Implication of malignancy and prognosis of p27(kip1), Cyclin E, and Cdk2 expression in epithelial ovarian tumors

The Clinicopathological Significance of the Cyclin D1/E1-Cyclin-Dependent Kinase (CDK2/4/6)-Retinoblastoma (RB1/pRB1) Pathway in Epithelial Ovarian Cancers

Cyclin-dependent kinases (CDK2, CDK4, CDK6), cyclin D1, cyclin E1 and phosphorylated retinoblastoma (pRB1) are key regulators of the G1/S cell cycle checkpoint and may influence platinum response in ovarian cancers. CDK2/4/6 inhibitors are emerging targets in ovarian cancer therapeutics. In the current study, we evaluated the prognostic and predictive significance of the CDK2/4/6-cyclin D1/E1-pRB1 axis in clinical ovarian cancers (OC). The CDK2/4/6, cyclin D1/E1 and RB1/pRB1 protein expression were investigated in 300 ovarian cancers and correlated with clinicopathological parameters and patient outcomes. CDK2/4/6, cyclin D1/E1 and RB1 mRNA expression were evaluated in the publicly available ovarian TCGA dataset. We observed nuclear and cytoplasmic staining for CDK2/4/6, cyclins D1/E1 and RB1/pRB1 in OCs with varying percentages. Increased nuclear CDK2 and nuclear cyclin E1 expression was linked with poor progression-free survival (PFS) and a shorter overall survival (OS). Nuclear CDK6 was associated with poor OS. The cytoplasmic expression of CDK4, cyclin D1 and cyclin E1 also has predictive and/or prognostic significance in OCs. In the multivariate analysis, nuclear cyclin E1 was an independent predictor of poor PFS. Tumours with high nuclear cyclin E1/high nuclear CDK2 have a worse PFS and OS. Detailed bioinformatics in the TCGA cohort showed a positive correlation between cyclin E1 and CDK2. We also showed that cyclin-E1-overexpressing tumours are enriched for genes involved in insulin signalling and release. Our data not only identified the prognostic/predictive significance of these key cell cycle regulators but also demonstrate the importance of sub-cellular localisation. CDK2 targeting in cyclin-E1-amplified OCs could be a rational approach.

Scutellaria baicalensis Georgi and Their Natural Flavonoid Compounds in the Treatment of Ovarian Cancer: A Review

Ovarian cancer (OC) is one of the most common types of cancer in women with a high mortality rate, and the treatment of OC is prone to high recurrence rates and side effects. Scutellaria baicalensis (SB) is a herbal medicine with good anti-cancer activity, and several studies have shown that SB and its flavonoids have some anti-OC properties. This paper elucidated the common pathogenesis of OC, including cell proliferation and cell cycle regulation, cell invasion and metastasis, apoptosis and autophagy, drug resistance and angiogenesis. The mechanisms of SB and its flavonoids, wogonin, baicalein, baicalin, Oroxylin A, and scutellarein, in the treatment of OC, are revealed, such as wogonin inhibits proliferation, induces apoptosis, inhibits invasion and metastasis, and increases the cytotoxicity of the drug. Baicalein also inhibits vascular endothelial growth factor (VEGF) expression etc. Analyzing their advantages and disadvantages in treating OC provides a new perspective on the role of SB and its flavonoids in OC treatment. It serves as a resource for future OC research and development.

SCUBE3 downregulation modulates hepatocellular carcinoma by inhibiting CCNE1 via TGFβ/PI3K/AKT/GSK3β pathway

OBJECTIVES

We aimed to verify the role of signal peptide-CUB-EGF-like domain-containing protein3 (SCUBE3) in the hepatocellular carcinoma (HCC) progression.

METHODS

The role of SCUBE3 in HCC cell proliferation, apoptosis, and cell cycle in vitro were detected using MTT assay, colony formation assay, 5-ethynyl-2´-deoxyuridine assay (EDU), Celigo cell counting assay, Caspase3/7 activity assay, and flow cytometry. The effect of SCUBE3 on HCC cell proliferation in vivo was inspected by a xenograft tumour model in nude mice. The related mechanisms were further studied.

RESULTS

The level of SCUBE3 was upregulated in HCC tissues and cell lines. Knockdown of SCUBE3 inhibited proliferation, promoted apoptosis, and induced cell cycle arrest in HCC cell lines in vitro and in vivo. Screening of cell cycle-related proteins revealed that CCNL2, CDK6, CCNE1, and CCND1 exhibited a significantly different expression profile. We found that SCUBE3 may promote the proliferation of HCC cells by regulating CCNE1 expression. The pathway enrichment analysis showed that the TGFβ signalling pathway and the PI3K/AKT signalling pathway were significantly altered. Co-immunoprecipitation results showed that SCUBE3 binds to the TGFβRII receptor. SCUBE3 knockdown inhibited the PI3K/AKT signalling pathway and the phosphorylation of GSK3β to inhibit its kinase activity.

CONCLUSIONS

SCUBE3 promotes HCC development by regulating CCNE1 via TGFβ/PI3K/AKT/GSK3β pathway. In addition, SCUBE3 may be a new molecular target for the clinical diagnosis and treatment of HCC.

Up-regulation of GSTT1 in serous ovarian cancer associated with resistance to TAXOL / carboplatin

Serous ovarian cancer (SOC) is the most common women cancer and the leading cause of cancer-related mortality among the gynaecological malignancies. Although effective chemotherapeutics combined with surgery are developed for the treatment, the five-year survival rate is unsatisfactory due to chemoresistance. To overcome this shortcoming of chemotherapy, we established taxol and carboplatin resistant SOC cell lines for the understandings of the molecular and cellular mechanisms of chemoresistance. Here, we found that these chemoresistant cell lines showed less viability and proliferation, due to more cells arrested at G0/G1 phase. Glutathione-S-transferases-theta1 (GSTT1) was significantly upregulated in these chemoresistant cells, along with other chemoresistant genes. Meanwhile, GSTT1 expression was also significantly upregulated in the SOC patient tissues after taxol treatment, indicating this upregulation was physiologically relevant to chemotherapy. Further, suppression of GSTT1 expression by shRNA in SOC cell lines led to more sensitivity to drug treatment, through increasing divided cells and promoting cell death. Moreover, the expression of DNA topoisomerase 1 (Topo I) was in synergy with that of GSTT1 in the chemoresistant cells, and GSTT1 can bind to Topo I in vitro, which suggested GSTT1 could function through DNA repair mechanism during chemoresistance. In summary, our data imply that GSTT1 may be a potential biomarker or indicator of drug resistance in serous ovarian cancer.

Inhibition of CDK4/6 as Therapeutic Approach for Ovarian Cancer Patients: Current Evidences and Future Perspectives

Simple Summary

Altered regulation of the cell cycle is a hallmark of cancer. The recent clinical success of the inhibitors of CDK4 and CDK6 has convincingly demonstrated that targeting cell cycle components may represent an effective anti-cancer strategy, at least in some cancer types. However, possible applications of CDK4/6 inhibitors in patients with ovarian cancer is still under evaluation. Here, we describe the possible biological role of CDK4 and CDK6 complexes in ovarian cancer and provide the rationale for the use of CDK4/6 inhibitors in this pathology, alone or in combination with other drugs. This review, coupling basic, preclinical and clinical research studies, could be of great translational value for investigators attempting to design new clinical trials for the better management of ovarian cancer patients.

