The plasminogen-activation system in ovarian tumors

Si113-prodrugs selectively activated by plasmin against hepatocellular and ovarian carcinoma

Si113, a pyrazolo[3,4-d]pyrimidine derivative, gained more attention as an anticancer agent due to its potent anticancer activity on both in vitro and in vivo hepatocellular carcinomas (HCC) and ovarian carcinoma models. But the drawback is the low water solubility which prevents its further development. In this context, we successfully overcame this limitation by synthesizing two novel prodrugs introducing the amino acid sequence D-Ala-Leu-Lys (TP). Moreover, TP sequence has a high affinity with plasmin, a protease recognized as overexpressed in many solid cancers, including HCC and ovarian carcinoma. The prodrugs were synthesized and fully characterized in terms of in vitro ADME properties, plasma stability and plasmin-induced release of the parent drug. The inhibitory activity against Sgk1 was evaluated and in vitro growth inhibition was evaluated on ovarian carcinoma and HCC cell lines in the presence and absence of human plasmin. In vivo pharmacokinetic properties and preliminary tissue distribution confirmed a better profile highlighting the importance of the prodrug approach. Finally, the prodrug antitumor efficacy was evaluated in an HCC xenografted murine model, where a significant reduction (around 90%) in tumor growth was observed. Treatment with ProSi113-TP in combination with paclitaxel in a paclitaxel-resistant ovarian carcinoma xenografted murine model, resulted in an impressive reduction of tumor volume greater than 95%. Our results revealed a promising activity of Si113 prodrugs and pave the way for their further development against resistant cancer.

High tumor tissue concentration of urokinase plasminogen activator receptor is associated with good prognosis in patients with ovarian cancer

The urokinase plasminogen activator (uPA) system is involved in tumor growth and metastasis. We assayed the components of the uPA system in homogenates of 64 primary epithelial ovarian tumors and 5 metastases and evaluated the association of these parameters to prognosis in the 51 malignant cases. The levels of uPA, PAI-2 and the uPA:PAI-1 complex increased with progressive loss of histological differentiation (p(trend) <0.001, <0.05 and <0.001). The level of PAI-1 was higher in poorly than in well/moderately differentiated tumors (p = 0.03). The content of uPAR was lower in benign tumors as compared to borderline malignancies (p = 0.002), invasive primary tumors (p < 0.001), and metastases (p = 0.002). Surprisingly, the level of uPAR was lower in poorly differentiated as compared to both borderline (p = 0.01) and well differentiated malignant tumors (p = 0.005). Also, the level of uPAR was lower in advanced as compared to early stages of the disease (p(trend) = 0.002). The median follow-up time for patients was 5.8 years. High tumor tissue levels of uPAR were associated with longer postoperative survival (HR = 0.4, 95% CI = 0.2-0.8, p = 0.01). In contrast, shorter survival was evident in patients with high tumor levels of uPA from 2 years on after operation (HR = 4.6, 95% CI = 1.2-17, p = 0.02). High tPA levels tended to be associated with shorter overall survival after 2 years (HR = 2.9, 95% 95% CI = 0.9-9.8, p = 0.08). Although high tumor tissue content of uPAR was associated with a less aggressive phenotype characterized by well differentiated histology and longer survival, low content of uPAR in the poorly differentiated tumors and metastases presumably results from increased elimination of uPAR.

Possible role of matriptase in the diagnosis of ovarian cancer

There are increasing data that suggest a role for the serine protease matriptase and its inhibitor, hepatocyte growth factor activator inhibitor-1, in the pathogenesis and progression of ovarian cancer. This review will discuss the matriptase/inhibitor system in the context of ovarian cancer and examine the possibility that this system might be a useful therapeutic and/or diagnostic target in this disease.

Alpha(v)beta(6) integrin-A marker for the malignant potential of epithelial ovarian cancer

The mechanism(s) responsible for the progression of non-metastatic or borderline ovarian cancer to invasive Grade I/III ovarian cancer is still unknown. An epithelium-restricted integrin, alpha(v)beta(6), is present in malignant epithelia but not in normal epithelia. We studied the relative expression and distribution of alpha(v)beta(6) integrin in early and late-stage invasive (Grade I and Grade III) and non-invasive (benign and borderline) ovarian tumors of serous, mucinous, endometrioid, and clear-cell carcinoma subtypes, to assess its potential as a marker for epithelial ovarian cancer progression. Sixty-six specimens, including eight normal, 13 benign, 14 borderline, 13 Grade I, and 18 Grade III tumors were evaluated by immunohistochemistry (IHC) using a monoclonal antibody (MAb) against alpha(v)beta(6) integrin. Normal ovarian surface epithelium was negative for alpha(v)beta(6) integrin expression. All 45 carcinomas studied were positive, and the staining intensity significantly correlated with the grade of the tumor. The Grade III carcinomas of all types showed strong staining intensity. Only mucinous benign tissues were positive, and no reactivity was observed in benign serous neoplasms. On the basis of these observations, we hypothesize that the expression of alpha(v)beta(6) integrin is associated with epithelial ovarian cancer and that a gradual increase in the expression of the molecule may be a correlative index of the progression of this disease.

