Gonadotropin stimulation of MLS human epithelial ovarian carcinoma cells augments cell adhesion mediated by CD44 and by alpha(v)-integrin

Progranulin expression induced by follicle-stimulating hormone in ovarian cancer cell lines depends on the histological subtype

Epithelial ovarian cancer (EOC) is a heterogeneous disease that can be categorized into four major histological subtypes. Its etiology remains poorly understood due mainly to this heterogeneity. Follicle-stimulating hormone (FSH) has been implicated as a risk factor in EOC and has been suggested that may influence the development of specific subtypes. In addition, FSH regulates different aspects of ovarian cancer tumorigenesis. FSH downstream target genes in EOC have not been fully identified. Progranulin (PGRN) overexpression is associated with cell proliferation, invasion, chemoresistance, and shortened overall survival in ovarian cancer. Recently, we demonstrated that PGRN expression is regulated through the PI3K signaling pathway in clear cell ovarian carcinoma (CCOC) cells. In contrast, we also demonstrated that PGRN synthesis in serous ovarian cancer (SOC) cells is regulated via PKC but not by the PI3K signaling pathway. Several studies have demonstrated that FSH induces PKC and PI3K activation. Thus, this study was to investigate the effect of FSH on PGRN production in the CCOC cell line TOV-21G as compared to the SOC cell lines SKOV3 and OVCAR3. Cultured TOV-21G, SKOV3, and OVCAR3 cells were incubated with different concentrations of FSH for 48 h. PGRN mRNA and protein expression were assessed by RT-PCR and Western blotting, while PGRN secretion was measured by ELISA. PGRN mRNA and protein expression, as well as PGRN secretion, significantly increased after FSH stimulation in TOV-21G but not in SKOV3 and OVCAR3 cells. These data indicate that FSH induces PGRN expression and secretion only in CCOC cells. Establishing specific features for CCOC could reveal potential diagnostic and therapeutic targets.

Expression of the luteinizing hormone receptor (LHR) in ovarian cancer

We investigated the association of LHR expression in epithelial ovarian cancer (OC) with clinical and pathologic characteristics of patients. LHR expression was examined immunohistochemically using tissue microarrays (TMAs) of specimens from 232 OC patients. Each sample was scored quantitatively evaluating LHR staining intensity (LHR-I) and percentage of LHR (LHR-P) staining cells in tumor cells examined. LHR-I was assessed as no staining (negative), weak (+ 1), moderate (+ 2), and strong positive (+ 3). LHR-P was measured as 1 to 5, 6 to 50% and >  50% of the tumor cells examined. Positive LHR staining was found in 202 (87%) patients' tumor specimens and 66% patients had strong intensity LHR expression. In 197 (85%) of patients, LHR-P was measured in > 50% of tumor cells. LHR-I was significantly associated with pathologic stage (p = 0.007). We found that 72% of stage III or IV patients expressed strong LHR-I in tumor cells. There were 87% of Silberberg's grade 2 or 3 patients compared to 70% of grade 1 patients with LHR expression observed in > 50% of tumor cells, p = 0.037. Tumor stage was significantly associated with overall survival and recurrence free survival, p < 0.001 for both analyses, even after adjustment for age, tumor grade and whether patient had persistent disease after therapy or not. Our study demonstrates that LHR is highly expressed in the majority of OC patients. Both LHR-I and LHR-P are significantly associated with either the pathologic stage or tumor grade.

The role of reproductive hormones in epithelial ovarian carcinogenesis

Epithelial ovarian cancer comprises ∼85% of all ovarian cancer cases. Despite acceptance regarding the influence of reproductive hormones on ovarian cancer risk and considerable advances in the understanding of epithelial ovarian carcinogenesis on a molecular level, complete understanding of the biologic processes underlying malignant transformation of ovarian surface epithelium is lacking. Various hypotheses have been proposed over the past several decades to explain the etiology of the disease. The role of reproductive hormones in epithelial ovarian carcinogenesis remains a key topic of research. Primary questions in the field of ovarian cancer biology center on its developmental cell of origin, the positive and negative effects of each class of hormones on ovarian cancer initiation and progression, and the role of the immune system in the ovarian cancer microenvironment. The development of the female reproductive tract is dictated by the hormonal milieu during embryogenesis. Intensive research efforts have revealed that ovarian cancer is a heterogenous disease that may develop from multiple extra-ovarian tissues, including both Müllerian (fallopian tubes, endometrium) and non-Müllerian structures (gastrointestinal tissue), contributing to its heterogeneity and distinct histologic subtypes. The mechanism underlying ovarian localization, however, remains unclear. Here, we discuss the role of reproductive hormones in influencing the immune system and tipping the balance against or in favor of developing ovarian cancer. We comment on animal models that are critical for experimentally validating existing hypotheses in key areas of endocrine research and useful for preclinical drug development. Finally, we address emerging therapeutic trends directed against ovarian cancer.

