A comparison of the growth promoting properties of ascitic fluids, cyst fluids and peritoneal fluids from patients with ovarian tumours

Immunosuppressive Factors: Role in Cancer Development and Progression

The concept of the immunological surveillance against neoplastic cells was initially proposed by Erlich in 1909 and later elaborated by Burnet. This hypothesis states that the normal function of the immune system, in particular the cell-mediated immunity, is to recognize and destroy the transformed and proliferating tumor cells. The role of cell-mediated immunity during the first steps of tumorigenesis remains controversial. However, there is certain evidence about its importance in the progression and dissemination of cancer. The frequent immunosuppressed condition of cancer patients at tumor relapse or recurrence of secondary tumors is a clinical sign supporting this hypothesis, and many studies have demonstrated a defective immune response in patients diagnosed with advanced cancer. Several mechanisms of escape from the immune surveillance have been described, including the immunoselection of tumor antigen-negative variants, the downregulation of MHC class I expression, suppressive T cells, and the elaboration of immunosuppressive cytokines and other factors. Because of the technical difficulty of isolating the very small amounts from culture supernatants or body fluids, only a few of these substances have been characterized and studied with respect to their biological activity: transforming growth factor-β (TGF-β), the protein p15E, interleukin 10 (IL-10), prostaglandin E2 (PGE2), mucins, suppressive E-receptor (SER), immunosuppressive acidic protein (IAP), and adhesion molecules. The possibility of monitoring cancer patients by testing biochemical factors related to cancer growth led to a proposal to measure a number of these factors as tumor markers. Some of them, e.g mucins, enjoy the consensus of the oncologic community, as for some indications they can help the clinician in the management of cancer patients. Except for the class of mucins, the other above-mentioned immunosuppressive factors have not found any clinical application in the laboratory routine because the information deriving from their measurement, although of speculative and scientific interest, has limited clinical value at present. Nevertheless, even if they have no impact on patient management, these substances do have a potential role to play in the study of cancer patients, and should be taken into account when developing new therapeutic strategies.

Human ovarian cancer ascites fluid contains a mixture of incompletely degraded soluble products of fibrin that collectively possess an antiangiogenic property

Ovarian cancer ascites fluid (OCAF) displayed an antiangiogenic property in a chick chorioallantoic membrane (CAM) assay. This property was attributed in part to angiostatin although angiostatin-free OCAF retained a net antiangiogenic property. Recently, immunopurified fibrin(ogen) degradation products (FDPs) from malignant effusions of VX2 tumor-burdened rabbits exhibited antiangiogenic activity on the CAM. We questioned whether the FDPs of OCAF were also antiangiogenic. FDPs were immunopurified from individual OCAF samples, characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis /western blots, enzyme-linked immunosorbent assays, and CAM assays. FDPs of OCAFs consisted of soluble high molecular weight (MW) fragments (>200 kd; approximately 40% of total FDPs), D-dimer (approximately 180 kd; approximately 37%), fragment D (approximately 90 kd; approximately 15%), and fragment E (approximately 50 kd; approximately 8%); intact fibrinogen was absent. When applied to CAM surfaces (0.5-1.6 mg/10 mL), purified FDPs significantly reduced the area of chorionic capillaries from 90% (in controls) to 47% over a 48-h period; from CAM sections, capillary density was reduced from 60% (controls) to 26%. FDPs prepared from fibrinogen displayed a similar antiangiogenic effect. Further digestion of OCAF FDPs by human plasmin caused degradation of high MW fragments, releasing additional D-dimer, fragment D, and fragment E. Of the fibrinogen-related components, OCAF contained only soluble FDPs (including incompletely digested fibrin fragments). Collectively, these FDPs contributed to the net antiangiogenic property of ascites fluid.

