Wnt-β Catenin Signaling Pathway: A Major Player in the Injury Induced Fibrosis and Dysfunction of the External Anal Sphincter

Targeting Signaling Pathway by Curcumin in Osteosarcoma

The most prevalent primary bone malignancy among children and adolescents is osteosarcoma. The high mortality rate of osteosarcoma is due to lung metastasis. Despite the development of multi-agent chemotherapy and surgical resection, patients with osteosarcoma have a high metastasis rate and poor prognosis. Thus, it is necessary to identify novel therapeutic agents to improve the 5-year survival rate of these patients. Curcumin, a phytochemical compound derived from Curcuma longa, has been employed in treating several types of cancers through various mechanisms. Also, in vitro studies have demonstrated that curcumin could inhibit cell proliferation and induce apoptosis in osteosarcoma cells. Development in identifying signaling pathways involved in the pathogenesis of osteosarcoma has provided insight into finding new therapeutic targets for the treatment of this cancer. Targeting MAPK/ERK, PI3k/AKT, Wnt/β-catenin, Notch, and MircoRNA by curcumin has been evaluated to improve outcomes in patients with osteosarcoma. Although curcumin is a potent anti-cancer compound, it has rarely been studied in clinical settings due to its congenital properties such as hydrophobicity and poor bioavailability. In this review, we recapitulate and describe the effect of curcumin in regulating signaling pathways involved in osteosarcoma.

Current and future perspectives on the utility of provocative tests of anal sphincter function: A state-of-the-art summary

BACKGROUND

The maintenance of fecal continence depends upon coordinated interactions between the pelvic floor, anorectum, and anal sphincter complex orchestrated by central and peripheral neural activities. The current techniques to objectively measure anorectal function rely on fixed diameter catheters placed inside the anal canal with a rectal balloon to obtain measurements of anal resting and squeeze function, and rectal compliance. Until recently it had not been possible to measure the distensibility of the anal canal, or in other words its ability to resist opening against an increasing pressure, which has been proposed as the main determinant of a biological sphincter's function. Anal acoustic reflectometry (AAR) and the functional lumen imaging probe (FLIP) are two novel, provocative techniques that dynamically assess the anal sphincter complex under volume-controlled distension. In doing so, both provide information on the viscoelastic properties of the anal canal and offer new insights into its function.

PURPOSE

This review details the current and potential future applications of AAR and FLIP and highlights the unanswered questions relevant to these new technologies.

Implant of Self-Expandable Artificial Anal Sphincter in Patients With Fecal Incontinence Improves External Anal Sphincter Contractility

BACKGROUND

External anal sphincter contractility significantly contributes to control the passage of stool. An artificial anal sphincter placed into the intersphincteric space is a safe and effective procedure to treat fecal incontinence, even if its mechanism of action has not been fully elucidated.

OBJECTIVE

The aim of this study was to evaluate external anal sphincter contractility changes after a self-expandable hyexpan prostheses was implanted into the intersphincteric space of the anal canal and clinical outcomes compared.

DESIGN

This was a prospective clinical study.

SETTINGS

The study was conducted at a university teaching hospital.

PATIENTS

Consecutive patients affected by fecal incontinence for at least 6 months after failure of conservative treatment were included.

INTERVENTIONS

All of the patients underwent 10-prostheses implantation and were examined preoperatively and postoperatively by endoanal ultrasound and anorectal manometry.

MAIN OUTCOME MEASURES

Fecal incontinence symptoms were assessed by severity scores. The external anal sphincter muscle tension was calculated using a specific equation.

RESULTS

Thirty-nine patients (34 women; median age = 68 y) were included in the study; no morbidity was registered. After a median follow-up period of 14 months, both the median maximum voluntary squeeze pressure and the median inner radius of the external anal sphincter significantly increased. A statistically significant increase of external anal sphincter muscle tension was detected. A decrease of any fecal incontinence symptom and an improvement in severity scores were observed at the last follow-up examination. The external anal sphincter contractility was significantly higher in patients reducing incontinence episodes to solid stool by >50% and improving their ability to defer defecation for >15 minutes.

LIMITATIONS

This was a single-center experience with a relatively small and heterogeneous sample size, patients with a potentially more severe disease because our institution is a referral center, and an absence of quality-of-life evaluation.

CONCLUSIONS

Artificial anal sphincter implantation improved the external anal sphincter muscle tension; there was a positive correlation between its increase and the clinical outcome. See Video Abstract at http://links.lww.com/DCR/B468.

