[Imaging of the pelvic floor : The gynaecological perspective]. / Bildgebung des Beckenbodens : Die Sicht der Gynäkologie.

BACKGROUND: Pelvic floor dysfunction is common in women. OBJECTIVES: To describe the role of ultrasound in the urogynecological examination and imaging of the pelvic floor. MATERIALS AND METHODS: Analysis and summary of current recommendations and literature on the role of pelvic floor ultrasound. RESULTS: Pelvic floor ultrasound is a dynamic and real-time imaging modality. It is readily available, allows for a realistic assessment of anatomy and morphology, and poses minimal patient burden. CONCLUSIONS: Pelvic floor ultrasound is of great value in preoperative diagnostics as well as in the postoperative management of complications.

Determination of the Cancer Genome Atlas (TCGA) Endometrial Cancer Molecular Subtypes Using the Variant Interpretation and Clinical Decision Support Software MH Guide.

BACKGROUND: The Cancer Genome Atlas (TCGA) network (United States National Cancer Institute) identified four molecular endometrial cancer (EC) subtypes using an extensive multi-method approach. The aim of this study was to determine the four TCGA EC molecular subtypes using a single-method whole-exome sequencing (WES)-based approach provided by MH Guide (Molecular Health, Heidelberg, Germany). METHODS: WES and clinical data of n = 232 EC patients were obtained from TCGA. The four TCGA EC molecular subtypes designated as (i) Mutated Polymerase ε (POLE), (ii) Microsatellite Instability (MSI), (iii) Copy Number (CN) low and, (iv) CN-high were determined using the MH Guide software. The prognostic value of the subtypes determined by MH Guide were compared with the TCGA classification. RESULTS: Analysis of WES data using the MH Guide software led to the precise identification of the four EC molecular subtypes analogous to the TCGA classification. Both approaches displayed high concordance in terms of prognostic significance. CONCLUSIONS: The multi-method-based TCGA EC molecular subtypes can reliably be reproduced by the single-method-based MH Guide approach. The easy-to-implement single-method MH Guide approach represents a promising diagnostic tool.

Evaluation of the Diagnostic Potential of Circulating MicroRNAs miR-1 and miR-21 in Patients With Ovarian Cancer.

BACKGROUND/AIM: MicroRNA (miR) is implicated in the development of ovarian cancer (OC), the emergence of therapy resistance, and metastatic spread. In the past decade, a variety of relevant miRs have been identified in the context of OC, including miR-1 and miR-21. miR-21 plays a crucial role in OC carcinogenesis via activation of phosphatidylinositol-4,5-bisphosphate 3-kinase signaling and development of platinum resistance, and has prognostic value. miR-1 has been identified as a tumor suppressor across various cancer entities, with reduced expression in malignant tissue compared to benign. This evidence highlights the potential of miR-1 and miR-21 to serve as diagnostic and prognostic biomarkers in OC. PATIENTS AND METHODS: We studied the diagnostic potential of serum expression of miR-1 and miR-21 in a cohort comprising patients with malignant and benign ovarian tumors. Furthermore, levels of miR expression were analyzed with regard to clinical outcomes in patients with malignant ovarian tumors to evaluate their prognostic value. RESULTS: We identified significant differential expression of miR-1 (p=0.0397) and miR-21 (p=0.0154) in malignant and benign ovarian tumors: Higher expression of miR-1 was found in patients with benign ovarian tumors, whereas expression of miR-21 was higher in patients with malignant ovarian tumors. In receiver operating characteristic analyses, the diagnostic potential of both miRs was confirmed, however, diagnostic significance was inferior to that of cancer antigen 125. No further value, in particular no prognostic value, was obtained for miR-1 and miR-21 in patients with malignant ovarian tumors. CONCLUSION: Serum levels of miR-1 and miR-21 might serve as promising biomarkers in the diagnosis of ovarian cancer.

