A novel genome-based approach correlates TMPRSS3 overexpression in ovarian cancer with DNA hypomethylation

Objective

In an attempt to analyze more profoundly aberrant DNA hypomethylation in epithelial ovarian cancer (EOC), we applied a novel genome-based approach which includes expression profiling following pharmacologic stimulation of DNA methylation with the methyl donor S-adenosyl-l-methionine (SAM).

Methods

Four different EOC cell lines (OVCAR3, SKOV3, TOV21 and TOV112) were treated with SAM, and gene expression profiling was performed in SAM-treated and control EOC cells. Genes, downregulated upon SAM treatment were considered as potentially hypomethylated in EOC. DNA hypomethylation was independently validated in ovarian tumor and control tissues by bisulfite sequencing PCR (BSP).

Results

Among the genes identified, one of particular interest was the type II serine protease TMPRSS3 gene variants A and D (TMPRSS3-A/D), previously recognized as overexpressed in EOC and representing potential EOC therapeutic targets. Consecutive BSP analysis demonstrated that the common putative promoter region of the TMPRSS3-A/D gene variants was significantly hypomethylated in high-grade serous EOC tumors, compared to low-malignant potential ovarian tumors and normal ovarian tissue.

Conclusions

Our data imply that TMPRSS3-A/D overexpression in EOC is probably due to hypomethylation of their control region thus indicating that TMPRSS3-A/D variants could also represent novel molecular targets for epigenetic therapy of late stages of the disease. Our results also suggest that the frequently observed upregulation of different members of the type II serine proteases gene family in advanced cancer could be due to aberrant DNA hypomethylation. Furthermore, our study introduces a promising discovery approach that could be used for the identification of hypomethylated genes in different experimental cell models.     

Costunolide induces apoptosis in platinum-resistant human ovarian cancer cells by generating reactive oxygen species

Objective

The acquired resistance to platinum-based drugs has become an obstacle in the management of ovarian cancer. We investigated the apoptosis-inducing effect of costunolide, a natural sesquiterpene lactone, in platinum-resistant human ovarian cancer cells, along with the molecular mechanism of action.

Methods

Costunolide and cisplatin were examined in platinum-resistant human ovarian cancer cells. MTT assay for cell viability, PI staining for cell cycle profiling, and Annexin V assay for apoptosis analysis. ROS production and protein expression was assessed by H₂DCFDA staining and Western blotting, respectively. Combination effect was determined using the Combination Index (CI) method.

Results

It was found that costunolide is more potent than cisplatin in inhibiting cell growth in three platinum-resistant ovarian cancer cell lines (MPSC1^PT, A2780^PT, and SKOV3^PT). Costunolide induced apoptosis of platinum-resistant cells in a time- and dose-dependent manner and suppressed tumor growth in SKOV3^PT-bearing mouse model. In addition, costunolide triggered the activation of caspase-3, -8, and -9. Pretreatment with caspase inhibitors neutralized the pro-apoptotic activity of costunolide. We further demonstrated that costunolide induced a significant increase in intracellular reactive oxygen species (ROS). Additionally, the antioxidant N-acetyl-L-cysteine (NAC) significantly attenuated the costunolide-induced production of ROS, activation of caspases, down-regulation of Bcl-2, and apoptosis in platinum-resistant ovarian cancer cells. Moreover, costunolide synergized with cisplatin to induce cell death in platinum-resistant ovarian cancer cells.

Conclusions

Taken together, these data suggest that costunolide, alone or in combination with cisplatin, may be of therapeutic potential in platinum-resistant ovarian cancer.     

Expression of 67-kDa laminin receptor was associated with tumor progression and poor prognosis in epithelial ovarian cancer

Objective

67-kDa laminin receptor (67LR) has been identified as a prognostic biomarker for a variety of human cancers. We investigated the clinical significance of 67LR expression and its functional role in epithelial ovarian cancer (EOC).

