SFRP2 and slug contribute to cellular resistance to apoptosis in hypertrophic scars

SFRP2 modulates functional phenotype transition and energy metabolism of macrophages during diabetic wound healing

Diabetic foot ulcer (DFU) is a serious complication of diabetes mellitus, which causes great health damage and economic burden to patients. The pathogenesis of DFU is not fully understood. We screened wound healing-related genes using bioinformatics analysis, and full-thickness skin injury mice model and cellular assays were used to explore the role of target genes in diabetic wound healing. SFRP2 was identified as a wound healing-related gene, and the expression of SFRP2 is associated with immune cell infiltration in DFU. In vivo study showed that suppression of SFRP2 delayed the wound healing process of diabetic mice, impeded angiogenesis and matrix remodeling, but did not affect wound healing process of control mice. In addition, suppression of SFRP2 increased macrophage infiltration and impeded the transition of macrophages functional phenotypes during diabetic wound healing, and affected the transcriptome signatures-related to inflammatory response and energy metabolism at the early stage of wound healing. Extracellular flux analysis (EFA) showed that suppression of SFRP2 decreased mitochondrial energy metabolism and increased glycolysis in injury-related macrophages, but impeded both glycolysis and mitochondrial energy metabolism in inflammatory macrophages. In addition, suppression of SFRP2 inhibited wnt signaling-related genes in macrophages. Treatment of AAV-SFRP2 augmented wound healing in diabetic mice and demonstrated the therapeutic potential of SFRP2. In conclusions, SFRP2 may function as a wound healing-related gene in DFU by modulating functional phenotype transition of macrophages and the balance between mitochondrial energy metabolism and glycolysis.

Skin fibrosis is accompanied by increased expression of secreted frizzled-related protein-2

Dermal fibrosis is a consequence of damage to skin and is accompanied by dysfunction and cosmetic disfigurement. Improved understanding of the pathological factors driving skin fibrosis is critical to development of therapeutic modalities. Here, we describe that the Wnt signalling antagonist SFRP2 is upregulated in organotypic keratinocyte cultures upon experimental reduced hydration, a model that simulates the aberrant epidermal barrier state characteristic of several skin pathologies, including those that manifest in development of fibrosis. Consistent with this, we find that SFRP2 is overexpressed in both the dermis and epidermis of human hypertrophic scar tissue and lesional tissue of a mouse scleroderma model. Knockdown of SFRP2 expression in human fibroblasts antagonises proliferation and myofibroblast differentiation, including deposition of type I collagen, suggesting that SFRP2 signalling in fibroblasts may contribute to propagation of fibrosis in hypertrophic scar, as well as in other clinical indications characterised by skin fibrosis.

Human fetal dermal fibroblast-myeloid cell diversity is characterized by dominance of pro-healing Annexin1-FPR1 signaling

Fetal skin achieves scarless wound repair. Dermal fibroblasts play a central role in extracellular matrix deposition and scarring outcomes. Both fetal and gingival wound repair share minimal scarring outcomes. We tested the hypothesis that compared to adult skin fibroblasts, human fetal skin fibroblast diversity is unique and partly overlaps with gingival skin fibroblasts. Human fetal skin (FS, n = 3), gingiva (HGG, n = 13), and mature skin (MS, n = 13) were compared at single-cell resolution. Dermal fibroblasts, the most abundant cluster, were examined to establish a connectome with other skin cells. Annexin1-FPR1 signaling pathway was dominant in both FS as well as HGG fibroblasts and related myeloid cells while scanty in MS fibroblasts. Myeloid-specific FPR1-ORF delivered in murine wound edge using tissue nanotransfection (TNT) technology significantly enhanced the quality of healing. Pseudotime analyses identified the co-existence of an HGG fibroblast subset with FPR1high myeloid cells of fetal origin indicating common underlying biological processes.

The emerging therapeutic targets for scar management: genetic and epigenetic landscapes

Background

Wound healing is a complex process including hemostasis, inflammation, proliferation, and remodeling during which an orchestrated array of biological and molecular events occurs to promote skin regeneration. Abnormalities in each step of the wound healing process lead to reparative rather than regenerative responses, thereby driving the formation of cutaneous scar. Patients suffering from scars represent serious health problems such as contractures, functional and esthetic concerns as well as painful, thick, and itchy complications, which generally decrease the quality of life and impose high medical costs. Therefore, therapies reducing cutaneous scarring are necessary to improve patients' rehabilitation.

