TGF-β1 Axis Research Articles

Extracellular vesicle-derived LINC00482 induces microglial M2 polarization to facilitate brain metastasis of NSCLC

Considering the crucial role of long non-coding RNAs (lncRNAs) in non-small cell lung cancer (NSCLC), we tried to analyze the role of extracellular vesicle (EV)-derived LINC00482 in the occurrence of brain metastasis in NSCLC. LINC00482 expression was quantified in EVs isolated from serum samples of NSCLC patients (serum-EVs). Ectopic expression and depletion assays were conducted in the microglial cell line HMC3 co-cultured with serum-EVs and in xenograft mouse models of NSCLC to explore the roles of EV-carried LINC00482. LINC00482 was enriched in serum-EVs and induced M2 polarization of microglial cells HMC3 in vitro. LINC00482 competitively bound to miR-142-3p and upregulated the expression of miR-142-3p target gene TGF-β1 in HMC3 cells, thus promoting microglial M2 polarization. EV-derived LINC00482-induced M2 microglia promoted the malignant properties of NSCLC cells. In vivo data demonstrated that EVs transmitted LINC00482 to regulate the miR-142-3p/TGF-β1 axis, induce microglial M2 polarization and affect the pre-metastatic niche, thus enhancing brain metastasis of NSCLC. Overall, suppression of the expression of tumor-derived LINC00482 or LINC00482-containing EVs, may serve as an effective target for contributing to the reduction of brain metastasis of NSCLC.

Regorafenib enhances anti-tumor efficacy of immune checkpoint inhibitor by regulating IFN-γ/NSDHL/SREBP1/TGF-β1 axis in hepatocellular carcinoma

Immune checkpoint inhibitor (ICI) shows low response rate in hepatocellular carcinoma (HCC) but the mechanisms underlying ICI resistance remains unclear. Interferon-γ (IFN-γ) has been widely determined as a prototypical antitumor cytokine. However, growing studies suggest that IFN-γ also mediates immunosuppression to promote tumor progression. Herein, we explored whether ICI-induced IFN-γ could activate immunosuppressive TGF-β1 to mediate ICI resistance. We demonstrated that cholesterol biosynthetic enzyme, NSDHL, was decreased in HCC tissues and associated with poor clinical prognosis. ICI-induced IFN-γ decreased NSDHL to activate SREBP1, which promoted TGF-β1 production, reduced T cell toxicity and enhanced Tregs infiltration, leading to ICI resistance. We also found that novel tyrosine kinase inhibitor, regorafenib, significantly reverse the above immunosuppressive effects by regulating NSDHL/SREBP1/TGF-β1 axis, which strengthened the effects of regorafenib plus ICI therapy against HCC. Noteworthily, regorafenib plus ICI therapy was more effective in HCC patients with higher serum TGF-β1. In conclusion, IFN-γ induced TGF-β1 to mediate ICI resistance. Regorafenib promotes anti-tumor immune response of ICI by regulating IFN-γ/NSDHL/SREBP1/TGF-β1 axis. Serum TGF-β1 may serve as a biomarker for predicting efficacy of regorafenib plus ICI therapy in HCC.

β2-Microglobulin Maintains Glioblastoma Stem Cells and Induces M2-like Polarization of Tumor-Associated Macrophages

β2-microglobulin signaling in glioblastoma cells activates a PI3K/AKT/MYC/TGFβ1 axis that maintains stem cells and induces M2-like macrophage polarization, highlighting potential therapeutic strategies for targeting tumor cells and the immunosuppressive microenvironment in glioblastoma.

LncRNA TUG1 Regulates Proliferation of Cardiac Fibroblast via the miR-29b-3p/TGF-β1 Axis.