Overexpression of alpha(v)beta6 integrin in serous epithelial ovarian cancer regulates extracellular matrix degradation via the plasminogen activation cascade

Recent evidence suggests that integrins are involved in the multi-step process of tumour metastasis. The biological relevance of alpha(v) integrins and associated beta-subunits in ovarian cancer metastasis was examined by analysing the expression of these cell surface receptors in nine ovarian cancer cell lines and also in the primary human ovarian surface epithelial cell line (HOSE). beta1, beta3 and beta5 subunits were present in all ten ovarian cell lines. beta6 subunit was present at varying levels in eight out of nine cancer cell lines but was absent in the HOSE cell line. Immunohistochemical staining showed that beta6 was present in both non-invasive (borderline) and high-grade ovarian cancer tissues but was absent in benign and normal ovarian tissue. High alpha(v)beta6 integrin expressing ovarian cancer cell lines had high cell surface expression of uPA and uPAR. Ovarian cancer cell lines expressing high to moderate level of alpha(v)beta6 integrin demonstrated ligand-independent enhanced levels of high molecular weight (HMW)-uPA and pro-matrix metalloproteinase 2 and 9 (pro-MMP-2 and pro-MMP-9) expression in the tumour-conditioned medium. High and moderate expression of alpha(v)beta6 integrin correlated with increased plasminogen-dependent degradation of extracellular matrix which could be inhibited by inhibitors of plasmin, uPA and MMPs or by monoclonal antibody against uPA, MMP-9 or alpha(v)beta6 integrin. These results suggest that endogenous de novo expression of alpha(v)beta6 integrin in ovarian cancer cells may contribute to their invasive potential, and that alpha(v)beta6 expression may play a role in ovarian cancer progression and metastasis.

High-dose progesterone inhibition of urokinase secretion and invasive activity by SKOV-3 ovarian carcinoma cells: evidence for a receptor-independent nongenomic effect on the plasma membrane

Urokinase plasminogen activator (uPA) has been implicated in the metastatic potential of ovarian carcinomas of surface epithelial origin. The SKOV-3 human ovarian cancer cell line was tested for uPA secretory responses (enzyme immunoassay of conditioned media) after treatments with sex steroids, human menopausal gonadotropins (hMG), or gonadotropin-releasing hormone (GnRH). Secretion of uPA during a 6-h incubation was unaffected by testosterone, estradiol-17beta, hMG, or GnRH. Progesterone, at supraphysiological concentrations, suppressed uPA secretion; this reaction was not altered by the progesterone receptor antagonist RU486 or the transcriptional inhibitor actinomycin D. It appears that progesterone exerted a direct biophysical effect on the plasma membrane manifested by an interference with shedding of uPA in exocytotic vesicles. Finally, invasion of SKOV-3 cells into Matrigel was inhibited by progesterone. We suggest that progesterone can disrupt the fluid dynamics of plasma membranes and thereby invoke an antitumorigenic action via inhibition of proteolytic secretions.

Expression of various matrix proteases and Ets family transcriptional factors in ovarian cancer cell lines: correlation to invasive potential

OBJECTIVES

The aim of our study was to determine the important molecules responsible for the invasive activity of ovarian cancer cells.

METHODS

We compared the biological characteristics, that is, growth rate, motility, and invasive activity, of five ovarian cancer cell lines with the gene expression of various matrix proteases (matrix metalloproteinase-1 [MMP-1], MMP-2, MMP-9, membrane-type MMP type 1 [MT1-MMP], MT2-MMP, MT3-MMP, urokinase plasminogen activator [uPA]), their inhibitors (tissue inhibitor of metalloproteinase type 1 [TIMP-1], TIMP-2, plasminogen activator inhibitor type 1, [PAI-1], and PAI-2), and the potential transcriptional regulators E1AF and Ets-1.

RESULTS

There was no clear correlation in the growth rate, motility, and invasion, suggesting that there are independent properties for malignant potential in ovarian cancer cells. However, HTBOA, a poorly differentiated cancer cell line, exhibited highly invasive activity, rapid growth, and increased motility. This cell line also expressed both Ets transcriptional factors, E1AF and Ets-1, and many matrix-degrading enzymes. Three cell lines that expressed E1AF showed rapid cell growth. The highly invasive cell lines, HTBOA and HTOA (well-differentiated serous cystadenocarcinoma), produced either MMP-2 or MMP-1, and both cell lines expressed MT1-MMP and uPA. Furthermore, the active forms of pro-MMP-2 and pro-MMP-1 were detected in HTBOA and HTOA by zymography.

CONCLUSION

We conclude that activated MMP-2 and MMP-1 are important in the invasive activity of these ovarian cancer cells.

Clinical relevance of urokinase-type plasminogen activator, its receptor and inhibitor type 1 in ovarian cancer

Urokinase-type plasminogen activator (uPA), its receptor (uPAR) and inhibitor, plasminogen activator-type 1 (PAI-1) are proposed to be of prognostic significance in some cancers. To determine the prognostic value of the urokinase plasminogen activation system in ovarian cancer, levels of uPA, uPAR, and PAI-1 were measured in extracts of ovarian cancer tissue using ELISA tests. uPA and PAI-1 were determined in 70 tumor extracts and uPAR in 43 extracts. Levels were correlated with age, tumor histology, stage, grade, lymph node and metastatic status, residual disease, risk of recurrence, epidermal growth factor receptor (EGFR) expression, cathepsin D (Cath-D), and c-erbB-2 levels. uPA and uPAR did not exhibit correlation with any of these parameters. However, patients with high grade tumor, recurrence, and lower EGFR and Cath-D had significantly higher PAI-1 levels compared to those of others (P < 0.05). Kaplan-Meier plots of survival were compared. uPA and uPAR were not related to disease-free or overall survival. Although low PAI-1 appeared to predict a longer overall survival, the difference was not statistically significant. Multivariate analysis revealed that PAI-1 was a predictor for overall survival although it was not as strong as stage. These results suggest that elevated PAI-1 seems to be correlated with an unfavorable prognosis in ovarian cancer.