Summary

Current approaches to remove scars, including surgical and nonsurgical methods, are not efficient enough, which is in principle due to our limited knowledge about underlying mechanisms of pathological as well as the physiological wound healing process. Thus, therapeutic interventions focused on basic science including genetic and epigenetic knowledge are recently taken into consideration as promising approaches for scar management since they have the potential to provide targeted therapies and improve the conventional treatments as well as present opportunities for combination therapy. In this review, we highlight the recent advances in skin regenerative medicine through genetic and epigenetic approaches to achieve novel insights for the development of safe, efficient, and reproducible therapies and discuss promising approaches for scar management.

Key Message

Genetic and epigenetic regulatory switches are promising targets for scar management, provided the associated challenges are to be addressed.

The influence of GSTT/GSTM null genotypes in scarring

Background and aims

The process of scarring is a common denominator of interest for the medical field. From general medicine to dentistry, pathological scar tissue represents a challenge in providing optimal care to a patient. The present study aims to investigate whether a systemically reduced antioxidant potential, revealed by null isoforms of glutathione S transferase, affects the process of scarring in a group of female patients.

Methods

The study is based on a group of 54 patients with physiological scars after a 6-month observation period, as well as 18 patients with hypertrophic or atrophic scars. Peripheral venous blood was collected, from which DNA was extracted using a commercial kit. Genotyping followed a Multiplex PCR protocol for GSTT1/GSTM1.

Results

In a dominant model, the combination of wild type (heterozygous or homozygous) GSTT1 and GSTM1 was negatively associated with pathological scarring, with the wild type (heterozygous or homozygous) GSTM1 genotype being potentially responsible for this effect. Other factors affecting pathological scarring were investigated: family history, phototype, as well as scores on the POSAS and SCAR scales.

Conclusions

The presence of GSTT1 and GSTM1 alleles brings forward an increased antioxidant capacity, serving as a protective factor for patients during scar formation.

Histological and Gene Expression Analysis of the Effects of Menopause Status and Hormone Therapy on the Vaginal Introitus and Labia Majora

Background

The study aimed to determine the effect of menopausal status and hormone therapy on the introitus and labia majora at the levels of histology and gene expression.

Methods

Three cohorts of 10 women each (pre-menopause, post-menopause and post-menopause + hormone therapy) were selected based on the presentation of clinical atrophy and vaginal pH. Biopsies were obtained from the introitus (fourchette) and labia majora and processed for histology and gene expression analyses with microarrays. Other data collected included self-assessed symptoms, serum estradiol, testosterone, serum hormone binding globulin and the pH of the vagina and labia majora.

Results

The introitus appears exquisitely sensitive to hormone status. Dramatic changes were observed in histology including a thinning of the epithelium in post-menopausal subjects with vaginal atrophy. Furthermore, there was differential expression of many genes that may contribute to tissue remodeling in the atrophic introitus. Levels of expression of genes associated with wound healing, angiogenesis, cell migration/locomotion, dermal structure, apoptosis, inflammation, epithelial cell differentiation, fatty acid, carbohydrate and steroid metabolism were significantly different in the cohort exhibiting atrophy of the introitus. While changes were also observed at the labia, that site was considerably less sensitive to hormone status. The gene expression changes observed at the introitus in this study were very similar to those reported previously in the atrophic vagina providing further evidence that these changes are associated with atrophy.

Conclusions

The histological and gene expression changes occurring within the introitus after menopause may contribute to the constellation of symptoms that constitute the genitourinary syndrome of menopause.

Small interfering RNA (siRNA) against Slug induces apoptosis and sensitizes human anaplastic thyroid carcinoma cells to doxorubicin

OBJECTIVE

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human cancers and often shows resistance to multimodal therapeutic approaches. It has been shown that the transcriptional repressor Slug inhibits the chemotherapeutic agent-induced apoptosis of cancer cells. We evaluated whether targeting of Slug could augment doxorubicin (DOX)-induced apoptosis of ATC cells. We also determined changes in PUMA (p53-upregulated modulator of apoptosis) expression levels to identify possible mechanisms of their combined actions.

METHODS

SW1736 cells were transfected with Slug siRNA or/and PUMA siRNA and then exposed to DOX (0.1, 1, and 5 μ M) for selected times. Scrambled siRNA was used as a control. The effects on cell viability were determined via MTT assay. Apoptosis was assessed using TUNEL assays and annexin V staining, and was confirmed by flow cytometry analyses. Slug and PUMA levels were determined using western blotting, RT-PCR and immunofluorescence analyses. We used a subcutaneous implanted tumor model of SW1736 cells in nude mice to assess the effects of Slug silencing in combination with DOX on tumor development. Apoptosis was assessed via TUNEL assay.