Background: Atrial fibrillation (AF) is a very common clinical arrhythmia, accompanied by the overproliferation of cardiac fibroblasts (CFs). This study aimed to investigate the role of the long non-coding RNA(lncRNA) taurine upregulated gene 1 (TUG1) in the proliferation of CFs and further investigated its underlying mechanism.Methods: One hundred four paroxysmal AF patients and 94 healthy controls were recruited. Human cardiac fibroblasts (HCFs) were applied to establish an AF cell model through treatment with angiotensin II (AngII). qRT-PCR was used for the measurement of gene levels. The cell proliferation was detected by cell counting kit-8 (CCK-8). Luciferase reporter assay was performed for target gene analysis.Results: Elevated levels of TUG1 and low expression of miR-29b-3p were detected in the serum of AF patients compared with the healthy controls. Pearson's correlation analysis exhibited an inverse relationship between TUG1 and miR-29b-3p expression in AF patients (r = −7.106, p < 0.001). Knockdown of TUG1 inhibited AngII-induced CF proliferation. Taurine upregulated gene 1 (TUG1) functions as a competing endogenous RNA (ceRNA) for miR-29b-3p, and downregulation of miR-29b-3p reversed the role of TUG1 in CF proliferation. TGF-β1 is a direct target gene of miR-29b-3p.Conclusions: Long non-coding RNA taurine upregulated gene 1 is a key regulator in the occurrence of AF. Slicing TUG1 inhibits CF proliferation by regulating the miR-29b-3p/TGF-β1 axis.

Interleukin-18 promotes the antitumor ability of natural killer cells in colorectal cancer via the miR-574-3p/TGF-β1 axis

ABSTRACT Interleukin (IL)-18 has a clear antitumor effect; however, its mechanisms of action are not understood in patients with colorectal cancer (CRC). Here, we investigated the potential mechanism of IL-18 in CRC. The results showed that IL-18 treatment alone had no effect on HCT116 cells apoptosis, whereas IL-18 in the presence of natural killer (NK) cells resulted in apoptosis and inhibition of cells proliferation in vitro. Profiling of miRNA expression following coculture with NK cells and treatment with IL-18 resulted in significant downregulation of miR-574-3p expression and upregulated expression of the target gene transforming growth factor beta 1 (TGF-β1). miR-574-3p binds to TGF-β1, and miR-574-3p overexpression increased the proliferation and decreased the apoptotic rate of HCT116 cells in NK cells coculture with IL-18 treatment; overexpression of TGF-β1 restored the effect of miR-574-3p overexpression. The miRNA profile of HCT116 undergoes significant alteration before and after coculturing with NK cells and treatment with IL-18. IL-18 alone did not affect HCT116 cells apoptosis but did promote the antitumor ability of NK cells in coculture with HCT116 cells via the miR-574-3p/TGF-β1 axis. Our study suggested that IL-18 can be a new potential target for cancer immunotherapy for CRC.

MiR-130a/TGF-β1 axis is involved in sow fertility by controlling granulosa cell apoptosis

TGF-β1 is a ligand of the TGF-β superfamily and an important cytokine that regulates ovarian functions including follicular development, steroid production, ovulation, luteinization, and female fertility. However, little is known about the regulation of TGF-β1 expression in ovary. Here, we identified that TGF-β1 is a functional target of miR-130a in porcine ovarian granulosa cells (GCs). The 3′-UTR sequence of TGF-β1 gene (1137 bp in length) in Large White (LW) pig was isolated, and multiple RNA regulatory elements (RREs), including several binding motifs of different miRNAs, were identified in this region. Luciferase activity assay showed that miR-130a dramatically suppresses the 3′-UTR luciferase activity of TGF-β1 gene, and further inhibits the expression of TGF-β1 in porcine GCs. FACS revealed that miR-130a acts as a pro-apoptotic factor and promotes GC apoptosis by inhibiting TGF-β1. Two novel linked mutations (−573G > A and −540T > C) were identified in the promoter region of ssc-miR-130a, but their polymorphisms are not associated with sow reproductive traits. Importantly, combined genotype analysis with a known mutation (c.1583 A > G) in the 3′-UTR of porcine TGF-β1 gene showed a significant association with reproductive performance in LW sow population. Overall, our findings defined a novel regulatory axis, miR-130a/TGF-β1 axis, which is involved in regulating sow fertility.

Metformin inhibits extracellular matrix accumulation, inflammation and proliferation of mesangial cells in diabetic nephropathy by regulating H19/miR-143-3p/TGF-β1 axis.

