Promising molecular targets in ovarian cancer

Proline-rich protein 11 overexpression is associated with a more aggressive phenotype and poor overall survival in ovarian cancer patients

BACKGROUND

The proline-rich protein 11 (PRR11) is a newly identified oncogene associated with a poor prognosis in several human cancers. Nonetheless, research on its role in ovarian cancer (OC) remains largely understudied. Therefore, this study aims to evaluate the expression levels of PRR11 protein and its role in human ovarian cancer.

METHODS

Immunohistochemistry analysis was used to evaluate the expression levels of PRR11 protein in human samples obtained from 49 patients diagnosed with OC and subjected to curative surgery in the First Affiliated Hospital of Wenzhou Medical University between 2007 and 2015.

RESULTS

In total, 57.1% of the primary OC tumor tissue evaluated demonstrated overexpression of PRR11. Meanwhile, the survival analysis showed that the overall survival (OS) of patients presenting overexpression of PRR11 was significantly lower than the OS of the patients with negative PRR11. In subsequent experiments, it was found that silencing the expression of PRR11 expression inhibited the proliferation of tumor cells and the migration of cells in vitro. Further, cells subjected to PRR11 knockdown exhibited a decrease in tumor growth in vivo. The downregulation of PRR11 was coupled with a decrease in N-cadherin and downregulation in the expression of early growth response protein 1 (EGR1).

CONCLUSIONS

The findings suggest that PRR11 might be considered as a potential target for prognostic assessment and gene therapy strategies for patients diagnosed with OC.

Anti-tumorigenic and Platinum-Sensitizing Effects of Apolipoprotein A1 and Apolipoprotein A1 Mimetic Peptides in Ovarian Cancer

Objective: Apolipoprotein A1 (ApoA1) is remarkably decreased in serum and ovarian tissues of ovarian cancer patients. ApoA1 and ApoA1 mimetic peptides can sequestrate pro-inflammatory phospholipids, some of which are known to activate a variety of oncogenic pathways. Besides, more intrinsic anti-tumorigenic properties, independent from interaction with lipids, have also been described for ApoA1. We aimed to disclose the effects of ApoA1 and a mimetic peptide on the malignant phenotype of ovarian cancer cells, particularly regarding cell viability, invasiveness and platinum sensitization. Methods: Cells viability was assessed by MTS assay. Extracellular matrix invasion was assessed by transwell and spheroid invasion assays. Western blotting was performed to evaluate the effect of test compounds on intracellular pathways. Sensitization assays were performed in vitro and in the biologically relevant in ovo chorioallantoic membrane model. Results: Both ApoA1 and the mimetic peptide, at a concentration of 100 μg/mL, were able to decrease the viability of SKOV3, CAOV3, and OVCAR3 cells (p < 0.05). The peptide at this concentration was not able to affect the viability of immortalized non-neoplastic ovarian cells (p > 0.05). ApoA1 decreased SKOV3 cells invasiveness at 300 μg/mL after 72 and 96 h of exposure (p < 0.05), while the ApoA1 mimetic peptide prevented cell invasion at 50 and 100 μg/mL (p < 0.01). Treatment with 100 μg/mL of ApoA1 mimetic peptide decreased Akt phosphorylation in SKOV3 cells (p < 0.01). Accordingly, treatment with increasing concentrations of the peptide sensitized SKOV3, OVCAR3 and CAOV3 cells to cisplatin. This synergistic effect was observed both in vitro and in ovo. Conclusions: These results support the role of ApoA1 and ApoA1 mimetics as suppressors of ovarian tumorigenesis and as chemo-sensitising agents.

BRCA1 deficiency increases the sensitivity of ovarian cancer cells to auranofin

Auranofin, a thioredoxin reductase inhibitor and an anti-rheumatic drug is currently undergoing phase 2 clinical studies for repurposing to treat recurrent epithelial ovarian cancer. Previous studies have established that auranofin exerts its cytotoxic activity by increasing the production of reactive oxygen species (ROS). Breast cancer 1, early onset (BRCA1) is a DNA repair protein whose functional status is critical in the prognosis of ovarian cancer. Apart from its key role in DNA repair, BRCA1 is also known to modulate cellular redox homeostasis by regulating the stability of anti-oxidant transcription factor, nuclear factor erythroid 2-related factor 2 (Nrf2) via direct protein-protein interaction. However, it is currently unknown whether BRCA1 modulates the sensitivity of ovarian cancer cells to auranofin. Here we report that BRCA1-depleted cells exhibited increased DNA double strand breaks (DSBs) and decreased clonogenic cell survival upon auranofin treatment. Interestingly, auranofin induced the expression of Nrf2 in BRCA1-depleted cells suggesting its regulation independent of BRCA1. Furthermore, anti-oxidant agent, N-acetyl cysteine (NAC) protected BRCA1-depleted cells from DNA damage and apoptosis induced by auranofin. Our study suggests that accumulated lethal DSBs resulting from the oxidative damage render BRCA1 deficient cells more sensitive to auranofin despite the activation of Nrf2.

