Akt inhibition up-regulates MMP1 through a CCN2-dependent pathway in human dermal fibroblasts

Network medicine based approach for identifying the type 2 diabetes, osteoarthritis and triple negative breast cancer interactome: Finding the hub of hub genes

The increasing prevalence of multi-morbidities, particularly the incidence of breast cancer in diabetic/osteoarthritic patients emphasize on the need for exploring the underlying molecular mechanisms resulting in carcinogenesis. To address this, present study employed a systems biology approach to identify switch genes pivotal to the crosstalk between diseased states resulting in multi-morbid conditions. Hub genes previously reported for type 2 diabetes mellitus (T2DM), osteoarthritis (OA), and triple negative breast cancer (TNBC), were extracted from published literature and fed into an integrated bioinformatics analyses pipeline. Thirty-one hub genes common to all three diseases were identified. Functional enrichment analyses showed these were mainly enriched for immune and metabolism associated terms including advanced glycation end products (AGE) pathways, cancer pathways, particularly breast neoplasm, immune system signalling and adipose tissue. The T2DM-OA-TNBC interactome was subjected to protein-protein interaction network analyses to identify meta hub/clustered genes. These were prioritized and wired into a three disease signalling map presenting the enriched molecular crosstalk on T2DM-OA-TNBC axes to gain insight into the molecular mechanisms underlying disease-disease interactions. Deciphering the molecular bases for the intertwined metabolic and immune states may potentiate the discovery of biomarkers critical for identifying and targeting the immuno-metabolic origin of disease.

Thymosin beta-4 improves endothelial function and reparative potency of diabetic endothelial cells differentiated from patient induced pluripotent stem cells

Background

Prior studies show that signature phenotypes of diabetic human induced pluripotent stem cells derived endothelial cells (dia-hiPSC-ECs) are disrupted glycine homeostasis, increased senescence, impaired mitochondrial function and angiogenic potential as compared with healthy hiPSC-ECs. In the current study, we aimed to assess the role of thymosin β-4 (Tb-4) on endothelial function using dia-hiPSC-ECs as disease model of endothelial dysfunction.

Methods and results

Using dia-hiPSC-ECs as models of endothelial dysfunction, we determined the effect of Tb-4 on cell proliferation, senescence, cyto-protection, protein expression of intercellular adhesion molecule-1 (ICAM-1), secretion of endothelin-1 and MMP-1, mitochondrial membrane potential, and cyto-protection in vitro and angiogenic potential for treatment of ischemic limb disease in a mouse model of type 2 diabetes mellitus (T2DM) in vivo. We found that 600 ng/mL Tb4 significantly up-regulated AKT activity and Bcl-XL protein expression, enhanced dia-hiPSC-EC viability and proliferation, limited senescence, reduced endothelin-1 and MMP-1 secretion, and improved reparative potency of dia-hiPSC-ECs for treatment of ischemic limb disease in mice with T2DM. However, Tb4 had no effect on improving mitochondrial membrane potential and glycine homeostasis and reducing intercellular adhesion molecule-1 protein expression in dia-hiPSC-ECs.

Conclusions

Tb-4 improves endothelial dysfunction through enhancing hiPSC-EC viability, reducing senescence and endothelin-1 production, and improves angiogenic potency in diabetes.

Epigallocatechin-3-Gallate Suppresses the Expression of TNF-α-Induced MMP-1 via MAPK/ERK Signaling Pathways in Human Dermal Fibroblasts

