EGF-stimulated migration in ovarian cancer cells is associated with decreased internalization, increased surface expression, and increased shedding of the urokinase plasminogen activator receptor

Circulating levels of soluble urokinase plasminogen activator receptor predict outcome after resection of biliary tract cancer

Background & Aims

Surgical resection is the only potentially curative therapy for patients with biliary tract cancer (BTC), but 5-year survival rates after tumor resection have remained below 30%, corroborating the need for better stratification tools to identify the ideal surgical candidates. The soluble urokinase plasminogen activator receptor (suPAR) represents a mediator of inflammation and has been associated with distinct types of cancer. In this study, we evaluated a potential role of suPAR as a novel biomarker in patients undergoing BTC resection.

Methods

Tumor expression of uPAR was analyzed by immunohistochemistry in 108 BTC samples. Serum levels of suPAR were analyzed by ELISA in a training and validation cohort comprising a total of 117 patients with BTC and 76 healthy controls.

Results

High tumoral uPAR expression was associated with an adverse outcome after BTC resection. Accordingly, circulating levels of suPAR were significantly elevated in patients with BTC compared to healthy controls, as well as in patients with primary sclerosing cholangitis. Using a small training set, we established an optimal prognostic suPAR cut-off value of 3.72 ng/ml for patients with BTC. Importantly, preoperative suPAR serum levels above this cut-off value were associated with significantly impaired overall survival in both the training and validation cohort. Multivariate Cox-regression analysis including various clinicopathological parameters such as tumor stage, markers of inflammation and organ dysfunction, as well as tumor markers, revealed circulating suPAR levels as an independent prognostic marker following BTC resection. Finally, high preoperative suPAR levels were indicative of acute kidney injury after tumor resection.

Conclusion

Circulating suPAR represents a previously unrecognized biomarker in patients with resectable BTC, which might help to preoperatively identify the ideal candidates for liver surgery.

Lay summary

Surgical resection represents the only curative treatment option for patients with biliary tract cancer, but not all patients benefit to the same extent in terms of overall survival. Here, we provide evidence that serum levels of an inflammatory mediator (suPAR) are indicative of a patient's postoperative outcome and might thus help to identify the ideal surgical candidates.

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Biliary tract cancer is associated with poor outcomes and increasing incidence.

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Surgical resection is the only potentially curative treatment option for patients with biliary tract cancer.

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The identification of ideal surgical candidates has remained challenging.

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Circulating suPAR represents a novel diagnostic and prognostic biomarker in resectable patients.

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SuPAR might be useful to identify patients with biliary tract cancer who will benefit most from tumor resection.

Peroxiporins in Cancer

The transport of H₂O₂ across membranes by specific aquaporins (AQPs) has been considered the last milestone in the timeline of hydrogen peroxide discoveries in biochemistry. According to its concentration and localization, H₂O₂ can be dangerous or acts as a signaling molecule in various cellular processes as either a paracrine (intercellular) and/or an autocrine (intracellular) signal. In this review, we investigate and critically examine the available information on AQP isoforms able to facilitate H₂O₂ across biological membranes (“peroxiporins”), focusing in particular on their role in cancer. Moreover, the ability of natural compounds to modulate expression and/or activity of peroxiporins is schematically reported and discussed.

Vitronectin in the ascites of human ovarian carcinoma acts as a potent chemoattractant for ovarian carcinoma: Implication for metastasis by cancer stem cells