Chemotherapy and thrombosis in gynecologic malignancy

Thromboembolism is a severe and frequent problem in gynecologic malignancy. The average DVT incidence during chemotherapy of 5% might represent the lower range of incidence because < 55% of thrombotic complication manifest clinical signs. However, it seems likely that in addition to chemotherapy other risk factors such as menopausal status, BMI of patients, or type of preceding surgery must coincide before thrombosis manifests. While monitoring of patients using sophisticated coagulation tests did not identify patients' risk for DVT during chemotherapy, an evaluation of the coagulation status before initiating chemotherapy is recommended. Patients with a venous access device (e.g., indwelling central venous catheter or with port cart) are at a particularly high risk for DVT. This has to be considered when cytoreductive therapy is given. Thrombosis prophylaxis, orally or subcutaneously, should only be considered in a subpopulation of patients who offer a combination of the aforementioned risk factors. Thrombosis prevention trials during chemotherapy found a significant reduction of DVT in patients treated with anticoagulants.

Prognostic significance of urokinase (uPA) and its inhibitor PAI-1 for survival in advanced ovarian carcinoma stage FIGO IIIc

Strong evidence has accumulated on the prognostic value of tumour-associated proteolytic factors in patients afflicted with solid malignant tumours, including advanced ovarian cancer. We evaluated the prognostic impact of the protease urokinase plasminogen activator (uPA) and its inhibitor PAI-1 on overall survival in patients with advanced ovarian cancer stage FIGO IIIc in order to select patients at risk. uPA and PAI-1 antigen were determined by ELISA in primary tumour tissue extracts of 86 ovarian cancer patients FIGO stage IIIc enrolled in a prospective study. Univariate and multivariate analyses were performed using the Cox proportional hazard model. The time-varying coefficient model of Gray was used to assess the time-dependent strength of prognostic factors tumour mass, uPA and PAI-1 on overall survival. In all patients, uPA and PAI-1 (optimized cut-offs of 2.0 and 27.5 ng mg(-1) protein respectively), in addition to the traditional prognostic parameters of residual tumour mass, nodal status, grading and ascites volume, were of prognostic significance in univariate analysis for overall survival. Even in patients with residual tumour mass (n = 43), the statistically independent prognostic impact of PAI-1 persisted, allowing further discrimination between low- and high-risk patients. In multivariate analysis, residual tumour mass (P < 0.001, relative risk (RR) 4.5), PAI-1 (P < 0.001; RR 3.1) and nodal status (P = 0.022, RR 2.6) turned out to be strong, statistically independent prognostic parameters. Evaluation of the time-dependent prognostic impact of residual tumour mass and PAI-1 on overall survival (n = 86, 50 months) revealed that the prognostic power of these factors increased with time. In patients with advanced ovarian cancer, both residual tumour mass and PAI-1 are statistically independent strong prognostic factors. Even within patient subgroups with or without residual tumour mass, PAI-1 allowed selection of patients at risk who might benefit from individualized therapy protocols.

Urokinase and plasminogen activator-inhibitor (PAI-1) status in primary ovarian carcinomas and ovarian metastases compared to benign ovarian tumors as a function of histopathological parameters

Ninety-eight patients with histologically confirmed ovarian tumors (77 primary ovarian carcinomas of stages T1 to T3 according to the postoperative histopathological classification pTNM classification, 14 ovarian metastases of various origins and seven benign ovarian tumors) were investigated with regard to the concentration of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor (PAI-1) in membrane extracts of tumors. The results were correlated with the clinical course and with histopathological findings. With more advanced stage of primary ovarian carcinomas, there was a highly significant rise in the membrane concentrations of both uPA and PAI-1. However, increasing dedifferentiation of the tumors correlated only with uPA, but not with PAI-1. There was no correlation between the number of steroid receptors for estradiol and progesterone and the content of uPA or PAI-1 in the primary ovarian carcinomas. In the 14 ovarian metastases of different origins incluced in the study, the contents of uPA and PAI-1 were comparable to those of primary ovarian carcinomas. Compared with the malignant ovarian tumors, the median uPA and PAI-1 concentrations in the membrane fraction were 2.5-6 fold lower (highly significant) in the group of seven benign tumors. A cut-off value of 4.8ng/mg pellet protein for a prognostically favorable (< 4.8) or unfavorable course (> 4.8) could be determined for uPA (p = 0.0392) but not for PAI-1 on the basis of the Kaplan and Meier survival curves in the malignant primary ovarian carcinomas.

High tissue content of urokinase plasminogen activator (u-PA) is associated with high stromal expression of u-PA mRNA in poorly differentiated serous ovarian carcinoma

Urokinase plasminogen activator (u-PA) plays a pivotal role in tissue degradation during tumor spread and metastasis. We have quantitated u-PA in tissue homogenates of 31 serous ovarian tumors and localized u-PA and its mRNA in tissue sections of 26 serous ovarian tumors. The content of u-PA was higher in malignant than in benign tumors, with the highest levels being found in poorly differentiated cancers. In tissue sections, the u-PA mRNA was hybridized with a radiolabeled RNA probe. Signals were almost exclusively found in the epithelium in benign and borderline tumors and in well-differentiated cancers. Poorly differentiated tumors and metastases exhibited prominent stromal expression of u-PA mRNA, whereas epithelial expression was weak or absent. Immuno-histochemical staining co-localized u-PA antigen with its mRNA in the epithelium of benign and borderline tumors and in well-differentiated cancers. Poorly differentiated malignant tumors showed extensive immunostaining in the epithelium in addition to stromal staining. The u-PA mRNA-expressing and u-PA-immunostained cells in the stroma were not tumor cells since no cells in the stroma were positive for cytokeratin. Poorly differentiated tumors had increased numbers of stromal macrophages (CD68), and they co-localized with some of the u-PA-positive cells. The presence of u-PA antigen and the absence of u-PA mRNA in tumor epithelium of poorly differentiated tumors and metastases together with the presence of u-PA mRNA in the stroma suggests production in stromal cells and subsequent binding to receptor sites in tumor cells.