The prognostic value of dividing epithelial ovarian cancer into type I and type II tumors based on pathologic characteristics

OBJECTIVE

To investigate the prognostic significance of dividing epithelial ovarian cancer (EOC) in type I and type II tumors based on pathologic variables.

METHODS

We used the Danish Gynecologic Cancer Database to identify all patients diagnosed with EOC from 2005 to 2012. Information on histologic type and grade were used to classify tumors as either type I or type II. Death, and several prognostic factors were used in the multivariate Cox regression, and Landmark analysis was used to estimate hazard ratios of all-cause mortality.

RESULTS

Among 2660 patients diagnosed with EOC, 735 were categorized as type I tumors, and 1925 as type II tumors. Patients with type II EOC were more frequently diagnosed in late FIGO stages (stages III-IV) than patients with type I EOC (78.1% vs. 32.1% respectively; P<0.001). Time dependent multivariate Cox analysis, adjusted for known prognostic variables, showed no significant difference in survival within the first two years after diagnosis, however, after 730days of follow-up a significantly increased overall survival for type I tumors was observed (hazard ratio 1.72, 95% confidence interval: 1.28-2.31, P<0.001). Similarly the Landmark analysis for survival confirmed the increased overall survival for type I tumors after two years of follow-up (hazard ratio: 1.85, 95% confidence interval: 1.35-2.54, P<0.001).

CONCLUSION

Classification of EOC in type I and type II tumors based on pathologic variables was associated with an increased risk of death for type II tumors after two years of follow-up, while no increased risk was seen during the first two years of follow-up.

Targeting JAK1/STAT3 signaling suppresses tumor progression and metastasis in a peritoneal model of human ovarian cancer

JAK/STAT3 is one of the major signaling pathways that is aberrantly activated in ovarian cancer and associated with tumor progression and poor prognosis in patients with ovarian cancer. In this study, we evaluated the therapeutic potential of targeting JAK/STAT3 signaling in ovarian cancer using a peritoneal dissemination mouse model. We developed this mouse model by injecting a metastatic human ovarian cancer cell line, SKOV3-M-Luc, into the peritoneal cavity of immunodeficient mice. This model displayed a phenotype similar to late-stage ovarian cancer, including extensive peritoneal metastasis and ascites production. The constitutive activation of STAT3 in human ovarian cancer cells appeared to be mediated by an autocrine cytokine loop involving the IL6 family of cytokines and JAK1 kinase. shRNA-mediated knockdown of JAK1 or STAT3 in ovarian cancer cells led to reduced tumor growth, decreased peritoneal dissemination, and diminished ascites production, suggesting a critical role of STAT3 in ovarian cancer progression. Similar results were obtained when a small-molecule inhibitor (JAKi) of the JAK1 kinase was used to treat ovarian cancer in this model. In addition, we found that the expression level of IL6 was correlated with activation of STAT3 in ovarian cancer cells both in vitro and in vivo, suggesting a potential application of IL6 as a biomarker. Altogether, our results demonstrate that targeting JAK1/STAT3, using shRNA knockdown or a small-molecule inhibitor, effectively suppressed ovarian tumor progression and, therefore, could be a potential novel therapeutic approach for treating advanced ovarian cancer.