Abstract

Alterations in components of the cell-cycle machinery are present in essentially all tumor types. In particular, molecular alterations resulting in dysregulation of the G1 to S phase transition have been observed in almost all human tumors, including ovarian cancer. These alterations have been identified as potential therapeutic targets in several cancer types, thereby stimulating the development of small molecule inhibitors of the cyclin dependent kinases. Among these, CDK4 and CDK6 inhibitors confirmed in clinical trials that CDKs might indeed represent valid therapeutic targets in, at least some, types of cancer. CDK4 and CDK6 inhibitors are now used in clinic for the treatment of patients with estrogen receptor positive metastatic breast cancer and their clinical use is being tested in many other cancer types, alone or in combination with other agents. Here, we review the role of CDK4 and CDK6 complexes in ovarian cancer and propose the possible use of their inhibitors in the treatment of ovarian cancer patients with different types and stages of disease.

High Expression of miR-196b Predicts Poor Prognosis in Patients with Ovarian Cancer

Background/Aims

To analyze the clinical significance of miR-196b expression in ovarian cancer and predict the function and possible mechanism of miR-196b.

Methods

Both Kaplan–Meier (K-M) and Cox proportional hazards regression model were used to analyze the prognostic factors of patients with ovarian cancer. MiR196-b was modulated in ovarian cancer cells, and the cell viability, cell cycle, and cell cycle-related gene expression were analyzed. The target genes of miR-196b were then predicted and checked the relationship between the target genes.

Results

MiR-196b was an independent risk factor, while high expression of miR-196b was associated with poor prognosis of ovarian cancer. MiR-196b overexpression increased cancer cell proliferation. Cdkn1b, as one of the targets of miR-196b, was related to cell viability and mitosis.

Conclusion

High expression of miR-196b was significantly associated with poor prognosis of the patients with ovarian cancer. MiR-196b could increase the cell proliferation of ovarian cancer by modulating Cdkn1b expression.

Schizandrin A inhibits cellular phenotypes of breast cancer cells by repressing miR-155

AIMS

Schizandrin A (SchA) is a type of lignan with biological properties against oxidation, inflammation, and cancer. Here, we aimed to sustain the bioactive properties of SchA in proliferative and motional phenotypes of MDA-MB-231 cells and their molecular mechanism.

METHODS

MDA-MB-231 cells were exposed to SchA. At 24 h after SchA treatment, the viability and proliferation were measured using CCK-8 and BrdU incorporation methods, respectively. Propidium iodide/Annexin V-FITC staining was carried out for detecting apoptotic cells. Migration and invasion were detected by 24-Transwell assay. Proteins expression was evaluated by Western blotting. MDA-MB-231 cells were transfected with microRNA (miR)-155 mimic, and miR-155 was detected by qRT-PCR.

RESULTS

SchA weakens the viability of MDA-MB-231 cells in a dose-relative way (0-40 μM). Furthermore, 30 μM SchA significantly suppresses proliferation, enhances apoptosis, and inhibits migration and invasion. SchA strikingly decreases miR-155. Exogenous miR-155 counteracts the inhibitory effects that SchA confers on proliferative and motional activities. Finally, SchA was observed to blunt PI3K/AKT and Wnt/β-catenin while miR-155 mimic reverses the effects.

CONCLUSION

Taken together, SchA downregulates miR-155 and results in the suppression of proliferation and motility in breast cancer cells. Our findings proposed that SchA might be used as an underlying therapeutic agent.

NF90 stabilizes cyclin E1 mRNA through phosphorylation of NF90-Ser382 by CDK2

Nuclear factor 90 (NF90), an RNA-binding protein, has been implicated in regulating interleukin-2 (IL-2) and the immune response. It was recently reported that NF90 is upregulated in hepatocellular carcinoma (HCC) tissues and promotes HCC proliferation through upregulating cyclin E1 at the posttranscription level. However, the regulation of NF90 in HCC remains unclear. We demonstrate here that cyclin-dependent kinase (CDK) 2 interacts with NF90 and phosphorylated it at serine382. Mechanistically, phosphorylation of NF90-Ser382 determines the nuclear export of NF90 and stabilization of cyclin E1 mRNA. We also demonstrate that the phosphorylation deficient mutant NF90-S382A inhibits cell growth and induces cell cycle arrest at the G1 phase in HCC cells. Moreover, an NF90-S382A xenograft tumor had a decreased size and weight compared with the wildtype NF90. The NF90-S382A xenograft contained a significantly lower level of the proliferation marker Ki-67. Additionally, in HCC patients, NF90-Ser382 phosphorylation was stronger in tumor than in non-tumor tissues. Clinically, phosphorylation of NF90-Ser382 is significantly associated with larger tumor sizes, higher AFP levels, and shorter overall survival rates. These results suggest NF90-Ser382 phosphorylation serves as a potential diagnosis and prognostic marker and a promising pharmacological target for HCC.

The antipsychotic agent trifluoperazine hydrochloride suppresses triple-negative breast cancer tumor growth and brain metastasis by inducing G0/G1 arrest and apoptosis

Women with aggressive triple-negative breast cancer (TNBC) are at high risk of brain metastasis, which has no effective therapeutic option partially due to the poor penetration of drugs across the blood-brain barrier. Trifluoperazine (TFP) is an approved antipsychotic drug with good bioavailability in brain and had shown anticancer effect in several types of cancer. It drives us to investigate its activities to suppress TNBC, especially the brain metastasis. In this study, we chose three TNBC cell lines MDA-MB-468, MDA-MB-231, and 4T1 to assess its anticancer activities along with the possible mechanisms. In vitro, it induced G0/G1 cell cycle arrest via decreasing the expression of both cyclinD1/CDK4 and cyclinE/CDK2, and stimulated mitochondria-mediated apoptosis. In vivo, TFP suppressed the growth of subcutaneous xenograft tumor and brain metastasis without causing detectable side effects. Importantly, it prolonged the survival of mice bearing brain metastasis. Immunohistochemical analysis of Ki67 and cleaved caspase-3 indicated TFP could suppress the growth and induce apoptosis of cancer cells in vivo. Taken together, TFP might be a potential available drug for treating TNBC with brain metastasis, which urgently needs novel treatment options.

Antineoplastic Effects of Honokiol on Melanoma

Honokiol, a plant lignan has been shown to have antineoplastic effects against nonmelanoma skin cancer developments in mice. In this study, antineoplastic effects of honokiol were investigated in malignant melanoma models. In vitro effects of honokiol treatment on SKMEL-2 and UACC-62 melanoma cells were evaluated by measuring the cell viability, proliferation, apoptosis, cell cycle analysis, and expressions of various proteins associated with cell cycle progression and apoptosis. For the in vivo study, male nude mice inoculated with SKMEL-2 or UACC-62 cells received injections of sesame oil or honokiol for two to seven weeks. In vitro honokiol treatment caused significant decrease in cell viability, proliferation, cell cycle arrest, increased apoptosis, and modulation of apoptotic and cell cycle regulatory proteins. Honokiol caused an accumulation of cells in the G2/M phase of the cell cycle in SKMEL-2 and G0/G1 phase in UACC-62 cells. An elevated level of caspases and PARP were observed in both cell lines treated with honokiol. A decrease in the expression of various cell cycle regulatory proteins was also observed in honokiol treated cells. Honokiol caused a significant reduction of tumor growth in SKMEL-2 and UACC-62 melanoma xenografts. These findings suggest that honokiol is a good candidate for further studies as a possible treatment for malignant melanoma.

Dual CCNE1/PIK3CA targeting is synergistic in CCNE1-amplified/PIK3CA-mutated uterine serous carcinomas in vitro and in vivo

Background:

Clinical options for patients harbouring advanced/recurrent uterine serous carcinoma (USC), an aggressive variant of endometrial tumour, are very limited. Next-generation sequencing (NGS) data recently demonstrated that cyclin E1 (CCNE1) gene amplification and pik3ca driver mutations are common in USC and may therefore represent ideal therapeutic targets.