OCT4 mediates FSH-induced epithelial-mesenchymal transition and invasion through the ERK1/2 signaling pathway in epithelial ovarian cancer

Our previous study showed that Octamer-binding transcription factor 4 (OCT4) expression was upregulated and significantly associated with histological grade through the analysis of OCT4 expression in 159 ovarian cancer tissue samples, and OCT4 mediated follicle-stimulating hormone (FSH)-induced anti-apoptosis in epithelial ovarian cancer. Nevertheless, whether OCT4 participates in FSH-induced invasion in ovarian cancer is still unknown. Therefore, the present study aimed to define whether FSH-induced ovarian cancer invasion is mediated by OCT4. In present study, we showed that FSH induced not only the epithelial-mesenchymal transition (EMT) and invasive phenotype but also the upregulation of OCT4 expression in a dose- and time-dependent manner in epithelial ovarian cancer cells. In addition, the expression of FSH receptor (FSHR) was upregulated by FSH induction, and knockdown of FSHR inhibited FSH-stimulated OCT4 expression. ERK1/2 signaling pathway participated in the enhanced expression of OCT4 and Snail induced by FSH. We further showed that the activated expression of Snail and N-cadherin, the suppressed expression of E-cadherin and the morphological change of the cells stimulated by FSH were blocked by OCT4-specific small interfering RNA. Moreover, our results showed that OCT4 mediated the increase in invasive capacity induced by FSH in ovarian cancer cells. Taken together, our work reveals that OCT4 is an essential mediator in FSH-induced EMT and invasion in epithelial ovarian cancer and may act as a potential therapeutic target.

Ovarian epithelial tumors and reproductive factors: a systematic review

PURPOSE

The aim of this systematic review is to summarize the current knowledge about the etiology and pathogenesis of borderline tumors ovarian cancer with special emphasis on the role of endocrine treatments and reproductive factors to establish a foundation for future studies.

METHODS

We performed a systematic review on the relation between ovarian epithelial tumors (OET) and reproductive factors using the keywords: ovarian cancer, ovarian tumor, ovarian borderline tumor, age at menarche, age at menopause, parity, infertility, PCO syndrome, oral contraception, menopausal hormone therapy, fertility treatment. Totally, 3,290 abstracts were scanned for their relevance in this publication and 127 were finally included.

RESULTS

The incidence of ovarian epithelial cancer and ovarian borderline tumors is influenced by certain reproductive factors. The strongest protective effects are conferred by parity and use of oral contraceptive pills. Recent molecular biologic and histopathologic studies prove that OET represent a diverse group of tumors, each histologic type with a different genetic background. This is at least partly reflected in epidemiologic and clinical studies showing different risk modulating effects of reproductive factors and endocrine therapies on OET.

CONCLUSIONS

The etiology and pathogenesis of ovarian cancer are still not fully understood. None of the so far proposed hypothesis on the development of OET can fully account for the epidemiologic and clinical findings in the context of reproductive factors and OET development. Further research approaches are warranted and need to put more weight on the clinical and genetical diversity of OET to yield a more detailed insight into their pathogenesis.

Gonadotropin signalling in epithelial ovarian cancer

Ovarian cancer is the most lethal of all gynecologic malignancies, although its aetiology remains poorly understood. A role for the gonadotropins, follicle-stimulating hormone (FSH) and luteinising hormone (LH), has been implicated in a variety of different aspects of ovarian cancer tumorigenesis, including cellular proliferation, migration and invasion. This review focuses on the latest advances in knowledge concerning signalling pathways and functional consequences of gonadotropin action, including changes in protein-, miRNA- and gene expression, in epithelial ovarian cancer cells.

Microenvironment and pathogenesis of epithelial ovarian cancer

Multiple genetic alterations play a role in the pathogenesis of ovarian cancer. Although many key proteins and pathways involved in ovarian carcinogenesis and metastasis have been discovered, knowledge of the early steps leading to malignancy remains poorly understood. This poor understanding stems from lack of data from early-stage cancers and absence of a well-established premalignant state universal to all ovarian cancer subtypes. Existing evidence suggests that ovarian cancers develop either through a stepwise mutation process (low-grade pathway), through genetic instability resulting in hastened metastasis (high-grade pathway), or more recently through what has been described as the "'fimbrial-ovarian' serous neoplasia theory." In this latter model, ovarian serous cancers evolve from premalignant lesions in the distal fallopian tube called tubal intraepithelial carcinoma. In this manuscript, we review key genetic and molecular changes that occur in cancer cell progression and suggest a model of ovarian cancer pathogenesis involving both tumor cell mutations and microenvironmental factors.

