytokine IL-10. IL-10 increases the expression of the above-mentioned genes but not to the level of expression in wild-type. At the same time, the amplitudes of Ca²⁺ signals increase in response to the selective agonists of NMDA, AMPA and KA receptors, and the proportion of neurons responding with Ca²⁺ oscillations to a Mg²⁺-free medium and bicuculline increases.

CONCLUSION

IL-10 restores neurotransmission in neuronal networks with the Sip1 mutation by regulating the expression of genes encoding signaling proteins.

Regenerative and engineered options for urethroplasty

Surgical correction of urethral strictures by substitution urethroplasty - the use of grafts or flaps to correct the urethral narrowing - remains one of the most challenging procedures in urology and is frequently associated with complications, restenosis and poor quality of life for the affected individual. Tissue engineering using different cell types and tissue scaffolds offers a promising alternative for tissue repair and replacement. The past 30 years of tissue engineering has resulted in the development of several therapies that are now in use in the clinic, especially in treating cutaneous, bone and cartilage defects. Advances in tissue engineering for urethral replacement have resulted in several clinical applications that have shown promise but have not yet become the standard of care.

miRNA‑15a‑5p facilitates the bone marrow stem cell apoptosis of femoral head necrosis through the Wnt/β‑catenin/PPARγ signaling pathway

Bone marrow stem cells (BMSCs) are a group cells that function as an underlying cell source for bone tissue regeneration. However, the molecular mechanisms of how BMSCs are induced into apoptosis remains unclear. In the present study, it was demonstrated that the molecular mechanisms of BMSCs were exerted via microRNA-15a-5p (miR-15a-5p) in femoral head necrosis (FHN). Briefly, miRNA-15a-5p expression was elevated in a rat model of FHN. Overexpression of miR-15a-5p promoted the apoptosis of BMSCs and reduced cell growth through the Wnt/β-catenin/peroxisome proliferator-activated receptor γ (PPARγ) signaling pathway. Downregulation of miR-15a-5p reduced the apoptosis of BMSCs and promoted cell growth through the Wnt/β-catenin/PPARγ signaling pathway. The activation of Wnt attenuated the effects of miR-15a-5p on the apoptosis of BMSCs via the β-catenin/PPARγ signaling pathway. In conclusion, the present results indicated that miRNA-15a-5p was involved in the regulation of the apoptosis of BMSCs through regulating the Wnt/β-catenin/PPARγ signaling pathway, which may serve an important role in the regulation of FHN.

Role of Zeb2/Sip1 in neuronal development

Zeb2 (Sip1, Zfhx1b) is a transcription factor that plays essential role in neuronal development. Sip1 mutation in humans was shown to cause Mowat-Wilson syndrome, a syndromic form of Hirschprung's disease. Affected individuals exhibit multiple severe neurodevelopmental defects. Zeb2 can act as both transcriptional repressor and activator. It controls expression of a wide number of genes that regulate various aspects of neuronal development. This review addresses the molecular pathways acting downstream of Zeb2 that cause brain development disorders.

Resveratrol improves prostate fibrosis during progression of urinary dysfunction in chronic prostatitis by mast cell suppression

Voiding dysfunction is the primary clinical manifestation of chronic prostatitis (CP), which is a common urological disease. The present study investigated whether prostate fibrosis was associated with urinary dysfunction in CP and if resveratrol improved urinary dysfunction, and the underlying molecular mechanism. A rat model of CP was established via subcutaneous injections of the pertussis-diphtheria-tetanus vaccine, which was followed by treatment with resveratrol. Bladder pressure and volume tests were performed to investigate the effect of resveratrol on urinary dysfunction in CP rats. Western blotting and immunohistochemical staining examined the expression levels of tryptase, chymase, transforming growth factor (TGF)-β, Wnt and α-smooth muscle actin (α-SMA). The results demonstrated that the maximum capacity of the bladder, residual urine volume and maximum voiding pressure were increased significantly in the CP group compared with the control group. Mast cell (MC) activation, the activity of TGF-β/Wnt/β-catenin pathways, and the expression levels of tryptase and α-SMA in the CP group were increased significantly compared with the control group. Resveratrol treatment significantly reversed these factors. Therefore, the results indicate that MC infiltration may induce prostate fibrosis, which exhibits a close association with urinary dysfunction in CP. Resveratrol may improve fibrosis via the suppression of MC activation and TGF-β/Wnt/β-catenin pathway activities.