Methods

67LR expression was evaluated by immunohistochemistry in 62 patients with EOC. We assessed the correlation of 67LR expression with clinical characteristics. In vitro experiment was performed for 67LR with inhibition using siRNA to evaluate its role in cell survival, apoptosis, and invasion in EOC cells.

Results

67LR was predominantly expressed on the cell membrane in the majority of EOC samples (45/62, 73%). 67LR expression was significantly correlated with advanced stage (P = 0.001). Patients with 67LR expression had shorter progression-free survival among all the patients (P = 0.010) and in particular among patients with advanced stages (P = 0.046). When 67LR expression was inhibited by siRNA in EOC cells (HeyA8 and A2780), there was a significant decrease of cell proliferation and invasion as well as increase of apoptosis.

Conclusion

These findings suggest that 67LR expression may play an important role in tumor progression into advanced stage with poor prognosis in EOC and down-regulation of 67LR on tumor cells may be a therapeutic target in those patients.     

Tyrosine kinase A receptor (trkA): a potential marker in epithelial ovarian cancer

Objectives

To evaluate the role of trkA receptor as a potential tumor marker in serous epithelial ovarian cancer and its relationship with the angiogenic factors expression as vascular endothelial growth factor (VEGF) and nerve growth factor (NGF). Additionally, to examine whether NGF and VEGF secreted by epithelial ovarian cancer (EOC) explants and from epithelial ovarian cancer cell line (A2780) are involved in the process of angiogenesis, such as cellular proliferation, migration and differentiation of the human endothelial cell line (EA.hy926).

Methods

The mRNA levels of VEGF, NGF and trkA receptors were measured using PCR in 60 ovarian samples. Cellular localization and semi-quantitative estimation of VEGF, NGF, total trkA and p-trkA was performed using IHC in epithelial cells. NGF, total trkA and p-trkA protein were also evaluated in endothelial cells from the same tissues. Human endothelial cell line EA.hy926 was cultured with conditioned media obtained from both EOC explants and from the A2780 cell line, with or without NGF stimulus.

Results

Significantly higher levels of NGF, total trkA and p-trkA protein expressions were observed in epithelial and endothelial cells in poorly differentiated EOC versus normal ovary. Interestingly, the p-trkA receptor expression level showed the most significant difference and its presence was only found in borderline tumor and EOC samples indicating the importance of trkA receptor in EOC as a potential tumor marker.A significant increase in proliferation, migration and differentiation of EA.hy926 cells was observed with NGF, and this effect was significantly reverted when NGF was immuno-blocked and when a trkA inhibitor was used, showing that NGF is an important angiogenic factor in EOC by activating its trkA receptor.

Conclusion

These results indicate that p-trkA may be considered as a new potential tumor marker in EOC, and that NGF may also act as a direct angiogenic factor in EOC.     

Luteinizing hormone upregulates survivin and inhibits apoptosis in ovarian epithelial tumors

Objective

Luteinizing hormone (LH) plays an important role in the development of ovarian cancer, and has been shown to inhibit apoptosis in ovarian cancer cells. Similarly, survivin is a molecule that has been shown to inhibit apoptosis in other types of cancer. Therefore, the aim of this study was to determine whether survivin can be induced by LH in ovarian cancer, and whether this induction influences the sensitivity of ovarian cancers to chemotherapy.

Study design

Survivin expression was monitored using western blot assays, and flow cytometry was used to detect the effects of cisplatin on the induction of apoptosis by LH. MTT assays were also used to analyze rates of cell proliferation.

Results

Administration of LH in vitro induced survivin expression in a dose-dependent manner. Moreover, this signaling was dependent on the ERK1/2 signaling pathway. LH also blocked apoptosis induced by cisplatin.

Conclusion

These results suggest that LH influences the sensitivity of ovarian cancer cells to chemotherapy via signaling to inhibit apoptosis that also upregulates survivin.     