Peritoneal adhesion and angiogenesis in ovarian carcinoma are inversely regulated by hyaluronan: the role of gonadotropins

Ovarian carcinoma is the leading cause of death among gynecologic cancers. Although transformation of the outer ovarian epithelium was linked with ovulation, the disease is significantly more prevalent and severe in postmenopausal women. We postulated that menopause could augment ovarian cancer progression through the effects of gonadotropins on multifocal seeding to the mesothelial layer lining the peritoneum. This seeding is mediated by integrins as well as by CD44 interaction with hyaluronan (HA). Here, we report the effect of gonadotropins on HA synthesis and degradation and on peritoneal adhesion. A significant concentration- and time-dependent induction in expression levels of HA synthases (HASs) and hyaluronidases (Hyals) was observed in vitro on stimulation of human epithelial ovarian carcinoma cells by gonadotropins. Hormonal regulation of HA-mediated adhesion was manifested in vivo as well, by fluorescence microscopy of stained MLS multicellular tumor spheroids. The number of spheroids adhered to the mesothelium of ovariectomized CD-1 nude mice 9.5 hours after intraperitoneal insertion was significantly higher than in nonovariectomized mice. Inhibition of HA synthesis by 6-diazo-5-oxo-1-norleucine (DON) both in spheroids and ovariectomized mice significantly reduced the number of adhered spheroids. Thus, the change in the hormonal environment during menopause assists in HA-dependent adherence of ovarian cancer spheroids onto the peritoneum. However, HA is antiangiogenic and it can significantly suppress tumor progression. Accordingly, angiogenesis of the adhered spheroids was significantly elevated in DON-treated tumors. These results can explain the selective pressure that can lead to simultaneously increased tumor expression of both HASs and Hyals.

Gonadotropin-regulated lymphangiogenesis in ovarian cancer is mediated by LEDGF-induced expression of VEGF-C

The risk and severity of ovarian carcinoma, the leading cause of gynecologic malignancy death, are significantly elevated in postmenopausal women. Ovarian failure at menopause, associated with a reduction in estrogen secretion, results in an increase of the gonadotropic luteinizing hormone (LH) and follicle-stimulating hormone (FSH), suggesting a role for these hormones in facilitating the progression of ovarian carcinoma. The current study examined the influence of hormonal stimulation on lymphangiogenesis in ovarian cancer cells. In vitro stimulation of ES2 ovarian carcinoma cells with LH and FSH induced expression of vascular endothelial growth factor (VEGF)-C. In vivo, ovariectomy of mice resulted in activation of the VEGF-C promoter in ovarian carcinoma xenografts, increased VEGF-C mRNA level, and enhanced tumor lymphangiogenesis and angiogenesis. Seeking the molecular mechanism, we examined the role of lens epithelium-derived growth factor (LEDGF/p75) and the possible contribution of its putative target, a conserved stress-response element identified in silico in the VEGF-C promoter. Using chromatin immunoprecipitation, we showed that LEDGF/p75 indeed binds the VEGF-C promoter, and binding is augmented by FSH. A corresponding hormonally regulated increase in the LEDGF/p75 mRNA and protein levels was observed. Suppression of LEDGF/p75 expression using small interfering RNA, suppression of LH and FSH production using the gonadotropin-releasing hormone antagonist cetrorelix, or mutation of the conserved stress-response element suppressed the hormonally induced expression of VEGF-C. Overall, our data suggest a possible role for elevated gonadotropins in augmenting ovarian tumor lymphangiogenesis in postmenopausal women.

RGD-labeled USPIO inhibits adhesion and endocytotic activity of alpha v beta3-integrin-expressing glioma cells and only accumulates in the vascular tumor compartment

PURPOSE

To investigate the biologic effect of arginine-glycine-aspartic acid (RGD)-labeled ultrasmall superparamagnetic iron oxide (USPIO) (referred to as RGD-USPIO) on human umbilical vein endothelial cells (HUVECs), ovarian carcinoma (MLS) cells, and glioblastoma (U87MG) cells and on U87MG xenografts in vivo.

MATERIALS AND METHODS

All experiments were approved by the governmental review committee on animal care.USPIOs were coated with integrin-specific (RGD) or unspecific (arginine-alanine-aspartic acid [RAD]) peptides. USPIO uptake in HUVECs, MLS cells, and U87MG cells and in U87MG tumor xenografts was determined with T2 magnetic resonance (MR) relaxometry in 16 nude mice. Cells and tumors were characterized by using immunofluorescence microscopy. Trypan blue staining and lactate dehydrogenase assay were used to assess cytotoxicity. Statistical evaluation was performed by using a Mann-Whitney test or a linear mixed model with random intercept for the comparison of data from different experiments. Post hoc pairwise comparisons were adjusted according to a Tukey test.