Vitronectin has been identified mainly as an adhesion protein that signals through uPAR and selected integrin receptors. In addition to its pro-adhesive properties, we identified recently vitronectin as a main chemoattractant present in diluted plasma/serum that directly stimulates migration of cancer cells. We also found that this pro-migratory activity of vitronectin can be quenched by fibrinogen. Based on this we hypothesized that this may explain preference of cancer cell to metastasize to fibrinogen-low microenvironments such as lymphatics or peritoneal cavity. Based on this, we decided to investigate a role of vitronectin in metastasis of ovarian cancer cells to peritoneal cavity. We tested migratory responsiveness of three human ovarian cancer cell lines to ascites isolated from ovarian cancer patients and characterize possible molecules involved in migration of ovarian cancer cells. The ascites samples were exposed to heat inactivation, proteinase K digested, dialyzed and charcoal stripped. We also performed cut-off filtration analysis and by employing ELISA assays to measure concentration of vitronectin in ascites fluid samples. Finally, we employed shRNA against uPAR and small molecular inhibitors of integrin receptors to assess their involvement in biological effects of vitronectin. From our studies, we found that the similarly to diluted plasma, vitronectin in absence of fibrinogen is a main chemotactic/chemokinetic protein present in ascites fluid. We also found that these pro-migratory properties of vitronectin can be quenched by addition of fibrinogen. Our studies also indicate that both uPAR and integrin receptors on ovarian cancer cells regulate migration of these cells to vitronectin gradient. In summary, we identified free soluble vitronectin as a potent direct chemoattractant for ovarian cancer cells and that its activity is suppressed after binding to fibrinogen. Since in ascites fluids vitronectin is present in free form because of a lack or low level of fibrinogen, this could explain preferences of ovarian cancer stem cells to metastasize within peritoneum. We propose that inhibitors which could sequester soluble vitronectin in similar fashion as fibrinogen, could be employed as a novel anti-metastatic drugs.

Epidermal growth factor: Porcine uterine luminal epithelial cell migratory signal during the peri-implantation period of pregnancy

The majority of early conceptus mortality in pregnancy occurs during the peri-implantation period, suggesting that this period is important for conceptus viability and the establishment of pregnancy. Successful establishment of pregnancy in all mammalian species depends on the orchestrated molecular events that transpire at the conceptus-uterine interface during the peri-implantation period of pregnancy. This maternal-conceptus interaction is especially crucial in pigs because they have a non-invasive epitheliochorial placentation during a protracted peri-implantation period. During the pre-implantation period of pregnancy, conceptus survival and the establishment of pregnancy depend on the developing conceptus receiving an adequate supply of histotroph which contains a wide range of nutrients and growth factors. Evidence links epidermal growth factor (EGF) to embryogenesis or implantation in various mammalian species. EGF exhibits potential growth-promoting activities on the conceptus and endometrium; however, in the case of pigs, little is known its functions, especially their regulatory mechanisms at the maternal-conceptus interface. EGF receptor (EGFR) mRNA and protein are abundant in endometrial luminal (LE) and glandular (GE) epithelia and conceptus trophectoderm on Days 13-14 of pregnancy, suggesting that EGF provides an autocrine signal to uterine LE and GE just prior to implantation. Therefore, the objectives of this study were to determine: 1) the potential intracellular signaling pathways responsible for the activities of EGF in porcine uterine LE (pLE) cells; and 2) the changes in cellular activities induced by EGF. EGF treatment of pLE cells increased the abundance of phosphorylated (p)-ERK1/2, p-P70RSK and p-RPS6 compared to that for control cells. Furthermore, EGF-stimulated phosphorylation of ERK1/2 MAPK was inhibited in pLE cells transfected with an EGFR siRNA compared with control siRNA-transfected pLE cells. Moreover, EGF stimulated migration of pLE cells, but this stimulatory effect was blocked by U0126, a pharmacological inhibitor or ERK1/2 MAPK. Collectively, these results provide new insights into mechanisms whereby EGF regulates development of the peri-implantation uterine LE at the fetal-maternal interface. These results indicate that endometrial- and/or conceptus derived EGF effects migration of uterine LE and that those stimulatory effects are regulated via the ERK1/2 MAPK pathway during early pregnancy in pigs.

Intact and cleaved plasma soluble urokinase receptor in patients with metastatic colorectal cancer treated with oxaliplatin with or without cetuximab

