Oncogenic pathways implicated in ovarian epithelial cancer

Altered Organelle Calcium Transport in Ovarian Physiology and Cancer

Calcium levels have a huge impact on the physiology of the female reproductive system, in particular, of the ovaries. Cytosolic calcium levels are influenced by regulatory proteins (i.e., ion channels and pumps) localized in the plasmalemma and/or in the endomembranes of membrane-bound organelles. Imbalances between plasma membrane and organelle-based mechanisms for calcium regulation in different ovarian cell subtypes are contributing to ovarian pathologies, including ovarian cancer. In this review, we focused our attention on altered calcium transport and its role as a contributor to tumor progression in ovarian cancer. The most important proteins described as contributing to ovarian cancer progression are inositol trisphosphate receptors, ryanodine receptors, transient receptor potential channels, calcium ATPases, hormone receptors, G-protein-coupled receptors, and/or mitochondrial calcium uniporters. The involvement of mitochondrial and/or endoplasmic reticulum calcium imbalance in the development of resistance to chemotherapeutic drugs in ovarian cancer is also discussed, since Ca²⁺ channels and/or pumps are nowadays regarded as potential therapeutic targets and are even correlated with prognosis.

Inhibitory effects of delphinidin on the proliferation of ovarian cancer cells via PI3K/AKT and ERK 1/2 MAPK signal transduction

Delphinidin is a member of the anthocyanidin family and is a natural pigment in red cabbage, berries, sweet potatoes and grapes. It possesses nutraceutical properties against various chronic diseases and types of cancer. However, little is known about its preventative effects on epithelial ovarian cancer, a disease that is associated with a low survival rate, a poor prognosis and a high rate of recurrence. The results of the present study demonstrated that the proliferation of SKOV3 cells decreased in a dose-dependent manner in response to treatment with delphinidin, and the phosphorylation of carcinogenic protein kinases associated with the progression of epithelial ovarian cancer was affected by delphinidin treatment. The levels of phosphorylated protein kinase B (AKT), ribosomal protein S6 kinase β-1 (P70S6K), ribosomal protein S (S6), extracellular signal-regulated kinase (ERK)1/2 and p38 were suppressed by increasing concentrations of delphinidin. Furthermore, the combination of certain pharmacological inhibitors, including phosphoinositide 3-kinase (PI3K; LY294002), ERK1/2 (U0126) and delphinidin significantly reduced the proliferation of SKOV3 cells and the phosphorylation of each of those target proteins. In addition, delphinidin treatment exerted anti-proliferative effects on paclitaxel-resistant SKOV3 cells, compared with treatment with paclitaxel alone. These results indicate that delphinidin inhibits the proliferation of SKOV3 cells through inactivation of PI3K/AKT and ERK1/2 mitogen-activated protein kinase signaling cascades, and that this cell signaling pathway may be a pivotal therapeutic target for the prevention of epithelial ovarian cancer, including paclitaxel-resistant ovarian cancer.

Synuclein-γ (SNCG) expression in ovarian cancer is associated with high-risk clinicopathologic disease

Background

Synuclein gamma (SNCG) expression is associated with advanced disease and chemoresistance in multiple solid tumors. Our goal was to determine if SNCG protein expression in ovarian cancer was correlated with clinicopathologic variables and patient outcomes.

Methods

Tissue microarrays from primary tumors of 357 ovarian, fallopian tube, and primary peritoneal cancer patients, who underwent primary surgery at Roswell Park Cancer Institute between 1995 and 2007, were immunohistochemically stained for SNCG. A pathologist blinded to patient data scored tumors as positive if ≥10 % of the sample stained for SNCG. Medical records were reviewed for clinicopathologic and demographic variables. Between the positive and negative groups, Wilcoxon rank-sum test was used to compare the median ages and Fisher’s exact test was used to compare groups in categorical variables. Cox proportional hazard models examined associations between SNCG and overall and progression-free survival.

Results

The median follow-up was 36 months, median overall survival was 39 months, and median progression-free survival was 18 months. SNCG presence was associated with clinical variables of serous histology, grade 3 disease, suboptimal debulking, ascites at surgery, FIGO stage III-IV cancer, or initial CA-125 level >485. There was no significant difference in overall survival (HR 1.06 95 % CI 0.81–1.39 P 0.69) or progression-free survival (HR 1.16 95 % CI 0.89–1.50 P 0.28) for patients with or without SNCG expression.

Conclusions

SNCG expression in ovarian cancer is frequent in patients with high-risk features, but it does not correlate with chemotherapy response, overall survival, or progression-free survival.

Electronic supplementary material

The online version of this article (doi:10.1186/s13048-016-0281-4) contains supplementary material, which is available to authorized users.

Diagnosis value of serum soluble B7-H4 expression in non-small cell lung cancer

INTRODUCTION

B7-H4, a member of the inhibitory B7 family, can restrain T cell proliferation, activation, cytokine secretion, and may be involved in immune evasion in cancer patients.

OBJECTIVES

This aim of the study was to determine the expression level of soluble B7-H4 (sB7-H4) in circulation and to subsequently evaluate the clinical significance of circulating sB7-H4 in patients with non-small cell lung cancer (NSCLC).

METHODS

Serum specimens from 128 patients with NSCLC, 100 healthy volunteers (HV), and 80 patients with benign lung diseases (BLD) were collected. The concentrations of sB7-H4 were measured by sandwich enzyme-linked immunosorbent assay.

RESULTS

Serum sB7-H4 levels in patients with NSCLC were significantly higher than those in patients with BLD (P < 0.05), or those in HV (P < 0.05). Using a cutoff of 27.8 ng/mL, the sensitivity and specificity of sB7-H4 in differentiating between patients with NSCLC and patients with BLD, and between patients with NSCLC and HV was, 46.9% and 92.5%, and 54.7% and 95.0%, respectively. An area under the curve (AUC) for NSCLC resulting from sB7-H4 (0.863), which was significantly better than any other tumour markers tested including CA125 (0.763), and CEA (0.775).

CONCLUSION

In conclusion, assessment of serum sB7-H4 levels could be considered as a diagnostic biomarker for NSCLC.

Serum B7-H4 expression is a significant prognostic indicator for patients with gastric cancer

Background

B7-H4 is a novel B7 ligand that plays an important role in the T cell-mediated immune response as a negative regulator. Previous studies have suggested the aberrant expression of membrane B7-H4 in tumor cells. The aim of this study is to determine the expression levels of preoperative soluble B7-H4 (sB7-H4) in circulation and to investigate the correlations between sB7-H4 levels and clinicopathological parameters as well as the survival rate of patients with gastric cancer.

Methods

Blood specimens from 132 patients with gastric cancer and 63 healthy volunteers were analyzed by sandwich enzyme-linked immunosorbent assay.

Results

Median concentrations of sB7-H4 in patients with gastric cancer were significantly higher than those in healthy volunteers (16.85 versus 10.46 ng/mL; P = 0.008). Median levels of sB7-H4 were significantly correlated with tumor size, lymph node metastasis, the depth of tumor invasion and tumor-node-metastasis classification (P = 0.002, P = 0.001, P = 0.041 and P <0.001, respectively), but not with sex, age, tumor location or histological subtype (all P >0.05). Additionally, the overall survival rate was significantly lower in patients with high sB7-H4 levels when compared with low sB7-H4 levels (50.0% versus 77.3%, χ² = 10.78, P = 0.001). Moreover, multivariate analysis demonstrated that the risk of death was significantly higher in patients with high sB7-H4 levels than in those with low sB7-H4 levels (P = 0.039).

Conclusions

sB7-H4 is a valuable blood marker for predicting the progression and prognosis of patients with gastric cancer.