Metformin (MET) has protective effect on diabetic nephropathy (DN). This study aims to demystify the mechanism of MET function in DN. Mouse glomerular membrane epithelial cell line SV40-MES-13 was treated with normal or high glucose combined with or without MET. The relationships among H19, miR-143-3p and TGF-β1 were evaluated by luciferase reporter assay. MTT assay was performed to detect cell proliferation. The levels of inflammatory factors were investigated by enzyme-linked immunosorbent assay. Quantitative real-time PCR and western blot were performed to examine gene and protein expression. H19 was up-regulated in the SV40-MES-13 cells after treated with high glucose, which was effectively repressed by MET treatment. MET promoted extracellular matrix accumulation, inflammation and proliferation in the SV40-MES-13 cells after treated with high glucose. These influences conferred by MET were abolished by H19 overexpression. H19 regulated TGF-β1 expression by sponging miR-143-3p. Furthermore, MET inhibited extracellular matrix accumulation, inflammation and proliferation by regulating H19/miR-143-3p/TGF-β1 axis. Our studies demonstrated that the protective effect of MET on DN was attributed to the inhibition of proliferation, inflammation and ECM accumulation in mesangial cells via H19/miR-143-3p/TGF-β1 axis, which suggested that the H19/miR-143-3p/TGF-β1 axis could be a valuable target for DN therapies.

The Prognostic Impact of Leucine-Rich α-2-Glycoprotein-1 in Cholangiocarcinoma and Its Association With the IL-6/TGF-β1 Axis

BackgroundLeucine-rich α-2-glycoprotein-1 (LRG) has been found to participate in the development of various cancers through its involvement in TGF-β1-induced epithelial-mesenchymal transition (EMT) and/or angiogenesis and can be induced by inflammatory cytokines, such as IL-6. As we previously showed the implication of IL-6/TGF-β axis in EMT of cholangiocarcinoma cells, we herein explored the prognostic impact of LRG in postoperative intrahepatic cholangiocarcinoma (ICC) and assessed the association between tumor LRG and factors such as TGF-β1, IL-6, and the tumor microvessel density. MethodsWe determined the expression of LRG, IL-6, TGF-β1, and CD31 in cancer tissues from 50 ICC patients by immunohistochemistry and analyzed their association with the prognosis. ResultsThe LRG expression was closely associated with recurrence-free survival (RFS) and overall survival (OS) in postoperative ICC. A multivariate Cox regression model indicated that LRG as an independently associated with poor RFS (hazard ratio = 2.4339, P = 0.0354) and OS (hazard ratio = 2.8892, P = 0.0268). The LRG expression was significantly associated with the expression of TGF-β1 (P = 0.0003) and IL-6 (P = 0.0164). ConclusionsThe upregulation of LRG in tumors was an independent prognostic factor in patients with postoperative ICC. LRG was closely associated with the TGF-β1 expression and seems to be an important member of the IL-6/TGF-β1 axis.

LncRNA MIR4435-2HG-mediated upregulation of TGF-β1 promotes migration and proliferation of nonsmall cell lung cancer cells.

The roles of long noncoding RNAs (lncRNAs) have been shown to play critical roles in tumor progression. Here, it was identified that lncRNA MIR4435-2HG was highly expressed in lung cancer tissues, especially in nonsmall cell lung cancer (NSCLC). A consistent result was obtained in lung cancer cells. Functional experiments showed that knockdown of MIR4435-2HG reduced the proliferation and migration ability of NSCLC cells. Transcriptome-sequencing analysis indicated that TGF-β signaling was mostly enriched in NSCLC cells with MIR4435-2HG knockdown. Furthermore, MIR4435-2HG was identified as an miRNA sponge for TGF-β1 and thus activated TGF-β signaling. Additionally, re-activation of TGF-β1 rescued MIR4435-2HG knockdown-mediated inhibition on the progression of NSCLC cells. Therefore, this work indicates a novel MIR4435-2HG/TGF-β1 axis responsible for NSCLC cell progression.

HIF1A/miR-20a-5p/TGFβ1 axis modulates adipose-derived stem cells in a paracrine manner to affect the angiogenesis of human dermal microvascular endothelial cells.

Angiogenic cytokines secreted by the adipose-derived stem cells (ADSCs) might promote the angiogenesis of endothelial cells. In the present study, we hypothesize that miR-20a targets TGFB1 to modulate the transforming growth factor β1 (TGFβ1) secretion by ADSCs, therefore affecting the angiogenesis. We found that hypoxia-inducible factor 1A (HIF1A) and TGFβ1 expressions were increased by hypoxia, accompanied with promoted ADSC cell viability. Incubation with conditioned medium from ADSCs treated with hypoxia significantly enhanced the angiogenesis capacity of human dermal microvascular endothelial cells (HDMECs), while TGFB1-silenced ADSCs medium significantly reverses HDMECs angiogenesis. miR-20a suppresses the expression of TGFB1 and secretion of TGFβ1 by ADSCs via binding to its 3'untranslated region, therefore modulating the HDMEC angiogenesis via affecting the paracrine from ADSCs; the effects of miR-20a-overexpressed conditioned medium on HDMEC angiogenesis were significantly reversed by TGFB1-overexpressed conditioned medium. Finally, HIF1A suppressed the expression of miR-20a via targeting its promoter region, subsequently promoting the paracrine from ADSCs and HDMEC angiogenesis.