Deeper wrinkles and loss of elasticity are one of the skin-aging symptoms. Collagen breakdown by matrix metalloproteinase-1 (MMP-1), which is induced by reactive oxygen species (ROS) and pro-inflammatory cytokines, has been known to be responsible for these skin-aging symptoms. Therefore, much attention has been paid to chemicals to suppress the MMP-1 activity. Epigallocatechin-3-gallate (EGCG), catechin rich in green tea, has been reported to show antioxidant and protect skin from various stimuli such as UV and chemicals. In this study, we evaluated the inhibitory effect of EGCG on MMP-1 gene expression and secretion in tumor necrosis factor-α (TNF-α)-treated human dermal fibroblast cells (Hs68 cells). Pre-treatment with EGCG (10 and 20 µM) suppressed TNF-α-induced MMP-1 expression and secretion. EGCG also reduced the phosphorylation of extracellular signal regulated kinase (ERK) significantly but not that of p38 activation and c-Jun N-terminal kinase (JNK). Besides, EGCG (10 and 20 µM) showed the inhibitory effect on mitogen-activated protein extracellular kinase (MEK) and Src phosphorylation which is reported to be upstream signal proteins of ERK signal pathway. Based on these results, EGCG might have potential activity to slow down the skin-aging through inhibition of collagen breakdown, which remains to be elucidated.

Inhibited effect of an RGD peptide hydrogel on the expression of β1-integrin, FAK, and Akt in Tenon's capsule fibroblasts

Tenon's capsule fibroblasts are the main cellular components of filtration tract scar that limit the success rate of glaucoma filtration surgery. Scar formation results from infiltration and proliferation of fibroblasts into damaged areas, meanwhile synthesis of extracellular matrix glycoproteins. Integrins are cell surface receptors for extracellular molecules that mediate cell adhesion, spreading, migration, and invasion. They bind their ligands often through recognition of short amino-acid sequences-arginine-glycine-aspartic acid (RGD). Peptides that contain RGD sequence can compete with RGD containing insoluble matrix proteins for binding to the integrin receptor and thus prevent the downstream signaling pathway. Increasing evidence supports that β1-integrin/focal adhesion kinase (FAK)/Akt signal pathway plays an important role in fibrogenesis and scar formation in different tissues. In consideration of advantages of peptide hydrogel, that is well biocompatibility, gel state, degradability, good drug loading, we designed and fabricated an RGD peptide hydrogel, and hypothesized that it could inhibit the expression of β1-integrin, FAK, and Akt in Tenon's capsule fibroblasts. Rheology results showed that 1% wt Fmoc-FFGGRGD peptide solution could self-assemble into hydrogel. Western blot analysis revealed that there were statistical differences between control group and 1% wt group in β1-integrin/β-actin, FAK/β-actin, Akt/β-actin respectively (*p < .05). The relative mRNA expression of β1-integrin, FAK, Akt in control group and 1% wt group were also statistically different respectively (*p < .05). We proved that 1% wt Fmoc-FFGGRGD self-assembly peptide hydrogel could inhibit the expression of β1-integrin, FAK and Akt in Tenon's capsule fibroblasts. It is a promising way to solve scar formation of glaucoma filter channel.

Chronic exposure of interleukin-13 suppress the induction of matrix metalloproteinase-1 by tumour necrosis factor α in normal and scleroderma dermal fibroblasts through protein kinase B/Akt

Peripheral blood mononuclear cells taken from patients with scleroderma express increased levels of interleukin (IL)-13. Moreover, the expression of matrix metalloproteinase-1 (MMP-1) from involved scleroderma skin fibroblasts is refractory to stimulation by tumour necrosis factor (TNF)-α. To elucidate the mechanism(s) involved, we examined the effect of IL-13 on TNF-α-induced MMP-1 expression in normal and scleroderma human dermal fibroblast lines and studied the involvement of serine/threonine kinase B/protein kinase B (Akt) in this response. Dermal fibroblast lines were stimulated with TNF-α in the presence of varying concentrations of IL-13. Total Akt and pAkt were quantitated using Western blot analyses. Fibroblasts were treated with or without Akt inhibitor VIII in the presence of IL-13 followed by TNF-α stimulation. MMP-1 expression was analysed by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Statistical analysis was performed using analysis of variance (anova) or Student's t-test. Upon TNF-α stimulation, normal dermal fibroblasts secrete more MMP-1 than systemic sclerosis (SSc) fibroblasts. This increase in MMP-1 is lost when fibroblasts are co-incubated with IL-13 and TNF-α. IL-13 induced a significant increase in levels of pAkt in dermal fibroblasts, while Akt inhibitor VIII reversed the suppressive effects of IL-13 on the response of cultured fibroblasts to TNF-α, increasing their expression of MMP-1. We show that IL-13 suppresses MMP-1 in TNF-α-stimulated normal and scleroderma dermal fibroblast. Akt inhibitor VIII is able to reverse the suppressive effect of IL-13 on MMP-1 expression and protein synthesis. Our data suggest that IL-13 regulates MMP-1 expression in response to TNF-α through an Akt-mediated pathway and may play a role in fibrotic diseases such as scleroderma.