Characterization and Management of Borderline Ovarian Tumors - Results of a Retrospective, Single-center Study of Patients Treated at the Department of Gynecology and Obstetrics of the University Medicine Greifswald.

BACKGROUND/AIM: Borderline ovarian tumors (BOT) are malignant epithelial ovarian tumors with a very low incidence, therefore lacking sufficient clinical experience in diagnostics and treatment. This study characterized the histology, clinical features, diagnostics and therapy of BOT including patients treated at the Department of Gynecology and Obstetrics of the University Medicine Greifswald. MATERIALS AND METHODS: In this retrospective, single-center study, patients with BOT treated between 1990 and 2010 were analyzed according to their histological and clinical reports. RESULTS: A total of 54 patients were enrolled. The median age was 54.6 (range=23-83) years. Distribution of histological subtypes was: serous in 31 patients (57.4 %) and mucinous in 23 patients (42.6%). All patients underwent surgery. Eight patients (14.8%) were treated according to actual therapy recommendations during the initial surgery. Eight patients (14.8%) received adjuvant chemotherapy contrary to treatment recommendations. In the case of 36 patients (66.7%), a frozen section was taken intraoperatively, which matched the definitive histological result in 88.9%. During average follow-up of 70.3 months (range=0-231 months), two patients (3.7%) developed tumor recurrence after 9 and 29 months, respectively, two patients (3.7%) died of causes other than BOT. CONCLUSION: Our study critically demonstrated that until a few years ago, BOTs were not usually treated according to international therapy recommendations. Nevertheless, the rate of tumor recurrence was very low.

Functionality of the Tumor Suppressor microRNA-1 in Malignant Tissue and Cell Line Cells of Uterine Leiomyosarcoma.

BACKGROUND/AIM: Uterine leiomyosarcoma (uLMS) is a very rare mesenchymal tumor showing an aggressive clinical course and poor prognosis for patients. Due to the low incidence, little is known about molecular tumor biology and biomarkers of uLMS. Micro-RNA-1 (miR-1) has been identified as a pivotal tumor suppressor in numerous entities being suited as a molecular marker for tumor progression. MATERIALS AND METHODS: uLMS patient samples were analyzed regarding their miR-1 expression levels. Furthermore, miR-1 growth inhibitory and target regulatory properties were examined in transfected uLMS cells SK-UT-1. RESULTS: miR-1 was strongly suppressed in uLMS tumor tissue compared to adjacent healthy tissue. In vitro studies, however, failed to detect growth inhibitory properties of miR-1 in SK-UT-1 cells. The expression of the cell survival and MAP kinases Erk-1/2 and p38 was not targeted by miR-1. CONCLUSION: Tumor suppressive mechanisms of miR-1, seem to be inhibited in uLMS SK-UT-1 cells, maybe as part of the malignant transformation process. Regardless of the microRNA's cellular functionality, miR-1 may represent a promising biomarker of diagnosis in uLMS therapy.

Expression, Intracellular Localization, and Prognostic Value of Plasminogen Activator Inhibitor 1 and PAI-1 RNA-Binding Protein 1 in Primary and Recurrent Ovarian Cancer: A Study of the Tumor Bank Ovarian Cancer Network.

BACKGROUND: The plasminogen activator system plays a key role in ovarian cancer (OC) tumor progression. The plasminogen activator inhibitor type 1 (PAI-1) and the recently identified PAI-1 RNA binding protein 1 (PAI-RBP1) are primary regulators of plasminogen activation and thus are putative biomarkers for OC progression. METHODS: One hundred fifty six OC patients were analyzed to identify the presence of PAI-1 and PAI-RBP1 and subsequently correlated to clinicopathological parameters. Primary cells obtained from OC patient samples were applied in fluorescence microscopy analysis for examination of PAI-1 and PAI-RBP1 distribution. RESULTS: PAI-1 and PAI-RBP1 have been found to be predictive markers for OC patients' outcome. PAI-1 levels significantly correlated with volume of ascites, FIGO staging, and lymph node status. PAI-RBP1 expression significantly correlated with age at first diagnosis, histological tumor type, presence of distant metastasis (pM), and recurrence. PAI-1 showed a trend toward association and PAI-RBP1 was significantly associated with progression-free survival. Notably, PAI-1 protein in recurrent OC tissues was exclusively localized in the nucleus. CONCLUSION: This study has shown that a combination of PAI-1 and PAI-RBP1 may represent novel prognostic factor for OC. Prospective trials are needed.