Development of inhibitors of heterotrimeric Gαi subunits

Heterotrimeric G-proteins are the immediate downstream effectors of G-protein coupled receptors (GPCRs). Endogenous protein guanine nucleotide dissociation inhibitors (GDIs) like AGS3/4 and RGS12/14 function through GPR/Goloco GDI domains. Extensive characterization of GPR domain peptides indicate they function as selective GDIs for Gαi by competing for the GPCR and Gβγ and preventing GDP release. We modified a GPR consensus peptide by testing FGF and TAT leader sequences to make the peptide cell permeable. FGF modification inhibited GDI activity while TAT preserved GDI activity. TAT-GPR suppresses G-protein coupling to the receptor and completely blocked α2-adrenoceptor (α2AR) mediated decreases in cAMP in HEK293 cells at 100nM. We then sought to discover selective small molecule inhibitors for Gαi. Molecular docking was used to identify potential molecules that bind to and stabilize the Gαi-GDP complex by directly interacting with both Gαi and GDP. Gαi-GTP and Gαq-GDP were used as a computational counter screen and Gαq-GDP was used as a biological counter screen. Thirty-seven molecules were tested using nucleotide exchange. STD NMR assays with compound 0990, a quinazoline derivative, showed direct interaction with Gαi. Several compounds showed Gαi specific inhibition and were able to block α2AR mediated regulation of cAMP. In addition to being a pharmacologic tool, GDI inhibition of Gα subunits has the advantage of circumventing the upstream component of GPCR-related signaling in cases of overstimulation by agonists, mutations, polymorphisms, and expression-related defects often seen in disease.

p27KIP1 is involved in ERK1/2-mediated MMP-9 expression via the activation of NF-κB binding in the IL-7-induced migration and invasion of 5637 cells

Interleukin-7 (IL-7) plays a pivotal role in the development and survival of lymphocytes, but its role in cancer cell responses remains unexplained. In this study, IL-7 treatment resulted in a significant induction in the wound-healing migration and Matrigel invasion of the 5637 bladder cancer cells, but it did not result in cell proliferation. In addition, IL-7 treatment strongly induced MMP-9 expression, and increased the binding activation of NF-κB and AP-1 motifs, the important transcription factors that regulate MMP-9 expression. Moreover, the treatment of 5637 cells with IL-7 stimulated the phosphorylation of ERK1/2. U0126, an ERK1/2-specific inhibitor, blocked IL-7-induced cell migration and invasion, and also suppressed the expression of MMP-9 in the presence of IL-7. Inhibition of the ERK1/2 function consistently reversed the binding activity of NF-κB without altering AP-1 activation in IL-7-stimulated cells. Among the cell cycle regulators examined, only the expression of the cell cycle inhibitor p27KIP1 was induced by IL-7. Moreover, the inhibition of p27KIP1 by small interfering RNA (siRNA) abolished the migration, invasion and phosphorylation of ERK1/2, the expression of MMP-9, and the binding activity of the NF-κB motif in IL-7-stimulated 5637 cells. These results demonstrated that the cell cycle inhibitor p27KIP1 is involved in ERK1/2-mediated MMP-9 expression via activation of the NF-κB binding motif, which leads to the migration and invasion of bladder cancer cells induced by IL-7. These novel results could help explain the migration and invasion of bladder tumor cells.

Suppression of GNAI2 message in ovarian cancer

Background

Understanding the integration of hormone signaling and how it impacts oncogenesis is critical for improved cancer treatments. Here we elucidate GNAI2 message alterations in ovarian cancer (OvCa). GNAI2 is a heterotrimeric G protein which couples cell surface hormone receptors to intracellular enzymes, and is best characterized for its direct role in regulating cAMP response element-binding protein (CREB) function by decreasing intracellular cAMP through inhibiting adenylyl cyclase.

Methods

We probed the Origene human OvCa array for the presence of polymorphisms and gene expression alterations of GNAI2 using directing sequencing and qPCR. These data were supported by database mining of the [NCBI NIH GSE:6008, GSE:14764, GSE:29450, GDS:4066, GDS:3297, GSE:32474, and GSE:2003] datasets.

Results

No significant polymorphisms were found, including an absence of the gip2 oncogene. However, 85.9% of (506 of 589) OvCa patients had decreased GNAI2 message. Further characterization demonstrated that the GNAI2 message was on average decreased 54% and maximally decreased by 2.8 fold in clear cell carcinoma. GNAI2 message decreased in early stage cancer while message was increased compared to normal in advanced cancers. The changes in GNAI2 also correlated to deregulation of CREB, Fos, Myc, cyclins, Arf, the transition from estrogen dependence to independence, and metastatic potential.

Conclusion

These data strongly implicate GNAI2 as a critical regulator of oncogenesis and an upstream driver of cancer progression in OvCa.

B7-H4 enhances oncogenicity and inhibits apoptosis in pancreatic cancer cells

B7-H4 is expressed in a variety of tumor cells and functions as a negative regulator of T cells. However, clarification is needed as to whether B7-H4 mediates tumorigenesis through mechanisms, such as apoptosis, in addition to mediating tumor immune escape. We investigate the mechanisms involved in enhanced oncogenicity and the inhibition of apoptosis by B7-H4 in pancreatic cancer cells. Short interfering RNAs (siRNAs) specific for B7-H4 were evaluated for their ability to knockdown B7-H4 mRNA and protein expression in pancreatic cancer cells and the most effective siRNA was selected for investigating the effect of B7-H4 gene silencing in a number of functional assays. The inhibition of B7-H4 increased cell-cell adhesion and decreased the formation of pseudopodia. It also increased the expression of E-cadherin and decreased the expression of vimentin and CD44. B7-H4 siRNA inhibited cell proliferation, colony formation and migration of pancreatic cancer cells. Moreover, increased apoptosis in pancreatic cancer cells following B7-H4 silencing was demonstrated in vitro by using flow cytometry and in a xenograft tumor model and was associated with increased caspase activity and decreased Erk1/2 phosphorylation both in vitro and in vivo. Loss of B7-H4 function thus prevents tumor growth through many processes, including the induction of apoptosis and inhibition of the Erk1/2 signaling pathway indicating that B7-H4 is a cancer promoter and a potentially important therapeutic target. B7-H4 inhibition might offer an exciting opportunity to inhibit the progression of human pancreatic cancers.

Fibroblast growth factor 2 induces E-cadherin down-regulation via PI3K/Akt/mTOR and MAPK/ERK signaling in ovarian cancer cells

Fibroblast growth factor 2 (FGF2) is produced by ovarian cancer cells and it has been suggested to play an important role in tumor progression. In this study, we report that FGF2 treatment down-regulated E-cadherin by up-regulating its transcriptional repressors, Slug and ZEB1, in human ovarian cancer cells. The pharmacological inhibition of phosphatidylinositol-3-kinase (PI3K), mammalian target of rapamycin (mTOR), and MEK suggests that both PI3K/Akt/mTOR and MAPK/ERK signaling are required for FGF2-induced E-cadherin down-regulation. Moreover, FGF2 up-regulated Slug and ZEB1 expression via the PI3K/Akt/mTOR and MAPK/ERK signaling pathways, respectively. Finally, FGF2-induced cell invasion was abolished by the inhibition of the PI3K/Akt/mTOR and MAPK/ERK pathways, and the forced expression of E-cadherin diminished the intrinsic invasiveness of ovarian cancer cells as well as the FGF2-induced cell invasion. This study demonstrates a novel mechanism in which FGF2 down-regulates E-cadherin expression through the activation of PI3K/Akt/mTOR and MAPK/ERK signaling, and the up-regulation of Slug and ZEB1 in human ovarian cancer cells.