Clear cell carcinoma of the ovary: a review of the literature

Objective

Different histologic types of epithelial ovarian cancer may represent different diseases with unique clinical and molecular characteristics. Clear cell carcinoma (CCC) of the ovary has been reported as having a worse prognosis than high grade serous epithelial ovarian cancer (EOC). This article critically reviews the literature pertinent to the pathology, pathogenesis, diagnosis, management, and outcome of patients with ovarian CCC.

Methods

MEDLINE was searched for all research articles published in English between January 01, 1977 and January 30, 2012 which reported on patients diagnosed with ovarian CCC. Given the rarity of this tumor, studies were not limited by design or number of reported patients.

Results

Ovarian CCC tumors represent 5-25% of ovarian cancers. Its histologic diagnosis can be challenging, resulting often times in misclassification of these tumors. Ovarian CCC tends to present at earlier stages and has been associated with endometriosis, ARID1A and PIK3CA mutations. When compared to stage-matched controls, patients with early-stage ovarian CCCs may have a better prognosis than patients with high-grade serous tumors. For those with advanced stage disease, high-grade serous histology confers a better prognosis than ovarian CCC. Patients with Stage IC-IV have a relatively poor prognosis and efforts should center in discovery of more effective treatment strategies.

Conclusions

Ovarian CCC is a biologically distinct entity, different from high-grade serous EOC. Future studies should explore the role of targeted therapies in the management of ovarian CCC.     

RhoB mediates antitumor synergy of combined ixabepilone and sunitinib in human ovarian serous cancer

Objective

The aim was to evaluate antitumor activity of the combination of ixabepilone and sunitinib in pre-clinical models of chemotherapy naïve and refractory epithelial ovarian tumors, and to investigate the mechanism of synergy of such drug combination.

Methods

HOVTAX2 cell line was derived from a metastatic serous papillary epithelial ovarian tumor (EOC) and a paclitaxel-resistant derivative was established. Dose response curves for ixabepilone and sunitinib were generated and synergy was determined using combination indexes. The molecular mechanism of antitumor synergy was examined using shRNA silencing.

Results

The combination of ixabepilone and sunitinib demonstrated robust antitumor synergy in naïve and paclitaxel-resistant HOVTAX2 cell lines due to increased apoptosis. The GTPase, RhoB, was synergistically upregulated in cells treated with ixabepilone and sunitinib. Using shRNA, RhoB was demonstrated to mediate antitumor synergy. These results were validated in two other EOC cell lines.

Conclusions

Ixabepilone plus sunitinib demonstrated antitumor synergy via RhoB in naïve and paclitaxel-resistant cells resulting in apoptosis. This study demonstrates a novel mechanism of action leading to antitumor synergy and provides ‘proof-of-principle’ for combining molecular targeted agents with cytotoxic chemotherapy to improve antitumor efficacy. RhoB could be envisioned as an early biomarker of response to therapy in a planned Phase II clinical trial to assess the efficacy of ixabepilone combined with a receptor tyrosine kinase inhibitor such as sunitinib. To the best of our knowledge, this is the first demonstration of antitumor synergy between these two classes of drugs in EOC and the pivotal role of RhoB in this synergy.     

Androgen receptor expression is a biological marker for androgen sensitivity in high grade serous epithelial ovarian cancer

Objectives

In the present study we explore the effects of androgens and anti-androgens on primary cultures of EOC cells. We also investigate the effects of chemotherapy on AR expression. Epithelial ovarian cancer (EOC) arises from ovarian surface epithelial cells (OSE), which express the androgen receptor (AR). Androgen stimulation of OSE cells results in increased proliferation and protection from apoptosis. Nevertheless, in clinical trials anti-androgens have had a low objective response rate in relapsed ovarian cancer.

Methods

1. Androgen receptor (AR) expression and response to androgenic stimulation were correlated in primary ovarian cancer cells derived from ascitic fluid from patients with advanced ovarian cancer,2. AR expression in primary epithelial ovarian cancer was investigated before and after chemotherapy using paired histological samples which had been incorporated into a tissue microarray.