Cold Atmospheric Plasma (CAP) and CAP-Stimulated Cell Culture Media Suppress Ovarian Cancer Cell Growth - A Putative Treatment Option in Ovarian Cancer Therapy.

BACKGROUND/AIM: Ovarian cancer (OC) is a gynecologic tumor with poor prognosis. Despite radical cytoreductive surgery and platinum-based adjuvant systemic treatment, OC will relapse in the majority of the cases. Thus, cold atmospheric plasma (CAP), a highly reactive physical state bearing diverse biological activities being suited for anticancer therapy, may be a promising option in OC therapy. MATERIALS AND METHODS: OC cell lines were exposed either directly to the CAP or to cell culture medium previously exposed to CAP. Cell proliferation and cell motility was measured. RESULTS: The data demonstrated, that even a single application of a short-term CAP treatment led to an attenuation of OC cell growth and motility. Moreover, incubation with CAP-treated cell culture medium gave similar effects. Results were consistent in four OC cell lines. CONCLUSION: In summary, the CAP application in oncological surgery leads to strong anti-proliferative effects and opens up novel opportunities for the OC treatment.

Y-box Binding Protein-1 Enhances Oncogenic Transforming Growth Factor ß Signaling in Breast Cancer Cells via Triggering Phospho-Activation of Smad2.

BACKGROUND/AIM: Transforming growth factor ß (TGFß) plays a role in diverse oncogenic pathways including cell proliferation and cell motility and is regulated by the pleiotropic factor Y-box binding protein-1 (YB-1). In breast cancer, Sma/Mad related protein 2 (Smad2) represents the most common downstream transducer in TGFß signaling. MATERIALS AND METHODS: Here, YB-1's impact on Smad2 phospho-activation was characterized by incubation of the breast cancer cell line MCF-7 with or without TGFß1 in the absence or presence of overexpressed YB-1 protein. The phospho-status of Smad2 was assessed via western blotting. RESULTS: Analysis of MCF-7 cells revealed no induction of total Smad2 neither in the presence of TGFß1, nor during YB-1 overexpression. In contrast, incubation with TGFß1 led to an increase of phosphorylated Smad2 forms which was significantly amplified by simultaneously overexpressed YB-1 (2.8±0.2-fold). CONCLUSION: Oncogenic YB-1 indirectly enhances TGFß signaling cascades via Smad2 phospho-activation and may represent a promising factor for future diagnosis and therapy of breast cancer.

Heat Shock Protein HSP27 Secretion by Ovarian Cancer Cells Is Linked to Intracellular Expression Levels, Occurs Independently of the Endoplasmic Reticulum Pathway and HSP27's Phosphorylation Status, and Is Mediated by Exosome Liberation.