Methods:

Cyclin E1 expression was evaluated by immunohistochemistry (IHC) on 95 USCs. The efficacy of the cyclin-dependent kinase 2/9 inhibitor CYC065 was assessed on multiple primary USC cell lines with or without CCNE1 amplification. Cell-cycle analyses and knockdown experiments were performed to assess CYC065 targeting specificity. Finally, the in vitro and in vivo activity of CYC065, Taselisib (a PIK3CA inhibitor) and their combinations was tested on USC xenografts derived from CCNE1-amplified/pik3ca-mutated USCs.

Results:

We found that 89.5% of the USCs expressed CCNE1. CYC065 blocked cells in the G1 phase of the cell cycle and inhibited cell growth specifically in CCNE1-overexpressing USCs. Cyclin E1 knockdown conferred increased resistance to CYC065, whereas CYC065 treatment of xenografts derived from CCNE1-amplified USCs significantly reduced tumour growth. The combination of CYC065 and Taselisib demonstrated synergistic effect in vitro and was significantly more effective than single-agent treatment in decreasing tumour growth in xenografts of CCNE1-amplified/pik3ca-mutated USCs.

Conclusions:

Dual CCNE1/PIK3CA blockade may represent a novel therapeutic option for USC patients harbouring recurrent CCNE1-amplified/pi3kca-mutated tumours.

Cyclin-dependent kinase 2 is an ideal target for ovary tumors with elevated cyclin E1 expression

CCNE1 gene amplification is present in 15-20% ovary tumor specimens. Here, we showed that Cyclin E1 (CCNE1) was overexpressed in 30% of established ovarian cancer cell lines. We also showed that CCNE1 was stained positive in over 40% of primary ovary tumor specimens regardless of their histological types while CCNE1 staining was either negative or low in normal ovary and benign ovary tumor tissues. However, the status of CCNE1 overexpression was not associated with the tumorigenic potential of ovarian cancer cell lines and also did not correlate with pathological grades of ovary tumor specimens. Subsequent experiments with CCNE1 siRNAs showed that knockdown of CCNE1 reduced cell growth only in cells with inherent CCNE1 overexpression, indicating that these cells may have developed an addiction to CCNE1 for growth/survival. As CCNE1 is a regulatory factor of cyclin-dependent kinase 2 (Cdk2), we investigated the effect of Cdk2 inhibitor on ovary tumorigenecity. Ovarian cancer cells with elevated CCNE1 expression were 40 times more sensitive to Cdk2 inhibitorSNS-032 than those without inherent CCNE1 overexpression. Moreover, SNS-032 greatly prolonged the survival of mice bearing ovary tumors with inherent CCNE1 overexpression. This study suggests that ovary tumors with elevated CCNE1 expression may be staged for Cdk2-targeted therapy.

RNA interference of Biot2 induces G1 phase arrest and apoptosis in mouse colorectal cancer cell line

Biot2 is a tumor-associated antigen, and it is a novel gene (GenBank EF100607) that was first identified with the SEREX technique and named by our laboratory. It is highly expressed in cancer cells and testis, with low or no expression in normal tissues. In our previous study, RNA interference of human Biot2 can inhibit tumor cell growth, and it is associated with poor prognosis of patients in clinical study; however, the mechanism of Biot2 that effects tumor growth is not yet clear. Here, in this study, we explore further the mechanism of Biot2 by silencing Biot2 in CT26 cells. It provides some theoretical basis for Biot2 as a new target for gene therapy. In CT26 cells, the expression of Biot2 was downregulated by Biot2-shRNA. It also promoted G₁ phase arrest, the expression of p16 and p21, and cell apoptosis. In the mouse model, the tumor volume and the expression of PCNA of the Biot2-shRNA group significantly decreased. These results suggest that silencing Biot2 in CT26 cells by RNA interference can inhibit cell growth in vitro and in vivo. It also induces cell cycle arrest in the G₁ phase and apoptosis throughout regulation of p16 and p21. Taken together, our data demonstrate that Biot2 can be a potential target of gene therapy.

Regulation of cell cycle of hepatocellular carcinoma by NF90 through modulation of cyclin E1 mRNA stability

Activation of cyclin E1, a key regulator of the G1/S cell-cycle transition, has been implicated in many cancers including hepatocellular carcinoma (HCC). Although much is known about the regulation of cyclin E1 expression and stability, its post-transcriptional regulation mechanism remains incompletely understood. Here, we report that nuclear factor 90 (NF90), a double-stranded RNA (dsRNA) binding protein, regulates cyclin E1 in HCC. We demonstrate that NF90 is upregulated in HCC specimens and that suppression of NF90 decreases HCC cell growth and delays G1/S transition. We identified cyclin E1 as a new target of NF90 and found a significant correlation between NF90 and cyclin E1 expression in HCC. The mRNA and protein levels of cyclin E1 were downregulated upon NF90 knockdown. Suppression of NF90 caused a decrease in the half-life of cyclin E1 mRNA, which was rescued by ectopic expression of NF90. Furthermore, NF90 bound to the 3' untranslated regions (3'UTRs) of cyclin E1 mRNA in vitro and in vivo. Knockdown of NF90 also inhibited tumor growth of HCC cell lines in mouse xenograft model. Moreover, we showed that inhibition of NF90 sensitized HCC cells to the cyclin-dependent kinase 2 (CDK2) inhibitor, roscovitine. Taken together, downregulation of NF90 in HCC cell lines can delay cell-cycle progression, inhibit cell proliferation, and reduce tumorigenic capacity in vivo. These results suggest that NF90 has an important role in HCC pathogenesis and that it can serve as a novel therapeutic target for HCC.

Antiprogestins in gynecological diseases

Antiprogestins constitute a group of compounds, developed since the early 1980s, that bind progesterone receptors with different affinities. The first clinical uses for antiprogestins were in reproductive medicine, e.g., menstrual regulation, emergency contraception, and termination of early pregnancies. These initial applications, however, belied the capacity for these compounds to interfere with cell growth. Within the context of gynecological diseases, antiprogestins can block the growth of and kill gynecological-related cancer cells, such as those originating in the breast, ovary, endometrium, and cervix. They can also interrupt the excessive growth of cells giving rise to benign gynecological diseases such as endometriosis and leiomyomata (uterine fibroids). In this article, we present a review of the literature providing support for the antigrowth activity that antiprogestins impose on cells in various gynecological diseases. We also provide a summary of the cellular and molecular mechanisms reported for these compounds that lead to cell growth inhibition and death. The preclinical knowledge gained during the past few years provides robust evidence to encourage the use of antiprogestins in order to alleviate the burden of gynecological diseases, either as monotherapies or as adjuvants of other therapies with the perspective of allowing for long-term treatments with tolerable side effects. The key to the clinical success of antiprogestins in this field probably lies in selecting those patients who will benefit from this therapy. This can be achieved by defining the genetic makeup required - within each particular gynecological disease - for attaining an objective response to antiprogestin-driven growth inhibition therapy.Free Spanish abstractA Spanish translation of this abstract is freely available at http://www.reproduction-online.org/content/149/1/15/suppl/DC1.