Disulfiram/copper causes redox-related proteotoxicity and concomitant heat shock response in ovarian cancer cells that is augmented by auranofin-mediated thioredoxin inhibition

A valuable strategy to develop new therapeutic options for a variety of diseases has been the identification of new targets and applications for already approved drugs, the so-called drug repositioning. Recurrent ovarian cancer is a nearly incurable malignancy for which new and effective treatments are urgently needed. The alcohol-deterring drug disulfiram has been shown to cause preferential cell death in a variety of cancer cells. In this study, it is shown that disulfiram mediates effective cell death in ovarian cancer cells by promoting a pro-oxidative intracellular environment in a copper-dependent mechanism. Within few hours of application, disulfiram caused irreversible cell damage associated with pronounced induction of the inducible heat shock proteins HSP70, HSP40, and HSP32. The small heat shock protein HSP27 was found to be covalently dimerized via oxidized disulfide bonds and precipitated in para-nuclear protein aggregates. Simultaneous inhibition of the cellular thioredoxin system by auranofin further enhanced the cytotoxic effect of disulfiram. These data indeed indicate that the combination of two approved drugs, the anti-alcoholic disulfiram and the anti-rheumatic auranofin, may be of interest for the treatment of recurrent and genotoxic drug-resistant ovarian cancer by inducing a proteotoxic cell death mechanism.

Investigational agents in development for the treatment of ovarian cancer

Although significant success has been achieved in the treatment of advanced and recurrent ovarian cancer, there is clearly room for improvement. The use of targeted agents in this patient population has the promise to provide improved survival and quality of life. There are a myriad of relevant pathways under exploration in all settings of ovarian cancer. Clinical trial data are accumulating for antiangiogenic therapy, including vascular endothelial growth factor (VEGF)-specific inhibitors and multiple angiogenic signaling target inhibitors, as well as poly-ADP-ribose polymerase (PARP) inhibitors. Other types of tumorigenic pathway inhibitors, including those that target phosphatidylinositol-3-kinase (PI3K), mammalian target of rapamycin (mTOR), protein kinase B (AKT), Src, folate receptor alpha, and insulin-like growth factor-1 receptor (IGF-1R) pathways are in earlier phases of development for ovarian cancer. Attempts to target the epidermal growth factor receptor (EGFR) of ovarian tumors have been met with limited success; however, newer agents that inhibit this pathway show promise. Finally, with recognition of the role of Wee-1 in p53-deficient tumors, an inhibitor of this tyrosine kinase is being evaluated in recurrent ovarian cancer. The logistical challenge is to determine the optimal timing and proper combinations of novel agents independently as well as concomitantly with conventional chemotherapeutics. Reported results have been modest; however, our growing understanding of these pathways will be potentially reflected in greater impact on response and survival.

LY294002 and metformin cooperatively enhance the inhibition of growth and the induction of apoptosis of ovarian cancer cells

BACKGROUND

The phosphoinositide 3 kinase (PI3K)/v-akt murine thymoma viral oncogene homolog (AKT)/mammalian target of rapamycin (mTOR) pathway is frequently aberrantly activated in ovarian cancer and confers the chemoresistant phenotype of ovarian cancer cells. LY294002 (PI3K inhibitor) and metformin (5'-adenosine monophosphate [AMP]-activated protein kinase [AMPK] activator) are 2 drugs that were known to inhibit mTOR expression through the AKT-dependent and AKT-independent pathways, respectively. In this study, we explored the effectiveness of LY294002 and metformin in combination on inhibition of ovarian cancer cell growth.

METHODS

Western blotting was used to detect the changes of PI3K/AKT/mTOR and AMPK/acetyl-CoA carboxylase (ACC) signaling activities, cell cycle control, and apoptosis. Cell growth was evaluated by cell proliferation, colony formation, and soft agar assays. Flow cytometry was used to study cell cycle distribution and cell death upon drug treatment.

RESULTS

Our study showed that LY294002 and metformin in combination could simultaneously enhance the repression of the PI3K/AKT/mTOR pathway and the activation of the AMPK/ACC pathway. The downstream target of AKT and AMPK, mTOR, was cooperatively repressed when the drugs were used together. The cell cycle regulatory factors, p53, p27, and p21, were up-regulated. On the other hand, caspase 3 and poly (ADP-ribose) polymerase activities involved in apoptosis were also activated. Cell growth assays indicated that LY294002 and metformin could effectively inhibit ovarian cancer cell growth. Flow cytometry analysis showed that the treatment of the 2 drugs mentioned above induced cell cycle arrest at G1 phase and increased sub-G1 apoptotic cells.

CONCLUSION

The combinational use of LY294002 and metformin can enhance inhibition of the growth and induction of the apoptosis of ovarian cancer cells. Our results may provide significant insight into the future therapeutic regimens in ovarian cancer.