RESULTS

HUVECs and MLS cells internalized RGD-USPIOs significantly more than unspecific probes. Controversially, U87MG cells accumulated RGD-USPIOs to a lesser extent than USPIO. Furthermore, only in U87MG cells, free RGD and alpha(v)beta(3) integrin-blocking antibodies strongly reduced endocytosis of nonspecific USPIOs. This was accompanied by a loss of cadherin-dependent intercellular contacts, which could not be attributed to cell damage. In U87MG tumors, RGD-USPIO accumulated exclusively at the neovasculature but not within tumor cells. The vascular accumulation of RGD-USPIO caused significantly higher changes of the R2 relaxation rate of tumors than observed for USPIO.

CONCLUSION

In glioma cells with unstable intercellular contacts, inhibition of alpha(v)beta(3) integrins by antibodies and RGD and RGD-USPIO disintegrated intercellular contacts and reduced endocytotic activity, illustrating the risk of inducing biologic effects by using molecular MR probes.

Harnessing competing endocytic pathways for overcoming the tumor-blood barrier: magnetic resonance imaging and near-infrared imaging of bifunctional contrast media

Ovarian cancer is the most lethal gynecologic malignancy, often diagnosed at advanced stage leading to poor prognosis. In the study reported here, magnetic resonance imaging and near-infrared reflectance imaging were applied for in vivo analysis of two competing endocytic pathways affecting retention of bifunctional daidzein-bovine serum albumin (BSA)-based contrast media by human epithelial ovarian carcinoma cells. Suppression of caveolae-mediated uptake using nystatin or by BSA competition significantly enhanced daidzein-BSA-GdDTPA/CyTE777 uptake by tumor cells in vitro. In vivo, perivascular myofibroblasts generated an effective perivascular barrier excluding delivery of BSA-GdDTPA/CyTE777 to tumor cells. The ability to manipulate caveolae-mediated sequestration of albumin by perivascular tumor myofibroblasts allowed us to effectively overcome this tumor-stroma barrier, increasing delivery of daidzein-BSA-GdDTPA/CyTE777 to the tumor cells in tumor xenografts. Thus, both in vitro and in vivo, endocytosis of daidzein-BSA-GdDTPA/CyTE777 by ovarian carcinoma cells was augmented by albumin or by nystatin. In view of the cardinal role of albumin in affecting the availability and pharmacokinetics of drugs, this approach could potentially also facilitate the delivery of therapeutics and contrast media to tumor cells.

Luteinizing hormone-induced up-regulation of ErbB-2 is insufficient stimulant of growth and invasion in ovarian cancer cells

The effects of luteinizing hormone (LH), a gonadotropic hormone implicated in the development of ovarian cancer, are mediated by specific binding to its G protein-coupled receptor, the LH receptor (LHR). Activated LHR initiates second messenger responses, including cyclic AMP (cAMP) and inositol phosphate. Because cAMP increases expression of ErbB-2, a receptor tyrosine kinase whose overexpression in cancers correlates with poor survival, we hypothesized that LH may regulate ErbB-2 expression. Cell surface LHR expression in stable transformants of the ErbB-2-overexpressing ovarian cancer cell line SKOV3 was confirmed by PCR and whole-cell ligand binding studies. Second messenger accumulation in the LHR-expressing cells confirmed signaling through Gs and Gq. Western blots of total protein revealed that LHR introduction up-regulated ErbB-2 protein expression 2-fold and this was further up-regulated in a time- and dose-dependent manner in response to LH. Forskolin and 8Br-cAMP also up-regulated ErbB-2 in both LHR-expressing and mock-transfected cells, indicating that regulation of ErbB-2 is a cAMP-mediated event. Kinase inhibitor studies indicated the involvement of protein kinase A-mediated, protein kinase C-mediated, epidermal growth factor receptor-mediated, and ErbB-2-mediated mechanisms. The LH-induced up-regulation of ErbB-2 was insufficient to overcome the negative effects of LH on proliferation, invasion, and migration. A molecular signature for this nonaggressive phenotype was determined by Taqman array to include increased and decreased expression of genes encoding adhesion proteins and metalloproteinases, respectively. These data establish a role for LH and LHR in the regulation of ErbB-2 expression and suggest that, in some systems, ErbB-2 up-regulation alone is insufficient in producing a more aggressive phenotype.