Pericytes Elicit Resistance to Vemurafenib and Sorafenib Therapy in Thyroid Carcinoma via the TSP-1/TGFβ1 Axis.

The BRAFV600E oncogene modulates the papillary thyroid carcinoma (PTC) microenvironment, in which pericytes are critical regulators of tyrosine-kinase (TK)-dependent signaling pathways. Although BRAFV600E and TK inhibitors are available, their efficacy as bimodal therapeutic agents in BRAFV600E-PTC is still unknown. We assessed the effects of vemurafenib (BRAFV600E inhibitor) and sorafenib (TKI) as single agents or in combination in BRAFWT/V600E-PTC and BRAFWT/WT cells using cell-autonomous, pericyte coculture, and an orthotopic mouse model. We also used BRAFWT/V600E-PTC and BRAFWT/WT-PTC clinical samples to identify differentially expressed genes fundamental to tumor microenvironment. Combined therapy blocks tumor cell proliferation, increases cell death, and decreases motility via BRAFV600E inhibition in thyroid tumor cells in vitro. Vemurafenib produces cytostatic effects in orthotopic tumors, whereas combined therapy (likely reflecting sorafenib activity) generates biological fluctuations with tumor inhibition alternating with tumor growth. We demonstrate that pericytes secrete TSP-1 and TGFβ1, and induce the rebound of pERK1/2, pAKT and pSMAD3 levels to overcome the inhibitory effects of the targeted therapy in PTC cells. This leads to increased BRAFV600E-PTC cell survival and cell death refractoriness. We find that BRAFWT/V600E-PTC clinical samples are enriched in pericytes, and TSP1 and TGFβ1 expression evoke gene-regulatory networks and pathways (TGFβ signaling, metastasis, tumor growth, tumor microenvironment/ECM remodeling functions, inflammation, VEGF ligand-VEGF receptor interactions, immune modulation, etc.) in the microenvironment essential for BRAFWT/V600E-PTC cell survival. Critically, antagonism of the TSP-1/TGFβ1 axis reduces tumor cell growth and overcomes drug resistance. Pericytes shield BRAFV600E-PTC cells from targeted therapy via TSP-1 and TGFβ1, suggesting this axis as a new therapeutic target for overcoming resistance to BRAFV600E and TK inhibitors.

NEAT1 induces osteosarcoma development by modulating the miR-339-5p/TGF-β1 pathway.

The long noncoding RNA (lncRNA) nuclear enriched abundant transcript 1 (NEAT1) has been recognized as a tumor oncogene involved in the development of multiple cancers. However, the function of NEAT1 and its molecular mechanism in osteosarcoma (OS) remain unclear. First, we detected the NEAT1 expression in OS cell lines by performing quantitative reverse-transcription polymerase chain reaction. Next, the effects of NEAT1 on OS cell growth, apoptosis, migration, and invasion were tested by lentivirus-mediated downregulation. We observed that inhibition of NEAT1 restrained OS cell progression greatly. Interestingly, in the last few years, increasing studies have shown that some lncRNAs can act as miRNA sponges and reduce the amount of the same. Here, we found that NEAT1 can modulate OS development via sponging miR-339-5p. MiR-339-5p was significantly decreased in OS cells, and its overexpression can remarkably repress the OS proliferation. These results indicated that NEAT1 could function as a tumor oncogene in OS by inhibiting miR-339-5p in vitro. Then, the following assays validated that transforming growth factor β1 (TGF-β1) can act as a functional target of miR-339-5p in OS cells. Finally, we indicated that NEAT1 could mediate TGF-β1 expression by competitively sponging miR-339-5p. NEAT1 induced OS cell proliferation and cell mobility by binding to miR-339-5p and increasing TGF-β1 in OS. It was demonstrated in our study that lncRNA NEAT1 could impede miR-339-5p expression to maintain the expression of TGF-β1, which led to the development of OS. Our findings implied that the novel identified NEAT1/miR-339-5p/TGF-β1 axis might be a new molecular pathway or therapeutic target for OS diagnosis and treatment.