Biologic therapies and personalized medicine in gynecologic malignancies

Through advances in human genomic sequencing, the unique molecular biology that predisposes certain individuals to either health or disease has now been illuminated. Although many malignancies behave similarly on a phenotypic level, biologically there exist multiple layers of interconnected molecular and cellular pathways that may make each patient’s disease significantly more unique than previously appreciated. In gynecologic oncology, the most progress in developing targeted biologics has been in the treatment of ovarian cancers. Future investigations will see further development in endometrial and cervical cancers. Technology such as whole genome sequencing can theoretically identify the individual tumor’s genetic profile; however, identifying the priority pathways for therapeutic interventions and subsequent complex interactions remains a significant challenge. New therapeutic technologies such as siRNA and immune modulators will also play a promising role in the movement toward individualized therapies. It is hoped that the identification and use of targeted agents will lead to individualized care that in turn will lead to significantly improved outcomes manifested by more cures and better quality of life through amelioration of toxicities.

Minocycline inhibits growth of epithelial ovarian cancer

OBJECTIVE

These studies were designed to determine whether minocycline inhibits ovarian cancer growth in vitro and in vivo and the molecular mechanisms involved.

MATERIALS AND METHODS

The effect of minocycline on ovarian cancer cell proliferation, cell cycle progression and apoptosis was assessed using human ovarian cancer cell lines OVCAR-3, SKOV-3 and A2780. Then, the capacity of minocycline to inhibit growth of OVCAR-3 xenografts in female nude mice was examined.

RESULTS

Minocycline inhibited cell proliferation and colony formation, down-regulated cyclins A, B and E leading to arrest of cells in the G(0) phase of the cycle and suppression of DNA synthesis. Furthermore, exposure of these cells to minocycline led to DNA laddering, activation of caspase-3 and cleavage of PARP-1. In nude mice bearing sub-cutaneous tumors, minocycline suppressed tumor proliferation index, angiogenesis and tumor growth.

CONCLUSION

These findings provide the initial basis for further evaluation of minocycline in the treatment of ovarian cancer.

Iris Nertschinskia ethanol extract differentially induces cytotoxicity in human breast cancer cells depending on AKT1/2 activity

Recently, we reported that an ethanol extract of Iris nertschinskia induces p53-dependent apoptosis in the MCF7 human breast cancer cell line. However, the detailed mechanisms were not fully explored. Here, we demonstrate another aspect of the activity of I. nertschinskia in breast cancer cells. We compared the response to an ethanol extract of I. nertschinskia in two different human breast cancer cell lines, Hs578Tand MDA-MB231, respectively with relatively low and high AKT1/2 activity by trypan blue exclusion assay and FACS analysis. Knockdown of endogenous AKT1 or AKT2 in breast cancer cells by RNA interference determined the sensitivity to I. nertschinskia ethanol extract compared to control cells. The I. nertschinskia ethanol extract induced cell death in a manner that depended on the level of phosphorylated AKT1/2 protein and was associated with a significant increase in the sub-G1 cell population, indicative of apoptosis. Our results indicate that an ethanol extract of I. nertschinskia differentially induces cell death in breast cancer cells depending on their level of phosphorylated AKT1/2.

Role of histological type on surgical outcome and survival following radical primary tumour debulking of epithelial ovarian, fallopian tube and peritoneal cancers

Background:

To assess the clinical impact of the two histological types as designated in the proposed model for ovarian tumourigenesis in primary epithelial ovarian, fallopian tube or peritoneal cancer (EOC) patients.

Methods:

All consecutive EOC patients (n=632) after primary tumour debulking in our institution (09/2000–08/2010) were classified into one of two groups: type I tumours (n=100; 15.8%) composed of low-grade serous, low-grade endometrioid, clear cell, mucinous and transitional carcinomas; and Type II tumours (n=532; 84.1%) composed of high-grade serous, high-grade endometrioid, undifferentiated and malignant mixed-mesodermal tumours. Kaplan–Meier and logistic/Cox-regression analyses were performed to assess the impact of histological type on surgical outcome and survival.

Results:

Type II patients had a significantly higher incidence of advanced disease (FIGO III/IV) than Type I patients (79.8% vs 38%, respectively; P<0.001). Median CA125 values (438 vs 93 U ml⁻¹; P=0.001); operative time (258 vs 237 min; P=0.001); and incidence of incomplete tumour resection (34.4% vs 15% P<0.001) were significantly higher in patients with Type II. During a mean follow-up time of 23 months (range: 1–106), 17% of patients with type I vs 34.8% of patients with type II tumours relapsed and/or died (P<0.001). Overall survival (P=0.021) and progression-free survival (P=0.003) were also significantly higher in patients with type I tumours. Multivariate analysis, while identifying postoperative tumour residuals, positive lymph nodes and extrapelvic dissemination as independent predictors of survival, failed to demonstrate any prognostic significance of histological type.