Comparison of hepatocyte growth factor levels of epithelial ovarian cancer cyst fluids with benign ovarian cysts

Hepatocyte growth factor (HGF) is known to take role in oncogenesis and tumoral behavior of the tumors of the organs that contain mesenchymal and epithelial cells together. This study aims to compare HGF levels in cyst fluids of epithelial ovarian cancer and benign ovarian cysts and look for the role of HGF in ovarian carcinogenesis. Twenty-four consecutive patients with ovarian cancer and 34 with benign cysts of ovary were recruited prospectively at Gynecologic Oncology Departments of SSK Ankara Maternity Hospital and Hacettepe University School of Medicine between 2001 and 2002. Cyst fluids were collected during primary staging in cancer patients and during laparatomy for benign patients. HGF levels were measured by enzyme-linked immunosorbent assay method. Median HGF levels of the benign ovarian cysts and epithelial ovarian tumoral fluids were found as 3822 pg/ml (85-15,253 pgr/ml) and 12,962 pgr/ml (4136-16,025 pgr/ml), respectively. Malign cyst fluids have higher HGF levels when compared with benign ovarian cysts (P < 0.01). This finding suggests that HGF may take a paracrine role in oncogenic differentiation and tumoral development of epithelial ovarian cancers. Mechanisms that take role in HGF secretion and the answers of the neighboring epithelial cells to HGF during tumoral development need to be investigated.

Comparison of HGF (hepatocyte growth factor) levels of epithelial ovarian cancer cyst fluids with benign ovarian cysts

Hepatocyte growth factor (HGF) is known to take a role in oncogenesis and tumoral behavior of the tumors of the organs that contain both mesenchymal and epithelial cells. This study compares HGF levels in cyst fluids of epithelial ovarian cancer and benign ovarian cysts to look for the role of HGF in ovarian carcinogenesis. Twenty-four consecutive patients with ovarian cancer and 34 with benign ovarian cysts were recruited prospectively at the Gynecologic Oncology Departments of SSK Ankara Maternity Hospital and Hacettepe University School of Medicine between 2001 and 2002. Cyst fluids were collected during primary staging in cancer patients and during laparatomy for benign patients. HGF levels were measured by ELISA method. Median HGF levels of the benign ovarian cysts and epithelial ovarian tumoral fluids were found to be 3822 pg/ml (85-15253 pg/ml) and 12962 pg/ml (4136-16025 pg/ml), respectively. Malignant cyst fluids have higher HGF levels when compared with benign ovarian cysts (P < 0.01). This finding suggests that HGF may take a paracrine role in oncogenic differentiation and tumoral development of epithelial ovarian cancers. Mechanisms that take a role in HGF secretion and the responses of neighboring epithelial cells to HGF during tumoral development need to be investigated.

Integrin-linked kinase expression increases with ovarian tumour grade and is sustained by peritoneal tumour fluid

Integrin-linked kinase (ILK) is a serine threonine kinase, overexpression of which promotes tumour growth and invasion through deregulation of the cell cycle. This study demonstrates the relative expression of ILK in normal, benign, low-grade, and high-grade (borderline, grade I/II, and grade III) ovarian tumours of serous, mucinous, endometrioid, and clear cell types in order to assess its potential as a marker for epithelial ovarian cancer progression. Seventy-three specimens including ten normal, ten benign, 14 borderline, 17 grade I/II, and 22 grade III were evaluated by immunohistochemistry. Immunoreactive ILK was not detectable in normal ovarian surface epithelium. All 53 carcinomas studied were positive and the staining intensity correlated significantly with the grade of the tumour. Ovarian cancer cell lines had high expression of ILK, while immortalized normal ovarian surface epithelial cell lines (HOSE) showed low basal expression of ILK by western blotting. Peritoneal tumour fluid (PTF) upregulated ILK expression in ovarian cancer cell lines but had no effect on HOSE cells. PTF-induced up-regulation of ILK expression in ovarian cancer cell lines correlated with the activation of the downstream protein kinase B (PKB/Akt) pathway. Collectively, these data demonstrate that ILK expression increases with ovarian cancer progression and that soluble factors in PTF mediate sustained overexpression of ILK in ovarian cancer cells. Suppression of ILK expression may therefore represent a novel and an efficient mechanism for controlling ovarian tumour growth.

Malignant ascites fluid (MAF), including ovarian-cancer-associated MAF, contains angiostatin and other factor(s) which inhibit angiogenesis

OBJECTIVE

The aim was to determine whether human malignant ascites fluid (MAF) associated with abdominal cancer, including ovarian cancer, contained factors which inhibit angiogenesis as well as others which stimulate this process.