The RUNX1 transcription factor is expressed in serous epithelial ovarian carcinoma and contributes to cell proliferation, migration and invasion

Previously, we have identified the RUNX1 gene as hypomethylated and overexpressed in post-chemotherapy (CT) primary cultures derived from epithelial ovarian cancer (EOC) patients, when compared with primary cultures derived from matched primary (prior to CT) tumors. Here we show that RUNX1 displays a trend of hypomethylation, although not significant, in omental metastases compared with primary EOC tumors. Surprisingly, RUNX1 displayed significantly higher expression not only in metastatic tissue, but also in high-grade primary tumors and even in low malignant potential tumors. The RUNX1 expression levels were almost identical in primary tumors and omental metastases, suggesting that RUNX1 hypomethylation might have a limited impact on its overexpression in advanced (metastatic) stage of the disease. Knockdown of the RUNX1 expression in EOC cells led to sharp decrease of cell proliferation and induced G 1 cell cycle arrest. Moreover, RUNX1 suppression significantly inhibited EOC cell migration and invasion. Gene expression profiling and consecutive network and pathway analyses confirmed these findings, as numerous genes and pathways known previously to be implicated in ovarian tumorigenesis, including EOC tumor invasion and metastasis, were found to be downregulated upon RUNX1 suppression, while a number of pro-apoptotic genes and some EOC tumor suppressor genes were induced. Taken together, our data are indicative for a strong oncogenic potential of the RUNX1 gene in EOC progression and suggest that RUNX1 might be a novel EOC therapeutic target. Further studies are needed to more completely elucidate the functional implications of RUNX1 and other members of the RUNX gene family in ovarian tumorigenesis.

An RNA interference lethality screen of the human druggable genome to identify molecular vulnerabilities in epithelial ovarian cancer

Targeted therapies have been used to combat many tumor types; however, few have effectively improved the overall survival in women with epithelial ovarian cancer, begging for a better understanding of this deadly disease and identification of essential drivers of tumorigenesis that can be targeted effectively. Therefore, we used a loss-of-function screening approach to help identify molecular vulnerabilities that may represent key points of therapeutic intervention. We employed an unbiased high-throughput lethality screen using a 24,088 siRNA library targeting over 6,000 druggable genes and studied their effects on growth and/or survival of epithelial ovarian cancer (EOC) cell lines. The top 300 “hits” affecting the viability of A1847 cells were rescreened across additional EOC cell lines and non-tumorigenic, human immortalized ovarian epithelial cell lines. Fifty-three gene candidates were found to exhibit effects in all tumorigenic cell lines tested. Extensive validation of these hits refined the list to four high quality candidates (HSPA5, NDC80, NUF2, and PTN). Mechanistic studies show that silencing of three genes leads to increased apoptosis, while HSPA5 silencing appears to alter cell growth through G1 cell cycle arrest. Furthermore, two independent gene expression studies show that NDC80, NUF2 and PTN were significantly aberrantly overexpressed in serous adenocarcinomas. Overall, our functional genomics results integrated with the genomics data provide an important unbiased avenue towards the identification of prospective therapeutic targets for drug discovery, which is an urgent and unmet clinical need for ovarian cancer.

Quantitative immunoproteomics analysis reveals novel MHC class I presented peptides in cisplatin-resistant ovarian cancer cells

Platinum-based chemotherapy is widely used to treat various cancers including ovarian cancer. However, the mortality rate for patients with ovarian cancer is extremely high, largely due to chemo-resistant progression in patients who respond initially to platinum based chemotherapy. Immunotherapy strategies, including antigen specific vaccines, are being tested to treat drug resistant ovarian cancer with variable results. The identification of drug resistant specific tumor antigens would potentially provide significant improvement in effectiveness when combined with current and emerging therapies. In this study, using an immunoproteomics method based on iTRAQ technology and an LC-MS platform, we identified 952 MHC class I presented peptides. Quantitative analysis of the iTRAQ labeled MHC peptides revealed that cisplatin-resistant ovarian cancer cells display increased levels of MHC peptides derived from proteins that are implicated in many important cancer pathways. In addition, selected differentially presented epitope specific CTL recognize cisplatin-resistant ovarian cancer cells significantly better than the sensitive cells. These over-presented, drug resistance specific MHC class I associated peptide antigens could be potential targets for the development of immunotherapeutic strategies for the treatment of ovarian cancer including the drug resistant phenotype.

Integrin β1 mediates epithelial growth factor-induced invasion in human ovarian cancer cells

Integrins function as cell-extracellular matrix adhesion proteins and have been implicated in tumor progression. In ovarian tumors, elevated integrin β1 expression correlates with high clinical stage and poor patient survival. In this study, we report that EGF treatment up-regulated integrin β1 mRNA and protein levels in ovarian cancer cells. Moreover, pharmacological inhibition of MEK totally abolished EGF-induced integrin β1 up-regulation and cell invasion suggesting that MAPK/ERK signaling is required for EGF-induced integrin β1 up-regulation and cell invasion. Furthermore, we found that knockdown of integrin β1 expression reduced the intrinsic invasiveness of ovarian cancer cells and the EGF-induced cell invasion. Finally, we found that overexpression of integrin β1 was sufficient to promote ovarian cancer cell invasion. This study demonstrates that integrin β1 mediates EGF-induced cell invasion in ovarian cancer.

Proteomic analysis reflects different histologic subtypes of epithelial ovarian cancer

Ovarian carcinoma is a significant cause of cancer mortality in women worldwide. As a heterogeneous disease, distinct clinical and molecular characteristics exist among different histologic subtypes. With the developments in proteomics, surfaced-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) is sensitive enough to detect minute quantity of proteins from serum or microdissected cryostat sections. Herein we hypothesized that differentially expressed protein profiles exist in ovarian carcinomas with distinct histologic subtypes. Compared with endometrioid carcinoma, two peaks were significantly higher in serous carcinoma with the m/z of 3622 Da and 4778 Da, reinforcing the need to treat different histologic subtypes of ovarian cancer as different disease entities. Better understanding of these potential diagnostic and therapeutic biomarkers followed with proof-of-target effect will finally contribute to rational combinations of novel therapy and improve individual ovarian cancer patient outcome.

Effects of metastasis-associated in colon cancer 1 inhibition by small hairpin RNA on ovarian carcinoma OVCAR-3 cells

Background

Metastasis-associated in colon cancer 1 (MACC1) is demonstrated to be up-regulated in several types of cancer, and can serve as biomarker for cancer invasion and metastasis. To investigate the relations between MACC1 and biological processes of ovarian cancer, MACC1 specific small hairpin RNA (shRNA) expression plasmids were used to investigate the effects of MACC1 inhibition on ovarian carcinoma OVCAR-3 cells.

Methods

Expressions of MACC1 were detected in different ovarian tissues by immunohistochemistry. MACC1 specific shRNA expression plasmids were constructed and transfected into OVCAR-3 cells. Then, expressions of MACC1 were examined by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Cell proliferation was observed by MTT and monoplast colony formation assay. Flow cytometry and TUNEL assay were used to measure cell apoptosis. Cell migration was assessed by wound healing and transwell migration assay. Matrigel invasion and xenograft model assay were performed to analyze the potential of cell invasion. Activities of Met, MEK1/2, ERK1/2, Akt, cyclinD1, caspase3 and MMP2 protein were measured by Western blot.

Results

Overexpressions of MACC1 were detected in ovarian cancer tissues. Expression of MACC1 in OVCAR-3 cells was significantly down-regulated by MACC1 specific small hairpin RNA. In OVCAR-3 cells, down-regulation of MACC1 resulted in significant inhibition of cell proliferation, migration and invasion, meanwhile obvious enhancement of apoptosis. As a consequence of MACC1 knockdown, expressions of Met, p-MEK1/2, p-ERK1/2, cyclinD1 and MMP2 protein decreased, level of cleaved capase3 was increased.

Conclusions

RNA interference (RNAi) against MACC1 could serve as a promising intervention strategy for gene therapy of ovarian carcinoma, and the antitumor effects of MACC1 knockdown might involve in the inhibition of HGF/Met and MEK/ERK pathways.