NEAT1 upregulates TGF-β1 to induce hepatocellular carcinoma progression by sponging hsa-mir-139-5p.

Increasing evidence has shown that the lncRNA Nuclear Enriched Abundant Transcript 1 (NEAT1) play important roles in cell proliferation, migration, and invasion in various tumors. In our current study, we concentrated on the biological mechanisms of NEAT1 in hepatocellular carcinoma (HCC) development. It was found that NEAT1 was significantly increased in human HCC cell lines including Hep3B, LM3, MHCC97L, SK-hep1, and HepG2 cells compared to the normal human liver cell line LO2. Meanwhile, we observed that hsa-miR-139-5p was greatly decreased in HCC cells, which suggested a negative correlation between NEAT1 and hsa-mir-139-5p. In addition, NEAT1 downregulation can restrain HCC cell growth, migration, and invasion. Consistently, overexpression of hsa-mir-139-5p exerted a similar phenomenon. Dual-luciferase reporter assay, RIP assay, and RNA pull-down assay confirmed that NEAT1 can function as a ceRNA by sponging hsa-mir-139-5p. In addition, TGF-β1 was identified as a downstream target of hsa-mir-139-5p and hsa-mir-139-5p overexpression was able to suppress TGF-β1 levels. Furthermore, it was indicated that TGF-β1 inhibition can inhibit HCC cell growth, migration, and invasion ability. Taken these together, we speculated that NEAT1 can modulate TGF-β1 expression by sponging hsa-mir-139-5p in HCC. These data indicates that targeting the NEAT1/hsa-mir-139-5p/TGF-β1 axis could be a new strategy for HCC.

XIST promotes gastric cancer (GC) progression through TGF-β1 via targeting miR-185.

LncRNAs and microRNAs can play significant roles in various cancers, including gastric cancer (GC). In our study, we investigated the role of lncRNA XIST in GC. We observed that XIST was increased in MGC803 and BGC823 cells compared to human normal gastric epithelial GES-1 cells. It was also shown that miR-185 was decreased in GC cell lines. Silencing XIST can inhibit the growth of GC cells and bioinformatics analysis was performed to confirm the correlation between XIST and miR-185. Interestingly, a negative correlation was indicated between XIST and miR-185 in GC cells. In addition, TGF-β1 was predicted as a target gene of miR-185. miR-185 can modulate TGF-β1 expression negatively in vitro. Moreover, we found that sh-XIST inhibited GC development via decreasing TGF-β1 by upregulating miR-185 in vitro. Therefore, we speculated that XIST can act as a competing endogenous lncRNA (ceRNA) to regulate TGF-β1 by sponging miR-185 in GC. Taken these together, it was indicated that XIST/miR-185/TGF-β1 axis participated in the development of GC. XIST could act as a potential prognostic biomarker in GC development.