The GRHL2/ZEB Feedback Loop-A Key Axis in the Regulation of EMT in Breast Cancer

More than 90% of cancer-related deaths are caused by metastasis. Epithelial-to-Mesenchymal Transition (EMT) causes tumor cell dissemination while the reverse process, Mesenchymal-to-Epithelial Transition (MET) allows cancer cells to grow and establish a potentially deadly metastatic lesion. Recent evidence indicates that in addition to E and M, cells can adopt a stable hybrid Epithelial/Mesenchymal (E/M) state where they can move collectively leading to clusters of Circulating Tumor Cells-the "bad actors" of metastasis. EMT is postulated to occur in all four major histological breast cancer subtypes. Here, we identify a set of genes strongly correlated with CDH1 in 877 cancer cell lines, and differentially expressed genes in cell lines overexpressing ZEB1, SNAIL, and TWIST. GRHL2 and ESRP1 appear in both these sets and also correlate with CDH1 at the protein level in 40 breast cancer specimens. Next, we find that GRHL2 and CD24 expression coincide with an epithelial character in human mammary epithelial cells. Further, we show that high GRHL2 expression is highly correlated with worse relapse-free survival in all four subtypes of breast cancer. Finally, we integrate CD24, GRHL2, and ESRP1 into a mathematical model of EMT regulation to validate the role of these players in EMT. Our data analysis and modeling results highlight the relationships among multiple crucial EMT/MET drivers including ZEB1, GRHL2, CD24, and ESRP1, particularly in basal-like breast cancers, which are most similar to triple-negative breast cancer (TNBC) and are considered the most dangerous subtype. J. Cell. Biochem. 118: 2559-2570, 2017. © 2017 Wiley Periodicals, Inc.

The inhibition of microRNA-15a suppresses hepatitis B virus-associated liver cancer cell growth through the Smad/TGF-β pathway

In the present study, the role of microRNA‑15a (miR‑15a) was investigated in hepatitis B virus (HBV)‑associated liver cancer. The results revealed that the expression levels of miR-15a were increased in HBV-associated liver cancer tissues compared with the levels in normal tumor‑adjacent tissues. Moreover, Smad-7 protein expression in patients with HBV-associated liver cancer was higher than that in normal tumor-adjacent tissues. In addition, miR-15a expression and Smad-7 protein expression were increased in HepG2 hepatocellular carcinoma cells compared with that noted in L-02 normal hepatocytes. In HepG2 cells, miR-15a inhibition suppressed cell proliferation and increased Smad-7 protein expression. The inhibition of miR-15a was also demonstrated to decrease transforming growth factor (TGF)-β1 protein expression and Smad-2, p-Smad-2 and Smad-4 expression levels in HepG2 cells. Furthermore, FSP1 protein expression and caspase-3/-7 activities were enhanced by miR-15a inhibition in HepG2 cells compared with the control group. Treatment with recombinant TGF-β1 was demonstrated to activate Smad‑2/-4 and FSP1 protein expression and increase caspase-3/-7 activity in HepG2 cells. Collectively, these findings demonstrate that the miR-15a/Smad-7/TGF-β pathway is important in HBV-associated liver cancer.