Frequent genetic abnormalities of the PI3K/AKT pathway in primary ovarian cancer predict patient outcome

Identification and characterization of underlying genetic aberrations could facilitate diagnosis and treatment of ovarian cancer. Copy number analysis using array Comparative Genomic Hybridization (aCGH) on 93 primary ovarian tumors identified PI3K/AKT pathway as the most frequently altered cancer related pathway. Furthermore, survival analyses to correlate gene copy number and mutation data with patient outcome showed that copy number gains of PIK3CA, PIK3CB, and PIK3R4 in these tumors were associated with decreased survival. To confirm these findings at the protein level, immunohistochemistry (IHC) for PIK3CA product p110α and p-Akt was performed on tissue microarrays from 522 independent serous ovarian cancers. Overexpression of either of these two proteins was found to be associated with decreased survival. Multivariant analysis from these samples further showed that overexpression of p-AKT and/or p110α is an independent prognostic factor for these tumors. siRNAs targeting altered PI3K/AKT pathway genes inhibited proliferation and induced apoptosis in ovarian cancer cell lines. In addition, the effect of the siRNAs in different cell lines seemed to correlate with the particular genetic alterations that the cell line carries. These results strongly support the utilization of PI3K pathway inhibitors in ovarian cancer. They also suggest identifying the specific component in the PI3K pathway that is genetically altered has the potential to help select the most effective therapy. Both mutation as well as copy number changes can be used as predictive markers for this purpose.

Frequent genetic abnormalities of the PI3K/AKT pathway in primary ovarian cancer predict patient outcome

Identification and characterization of underlying genetic aberrations could facilitate diagnosis and treatment of ovarian cancer. Copy number analysis using array Comparative Genomic Hybridization (aCGH) on 93 primary ovarian tumors identified PI3K/AKT pathway as the most frequently altered cancer related pathway. Furthermore, survival analyses to correlate gene copy number and mutation data with patient outcome showed that copy number gains of PIK3CA, PIK3CB, and PIK3R4 in these tumors were associated with decreased survival. To confirm these findings at the protein level, immunohistochemistry (IHC) for PIK3CA product p110α and p-Akt was performed on tissue microarrays from 522 independent serous ovarian cancers. Overexpression of either of these two proteins was found to be associated with decreased survival. Multivariant analysis from these samples further showed that overexpression of p-AKT and/or p110α is an independent prognostic factor for these tumors. siRNAs targeting altered PI3K/AKT pathway genes inhibited proliferation and induced apoptosis in ovarian cancer cell lines. In addition, the effect of the siRNAs in different cell lines seemed to correlate with the particular genetic alterations that the cell line carries. These results strongly support the utilization of PI3K pathway inhibitors in ovarian cancer. They also suggest identifying the specific component in the PI3K pathway that is genetically altered has the potential to help select the most effective therapy. Both mutation as well as copy number changes can be used as predictive markers for this purpose.

Activation of the MEK-S6 pathway in high-grade ovarian cancers

The primary objective of this study is to show the activation and analyze the regulation of the MEK- S6 kinase pathway in high-grade ovarian cancer. Phospho-ERK (pERK), a direct substrate of MEK and 2 phosphorylation sites on the ribosomal protein, S6, Ser235/236, and Ser240/244, which are both targeted by the MEK and PI3-kinase/AKT pathways, were analyzed in 13 cell lines, 28 primary cancers and 8 cases of cancer cells from ascites. In primary cancers, ERK and S6 phosphorylation was measured by immunohistochemistry (IHC). pERK, pS6, pAKT, and p4EBP1 were also measured by Western blotting (WB). The regulation of S6 phosphorylation by the MEK and PI3-kinase pathways was determined in ovarian cancer cell lines. We observed frequent pERK expression in primary ovarian cancers (100% by WB, 75% by IHC) but not in ovarian cancer cells from ascites (25% of cases by WB). The activation of the AKT pathway, measured by pAKT expression occurred in 7 cases of primary ovarian cancer by WB, but in none of the ascites samples. In ovarian cancer cell lines, the MEK pathway had a greater effect on S6 phosphorylation in cells without hyperactive AKT signaling. Our data suggest that MEK is a potential drug target in high-grade ovarian cancer, however, cancer cells with hyperactive AKT and cancer cells in ascites may be less responsive to MEK inhibition. The phosphorylation of S6 as a specific biomarker for either MEK or PI3-kinase pathway activation should be used with caution.

Strong cytotoxic effect of the bradykinin antagonist BKM-570 in ovarian cancer cells--analysis of the molecular mechanisms of its antiproliferative action

The standard chemotherapy for epithelial ovarian cancer (EOC) patients is currently a combination of taxane and platinum. However, most EOC patients still suffer relapses, and there is an immediate need for the development of novel and more effective therapeutic modalities against this deadly disease. Recently, the nonpeptide bradykinin (BK) antagonist 2,3,4,5,6-pentafluorocinnamoyl-(o-2,6-dichlorobenzyl)-l-tyrosine-N-(4-amino-2,2,6,6-tetramethyl-piperidyl) amide (BKM-570) was shown to cause impressive growth inhibition of lung and prostate tumors, displaying superior in vivo inhibitory effects than convential chemotherapeutic drugs. Here, we investigated BKM-570 cytotoxic effects in two EOC cell lines, derived from different EOC histopathologies: a clear cell carcinoma (TOV-21), and an endometrioid carcinoma (TOV-112). We showed that BKM-570 effectively inhibited the growth of ovarian cancer cells, as its cytotoxic effects were comparable to those of cisplatin, and were independent of the functional status of BK receptors. Moreover, BKM-570 synergized with cisplatin in inhibiting EOC cell growth. To better understand the molecular mechanisms of the antiproliferative action of this BK antagonist in EOC cells, we performed gene expression profiling in TOV-21 and TOV-112 cells following treatment with 10 μM BKM-570 for 24 h. BKM-570 displayed similar cytotoxic effects in the two cell lines analyzed, as genes with previously shown involvement in apoptosis/antiapoptosis and cell adhesion were proportionally upregulated and downregulated in both cell lines, whereas genes involved in basic cellular mechanisms, including cell growth and maintenance, metabolism, cell cycle control, inflammatory and immune response, signal transduction, protein biosynthesis, transcription regulation, and transport, were predominantly downregulated upon treatment. Our data are indicative of the therapeutic potential of BKM-570 and related compounds in EOC management.

Tumor expression of B7-H4 predicts poor survival of patients suffering from gastric cancer

To establish the prognostic value of B7-H4 expression by tumor cells in gastric cancer patients, we evaluated the association of B7-H4 expression with clinicopathologic factors and overall survival of gastric cancer patients. A retrospective cohort study including 156 gastric cancer patients was performed in the present report. Immunohistochemical assay was used to evaluate the expression of B7-H4 in the surgical specimens of gastric cancer tissues. Multi-univariate COX model was then used to evaluate the association of B7-H4 expression with the patients' survival and clinicopathological parameters. B7-H4 expression in the gastric cancer cells was observed in about 44.9% gastric cancer specimens. Univariate analysis demonstrated that there was no correlation between B7-H4 expression and sex, age, histological type, pathological grade or tumor size. In contrast, B7-H4 expression correlated positively with cancer invasiveness and lymph node metastasis. In addition, the median overall survival time of patients with lower B7-H4 expression was 13 months longer than that of patients with higher expression (chi(2) = 12.38, P < 0.0001), and the median disease-free survival time of patients with lower B7-H4 expression was significantly longer than that of patients with higher expression (33 vs. 16 months, chi(2) = 14.977, P < 0.0001). After adjustment for other confounding factors, the COX model analysis indicated that the death risk was significantly higher in patients with higher B7-H4 expression than those with lower expression (RR = 1.85, 95% CI = 1.15-2.96). The present study demonstrated that higher B7-H4 expression in cancer cells was associated with poor prognosis of gastric cancer patients. This is consistent with the idea that B7-H4 promotes cancer progression, likely via inhibition of anti-tumor immune responses.