Distinct expression pattern and post-transcriptional regulation of cell cycle genes in the glandular epithelia of avian ovarian carcinomas

The cell cycle system is controlled in a timely manner by three groups of cyclins, cyclin dependent kinases and cyclin dependent kinase inhibitors. Abnormal alterations of cell cycle regulatory mechanisms are a common feature of many diseases including numerous tumor types such as ovarian cancer. Although a variety of cell cycle regulatory genes are well known in mammalian species including human and mice, they are not well studied in avian species, especially in laying hens which are recognized as an excellent animal model for research relevant to human ovarian carcinogenesis. Therefore, in the present study, we focused on comparative expression and regulation of expression of candidate genes which might be involved in the cell cycle program in surface epithelial ovarian cancer in laying hens. Our current results indicate that expression levels of cell cycle gene transcripts are greater in cancerous as compared to normal ovaries. In particular, cyclin A2 (CCNA2), CCND1, CCND2, CCND3, CCNE2, cyclin dependent kinase 1 (CDK1), CDK3, CDK5, cyclin dependent kinases inhibitor 1A (CDKN1A) and CDKN1B were upregulated predominantly in the glandular epithelia of cancerous ovaries from laying hens. Further, several microRNAs (miRs), specifically miR-1798, miR-1699, miR-223 and miR-1744 were discovered to influence expression of CCND1, CCNE2, CDK1, and CDK3 mRNAs, respectively, via their 3′-UTR which suggests that post-transcriptional regulation of gene expression influences their expression in laying hens. Moreover, miR-1626 influenced CDKN1A expression and miR-222, miR-1787 and miR-1812 regulated CDKN1B expression via their 3′-UTR regions. Collectively, results of the present study demonstrate increased expression of cell cycle-related genes in cancerous ovaries of laying hens and indicate that expression of these genes is post-transcriptionally regulated by specific microRNAs.

Prognostic biomarkers in ovarian cancer

Epithelial ovarian cancer (EOC) remains the most lethal gynecological malignancy despite several decades of progress in diagnosis and treatment. Taking advantage of the robust development of discovery and utility of prognostic biomarkers, clinicians and researchers are developing personalized and targeted treatment strategies. This review encompasses recently discovered biomarkers of ovarian cancer, the utility of published prognostic biomarkers for EOC (especially biomarkers related to angiogenesis and key signaling pathways), and their integration into clinical practice.

Altered expression of p27(Kip1) -interacting cell-cycle regulators in the adult testicular germ cell tumors: potential role in tumor development and histological progression

We examined the potential role of cell-cycle dysregulation in the development and histological progression of adult testicular germ cell tumors (TGCTs). Expressions of p27(Kip1) -interacting cell-cycle regulators (down-regulation of p27(Kip1) and overexpression of Skp2, Cks1, cyclin A, and cyclin E) and Ki-67 labeling index (LI) were immunohistochemically examined in histological components of 50 intratubular germ cell neoplasms, unclassified (IGCNUs); 74 seminomas; and 25 embryonal carcinomas, identified from 88 patients. Altered expression of p27(Kip1) , Skp2, Cks1, cyclin A, and cyclin E was observed in 20%, 12%, 16%, 10%, and 24% of IGCNUs; 26%, 36%, 27%, 89%, and 23% of seminomas; and 48%, 68%, 56%, 100%, and 60% of embryonal carcinomas, respectively. A significant difference in the frequency of Skp2 and cyclin A overexpression was observed between IGCNUs and seminomas. Significantly more frequent alterations of Skp2, Cks1, and cyclin E and p27(Kip1) were detected in embryonal carcinomas than in seminomas. Alterations of all cell-cycle regulators were significantly more frequent in embryonal carcinomas than in IGCNUs. The mean Ki-67 LI significantly increased from IGCNU (21.2%) through seminoma (34.7%) to embryonal carcinoma (54.2%). These results suggest that alterations of the p27(Kip1) -interacting cell-cycle regulators are common in TGCTs and may be involved in their histological progression.

Limited prognostic value of tissue protein expression levels of cyclin E in Danish ovarian cancer patients: from the Danish 'MALOVA' ovarian cancer study

The primary objective of this study was to assess the expression of cyclin E in tumour tissues from 661 patients with epithelial ovarian tumours. The second was to evaluate whether cyclin E tissue expression levels correlate with clinico-pathological parameters and prognosis of the disease. Using tissue arrays (TA), we analysed the cyclin E expression levels in tissues from 168 women with borderline ovarian tumours (BOT) (147 stage I, 4 stage II, 17 stage III) and 493 Ovarian cancer (OC) patients (127 stage I, 45 stage II, 276 stage III, 45 stage IV). Using a 10% cut-off level for cyclin E overexpression, 20% of the BOTs were positive with a higher proportion of serous than mucinous tumours. Sixty-two per cent of the OCs were positive for cyclin E expression with the highest percentage found in clear cell carcinomas. Results based on univariate and multivariate survival analyses with a 10% cut-off value showed that cyclin E had no independent prognostic value. In conclusion, we found cyclin E expression in tumour tissue to be of limited prognostic value to Danish OC patients.

Implementing an online tool for genome-wide validation of survival-associated biomarkers in ovarian-cancer using microarray data from 1287 patients

The validation of prognostic biomarkers in large independent patient cohorts is a major bottleneck in ovarian cancer research. We implemented an online tool to assess the prognostic value of the expression levels of all microarray-quantified genes in ovarian cancer patients. First, a database was set up using gene expression data and survival information of 1287 ovarian cancer patients downloaded from Gene Expression Omnibus and The Cancer Genome Atlas (Affymetrix HG-U133A, HG-U133A 2.0, and HG-U133 Plus 2.0 microarrays). After quality control and normalization, only probes present on all three Affymetrix platforms were retained (n=22,277). To analyze the prognostic value of the selected gene, we divided the patients into two groups according to various quantile expressions of the gene. These groups were then compared using progression-free survival (n=1090) or overall survival (n=1287). A Kaplan-Meier survival plot was generated and significance was computed. The tool can be accessed online at www.kmplot.com/ovar. We used this integrative data analysis tool to validate the prognostic power of 37 biomarkers identified in the literature. Of these, CA125 (MUC16; P=3.7×10(-5), hazard ratio (HR)=1.4), CDKN1B (P=5.4×10(-5), HR=1.4), KLK6 (P=0.002, HR=0.79), IFNG (P=0.004, HR=0.81), P16 (P=0.02, HR=0.66), and BIRC5 (P=0.00017, HR=0.75) were associated with survival. The combination of several probe sets can further increase prediction efficiency. In summary, we developed a global online biomarker validation platform that mines all available microarray data to assess the prognostic power of 22,277 genes in 1287 ovarian cancer patients. We specifically used this tool to evaluate the effect of 37 previously published biomarkers on ovarian cancer prognosis.

Cyclin E low-molecular-weight isoform as a predictor of breast cancer in Japanese women

Overexpression of low-molecular-weight isoforms (LMWI) of cyclin E in breast cancer cells is associated with poor prognosis and could serve a novel role in breast cancer progression. LMWI originate from proteolytic processing of cyclin E, which is deregulated and hyperactive. In this study, levels of full-form/LMWI cyclin E were determined with the use of Western blot analysis in 69 Japanese breast cancer patients. LMWI cyclin E levels were significantly correlated with known parameters such as tumor grade and estrogen/progesterone receptor expression. In multivariate analysis, patient survival was significantly correlated with tumor grade but not with either form of cyclin E. LMWI was not as strong a predictor as tumor grade in this study, whereas some cases of early relapse with LMWI overexpression and lower tumor grade were reported. Thus, LMWI might be a good complementary factor to other predictors for early relapse of breast cancer.