Abstract 4449: Thrombospondin-1 regulation by MDM2 in aggressive cancers

Abstract MDM2 amplification, which is often seen in different cancer types, indicates that its plays an important role in tumorigenesis and also in cancer metastasis. Amplification of the MDM2 gene correlates with poor prognosis, aggressive growth, and reoccurrence. Thrombospondin-1 (TSP-1) that is expressed by THBS1 gene is a matricellular protein, and is known to have differential expression in cancers. When TSP-1 activates Transforming Growth Factor-β1 (TGF-β1) through latent cytokine complexation, the activated TGF-β1 contributes to the Epithelial to Mesenchymal Transition (EMT) which is known to impart stem-cell like characteristics and drug resistance to the cancer cells. However, no studies regarding MDM2’s role in THBS1 regulation have been carried out so far. Therefore, the objective of this study was to determine the correlation between MDM2 and THBS1 expression in MDM2 overexpressing cancers. For this purpose the SJSA-1 osteosarcoma cells were cultured at 37 oC under humidified air/CO2 (19:1) in RPMI-1640 complete medium supplemented with 10% FBS, 10,000 U/mL penicillin, 10,000 µg/mL streptomycin, 1% (+)-L-glutamine, and 1% amphotericin B. The cells were incubated in the presence of 20 µM of Nutlin-3 for 24 hrs, following which, RNA and protein were extracted and subsequently purity and concentration were determined. Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) and western blotting were performed using specific primers, primary and the secondary antibodies respectively. Interestingly elevated levels of TSP-1 and TGFβ1 were observed in these SJSA-1 cells. However, after treatment with Nutlin-3, an MDM2-p53 interaction inhibitor, a significant increase in p53 was noted. However, contrary to the existing literature, where studies have shown p53 to positively regulate TSP-1 levels, we observed an opposite outcome. Despite the Nutlin-3 induced elevation in p53 levels, a significant decrease in TSP-1 level was observed indicating that MDM2 may be regulating THBS1 gene expression in a p53 independent manner, in MDM2 overexpressing SJSA-1 cells. The findings of this study suggest a novel, p53 independent role for MDM2 in THBS1 regulation. Since MDM2 amplification can positively induce TSP-1 levels, which is one of the natural activators of TGF-β1, it is anticipated that stimulatory signal flowing through MDM2 - TSP-1 - TGF-β1 axis may induce the cancer cells to undergo EMT, thereby increasing their metastatic ability and promote cancer stem cell characteristics. This novel MDM2-regulated pathway can very well serve as a drug target and might play a biologically relevant role in the treatment of cancer metastasis. Our future studies will include validation of this correlation in multiple cancer cell lines, to further elucidate the mechanism through which MDM2 is regulating THBS1 gene expression. (This project was supported by The Royal Dames of Cancer Research Inc., Ft. Lauderdale, Florida). Citation Format: Priya Dondapati, Jason Maragh, Karna Mangrola, Ali Alaseem, Khadija Cheema, Thiagarajan Venkatesan, Sivanesan Dhandayuthapani, Appu Rathinavelu. Thrombospondin-1 regulation by MDM2 in aggressive cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4449. doi:10.1158/1538-7445.AM2017-4449

Calcitriol ameliorates renal damage in a pre-established proteinuria model.

Proteinuria is critical in the tubulointerstitial changes that ultimately lead to renal insufficiency. Increased protein filtration has direct toxic effects on tubular epithelial cells, leading to epithelial mesenchymal transition (EMT) to a myofibroblast phenotype. Angiotensin II and transforming growth factor (TGF)-β1 are the main mediators of EMT. Calcitriol may exert a potential renoprotective effect by reducing the activity of the renin angiotensin system by suppressing renin gene expression and also by inhibiting the proinflammatory nuclear factor-κB pathway. The present study investigated the benefits of calcitriol treatment in a puromycin-induced protein-uric nephropathy model. Uninephrectomized adult male Wistar rats received intraperitoneal administration of a single dose of puromycin (100 mg/kg) or vehicle. After eight weeks, the animals were divided into two groups and received vehicle or calcitriol (0.5 μg/kg) for four weeks. The vehicle-treated, proteinuric rats developed progressive proteinuria and tubulointerstitial fibrosis after 12 weeks. Increased collagen deposition and fibrosis were significantly ameliorated by calcitriol treatment. Calcitriol was effective in preventing an increase in the EMT markers, α-smooth muscle actin and fibroblast-specific protein 1, reducing macrophage infiltration as evidenced by levels of ED-1. In addition, calcitriol increased the anti-inflammatory cytokine interleukin-10 and reduced the pro-oxidant p47 phox enzyme. These effects were paralleled by a reduction in TGF-β/Smad3 expression. Calcitriol may have therapeutic potential in the proteinuric nephropathy model used in the present study by inhibiting the TGF-β1 axis.

A pathogenetic role for endothelin-1 in peritoneal dialysis-associated fibrosis.

In patients undergoing peritoneal dialysis (PD), chronic exposure to nonphysiologic PD fluids elicits low-grade peritoneal inflammation, leading to fibrosis and angiogenesis. Phenotype conversion of mesothelial cells into myofibroblasts, the so-called mesothelial-to-mesenchymal transition (MMT), significantly contributes to the peritoneal dysfunction related to PD. A number of factors have been described to induce MMT in vitro and in vivo, of which TGF-β1 is probably the most important. The vasoconstrictor peptide endothelin-1 (ET-1) is a transcriptional target of TGF-β1 and mediates excessive scarring and fibrosis in several tissues. This work studied the contribution of ET-1 to the development of peritoneal damage and failure in a mouse model of PD. ET-1 and its receptors were expressed in the peritoneal membrane and upregulated on PD fluid exposure. Administration of an ET receptor antagonist, either bosentan or macitentan, markedly attenuated PD-induced MMT, fibrosis, angiogenesis, and peritoneal functional decline. Adenovirus-mediated overexpression of ET-1 induced MMT in human mesothelial cells in vitro and promoted the early cellular events associated with peritoneal dysfunction in vivo. Notably, TGF-β1-blocking peptides prevented these actions of ET-1. Furthermore, a positive reciprocal relationship was observed between ET-1 expression and TGF-β1 expression in human mesothelial cells. These results strongly support a role for an ET-1/TGF-β1 axis as an inducer of MMT and subsequent peritoneal damage and fibrosis, and they highlight ET-1 as a potential therapeutic target in the treatment of PD-associated dysfunction.