Circulating forms of the urokinase plasminogen activator receptor (uPAR) are associated with prognosis in patients with colorectal cancer. Preclinical studies have shown that uPAR can influence the state of phosphorylation and signalling activity of the epidermal growth factor receptor (EGFR) in a ligand-independent manner. The purpose of the study was to evaluate whether plasma soluble intact and cleaved uPAR(I-III)+(II-III) levels could identify a subpopulation of patients with metastatic colorectal cancer (mCRC) where treatment with cetuximab would have a beneficial effect. Plasma samples were available from 453 patients treated in the NORDIC VII study. Patients were randomized between FLOX and FLOX + cetuximab. The levels of uPAR(I-III)+(II-III) were determined by time-resolved fluorescence immunoassay. We demonstrated that higher baseline plasma uPAR(I-III)+(II-III) levels were significantly associated with shorter progression-free survival (PFS) (HR = 1.30, 1.14-1.48, p = 0.0001) and overall survival (OS) (HR = 1.75, 1.52-2.02, p < 0.0001). Multivariate Cox analysis showed that plasma uPAR(I-III)+(II-III) was an independent biomarker of short OS (HR = 1.45, 1.20-1.75, p = 0.0001). There were no significant interactions between plasma uPAR(I-III)+(II-III) levels, KRAS mutational status and treatment either PFS (p = 0.43) or OS (p = 0.095). However, further explorative analyses indicated that patients with low levels of circulating suPAR and a KRAS wild-type tumor have improved effect from treatment with FLOX + cetuximab as compared to patients with KRAS wild-type and high levels of suPAR. These results thus support the preclinical findings and should be further tested in an independent clinical data set.

Tumour microenvironments induce expression of urokinase plasminogen activator receptor (uPAR) and concomitant activation of gelatinolytic enzymes

Background

The urokinase plasminogen activator receptor (uPAR) is associated with poor prognosis in oral squamous cell carcinoma (OSCC), and increased expression of uPAR is often found at the invasive tumour front. The aim of the current study was to elucidate the role of uPAR in invasion and metastasis of OSCC, and the effects of various tumour microenvironments in these processes. Furthermore, we wanted to study whether the cells’ expression level of uPAR affected the activity of gelatinolytic enzymes.

Methods

The Plaur gene was both overexpressed and knocked-down in the murine OSCC cell line AT84. Tongue and skin tumours were established in syngeneic mice, and cells were also studied in an ex vivo leiomyoma invasion model. Soluble factors derived from leiomyoma tissue, as well as purified extracellular matrix (ECM) proteins, were assessed for their ability to affect uPAR expression, glycosylation and cleavage. Activity of gelatinolytic enzymes in the tissues were assessed by in situ zymography.

Results

We found that increased levels of uPAR did not induce tumour invasion or metastasis. However, cells expressing low endogenous levels of uPAR in vitro up-regulated uPAR expression both in tongue, skin and leiomyoma tissue. Various ECM proteins had no effect on uPAR expression, while soluble factors originating from the leiomyoma tissue increased both the expression and glycosylation of uPAR, and possibly also affected the proteolytic processing of uPAR. Tumours with high levels of uPAR, as well as cells invading leiomyoma tissue with up-regulated uPAR expression, all displayed enhanced activity of gelatinolytic enzymes.

Conclusions

Although high levels of uPAR are not sufficient to induce invasion and metastasis, the activity of gelatinolytic enzymes was increased. Furthermore, several tumour microenvironments have the capacity to induce up-regulation of uPAR expression, and soluble factors in the tumour microenvironment may have an important role in the regulation of posttranslational modification of uPAR.

Cell Surface-Bound Plasminogen Regulates Hepatocyte Proliferation Through a uPA-Dependent Mechanism

Plasminogen and plasminogen activators play important roles in liver regeneration. Previously, we found that plasminogen potentiates hepatocyte proliferation in the primary culture of rat hepatocytes. Here, we examined how exogenous plasminogen affects the downstream events leading to cell proliferation. The addition of plasminogen to hepatocytes increased urokinase-type plasminogen activator (uPA) activity, but did not affect matrix metalloproteinase (MMP)-9 or MMP-2 activities. To increase uPA activity, plasminogen was required to bind the hepatocyte surface through the lysine-binding site of plasminogen molecule, but neither uPA mRNA nor uPA receptor (uPAR) mRNA was affected by the exogenous plasminogen. In addition, treatment of hepatocytes with an uPA inhibitor, p-aminobenzamidine, inhibited the plasminogen-induced and even EGF-induced hepatocyte proliferation. These results suggest that plasminogen-related control of hepatocyte proliferation is exerted topically by producing a hyperfibrinolytic state on the cellular surface involving the activation of uPA.