Growth inhibition induced by antiprogestins RU-38486, ORG-31710, and CDB-2914 in ovarian cancer cells involves inhibition of cyclin dependent kinase 2

Antiprogestins have been largely utilized in reproductive medicine, yet their repositioning for oncologic use is rapidly emerging. In this study we investigated the molecular mediators of the anti-ovarian cancer activity of the structurally related antiprogestins RU-38486, ORG-31710 and CDB-2914. We studied the responses of wt p53 OV2008 and p53 null SK-OV-3 cells to varying doses of RU-38486, ORG-31710 and CDB-2914. The steroids inhibited the growth of both cell lines with a potency of RU-38486 > ORG-31710 > CDB-2914, and were cytostatic at lower doses but lethal at higher concentrations. Antiprogestin-induced lethality associated with morphological features of apoptosis, hypodiploid DNA content, DNA fragmentation, and cleavage of executer caspase substrate PARP. Cell death ensued despite RU-38486 caused transient up-regulation of anti-apoptotic Bcl-2, ORG-31710 induced transient up-regulation of inhibitor of apoptosis XIAP, and CDB-2914 up-regulated both XIAP and Bcl-2. The antiprogestins induced accumulation of Cdk inhibitors p21^cip1 and p27^kip1 and increased association of p21^cip1 and p27^kip1 with Cdk-2. They also promoted nuclear localization of p21^cip1 and p27^kip1, reduced the nuclear abundances of Cdk-2 and cyclin E, and blocked the activity of Cdk-2 in both nucleus and cytoplasm. The cytotoxic potency of the antiprogestins correlated with the magnitude of the inhibition of Cdk-2 activity, ranging from G1 cell cycle arrest towards cell death. Our results suggest that, as a consequence of their cytostatic and lethal effects, antiprogestin steroids of well-known contraceptive properties emerge as attractive new agents to be repositioned for ovarian cancer therapeutics.

Nuclear P27 expression in benign, borderline (LMP) and invasive tumors of the ovary and its association with prognosis: a gynecologic oncology group study

OBJECTIVE

Nuclear p27 expression was examined in non-invasive and invasive ovarian tumors from a cross-sectional study, and clinical relevance of p27 was evaluated in the primary tumors from women participating in two randomized phase III treatment trials.

METHODS

An immunohistochemistry assay was used to detect p27 in formalin-fixed paraffin-embedded ovarian tumors from 3 distinct sources.

RESULTS

Among the initial 91 ovarian tumors tested, low p27 expression (<50% positive cells) was observed in 5.4% of non-invasive tumors versus 42.6% of invasive tumors (p<0.001). In 145 ovarian cancers with high-risk early stage disease, 16.5% exhibited low p27 expression, and categorized p27 was not associated with age, race, or performance status. Low expression of p27 was common in poorly differentiated tumors (35.7%) compared to moderately (15.0%) and well (9.5%) differentiated tumors (p=0.024) and rare in clear cell carcinomas (2.4%) compared to other histologies (p=0.014). In the 139 cancers with advanced disease, 60% displayed low p27 expression, and categorized p27 expression was not associated with age, race, performance status, tumor grade, histologic subtype, measurable disease status or survival. Exploratory analyses revealed an association of cyclin E to p27 ratio >1.0 with an increased risk of death (hazard ratio=1.53; p=0.017).

CONCLUSIONS

Low p27 expression could be associated with malignant transformation of the ovarian epithelium and FIGO stage. A cyclin E to p27 ratio >1.0 may be associated with shorter survival in these patients. Further study is required to confirm the trend for increased recurrences with low p27 expression in early stage disease.

Microenvironment and pathogenesis of epithelial ovarian cancer

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

Cyclin-dependent kinase inhibitor p27 as a prognostic biomarker and potential cancer therapeutic target

The prognosis and clinical management of patients with cancer is commonly determined by traditional clinical and pathological factors. Nevertheless, patients may present with significantly different clinical outcomes despite similar clinicopathological features. This has prompted intense research to find biological markers that may closely reflect tumor biology and thereby clinical outcome. This article presents the current knowledge on the prognostic significance of p27 expression in cancer and its potential role as a target for future therapy.

p27: a barometer of signaling deregulation and potential predictor of response to targeted therapies

Phosphorylation of the cyclin-dependent kinase inhibitor p27 by upstream mitogenic signaling pathways regulates its stability, localization, and biological function. In human cancers, loss of the antiproliferative action of p27 can arise through reduced protein levels and/or cytoplasmic mislocalization, leading to increased cell proliferation and/or cell migration, respectively. Reduced p27 expression levels and p27 mislocalization have potential prognostic and therapeutic implications in various types of human cancers. This review highlights mechanisms of functional deregulation of p27 by oncogenic signaling that provide an important molecular rationale for pathway targeting in cancer treatment.

Predictive and prognostic protein biomarkers in epithelial ovarian cancer: recommendation for future studies

Epithelial ovarian cancer is the most lethal gynecological malignancy. Due to its lack of symptoms, this disease is diagnosed at an advanced stage when the cancer has already spread to secondary sites. While initial rates of response to first treatment is >80%, the overall survival rate of patients is extremely low, mainly due to development of drug resistance. To date, there are no reliable clinical factors that can properly stratify patients for suitable chemotherapy strategies. Clinical parameters such as disease stage, tumor grade and residual disease, although helpful in the management of patients after their initial surgery to establish the first line of treatment, are not efficient enough. Accordingly, reliable markers that are independent and complementary to clinical parameters are needed for a better management of these patients. For several years, efforts to identify prognostic factors have focused on molecular markers, with a large number having been investigated. This review aims to present a summary of the recent advances in the identification of molecular biomarkers in ovarian cancer patient tissues, as well as an overview of the need and importance of molecular markers for personalized medicine in ovarian cancer.

Cytoplasmic p27 expression is an independent prognostic factor in ovarian cancer

Dysregulation of the cell cycle is an important prerequisite for cancer development. p27 has an established role in cell cycle control and hence may be disrupted during carcinogenesis. The influence of p27 expression, including its subcellular location, on tumor behavior in ovarian cancer has been controversial. The purpose of this study was to evaluate the expression of p27 in a large population of patients with ovarian cancer and correlate this to clinicopathologic variables including overall survival. Using a tissue microarray of 339 primary ovarian cancers, the expression of p27 was assessed immunohistochemically. Coupled to a comprehensive database of clinicopathologic variables, its effect on these factors and survival was studied. Cytoplasmic p27 showed a progressively negative impact on overall survival (P=0.004). Tumors displaying nuclear p27 also had poorer prognosis (P=0.014). Factors shown to predict prognosis independently of each other were age, stage, and the absence of macroscopic disease after surgery. Cytoplasmic p27 expression, but not nuclear, was independently predictive of prognosis on multivariate analysis (P=0.042). Both subcellular locations of p27 expression were more frequently observed in serous compared with mucinous subtypes. Cytoplasmic p27 independently predicts poorer prognosis in ovarian carcinoma. These results seem counterintuitive, when considering the antiproliferative role of p27, but may reflect a more complex function of p27 within cell cycle regulation. These data support a novel role for p27 within the cytoplasm, possibly through effects on apoptosis, cellular motility, and drug resistance.

Cold-inducible RNA-binding protein contributes to human antigen R and cyclin E1 deregulation in breast cancer

The cell cycle regulator cyclin E1 is aberrantly expressed in a variety of human cancers. In breast cancer, elevated cyclin E1 correlates with poor outcome, as do high cytoplasmic levels of the stress-induced RNA-binding protein human antigen R (HuR). We showed previously that increased cytoplasmic HuR elevates cyclin E1 in MCF-7 breast cancer cells by stabilizing its mRNA. We show here that cold-inducible RNA-binding protein (CIRP) co-regulates cyclin E1 with HuR in breast cancer cells. CIRP had been shown to interact with HuR in Xenopus laevis oocytes and to be decreased in endometrial cancer. To investigate if human CIRP and HuR co-regulate cyclin E1, HuR and CIRP levels were altered in MCF-7 cells and effects on cyclin E1 assessed. Altering HuR expression resulted in a reciprocal change in CIRP expression, while altering CIRP expression resulted in corresponding changes in HuR and cyclin E1 expression. CIRP and HuR co-precipitated in the presence of RNA and CIRP enhanced HuR binding to the cyclin E1 mRNA and increased cyclin E1 mRNA stability. CIRP co-localized with HuR predominantly in the nucleus, but also in discrete cytoplasmic foci identified as stress granules (SGs). CIRP overexpression increased the number of HuR-containing SGs, while its knockdown decreased them. Our results suggest that CIRP positively regulates HuR, ultimately resulting in increased protein synthesis of at least one of its targets.