The role of the transcription factor Ets1 in carcinoma

Ets1 belongs to the large family of the ETS domain family of transcription factors and is involved in cancer progression. In most carcinomas, Ets1 expression is linked to poor survival. In breast cancer, Ets1 is primarily expressed in the triple-negative subtype, which is associated with unfavorable prognosis. Ets1 contributes to the acquisition of cancer cell invasiveness, to EMT (epithelial-to-mesenchymal transition), to the development of drug resistance and neo-angiogenesis. The aim of this review is to summarize the current knowledge on the functions of Ets1 in carcinoma progression and on the mechanisms that regulate Ets1 activity in cancer.

PDK1 controls upstream PI3K expression and PIP3 generation

The PI3K/PDK1/Akt signaling axis is centrally involved in cellular homeostasis and controls cell growth and proliferation. Due to its key function as regulator of cell survival and metabolism, the dysregulation of this pathway is manifested in several human pathologies including cancers and immunological diseases. Thus, current therapeutic strategies target the components of this signaling cascade. In recent years, numerous feedback loops have been identified that attenuate PI3K/PDK1/Akt-dependent signaling. Here, we report the identification of an additional level of feedback regulation that depends on the negative transcriptional control of phosphatidylinositol 3-kinase (PI3K) class IA subunits. Genetic deletion of 3-phosphoinositide-dependent protein kinase 1 (PDK1) or the pharmacological inhibition of its downstream effectors, that is, Akt and mammalian target of rapamycin (mTOR), relieves this suppression and leads to the upregulation of PI3K subunits, resulting in enhanced generation of phosphatidylinositol-3,4,5-trisphosphate (PIP3). Apparently, this transcriptional induction is mediated by the concerted action of different transcription factor families, including the transcription factors cAMP-responsive element-binding protein and forkhead box O. Collectively, we propose that PDK1 functions as a cellular sensor that balances basal PIP3 generation at levels sufficient for survival but below a threshold being harmful to the cell. Our study suggests that the efficiency of therapies targeting the aberrantly activated PI3K/PDK1/Akt pathway might be increased by the parallel blockade of feedback circuits.

Cyclic mechanical stress downregulates endothelin-1 and its responsive genes independently of TGFβ1 in dermal fibroblasts

Mechanical forces are highly variable ranging from the ubiquitous gravity force to compression, fluid shear, torsion, tension and other forms. Mechanical forces act on cells and modulate their biological responses by regulating gene transcription, enzyme and growth factor activity. In soft connective tissues, formation of myofibroblasts strictly requires a mechanically loaded environment in addition to local transforming growth factor (TGF)-β activity, which itself can be modulated by the mechanical status of the environment. The aim of this study was to monitor the adaptive responses of primary dermal fibroblasts towards cyclic mechanical stress under conditions of high force to better understand the regulation of gene expression in normal skin and mechanisms of gene regulation in mechanically altered fibrotic skin. Primary murine dermal fibroblasts were exposed to equi-biaxial tensile strain. Cyclic mechanical tension was applied at a frequency of 0.1 Hz (6× /min) for 24 h with a maximal increase in surface area of 15%. This treatment resulted in downregulation of alpha smooth muscle actin (αSMA) and connective tissue growth factor (CTGF) but not of TGFβ1 expression. Cyclic strain also strongly reduced endothelin-1 (ET-1) expression and supplementing strained cultures with exogenous ET-1 rescued αSMA and CTGF levels. Of note, no biologically significant levels of TGFβ1 activity were detected in strained cultures. We provide evidence for a novel, TGFβ1-independent mechanism regulating ET-1 expression in dermal fibroblasts by biomechanical forces. Modulation of ET-1-dependent activities regulates downstream fibrotic marker genes; this pathway might therefore provide an approach to attenuate myofibroblast differentiation.