IMPLANTE DE ESFNTER ANAL ARTIFICIAL AUTOEXPANDIBLE EN PACIENTES CON INCONTINENCIA FECAL MEJORA LA CONTRACTILIDAD DEL ESFNTER ANAL EXTERNO

ANTECEDENTES:La contractilidad del esfínter anal externo contribuye significativamente al control del paso de las heces. Un esfínter anal artificial colocado en el espacio interesfinteriano es un procedimiento seguro y eficaz para tratar la incontinencia fecal, incluso si su mecanismo de acción no se ha definido por completo.OBJETIVO:El objetivo de este estudio fue evaluar los cambios en la contractilidad del esfínter anal externo después de la implantación de una prótesis de hyexpan autoexpandible en el espacio interesfinteriano del canal anal y comparar los resultados clínicos.DISEÑO:Estudio clínico prospectivo.ENTORNO CLINICO:El estudio se realizó en un hospital universitario.PACIENTES:Pacientes consecutivos afectados por incontinencia fecal durante al menos 6 meses, tras fracaso de tratamiento conservador.INTERVENCIONES:Todos los pacientes fueron sometidos a la implantación de 10 prótesis, y fueron examinados pre y postoperatoriamente mediante ecografía endoanal y manometría anorrectal.PRINCIPALES MEDIDAS DE VALORACION:Los síntomas de incontinencia fecal se evaluaron mediante puntuaciones de gravedad. La tensión del músculo del esfínter anal externo se calculó mediante una formula específica.RESULTADOS:Treinta y nueve pacientes (34 mujeres; mediana de edad 68 años) fueron incluidos en el estudio; no se registró morbilidad. Después de un período de seguimiento medio de 14 meses, tanto la presión de compresión voluntaria máxima media como el radio interior medio del esfínter anal externo aumentaron significativamente. Se detectó un aumento estadísticamente significativo de la tensión del músculo del esfínter anal externo. En el último examen de seguimiento se observó una disminución de cualquier síntoma de incontinencia fecal y una mejora en las puntuaciones de gravedad. La contractilidad del esfínter anal externo fue significativamente mayor en los pacientes que redujeron los episodios de incontinencia a heces sólidas en más del 50% y mejoraron la capacidad para diferir la defecación durante más de 15 minutos.LIMITACIONES:Experiencia de un solo centro; tamaño de muestra relativamente pequeño y heterogéneo; pacientes con una enfermedad potencialmente más grave porque nuestra institución es un centro de referencia; ausencia de evaluación de la calidad de vida.CONCLUSIONES:La implantación del esfínter anal artificial mejoró la tensión muscular del esfínter anal externo; hubo una correlación positiva entre su aumento y el resultado clínico. Consulte Video Resumen en http://links.lww.com/DCR/B468.

Multiple Roles of sFRP2 in Cardiac Development and Cardiovascular Disease

The Wnt signaling pathway plays important roles in organ development and disease processes. Secreted frizzled-related protein 2 (sFRP2), a vital molecule of Wnt signaling, can regulate cardiac development and cardiovascular disease. Recent studies have suggested that sFRP2 is not only an antagonist of the canonical Wnt signaling pathway, but also has a more complex relationship in myocardial fibrosis, angiogenesis, cardiac hypertrophy and cardiac regeneration. Here, we review the role of sFRP2 and Wnt signaling in cardiac development and cardiovascular disease.

Wnt4 negatively regulates the TGF-β1-induced human dermal fibroblast-to-myofibroblast transition via targeting Smad3 and ERK

Abnormal activation of Wnt signaling has been demonstrated in the wound healing process and the pathogenesis of fibrotic disorders, with Wnt4 specifically identified as having a key role in the pathogenesis of renal, pulmonary and liver fibrosis. Wnt4 also was found to be upregulated by transforming growth factor-β1 (TGF-β1) in fetal and postnatal murine fibroblasts and bone marrow mesenchymal cells, suggesting an underlying cooperation between Wnt4 and TGF-β1 in fibrosis. However, the specific roles of Wnt4 in TGF-β1-induced skin myofibroblast transition and hypertrophic scar formation remain unclear. In the present study, we first observed reduced Wnt4 expression in hypertrophic scar tissue compared with that in normal skin tissue. Following upregulation by TGF-β1, Wnt4 inhibited the TGF-β1-induced transdifferentiation of fibroblasts into myofibroblasts. Using fibroblast-populated collagen lattice contraction assays, we showed that the increased contractility induced by TGF-β1 was significantly blocked by exogenous Wnt4 and the α-smooth muscle actin (α-SMA) expression was decreased in fibroblasts in the collagen lattices. In addition, knockdown of Wnt4 resulted in further increases in α-SMA and collagen I expressions. Further investigation showed that Wnt4 could inhibit the autocrine effect of TGF-β1 as well as block the phosphorylation of Smad3 and ERK but not of AKT or JNK. Lastly, using hypertrophic scar-derived fibroblasts, we showed that the elevated α-SMA and collagen I levels were markedly reduced after treatment with Wnt4. Taken together, our results suggest that Wnt4 negatively regulates TGF-β1-induced fibroblast activation, which may represent a novel therapeutic strategy for the treatment and prevention of hypertrophic scars.