Synergism between fibronectin and transforming growth factor-β1 in the production of substance P in monocytes of patients with myelofibrosis

Substance P (SP), also considered a proinflammatory cytokine, as well as others such as transforming growth factor-β1 (TGF-β1) and interleukin-1 (IL-1), and the extracellular matrix protein fibronectin (FN) have been associated with the pathophysiology of myelofibrosis. SP is encoded by the TAC1 gene. The relationships among SP, TGF-β1, IL-1 and FN are poorly understood. This study determined the mechanisms for concomitant production of IL-1, TGF-β1 and SP and also determined the synergistic role of FN in SP release. Enzyme-linked immunosorbent assay (ELISA) indicated increased levels of SP and TGF-β1 in the blood of patients with myelofibrosis. Monocytes, shown to be activated in patients with bone marrow (BM) fibrosis, expressed the TAC1 gene for SP release, in a nuclear factor-κB (NFκB)-dependent manner. Reporter gene assay with the 5’ regulatory region of TAC1 indicated its expression by high levels of FN and TGF-β1. Immunohistochemical studies of paraffin-embedded BM biopsies from patients with myelofibrosis, and age-matched controls without fibrosis, indicated co-localization of SP and its receptor neurokinin-1 (NK1). In summary, myelofibrotic monocytes have autocrine loops that stimulate the release of SP and TGF-β1, and that are potentiated by fibronectin. The FN-mediated induction of SP in turn stimulates monocytes through autostimulation by NK1 receptors. These findings, combined with those of previous studies, demonstrate an adhesion-mediated NFκB/IL-1/TGF-β1 axis that can be initiated by increased FN in patients with myelofibrosis for the production of SP. These findings show how TGF-β1 and SP production are coupled, and suggest new therapeutic targets to reverse immune-mediated fibrosis.

Adenosine mediates transforming growth factor-beta 1 release in kidney glomeruli of diabetic rats

Up regulation of the transforming growth factor-beta 1 (TGF-β1) axis has been recognized as a pathogenic event for progression of glomerulosclerosis in diabetic nephropathy. We demonstrate that glomeruli isolated from diabetic rats accumulate up to sixfold more extracellular adenosine than normal rats. Both decreased nucleoside uptake activity by the equilibrative nucleoside transporter 1 and increased AMP hydrolysis contribute to raise extracellular adenosine. Ex vivo assays indicate that activation of the low affinity adenosine A 2B receptor subtype (A 2BAR) mediates TGF-β1 release from glomeruli of diabetic rats, a pathogenic event that could support progression of glomerulopathy when the bioavailability of adenosine is increased.

Diabetic complications: A role for the prorenin–(pro)renin receptor–TGF-β1 axis?

Morbidity and mortality of diabetes mellitus are strongly associated with cardiovascular disease including nephropathy. A discordant tissue renin-angiotensin system (RAS) might be a mediator of the endothelial dysfunction leading to both micro- and macrovascular complications of diabetes. The elevated plasma levels of prorenin in diabetic subjects with microvascular complications might be part of this discordant RAS, especially since the plasma renin levels in diabetes are low. Prorenin, previously thought of as an inactive precursor of renin, is now known to bind to a (pro)renin receptor, thus activating locally angiotensin-dependent and -independent pathways. In particular, the stimulation of the transforming growth factor-beta (TGF-beta) system by prorenin could be an important contributor to diabetic disease complications. This review discusses the concept of the prorenin-(pro)renin receptor-TGF-beta(1) axis, concluding that interference with this pathway might be a next logical step in the search for new therapeutic regimens to reduce diabetes-related morbidity and mortality.