Aptamer-based 'point-of-care testing'

Aptamers are single-stranded oligonucleotides that can be artificially generated by a method called Systematic evolution of ligands by exponential enrichment (SELEX). The generated aptamers have been assessed for high-performance sensing applications due to their appealing characteristics. With either aptamers alone or complementing with antibodies, several high sensitive and portable sensors have been demonstrated for use in 'point-of-care testing'. Due to their high suitability and flexibility, aptamers are conjugated with nanostructures and utilized in field applications. Moreover, aptamers are more amenable to chemical modifications, making them capable of utilization with most developed sensors. In this overview, we discuss novel, portable, and aptamer-based sensing strategies that are suitable for 'point-of-care testing'.

Application of Wnt Pathway Inhibitor Delivering Scaffold for Inhibiting Fibrosis in Urethra Strictures: In Vitro and in Vivo Study

Objective: To evaluate the mechanical property and biocompatibility of the Wnt pathway inhibitor (ICG-001) delivering collagen/poly(l-lactide-co-caprolactone) (P(LLA-CL)) scaffold for urethroplasty, and also the feasibility of inhibiting the extracellular matrix (ECM) expression in vitro and in vivo. Methods: ICG-001 (1 mg (2 mM)) was loaded into a (P(LLA-CL)) scaffold with the co-axial electrospinning technique. The characteristics of the mechanical property and drug release fashion of scaffolds were tested with a mechanical testing machine (Instron) and high-performance liquid chromatography (HPLC). Rabbit bladder epithelial cells and the dermal fibroblasts were isolated by enzymatic digestion method. (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay) and scanning electron microscopy (SEM) were used to evaluate the viability and proliferation of the cells on the scaffolds. Fibrolasts treated with TGF-β1 and ICG-001 released medium from scaffolds were used to evaluate the anti-fibrosis effect through immunofluorescence, real time PCR and western blot. Urethrography and histology were used to evaluate the efficacy of urethral implantation. Results: The scaffold delivering ICG-001 was fabricated, the fiber diameter and mechanical strength of scaffolds with inhibitor were comparable with the non-drug scaffold. The SEM and MTT assay showed no toxic effect of ICG-001 to the proliferation of epithelial cells on the collagen/P(LLA-CL) scaffold with ICG-001. After treatment with culture medium released from the drug-delivering scaffold, the expression of Collagen type 1, 3 and fibronectin of fibroblasts could be inhibited significantly at the mRNA and protein levels. In the results of urethrography, urethral strictures and fistulas were found in the rabbits treated with non-ICG-001 delivering scaffolds, but all the rabbits treated with ICG-001-delivering scaffolds showed wide caliber in urethras. Histology results showed less collagen but more smooth muscle and thicker epithelium in urethras repaired with ICG-001 delivering scaffolds. Conclusion: After loading with the Wnt signal pathway inhibitor ICG-001, the Collagen/P(LLA-CL) scaffold could facilitate a decrease in the ECM deposition of fibroblasts. The ICG-001 delivering Collagen/P(LLA-CL) nanofibrous scaffold seeded with epithelial cells has the potential to be a promising substitute material for urethroplasty. Longer follow-up study in larger animals is needed in the future.

Wnt/β-catenin signaling in bone marrow niche

The bone marrow (BM) niche is a specific physiological environment for hematopoietic and non-hematopoietic stem cells (HSCs). Several signaling pathways (including Wnt/β-catenin) regulate various aspects of stem cell growth, function and death in the BM niche. In addition, the canonical Wnt pathway is crucial for directing self-renewal and differentiation as important mechanisms in many types of stem cells. We review the role of the Wnt/β-catenin pathway in the BM niche and its importance in stem cells. Relevant literature was identified by a PubMed search (1997-2014) of English-language literature by using the following keywords: BM niche, Wnt/β-catenin signaling, osteoblast, osteoclast and bone disease. The Wnt/β-catenin pathway regulates the stability of the β-catenin proto-oncogene. The stabilized β-catenin then translocates to the nucleus, forming a β-catenin-TCF/LEF complex regulating the transcription of specific target genes. Stem cells require β-catenin to mediate their response to Wnt signaling for maintenance and transition from the pluripotent state during embryogenesis. In adult stem cells, Wnt signaling functions at various hierarchical levels to contribute to the specification of the diverse tissues. Aberrant Wnt/β-catenin signaling and its downstream transcriptional regulators are observed in several malignant stem cells and human cancers. Because Wnt signaling can maintain stem cells and cancer cells, the ability to modulate the Wnt pathway either positively or negatively may be of therapeutic relevance. The controlled activation of Wnt signaling might allow us to enhance stem and progenitor cell activity when regeneration is needed.