Discordant expression of mRNA and protein for urokinase and tissue plasminogen activators (u-PA, t-PA) in endometrial carcinoma

Tissue samples were obtained from normal (n = 92), hyperplastic (n = 22) and malignant (n = 35) endometria. Urokinase and tissue plasminogen activators (u-PA, t-PA) were assayed in acetate detergent buffer extracts and their mRNAs quantitated in autoradiograms of Northern blots. The tissue content of u-PA was significantly higher in adenocarcinomas compared to normal and hyperplastic endometria. Tumors with poor differentiation and extensive myometrial invasion had the highest levels. The content of t-PA was increased in hyperplastic endometria but not in adenocarcinomas. The tissue content of t-PA was inversely related to clinical stage and loss of differentiation in malignant tumors. In contrast to the protein data, u-PA mRNA was not higher and t-PA mRNA was much lower in malignant compared to benign tumors. Thus, high tumor tissue content of u-PA does not result from transcriptional regulation, and reduction of t-PA mRNA may indicate down-regulation of transcription or possibly reduced mRNA stability. Furthermore, the discrepancy between protein and mRNA for both activators probably indicates up-regulation of the translation process since decreased degradation of activator proteins is a less likely explanation.

Dipeptidyl peptidase III in malignant and non-malignant gynaecological tissue

Exopeptidases, in contrast to endopeptidases (proteinases) have been much less studied in relation to cancer. The aim of this study was to investigate one such enzyme, dipeptidyl peptidase III (DPP III), in gynaecological tissues, by measuring both the enzyme activity and enzyme content. DPP III activity was assessed in normal (n = 65), benign (n = 9) and malignant (n = 51) gynaecological tissues. A statistically significant higher DPP III activity was observed in endometrial (n = 40, P = 4.6 x 10(-7)) and ovarian (n = 11, P = 8.1 x 10(-4)) malignant tumours, whereas no significant difference was detected for leiomyomas (n = 8), if compared to the activity in normal tissue. A matched pair analysis of normal and cancerous endometrial tissue confirmed the significance of the DPP III activity increase in the transformed tissue (n = 7, P = 0.022). Western blot analysis revealed a significantly (P = 0.014) increased level of DPP III in endometrial cancer. Further, regression analysis showed a positive correlation between the activity and the content of DPP III in normal tissue (r = 0.637, P = 0.047) and in endometrial cancer (r = 0.574, P < 0.007). The increase of the DPP III activity was observed in the endometrial carcinomas of various histological types, grade or the depth of myometrial invasion. The easy-to-perform determination of this exopeptidase activity may serve as a potential indicator of endometrial and ovarian malignancies.

Alterations in plasminogen activation correlate with epithelial cell dysplasia grading in colorectal adenomas

Proteases are important for neoplastic invasion but a specific role for the plasminogen activator system in the progression of colorectal epithelial dysplasia to adenomatous lesions remains unclear. Consecutive tissue cryosections of 51 adenomas, 49 distant mucosa samples and five mucosa samples from control subjects were histopathologically analysed for dysplasia grade and tissue type, urokinase plasminogen activator levels and plasminogen activator inhibitor type 1 (PAI-1) using immunosorbent methods. Plasminogen activation and urokinase-mediated proteolytic activity levels were assessed using in situ zymography. Plasminogen activation and tissue-type activator levels were lower in adenomas than in mucosae (P < 0.001). PAI-1 concentration and urokinase levels were higher in adenomas than in mucosae (P < 0.001 and P < 0.001 respectively). In adenomas, urokinase concentration increased in parallel with PAI-1, but only the urokinase levels correlated with the dysplasia grade (P < 0.01). Thus, the alterations in plasminogen activation correlated with epithelial cell dysplasia grading. In the mucosa to adenoma transition, a marked decrease in tissue-type plasminogen activator occurred. In adenomas, this decrease was accompanied by a concomitant increase in urokinase and PAI-1. The urokinase level only continued to rise in parallel with the dysplasia grade. Resulting protease-antiprotease imbalance in high-grade dysplasia may represent the phenotypic change associated with malignant transformation and invasive behaviour.

Expression of plasminogen activator inhibitor-2 in epithelial ovarian cancer: a favorable prognostic factor related to the actions of CSF-1