Atypical protein kinase C zeta exhibits a proapoptotic function in ovarian cancer

Intracellular signaling governed by serine/threonine kinases comprises the molecular interface between cell surface receptors and the nuclear transcriptional machinery. The protein kinase C (PKC) family members are involved in the control of many signaling processes directing cell proliferation, motility, and survival. Here, we examined a role of different PKC isoenzymes in protein phosphatase 2A (PP2A) and HRSL3 tumor suppressor-dependent cell death induction in the ovarian carcinoma cell line OVCAR-3. Phosphorylation and activity of PKC isoenzymes were measured in response to PP2A or phosphoinositide 3-kinase inhibition or HRSL3 overexpression. These experiments indicated a regulation of PKC, epsilon, zeta, and iota through PP2A and/or HRSL3, but not of PKCalpha and beta. Using isoform-specific peptide inhibitors and overexpression approaches, we verified a contribution to PP2A- and HRLS3-dependent apoptosis only for PKCzeta, suggesting a proapoptotic function of this kinase. We observed a significant proportion of human ovarian carcinomas expressing high levels of PKCzeta, which correlated with poor prognosis. Primary ovarian carcinoma cells isolated from patients also responded to okadaic acid treatment with increased phosphorylation of PKCzeta and apoptosis induction. Thus, our data indicate a contribution of PKCzeta in survival control in ovarian carcinoma cells and suggest that upregulation or activation of tyrosine kinase receptors in this tumor might impinge onto apoptosis control through the negative regulation of the atypical PKCzeta.

Integrated proteomic analysis of human cancer cells and plasma from tumor bearing mice for ovarian cancer biomarker discovery

Background

The complexity of the human plasma proteome represents a substantial challenge for biomarker discovery. Proteomic analysis of genetically engineered mouse models of cancer and isolated cancer cells and cell lines provide alternative methods for identification of potential cancer markers that would be detectable in human blood using sensitive assays. The goal of this work is to evaluate the utility of an integrative strategy using these two approaches for biomarker discovery.

Methodology/Principal Findings

We investigated a strategy that combined quantitative plasma proteomics of an ovarian cancer mouse model with analysis of proteins secreted or shed by human ovarian cancer cells. Of 106 plasma proteins identified with increased levels in tumor bearing mice, 58 were also secreted or shed from ovarian cancer cells. The remainder consisted primarily of host-response proteins. Of 25 proteins identified in the study that were assayed, 8 mostly secreted proteins common to mouse plasma and human cancer cells were significantly upregulated in a set of plasmas from ovarian cancer patients. Five of the eight proteins were confirmed to be upregulated in a second independent set of ovarian cancer plasmas, including in early stage disease.

Conclusions/Significance

Integrated proteomic analysis of cancer mouse models and human cancer cell populations provides an effective approach to identify potential circulating protein biomarkers.

Comparative proteomic study of two closely related ovarian endometrioid adenocarcinoma cell lines using cIEF fractionation and pathway analysis

The proteomic profiles from two distinct ovarian endometrioid tumor-derived cell lines, (MDAH-2774 and TOV-112D) each with different morphological characteristics and genetic mutations, have been studied. Characterization of the differential global protein expression between these two cell lines has important implications for the understanding of the pathogenesis of ovarian endometrioid carcinoma. In this comparative proteomic study, extensive fractionation of peptides generated from whole-cell trypsin digestion was achieved by coupling cIEF in the first-dimensional separation with capillary LC (RP-HPLC) in the second dimensional separation. Online analysis was performed using tandem mass spectra acquired by a linear ion trap mass spectrometer from triplicate runs. A total of 1749 and 1955 proteins with protein probability above 0.95 were identified from MDAH-2774 and TOV-112D after filtering through Peptide Prophet/Protein Prophet software. Differentially expressed proteins were further investigated by ingenuity pathway analysis (IPA) to reveal the association with important biological functions. Canonical pathway analysis using IPA demonstrates that important signaling pathways are highly associated with one of these two cell lines versus the other, such as the PI3K/AKT pathway, which is found to be significantly predominant in MDAH-2774 but not in TOV-112D. Also, protein network analysis using IPA highlights p53 as a central hub relating to other proteins from the connectivity map. These results illustrate the utility of high throughput proteomics methods using large-scale proteome profiling combined with bioinformatics tools to identify differential signaling pathways, thus contributing to the understanding of mechanisms of deregulation in neoplastic cells.

Transient receptor potential channel C3 contributes to the progression of human ovarian cancer

Ovarian cancer (OC) is the leading cause of death from gynecological malignancy. However, the mechanism by which OC develops remains largely unknown. Increases in cytosolic free Ca(2+) ([Ca(2+)](i)) can result in different physiological changes including cell growth, differentiation and death. The transient receptor potential (TRP) C channels are nonselective cation channels with permeability to Ca(2+). Here we report that TRPC3 channels promote human OC growth. The TRPC3 protein levels in human OC specimens were greatly increased than those in normal ovarian specimens. Downregulating TRPC3 expression in SKOV3 cells, a human OC cell line, led to reduction of proliferation, suppression in epidermal growth factor-induced Ca(2+) influx, dephosphorylation of Cdc2 and CaMKIIalpha and prolonged progression through M phase of these cells. Further, decreased the expression of TRPC3 suppressed the tumor formation generated by injecting SKOV3 cells in nude mice. Together, our results suggest that increased activity of TRPC3 channels is necessary for the development of OCs.

Matrix metalloproteinase 9 is a mediator of epidermal growth factor-dependent e-cadherin loss in ovarian carcinoma cells

Epidermal growth factor (EGF) receptor (EGFR) is frequently elevated in epithelial ovarian cancer, and E-cadherin expression is often reduced in advanced disease. In this study, we investigated a mechanism by which EGFR activation promotes disruption of adherens junctions through induction of matrix metalloproteinase 9 (MMP-9). We show that EGFR activation down-modulates E-cadherin, and broad spectrum MMP inhibition ameliorates EGF-stimulated junctional disruption and loss of E-cadherin protein. MMP-9 involvement in EGF-dependent down-regulation of E-cadherin was determined by siRNA specifically directed against MMP-9. Furthermore, treatment with recombinant MMP-9 or transient expression of MMP-9 is sufficient to reduce E-cadherin levels in differentiated ovarian tumor cells. Stable overexpression of MMP-9 led to a loss of E-cadherin and junctional integrity, and promoted a migratory and invasive phenotype. Thus, elevated MMP-9 protein expression is sufficient for junctional disruption and loss of E-cadherin in these cells. The associations between EGFR activation, MMP-9 expression, and E-cadherin were investigated in human ovarian tumors and paired peritoneal metastases wherein immunohistochemical staining for activated (phospho) EGFR and MMP-9 colocalized with regions of reduced E-cadherin. These data suggest that regulation of MMP-9 by EGFR may represent a novel mechanism for down-modulation of E-cadherin in ovarian cancer.

Reversal of the malignant phenotype of ovarian cancer A2780 cells through transfection with wild-type PTEN gene

OBJECTIVE

PTEN (phosphatase and tensin homologue deleted on chromosome 10) is a tumor suppressor gene identified on human chromosome 10q23. Substantial studies have demonstrated that PTEN can inhibit cell proliferation, migration and invasion of many cancer cells. The purpose of this study was to determine whether upregulation of PTEN gene by transfection wild-type PTEN gene to ovarian cancer cells can inhibit growth and migration and to explore the potential for PTEN gene therapy of ovarian cancers.

METHOD

Wild-type and phosphatase-inactive (C124A) PTEN plasmids were transfected into ovarian epithelial cancer A2780 cells, and their effects on cell apoptosis, cell proliferation, cell migration and cell invasion were analyzed by flow cytometry analysis, TUNEL assay, MTT assay, wound-healing assay and transwell assay.

RESULTS

Both wild-type and mutant PTEN can upregulate the expression of PTEN gene dramatically; however, it is wild-type PTEN not phosphatase-inactive PTEN that can induce apoptosis and decrease cell migration, invasion and proliferation in ovarian cancer cells.