Early Events in the Pathogenesis of Epithelial Ovarian Cancer

Ovarian carcinogenesis, as in most cancers, involves multiple genetic alterations. A great deal has been learned about proteins and pathways important in the early stages of malignant transformation and metastasis, as derived from studies of individual tumors, microarray data, animal models, and inherited disorders that confer susceptibility. However, a full understanding of the earliest recognizable events in epithelial ovarian carcinogenesis is limited by the lack of a well-defined premalignant state common to all ovarian subtypes and by the paucity of data from early-stage cancers. Evidence suggests that ovarian cancers can progress both through a stepwise mutation process (low-grade pathway) and through greater genetic instability that leads to rapid metastasis without an identifiable precursor lesion (high-grade pathway). In this review, we discuss many of the genetic and molecular disorders in each key process that is altered in cancer cells, and we present a model of ovarian pathogenesis that incorporates the role of tumor cell mutations and factors in the host microenvironment important to tumor initiation and progression.

In vivo imaging of the systemic recruitment of fibroblasts to the angiogenic rim of ovarian carcinoma tumors

Tumor-associated stroma, in general, and tumor fibroblasts and myofibroblasts, in particular, play a role in tumor progression. We previously reported that myofibroblast infiltration into implanted ovarian carcinoma spheroids marked the exit of tumors from dormancy and that these cells contributed to vascular stabilization in ovarian tumors by expression of angiopoietin-1 and angiopoietin-2. Ex vivo labeling of fibroblasts with either magnetic resonance or optical probes rendered them detectable for in vivo imaging. Thus, magnetic resonance imaging (MRI) follow-up was feasible by biotin-bovine serum albumin-gadolinium diethylenetriaminepentaacetic acid or iron oxide particles, whereas labeling with near-IR and fluorescent vital stains enabled in vivo visualization by near-IR imaging and two-photon microscopy. Using this approach, we show here that prelabeled fibroblasts given i.p. to CD-1 nude mice can be followed in vivo by MRI and optical imaging over several days, revealing their extensive recruitment into the stroma of remote s.c. MLS human epithelial ovarian carcinoma tumors. Two-photon microscopy revealed the alignment of these invading fibroblasts in the outer rim of the tumor, colocalizing with the angiogenic neovasculature. Such angiogenic vessels remained confined to the stroma tracks within the tumor and did not penetrate the tumor nodules. These results provide dynamic evidence for the role of tumor fibroblasts in maintenance of functional tumor vasculature and offer means for image-guided targeting of these abundant stroma cells to the tumor as a possible mechanism for cellular cancer therapy.

Gonadotropins and ovarian cancer

Ovarian epithelial cancer (OEC) accounts for 90% of all ovarian cancers and is the leading cause of death from gynecological cancers in North America and Europe. Despite its clinical significance, the factors that regulate the development and progression of ovarian cancer are among the least understood of all major human malignancies. The two gonadotropins, FSH and LH, are key regulators of ovarian cell functions, and the potential role of gonadotropins in the pathogenesis of ovarian cancer is suggested. Ovarian carcinomas have been found to express specific receptors for gonadotropins. The presence of gonadotropins in ovarian tumor fluid suggests the importance of these factors in the transformation and progression of ovarian cancers as well as being prognostic indicators. Functionally, there is evidence showing a direct action of gonadotropins on ovarian tumor cell growth. This review summarizes the key findings and recent advances in our understanding of these peptide hormones in ovarian cancer development and progression and their role in potential future cancer therapy. We will first discuss the supporting evidence and controversies in the "gonadotropin theory" and the use of animal models for exploring the involvement of gonadotropins in the etiology of ovarian cancer. The role of gonadotropins in regulating the proliferation, survival, and metastasis of OEC is next summarized. Relevant data from ovarian surface epithelium, which is widely believed to be the precursor of OEC, are also described. Finally, we will discuss the clinical applications of gonadotropins in ovarian cancer and the recent progress in drug development.

Gonadotropin and its role in the β-catenin/T-cell factor signaling pathway

Gonadotropins, follicle-stimulating hormone and luteinizing hormone are key regulators in ovarian function, acting in an endocrine manner to regulate gametogenesis and steroidogenesis. In addition to normal tissue, gonadotropin receptors have also been demonstrated in ovarian carcinoma cell lines and primary tumors, suggesting that the gonadotropins may play a role in the pathophysiology of ovarian cancer. Thus, understanding mechanisms involved in signaling transduction by the gonadotropin receptors are of considerable interest and potential significance. In the ovary, gonadotropins initiate their cellular responses by binding to their G-protein-coupled receptors and activation of specific downstream intracellular effectors and signal pathways, including those of protein kinases A and C and mitogen-activated protein kinase. Recently, gonadotropins were shown to stimulate nuclear accumulation of β-catenin, which controls lymphoid-enhancing factor/T-cell factor family-sensitive gene expression. β-catenin has a pivotal function in the control of cell fate. The ability of gonadotropins to regulate β-catenin provides a new dimension of knowledge linking pituitary hormones to the β-catenin signaling in normal ovarian physiology and demonstrating how its dysregulation can contribute to the development of ovarian cancer.