In ovarian cancer cells, the macrophage colony-stimulating factor-1 (CSF-1) induces the release of plasminogen activator inhibitor-2 (PAI-2), and high levels of PAI-2 as well as of CSF-1 in ovarian cancer ascites are independently correlated with poor outcome. We now study the effect of CSF-1 on PAI-2 expression in vitro and the significance of cellular PAI-2 expression in vivo. Immunohistochemical detection of PAI-2 was studied in primary and metastatic tissues from 130 epithelial ovarian cancer cases. Kaplan-Meier curves of survival were compared with the results of log-rank test. The Cox regression model was used for multivariate analysis. The effect of CSF-1 on PAI-2 expression in ovarian cancer cells was also examined in vitro. Fifty-eight percent of the primary tumors and 68% of the metastases expressed PAI-2. PAI-2 expression in the metastases of invasive stages III and IV cases was strongly predictive of a prolonged disease-free and overall survival. This finding was associated with low residual disease and was also an independent factor for disease-free survival. In vitro, CSF-1 treatment of ovarian cancer cells resulted in a decrease in cellular staining for PAI-2 while increasing the release of PAI-2 into the conditioned medium. In vivo, we also found an inverse correlation between expression of CSF-1 and that of PAI-2 in the primary tumors. We thus describe the favorable independent prognosis of cellular PAI-2 expression in the metastases of ovarian cancer. Moreover, an inverse correlation was observed between CSF-1 and PAI-2 expression in vivo. This lends support for a primary role of cell-surface (vs. secreted)-mediated events of plasminogen activation in the development of invasive, poor prognostic phenotypes.

Establishment of long-term in vitro cultures of human ovarian cystadenomas and LMP tumors and examination of their spectrum of expression of matrix-degrading proteinases

OBJECTIVES

To obtain long-term cultures of ovarian cystadenomas and ovarian tumors of low malignant potential (LMP) displaying gene expression patterns similar to those found in vivo and test the hypothesis that such cultures would express different levels of matrix-degrading proteinases than cultured ovarian carcinomas.

METHODS

Transfection with an adenoviral expression vector for simian virus 40 (SV40) large T antigen was used to establish long-term cultures of the above tumors. Levels of expression of various genes were evaluated using molecular biological and immunohistochemical approaches. Zymography and reverse zymography were used to examine the activity of various metalloproteinases and plasminogen activators (PA). Two-sided P values for differences in plasminogen activator expression between different cell types were evaluated by Fisher's exact test.

RESULTS

Long-term cultures derived from cystadenomas and LMP tumors were obtained which formed colonies on semisolid supports, but were not tumorigenic in nude mice. The cultured cells expressed keratin, estrogen receptor, gonadotropin receptors, BRCA1, and originated from monoclonal populations. There was no apparent association between the malignant phenotype and the expression of either matrix metalloproteinases or tissue inhibitors of metalloproteinases. However, a correlation was seen between this phenotype and expression of urokinase (uPA) and tissue type (tPA) plasminogen activators (P = 0.08 and 0.02 respectively).

CONCLUSIONS

The above cell strains provide a useful model for investigating various aspects of the biology of benign ovarian tumors, including their response to steroid and gonadotropin hormones, and the role of specific proteinases in the acquisition of invasive and metastatic abilities.

Biochemical characterization of primary peritoneal carcinoma cell adhesion, migration, and proteinase activity

Primary papillary serous carcinoma of the peritoneum (PPC) is clinically and histologically similar to advanced stage epithelial ovarian carcinoma. PPC classically presents with widespread intraperitoneal dissemination, superficial invasion, and minimal ovarian involvement. Surgical cytoreduction and combination chemotherapy utilized for patients with epithelial ovarian carcinoma have produced varying results for patients with PPC. These differences in response may be secondary to the stage of disease or due to biological differences in metastatic behavior between these carcinomas. In this study, short-term primary cultures of PPC and epithelial ovarian carcinoma (OVCA) were compared to enable biochemical comparison with respect to components of the metastatic cascade including adhesion, migration, and proteinase activity. These data demonstrated similar properties in adhesive profiles of PPC and OVCA, with preferential adhesion to type I collagen and vitronectin. Matrix-degrading proteinases including matrix metalloproteinases (MMP)-2, MMP-9, and urinary-type plasminogen activator were produced by both cell types. PPC migration was stimulated by multiple extracellular matrix proteins, whereas OVCA cells demonstrated maximal migration on type I collagen coated surfaces. Together our data suggest biochemical similarities between PPC and OVCA with respect to individual components of the metastatic cascade.

Production of extracellular matrix-degrading proteinases by primary cultures of human epithelial ovarian carcinoma cells

BACKGROUND

The authors analyzed the secretion of extracellular matrix-degrading proteinases, including urinary-type plasminogen activator (u-PA), matrix metalloproteinase-2 (MMP-2, gelatinase A), and MMP-9 (gelatinase B), by short term primary cultures of epithelial ovarian carcinoma cells derived from primary ovarian tumors, intraperitoneal metastases, or ascites. The presence of these enzymatic activities in samples of ascites was also evaluated. The effect of adhesive substratum on proteinase production was determined.

METHODS

A coupled spectrophotometric assay was utilized to evaluate the initial rate of plasminogen activation by u-PA in conditioned medium; this involved monitoring the activity of generated plasmin with a colorimetric substrate. MMP activity was evaluated by gelatin zymography.

RESULTS

Ascitic fluids from 18 patients contained u-PA, MMP-2, and MMP-9. However, short term primary cultures of cells derived from primary ovarian tumors (OVET), metastatic lesions (OVEM), or ascites (OVEA) produced very low levels of u-PA. Production of u-PA by OVET and OVEM cells was regulated by adhesive substratum. Conditioned media from OVET, OVEM, and OVEA cells contained high levels of both MMP-2 and MMP-9. MMP-9 levels decreased with increasing passage in culture, whereas MMP-2 activity was maintained. Production of neither MMP-2 nor MMP-9 was regulated by adhesive substratum.

CONCLUSIONS

These results demonstrate that primary cultures of epithelial ovarian carcinoma cells derived from three distinct anatomic locations produce MMP-2 and MMP-9, with low level secretion of u-PA. These data suggest that MMPs, particularly MMP-2, may play a significant role in the intraperitoneal invasion of ovarian carcinoma cells.