The heat shock protein HSP27 has been correlated in ovarian cancer (OC) patients with aggressiveness and chemoresistance and, therefore, represents a promising potential biomarker for OC diagnosis, prognosis, and treatment response. Notably, secretion of soluble HSP27 has been described by a few cell types and may take place as well in OC cells. Therefore, we studied HSP27 secretion mechanisms under diverse cellular conditions in an OC cell model system. Secretion of HSP27 was characterized after overexpression of HSP27 by transfected plasmids and after heat shock. Intra- and extracellular HSP27 amounts were assessed by Western blotting and ELISA. Protein secretion was blocked by brefeldin A and the impact of the HSP27 phosphorylation status was analyzed overexpressing HSP27 phosphomutants. The present study demonstrated that HSP27 secretion by OVCAR-3 and SK-OV-3 cells depends on intracellular HSP27 concentrations. Moreover, HSP27 secretion is independent of the endoplasmic reticulum secretory pathway and HSP27 phosphorylation. Notably, analysis of OC cell-born exosomes not only confirmed the concentration-dependent correlation of HSP27 expression and secretion but also demonstrated a concentration-dependent incorporation of HSP27 protein into exosomes. Thus, secreted HSP27 may become more important as an extracellular factor which controls the tumor microenvironment and might be a noninvasive biomarker.

Clinical Outcome of Neoadjuvant Radiochemotherapy in Locally Advanced Cervical Cancer: Results of an Open Prospective, Multicenter Phase 2 Study of the North-Eastern German Society of Gynecological Oncology.

OBJECTIVE: The aim of this study was to determine the response rate, toxicity, operability, and surgical complication rate of neoadjuvant concomitant radiochemotherapy (cRCH) (ifosfamide + carboplatin) followed by radical hysterectomy plus external-beam radiotherapy with curative intention in locally advanced primary inoperable stages IIB and IIIB squamous cell cervical cancer. METHODS: Patients with cervical cancer from 8 departments were enrolled. Patients received 3 cycles of ifosfamide 1.2 mg/m (+mesna 20%) plus carboplatin (area under the curve = 4), every 21 days, and concomitant external-beam radiotherapy (50.4 Gy [1.8 Gy/d]). Operability and remission were evaluated by clinical gynecological examination in general anesthesia (magnetic resonance imaging was optional), 4 weeks after the third cycle of cRCH. In case of achieved operability, a radical hysterectomy with pelvic lymphadenectomy was performed within 6 weeks after cRCH. If surgery was not performed because of incomplete remission or patient preferences, vaginal brachytherapy (15 Gy [5 Gy/d]) was given additionally. RESULTS: Forty-four patients were enrolled. Distribution of FIGO (International Federation of Gynecology and Obstetrics) tumor stage was as follows: IIB (19 patients) and IIIB (25 patients). All patients completed cRCH. Grade 3/4 hematologic toxicities (% of all cycles) were moderate: leukopenia, 7.3; thrombocytopenia, 2.4; and anemia, 3.2. In 13.8%, treatment cycles were delayed because of hematologic toxicity. Blood transfusions were given in 17.7% and granulocyte colony-stimulating factor in 39.5%. Overall, grade 3/4 nonhematologic toxicities were seldom (6.5%). Clinical overall response rate was 95.2%. Operability was achieved in 85.7%. Surgery was performed in 83.3%. Pathological response rates were as follows: pathological complete remission, 33.3%; partial remission, 63.3%; stable disease, 3.3%. CONCLUSIONS: Our study demonstrates that cRCH is an effective and tolerable regimen in locally advanced cervical cancer treatment.

The future therapy of endometrial cancer: microRNA's functionality, capability, and putative clinical application.

PURPOSE: Endometrial cancer (EC) therapy is characterized by the heterogeneity of EC subtypes resulting in unclear clinical behavior as well as in unsatisfactory treatment options. The available biomarkers, such as cellular tumor antigen p53 (TP53), phosphatidylinositol 3,4,5-trisphosphate 3-phosphatase and dual-specificity protein phosphatase (PTEN), and phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) genes alone might not be sufficient, and thus, new predictive and prognostic biomarkers are urgently required. The biomolecule class of microRNA represents a group of endogenously expressed regulatory factors primarily involved in control of pivotal cancer-related mechanisms including cell cycle, proliferation, apoptosis, and metastasis. Here, we review the current state of science regarding microRNA functionality in EC progression.