METHODS

MAF was collected from six patients, four with ovarian cancer, one with gastric cancer, and one with liver metastases. Using the chick chorioallantoic membrane (CAM) the effect of MAF on 7-day-old CAM capillaries was examined for 48 h. Vascular endothelial growth factor (VEGF) was evaluated by ELISA. Five samples of MAF were fractionated by lysine-Sepharose chromatography and the lysine-bound and -unbound fractions were eluted by epsilon-amino-n-hexanoic acid. Whole MAF, the lysine-bound and -unbound fractions, and human angiostatin were subjected to SDS-PAGE/Western blot analysis and immunostained after exposure to anti-human plasminogen. Human plasminogen was exposed to conditioned medium from ovarian epithelial cancer (HEY) cells and subjected to similar Western blot analysis.

RESULTS

Despite containing VEGF, each MAF sample examined caused a loss of capillaries from the CAM; a similar response was seen using purified human angiostatin. Whole MAF and the lysine-bound fraction contained plasminogen (90 kDa) and a 55-kDa protein which migrated in a similar manner to human angiostatin on Western blot. Both the lysine-bound and -unbound fractions caused a loss of capillaries in the CAM. Human plasminogen exposed to conditioned medium from HEY cells yielded a fragment which was similar in size to angiostatin.

CONCLUSIONS

MAF from patients with various clinical presentations contains angiostatin and VEGF as well as other factors which are capable of inhibiting angiogenesis.

Lack of significant differences in the corrected activity of lysophospholipase D, producer of phospholipid mediator lysophosphatidic acid, in incubated serum from women with and without ovarian tumors

BACKGROUND

Several studies have shown that lysophosphatidic acid (LPA), a phospholipidic chemical mediator, is relevant to the pathogenesis of ovarian carcinoma. Higher plasma levels of LPA have been reported in patients with ovarian carcinoma than in healthy patients, and LPA is known to activate ovarian carcinoma cells. To determine the reason for the increased plasma LPA levels in ovarian carcinoma patients, we compared the activities of serum lysophospholipase D, a novel LPA-producing metallo-enzyme, in healthy volunteers, patients with benign ovarian tumor, and patients with ovarian carcinoma.

METHODS

Lysophospholipase D activity was assessed by measuring the percentage conversion of [14C]palmitoyl-lysophosphatidylcholine (LPC) added to human serum. The apparent enzyme activities were corrected based on the serum levels of palmitoyl-LPC determined by gas-liquid chromatography after its purification and conversion to fatty acid methyl esters.

RESULTS

The apparent activity of lysophospholipase D in serum preparations from four patients with ovarian carcinoma at Stage IV was significantly higher than those from five healthy subjects, five patients with benign ovarian tumors, and fourteen patients with ovarian carcinoma at Stages I (n = 5), II (n = 4), and III (n = 5). The serum levels of LPC, an endogenous substrate of lysophospholipase D, in ovarian carcinoma patients were less than those in patients with benign ovarian tumors. There were no significant differences in the corrected lysophospholipase D activity for the LPC levels in healthy women, patients with benign ovarian tumors, and patients with ovarian carcinoma at various stages.

CONCLUSIONS

The current results suggest that lysophospholipase D is not associated with the elevated plasma levels of LPA in ovarian carcinoma patients previously reported, although only a limited number of patients were analyzed.

Hepatocyte growth factor (HGF) in ovarian epithelial tumour fluids stimulates the migration of ovarian carcinoma cells

Hepatocyte growth factor (HGF) is a pleiotropic growth factor implicated in the growth and spread of some epithelial tumours. The epithelial cells of a proportion of ovarian tumours, and some ovarian carcinoma cell lines, express high levels of the HGF receptor, c-Met. In this study, we show that ovarian ascitic fluid as well as benign and malignant ovarian cyst fluids contain significant levels of HGF. Ovarian cyst and ascitic fluid stimulated the migration of the ovarian carcinoma cell line, SK-OV-3, and this was greatly reduced by the addition of an HGF-neutralising antibody. Non-malignant peritoneal fluid contained low levels of HGF, and did not stimulate migration of the SK-OV-3 cells. Our results show that HGF is present in benign and malignant ovarian cyst and ascitic fluid, and that HGF in ovarian tumour fluid may be a major inducer of ovarian carcinoma cell migration.