Altered Tumor Growth and Metastasis of a T-Cell Lymphoma in Timp-1 Transgenic Mice

The concept of tumor suppression by tissue inhibitor of metalloproteinases (TIMPs) has evolved primarily from studies of genetically modulated tumor cells. The next step is to focus on the host and assess the protective potential of host TIMP-1 on primary tumor growth and metastasis. We generated two transgenic mouse lines with altered Timp-1 expression in skin and liver: one overexpressed Timp-1 (Timp-1high), and the other had antisense RNA–mediated Timp-1 reduction (Timp-1low). ESbL-lacZ T-lymphoma cells provided the tumor challenge, as they form primary tumors upon intradermal injection with spontaneous metastasis to liver. Metastases were examined in X-Gal–stained whole-organ mounts. Timp-1 overexpression inhibited intradermal tumor growth and spontaneous metastasis, leading to prolonged survival of the mice. The opposite effects occurred in Timp-1low mice, leading to shorter host survival. Experimental metastasis assays showed that Timp-1–compromised livers in Timp-1low mice showed at least a doubling of metastatic foci and numerous additional micrometastases, indicative of increased host susceptibility. However, Timp-1high mouse livers showed an unaltered metastatic load in the experimental metastasis assay. In conclusion, these data demonstrate that Timp-1 levels within a tissue predetermine the development and progression of T-cell lymphoma.

Defective cell migration in an ovarian cancer cell line is associated with impaired urokinase-induced tyrosine phosphorylation

The urokinase receptor (u-PAR), a protein anchored to cell membrane by a glycosyl phosphatidylinositol, plays a central role in cancer cell invasion and metastasis by binding urokinase plasminogen activator (u-PA), thereby facilitating plasminogen activation. Plasmin can promote cell migration either directly or by activating metalloproteinases that degrade some of the components of the extra cellular matrix. However, the IGR-OV1-Adria cell line contains the u-PAR but does not migrate even in the presence of exogenous u-PA, although the parental IGR-OV1 cell line migrates normally in the presence of u-PA. We therefore investigated the role of cell signalling for u-PA induced cell locomotion. We show that cell migration induced by u-PA-u-PAR complex is always associated with tyrosine kinase activation for the following reasons: (1) the blockade of the u-PAR by a chimeric molecule (albumin-ATF) inhibits not only the u-PA-induced cell migration, but also the signalling in IGR-OV1 line; (2) the binding of u-PA to u-PAR on non-migrating IGR-OV1-Adria cells was not associated with tyrosine kinase activation; (3) the inhibition of tyrosine kinase also blocked cell migration of IGR-OV1. Therefore tyrosine kinase activation seems to be essential for the u-PA-induced cell locomotion possibly by the formation of a complex u-PAR-u-PA with a protein whose transmembrane domain can ensure cell signalling. Thus, IGR-OV1 and IGR-OV1-Adria cell lines represent a good model for the analysis of the mechanism of u-PA-u-PAR-induced cell locomotion.

Expression of urokinase-type plasminogen activator (uPA) and its inhibitor PAI-1 in benign, borderline, malignant primary and metastatic ovarian tumors

Elevated levels of expression of the urokinase-type plasminogen activator (uPA) and its inhibitor PAI-1 have shown to be related to poor prognosis in a variety of cancer types. In the present study, cytosolic levels of uPA and PAI-1 were determined with enzyme-linked immunosorbent assays in cytosols prepared from 244 human ovarian tissues of different histological sub-types. Both uPA and PAI-1 were significantly associated with the malignant progression of ovarian tissues; the levels were increased going from normal tissue, via benign and borderline adenomas, to primary and metastatic adenocarcinomas. For the 90 patients (34 early-stage and 56 patients with advanced disease) from whom the primary adenocarcinoma tissues were examined, uPA and PAI-1 levels were evaluated for their association with clinicopathological parameters and with progression-free and overall survival. Neither uPA nor PAI-1 were significantly associated with the age of the patient, FIGO stage, tumor grade, tumor rest, the presence of ascites, or with progression-free or overall survival. On the other hand, age, FIGO stage/tumor rest and the presence of ascites, were significantly related to the length of both progression-free and overall survival in univariate analyses. Tumor grade was of prognostic significance in the analysis for progression-free survival, but not for overall survival. After adjustment for FIGO stage/tumor rest, only age retained its prognostic significance, in the analysis for progression-free survival and in that for overall survival.

Evidence for preferential adhesion of ovarian epithelial carcinoma cells to type I collagen mediated by the alpha2beta1 integrin

Epithelial ovarian carcinoma, the leading cause of gynecologic cancer death, is characterized by widespread intra-abdominal metastases mediated primarily by surface shedding of tumor cells and peritoneal implantation. Whereas hematogenous metastasis is known to involve cellular adhesion, extracellular matrix proteolysis and cell migration, the role of these processes in the intraperitoneal dissemination of ovarian cancer remains unclear. To analyze further the role of adhesion and proteolysis in ovarian carcinoma dissemination, we have characterized the adhesive profiles of 4 primary cultures of ovarian carcinoma cells and 5 ovarian carcinoma cell lines. Our data demonstrate preferential adhesion of ovarian carcinoma cells to interstitial type I collagen. Analysis of adhesion molecule expression demonstrated the presence of the alpha2 and beta1 integrin subunits by cell surface ELISA, immunoprecipitation and immunohistochemistry. Furthermore, antibodies directed against the alpha2 and beta1 subunits inhibited adhesion of ovarian carcinoma cells to type I collagen by 56% and 95%, respectively. Plasminogen activator and matrix metalloproteinase production by adherent cells was not altered as a consequence of adhesion to individual extracellular matrix proteins; however, adhesion to an extracellular matrix comprised primarily of interstitial collagen increased plasminogen activator activity in 5 of 5 cell lines. Since the ovarian carcinoma micro-environment is rich in type I collagen, our data suggest that preferential adhesion to type I collagen followed by secretion of serine and metalloproteinases may represent a biochemical mechanism by which the intraperitoneal dissemination of ovarian carcinoma is mediated.