Results

Eleven primary ovarian cancer cultures were established from ascitic fluid. There was wide variation of expression of androgen receptor mRNA between cultures. Cell division increased after dihydro-testosterone (DHT) stimulation in 6 out of 11 primary cultures. The fraction of cells in S-phase increased from 4.4% in cells grown in serum-free medium to 8.3% in cells stimulated with 100 nM of DHT (P < 0.001). The increase in S-phase fraction was abrogated after treatment with the anti-androgen, bicalutamide in 4 out of 5 responsive cultures. There was a strong correlation (r² = 0.7) between nuclear AR expression by immunohistochemistry and S-phase fraction changes in primary cultures.Paired pre- and post-chemotherapy histological samples from 29 patients were incorporated into a tissue microarray (TMA). Nuclear and cytoplasmic AR expression by immunohistochemistry (IHC) decreased significantly after chemotherapy (P < 0.01).

Conclusion

AR expression correlates with increased S-phase fraction in response to androgenic stimulation. Immunohistochemical analysis of AR expression needs to be further tested in clinical trials to select AR positive EOC for anti-androgen therapy. Anti-androgen use early in the course of ovarian cancer is more likely to be effective as these data suggest that androgen receptor expression decreases with exposure to chemotherapy and this may explain the low response rates seen in clinical trials of patients heavily pre-treated with multiple courses of chemotherapy.     

A phase II evaluation of lapatinib in the treatment of persistent or recurrent epithelial ovarian or primary peritoneal carcinoma: a gynecologic oncology group study

Objective

Activation and dimerization of the ERBB family play a role in the pathogenesis and progression of ovarian cancer. We conducted a phase II trial to evaluate the activity and tolerability of lapatinib in patients with recurrent or persistent epithelial ovarian cancer (EOC) and to explore the clinical value of expression levels of epidermal growth factor receptors (EGFR), phosphorylated EGFR, HER-2/neu, and Ki-67, and the presence of EGFR mutations.

Methods

Eligible patients had recurrent or persistent EOC or primary peritoneal carcinoma, measurable disease, and up to 2 prior chemotherapy regimens for recurrent disease. Patients were treated with lapatinib 1500 mg/day. The primary endpoint of efficacy was 6-month progression free survival (PFS).

Results

Twenty-five of 28 patients were eligible and evaluable for analysis of efficacy and toxicity. Two (8.0%) were alive and progression-free at 6 months. No objective responses were observed. There were 1 grade 4 toxicity (fatigue) and few grade 3 toxicities. Associations between Ki-67 with prior platinum-free interval, PFS, and a polymorphism in EGFR were suggested.

Conclusions

Lapatinib has minimal activity in recurrent ovarian cancer. Ki-67 expression may be associated with prior PFS and a polymorphism in EGFR exon 20 (2361G>A, Q787Q).     

Elafin selectively regulates the sensitivity of ovarian cancer cells to genotoxic drug-induced apoptosis

Objective

Elafin has been reported to be abundantly expressed in human epithelial ovarian carcinoma (EOC), however, its functions are poorly understood. Here, we evaluated the role of elafin in modulating the sensitivity of human EOC cells to chemotherapeutic drugs.

Methods

Elafin expression was determined by ELISA in 9 established human EOC cell lines. A lentivirus encoding elafin-specific shRNA was used to down-regulate elafin expression in OVCAR3 and OV433 cells, and a plasmid encoding elafin was used to ectopically express elafin in elafin-negative SKOV3 cells. Sensitivity to cisplatin and other genotoxic agents and to paclitaxel, an inhibitor of microtubule depolymerization, was examined in OVCAR3, OV433 and SKOV3 sublines. Cell viability was determined by the MTT assay, apoptosis by annexin V/7-AAD staining and caspase activation by fluorimetric assay.