Crosstalk between Hh and Wnt signaling promotes osteosarcoma progression

OBJECTIVE

Osteosarcoma (OS) is the most common primary malignant tumor of bone. Patients with localized osteosarcoma are routinely treated with chemotherapy and surgery. However, many patients eventually relapse after these treatments. Therefore, it is important and urgent to identify better therapeutic strategies. Hedgehog-GLI is responsible for the development of bone and tumorigenesis. Aberrant activation of GLI-2 is correlated with various malignancies including OS.

METHODS

RT-QPCR and western blot were performed to detect the expression of GLI-2 among human osteosarcoma cell lines U2OS, SaOS and human osteoblast cells HOB-c. siRNA or overexpression method were used to knock down/overexpress GLI-2 or β-catenin and MTS formazan generation method were applied to study the function of GLI-2 and β-catenin in the proliferation of OS cells.

RESULTS

We showed that GLI-2 is highly expressed in osteosarcoma cell lines. Knockdown of GLI-2 by siRNA decreases osteosarcoma cell proliferation. Further, we showed that knockdown of GLI-2 can decrease the protein level of β-catenin, and β-catenin depletion by siRNA could decrease the proliferation of OS cells. Interestingly, overexpression of β-catenin in GLI-2 knockdown cells partially increased proliferation.

CONCLUSION

These findings suggest Hh/GLI-2-Wnt/β-catenin crosstalk is required for osteosarcoma cell proliferation. GLI-2 may play a role in the regulation of the expression of β-catenin in OS cells and β-catenin may function as downstream effector of crosstalk between Hh and Wnt signaling. GLI-2 may be exploited as a therapeutic target for the treatment of osteosarcoma patients.

Age and multiparity related urethral sphincter muscle dysfunction in a rabbit model: Potential roles of TGF-β and Wnt-β catenin signaling pathways

AIMS

Prior studies demonstrate increased incidence of urinary incontinence (UI) in the geriatric population which affects their quality of life. Pathophysiology of UI in the geriatric population and the underlying molecular mechanisms are still unclear. To elucidate these mechanisms, we performed a pre-clinical study in a rabbit model and the objectives were to (i) determine the effect of aging as well as multiparity on urethral sphincter muscle thickness and urethral closing pressure (UCP); (ii) examine the role of fibrosis and atrophy; and (iii) elucidate the molecular pathways that mediate fibrosis and atrophy in the urethral tissue.

METHODS

New Zealand White female rabbits (n = 6 each; young 6-12 months and old over 30 months of age) were anesthetized and urethral muscle thickness and sphincter closure function were measured. Rabbits were then sacrificed and urethral tissues (bladder neck and mid-urethra) were collected to process for immunostaining as well as for molecular studies for markers for fibrosis (β-catenin which is an important mediator of Wnt signaling, Collagen-1, and TGF-β) and atrophy (MuRF-1).

RESULTS

Our studies showed a significant decrease in the urethral sphincter muscle thickness and closure function with age. Age-related increase in protein and mRNA expression levels of fibrosis, as well as atrophy markers were observed in the bladder neck and mid-urethral tissues.

CONCLUSIONS

Age and multiparity related increase in fibrosis and atrophy of urethral sphincter muscles may contribute to impaired urethral closure function seen in old animals.