Plasminogen activators in oesophageal carcinoma

The expression of components of the plasminogen activator system was investigated in patients with oesophageal carcinoma. Tumour and normal mucosa were obtained from resected oesophageal carcinomas and antigens were measured by enzyme-linked immunosorbent assay. Median levels of urokinase plasminogen activator (uPA) and the uPA receptor were higher in carcinoma than in matched normal mucosa (squamous cell carcinoma: uPA 4.05 versus 0.66 ng antigen per mg protein, uPA receptor 1.95 versus 0.50 ng/mg, n = 10, P < 0.05; adenocarcinoma: uPA 2.16 versus 0.61 ng/mg, uPA receptor 2.01 versus 0.49 ng/mg, n = 8, P < 0.05). Tissue plasminogen activator (tPA) level was lower than control values in squamous cell carcinoma but not in adenocarcinoma (1.97 versus 4.70 ng/mg, P < 0.05). There was no difference in plasminogen activator inhibitor (PAI) 1 level between carcinoma and normal mucosa. The PAI-2 level was lower than that in normals in adenocarcinoma only (6.0 versus 64.77 ng/mg, P < 0.05). These data support the hypothesis that membrane-bound uPA has a role in the breakdown of extracellular matrix in invasive oesophageal carcinoma.

Urokinase-type plasminogen activator expression in human prostate carcinomas

The prostate gland is the most common site of cancer in men in the United States. The biologic behavior of an individual tumor, however, varies widely, with some cancers taking a relatively indolent course and other progressing rapidly to disseminated disease. Prognostic factors that might help predict a tumor's aggressiveness and invasiveness are limited. The expression of urokinase plasminogen activator was evaluated in 36 human prostate cancer specimens. Using an immunohistochemical method with monoclonal antibody #394, 70.6% (12 of 17) of cancer specimens with extracapsular extension showed increased expression of urokinase plasminogen activator, compared with 26.6% (4 of 15) of specimens without capsular invasion. Increased expression was localized to the glandular cytoplasm, with tumor stroma yielding predominantly negative results. These findings provide additional evidence of the role of urokinase in determining the biologic behavior and metastatic potential of prostate cancer.

The plasminogen activation system in tumour invasion and metastasis

The involvement of proteases in the metastatic spread of tumour cells and in tumour related processes, such as angiogenesis and ulceration, has been known for many decades. This chapter reviews the involvement of one proteolytic system--the plasminogen activation system--in tumour progression. In recent years, many biochemical properties of the various components of the plasminogen activation system have become known. These properties and the functional relationship between the components are discussed in the first section. Since interfering with proteolysis by tumour cells and by newly formed endothelial cells can be an objective for future therapy, experimental tumour models have been used to study the effects of inhibitors of plasminogen activation. The second section deals with this issue. Finally, the presence of the various components of the plasminogen activation system in human tumours is reviewed. Following the availability of specific ELISAs, antibodies and molecular probes, the content and the cellular distribution of the components of the plasminogen activation system have recently been mapped in various human tumours.

Blood and tissue fibrinolytic profiles in patients with colorectal carcinoma

In patients with colorectal cancer, profound alterations of the plasminogen activator system have been described at the tumor level, but conflicting results have been obtained for fibrinolytic parameters in plasma. Components of the fibrinolytic system, including tissue-type and urokinase-type plasminogen activators and their inhibitors type 1 and 2, were measured in tissue and/or plasma from 41 patients with colorectal cancer and in 40 controls. Procoagulant activity of freshly isolated mononuclear cells (basal activity) and the procoagulant activity and fibrinolytic proteins produced by the cells after incubation for 18 h without exogenous stimulation were also evaluated. Malignant tissue extracts had significantly higher levels of urokinase-type plasminogen activator and plasminogen activator inhibitor-1, but lower levels of tissue-type plasminogen activator than normal mucosa. Plasminogen activator inhibitor-1 alone was higher in advanced (Dukes' stages C + D) than limited (B) tumors. Plasminogen activator inhibitor-2 was not different in malignant tissue and normal mucosa. Plasma levels of plasminogen activator inhibitor-1 antigen were significantly increased in cancer patients compared with controls, but there were no differences in tissue-type and urokinase-type plasminogen activator, in plasminogen activator inhibitor-2, and D-dimer levels. Intra-patient analysis revealed no significant correlation between tumor and plasma levels of plasminogen activators or type 1 inhibitor. Tissue-type plasminogen activator, but not the urokinase type or inhibitor type 1, was higher in venous than in arterial blood collected at the tumor site during surgery. Basal procoagulant activity of mononuclear cells and the procoagulant activity and inhibitor type-2 produced by the cells after short-term culture were comparable in patients and controls. These findings indicate that, at least in our patients with colorectal cancer, the profound changes occurring at tumor level are barely detectable in the blood. Thus, the clinical relevance of plasma fibrinolytic parameters, especially urokinase-type plasminogen activator antigen, as tumor markers in colorectal cancer remains to be established.