Kinetic analysis of hyaluronidase activity using a bioactive MRI contrast agent

One of the attractions of molecular imaging using 'smart' bioactive contrast agents is the ability to provide non-invasive data on the spatial and temporal changes in the distribution and expression patterns of specific enzymes. The tools developed for that aim could potentially also be developed for functional imaging of enzyme activity itself, through quantitative analysis of the rapid dynamics of enzymatic conversion of these contrast agents. High molecular weight hyaluronan, the natural substrate of hyaluronidase, is a major antiangiogenic constituent of the extracellular matrix. Degradation by hyaluronidase yields low molecular weight fragments, which are proangiogenic. A novel contrast material, HA-GdDTPA-beads, was designed to provide a substrate analog of hyaluronidase in which relaxivity changes are induced by enzymatic degradation. We show here a first-order kinetic analysis of the time-dependent increase in R(2) as a result of hyaluronidase activity. The changes in R(2) and the measured relaxivity of intact HA-GdDTPA-beads (r(2B)) and HA-GdDTPA fragments (r(2D)) were utilized for derivation of the temporal drop in concentration of GdDTPA in HA-GdDTPA-beads as the consequence of the release of HA-GdDTPA fragments. The rate of dissociation of HA-GdDTPA from the beads showed typical bell-shaped temperature dependence between 7 and 36 degrees C with peak activity at 25 degrees C. The tools developed here for quantitative dynamic analysis of hyaluronidase activity by MRI would allow the use of activation of HA-GdDTPA-beads for the determination of the role of hyaluronidase in altering the angiogenic microenvironment of tumor micro metastases.

Role of endocrine and growth factors on the ovarian surface epithelium

Epithelial ovarian cancer is a highly fatal disease for which prevention strategies have been limited; in part because of our poor understanding of the underlying biology of its precursor, the ovarian surface epithelium (OSE). The OSE is a single layer of flat-to-cuboidal mesothelial cells that covers the surface of the ovary. Despite its inconspicuous appearance in vivo, it is believed that OSE cells actively participate in the cyclical ovulatory rupture and repair process. The continuous rupture of the OSE at ovulation and the subsequent proliferation to repair the wound renders the cells susceptible to genetic damage and malignant transformation. As the ovary is a rich source of multiple hormones, and normal OSE and ovarian carcinomas secrete and have receptors for hormones, growth factors and cytokines, these factors are strong candidates to regulate normal OSE physiology and the transformation and progression of ovarian cancers. In particular, alterations of hormone/growth factor production and receptor expression are common in ovarian tumors. This review summarizes the current knowledge in the field of endocrinology and its relationship to the biology and pathology of the OSE.

Molecular imaging of angiogenesis

Angiogenesis (the growth of new blood vessels) is a complex multistep process that involves multiple cell types, numerous growth factors, and complex regulatory checks and balances. Tight control of vascular remodeling evolved to ensure stability of the vasculature while maintaining the body's ability to rapidly mount an angiogenic response requiring a high degree of plasticity. Angiogenesis is critical not only for physiological development, but also for the progression of pathologies, and is thus a target for therapeutic intervention. The importance of the process coupled with the ease of access for delivery of contrast agents makes the vasculature at large, and angiogenesis in particular, a favorable target of functional and molecular imaging. Recent developments in molecular imaging tools have expanded our views to encompass many components of the process. Functional imaging of blood volume, vessel permeability, and vasoreactivity is complemented by novel contrast agents that reveal specific targets on endothelial cells. Methods have been developed to label vascular cells so as to track their recruitment to sites of angiogenesis, and new "smart" contrast agents have been designed to reveal the activity of enzymatic reactions in altering the extracellular matrix (ECM) during angiogenesis.

Endocrine signaling in ovarian surface epithelium and cancer

Ovarian cancer is the sixth most common cancer and the fifth leading cause of cancer-related death among women in developed countries. Greater than 85% of human ovarian cancer arises within the ovarian surface epithelium (OSE), with the remainder derived from granulosa cells or, rarely, stroma or germ cells. The pathophysiology of ovarian cancer is the least understood among all major human malignancies because of a poor understanding of the aetiological factors and mechanisms of ovarian cancer progression. There is increasing evidence suggesting that several key reproductive hormones, such as GnRH, gonadotrophins and sex steroids, regulate the growth of normal OSE and ovarian cancer cells. The objective of this review was to highlight the effects of these endocrine factors on ovarian cancer cell growth and to summarize the signalling mechanisms involved in normal human OSE and its neoplastic counterparts.