CONCLUSION

These results demonstrated that PTEN had played an important role in the cell proliferation, cell migration and invasion dependent on its phosphatase activity. Enhanced expression of PTEN by gene transfer is sufficient to reverse the malignant phenotype of ovarian cancer cells and transfection of ovarian cancer cells with wild-type PTEN gene might be another novel approach for therapeutic intervention in ovarian cancer.

Activation of KLF8 transcription by focal adhesion kinase in human ovarian epithelial and cancer cells

KLF8 (Krüppel-like factor 8) is a transcription factor downstream of focal adhesion kinase (FAK) important in the regulation of the cell cycle and also plays a critical role in oncogenic transformation and epithelial to mesenchymal transition. Here we report the mechanisms by which FAK regulates KLF8 expression in human ovarian epithelial and cancer cells. We show that the overexpression of both KLF8 and FAK in the human ovarian cancer cells as compared with the normal human ovarian surface epithelial cells is critical for cell growth. Using promoter luciferase reporter assays, we demonstrate that exogenous FAK strongly promotes the activity of the KLF8 promoter, and knockdown of FAK inhibits it. KLF8 promoter activity and mRNA levels are induced by expression of constitutively active (CA) phosphatidylinositol 3-kinase (PI3K) or CA-Akt but are repressed by dominant negative Akt or the PI3K inhibitor LY294002. Disruption of an Sp1 binding site in the KLF8 promoter abolishes the FAK- or Sp1-mediated promoter activation. Sp1 knockdown prevents the KLF8 promoter from being activated by Sp1 or CA-Akt, and expression of CA-Akt enhances Sp1 expression in SKOV3ip1 cells. Chromatin immunoprecipitation and oligonucleotide precipitation results show that Sp1 binds to the KLF8 promoter. Taken together, our data suggest that FAK induces KLF8 expression in human ovarian cancer cells by activating the PI3K-Akt signaling pathway, leading to the activation of KLF8 promoter by Sp1.

Alteration of cell-cycle regulation in epithelial ovarian cancer

In spite of the clinical importance of epithelial ovarian cancer (EOC), little is known about the pathobiology of its precursor lesions and progression. Regulatory mechanisms of the cell cycle are mainly composed of cyclins, cyclin-dependent kinases (CDK), and CDK inhibitors. Alteration of these mechanisms results in uncontrolled cell proliferation, which is a distinctive feature of human cancers. This review describes the current state of knowledge about the alterations of cell-cycle regulations in the context of p16-cyclin D1-CDK4/6-pRb pathway, p21-p27-cyclin E-CDK2 pathway, p14-MDM2-p53 pathway, and ATM-Chk2-CDC25 pathway, respectively. Recent evidence suggests that ovarian cancer is a heterogenous group of neoplasms with several different histologic types, each with its own underlying molecular genetic mechanism. Therefore, expression of cell cycle regulatory proteins should be tested separately according to each histologic type. In serous ovarian carcinoma, high expression of p16, p53, and p27 and low expression of p21 and cyclin E were shown. In addition, this review focuses on the prognostic significance of cell cycle-regulating proteins in EOC. However, it is difficult to compare the results from different groups due to diverse methodologies and interpretations. Accordingly, researchers should establish standardized criteria for the interpretation of immunohistochemical results.

A phase II and pharmacodynamic study of gefitinib in patients with refractory or recurrent epithelial ovarian cancer

BACKGROUND

The primary objective of this study was to evaluate the biochemical effects of gefitinib on its target signal-transduction pathways in patients with recurrent epithelial ovarian cancer (EOC). The secondary objectives included assessing clinical activity and toxicity and determining the association between biochemical and clinical outcomes.

METHODS

Twenty-four heavily pretreated patients with EOC who had good end-organ function and performance status and who had measurable disease received gefitinib 500 mg daily. Prospectively planned core-needle tumor biopsies were obtained before treatment and after 4 weeks. Protein expression of total and phosphorylated (p) epidermal growth factor receptor (EGFR), protein kinase B (AKT), and extracellular regulated kinase (ERK) was quantified in microdissected tumor cells using tissue lysate array proteomics.

RESULTS

All tumor samples had detectable levels of EGFR and p-EGFR. A decrease in the quantity of both EGFR and p-EGFR was observed with gefitinib therapy in >50% of patients. This was not associated with clinical benefit, nor were responses observed. However, trends for increased gastrointestinal and skin toxicity were observed with greater phosphorylation or quantities of EGFR, ERK, and AKT in tumor samples (P </= .05). Gefitinib had limited clinical activity as monotherapy despite documented target inhibition.

CONCLUSIONS

The results from this study demonstrated that gefitinib inhibited the phosphorylation of EGFR in EOC tumor cells, providing proof of target in a clinical setting. Combinatorial therapy with molecular therapeutics against complementary targets may prove successful.

Antiproliferative activity of sulforaphane in Akt-overexpressing ovarian cancer cells

Epidemiologic studies show a correlation between increased consumption of fruits and vegetables with reduced risk of ovarian cancer. One major bioactive compound found in cruciferous vegetables, particularly broccoli, is sulforaphane, derived from the breakdown of glucoraphanin. We observed potent antiproliferative effects of sulforaphane on human ovarian cancer cell line SKOV3 (IC(50) 40 micromol/L) and mouse ovarian cancer cell lines C3 and T3 (IC(50) 25 micromol/L each) by cell viability assays. The loss of viability is reflected by a down-regulation of cell cycle transition regulators cyclin D1, cyclin-dependent kinase 4 (cdk4), and cdk6. The upstream mediators of sulforaphane effects on the cell cycle in ovarian cancer are still unknown. However, because the Akt signal transduction pathway is overactivated in ovarian cancer, we investigated the effects of sulforaphane on this prosurvival pathway. Both total Akt protein and active phosphorylated levels of Akt (Ser(473)) and phosphoinositide 3-kinase were significantly decreased in sulforaphane-treated SKOV3, C3, and T3 cells with a concomitant inhibition of Akt kinase activity by sulforaphane in SKOV3 and C3 cells. This inhibitory effect of sulforaphane leads to a potent induction of apoptosis in all three cell lines, along with the cleavage of poly(ADP)ribose polymerase. Our study is the first to report the antiproliferative effects of sulforaphane in ovarian cancer and identifying the Akt pathway as a target of sulforaphane, with implications for the inhibition of carcinogenesis by diet-based chemoprevention.

Molecular biomarkers for cancer detection in blood and bodily fluids

Cancer is a major and increasing public health problem worldwide. Traditionally, the diagnosis and staging of cancer, as well as the evaluation of response to therapy have been primarily based on morphology, with relatively few cancer biomarkers currently in use. Conventional biomarker studies have been focused on single genes or discrete pathways, but this approach has had limited success because of the complex and heterogeneous nature of many cancers. The completion of the human genome project and the development of new technologies have greatly facilitated the identification of biomarkers for assessment of cancer risk, early detection of primary cancers, monitoring cancer treatment, and detection of recurrence. This article reviews the various approaches used for development of such markers and describes markers of potential clinical interest in major types of cancer. Finally, we discuss the reasons why so few cancer biomarkers are currently available for clinical use.

Thyroid hormone signaling in human ovarian surface epithelial cells

CONTEXT

Ovarian surface epithelial (OSE) cells express multiple nuclear hormone receptor genes, including those encoding thyroid hormone and estrogen receptors (TR and ER, respectively). Ovarian cancer is hormone-dependent, and epidemiological evidence links hyperthyroidism, inflammation of the ovarian surface, and increased risk of ovarian cancer.

OBJECTIVE

The objective of this study was to assess T3 action on human OSE cells in vitro, asking 1) is there evidence for (pre)receptor control, 2) is T3 inflammatory, and 3) does T3 affect ER expression?

DESIGN

Immunohistochemical analysis of fixed human ovaries and in vitro analysis of human OSE primary cell cultures were performed.

PATIENTS

Twelve women aged 29-50 yr (median, 41 yr) undergoing elective gynecological surgery for nonmalignant conditions were studied.