Increase of a urokinase receptor-related low-molecular-weight molecule in colorectal adenocarcinomas

Proteolytic activity is important for tumor growth and metastasis. Plasminogen and urokinase-type plasminogen activator (u-PA) constitute one of the most extensively studied proteolytic systems believed to participate in these processes. u-PA cleaves plasminogen to plasmin, which in turn degrades surrounding extracellular matrix and allows tumor cells to migrate to other areas. The specific receptor for u-PA (u-PAR) has also been implicated as an essential modulator in this pathway. Eleven paired samples of colorectal cancers and normal mucosal tissues from the same patients were removed at surgery. The tissues were homogenized and the supernatants assayed for u-PAR immunoreactivity, u-PAR antigen concentration, u-PAR binding activity and u-PA activity. Immunoblot analysis showed that a major u-PAR species of approximately 55 kDa was present in all tissues. In addition, a protein band of approximately 41 kDa, which crossreacted with anti-u-PAR antibodies, was also found in the tumors. This protein band was either absent, or present in relatively small amounts in the normal colorectal tissues. Cross-linking experiments showed that the approximately 55 kDa band only, and not the approximately 41 kDa band, was able to bind either single chain urokinase-type plasminogen activator (scu-PA) or the amino terminal fragment of urokinase (ATF). The tumor samples also exhibited highly elevated u-PA activity and u-PAR antigen relative to the corresponding normal tissues. Elevated u-PA activity appeared to correlate with elevated u-PAR antigen in colorectal cancers, but not in the normal tissues. These increases were also associated with increase of the u-PAR-related, low-molecular-weight protein in the tumor samples. The measurement of u-PAR and the u-PAR-related protein, in addition to u-PA activity, could have diagnostic or prognostic value in this type of cancer.

The urokinase/urokinase-receptor system and cancer invasion

u-PA binds with high affinity to its specific GPI-anchored receptor on the cell surface. The binding has at least two important consequences: (1) it enhances the rate of plasminogen activation on the cell surface; and (2) it focuses the u-PA proteolytic activity at the leading front of migrating cells. Several recent findings suggest that surface-bound u-PA is essential for the invasive ability of tumour cells, even if a picture is emerging indicating a concerted action with other proteases, like collagenases and cathepsin B (Kobayashi et al, 1992; Ossowski, 1992; Schmitt et al, 1992; (Danø et al, 1994). In some tumours, e.g. colon, breast and skin cancer, in situ hybridization studies have given an insight into the u-PA/u-PAR tumour biology showing a complex interplay between stromal and cancer cells Danø et al, 1994). u-PA, u-PAR, and PAI-1 tumour content are now well established prognostic factor in breast cancer. This body of knowledge could be used for theurapeutic purposes. For example, a large study with 671 patients has allowed the identification of node-negative patients which, according to their u-PA levels, would need adjuvant therapy (Foekens et al, 1992). Many other tumours, especially colorectal cancer, expect a direct clinical evaluation of u-PA, u-PAR and serpins as prognostic factors.

Components of the plasminogen activation system in uveal melanoma--a clinico-pathological study

In tumour development, proteases such as plasminogen activators (PAs) play a role in degradation of the extracellular matrix and other tissue barriers. Recently, we demonstrated that plasminogen activators, their inhibitors, and urokinase receptor emerge in late stages of cutaneous melanocytic tumour progression. In this study we investigated the expression and distribution of the various components of the PA system and the presence of PA enzyme activity in 45 freshly frozen primary uveal melanoma with known follow-up (14 spindle and 31 non-spindle type) and in metastases (n = 5). Tissue-type PA (t-PA) was found in endothelium of blood vessels and in tumour cells in almost all lesions, and was markedly present at the invasive front (towards the sclera and Bruch's membrane), but no correlation with tumour-related death could be established. Urokinase PA (u-PA) was expressed focally, by only five non-spindle cell melanomas but in all metastases. u-PA expression correlated with occurrence of metastasis. u-PA receptor (u-PAR) was present in one-third of all the tumours examined. Plasminogen activator inhibitors (PAI-1 and PAI-2) were found only focally in approximately 10 per cent of the lesions. Staining of t-PA, u-PA, and PAI was observed in all the metastases. We conclude that in uveal melanoma, u-PA expression may be associated with metastatic disease and accordingly with a poor prognosis. Further research on a larger group of tumours with known follow-up is needed to establish whether u-PA positivity is of additional prognostic value in uveal melanoma.

Activities, localizations, and roles of serine proteases and their inhibitors in human brain tumor progression

The plasminogen activation system consists of plasminogen activators and their inhibitors, serine proteases, and serpins. The proteases and inhibitors regulate a variety of processes in tissue morphogenesis, differentiation, cell migration, and cancer cell invasiveness and metastasis. One of the plasminogen activators, urokinase-type plasminogen activator (uPA), binds to a specific surface and provides a localized cell surface proteolytic activity required for the destruction of extracellular matrix, which is a vital step in tumor cell invasion. The proteolytic activity of uPA is modulated by its cell surface receptor, as well as by plasminogen activator inhibitor type-1 (PAI-1) and, to a lesser degree, by other inhibitors. The role of plasminogen activators and their inhibitors in cancer invasion can be demonstrated in the development and progression of malignant brain tumors. Our findings indicate that uPA and PAI-1 expression are dramatically upregulated in malignant brain tumors in parallel with the histological progression of the tumors. The results suggest that these molecules may contribute to tumor invasion in addition to their significant role in angiogenesis. An evaluation of the plasminogen activation system could add diagnostic and prognostic significance to the evaluation of individual patients.