The Tumor Suppressor MicroRNA-1 Exhibits Restricted Inhibition of Proliferation of Ovarian Cancer Cells.

BACKGROUND: MicroRNAs are able to control vital tumor biological processes, such as proliferation, tissue transformation and cell migration, as well as apoptosis. One of the micro RNAs, namely miR-1, has been classified as a tumor suppressor, however, preliminary data did not confirm this finding in ovarian cancer (OC) cells. This study examined the impact of miR-1 on OC cell growth. MATERIALS AND METHODS: Recombinant miR-1 was overexpressed in human OC cell lines OVCAR-3, SK-OV-3, TOV-112D, and TOV-21G. Subsequently, cell growth was analyzed. RESULTS: After transfection, 11- to 487-fold overexpression of miR-1 was detectable in the OC cells. However, no significant differences in proliferation compared to control cells were detected, neither in transiently nor in stably transfected cells. CONCLUSION: In numerous cancer entities miR-1 is defined as an antiproliferative tumor suppressor. Notably, the present study demonstrated a loss of growth-inhibitory functionality of miR-1 by so far unknown mechanisms, suggesting dysregulated miR-1 signaling or effector cascades in OC cells.

Drug-induced Modulation of Heat Shock Protein HSPB1 in an Ovarian Cancer Cell Model.

BACKGROUND: Heat-shock protein HSPB1 (alternative name HSP27) plays a pivotal role in cell survival pathways, apoptosis, metastasis and has been frequently linked to treatment resistance in ovarian cancer (OC) and other malignancies. Characteristic HSPB1 induction in different solid tumors is often caused by cytotoxic agents. MATERIALS AND METHODS: An in vitro OC cell model system was established to characterize resistance mechanisms during chemotherapy. Human OC cell lines OVCAR-3, SK-OV-3 and TOV-21G were treated with paclitaxel or carboplatin. Cellular growth was analyzed by cell counting. Intra- and extracellular HSPB1 concentrations were assessed by western blot and enzyme-linked immunosorbent assays. RESULTS: Incubation with paclitaxel, and with carboplatin significantly reduced cell growth without a definitive increase of intracellular HSPB1 expression. HSPB1 demonstrated drug-inducible secretion into the extracellular compartment. CONCLUSION: Despite its current lack of analysis in patient samples, serum soluble HSPB1 may function as a specific biomarker for monitoring response to chemotherapy in patients with OC.

Polo-like kinase Plk2 is an epigenetic determinant of chemosensitivity and clinical outcomes in ovarian cancer.

Resistance to platinum- and taxane-based chemotherapy remains a major clinical impediment to effective management of epithelial ovarian cancer (EOC). To gain insights into resistance mechanisms, we compared gene and confirmed expression patterns of novel EOC cell lines selected for paclitaxel and carboplatin resistance. Here, we report that resistance can be conferred by downregulation of the Polo-like kinase Plk2. Mechanistic investigations revealed that downregulation occurred at the level of transcription via associated DNA methylation of the CpG island in the Plk2 gene promoter in cell lines, primary tumors, and patient sera. Inhibitory RNA (RNAi)-mediated knockdown and ectopic overexpression established a critical functional role for Plk2 in determining apoptotic sensitivity to paclitaxel and carboplatin. In drug-resistant human EOC cell lines, Plk2 promoter methylation varied with the degree of drug resistance and transcriptional silencing of the promoter. RNAi-dependent knockdown of Plk2 abrogated G(2)-M cell-cycle blockade by paclitaxel, conferring resistance to both paclitaxel and platinum. Conversely, ectopic expression of Plk2 restored sensitivity to G(2)-M cell-cycle blockade and cytotoxicity triggered by paclitaxel. In clinical cases, DNA methylation of the Plk2 CpG island in tumor tissue was associated with a higher risk of relapse in patients treated postoperatively with carboplatin and paclitaxel (P = 0.003). This trend was also reflected in the analysis of matched serum samples. Taken together, our results implicate Plk2 as a clinically important determinant of chemosensitivity, in support of the candidacy of Plk2 as a theranostic marker to inform EOC management.