RESULTS

Messenger RNA transcripts for TRalpha1, TRalpha2, TRbeta1, and T3 activating deiodinase 2 and inactivating deiodinase 3 were present in primary OSE cell cultures by RT-PCR. TRalpha and TRbeta proteins were also localized to intact OSE by immunohistochemistry. Treatment of OSE cell cultures for 24 h with T3 caused dose-dependent mRNA expression of inflammation-associated genes: cyclooxygenase-2, matrix metalloproteinase-9, and 11betahydroxysteroid dehydrogenase type 1, determined by quantitative RT-PCR. Finally, treatment with T3 dose dependently stimulated ERalpha mRNA expression without affecting ERbeta1 or ERbeta2.

CONCLUSION

The ovarian surface is a potential T3 target. T3 exerts direct inflammatory effects on OSE cell function in vitro. OSE cell responses to T3 include increased expression of ERalpha mRNA, which encodes the ER isoform most strongly associated with ovarian cancer. This could help explain suggested epidemiological links between hyperthyroidism and ovarian cancer.

Cellular and molecular consequences of peroxisome proliferator-activated receptor-gamma activation in ovarian cancer cells

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a ligand-activated transcription factor. In addition to its canonical role in lipid and glucose metabolism, PPAR-gamma controls cell proliferation, death, and differentiation in several tissues. Here we have examined the expression of PPAR-gamma in ovarian tumors and the cellular and molecular consequences of its activation in ovarian cancer cells. PPAR-gamma was expressed in a large number of epithelial ovarian tumors and cell lines. The PPAR-gamma ligand ciglitazone inhibited the growth and clonogenic survival of ovarian cancer cells, inducing cell cycle arrest and cell death. Growth inhibition by ciglitazone was reversed by the PPAR-gamma antagonist GW9662, indicating the involvement of PPAR-gamma-dependent mechanisms. Microarray-based gene profiling revealed complex changes in the transcriptional program of ovarian cancer cells on treatment with ciglitazone and identified multiple pathways that may contribute to PPAR-gamma ligands' antitumor activity. Genes upregulated by ciglitazone were predominantly associated with metabolic, differentiation, and tumor-suppressor pathways, whereas downregulated genes were involved in cell proliferation, cell cycle, cell organization, and steroid biosynthesis. Collectively, our data indicate that PPAR-gamma activation by selective agonists is a valid strategy for ovarian cancer therapy and prevention, and should be tested alone and in combination with other anticancer drugs.

Ezrin mediates growth and survival in Ewing’s sarcoma through the AKT/mTOR, but not the MAPK, signaling pathway

Recent reports on the role of the membrane-cytoskeleton linker protein ezrin in sarcomas showed an effect on the formation of metastases, dependent on the level of ezrin expression. In this study, we explore the role of ezrin in Ewing's sarcoma, a frequently fatal mesenchymal neoplasm of children and young adults. Through both immunohistochemistry and Western immunoblot studies we find ubiquitous, high-level expression of ezrin in Ewing's sarcoma. In contrast to the observations in osteosarcoma and rhabdomyosarcoma, we demonstrate that inhibition of ezrin-mediated signal transduction, through the expression of a non-phosphorylatable T567A mutant, slows primary growth of Ewing's sarcoma cells in vitro. This reduction in growth is a result of increased apoptosis in the mutant expressing cells. We further show that expression of this mutant reduces the ability of Ewing's sarcoma cells to form experimental metastases in vivo. Molecular examination reveals that the action of ezrin in Ewing's sarcoma is dependent on the AKT/mTOR signal transduction cascade, but not MAP Kinase. These results, therefore, demonstrate that, in Ewing's sarcoma, the biology of ezrin is distinct from that described in other sarcomas. This study further validates ezrin as a potential therapeutic target.

Comparative Proteomics of Ovarian Epithelial Tumors

We analyzed 12 ovarian epithelial tumors using 2D PAGE-based comparative proteomics to construct intra- and inter-tumoral distance map trees and to discover surrogate biomarkers indicative of an ovarian tumor. The analysis was performed after laser microdissection of 12 fresh-frozen tissue samples, including 4 serous, 5 mucinous, and 3 endometrioid tumors, with correlation with their histopathological characteristics. Ovarian epithelial tumors and normal tissues showed an apparent separation on the distance map tree. Mucinous carcinomas were closest to the normal group, whereas serous carcinomas were located furthest from the normal group. All mucinous tumors with aggressive histology were separated from the low malignant potential (LMP) group. The benign-looking cysts adjacent to the intraepithelial carcinoma (IEC) showed an expression pattern identical to that of the IEC area. The extent of change on the lineages leading to the mucinous and serous carcinoma was 1.98-fold different. The overall gene expression profiles of serous or endometrioid carcinomas appeared to be less affected by grade or stage than by histologic type. The potential candidate biomarkers screened in ovarian tumors and found to be significantly up-regulated in comparison to normal tissues were as follows: NM23, annexin-1, protein phosphatase-1, ferritin light chain, proteasome alpha-6, and NAGK (N-acetyl glucosamine kinase). In conclusion, ovarian mucinous tumors are distinct from other ovarian epithelial tumors. LMP mucinous tumors showing histologically aggressive features belong to mucinous carcinoma on the proteomic basis.

Inhibition of phosphatidylinositol 3-kinase sensitizes ovarian cancer cells to carboplatin and allows adjunct chemotherapy treatment

Signal transduction pathways associated with cancer progression and chemotherapeutic resistance are being investigated as molecular targets for chemotherapy. The phosphatidylinositol 3-kinase (PI3K) pathway has been found to be frequently amplified and have increased activity in ovarian cancer. The current study investigates the efficacy of an antagonist of PI3K, LY294002, in inhibiting ovarian cancer cell growth and survival both in vitro and in vivo. The hypothesis tested is that inhibition of PI3K signaling makes ovarian cancer cells susceptible to the effects of platinum-based chemotherapy. Observations show that LY294002 is an effective inhibitor of ovarian cancer cell growth and survival in vitro. Inhibition of PI3K/Akt signaling increased the sensitivity of ovarian cell cultures to the cytotoxic effects of carboplatin. The combined treatment of LY294002 and carboplatin was needed to optimally promote cellular apoptosis and decrease ovarian cancer cell survival in vitro. To extend these observations, a model involving in vivo i.p. growth of human ovarian tumors in a nude mouse was used. LY294002 in combination with carboplatin was more effective in inhibiting ovarian cancer cell xenograft growth than either agent alone. The results of this study suggest that the combined treatment of carboplatin and LY294002 can effectively decrease ovarian tumor progression and support the use of a PI3K inhibitor (e.g., LY294002) as an adjunct platinum-based drug therapy for treatment of ovarian cancer.

Lysophosphatidic acid and endothelin-induced proliferation of ovarian cancer cell lines is mitigated by neutralization of granulin-epithelin precursor (GEP), a prosurvival factor for ovarian cancer

Granulin-epithelin precursor (GEP/progranulin) is an autocrine growth factor for ovarian cancer. We examined the production and function of GEP and report that: (1) GEP production is regulated by endothelin (ET-1), lysophosphatidic acid (LPA), and cAMP; (2) cAMP signals GEP production through exchange protein activated by cAMP (EPAC); (3) ET-1 and cAMP/EPAC induce GEP through ERK1/2; and (4) neutralization of GEP results in apoptosis. Exposure of HEY-A8 and OVCAR3 ovarian cancer cells to LPA and ET-1 yielded GEP production and secretion in a dose- and time-dependent fashion; neither stimulated significant concentrations of cAMP directly. Stimulation of cAMP production with pertussis and cholera toxin, or forskolin induced GEP in a PKA-independent fashion. EPAC, an intracellular cAMP receptor, is activated specifically by the cAMP analog, 8-CPT-2'-O-Me-cAMP (8-CPT); 8-CPT treatment stimulated GEP production and secretion. The MEK inhibitor, U0126, abrogated GEP production in response to ET-1 and 8-CPT, confirming involvement of MAPK. A partial inhibition of basal and stimulated GEP production was observed when cells were treated with a internal calcium chelator, BAPTA. Neutralizing anti-GEP antibody reversed basal as well as LPA, ET-1 and 8-CPT-induced ovarian cancer cell growth and induced apoptosis as demonstrated by caspase-3 and PARP cleavage, DNA fragmentation, and nuclear condensation. These results indicate that GEP is a growth and survival factor for ovarian cancer, induced by LPA and ET-1 and cAMP/EPAC through ERK1/2.