Progress and Challenges in Developing Aptamer-Functionalized Targeted Drug Delivery Systems

Aptamers, which can be screened via systematic evolution of ligands by exponential enrichment (SELEX), are superior ligands for molecular recognition due to their high selectivity and affinity. The interest in the use of aptamers as ligands for targeted drug delivery has been increasing due to their unique advantages. Based on their different compositions and preparation methods, aptamer-functionalized targeted drug delivery systems can be divided into two main categories: aptamer-small molecule conjugated systems and aptamer-nanomaterial conjugated systems. In this review, we not only summarize recent progress in aptamer selection and the application of aptamers in these targeted drug delivery systems but also discuss the advantages, challenges and new perspectives associated with these delivery systems.

In silico identification of potential therapeutic targets in the TGF-β signal transduction pathway

The transforming growth factor-β (TGF-β) superfamily of cytokines controls fundamental cellular processes, such as proliferation, motility, differentiation, and apoptosis. This fundamental role is emphasized by the widespread presence of mutations of the core components of the TGF-β signal transduction pathway in a number of human diseases. Therefore, there is an increasing interest in the development of therapies to specifically target this pathway. Here we develop a computational approach to identify potential intervention points that are capable of restoring the normal signaling dynamics to the mutated system while maintaining the behavior of normal cells substantially unperturbed. We apply this approach explicitly to the TGF-β pathway to study the signaling dynamics of mutated and normal cells treated with inhibitory drugs and identify the processes in the pathway that are most susceptible to therapeutic intervention.

Editorial of the special issue: signaling molecules and signal transduction in cells

In the special issue “Signaling Molecules and Signal Transduction in Cells” authors were invited to submit papers regarding important and novel aspects of extra- and intracellular signaling which have implications on physiological and pathophysiological processes. These aspects included compounds which are involved in these processes, elucidation of signaling pathways, as well as novel techniques for the analysis of signaling pathways. In response, various novel and important topics are elucidated in this special issue.

Epithelial-mesenchymal transition and its role in the pathogenesis of colorectal cancer

Epithelial-to-mesenchymal transition (EMT) is a collection of events that allows the conversion of adherent epithelial cells, tightly bound to each other within an organized tissue, into independent fibroblastic cells possessing migratory properties and the ability to invade the extracellular matrix. EMT contributes to the complex architecture of the embryo by permitting the progression of embryogenesis from a simple single-cell layer epithelium to a complex three-dimensional organism composed of both epithelial and mesenchymal cells. However, in most tissues EMT is a developmentally restricted process and fully differentiated epithelia typically maintain their epithelial phenotype. Recently, elements of EMT, specially the loss of epithelial markers and the gain of mesenchymal markers, have been observed in pathological states, including epithelial cancers. Increasing evidence has confirmed its presence in human colon during colorectal carcinogenesis. In general, chronic inflammation is considered to be one of the causes of many human cancers including colorectal cancer(CRC). Accordingly, epidemiologic and clinical studies indicate that patients affected by ulcerative colitis and Crohn's disease, the two major forms of inflammatory bowel disease, have an increased risk of developing CRC. A large body of evidence supports roles for the SMAD/STAT3 signaling pathway, the NF-kB pathway, the Ras-mitogen- activated protein kinase/Snail/Slug and microRNAs in the development of colorectal cancers via epithelial-to- mesenchymal transition. Thus, EMT appears to be closely involved in the pathogenesis of colorectal cancer, and analysis refered to it can yield novel targets for therapy.