Results

Knockdown of the elafin gene decreases cisplatin IC50 by at least 2-folds in OVCAR3 and OVCAR433 cells (p < 0.01) but does not affect paclitaxel IC50. The sensitivity to other genotoxic agents such as carboplatin, cyclophosphamide and 5-fluorouracil was also increased by silencing the expression of elafin. Apoptosis and caspase-3 activation were significantly augmented in cisplatin-treated OVCAR3 cells with silenced elafin. Overexpression of elafin in SKOV3 cells made them more resistant to cisplatin and decreased cisplatin-induced apoptosis and caspase activation (p < 0.01).

Conclusions

Expression of elafin decreases the sensitivity of human EOC cells to several genotoxic agents, which may have an important implication in predicting the response of patients with EOC to chemotherapy in the clinic.     

Nomogram for predicting 5-year disease-specific mortality after primary surgery for epithelial ovarian cancer

Objective

To develop a nomogram based on established prognostic factors to predict the probability of 5-year disease-specific mortality after primary surgery for patients with all stages of epithelial ovarian cancer (EOC) and compare the predictive accuracy with the currently used International Federation of Gynecology and Obstetrics (FIGO) staging system.

Methods

Using a prospectively kept database, we identified all patients with EOC who had their primary surgery at our institution between January 1996 and December 2004. Disease-specific mortality was estimated using the Kaplan-Meier method. Twenty-eight clinical and pathologic factors were analyzed. Significant factors on univariate analysis were included in the Cox proportional hazards regression model, which identified factors utilized in the nomogram. The concordance index (CI) was used as an accuracy measure, with bootstrapping to correct for optimistic bias. Calibration plots were constructed.

Results

A total of 478 patients with EOC were included. The most predictive nomogram was constructed using seven variables: age, FIGO stage, residual disease status, preoperative albumin level, histology, family history suggestive of hereditary breast/ovarian cancer (HBOC) syndrome, and American Society of Anesthesiologists (ASA) status. This nomogram was internally validated using bootstrapping and shown to have excellent calibration with a bootstrap-corrected CI of 0.714. The CI for FIGO staging alone was significantly less at 0.62 (P = 0.002).

Conclusion

We have developed an all-stage nomogram to predict 5-year disease-specific mortality after primary surgery for epithelial ovarian cancer. This tool is more accurate than FIGO staging and should be useful for patient counseling, clinical trial eligibility, postoperative management, and follow-up.     

nm23 gene polymorphisms are associated with survival of patients with epithelial ovarian cancer but not with susceptibility to disease

Objective

nm23, a tumor metastasis suppressor gene, has been linked to protection against tumorigenesis and tumor metastasis. This study evaluated whether genetic variants in the nm23 gene were associated with susceptibility to epithelial ovarian cancer (EOC) or the clinical outcome of patients.

Methods

A case-control study was performed with 302 patients with epithelial ovarian cancer and 302 control women. According to the genotypes, the outcome in 213 EOC patients was compared. Progression-free survival (PFS) and overall survival (OS) were analyzed with Kaplan-Meier plots and Cox models adjusted for clinical factors.

Results

The case-control analysis showed that the rs16949649 and rs2302254 polymorphisms in the nm23 gene promoter were not associated with the risk of developing EOC. In contrast, survival analysis showed that the rs2302254 C/T polymorphism was related to the prognosis of EOC patients. Compared with patients carrying the C/C genotype, patients carrying the T/T genotype had a shorter median PFS and median OS by Kaplan-Meier plots and Cox models adjusted for clinical factors. For rs16949649 T/C polymorphisms, Kaplan-Meier analysis indicated that patients carrying the homozygous C/C genotype had shorter PFS and OS than those carrying the T allele (T/T + T/C genotype). The Cox proportional hazard model analysis suggested that this relationship was only retained in OS when adjusted for clinical factors.

Conclusion

Our studies suggest that rs16949649 and rs2302254 polymorphisms in the nm23 gene promoter may influence the prognosis of patients with epithelial ovarian cancer.     

Myxoma virus-mediated oncolysis of ascites-derived human ovarian cancer cells and spheroids is impacted by differential AKT activity

Objective

We propose that metastatic epithelial ovarian cancer (EOC) is a potential therapeutic target for the oncolytic agent, Myxoma virus (MYXV).