GEP100 regulates epidermal growth factor-induced MDA-MB-231 breast cancer cell invasion through the activation of Arf6/ERK/uPAR signaling pathway

GEP100, a guanine nucleotide exchanging factor (GEF) for Arf6, plays a pivotal role in promoting breast cancer cell invasion both in vitro and in vivo. However, the precise mechanism for GEP100-mediated cell invasion is still poorly understood. In this study, we found that down-regulation of endogenous GEP100 in MDA-MB-231 cells significantly inhibited EGF-induced cell invasion, which was rescued by over-expression of ectopic GEP100. EGF increased Arf6 activity, ERK phosphorylation, and uPAR expression in a time dependent manner. Additionally, blocking Arf6 with Arf6 siRNA largely abolished EGF-induced cell invasion. GEP100 siRNA or Arf6 siRNA suppressed EGF-induced ERK activity and uPAR expression. Furthermore, blocking ERK signaling with U0126, a specific inhibitor for MEK, markedly inhibited EGF-induced uPAR expression and consequently cell invasion. Inhibition of uPAR expression by uPAR siRNA also significantly abolished EGF-induced cell invasion. Taken together, this study illustrates that GEP100 regulates an Arf6/ERK/uPAR signaling cascade in EGF-induced breast cancer cell invasion. These findings could provide a rationale for designing new therapies based on inhibition of breast cancer metastasis.

EGFR/HER-targeted therapeutics in ovarian cancer

Despite decades of research and evolving treatment modalities, survival among patients with epithelial ovarian cancer has improved only incrementally. During this same period, the development of biologically targeted therapeutics has improved survival for patients with diverse malignancies. Many of these new drugs target the human epidermal growth factor receptor (EGFR/HER/ErbB) family of tyrosine kinases, which play a major role in the etiology and progression of many carcinomas, including epithelial ovarian cancer. While several HER-targeted therapeutics are US FDA approved for the treatment of various malignancies, none have gained approval for the treatment of ovarian cancer. Here, we review the published literature on HER-targeted therapeutics for the treatment of ovarian cancer, including novel HER-targeted therapeutics in various stages of clinical development, as well as the challenges that have limited the use of these inhibitors in clinical settings.

Prognosis in adenocarcinomas of lower oesophagus, gastro-oesophageal junction and cardia evaluated by uPAR-immunohistochemistry

Adenocarcinomas of lower oesophagus, gastro-oesophageal junction and cardia in humans are highly invasive tumours with poor prognosis. The localisation of urokinase-type plasminogen activator receptor (uPAR) was determined in 66 patients; 60 with adenocarcinomas and six cases with Barrett's oesophagus. uPAR was expressed in nearly all cases of invasive adenocarcinomas by populations of cancer cells, macrophages and myofibroblasts at both the invasion front and the tumour core. In areas with high-grade dysplasia or with Barrett's metaplasia adjacent to the tumour tissue, no uPAR-immunoreactivity was found. High local expression of uPAR, therefore, appears to be a characteristic marker for invasive behaviour in this tumour, suggesting that uPAR's contribution to matrix degradation during invasive growth is a late event in carcinogenesis. Using a scoring system for semiquantitative estimation of uPAR-positivity on immmunohistochemically stained specimens, a significant association was found between poor overall survival and high uPAR-score for cancer cells in the tumour core and for macrophages peripherally at the tumour invasion zone. In multivariate analysis, these two uPAR-scores were confirmed as highly significant prognostic parameters independent of Tumour, Node, Metastasis (TNM)-stage and World Health Organization (WHO) classification. The proteolytic action of these malignant and nonmalignant accessory cells thus seemed to follow two main patterns: one dominated by uPAR positive cancer cells and one by uPAR-positive macrophages. Scoring of uPAR-positivity might be a useful parameter for onset of invasion and prognosis in these adenocarcinomas.