Low molecular weight cyclin E is specific in breast cancer and is associated with mechanisms of tumor progression

Low molecular weight (LMW) isoforms of cyclin E are post-translationally generated in breast cancer cells and are associated with aggressive disease and poor prognosis. In this study, the specificity of LMW cyclin E to cancer cells was determined by measuring cyclin E expression in tumor and non-tumor tissue from 340 breast cancer patients. Our results reveal the LMW isoforms were detected significantly more frequently in breast tumor tissue than in adjacent non-tumor breast tissues (p < 0.0001). The biologic consequences of the LMW isoforms were studied using a non-tumorigenic mammary epithelial cell line transfected with the cyclin E isoforms and resulted in increased clonogenicity, the inability to enter quiescence in response to growth factor deprivation and genomic instability compared to the full-length cyclin E. Biochemical differences between the full-length and the LMW isoforms were also evident. Biacore analyses show that the LMW isoforms have more efficient binding to CDK2 compared to full-length cyclin E, which could account for the unique biologic consequences observed with the expression of LMW cyclin E. The LMW isoforms of cyclin E are tumor specific, and are biochemically and biologically distinct from the full-length cyclin E which could provide a novel role in breast cancer progression.

Analysis of gene expression in early-stage ovarian cancer

PURPOSE

Gene expression profile was analyzed in 68 stage I and 15 borderline ovarian cancers to determine if different clinical features of stage I ovarian cancer such as histotype, grade, and survival are related to differential gene expression.

EXPERIMENTAL DESIGN

Tumors were obtained directly at surgery and immediately frozen in liquid nitrogen until analysis. Glass arrays containing 16,000 genes were used in a dual-color assay labeling protocol.

RESULTS

Unsupervised analysis identified eight major patient partitions, one of which was statistically associated to overall survival, grading, and histotype and another with grading and histotype. Supervised analysis allowed detection of gene profiles clearly associated to histotype or to degree of differentiation. No difference was found between borderline and grade 1 tumors. As to recurrence, a subset of genes able to differentiate relapsers from nonrelapsers was identified. Among these, cyclin E and minichromosome maintenance protein 5 were found particularly relevant, as their expression was inversely correlated to progression-free survival (P = 0.00033 and 0.017, respectively).

CONCLUSIONS

Specific molecular signatures define different histotypes and prognosis of stage I ovarian cancer. Mucinous and clear cells histotypes can be distinguished from the others regardless of tumor grade. Cyclin E and minichromosome maintenance protein 5, whose expression was found previously to be related to a bad prognosis of advanced ovarian cancer, appear to be potential prognostic markers in stage I ovarian cancer too, independent of other pathologic and clinical variables.

Loss of nuclear p27 expression and its prognostic role in relation to cyclin E and p53 mutation in gastroenteropancreatic neuroendocrine tumors

PURPOSE

Gastroenteropancreatic neuroendocrine tumors (GEP-NET) are classified by the WHO, yet its prognostic value needs to be confirmed. Therefore, we aimed to determine the prognostic role of cell cycle key regulatory genes p53, p27kip1 (p27), and cyclin E in this tumor entity.

EXPERIMENTAL DESIGN

Tumor specimen from 89 patients with a complete follow-up were studied immunohistochemically for p27 and cyclin E expression and for p53 mutations. The functional relevance of p27 was evaluated in the neuroendocrine cell lines BON1 (human) and INS1 (rat) by the use of small interfering RNA.

RESULTS

Twenty-six of 29 benign, well-differentiated endocrine tumors (WHO class 1) showed a high expression (> 50%) of p27, whereas all 10 poorly differentiated endocrine carcinomas (WHO class 3) displayed a low expression of p27. Metastatic well-differentiated endocrine carcinomas (WHO class 2) showed a low p27 expression in 20 of 50 (40%) patients, which conferred a poor prognosis (median survival, 57 versus 140 months; P = 0.037). This prognostic dichotomy was improved by the use of a combination of p27 and cyclin E (high cyclin E/low p27 versus low cyclin E/high p27: median survival 53 months versus not reached; P = 0.0044). p53 mutations were rare (1 of 10 poorly differentiated endocrine carcinomas).

CONCLUSIONS

Loss of p27 and overexpression of cyclin E play a critical role in the aggressiveness of gastroenteropancreatic neuroendocrine tumors. This coincides with increased cell cycle progression. We propose a discussion whether to incorporate the immunohistochemical expression of p27 into a revised classification to individualize therapeutic strategies in this tumor entity.

Serum and tissue biomarkers as predictive and prognostic variables in epithelial ovarian cancer

Tumour stage, residual disease after initial surgery, histological type and tumour grade are the most important clinical-pathological factors related to the clinical outcome of patients with epithelial ovarian cancer. In the last years, several investigations have assessed different biological variables in sera and in tissue samples from patients with this malignancy in order to detect biomarkers able to reflect either the response to chemotherapy or survival. The present paper reviewed the literature data about the predictive or prognostic relevance of serum CA 125, soluble cytokeratin fragments, serum human kallikreins, serum cytokines, serum vascular endothelial growth factor and plasma d-dimer as well as of tissue expression of cell cycle- and apoptosis-regulatory proteins, human telomerase reverse transcriptase, membrane tyrosine kinase receptors and matrix metalloproteinases. A next future microarray technology will hopefully offer interesting perspectives of translational research for the identification of novel predictive and prognostic biomarkers for epithelial ovarian cancer.

The Cdk inhibitor p27 in human cancer: prognostic potential and relevance to anticancer therapy

The cyclin-dependent kinase (Cdk) inhibitor p27 (also known as KIP1) regulates cell proliferation, cell motility and apoptosis. Interestingly, the protein can exert both positive and negative functions on these processes. Diverse post-translational modifications determine the physiological role of p27. Phosphorylation regulates p27 binding to and inhibition of cyclin-Cdk complexes, its localization and its ubiquitin-mediated proteolysis. In cancers, p27 is inactivated through impaired synthesis, accelerated degradation and by mislocalization. Moreover, studies in several tumour types indicate that p27 expression levels have both prognostic and therapeutic implications.

Identification of breast cancer peptide epitopes presented by HLA-A*0201

Cellular immune mechanisms detect and destroy cancerous and infected cells via the human leukocyte antigen (HLA) class I molecules that present peptides of intracellular origin on the surface of all nucleated cells. The identification of novel, tumor-specific epitopes is a critical step in the development of immunotherapeutics for breast cancer. To directly identify peptide epitopes unique to cancerous cells, secreted human class I HLA molecules (sHLA) were constructed by deletion of the transmembrane and cytoplasmic domain of HLA A*0201. The resulting sHLA-A*0201 was transferred and expressed in breast cancer cell lines MCF-7, MDA-MB-231, and BT-20 as well as in the immortal, nontumorigenic cell line MCF10A. Stable transfectants were seeded into bioreactors for production of > 25 mg of sHLA-A*0201. Peptides eluted from affinity purified sHLA were analyzed by mass spectroscopy. Comparative analysis of HLA-A*0201 peptides revealed 5 previously uncharacterized epitopes uniquely presented on breast cancer cells. These peptides were derived from intracellular proteins with either well-defined or putative roles in breast cancer development and progression: Cyclin Dependent Kinase 2 (Cdk2), Ornithine Decarboxylase (ODC1), Kinetochore Associated 2 (KNTC2 or HEC1), Macrophage Migration Inhibitory Factor (MIF), and Exosome Component 6 (EXOSC6). Cellular recognition of the MIF, KNTC2, EXOSC6, and Cdk2 peptides by circulating CD8+ cells was demonstrated by tetramer staining and IFN-gamma ELISPOT. The identification and characterization of peptides unique to the class I of breast cancer cells provide putative targets for the development of immune diagnostic tools and therapeutics.

