Protease-Activated Receptor–Stimulated Interleukin-6 Expression in Endometriosis-Like Lesions in an Experimental Mouse Model of Endometriosis

Therapeutic Strategies Focused on Cancer-Associated Hypercoagulation for Ovarian Clear Cell Carcinoma

Ovarian clear cell carcinoma (OCCC) is associated with chemotherapy resistance and poor prognosis, especially in advanced cases. Although comprehensive genomic analyses have clarified the significance of genomic alterations such as ARID1A and PIK3CA mutations in OCCC, therapeutic strategies based on genomic alterations have not been confirmed. On the other hand, OCCC is clinically characterized by a high incidence of thromboembolism. Moreover, OCCC specifically shows high expression of tissue factor and interleukin-6, which play a critical role in cancer-associated hypercoagulation and may be induced by OCCC-specific genetic alterations or the endometriosis-related tumor microenvironment. In this review, we focused on the association between cancer-associated hypercoagulation and molecular biology in OCCC. Moreover, we reviewed the effectiveness of candidate drugs targeting hypercoagulation, such as tissue factor- or interleukin-6-targeting drugs, anti-inflammatory drugs, anti-hypoxia signaling drugs, anticoagulants, and combined immunotherapy with these drugs for OCCC. This review is expected to contribute to novel basic research and clinical trials for the prevention, early detection, and treatment of OCCC focused on hypercoagulation.

Toll-like receptor signaling pathway triggered by inhibition of serpin A1 stimulates production of inflammatory cytokines by endometrial stromal cells

Endometriosis is characterized by the presence of inflamed and fibrotic endometrial tissue outside the uterine cavity. Previously, we found decreased SERPINA1 (alpha-1 antitrypsin) expression in endometriosis-like lesions in a mouse model of endometriosis, suggesting that it exacerbated inflammation in these lesions. However, the molecular mechanism(s) by which SERPINA1 affects expression of inflammatory factors and development of endometriotic lesions have not been fully characterized. To investigate the role of intracellular SERPINA1 in endometrial stromal cells (ESCs), we performed RNA sequence analysis using RNA extracted from ESCs in which SERPINA1 was knocked down. The analysis identified several toll-like receptor (TLR)-related factors as being upregulated. Silencing of SERPINA1 increased expression of TLR3 and TLR4 in ESCs, as well as several TLR signaling pathway components, including MYD88, IRAK1/4, interleukin (IL)-1β, and interferon (IFN)-β. TLR3 or TLR4 agonists increased expression of inflammatory factors in SERPINA1-knockdown ESCs, whereas TLR3 or TLR4 inhibitors decreased expression. In addition, treatment with recombinant IL-1β or IFN-β increased expression of MYD88 and inflammatory factors in ESCs. Immunohistochemical analysis of endometriotic tissues showed that TLR3, TLR4, and MYD88 were localized in endometriosis lesions. Taken together, the data suggest that reduced expression of SERPINA1 induces expression of inflammatory factors by ESCs, which in turn are associated with TLR3/4, IL-1β, and IFN-β signaling. Regulation of intracellular SERPINA1 levels in ESCs may be a strategy to inhibit inflammatory responses in endometriotic lesions.

PGE2 and Thrombin Induce Myofibroblast Transdifferentiation via Activin A and CTGF in Endometrial Stromal Cells

Endometriosis is characterized by inflammation and fibrotic changes. Our previous study using a mouse model showed that proinflammatory factors present in peritoneal hemorrhage exacerbated inflammation in endometriosis-like grafts, at least in part through the activation of prostaglandin (PG) E2 receptor and protease-activated receptor (PAR). In addition, menstruation-related factors, PGE2 and thrombin (P/T), a PAR1 agonist induced epithelial-mesenchymal transition (EMT) of endometrial cells under hypoxia. However, the molecular mechanisms by which P/T induce development of endometriosis have not been fully characterized. To investigate the effects of P/T, RNA extracted from endometrial stromal cells (ESCs) treated with P/T were subjected to RNA sequence analysis, and identified activin A, FOS, and GATA2 as upregulated genes. Activin A increased the expression of connective tissue growth factor (CTGF) and mesenchymal marker genes in ESCs. CTGF induced the expression of fibrosis marker type I collagen, fibronectin, and α-smooth muscle actin (αSMA), indicating fibroblast to myofibroblast transdifferentiation (FMT) of ESCs. In addition, activin A, FOS, GATA2, CTGF, and αSMA were localized in endometriosis lesions. Taken together, our data show that P/T induces changes resembling EMT and FMT in ectopic ESCs derived from retrograde menstruation, and that these are associated with fibrotic changes in the lesions. Pharmacological means that block P/T-induced activin A and CTGF signaling may be strategies to inhibit fibrosis in endometriotic lesions.