RESULTS

Targeting of Slug using siRNA inhibits growth of SW1736 cells and sensitizes SW1736 cells to DOX in vitro and vivo. Targeting of Slug combined with DOX led to lower cell viability than treatment with DOX alone in SW1736 cells. TUNEL and flow cytometry analyses showed that targeting of Slug enhanced DOX-induced apoptosis of SW1736 cells. In addition, targeting of Slug increased PUMA expression, and targeting of PUMA restored the chemoresistance of SW1736/Slug siRNA cells to DOX.

CONCLUSIONS

Knockdown of Slug enhanced the antitumor activity of DOX in SW1736 cells via induction of PUMA upregulation. Our results suggest that targeting of Slug has good potential for the development of new therapeutic strategies for ATC.

Secreted Frizzled-Related Protein 2 (sFRP2) promotes osteosarcoma invasion and metastatic potential

Background

Osteosarcoma (OS), which has a high potential for developing metastatic disease, is the most frequent malignant bone tumor in children and adolescents. Molecular analysis of a metastatic genetically engineered mouse model of osteosarcoma identified enhanced expression of Secreted Frizzled-Related Protein 2 (sFRP2), a putative regulator of Wnt signaling within metastatic tumors. Subsequent analysis correlated increased expression in the human disease, and within highly metastatic OS cells. However, the role of sFRP2 in osteosarcoma development and progression has not been well elucidated.

Methods

Studies using stable gain or loss-of-function alterations of sFRP2 within human and mouse OS cells were performed to assess changes in cell proliferation, migration, and invasive ability in vitro, via both transwell and 3D matrigel assays. In additional, xenograft studies using overexpression of sFRP2 were used to assess effects on in vivo metastatic potential.

Results

Functional studies revealed stable overexpression of sFRP2 within localized human and mouse OS cells significantly increased cell migration and invasive ability in vitro and enhanced metastatic potential in vivo. Additional studies exploiting knockdown of sFRP2 within metastatic human and mouse OS cells demonstrated decreased cell migration and invasion ability in vitro, thus corroborating a critical biological phenotype carried out by sFRP2. Interestingly, alterations in sFRP2 expression did not alter OS proliferation rates or primary tumor development.

Conclusions

While future studies further investigating the molecular mechanisms contributing towards this sFRP2-dependent phenotype are needed, our studies clearly provide evidence that aberrant expression of sFRP2 can contribute to the invasive and metastatic potential for osteosarcoma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2909-6) contains supplementary material, which is available to authorized users.

Targeting of slug sensitizes anaplastic thyroid carcinoma SW1736 cells to doxorubicin via PUMA upregulation

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human cancers and often shows resistance to multimodal therapeutic approaches. It has been shown that the transcriptional repressor Slug inhibits the chemotherapeutic agent-induced apoptosis of cancer cells. We evaluated whether targeting of Slug could augment doxorubicin (DOX)-induced apoptosis of ATC cells. We also determined changes in PUMA (p53-upregulated modulator of apoptosis) expression levels to identify possible mechanisms of their combined actions. Methods SW1736 cells were transfected with Slug siRNA or/and PUMA siRNA and then exposed to DOX (0.1, 1, and 5 mM) for selected times. Scrambled siRNA was used as a control. The effects on cell viability were determined via MTT assay. Apoptosis was assessed using TUNEL assays and annexin V staining, and was confirmed by flow cytometry analyses. Slug and PUMA levels were determined using western blotting and immunofluorescence analyses. We used a subcutaneous implanted tumor model of SW1736 cells in nude mice to assess the effects of Slug silencing in combination with DOX on tumor development. Apoptosis was assessed via TUNEL assay. Results Targeting of Slug using siRNA combined with DOX led to lower cell viability than treatment with DOX alone in SW1736 cells. TUNEL and flow cytometry analyses showed that targeting of Slug enhanced DOX-induced apoptosis of SW1736 cells. In addition, targeting of Slug increased PUMA expression, and targeting of PUMA restored the chemoresistance of SW1736/Slug siRNA cells to DOX. Conclusions Knockdown of Slug enhanced the antitumor activity of DOX in SW1736 cells via induction of PUMA upregulation. Our results suggest that targeting of Slug has good potential for the development of new therapeutic strategies for ATC.