Cysteine peptidases and their inhibitors in breast and genital cancer

Cysteine proteinases and their inhibitors probably play the main role in carcinogenesis and metastasis. The metastasis process need external proteolytic activities that pass several barriers which are membranous structures of the connective tissue which includes, the basement membrane of blood vessels. Activities of the proteinases are regulated by endogenous inhibitors and activators. The imbalance between cysteine proteinases and cystatins seems to be associated with an increase in metastatic potential in some tumors. It has also been reported that proteinase inhibitors, specific antibodies for these enzymes and inhibition of the urokinase receptor may prevent cancer cell invasion. Some proteinase inhibitor could serve as agents for cancer treatment.

Modulators of the urokinase-type plasminogen activation system for cancer

IMPORTANCE OF THE FIELD

The serine protease urokinase-type plasminogen activator (uPA) and its receptor uPAR as well as two specific inhibitors, the plasminogen activator inhibitor type-1 (PAI-1) and type-2 (PAI-2), are involved in the control of extracellular matrix turnover and tumor growth. Data accumulating over the past 20 years have made increasingly clear that the uPA system has a multifunctional role in neoplastic evolution, affecting cancer cell proliferation, tumor angiogenesis, adhesion and migration.

AREAS COVERED IN THIS REVIEW

Several therapeutic strategies inhibiting the uPA system have been or are currently being developed for suppression of tumor growth. This review examines the role of the uPA system in tumor progression and assesses the various therapeutic strategies developed to selectively exploit this system.

WHAT WILL THE READER GAIN

We focus on the therapeutic developments of the last 15 years. In addition to antibodies and recombinant uPA- or uPAR-derived proteins, various antagonistic peptides as well as small molecules have been designed and synthesized that inhibit the uPA system, leading to reduced tumor progression.

TAKE HOME MESSAGE

The multifunctional potential of the uPA system in cancer has rendered this system an attractive novel target for anticancer therapy. A few novel tumor biology-based therapeutic strategies reported here, opening new ways for patient-optimized and individualized cancer therapy. It may be the right time to evaluate the hypothesis that the uPA system plays a pivotal role in cancer progression and that targeting this system will lead to clinical benefit in cancer patients.

A cleavage-resistant urokinase plasminogen activator receptor exhibits dysregulated cell-surface clearance

Urokinase plasminogen activator receptor (u-PAR) binds urokinase plasminogen activator (u-PA) and participates in plasminogen activation in addition to modulating several cellular processes such as adhesion, proliferation, and migration. u-PAR is susceptible to proteolysis by its cognate ligand and several other proteases. To elucidate the biological significance of receptor cleavage by u-PA, we engineered and expressed a two-chain urokinase plasminogen activator (tcu-PA) cleavage-resistant u-PAR (cr-u-PAR). This mutated receptor was similar to wild-type u-PAR in binding u-PA and initiating plasminogen activation. However, cr-u-PAR exhibited accelerated internalization and resurfacing due to direct association with the endocytic receptor alpha(2)-macroglobulin receptor/low density lipoprotein receptor-related protein in the absence of the enzyme x inhibitor complex of tcu-PA and plasminogen activator inhibitor-1 (tcu-PA.PAI-1). cr-u-PAR-expressing cells had enhanced migration compared with wild-type u-PAR-expressing cells, and cr-u-PAR was less sensitive to chymotrypsin cleavage as compared with wt u-PAR. Our studies suggest that these mutations in the linker region result in a rearrangement within the cr-u-PAR structure that makes it resemble its ligand-bound form. This constitutively active variant may mimic highly glycosylated cleavage-resistant u-PAR expressed in certain highly malignant cancer-cells.

Epidermal growth factor stimulates human trophoblast cell migration through Rho A and Rho C activation