Psychometric validation of the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Endometrial Cancer Module (EORTC QLQ-EN24).

AIM: A validation study was conducted to evaluate the psychometric properties of the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire-Endometrial Cancer Module (EORTC QLQ-EN24). This module was designed to assess disease and treatment specific aspects of the quality of life (QoL) of patients with endometrial cancer. METHODS: Two hundred and sixty-eight women with endometrial cancer were recruited in different phases of treatment: after pelvic surgery (Group 1); during adjuvant chemotherapy and/or radiotherapy (Group 2); after completion of treatment (Group 3). Patients completed the EORTC QLQ-C30, the endometrial cancer module and a short debriefing questionnaire. RESULTS: Multi-trait scaling analyses confirmed the hypothesised scale structure of the QLQ-EN24. Internal consistency reliability was good with Cronbach's alpha coefficients ranging from 0.74 to 0.86 (lymphoedema 0.80, urological symptoms 0.75, gastrointestinal symptoms 0.74, body image problems 0.86 and sexual/vaginal problems 0.86). Convergent and discriminant validity did not show any scaling errors for the subscales. The QLQ-EN24 module discriminated well between clinically different groups of patients. All items exhibited a high completion rate with less than 2% missing values except for the sexuality items (19%). CONCLUSION: The validation study supports the reliability, the convergent and divergent validity of the EORTC QLQ-EN24. This newly developed QLQ-EN24 module is a useful instrument for the assessment of the QoL in patients treated for endometrial cancer in clinical trials.

Expression and localization of e-cadherin in epithelial ovarian cancer.

BACKGROUND: Findings for the role of E-cadherin in ovarian cancer (OC) are controversial. The aim of this study was to analyze the expression and prognostic role of E-cadherin in OC. MATERIALS AND METHODS: Expression analysis of E-cadherin was performed by immunohistochemistry in 36 patients (12 primary OC, 15 recurrent OC, 9 benign ovarian lesions). Tumor specimens were collected within OC. Correlation analysis with clinicopathological factors and survival was performed. RESULTS: E-Cadherin was significantly reduced in OC compared to benign ovarian lesions (p=0.024). In primary OC, E-cadherin was comparable in ovarian tumor and corresponding metastatic tumor tissue. E-Cadherin showed no association with clinicopathological factors. A significant correlation between increased volume of ascites and higher E-cadherin immunoexpression was found in primary OC (p=0.029). E-Cadherin expression showed no statistically prognostic significance for survival (p=0.856). CONCLUSION: The function of E-cadherin in OC remains controversial and needs to be elucidated further in larger studies.

Expression of classical NF-kappaB pathway effectors in human ovarian carcinoma.

AIMS: Functional studies have demonstrated that nuclear factor (NF)-kappaB promotes tumour progression in ovarian cancer cells. However, surprisingly little is known of the expression of effectors of the NF-kappaB pathway in human ovarian cancer in vivo. METHODS AND RESULTS: Immunohistochemistry and in situ hybridization revealed that in a cohort of 85 primary ovarian carcinomas, total p65 expression was inversely correlated to nuclear and cytoplasmic phospho-IkappaBalpha (P = 0.002 and P = 0.05, respectively), and IkappaBalpha mRNA expression (P = 0.032). In contrast, phospho-p65 expression was paralleled by the expression of nuclear (P = 0.027) and cytoplasmic phospho-IkappaBalpha (P = 0.01). Total p65 expression was an adverse prognostic factor for overall survival (P = 0.018). In contrast, total IkappaBalpha and phosphorylated nuclear and cytoplasmic IkappaBalpha expression were favourable prognostic markers (P = 0.001, P = 0.031, P = 0.001, respectively). Cytoplasmic phospho-IkappaBalpha expression remained a significant prognostic factor on multivariate analysis (P = 0.010). In cultured, stimulated OVCAR-3 ovarian cancer cells the cytoplasmic retranslocation of p65 was delayed by inhibition of the nuclear membrane transporter chromosomal region maintenance/exportin1 protein (CRM1). A positive association of p65 and CRM1 expression was demonstrated in ovarian cancer tissue (P < 0.0001). CONCLUSIONS: Total and phosphorylated IkappaBalpha protein expression might serve as markers for NF-kappaB activation in human ovarian carcinoma. Cytoplasmic localization of p65 may be related to deregulated nucleocytoplasmic transport in carcinomas overexpressing CRM1.