Conclusion:

Type I EOC patients appear to present at earlier stages have significantly higher survival and more optimal surgical outcome compared with type II patients. However, in advanced stages, histology loses significance as an independent prognosticator.

SV40 T/t-common polypeptide inhibits angiogenesis and growth of HER2-overexpressing human ovarian cancer

Human epidermal growth factor receptor 2 (HER2) is frequently overexpressed in human ovarian cancers and its overexpression is associated with increased angiogenesis, increased metastasis and reduced survival. Inhibition of HER2 in HER2-overexpressing cancers can lead to reduced angiogenesis and improved survival. Previously, we reported that SV40 T/t-common polypeptide has transcriptional repression activity and can inhibit HER2 expression. In this study, we investigated the effect of T/t-common on the angiogenesis-inducing activity of HER2-overexpressing human SK-OV-3 ovarian cancer cells. We found that compared to conditioned medium from control SK-OV-3 cancer cells, conditioned medium from T/t-common-expressing SK-OV-3 cells had a reduced ability to induce endothelial cell migration and tube formation in vitro and microvessel formation in vivo. These data indicate that T/t-common can inhibit the ability of SK-OV-3 cancer cells to induce angiogenesis. T/t-common was found to be able to downregulate the expression of several proangiogenic factors, including vascular endothelial growth factor-A, interleukin-8, basic fibroblast growth factor, matrix metalloproteinase-2 and urokinase-type plasminogen activator, and upregulate antiangiogenic factors, including thrombospondin-1 and tissue inhibitor of metalloproteinases-1 in SK-OV-3 cancer cells. Finally, we demonstrated that T/t-common could inhibit the angiogenesis and growth of HER2-overexpressing human ovarian tumor in NOD/SCID mice. Taken together, the data suggest that T/t-common had the potential to be developed as a new antiangiogenic agent specific for treating HER2-overexpressing ovarian cancers.

Targeting angiogenesis in ovarian cancer

Results of standard chemotherapy in ovarian cancer are hampered by the development of drug resistance leading to disease recurrence. This prompted interest in the development of therapies targeting critical pathways responsible for tumor progression. Angiogenesis is a key process that enables ovarian cancer growth and metastasis in the peritoneal space. Its regulation relies on signaling mechanisms initiated by the vascular endothelial growth factor, the platelet-derived growth factor, the fibroblast growth factor, angiopoietins, and others. These pathways are not only important to the modulation of the tumor microenvironment and vasculature, but also control cancer cell proliferation and survival. In this review, we discuss preclinical evidence supporting the rationale for inhibiting these pathways and provide an overview for the clinical development of agents targeting them. Clinical trials evaluating such agents alone and in combination with chemotherapy are ongoing. Early clinical results position antiangiogenic therapy at the forefront of change to the standard treatment of difficult to treat ovarian cancer.

The adhesion molecule NCAM promotes ovarian cancer progression via FGFR signalling

Epithelial ovarian carcinoma (EOC) is an aggressive neoplasm, which mainly disseminates to organs of the peritoneal cavity, an event mediated by molecular mechanisms that remain elusive. Here, we investigated the expression and functional role of neural cell adhesion molecule (NCAM), a cell surface glycoprotein involved in brain development and plasticity, in EOC. NCAM is absent from normal ovarian epithelium but becomes highly expressed in a subset of human EOC, in which NCAM expression is associated with high tumour grade, suggesting a causal role in cancer aggressiveness. We demonstrate that NCAM stimulates EOC cell migration and invasion in vitro and promotes metastatic dissemination in mice. This pro-malignant function of NCAM is mediated by its interaction with fibroblast growth factor receptor (FGFR). Indeed, not only FGFR signalling is required for NCAM-induced EOC cell motility, but targeting the NCAM/FGFR interplay with a monoclonal antibody abolishes the metastatic dissemination of EOC in mice. Our results point to NCAM-mediated stimulation of FGFR as a novel mechanism underlying EOC malignancy and indicate that this interplay may represent a valuable therapeutic target.