Early Events in the Pathogenesis of Epithelial Ovarian Cancer

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

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.

Expression and prognostic significance of cyclin D3 in ovarian adenocarcinomas

Abnormal expression of cell cycle regulators may contribute to malignant transformation. However, the clinical significance of the expression of cyclin D3 in ovarian cancer remains undefined. We therefore conducted a retrospective investigation to address the role of this cell-cycle protein in this tumor. In our study, paraffin-embedded tissue from 109 nonbenign epithelial ovarian tumors, including 17 tumors of low malignant potential and 92 primary adenocarcinomas, was stained immunohistochemically for cyclin D3. Most of the cases had previously been stained for pRb, p21Cip1, p27Kip1, p53, and Ki-67 antigen. Expression of cyclin D3 was correlated with clinicopathologic features, the expression of other cell cycle regulators, and postoperative survival of patients. Cyclin D3 levels were significantly higher in tumors of low malignant potential than in adenocarcinomas (P = 0.0002). In the latter group, cyclin D3 expression decreased with increasing grade (P = 0.0004) and advancing stage (P = 0.0315). Cyclin D3 expression positively correlated with pRb, p21Cip1, and p27Kip1 levels (P = 0.0021; P = 0.0036; P < 0.0001, respectively) and negatively with p53 and Ki-67 (P = 0.0003; P < 0.0001). Absent cyclin D3 expression was an important indicator of poor survival in univariate analysis in the entire cohort (P > 0.00010) and in the platinum-treated patients (P = 0.001) and in multivariate analysis (P = 0.044). Our results demonstrate that absent or decreased cyclin D3 expression is adversely related to several clinicopathologic indicators of aggressiveness in ovarian adenocarcinomas and is combined with a better prognosis, suggesting that cyclin D3 may have a biological role distinct from that of other G1 cyclins which is possibly regulated through interaction with other cell cycle genes.

HuR contributes to cyclin E1 deregulation in MCF-7 breast cancer cells

Many cancers overexpress cyclin E1 and its tumor-specific low molecular weight (LMW) isoforms. However, the mechanism of cyclin E1 deregulation in cancers is still not well understood. We show here that the mRNA-binding protein HuR increases cyclin E1 mRNA stability in MCF-7 breast carcinoma cells. Thus, mRNA stabilization may be a key event in the deregulation of cyclin E1 in MCF-7 cells. Compared with MCF10A immortalized breast epithelial cells, MCF-7 cells overexpress full-length cyclin E1 and its LMW isoforms and exhibit increased cyclin E1 mRNA stability. Increased mRNA stability is associated with a stable adenylation state and an increased ratio of cytoplasmic versus nuclear HuR. UV cross-link competition and UV cross-link immunoprecipitation assays verified that HuR specifically bound to the cyclin E1 3'-untranslated region. Knockdown of HuR with small interfering RNA (siRNA) in MCF-7 cells decreased cyclin E1 mRNA half-life (t(1/2)) and its protein level: a 22% decrease for the full-length isoforms and 80% decrease for the LMW isoforms. HuR siRNA also delayed G(1)-S phase transition and inhibited MCF-7 cell proliferation, which was partially recovered by overexpression of a LMW isoform of cyclin E1. Overexpression of HuR in MCF10A cells increased cyclin E1 mRNA t(1/2) and its protein level. Taken together, our data show that HuR critically contributes to cyclin E1 overexpression and its growth-promoting function, at least in part by increasing cyclin E1 mRNA stability, which provides a new mechanism of cyclin E1 deregulation in breast cancer.

Low-molecular weight forms of cyclin E differentiate ovarian carcinoma from cells of mesothelial origin and are associated with poor survival in ovarian carcinoma

BACKGROUND

The authors recently reported on the role of cyclin E in differentiating ovarian/primary peritoneal carcinoma from malignant peritoneal mesothelioma using gene expression arrays. In the current study, they analyzed the expression of low-molecular weight (LMW) forms of cyclin E in ovarian carcinoma, malignant mesothelioma, and benign reactive effusions.

METHODS

Cyclin E protein expression was analyzed in 98 effusions (72 ovarian carcinomas, 14 malignant mesotheliomas, and 12 reactive specimens) using immunoblotting. Sixty-two ovarian carcinoma effusions were studied further for cyclin E expression using immunohistochemistry. The correlations between cyclin E expression in ovarian carcinoma and clinical parameters, including chemotherapy response, were analyzed.

RESULTS

LMW forms of cyclin E were identified in 54 of 72 ovarian carcinoma effusions (75%) compared with 1 of 14 malignant mesothelioma effusions (7%) and 1 of 12 reactive effusions (8%) (P < .001). Their presence in ovarian carcinoma was associated with a higher percentage of cyclin E-positive cells (P = .001) and increased staining intensity (P < .001) using immunohistochemistry. The presence of LMW forms of cyclin E was correlated with shorter overall survival (P = .021) and progression-free survival (P = .020). The presence of a higher percentage of cyclin E-positive cells using immunohistochemistry was correlated with shorter progression-free survival (P = .026). No association with chemotherapy response was observed.

CONCLUSIONS

LMW forms of cyclin E differentiated ovarian carcinoma from benign and malignant mesothelial cells and were associated with increased protein expression using immunohistochemistry. The expression of LMW cyclin E forms was not associated with chemotherapy response, although it may be a marker of aggressive disease in patients with metastatic ovarian carcinoma.

Cyclin E-associated kinase activity predicts response to platinum-based chemotherapy

PURPOSE

The role of cyclin E as a predictive marker of response to chemotherapy remains unknown. We have previously shown that deregulation of cyclin E in an ovarian tumor cell line model enhances cyclin E-associated kinase activity and sensitizes tumor cells to cisplatinum. We hypothesized that cyclin E deregulation would predict for responsiveness to platinum-based regimens in ovarian cancer patients.

EXPERIMENTAL DESIGN

Patients who met the following criteria were retrospectively identified from the institutional tumor bank records: (a) high-grade ovarian epithelial malignancy, (b) stage III/stage IV disease, (c) optimally debulked, (d) completed platinum-based therapy. Tumor samples were analyzed for cyclin E, p21, and p27 by Western blot analysis and assessed for cyclin E-associated kinase activity.

RESULTS

Seventy-five patients, who met the study criteria, were identified. Cyclin E protein levels did not correlate with cyclin E-cdk2 kinase activity (Spearman's rho, 0.07; P = 0.58). Cyclin E-associated kinase activity was the only significant predictive marker for response to platinum-based therapy, with higher response rates seen in patients with higher levels of activity (P = 0.045). Cyclin E protein levels did not predict for platinum sensitivity (P = 0.20). In contrast, cyclin E protein levels, but not cyclin E-associated kinase activity, was a significant predictor for freedom from recurrence (P = 0.01 and P = 0.25, respectively).

CONCLUSIONS

Cyclin E overexpression and cyclin E-associated kinase activity have distinct roles in predicting for response to chemotherapy and outcome in ovarian cancer patients. These results suggest a compartmentalization of cyclin E functions in the oncogenic process.

Mifepristone inhibits ovarian cancer cell growth in vitro and in vivo

PURPOSE

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

EXPERIMENTAL DESIGN

The effect of mifepristone on ovarian cancer cell growth in vitro was studied in ovarian cancer cell lines of different genetic backgrounds (SK-OV-3, Caov-3, OV2008, and IGROV-1). In addition, the growth inhibition capacity of mifepristone on ovarian carcinoma xenografts was tested in nude mice.