This study investigated the roles of Rho protein in epidermal growth factor (EGF)-induced trophoblast cell migration and its mechanism. Using choriocarcinoma cell lines JEG-3 and JAR and first-trimester human chorionic villus explant cultures on matrigel, we examined EGF-mediated stimulation of trophoblast migration. EGF is shown to have a dose-dependent effect on trophoblast migration. A low concentration of EGF (1 ng/ml) has a stimulatory effect on cell migration, whereas high concentrations of EGF (100 ng/ml) shows an inhibitory effect. EGF (1 ng/ml) activates RhoA and RhoC, but not RhoB, through elevated protein levels and activity. EGF-induced migration was shown to be inhibited by either cell-permeable C3 exoenzyme transferase or selective RhoA or RhoC small interfering RNAs. The inhibition was not mitigated by the addition of EGF, suggesting that RhoA and RhoC play an important role in trophoblast migration and are obligatory for EGF action. Treatment of JEG-3 and JAR cells with RhoA small interfering RNA induced F-actin cytoskeleton disruption and cell shrinkage, which is consistent with the effect of C3 exoenzyme transferase, and this action was not mitigated by EGF treatment. RhoC small interfering RNA had no apparent effect on the F-actin arrangement, suggesting that RhoA but not RhoC takes part in the EGF-induced migration through F-actin rearrangement. These results indicate that RhoA and RhoC play more important roles than RhoB in EGF-mediated migration of trophoblast cells, and RhoA but not RhoC regulates this migration through F-actin cytoskeleton reorganization.

Targeting the epidermal growth factor receptor in epithelial ovarian cancer: current knowledge and future challenges

The epidermal growth factor receptor is overexpressed in up to 60% of ovarian epithelial malignancies. EGFR regulates complex cellular events due to the large number of ligands, dimerization partners, and diverse signaling pathways engaged. In ovarian cancer, EGFR activation is associated with increased malignant tumor phenotype and poorer patient outcome. However, unlike some other EGFR-positive solid tumors, treatment of ovarian tumors with anti-EGFR agents has induced minimal response. While the amount of information regarding EGFR-mediated signaling is considerable, current data provides little insight for the lack of efficacy of anti-EGFR agents in ovarian cancer. More comprehensive, systematic, and well-defined approaches are needed to dissect the roles that EGFR plays in the complex signaling processes in ovarian cancer as well as to identify biomarkers that can accurately predict sensitivity toward EGFR-targeted therapeutic agents. This new knowledge could facilitate the development of rational combinatorial therapies to sensitize tumor cells toward EGFR-targeted therapies.

Ovarian cancer cells stimulate uPA gene expression in fibroblastic stromal cells via multiple paracrine and autocrine mechanisms

OBJECTIVES

Expression of uPA mRNA is massively up-regulated in the stroma of poorly differentiated ovarian tumors. We hypothesized that this expression was induced by paracrine signals from the epithelial tumor cells, and established an in vitro model of ovarian cancer microenvironment to study intercellular cross-talk.

METHODS

ES-2 clear cell carcinoma cells were grown in tissue culture inserts in a double-chamber system with fibroblastic stromal LEP cells embedded in Matrigel. Binding-site directed antibodies were used to neutralize soluble cytokines in ES-2 conditioned medium (CM) before incubation with LEP cells. Real time PCR measured uPA mRNA in LEP cells, as well as mRNA for cytokines in both cell types.

RESULTS

Co-culture with ES-2 cells as well as incubation with ES-2 CM induced uPA mRNA in LEP cells about two-fold. In short time (12 h) incubation of LEP cells with CM, antibodies to EGF and bFGF reduced induction of uPA mRNA, suggesting that these cytokines function as paracrine signals. EGF mRNA and bFGF mRNA were also found in ES-2 cells. At longer incubation (24 h) antibodies to bFGF, HB-EGF, HGF, IGF-1, and IL-1alpha reduced uPA mRNA induction, suggesting an autocrine function for these cytokines in LEP cells. In fact, expression of the same five cytokines was up-regulated in LEP cells exposed to CM.

CONCLUSION

We identified two cytokines as paracrine signals, and five cytokines as autocrine signals in ovarian cancer cell induced up-regulation of uPA mRNA in stromal fibroblastic cells. It is crucial to understand intra-tumoral cross-talk, since it can offer new therapeutic approaches.