Methods

Primary EOC cells were isolated from patient ascites and cultured as adherent cells or in suspension using Ultra Low-Attachment dishes. MYXV expressing green fluorescent protein was used to infect cells and spheroids. Infection was monitored by fluorescence microscopy, viral titering and immunoblotting for M-T7 and M130 virus protein expression, and cell viability by alamarBlue assay. Akti-1/2 (5 μM) and rapamycin (20 nM) were used to assay the role of PI3K-AKT signaling in mediating MYXV infection.

Results

Ascites-derived EOC cells grown in adherent culture are effectively killed by MYXV infection. EOC cells grown in suspension to form three-dimensional EOC spheroids readily permit MYXV entry into cells, yet are protected from the cytopathic effects of late MYXV infection. Upon reattachment (to model secondary metastasis), EOC spheroids are re-sensitized to MYXV-mediated oncolysis. The critical determinant that facilitates efficient MYXV infection is the presence of an activated PI3K-AKT signaling pathway. Treatment with the specific AKT inhibitor Akti-1/2 reduces infection of monolayer EOC cells and spheroids. Direct infection of freshly-collected ascites demonstrated that 54.5% of patient samples were sensitive to MYXV-mediated oncolytic cell killing. We also demonstrate that factor(s) present in ascites may negatively impact MYXV infection and oncolysis of EOC cells, which may be due to a down-regulation in endogenous AKT activity.

Conclusions

Differential activity of AKT serves as the mechanistic basis for regulating MYXV-mediated oncolysis of EOC spheroids during key steps of the metastatic program. In addition, we provide the first evidence that MYXV oncolytic therapy may be efficacious for a significant proportion of ovarian cancer patients with metastatic disease.     

Inhibition of cell growth and induction of apoptosis in ovarian carcinoma cell lines CaOV3 and SKOV3 by natural withanolide Withaferin A

Objective

Withaferin A, a natural withanolide, has shown anti-cancer properties in various cancers including breast cancer, but its effects in ovarian cancer remain unexplored. Notch 1 and Notch3 are critically involved in ovarian cancer progression. We decided to examine the effects of Withaferin A in ovarian carcinoma cell lines and its molecular mechanism of action including its regulation of Notch.

Methods

The effects of Withaferin A were examined in CaOV3 and SKOV3 ovarian carcinoma cell lines using MTS assay, clonogenic assay, annexin V/propidium iodide flow cytometry, and cell cycle analysis. Western analysis was conducted to examine the molecular mechanisms of action.

Results

Withaferin A inhibited the growth and colony formation of CaOV3 and SKOV3 cells by inducing apoptosis and cell cycle arrest. These changes correlated with down-regulation of Notch1, Notch3, cdc25C, total and phosphorylated Akt, and bcl-2 proteins.

Conclusions

Withaferin A inhibits CaOV3 and SKOV3 ovarian carcinoma cell growth, at least in part by targeting Notch1 and Notch3.     

Prevalence of cysts in epithelial ovarian cancer

Objective

Ovarian carcinomas mostly appear as large cystic masses. However, the exact prevalence of cysts in epithelial ovarian cancer (EOC) has never been documented as well as the tumor factors that are related to the presence of cysts. Demonstrating the prevalence of cysts in EOC is essential for research focused on predictive and prognostic biomarkers in ovarian cyst fluid.

Study design

From 233 patients with primary EOC who underwent surgery, pathological data were collected from pathology reports. Univariate and multivariate logistic regression were used to analyze the relationship between the presence of cysts and other tumor characteristics.

Results

Cysts in EOC were present in 83.7% of the patients and were mostly (61%) multilocular. The most common histological subtypes (serous, mucinous, endometrioid, clear cell) contained cysts in more than 85% of the cases. In univariate regression analysis, early FIGO stage, low tumor grade and a large tumor size were significantly associated with the presence of cysts (OR (95% CI) = 5.312 (1.81-15.57), 6.906 (2.31-20.66) and 1.169 (1.08-1.27), respectively). In multivariate regression analysis, apart from tumor size, only tumor grade was independently associated with the presence of cysts (adjusted OR (95% CI) = 4.234 (1.36-13.22)).