Premature menopause in patients with BRCA1 gene mutation

This study was undertaken with regard to the gonadotropin theory of ovarian cancer advocated in the literature and was designed to disclose specific features of ovarian morphology in carriers of the BRCA1 gene mutation. We enrolled 171 patients and divided them into two groups: A (n=90)--operated for breast cancer (30 patients with and 60 without the BRCA1 mutation); B (n=81)--with the BRCA1 mutation qualified for preventive adnexectomy. According to the authors' classification described herein, some patients without the BRCA1 mutation retained "signs of estrogenization" in menopausal ovaries, revealing the role of estrogens as a factor promoting mammary carcinogenesis in these patients. A tendency to premature menopause was observed in BRCA1 mutation carriers of groups A and B as evidenced by the final menorrhea appearing at a younger age and almost total absence of "signs of estrogenization" in menopausal ovaries. It is concluded from these findings that earlier menopause in carriers of the BRCA1 mutation is associated with hypergonadotropic activity and may predispose to ovarian cancer at younger age.

Gonadotropins activate proteolysis and increase invasion through protein kinase A and phosphatidylinositol 3-kinase pathways in human epithelial ovarian cancer cells

Despite evidence that gonadotropins may facilitate peritoneal metastasis of ovarian cancer by increasing cell adhesion, the action and molecular mechanism of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in ovarian cancer invasion is not well characterized. In the present study, we investigated the effects of FSH and LH on the invasive activity and the expression of metastasis-related proteinases in human epithelial ovarian cancer by Western blot, zymography, reverse transcription-PCR (RT-PCR), ELISA, and Boyden chamber assay. Treatment with FSH or LH (10, 100, or 1,000 ng/mL) significantly increased the invasion of ovarian cancer cell lines, including BG-1, CaOV-3, and SKOV-3 cells but not OVCAR-3 cells. In addition, treatment of SKOV-3 cells with FSH or LH (100 or 1,000 ng/mL) enhanced the expression and activation of matrix metalloproteinases (MMP-2 and MMP-9) as shown by RT-PCR, gelatin zymography, and ELISA. Pretreatment with [(2R)-2-(hydroxamido-carbonylmethyl)-4-methylpentanoyl]-l-tryptophan methylamide (10 micromol/L), a total MMP inhibitor, and 3-(4-phenoxyphenylsulfonyl)-propylthiirane (20 micromol/L), a specific gelatinase inhibitor, neutralized the proinvasive effect of gonadotropins in SKOV-3 cells. In addition, the secretion of tissue inhibitor of metalloproteinases (TIMP-1 and TIMP-2) and plasminogen activator inhibitor-1 was significantly decreased by FSH and LH (100 or 1,000 ng/mL). We further showed that gonadotropins induced an increase in SKOV-3 invasiveness via the activation of protein kinase A (PKA) and phosphatidylinositol 3-kinase (PI3K) signaling pathways. Taken together, these results suggest that gonadotropins may contribute to ovarian cancer metastasis via activation of proteolysis and increase in invasion through the PKA and PI3K pathways.

Gonadotropins and ovarian carcinogenesis: a new era of basic research and its clinical implications

The possible relationship between gonadotropins and ovarian carcinoma development has received much attention, and in recent years, great progress has been made in basic and epidemiologic research about this issue. Gonadotropins sensitivity in the ovarian surface epithelium (OSE) and in a subset of ovarian carcinomas has been established in vivo and in vitro. Gonadotropins have been shown to induce various biologic actions in the OSE and ovarian carcinoma cells, such as changes in cell proliferation, apoptosis, cell adhesion, and chemosensitivity. These basic studies strongly suggest that gonadotropins are involved in the development and progression of ovarian carcinoma. In contrast, although earlier studies showed a significant risk of infertility therapy for ovarian carcinoma development, subsequent studies reported only slightly increased or no significant increased risk of gonadotropin stimulation and/or assisted reproductive technologies for ovarian carcinoma development. Therefore, the association between ovarian stimulation and ovarian carcinoma remains controversial. Nevertheless, since development of ovarian carcinoma in infertile women during infertility treatment is a serious concern for gynecologists, this review also covers important points for clinical practice, especially the issue of early detection of ovarian carcinoma.