RESULTS

Mifepristone inhibited ovarian cancer cell proliferation in a dose- and time-dependent manner. The cytostatic effect of mifepristone was confirmed in a clonogenic survival assay and was not linked to loss of viability. Mifepristone blocked DNA synthesis, arrested the cell cycle at the G(1)-S transition, up-regulated cyclin-dependent kinase (cdk) inhibitors p21(cip1)and p27(kip1), down-regulated transcription factor E2F1, decreased expression of the E2F1-regulated genes cdk1 (cdc2) and cyclin A, and modestly decreased cdk2 and cyclin E levels. The abrupt arrest in cell growth induced by mifepristone correlated with reduced cdk2 activity, increased association of cdk2 with p21(cip1) and p27(kip1), increased nuclear localization of the cdk inhibitors, and reduced nuclear abundance of cdk2 and cyclin E. In vivo, mifepristone significantly delayed the growth of ovarian carcinoma xenografts in a dose-dependent manner and without apparent toxic effects for the animals.

CONCLUSIONS

These preclinical studies show that mifepristone is effective as a single agent in vitro and in vivo, inhibiting the growth of human epithelial ovarian cancer cells. Mifepristone markedly reduces cdk2 activity likely due to increased association of cdk2 with the cdk inhibitors p21(cip1) and p27(kip1) and reduced nuclear cdk2/cyclin E complex availability. Acting as a cytostatic agent, mifepristone promises to be of translational significance in ovarian cancer therapeutics.

Skp2 is an independent prognosticator of gallbladder carcinoma among p27(Kip1)-interacting cell cycle regulators: an immunohistochemical study of 62 cases by tissue microarray

Despite improvement in surgical techniques, prognosis of gallbladder carcinoma remains poor. It is desirable to identify prognostic biomarkers to aid in the development of targeted therapeutic strategies. Two SCF(Skp2) ubiquitin ligase-related proteins, Skp2 and cyclin-dependent kinase subunit 1 (Cks1), are involved in post-transcriptional degradation of p27(Kip1) tumor suppressor, which inhibits both cdk2/cyclin E and cdk2/cyclin A complexes and thus prevents transition to the S phase. However, the prognostic utility of p27(Kip1)-interacting cell cycle regulators has not been systematically assessed in gallbladder carcinoma. Immunohistochemistry was performed for p27(Kip1), Skp2, Cks1, cyclin E, cyclin A, and Ki-67 in tissue microarrays of 62 gallbladder carcinomas with follow-up. The data were correlated with clinicopathological features and overall survival (OS). The cumulative OS rate for all 62 cases was 42.9% at 3 years. Aberrant labeling indices (LIs) of p27(Kip1) (<20%), cyclin E (>or=5%), cyclin A (>or=5%), Cks1 (>or=40%), and Skp2 (>or=10%) were identified in 29, 58, 66, 21, and 57% of gallbladder carcinomas, respectively. By log-rank tests, downregulation of p27(Kip1) (P=0.0319) and high LIs of Skp2 (P=0.0006), Cks1 (P=0.0460), cyclin E (P=0.0070), and Ki-67 (P=0.0037) were predictive of inferior OS. Furthermore, the combined expression status of Skp2 and Ki-67 robustly defined three prognostically different groups (P=0.0001). In multivariate comparison, Skp2 overexpression represented the strongest independent adverse prognosticator (P=0.004, risk ratio (RR): 5.538), followed by Ki-67 LI >or=50% (P=0.016, RR: 3.254) and American Joint Committee on Cancer stages II-IV (P=0.013, RR: 3.163). In conclusion, aberrations of p27(Kip1)-interacting cell cycle regulators are common in gallbladder carcinomas. Skp2 overexpression is highly representative of biological aggressiveness and independently associated with poor OS, suggesting that it is a promising novel target for therapeutic intervention in aggressive cases. The combined assessment of Skp2 and Ki-67 LIs effectively risk-stratifies gallbladder carcinomas with different prognosis, which is worth being prospectively validated in future study.

Expression of the chromatin remodeling factor Rsf-1 is upregulated in ovarian carcinoma effusions and predicts poor survival

OBJECTIVE

We recently identified Rsf-1, a chromatin remodeling gene, as a potential oncogene that is frequently amplified and overexpressed in ovarian serous carcinoma. However, its clinical role in ovarian cancer effusions is not clear. In the present study, we assessed the clinical significance of Rsf-1 overexpression in ovarian carcinoma effusions.

METHODS

Formalin-fixed paraffin-embedded sections from 168 effusions (134 peritoneal, 34 pleural) were analyzed for Rsf-1 expression using immunocytochemistry. Matched primary tumors (n=48) and solid metastases (n=73) from 48 patients were additionally studied. Rsf-1 expression in tumor cells in effusions was analyzed for possible association with clinicopathologic parameters and survival.

RESULTS

Rsf-1 protein expression was found in carcinoma cells in 157/168 (93%) effusions. Of these, 70 (45%) stained weakly and 87 (55%) strongly. Specimens from patients diagnosed with FIGO stage IV disease had higher staining score (extent x intensity) compared with stage III tumors (P=0.008). Rsf-1 expression level was significantly lower in primary tumors and solid metastases (P<0.001 for extent, intensity and score). Univariate survival analysis for 59 patients with post-chemotherapy recurrence effusions demonstrated a significant association between higher Rsf-1 staining and shorter overall survival (OS; P=0.009 for staining extent and intensity, P=0.02 for staining score). FIGO stage was the only clinical parameter associated with OS in this group (P=0.032). In Cox analysis, Rsf-1 expression (P=0.022 for staining extent and intensity, P=0.045 for staining score) and FIGO stage (P=0.035) were independent predictors of shorter survival.

CONCLUSIONS

Rsf-1 is frequently expressed and upregulated in ovarian carcinoma cells in effusions and is a novel prognostic marker for patients with post-chemotherapy recurrent disease. The above findings support a role of Rsf-1 in mediating disease progression and aggressive clinical behavior in this subset of ovarian carcinoma patients.

Gene expression signatures differentiate ovarian/peritoneal serous carcinoma from diffuse malignant peritoneal mesothelioma

PURPOSE

Ovarian/primary peritoneal serous carcinoma (OC/PPC) and diffuse peritoneal malignant mesothelioma (DMPM) are highly aggressive tumors that are closely related morphologically and histogenetically. It remains unclear whether both tumors are molecularly distinct neoplasms. The current study compared global gene expression patterns in OC/PPC and DMPM.

EXPERIMENTAL DESIGN

Ten OC/PPC and five DMPM effusions were analyzed for gene expression profiles using the Affymetrix U133 Plus 2 arrays and the dCHIP analysis program. Differentially expressed candidate genes were validated using quantitative real-time PCR and immunohistochemistry.

RESULTS

Unsupervised hierarchical clustering using all 54,675 genes in the array classified the samples into two groups: DMPM specimens versus OC/PPC specimens. A total of 189 genes that were differentially expressed in these two groups were selected based on statistical significance. Genes overexpressed in DMPM (n = 68) included calretinin, vitronectin, claudin 15, alpha4 laminin, hyaluronan synthase 1, cadherin 11, RAB7, v-maf, and the epidermal growth factor-containing fibulin-like extracellular matrix protein 1. Genes overexpressed in OC/PPC (n = 121) included insulin-like growth factor II (IGF-II); IGF-II binding protein 3; cyclin E1; folate receptors 1 and 3; RAB25; MUC4; endothelin-1; CD24; kallikreins 6, 7, and 8; claudins 3, 4, and 6; Notch3; and MMP-7. Quantitative real-time PCR validated the differential expression of 13 genes, and immunohistochemistry confirmed the differences for four gene products.

CONCLUSIONS

Expression profiling separates OC/PPC from DMPM and identifies a number of genes that are differentially expressed in these tumors. The molecular signatures unique to OC/PPC and DMPM should provide a molecular basis to study both tumors and new potential markers for facilitating their differential diagnosis.