Cordycepin blocks lung injury-associated inflammation and promotes BRCA1-deficient breast cancer cell killing by effectively inhibiting PARP

Cordycepin has been shown to interfere with a myriad of molecular processes from RNA elongation to kinase activity, and prevents numerous inflammatory processes in animal models. Here we show in a mouse model of LPS-induced acute lung injury that cordycepin prevents airway neutrophilia via a robust blockade of expression of several inflammatory genes, including the adhesion molecule ICAM-1 and VCAM-1, the cytokine/chemokine MCP-1, MIP-1α, MIP-2 and KC, and the chemokine receptor CXCR2. Such a blockade appears to be related to a severe reduction in TNF-α expression. Interestingly, in an in vitro system of A549 epithelial cell inflammation, cordycepin effectively blocked LPS-induced, but not TNF-α-induced, VCAM-1 expression. Such effects correlated with a marked reduction in p65-NF-κB activation as assessed by its phosphorylation at serine-536 but without an apparent effect on its nuclear translocation. The effects of cordycepin on the expression of VCAM-1 and ICAM-1, and of NF-κB activation and nuclear translocation upon TNF-α stimulation resembled the effects achieved upon poly(ADP-ribose) polymerase (PARP) inhibition, suggesting that cordycepin may function as a PARP inhibitor. Indeed, cordycepin blocked H(2)O(2)-induced PARP activation in A549 cells. In a cell-free system, cordycepin inhibited PARP-1 activity at nanomolar concentrations. Similar to PARP inhibitors, cordycepin significantly induced killing of breast cancer susceptibility gene (BRCA1)-deficient MCF-7 cells, supporting its therapeutic use for the treatment of BRCA-deficient breast cancers. With added antiinflammatory characteristics, therapies that include cordycepin may prevent potential inflammation triggered by traditional chemotherapeutic drugs. Cordycepin, to the best of our knowledge, represents the first natural product possessing PARP inhibitory traits.

Wine drinking and epithelial ovarian cancer risk: a meta-analysis

OBJECTIVE

Wine has been the focus in the prevention of epithelial ovarian cancer (EOC) development because resveratrol abundant in wine has anti-carcinogenic properties. However, epidemiologic results have been heterogenous in the chemopreventive effect of wine on the development of EOC. Thus, we performed a meta-analysis for comparing EOC risk between wine and never drinkers using previous related studies.

METHODS

After extensive search of the literature between January 1986 and December 2008, we analyzed 10 studies (3 cohort and 7 case control studies) with 135,871 women, who included 65,578 of wine and 70,293 of never drinkers.

RESULTS

In all studies, there was no significant difference in EOC risk between wine and never drinkers (odds ratio [OR], 1.13; 95% confidence interval [CI], 0.92 to 1.38; random effects). When we performed re-analysis according to the study design, 3 cohort and 7 case control studies showed that there were also no significant differences in EOC risk between wine and never drinkers, respectively (OR, 1.44 and 1.04; 95% CI, 0.74 and 2.82 and 0.88 to 1.22; random effects). In sub-analyses using 2 case-control studies, EOC risk was not different between former and never drinkers (OR, 1.12; 95% CI, 0.87 to 1.44; fixed effect), and between current and former drinkers (OR, 0.74; 95% CI, 0.41 to 1.34; random effects).

CONCLUSION

Although resveratrol, abundantly found in wine, is a promising naturally occurring compound with chemopreventive properties on EOC in preclinical studies, this meta-analysis suggests the epidemiologic evidence shows no association between wine drinking and EOC risk.

Activation of hedgehog signaling is not a frequent event in ovarian cancers

The hedgehog (Hh) signaling pathway regulates many processes of development and tissue homeostasis. Activation of hedgehog signaling has been reported in about 30% of human cancer including ovarian cancer. Inhibition of hedgehog signaling has been pursued as an effective strategy for cancer treatment including an ongoing phase II clinical trial in ovarian cancer. However, the rate of hedgehog signaling activation in ovarian cancer was reported differently by different groups. To predict the successful for future clinical trials of hedgehog signaling inhibitors in ovarian cancer, we assessed hedgehog pathway activation in 34 ovarian epithelial tumor specimens through analyses of target gene expression by in-situ hybridization, immunohistochemistry, RT-PCR and real-time PCR. In contrast to previous reports, we only detected a small proportion of ovarian cancers with hedgehog target gene expression, suggesting that identification of the tumors with activated hedgehog signaling activation will facilitate chemotherapy with hedgehog signaling inhibitors.