Astrapterocarpan isolated from Astragalus membranaceus inhibits proliferation of vascular smooth muscle cells

The inhibitory effects of astrapterocarpan, formononetin, and calycosin isolated from Astragalus membraneceus on platelet-derived growth factor (PDGF)-BB-induced proliferative response in rat vascular smooth muscle cells (A10 cells) were investigated. Astrapterocarpan significantly inhibited PDGF-BB-induced cell proliferation and DNA synthesis in a concentration-dependent manner. This inhibition was not attributed to toxicity. In contrast, formononetin and calycosin had no effect. We next examined the effect of astrapterocarpan on PDGF-BB signal transduction. Astrapterocarpan inhibited PDGF-BB-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERIC1/2) mitogen-activated protein (MAP) kinase. However, this compound had no effect on phosphorylation of PDGF-beta-receptor, Akt kinase and p38 MAP kinase. These results indicated that astrapterocarpan inhibits PDGF-BB-induced vascular smooth muscle cell proliferation and that this effect may be mediated, at least in part, by inhibition of the ERK1/2 MAP kinase cascade.

The immunomodulatory protein B7-H4 is overexpressed in breast and ovarian cancers and promotes epithelial cell transformation

B7-H4 protein is expressed on the surface of a variety of immune cells and functions as a negative regulator of T cell responses. We independently identified B7-H4 (DD-O110) through a genomic effort to discover genes upregulated in tumors and here we describe a new functional role for B7-H4 protein in cancer. We show that B7-H4 mRNA and protein are overexpressed in human serous ovarian cancers and breast cancers with relatively little or no expression in normal tissues. B7-H4 protein is extensively glycosylated and displayed on the surface of tumor cells and we provide the first demonstration of a direct role for B7-H4 in promoting malignant transformation of epithelial cells. Overexpression of B7-H4 in a human ovarian cancer cell line with little endogenous B7-H4 expression increased tumor formation in SCID mice. Whereas overexpression of B7-H4 protected epithelial cells from anoikis, siRNA-mediated knockdown of B7-H4 mRNA and protein expression in a breast cancer cell line increased caspase activity and apoptosis. The restricted normal tissue distribution of B7-H4, its overexpression in a majority of breast and ovarian cancers and functional activity in transformation validate this cell surface protein as a new target for therapeutic intervention. A therapeutic antibody strategy aimed at B7-H4 could offer an exciting opportunity to inhibit the growth and progression of human ovarian and breast cancers.

Hyaluronan-CD44 interaction with IQGAP1 promotes Cdc42 and ERK signaling, leading to actin binding, Elk-1/estrogen receptor transcriptional activation, and ovarian cancer progression

In this study, we have examined the interaction of hyaluronan (HA)-CD44 with IQGAP1 (one of the binding partners for the Rho GTPase Cdc42) in SK-OV-3.ipl human ovarian tumor cells. Immunological and biochemical analyses indicated that IQGAP1 (molecular mass of approximately 190 kDa) is expressed in SK-OV-3.ipl cells and that IQGAP1 interacts directly with Cdc42 in a GTP-dependent manner. Both IQGAP1 and Cdc42 were physically linked to CD44 in SK-OV-3.ipl cells following HA stimulation. Furthermore, the HA-CD44-induced Cdc42-IQGAP1 complex regulated cytoskeletal function via a close association with F-actin that led to ovarian tumor cell migration. In addition, the binding of HA to CD44 promoted the association of ERK2 with the IQGAP1 molecule, which stimulated both ERK2 phosphorylation and kinase activity. The activated ERK2 then increased the phosphorylation of both Elk-1 and estrogen receptor-alpha (ER alpha), resulting in Elk-1- and estrogen-responsive element-mediated transcriptional up-regulation. Down-regulation of IQGAP1 (by treating cells with IQGAP1-specific small interfering RNAs) not only blocked IQGAP1 association with CD44, Cdc42, F-actin, and ERK2 but also abrogated HA-CD44-induced cytoskeletal function, ERK2 signaling (e.g. ERK2 phosphorylation/activity, ERK2-mediated Elk-1/ER alpha phosphorylation, and Elk-1/ER alpha-specific transcriptional activation), and tumor cell migration. Taken together, these findings indicate that HA-CD44 interaction with IQGAP1 serves as a signal integrator by modulating Cdc42 cytoskeletal function, mediating Elk-1-specific transcriptional activation, and coordinating "cross-talk" between a membrane receptor (CD44) and a nuclear hormone receptor (ER alpha) signaling pathway during ovarian cancer progression.

Proteomics and ovarian cancer: implications for diagnosis and treatment: a critical review of the recent literature

PURPOSE OF REVIEW

Epithelial ovarian cancer is the leading cause of death from gynecologic malignancies amongst American women. Emerging proteomic technologies have promise for early diagnosis and in advancing treatment directions. Application of these technologies has produced new biomarkers, diagnostic approaches, and understanding of disease biology.

RECENT FINDINGS

Mass spectral blood and tissue analysis has yielded new putative biomarkers that require further validation and assessment of diagnostic specificity and sensitivity. Protein signature patterns derived from mass spectrometry datastreams have been modeled and are moving into validation. Tissue-based protein analysis has led to identification of tumor and stromal protein and signal activation events in ovarian cancer. Clinical trials are now ascertaining tissue samples prior to and during therapy with molecularly targeted agents to evaluate modulation of targeted signaling pathways. Finally, proteomic analysis of tissues and metastases will outline biochemical events underlying the metastatic phenotype of ovarian cancer.

SUMMARY

Proteomic approaches are experimental technologies applied to ovarian and other cancers. Proper validation and use of findings may advance our understanding of biochemical events that have complicated successful detection and intervention. This knowledge is the first step in fulfilling the promise of personalized molecular medicine.

Lack of modifying effects of an estrogenic compound atrazine on 7,12-dimethylbenz(a)anthracene-induced ovarian carcinogenesis in rats

The modifying effects of dietary feeding of atrazine, which is one of the endocrine disrupting chemicals (EDCs), on 7,12-dimethylbenz(a)anthracene (DMBA)-induced ovarian carcinogenesis were investigated in female Sprague-Dawley rats. We also assessed the effect of atrazine on proliferating cell nuclear antigen (PCNA)-index and the expression of estrogen receptor (ER)-alpha and -beta and androgen receptor (AR) in induced neoplasms. Rats were given a single injection of DMBA (0.01 ml of 0.5% DMBA suspended in olive oil) into their left ovary to induce ovarian neoplasms. They also received the experimental diet containing 5, 50 or 500 ppm atrazine for 50 weeks, starting one week after the dosing of DMBA. The diets used were free of soy products. DMBA exposure produced left ovarian adenocarcinoma with an incidence of 45% at the end of the study (week 51). Dietary administration atrazine reduced the incidence of ovarian adenocarcinoma: 22, 28, and 26% incidences in rats fed 5, 50, and 500 ppm atrazine containing diets after DMBA exposure, respectively, without statistical significance among the groups. The PCNA-index in adenocarcinomas was greater than that of surface ovarian epithelium. ER-alpha, beta and AR were expressed in a variable percentage of moderately and poorly differentiated adenocarcinoma cell nuclei, but their reactivity was extremely weak or negative in well differentiated adenocarcinoma cells. These results might suggest dietary feeding of a EDC atrazine did not affect DMBA-induced rat ovarian carcinogenesis.