Conclusions

The large majority of all EOCs contained cysts. Histological subtype, FIGO stage, tumor necrosis and age were not associated with the presence of cystic EOC. In contrast, tumor grade and tumor size were independently related to the presence of cystic EOC. This means that cystic EOCs represent a subgroup of larger and more well-differentiated tumors. The evident relationship between the presence of cysts and differentiation grade is interesting from a clinical point of view as grading is especially important for the prognosis and treatment of patients with stage I EOC.     

Prognosis of ovarian clear cell carcinoma compared to other histological subtypes: a meta-analysis

Objective

To compare the survival outcome between clear cell carcinoma (CCC) and other histological subtypes in epithelial ovarian carcinoma (EOC).

Methods

From January 1974 to February 2011, we identified a total of 31,800 (CCC; 2152, non-CCC; 29648) patients from 12 studies meeting the inclusion criteria.

Results

Heterogeneity tests demonstrated significant between-study variation (I² = 92.1%) with no significant difference in hazard ratio (HR) for death between CCC and non-CCC (HR; 1.16, 95% CI; 0.85-1.57, random-effects model). Comparing the HR based on stage I + II, and stage III + IV, between CCC and non-CCC, showed that CCC patients had a higher hazard rate for death than those with non-CCC of the ovary (stage I + II; HR; 1.17, 95% CI; 1.01-1.36, stage III + IV; HR; 1.65, 95% CI; 1.52-1.79). In a comparison of CCC and serous EOC, advanced stage (III and IV) CCC only showed a poorer hazard rate for death than serous EOC (HR; 1.71, 95% CI; 1.57-1.86).

Conclusion

This analysis suggests that ovarian CCC patients had poorer prognosis than those with other histological subtypes of EOC, especially in advanced EOC stages. Different treatment strategies may be needed for patients with ovarian CCC.     

Side population is increased in paclitaxel-resistant ovarian cancer cell lines regardless of resistance to cisplatin

Objectives

In recent years, cancer stem cells (CSCs) have been reported to be correlated with chemoresistance and may also be enriched in side populations (SPs). In this study, the relationship between resistance to paclitaxel (PTX) and cisplatin (CDDP) and side populations was examined in three parental PTX- and CDDP-sensitive ovarian cancer cell lines (2008, KF28, and TU-OM-1) and several other cell lines derived from these as well as the additional effects of interferon-alpha (INF-α).

Methods

SP of three different parental cell lines and PTX- and/or CDDP-resistant cell lines derived from these was analyzed with flow cytometry. The expression of ABCB1 and ABCG2 in KF28 and its derived cell lines was examined. Additional cell-death effect of INF-α with PTX was also examined.

Results

In the three parental cell lines and the PTX-sensitive cell lines derived from these lines, SP was very low. Conversely, in PTX-resistant cell lines, regardless of CDDP resistance, SP increased. ABCB1 was strongly expressed in the PTX-resistant cells, but not in their parental lines, which are sensitive to PTX. While INF-α showed only slight enhancement of the cell-death effect of PTX in PTX-sensitive cells, INF-α itself strongly induced apoptosis in PTX-resistant cells regardless of PTX concentration.

Conclusions

The SP could be correlated with resistance to PTX. SP could be a target of INF-α, and resistance to PTX might be overcome by INF-α.     

Carcinosarcoma of the ovary: a review of the literature

Objective

Carcinosarcoma of the ovary is a rare tumor with a grim prognosis. This article critically reviews the literature pertinent to the pathology, pathogenesis, diagnosis, management, and outcome of patients with ovarian carcinosarcoma (OCS).