Elevated expression of cav-1 in a subset of SSc fibroblasts contributes to constitutive Alk1/Smad1 activation

Previous studies have shown that the transforming growth factor (TGF)β/Alk1/Smad1 signaling pathway is constitutively activated in a subset of systemic sclerosis (SSc) fibroblasts and this pathway is a critical regulator of CCN2 gene expression. Caveolin-1 (cav-1), an integral membrane protein and the main component of caveolae, has also been implicated in SSc pathogenesis. This study was undertaken to evaluate the role of caveolin-1 in Smad1 signaling and CCN2 expression in healthy and SSc dermal fibroblasts. We show that a significant subset of SSc dermal fibroblasts has up-regulated cav-1 expression in vitro, and that cav-1 up-regulation correlates with constitutive Smad1 phosphorylation. In addition, basal levels of phospho-Smad1 were down-regulated after inhibition of cav-1 in SSc dermal fibroblasts. Caveolin-1 formed a protein complex with Alk1 in dermal fibroblasts, and this association was enhanced by TGFβ. By using siRNA against cav-1 and adenoviral cav-1 overexpression we demonstrate that activation of Smad1 in response to TGFβ requires cav-1 and that cav-1 is sufficient for Smad-1 phosphorylation. We also show that cav-1 is a positive regulator of CCN2 gene expression, and that it is required for the basal and TGFβ-induced CCN2 levels. In conclusion, this study has revealed an important role of cav-1 in mediating TGFβ/Smad1 signaling and CCN2 gene expression in healthy and SSc dermal fibroblasts.

Ciprofloxacin has antifibrotic effects in scleroderma fibroblasts via downregulation of Dnmt1 and upregulation of Fli1

Systemic sclerosis (SSc) is characterized by fibrosis of the skin and internal organs. The present study was undertaken to examine the effects of ciprofloxacin, a fluoroquinolone antibiotic implicated in matrix remodeling, on dermal and lung fibroblasts obtained from SSc patients. Dermal and lung fibroblasts from SSc patients and healthy subjects were treated with ciprofloxacin. Western blotting was used to analyze protein levels and RT-PCR was used to measure mRNA expression. The pharmacologic inhibitor UO126 was used to block Erk1/2 signaling. SSc dermal fibroblasts demonstrated a significant decrease in collagen type I mRNA and protein levels after antibiotic treatment, while healthy dermal fibroblasts were less sensitive to ciprofloxacin, downregulating collagen only at the protein levels. Connective tissue growth factor (CCN2) gene expression was significantly reduced and matrix metalloproteinase 1 (MMP1) levels were enhanced after ciprofloxacin treatment to a similar extent in healthy and SSc fibroblasts. Ciprofloxacin induced Erk1/2 phosphorylation, and Erk1/2 blockade completely prevented MMP1 upregulation. However, Smad1 and Smad3 activation in response to TGFβ was not affected. The expression of friend leukemia integration factor 1 (Fli1), a transcriptional repressor of collagen, was increased after treatment with ciprofloxacin only in SSc fibroblasts, and this was accompanied by a decrease in the levels of DNA methyltransferase 1 (Dnmt1). Similar effects were observed in SSc-interstitial lung disease (ILD) lung fibroblasts. In summary, our study demonstrates that ciprofloxacin has antifibrotic actions in SSc dermal and lung fibroblasts via the downregulation of Dnmt1, the upregulation of Fli1 and induction of MMP1 gene expression via an Erk1/2-dependent mechanism. Thus, our data suggest that ciprofloxacin may be an attractive therapy for SSc skin and lung fibrosis.