Adhesion and migration of ovarian cancer cells on crosslinked laminin fibers nanofabricated by multiphoton excited photochemistry

Ovarian cancer is the deadliest gynecological cancer, which may arise in part due to the concurrent invasion and metastasis of high grade tumors. It is thus crucial to gain insight into the adhesion and migration mechanisms in vivo, as this may ultimately lead to new treatment/detection options. To explore this possibility, we have used multiphoton excited photochemistry (MPE) to synthesize models of the ovarian basal lamina consisting of crosslinked laminin nanofibers to quantify the adhesion/migration dynamics. The nanostructured laminin patterns permit the systematic comparison of total migration, directed migration, adhesion, and morphology of "normal" immortalized human ovarian epithelial cells (IOSE) and three lines of varying metastatic potential (OVCA433, SKOV-3.ip1, and HEY-1 cells). We find that the migration of all the cell lines is directed by the crosslinked fibers, and that the contact guidance enhances the total migration rates relative to monolayers. These rates increase with increasing metastatic potential, and the more invasive cells are less rigid and more weakly adhered to the nanofibers. The extent of directed migration also depends on the cell polarity and focal adhesion expression. For the invasive cells, these findings are similar to the integrin-independent ameboid-like migration seen for polar cells in collagen gels. Collectively, the results suggest that contact mediated migration as well as decreased adhesion may be operative in metastasis of ovarian cancer in vivo.

Estradiol attenuates EGF-induced rapid uPAR mobilization and cell migration via the G-protein-coupled receptor 30 in ovarian cancer cells

Epidermal growth factor (EGF) stimulates proliferation and migration in ovarian cancer cells, and high tumor expression of the EGF system correlates with poor prognosis. Epidermal growth factor upregulates urokinase plasminogen activator receptor (uPAR) on the cell surface via 3 distinct mechanisms: rapid mobilization of uPAR from detergent-resistant domains, increased mRNA, and decreased degradation. G-protein-coupled receptor 30 (GPR30) is a newly identified membrane estrogen receptor (ER).The objective of this study was to explore the effects of 17beta-estradiol (E(2)) on uPAR expression and cell migration in ovarian cancer cells and further to identify the ER involved.We used 7 ovarian cancer cell lines, cell migration assay, cellular binding of (125)I-uPA, cellular degradation of (125)I-uPA/PAI-1 complex, enzyme-linked immunosorbent assay for uPAR, solid-phase enzyme immunoassay for ERalpha, and quantitative polymerase chain reaction. Estradiol attenuates the stimulatory effect of EGF on cell migration and uPAR expression. Specifically, E(2) reduces the very rapid increase of detergent extractable uPAR, which occurs within minutes of EGF stimulation and probably represents mobilization of uPAR from detergent-resistant domains such as lipid rafts. Estradiol influenced neither the amount of uPAR mRNA nor the rate of uPAR degradation or solubilization. The nuclear ER antagonists ICI 182780 and tamoxifen, which are GPR30 agonists, as well as the specifically constructed GPR30 agonist G1, mimicked the effect of E(2) on uPAR expression and cell migration. OVCAR-3 cells express mRNA for GPR30.Estradiol attenuates EGF-induced mobilization of ligated uPAR from detergent-resistant domains and subsequent migration in ovarian cancer cells. The response to various ER ligands indicates that this effect is mediated via the membrane ER GPR30.

Cleaved forms of the urokinase plasminogen activator receptor in plasma have diagnostic potential and predict postoperative survival in patients with ovarian cancer

PURPOSE

To evaluate the plasma level of different forms of soluble urokinase plasminogen activator receptor (suPAR) as discriminators between malignant, borderline, and benign ovarian tumors and as prognostic markers in patients with ovarian cancer.

EXPERIMENTAL DESIGN

The different suPAR forms were measured in preoperative plasma samples obtained from 335 patients with adnexal lesions using three different time-resolved fluoresence assays (TR-FIA): TR-FIA 1 measuring intact suPAR, suPAR(I-III), TR-FIA 2 measuring the total amount of suPAR(I-III) and the cleaved form, suPAR(II-III), and TR-FIA 3 measuring the liberated uPAR(I). Tumors were classified as benign (n = 211), borderline (possibly malignant; n = 30), and well (n = 19), moderately (n = 15), and poorly (n = 60) differentiated malignant.