Endometrial epithelial-mesenchymal transition (EMT) by menstruation-related inflammatory factors during hypoxia

Endometriosis is characterised by inflammation and fibrotic changes. Our previous study using a mouse model showed that proinflammatory factors present in peritoneal haemorrhage exacerbated inflammation in endometriosis-like grafts, at least in part through the activation of prostaglandin (PG) E2 receptor and protease-activated receptor (PAR). In addition, hypoxia is a well-known inducer of fibrosis that may be associated with epithelial-mesenchymal transition (EMT). However, the complex molecular interactions between hypoxia and proinflammatory menstruation-related factors, PGE2 and thrombin, a PAR1 agonist, on EMT in endometriosis have not been fully characterised. To explore the effects of hypoxia and proinflammatory factors on EMT-like changes in endometrial cells, we determined the effects of PGE2 and thrombin (P/T) on EMT marker expression and cell migration in three dimensional cultured human endometrial epithelial cells (EECs) and endometrial stromal cells (ESCs). Treatment of EECs with P/T under hypoxia stimulated cell migration, increased the expression of mesenchymal N-cadherin, vimentin and C-X-C chemokine receptor type 4 (CXCR4), and reduced the expression of epithelial E-cadherin. Furthermore, treatment with C-X-C motif chemokine ligand 12 (CXCL12), a ligand for CXCR4, increased EMT marker expression and cell migration. In ESCs, P/T or oestrogen treatment under hypoxic conditions increased the expression and secretion of CXCL12. Taken together, our data show that hypoxic and proinflammatory stimuli induce EMT, cell migration and inflammation in EECs, which was increased by CXCL12 derived from ESCs. These data imply that inflammatory mediators in retrograde menstrual fluid contribute to ectopic endometrial EMT and migration in the presence of peritoneal hypoxia.

Glibenclamide inhibits NLRP3 inflammasome-mediated IL-1β secretion in human trophoblasts

Infection-associated pregnancy complications cause premature delivery. Caspase-1 is involved in the maturation of interleukin (IL)-1β, which is activated by the NLRP3 inflammasome. To characterize the significance of the NLRP3 inflammasome pathway in the placenta, the effects of activators and inhibitors on NLRP3-related molecules were examined using isolated primary trophoblasts. Caspase-1 and IL-1β mRNA expression was markedly increased in response to lipopolysaccharide (LPS), a toll-like receptor (TLR)4 ligand. Treatment with the potassium ionophore nigericin significantly increased the level of activated caspase-1. Treatment with either LPS or nigericin stimulated IL-1β secretion, whereas pretreatment with the ATP-sensitive K⁺ channel inhibitor glibenclamide, the Rho-associated coiled-coil kinase inhibitor Y-27632, or a caspase-1 inhibitor significantly decreased nigericin-induced IL-1β secretion. In addition, dibutyryl-cAMP, which induces trophoblast differentiation, decreased expression of NLRP3, caspase-1, and IL-1β. These findings suggest that trophoblasts can secrete IL-1β through the NLRP3/caspase-1 pathway, which is suppressed by glibenclamide, and that the TLR4-mediated NLRP3 inflammasome pathway is more likely to be stimulated in undifferentiated than differentiated trophoblasts. Our data support the hypothesis that inhibition of the NLRP3 inflammasome can suppress placental inflammation-associated disorders.

Protease-activated receptors in kidney disease progression

Protease-activated receptors (PARs) are members of a well-known family of transmembrane G protein-coupled receptors (GPCRs). Four PARs have been identified to date, of which PAR1 and PAR2 are the most abundant receptors, and have been shown to be expressed in the kidney vascular and tubular cells. PAR signaling is mediated by an N-terminus tethered ligand that can be unmasked by serine protease cleavage. The receptors are activated by endogenous serine proteases, such as thrombin (acts on PARs 1, 3, and 4) and trypsin (PAR2). PARs can be involved in glomerular, microvascular, and inflammatory regulation of renal function in both normal and pathological conditions. As an example, it was shown that human glomerular epithelial and mesangial cells express PARs, and these receptors are involved in the pathogenesis of crescentic glomerulonephritis, glomerular fibrin deposition, and macrophage infiltration. Activation of these receptors in the kidney also modulates renal hemodynamics and glomerular filtration rate. Clinical studies further demonstrated that the concentration of urinary thrombin is associated with glomerulonephritis and type 2 diabetic nephropathy; thus, molecular and functional mechanisms of PARs activation can be directly involved in renal disease progression. We briefly discuss here the recent literature related to activation of PAR signaling in glomeruli and the kidney in general and provide some examples of PAR1 signaling in glomeruli podocytes.

Tissue Factor-Factor VII Complex As a Key Regulator of Ovarian Cancer Phenotypes

Tissue factor (TF) is an integral membrane protein widely expressed in normal human cells. Blood coagulation factor VII (fVII) is a key enzyme in the extrinsic coagulation cascade that is predominantly secreted by hepatocytes and released into the bloodstream. The TF–fVII complex is aberrantly expressed on the surface of cancer cells, including ovarian cancer cells. This procoagulant complex can initiate intracellular signaling mechanisms, resulting in malignant phenotypes. Cancer tissues are chronically exposed to hypoxia. TF and fVII can be induced in response to hypoxia in ovarian cancer cells at the gene expression level, leading to the autonomous production of the TF–fVII complex. Here, we discuss the roles of the TF–fVII complex in the induction of malignant phenotypes in ovarian cancer cells. The hypoxic nature of ovarian cancer tissues and the roles of TF expression in endometriosis are discussed. Arguments will be extended to potential strategies to treat ovarian cancers based on our current knowledge of TF–fVII function.