Transforming growth factor-beta synthesis by human peritoneal mesothelial cells. Induction by interleukin-1

Peritoneal mesothelial cells are uniquely located to regulate cellular events in the peritoneal cavity and are a potentially important source for various cytokines. The present study was designed to elucidate the capacity of human peritoneal mesothelial cells (HPMCs) to synthesize and secrete the transforming growth factor (TGF)-beta isoforms 1, 2, and 3 and to characterize their regulation by inflammatory cytokines. HPMCs constitutively released appreciable amounts of TGF-beta 1 and low amounts of TGF-beta 2 as detected by specific immunoassays. TGF-beta 1 levels secreted within 48 hours (45 +/- 8.9 pg/10(5) cells) were 60-fold higher than TGF-beta 2 levels (0.9 +/- 0.1 pg/10(5) cells), respectively. Treatment of HPMCs with interleukin (IL)-1 beta (10 ng/ml) resulted in a significant increase of both TGF-beta 1 (mean, 5-fold; P < 0.001) and TGF-beta 2 (mean, 6-fold; P < 0.01) generation. After 48 hours of IL-1 beta treatment the levels were 185 +/- 17.1 pg/10(5) cells for TGF-beta 1 and 5.3 +/- 1.5 pg/10(5) cells for TGF-beta 2, respectively. Neither tumor necrosis factor (TNF)-alpha nor interferon (IFN)-gamma (both 10 ng/ml) affected TGF-beta 1 or TGF-beta 2 synthesis by HPMCs. TGF-beta 3 could not be detected in any of the supernatant media. Stimulation of HPMCs with IL-1 beta increased steady-state levels of TGF-beta 1- and TGF-beta 2-specific mRNA. Western blot analysis of supernatants revealed the presence of an immunoreactive band at 25 kd. Indirect competition assays confirmed receptor-binding activity of HPMC-derived TGF-beta. Appreciable amounts of TGF-beta were present in a bioactive form. Our results demonstrate that HPMCs synthesize the TGF-beta isoforms 1 and 2 and that the levels of mRNA and protein release can be up-regulated by the proinflammatory cytokine IL-1 beta.

Colony-stimulating factor-1 in primary ascites of ovarian cancer is a significant predictor of survival

OBJECTIVE

Our purpose was to determine whether the concentration of colony-stimulating factor in ascites of ovarian carcinoma is a prognostic factor for survival.

STUDY DESIGN

Forty-four ascites samples from patients undergoing primary surgery for ovarian carcinoma were measured for colony-stimulating factor-1 by radioimmunoassay. Retrospective analysis of clinical data allowed comparison of accepted prognostic factors to ascites colony-stimulating factor-1 concentration for impact on survival by means of life-table analysis (Kaplan-Meier) by the Wilcoxon test and the Cox regression methods.

RESULTS

In patients with advanced disease (International Federation of Gynecology and Obstetrics stages III and IV, n = 37) ascites colony-stimulating factor-1 concentration levels below a critical cutoff of 8.59 ng/ml were associated with longer overall survival (p < 0.05) and were a better predictor of survival than any other prognostic factor except zero residual disease after cytoreduction. International Federation of Gynecology and Obstetrics stage, tumor histologic type, malignant cells in fluid, grade of tumor, age, and performance status at presentation were not predictive of outcome.

CONCLUSION

Colony-stimulating factor-1 in ascites may be an independent indicator of prognosis in patients with epithelial ovarian cancer.

Ovarian cancer, Part I: Biology

The ovary is among the more complex organs of the body and its functions are achieved by numerous cell types. All of these cell types have some tendency to undergo malignant transformation, but the vast majority of ovarian cancers are believed to be the result of malignant transformation of the ovarian surface epithelium. The concept that most ovarian cancer arises from this modified peritoneal mesothelium is credited to Sir Spencer Wells in 1872. Ovarian cancer is the most frequently fatal gynecologic malignancy, and approximately 20,000 cases per year are diagnosed in the United States. Progress in understanding the biology of this disease, including factors involved in its etiology, progression, and tendency to change from a relatively chemotherapy-sensitive tumor to one with marked drug resistance, has been slow. In this review, the complex features of the normal ovarian surface epithelial cells are considered in relation to the etiology and progression of the disease. The hypothesis that incessant or repetitious ovulation contributes to the initiation of the disease is explored in detail based on experimental data, epidemiologic information, and the potential for antioncogene inactivation in this interesting cell type. Lastly, based on the experimental data available, potential mechanisms of resistance to platinum, the cornerstone of aggressive ovarian cancer therapy, are discussed, as are approaches to overcoming drug resistance. It is hoped that the reader will be left with the feeling that the pace of our understanding of the biology of ovarian cancer is increasing at such a rate that answers to the questions of etiology and why chemotherapy often fails will be known in the foreseeable future.