RESULTS

All uPAR forms as well as CA125 were statistically significant in univariate analysis discriminating between benign, borderline, and invasive tumors. Restricting the analysis of invasive tumors to early stage (I and II) showed similar results. A combination of CA125 and suPAR(I-III) + suPAR(II-III) discriminated between malignant (all stages) and benign tumors [AUC, 0.94; 95% confidence interval (95% CI), 0.90-0.98] as well as borderline and benign tumors (AUC, 0.78; 95% CI, 0.67-0.89). All suPAR forms were markers for poor prognosis in univariate analyses, and high preoperative plasma level of uPAR(I) is an independent predictor of poor prognosis (hazard ratio, 1.84; 95% CI, 1.15-2.95; P = 0.011) in multivariate analyses including age and CA125.

CONCLUSIONS

High concentration of plasma uPAR(I) is an independent preoperative marker of poor prognosis in patients with ovarian cancer. The combination of plasma suPAR(I-III) + suPAR(II-III) and CA125 discriminates between malignant and benign tumors with an AUC of 0.94.

Curcumin attenuates EGF-induced AQP3 up-regulation and cell migration in human ovarian cancer cells

OBJECTIVE

Aquaporin (AQP) water channels are expressed in high-grade tumor cells of different tissue origins. Based on the involvement of AQPs in angiogenesis and cell migration as well as our previous studies which show that AQP3 is involved in human skin fibroblasts cell migration, in this study, we investigated whether AQP3 is expressed in cultured human ovarian cancer cell line CaOV3 cells, and whether AQP3 expression in these cells enhances cell migration and metastatic potential.

METHODS

Cultured CaOV3 cells were treated with EGF and/or various reagents and subjected to cell migration assay by phagokinetic track mobility assay or biochemical analysis for expression or activation of proteins by SDS-PAGE/Western blot analysis.

RESULTS

In this study, we demonstrate that AQP3 is expressed in CaOV3 cells. EGF induces CaOV3 migration and up-regulates AQP3 expression. EGF-induced cell migration is inhibited by specific AQP3 siRNA knockdown or AQP3 water transport inhibitor CuSO4 and NiCl2. We also find that curcumin, a well known anti-ovarian cancer drug, down-regulates AQP3 expression and reduces cell migration in CaOV3, and the effects of curcumin are mediated, at least in part, by its inhibitory effects on EGFR and downstream AKT/ERK activation.

CONCLUSIONS

Collectively, our results provide evidence for AQP3-facilitated ovarian cancer cell migration, suggesting a novel function for AQP3 expression in high-grade tumors. The results that curcumin inhibits EGF-induced up-regulation of AQP3 and cell migration, provide a new explanation for the anticancer potential of curcumin.

Synergistic effects of epidermal growth factor and hepatocyte growth factor on human ovarian cancer cell invasion and migration: role of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase

Ovarian cancer is the primary cause of death from gynecological malignancies with a poor prognosis characterized by widespread peritoneal dissemination. However, mechanisms of invasion and metastasis in ovarian cancer remain poorly understood. Epidermal growth factor (EGF) and hepatocyte growth factor (HGF) are often both overexpressed and contribute to the growth of ovarian cancer by activating autocrine pathways. In the present study, we investigated the mechanisms of invasive activity of EGF, HGF, and their synergistic effects in human ovarian cancer cells. Here our data suggest that EGF and HGF may use unique and overlapping signaling cascades leading to the invasive phenotype. We revealed that HGF-mediated cell migration and invasion required the coordinate activation of the phosphatidylinositol 3-kinase/Akt and extracellular signal-regulated kinase 1/2. Although EGF-dependent invasive phenotype appeared to have similar requirements for phosphatidylinositol 3-kinase, this growth factor used the alternative p38 MAPK pathway for cell invasion. A significant role of p38 MAPK was further supported by the observation that expression of dominant negative p38 MAPK likewise inhibited EGF-dependent invasiveness and cell motility. We also showed that EGF cooperated with HGF to promote a highly invasive phenotype via the increased secretion of matrix metalloproteinase (MMP)-9. The coincident induction of MMP-9 was functionally significant because inclusion of MMP-9 inhibitor or an anti-MMP-9 neutralizing antibody abolished EGF- and HGF-induced cellular invasion. These findings provide insights into the mechanism of the malignant progression of ovarian cancer.