Development of the Berlin Symptom Checklist Ovary (BSCL-O) for the measurement of quality of life of patients with primary and recurrent ovarian cancer: results of a phase I and II study.

GOALS OF WORK: Quality of life (Qol) represents a relevant end point in the clinical management of advanced ovarian cancer (AOC). However, there exist only a few specific instruments which have been designed for patients with ovarian cancer. The aim of this study was to develop a systematic checklist (Berlin Symptom Checklist Ovary (BSCL-O)) as an instrument of Qol for patients with AOC and to discriminate between the frequency and the importance of symptoms. PATIENTS AND METHODS: The main symptoms were identified in a phase I study via free interviews of five patients with ovarian cancer (OC) as well as five medical doctors, family dependent, and care workers. In the phase II study, the capability of BSCL-O was evaluated by questionnaire-guided interviews of 200 patients with primary OC, recurrent OC, metastasized breast cancer, and benign ovarian tumors. MAIN RESULTS: In phase I, 36 main symptoms were identified. In phase II, 7,200 answers from 98.5% of all patients were evaluable. Of the 36 symptoms of the BSCL-O, 23 revealed clinical relevance. There was a correlation of frequency and importance of symptoms (p < 0.05). The symptoms of the BSCL-O were deemed twice as strenuous in patients with recurrent OC. CONCLUSIONS: The BSCL-O can measure Qol of patients with OC. The BSCL-O is being validated in a phase III study.

Epigenetic silencing of argininosuccinate synthetase confers resistance to platinum-induced cell death but collateral sensitivity to arginine auxotrophy in ovarian cancer.

Evidence indicates that acquired resistance of cancers to chemotherapeutic agents can occur via epigenetic mechanisms. Down-regulation of expression of argininosuccinate synthetase (ASS1), the rate-limiting enzyme in the biosynthesis of arginine, has been associated with the development of platinum resistance in ovarian cancer treated with platinum-based chemotherapy. The aim of the present study was to analyse epigenetic regulation of ASS1 in ovarian cancer tissue taken at diagnosis and relapse and determine its significance as a predictor of clinical outcome in patients treated with platinum-based chemotherapy. In addition, expression and epigenetic regulation of ASS1 were analysed in human ovarian cancer cell lines, and ASS1 expression correlated with the ability of the lines to grow in media containing cisplatin, carboplatin or taxol or in arginine-depleted media. Our results show that aberrant methylation in the ASS1 promoter correlated with transcriptional silencing in ovarian cancer cell lines. ASS1 silencing conferred selective resistance to platinum-based drugs and conferred arginine auxotrophy and sensitivity to arginine deprivation. In ovarian cancer, ASS1 methylation at diagnosis was associated with significantly reduced overall survival (p = 0.01) and relapse-free survival (p = 0.01). In patients who relapse, ASS1 methylation was significantly more frequent at relapse (p = 0.008). These data establish epigenetic inactivation of ASS1 as a determinant of response to platinum chemotherapy and imply that transcriptional silencing of ASS1 contributes to treatment failure and clinical relapse in ovarian cancer. The collateral sensitivity of cells lacking endogenous ASS1 to arginine depletion suggests novel therapeutic strategies for the management of relapsed ovarian cancer.