Bioactive reagents used in mesotherapy for skin rejuvenation in vivo induce diverse physiological processes in human skin fibroblasts in vitro- a pilot study

The promise of mesotherapy is maintenance and/or recovery of a youthful skin with a firm, bright and moisturized texture. Currently applied medications employ microinjections of hyaluronic acid, vitamins, minerals and amino acids into the superficial layer of the skin. However, the molecular and cellular processes underlying mesotherapy are still elusive. Here we analysed the effect of five distinct medication formulas on pivotal parameters involved in skin ageing, that is collagen expression, cell proliferation and morphological changes using normal human skin fibroblast cultures in vitro. Whereas in the presence of hyaluronic acid, NCTF135(®) and NCTF135HA(®) , cell proliferation was comparable to control cultures; however, with higher expression of collagen type-1, matrix metalloproteinase-1 and tissue inhibitor of matrix metalloproteinase-1, addition of Soluvit(®) N and Meso-BK led to apoptosis and/or necrosis of human fibroblasts. The data indicate that bioactive reagents currently applied for skin rejuvenation elicit strikingly divergent physiological processes in human skin fibroblast in vitro.

Caveolin-1 is a negative regulator of MMP-1 gene expression in human dermal fibroblasts via inhibition of Erk1/2/Ets1 signaling pathway

BACKGROUND

Caveolar raft domains, also termed caveolae, are flask shaped invaginations that require the expression of the structural protein caveolin-1 (cav-1). Matrix metalloproteinase 1 (MMP-1) is a collagenase capable of degrading insoluble triple helical collagens. Deregulation of MMP-1 contributes to various pathological processes, including tissue fibrosis and impaired wound healing.

OBJECTIVE

In this study we investigated the role of cav-1 in MMP-1 gene regulation in human dermal fibroblasts.

METHODS

Fibroblasts were isolated from healthy subjects. Western blot was used to analyze protein levels and quantitative real time RT-PCR was used to measure mRNA expression. Cells were transiently transfected with siRNA oligos against acid sphingomyelinase (ASMase) and cav-1, or transduced with adenoviruses overexpressing ASMase and cav-1. The specific pharmacological inhibitors UO126 and SP600125 were used to block Erk1/2 and JNK activity.

RESULTS

This study shows that siRNA-mediated depletion of ASMase or cav-1, results in upregulation of MMP-1 gene expression. Similarly, MMP-1 expression was decreased after overexpresssion of cav-1 via an adenoviral vector. Depletion of cav-1 had no effect on JNK phosphorylation, while it resulted in an increase in Erk1/2 and Ets1 phosphorylation levels. Furthermore, in cav-1 depleted cells treated with the Erk inhibitor UO126, there was no increase in the levels of phospho-Erk1/2, phospho-Ets1, and MMP-1, suggesting that cav-1 mediated effects on MMP-1 and phospho-Ets1 are Erk1/2 dependent.

CONCLUSIONS

In conclusion, this study has revealed an important role for cav-1 as a negative regulator of MMP-1 gene expression via inhibition of Erk1/2/Ets1 signaling. Cav-1 could potentially be a therapeutic target in diseases with deregulated extracellular matrix (ECM) turnover.

The c-Abl tyrosine kinase controls protein kinase Cδ-induced Fli-1 phosphorylation in human dermal fibroblasts

OBJECTIVE

We have previously demonstrated that in response to transforming growth factor β (TGFβ), Fli-1 activity is repressed through a series of sequential posttranslational modifications, consisting of protein kinase Cδ (PKCδ)-induced Thr312 phosphorylation, acetylation by p300/CREB binding protein-associated factor, and detachment from the collagen promoter. The purpose of this study was to further investigate the upstream events that lead to Fli-1 phosphorylation in response to TGFβ.

METHODS

Dermal fibroblasts were isolated from systemic sclerosis (SSc) patients and healthy control subjects matched for age, sex, and ethnicity. Western blotting was used to analyze protein levels and real-time quantitative reverse transcription-polymerase chain reaction analysis was used to measure messenger RNA expression. Cells were transduced with constitutively active PKCδ adenovirus or were transiently transfected with a Bcr-Abl-overexpressing plasmid. Subcellular localization of PKCδ was examined by immunocytochemistry.

RESULTS

Western blot analysis of cell lysates demonstrated that the levels of phospho-Fli-1 (Thr312) were up-regulated in SSc fibroblasts, correlating with increased levels of type I collagen and c-Abl protein. Experiments using a constitutively activated form of c-Abl, small interfering RNA against c-Abl and the specific tyrosine kinase inhibitor imatinib, demonstrated the requirement of c-Abl for the TGFβ-induced phosphorylation of Fli-1. Additionally, we showed that c-Abl kinase activity was required for nuclear localization of PKCδ.