Sustained and Bioresponsive Two-Stage Delivery of Therapeutic miRNA via Polyplex Micelle-Loaded Injectable Hydrogels for Inhibition of Intervertebral Disc Fibrosis

Intervertebral disc degeneration (IDD) is frequently caused by gradual pathological changes inside intervertebral discs (IVDs) and progressive fibrosis. MicroRNA-29 (miR-29) family possesses potent fibrosis suppression capability, but their application for treatment of chronic IDD is limited due to lack of suitable local delivery systems. In this report, given various overexpressed matrix metalloproteinases (MMPs) during IDD, injectable MMP-degradable hydrogels encapsulating MMP-responsive polyplex micelles are developed for sustained and bioresponsive delivery of miR-29a into nucleus pulposus cells via a two-stage process. Cationic block copolymers are designed to complex miR-29a, and subsequently mixed with the poly(ethylene glycol) (PEG) gelation precursors and MMP-cleavable peptide cross-linkers for in situ formation of polyplex micelle-encapsulated hydrogels in the diseased IVDs. In the presence of MMPs, the polyplex micelles are first released by MMP cleavage of the hydrogels, and subsequently, MMPs-responsive detachment of PEG shells from polyplex micelles contributes to efficient cellular uptake and endosomal escape. MiR-29a is demonstrated to effectively silence the expression of MMP-2, inhibit the fibrosis process, and reverse IDD in animal models through blocking the β-catenin translocation pathway from the cytoplasm to the nucleus. This two-stage bioresponsive local miRNA delivery system represents a novel and promising strategy for the treatment of chronic IDD.

DNA hypermethylation of SFRP2 influences the pathology of rheumatoid arthritis through the canonical Wnt signaling in model rats

In this work, the expression of secreted frizzled related protein 2 (SFRP2) in rheumatoid arthritis (RA) model rats and the mechanisms of SFRP2 on the RA pathogenesis were investigated. Data suggested that SFRP2 was significantly down-regulated in RA model rats compared with normal control, and overexpression of SFRP2 suppressed the RA pathogenesis and the canonical Wnt signaling in fibroblast-like synovial cells (FLS) from RA model rats, whereas knockdown of SFRP2 got an opposite observation. Interestingly, 5-azadC treatment up-regulated the SFRP2 expression, inhibited the FLS proliferation, suppressed the expression of IL-6 and IL-8 and the fibronectin production, suggesting that the decreased SFRP2 in RA model rats was due to the DNA methylation. Furthermore, DNMT1 knockdown up-regulated the SFRP2 expression, DNMT1 overexpression inhibited the SFRP2, and the quantitative methylation-specific PCR (qMSP) confirmed that the DNMT1 has direct methylation roles for the SFRP2 promoter, leading to a regulation of FLS proliferation and fibronectin expression in RA model rats. In addition, up-regulated MeCP2 was involved in the SFRP2 regulation and the pathogenesis of RA model rats, and MeCP2 and DNMT1 have synergistic inhibition roles in the SFRP2 expression. Combination of DNMT1 and DNA methylation may be a promising treatment strategy for individuals with RA in which SFRP2 is down-regulated.

Age-related external anal sphincter muscle dysfunction and fibrosis: possible role of Wnt/β-catenin signaling pathways

Studies show an age-related increase in the prevalence of anal incontinence and sphincter muscle atrophy. The Wnt/β-catenin signaling pathway has been recently recognized as the major molecular pathway involved in age-related skeletal muscle atrophy and fibrosis. The goals of our study were to 1) evaluate the impact of normal aging on external anal sphincter (EAS) muscle length-tension (L-T) function and morphology and 2) specifically examine the role of Wnt signaling pathways in anal sphincter muscle fibrosis. New Zealand White female rabbits [6 young (6 mo of age) and 6 old (36 mo of age)] were anesthetized, and anal canal pressure was measured to determine the L-T function of EAS. Animals were killed at the end of the study, and the anal canal was harvested and processed for histochemical studies (Masson trichrome stain for muscle/connective tissue) as well as for molecular markers for fibrosis and atrophy [collagen I, β-catenin, transforming growth factor-β (TGF-β), atrogin-1, and muscle-specific RING finger protein-1 (MuRF-1)]. The L-T was significantly impaired in older animals compared with young animals. Anal canal sections stained with trichrome showed a significant decrease in the muscle content (52% in old compared with 70% in young) and an increase in the connective tissue/collagen content in the old animals. An increased protein and mRNA expression of all the fibrosis markers was seen in the older animals. Aging EAS muscle exhibits impairment of function and increase in connective tissue. Upregulation of atrophy and profibrogenic proteins with aging may be the reason for the age-related decrease in anal sphincter muscle thickness and function.NEW & NOTEWORTHY Our studies using a female rabbit model show age-related alterations in the structure and function of the external anal sphincter (EAS) muscle. We used endoluminal ultrasound to measure age-related changes in EAS muscle thickness. We employed Western blot and quantitative PCR to demonstrate age-related changes in the levels of important fibrogenic as well as atrophy markers. Our findings may have significant clinical implications, i.e., use of specific antagonists to prevent age-related EAS muscle dysfunction.