Methods

MEDLINE was searched for all research articles published in English between January 1, 1981 and August 30, 2011 which reported on patients diagnosed with carcinosarcoma of the ovary. Given the rarity of this tumor, studies were not limited by design or number of reported patients.

Results

Patients with OCS generally present with advanced stage disease, and symptoms similar to those of patients with epithelial ovarian cancer (EOC). Retrospective studies have shown that cytoreductive surgery improves outcomes in patients with OCS. Similarly, platinum-based chemotherapy appears to be active in the treatment of OCS.

Conclusions

Ovarian carcinosarcomas are rare and aggressive tumors, associated with a poor prognosis. The mainstay of treatment remains cytoreductive surgical effort for metastatic disease followed by platinum-based chemotherapy. The role of targeted therapies may be promising in the treatment of OCS.     

Cytoplasmic expression of estrogen receptor beta (ERβ) predicts poor clinical outcome in advanced serous ovarian cancer

Objective

In this study we investigated the prognostic value of estrogen receptor α (ERα), ERβ and progesterone receptor (PR) expression in 58 untreated advanced serous ovarian cancer patients. The study also included 12 macroscopically and histopathologically normal ovaries.

Materials and methods

Protein expression was evaluated by immunohistochemistry, and antibody staining detected in both the nuclear and cytoplasmic compartments was taken into account. Immunopositivity was analyzed in relation to tumor clinicopathological variables, disease-free survival (DFS), and overall survival (OS).

Results

Epithelial cells in ovarian cancer tissue showed significantly lower levels of nuclear ERβ and PR, but not ERα, than in normal ovarian tissue. In the case of ERβ, however, while normal ovarian epithelium exhibited almost exclusively strong nuclear staining, ovarian cancer tissue mostly showed cytoplasmic immunopositivity. Nuclear ERα and ERβ expression were not associated with clinical outcome. Conversely, any cytoplasmic ERβ expression was an independent unfavorable prognostic factor for DFS, a finding approaching statistical significance also for OS. These data suggest that, in advanced serous ovarian cancer, cytoplasmic ERβ signaling may be more important for patient survival than its nuclear signaling. In the case of PR, positivity was an independent favorable prognostic factor for DFS.

Conclusions

These novel findings, that need to be confirmed in a large prospective trial, suggest that additional prognostic, and possibly therapeutic opportunities may be available in advanced serous ovarian cancer.     

Glucose deprivation activates AMPK and induces cell death through modulation of Akt in ovarian cancer cells

Objectives

Upregulation of glycolysis has been demonstrated in multiple tumor types. Glucose deprivation results in diminished intracellular ATP; this is counteracted by AMPK activation during energy deficiency to restore ATP levels. We sought to determine whether glucose deprivation could induce cytotoxicity in ovarian cancer cells through activation of AMPK, and whether AMPK activators could mimic glucose deprivation induced cytotoxicity.

Methods

Sensitivity to 2DG induced cytotoxicity and glucose deprivation was determined in a panel of ovarian cancer cells. Cellular growth rate, rate of glucose uptake, and response to glucose deprivation were determined. Expression of Glut-1, HIF1-α, AMPK and Akt was determined by immunoblotting.

Results

Incubation of ovarian cancer cells with glucose-free media, 2-DG and AMPK activators resulted in cell death. The glycolytic phenotype of ovarian cancer cells was present in both normoxic and hypoxic conditions, and did not correlate with HIF1-α expression levels. Sensitivity to glucose deprivation was independent of growth rate, rate of glucose uptake, and appeared to be dependent upon constitutive activation of Akt. Glucose deprivation resulted in activation of AMPK and inhibition of Akt phosphorylation. Treatment with AMPK activators resulted in AMPK activation, Akt inhibition, and induced cell death in ovarian cancer cells.

Conclusions

Ovarian cancer cells are glycolytic as compared to normal, untransformed cells, and are sensitive to glucose deprivation. Because ovarian cancer cells are dependent upon glucose for growth and survival, treatment with AMPK activators that mimic glucose deprivation may result in broad clinical benefits to ovarian cancer patients.