Magnetic resonance imaging visualization of hyaluronidase in ovarian carcinoma

Hyaluronan, a high molecular weight, negatively charged polysaccharide, is a major constituent of the extracellular matrix. High molecular weight hyaluronan is antiangiogenic, but its degradation by hyaluronidase generates proangiogenic breakdown products. Thus, by expression of hyaluronidase, cancer cells can tilt the angiogenic balance of their microenvironment. Indeed, hyaluronidase-mediated breakdown of hyaluronan correlates with aggressiveness and invasiveness of ovarian cancer metastasis and with tumor angiogenesis. The goal of this work was to develop a novel smart contrast material for detection of hyaluronidase activity by magnetic resonance imaging (MRI). Gadolinium-diethylenetriaminepentaacetic acid (GdDTPA) covalently linked to hyaluronan on the surface of agarose beads showed attenuated relaxivity. Hyaluronidase, either purified from bovine testes or secreted by ES-2 and OVCAR-3 human epithelial ovarian carcinoma cells, activated the hyaluronan-GdDTPA-beads by rapidly altering the R1 and R2 relaxation rates. The change in relaxation rates was consistent with the different levels of biologically active hyaluronidase secreted by those cells. Hyaluronan-GdDTPA-beads were further used for demonstration of MRI detection of hyaluronidase activity in the proximity of s.c. ES-2 ovarian carcinoma tumors in nude mice. Thus, hyaluronan-GdDTPA-beads could allow noninvasive molecular imaging of hyaluronidase-mediated tilt of the peritumor angiogenic balance.

Role of VEGF and CD44v6 in differentiating benign from malignant ascites

AIM: To detect the vascular endothelial growth factor (VEGF) and soluble splice variant 6 of CD44 (sCD44v6) levels in ascites and to explore their role in differentiating benign from malignant ascites.

METHODS: Cirrhotic ascites (n = 36), tuberculosis ascites (n = 8) and malignant ascites (n = 23) were collected and studied. Concentrations of soluble VEGF and sCD44v6 in various kinds of ascites (n = 67) were measured using a sandwich enzyme-linked immunoadsorbent assay.

RESULTS: VEGF and sCD44v6 levels in malignant ascites were 640.74 ± 264.81 pg/mL and 89.22 ± 38.20 ng/mL, respectively, both of which were significantly higher than those in cirrhotic ascites and tuberculous ascites (q = 18.98, 11.89 and q = 8.92, 5.09; P < 0.01). However, the levels of VEGF and sCD44v6 in cirrhotic and tuberculous ascites had no significant difference (q = 0.48, 0.75; P > 0.05). Furthermore, VEGF levels in malignant ascites in patients with ovarian cancer were higher than those with gastric and colon cancer (q = 5.03, 6.79; P < 0.01, respectively). But differences of VEGF levels between gastric and colon cancer were not significant (q = 1.90, P > 0.05). Whereas, sCD44v6 levels in malignant ascites from patients with ovarian, gastric and colon cancer had no significant difference (q = 0.06, 0.91, 0.35; P > 0.05, respectirely). In comparison with cirrhotic and tuberculous ascites, when the upper limit of its VEGF mean levels 119.44 pg/mL (70.90 ± 48.54) and sCD44v6 mean levels 63.59 ng/mL (44.42 ± 19.17) was taken as the minimum cutoff limit, the sensitivity and specificity of VEGF and sCD44v6 of this assay to the diagnos is of malignant ascites were 91.3%, 90.9% and 73.9%, 88.7% respectively.

CONCLUSION: Elevated levels of VEGF and sCD44v6 may be useful in differential diagnosis of benign and malignant ascites.

The role of angiogenesis, vascular maturation, regression and stroma infiltration in dormancy and growth of implanted MLS ovarian carcinoma spheroids

MLS ovarian epithelial carcinoma multicellular spheroids xenografted subcutaneously in CD-1 nude mice displayed growth delay, or dormancy, of up to 52 days. In the study reported here, implanted MLS spheroids were used for testing the role of angiogenesis and vascular maturation in triggering the initiation of tumor progression. The kinetics and impact of neovascular maturation and functionality, in dormancy, and growth of MLS spheroid xenografts were studied noninvasively by BOLD contrast MRI. MR data were supported by histologic staining for biotinylated albumin as a blood pool marker and alpha-smooth muscle actin (alpha-SMA) as marker for perivascular mural cells. Although the tumor periphery showed higher levels of total and mature vasculature than normal skin, the fraction of mature out of the total vessels as detected by MRI vascular maturation index (VMI(MRI)) was significantly lower in the tumor both before and after tumor exit from dormancy. The neovasculature induced by the implanted spheroid was unstable and showed cycles of vessel growth and regression. Surprisingly, this instability was not restricted to the immature vessels, but rather included also regression of mature vessels. During dormancy, neovasculature was predominantly peripheral with no infiltration into the implanted spheroid. Infiltration of alpha-SMA positive stroma cells into the spheroid was associated with functional vascularization and tumor growth. Thus, stroma infiltration and vascular maturation are an important checkpoint linking the angiogenic switch with initiation of tumor progression.