CONCLUSION

Our results demonstrate that in SSc fibroblasts, c-Abl is an upstream regulator of the profibrotic PKCδ/phospho-Fli-1 pathway, via induction of PKCδ nuclear localization. Additionally, the finding that Fli-1 is phosphorylated at higher levels in SSc fibroblasts supports the notion that the c-Abl/PKCδ/phospho-Fli-1 pathway is constitutively activated in these cells. Thus, blocking the TGFβ/c-Abl/PKCδ/phospho-Fli-1 pathway could be an attractive alternative approach to therapy for scleroderma.

CCN2 is required for the TGF-β induced activation of Smad1-Erk1/2 signaling network

Connective tissue growth factor (CCN2) is a multifunctional matricellular protein, which is frequently overexpressed during organ fibrosis. CCN2 is a mediator of the pro-fibrotic effects of TGF-β in cultured cells, but the specific function of CCN2 in the fibrotic process has not been elucidated. In this study we characterized the CCN2-dependent signaling pathways that are required for the TGF-β induced fibrogenic response. By depleting endogenous CCN2 we show that CCN2 is indispensable for the TGF-β-induced phosphorylation of Smad1 and Erk1/2, but it is unnecessary for the activation of Smad3. TGF-β stimulation triggered formation of the CCN2/β₃ integrin protein complexes and activation of Src signaling. Furthermore, we demonstrated that signaling through the α_vβ₃ integrin receptor and Src was required for the TGF-β induced Smad1 phosphorylation. Recombinant CCN2 activated Src and Erk1/2 signaling, and induced phosphorylation of Fli1, but was unable to stimulate Smad1 or Smad3 phosphorylation. Additional experiments were performed to investigate the role of CCN2 in collagen production. Consistent with the previous studies, blockade of CCN2 abrogated TGF-β-induced collagen mRNA and protein levels. Recombinant CCN2 potently stimulated collagen mRNA levels and upregulated activity of the COL1A2 promoter, however CCN2 was a weak inducer of collagen protein levels. CCN2 stimulation of collagen was dose-dependent with the lower doses (<50 ng/ml) having a stimulatory effect and higher doses having an inhibitory effect on collagen gene expression. In conclusion, our study defines a novel CCN2/α_vβ₃ integrin/Src/Smad1 axis that contributes to the pro-fibrotic TGF-β signaling and suggests that blockade of this pathway may be beneficial for the treatment of fibrosis.

Platelet lysate modulates MMP-2 and MMP-9 expression, matrix deposition and cell-to-matrix adhesion in keratinocytes and fibroblasts

Cell-matrix interactions are an essential element of wound healing, while platelet derivatives are used in clinical settings for the treatment of chronic wounds. We used a platelet lysate (PL), which had been previously shown to accelerate in vitro the wounding of HaCaT keratinocytes and fibroblasts (J Cell Mol Med, 13, 2009, 2030; Br J Dermatol, 159, 2008, 537), to study the modulation of MMP-2 and MMP-9 collagenase expression, collagen type I and III production and syndecan-4 expression and rearrangement in these cells. Zymography and Western blot analyses showed that exposure to 20% (v/v) PL for 24 h induced an apparently ERK1/2- and p38-dependent, NF-kappaB-independent, translational upregulation of MMP-9 in HaCaT, while HaCaT MMP-2 and fibroblast collagenases were almost unaffected. The use of in-cell ELISA showed that PL induced an increase in the collagen III production of fibroblasts. In-cell ELISA and immunofluorescence microscopy revealed an increase in the expression of syndecan-4 and its rearrangement to form focal adhesions in both cell types after PL exposure. Taken together, data indicate that PL promotes keratinocyte epithelialization and regulates fibroblast matrix deposition, thus providing a molecular basis for the ability of this platelet derivative to heal severe and problematic wounds without leading to heavy scarring and keloid formation.