Integrative Analysis Reveals Regulatory Programs in Endometriosis

Endometriosis is a common gynecological disease found in approximately 10% of reproductive-age women. Gene expression analysis has been performed to explore alterations in gene expression associated with endometriosis; however, the underlying transcription factors (TFs) governing such expression changes have not been investigated in a systematic way. In this study, we propose a method to integrate gene expression with TF binding data and protein-protein interactions to construct an integrated regulatory network (IRN) for endometriosis. The IRN has shown that the most regulated gene in endometriosis is RUNX1, which is targeted by 14 of 26 TFs also involved in endometriosis. Using 2 published cohorts, GSE7305 (Hover, n = 20) and GSE7307 (Roth, n = 36) from the Gene Expression Omnibus database, we identified a network of TFs, which bind to target genes that are differentially expressed in endometriosis. Enrichment analysis based on the hypergeometric distribution allowed us to predict the TFs involved in endometriosis (n = 40). This included known TFs such as androgen receptor (AR) and critical factors in the pathology of endometriosis, estrogen receptor α, and estrogen receptor β. We also identified several new ones from which we selected FOXA2 and TFAP2C, and their regulation was confirmed by quantitative real-time polymerase chain reaction and immunohistochemistry (IHC). Further, our analysis revealed that the function of AR and p53 in endometriosis is regulated by posttranscriptional changes and not by differential gene expression. Our integrative analysis provides new insights into the regulatory programs involved in endometriosis.

Possible Role of α1-Antitrypsin in Endometriosis-Like Grafts From a Mouse Model of Endometriosis

Previous study indicated that bleeding into the peritoneum may accelerate inflammatory response in endometriosis-like grafts in mice. To identify changes in protein levels in the grafts from mice that underwent unilateral ovariectomy (uOVX), which causes bleeding from ovarian arteries and vein, the grafts were generated by injecting a suspension of human endometrial cells in BALB/c nude female mice, and protein profile changes were compared with non-uOVX control mice. The level of α1-antitrypsin (α1-AT) decreased in grafts from nude mice that underwent uOVX. The levels of phosphorylated Akt, mammalian target of rapamycin, S6K, regulatory factors for cell survival, and of phosphorylated nuclear factor κB, an inflammatory mediator, were higher in endometriosis-like grafts from the uOVX group than from the control. The grafts were mostly comprised of stromal cells. The bioactivity of α1-AT was assessed by investigating cytokine expression in protease-activated receptor (PAR) 1/2 agonists-stimulated stromal cells. The PARs promoted the expression of interleukin 8 (IL-8), but treatment with α1-AT blocked IL-8 expression dose dependently. Knocking down α1-AT expression increased the constitutive IL-6, IL-8, and cyclooxygenase 2 expression as well as PAR1 agonist-stimulated IL-6 expression. These findings support the notion that decreased α1-AT protein in the grafts constituted with human endometrial cells in mice may have exacerbated inflammation in endometriosis-like grafts, suggesting the possible involvement of α1-AT in the pathophysiology of endometriosis.

ENMD-1068, a protease-activated receptor 2 antagonist, inhibits the development of endometriosis in a mouse model

OBJECTIVE

Protease-activated receptor 2 plays an important role in the pathogenesis of endometriosis. We studied the effect of ENMD-1068, a protease-activated receptor 2 antagonist, on the development of endometriosis in a noninvasive fluorescent mouse model.

STUDY DESIGN

A red fluorescent protein-expressing xenograft model of human endometriosis was created in nude mice. After endometriosis induction, the mice were injected intraperitoneally with either 25 mg/kg or 50 mg/kg ENMD-1068 or with 200 μL of the vehicle control daily for 5 days. The endometriotic lesions that developed in the mice were then counted, measured, and collected. The lesions were assessed for the production of interleukin 6 and monocyte chemotactic protein-1 by enzyme-linked immunosorbent assays and evaluated for the activation of nuclear factor-κB and the expression of vascular endothelial growth factor by immunohistochemical analyses. Cell proliferation and apoptosis were assessed by immunohistochemistry for Ki-67 and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, respectively.

RESULTS

ENMD-1068 dose-dependently inhibited the development of endometriotic lesions (P < .05) without apparent toxicity to various organs of the treated mice. Consistently, ENMD-1068 dose-dependently inhibited the expression of interleukin 6 and nuclear factor-κB (P < .05) and cell proliferation (P < .05) in the lesions, as well as increased the percentage of apoptotic cells (P < .05). ENMD-1068 reduced the levels of monocyte chemotactic protein-1 and vascular endothelial growth factor in the lesions (P < .05), but not in a dose-dependent manner.

CONCLUSION

Our study suggests that ENMD-1068 is effective in suppressing the growth of endometriosis, which might be attributed to the drug's antiangiogenic and antiinflammatory activities.