Loss of Sfrp2 in the Niche Amplifies Stress-Induced Cellular Responses, and Impairs the In Vivo Regeneration of the Hematopoietic Stem Cell Pool

Sfrp2 is overexpressed in stromal cells which maintain hematopoietic stem cells (HSCs) during in vitro culture. We here showed, that coculture of hematopoetic cells with stromal cells with reduced expression of Sfrp2 increases the number lineage-negative Kit(+) Sca-1(+) (LSK) and progenitor cells in vitro. The LSK cells from these cocultures showed activation of canonical Wnt signaling, higher levels of Ki-67, BrdU incorporation, and the number of γH2A.X positive foci. Total repopulating activity of these cultures was, however, diminished, indicating loss of HSC. To extend these in vitro data, we modelled stress in vivo, i.e., by aging, or 5-FU treatment in Sfrp2(-) (/) (-) mice, or replicative stress in regeneration of HSCs in Sfrp2(-) (/) (-) recipients. In all three in vivo stress situations, we noted an increase of LSK cells, characterized by increased levels of β-catenin and cyclin D1. In the transplantation experiments, the increase in LSK cells in primary recipients was subsequently associated with a progressive loss of HSCs in serial transplantations. Similar to the in vitro coculture stress, in vivo genotoxic stress in 5-FU-treated Sfrp2(-) (/) (-) mice increased cell cycle activity of LSK cells with higher levels of BrdU incorporation, increased expression of Ki-67, and canonical Wnt signaling. Importantly, as noted in vitro, increased cycling of LSKs in vivo was accompanied by a defective γH2A.X-dependent DNA damage response and depolarized localization of acetylated H4K16. Our experiments support the view that Sfrp2 expression in the niche is required to maintain the HSC pool by limiting stress-induced DNA damage and attenuating canonical Wnt-mediated HSC activation. Stem Cells 2016;34:2381-2392.

Secreted Frizzled-Related Protein 2 (sFRP2) Functions as a Melanogenic Stimulator; the Role of sFRP2 in UV-Induced Hyperpigmentary Disorders

In this study, we found that secreted frizzled-related protein 2 (sFRP2) is overexpressed in the hyperpigmentary skin of melasma and solar lentigo and in acutely UV-irradiated skin. To investigate the effect of sFRP2 on melanogenesis, normal human melanocytes were infected with sFRP2-lentivirus or sh-sFRP2. It was found that sFRP2 stimulates melanogenesis through microphthalmia-associated transcription factor and/or tyrosinase upregulation via β-catenin signaling. The stimulatory action of sFRP2 in pigmentation was further confirmed in melanocytes cocultured with fibroblasts and in ex vivo cultured skin. The findings suggest that sFRP2 functions as a melanogenic stimulator and that it plays a role in the development of UV-induced hyperpigmentary disorders.

Healed porcine incisions previously treated with a surgical incision management system: mechanical, histomorphometric, and gene expression properties

BACKGROUND

Computer and bench models have shown previously that surgical incision management with negative pressure (SIM) immediately decreases lateral tissue tension and increases incisional apposition. Better apposition is known to improve healing. Thus, SIM was hypothesized to improve the quality of incisional healing. This study evaluated the impact that 5 days of SIM had on mechanical properties and associated changes in the histology/histomorphometry and gene expression of healed porcine incisions.

METHODS

One incision in each of the 4 pairs of contralateral, sutured, full-thickness incisions in each of 6 Yucatan swine were treated with either SIM (Prevena™ Incision Management System; n = 24 incisions/treatment group) or standard of care (SOC; sterile absorbent abdominal pads; n = 24/group) for 5 days, after which both groups received SOC for an additional 5 days. Biopsies for gene-expression analyses were collected on days 5 (n = 6 pairs/group), 20 (n = 6 pairs/group), and 40 (n = 12 pairs/group). On day 40, the animals were killed, after which healed incisions were harvested for mechanical testing (n = 12/group) and histologic/histomorphometric evaluation (n = 12/group).

RESULTS

Compared with SOC-treated incisions, SIM-treated incisions had significantly improved (p < 0.05) mechanical properties (strain energy density, peak strain) and a narrower scar/healed area in the deep dermis on day 40. Differences in gene expression between SOC- and SIM-treated specimens were observed primarily on day 5. The SIM-treated specimens had significantly fewer genes, which were differentially expressed and showed reduced upregulation of genes associated with inflammation, hypoxia, retardation of reepithelialization, impaired wound healing, and scarring.

CONCLUSION

Early application of SIM improved the quality of healed porcine incisions in terms of mechanical, histomorphometric, and gene-expression properties.

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