Molecular pathogenesis of ovarian borderline tumors: new insights and old challenges

Molecular landscape of borderline ovarian tumours: A systematic review

Borderline ovarian tumours (BOTs) show intriguing characteristics distinguishing them from other ovarian tumours. The aim of the systematic review was to analyse the spectrum of molecular changes found in BOTs and discuss their significance in the context of the overall therapeutic approach. The systematic review included articles published between 2000 and 2023 in the databases: PubMed, EMBASE, and Cochrane. After a detailed analysis of the available publications, we qualified for the systematic review: 28 publications on proto-oncogenes: BRAF, KRAS, NRAS, ERBB2, and PIK3CA, 20 publications on tumour suppressor genes: BRCA1/2, ARID1A, CHEK2, PTEN, 4 on adhesion molecules: CADM1, 8 on proteins: B-catenin, claudin-1, and 5 on glycoproteins: E-Cadherin. In addition, in the further part of the systematic review, we included eight publications on microsatellite instability and three describing loss of heterozygosity in BOT. Molecular changes found in BOTs can vary on a case-by-case basis, identifying carcinogenic mutations through molecular analysis and developing targeted therapies represent significant advancements in the diagnosis and treatment of ovarian malignancies. Molecular studies have contributed significantly to our understanding of BOT pathogenesis, but substantial research is still required to elucidate the relationship between ovarian neoplasms and extraneous disease, identify accurate prognostic indicators, and develop targeted therapeutic approaches.

Borderline ovarian tumor and MRI evaluation of a case report

Borderline ovarian tumors or atypical proliferative tumors are abnormal cells that arise from ovarian epithelium in contrast to ovarian cancers which form from stroma, the supportive tissue of ovaries. They are not invasive and tend to grow slowly. Many patients with BOTs are asymptomatic, while others have nonspecific symptoms like abdominal pain or abdominal distension. The absence of symptoms makes Borderline Ovarian Tumor hard to diagnose until it is in an advanced size or stage. Very rarely, the borderline tumor cells change into cancer cells. It usually affects patients at the reproductive age, for whom preserving the childbearing potential plays a very important role.

In this report, we present the case of 58-year-old female patient who is presented to the neurosurgeon's office with complaints of lower abdominal pain. Incidentally while investigating the intervertebral discs through a lumbar MRI, an abnormal finding was present in the coronal view, where a mass was noted on the lower right adnexal region of the abdomen. The patient was referred to a gynecologist for further investigations,

This case report emphasizes the high sensitivity and specificity of contrast MRI in the diagnosis of various pelvic pathologies in female patients.

The Many Faces of Serous Neoplasms and Related Lesions of the Female Pelvis: A Review

Ovarian serous tumors and related lesions are one of the most common conditions of the female genital tract. While ovarian high-grade serous carcinoma carries high mortality and adverse prognosis, most other serous lesions have better clinical behavior. In recent years, significant progress has been made in understanding the nature and histogenesis of these lesions that has contributed to better and more precise clinical management. Most of the high-grade serous carcinomas involve the ovaries and/or peritoneum, although in most cases, their origin seems to be in the fallopian tube. This view is supported by the recognition of precursor lesions in the fallopian tube, such as p53 signature and serous tubular in situ carcinoma. This paper presents salient morphologic, immunohistochemical, and molecular data related to serous tumors and related lesions of the female pelvis and discusses the histogenetic interrelationship among these lesions in light of current knowledge.

Association of recurrent mutations in BRCA1, BRCA2, RAD51C, PALB2, and CHEK2 with the risk of borderline ovarian tumor

Background

There are several genes associated with ovarian cancer risk. Molecular changes in borderline ovarian tumor (BOT) indicate linkage of this disease to type I ovarian tumors (low-grade ovarian carcinomas). This study determined the prevalence and association of mutations in BRCA1, BRCA2, PALB2, RAD51C, and CHEK2 with the risk of BOTs.

Methods

The study group consisted of 102 patients with histologically confirmed BOT and 1743 healthy controls. In addition, 167 cases with ovarian cancer G1 were analyzed. The analyses included genotyping of 21 founder and recurrent mutations localized in 5 genes (BRCA1, BRCA2, PALB2, RAD51C, and CHEK2). The risk for developing BOT and low-grade ovarian cancer, as well as the association of tested mutations with survival, was estimated.

Results

The CHEK2 missense mutation (c.470T>C) was associated with 2-times increased risk of BOT (OR=2.05, p=0.03), at an earlier age at diagnosis and about 10% worse rate of a 10-year survival. Mutations in BRCA1 and PALB2 were associated with a high risk of ovarian cancer G1 (OR=8.53, p=0.005 and OR=7.03, p=0.03, respectively) and were related to worse all-cause survival for BRCA1 carriers (HR=4.73, 95%CI 1.45–15.43, p=0.01).

Conclusions

Results suggest that CHEK2 (c.470T>C) may possibly play a role in the pathogenesis of BOT, but due to the low number of BOT patients, obtained results should be considered as preliminary. Larger more in-depth studies are required.

Dysregulated Immunological Functionome and Dysfunctional Metabolic Pathway Recognized for the Pathogenesis of Borderline Ovarian Tumors by Integrative Polygenic Analytics

The pathogenesis and molecular mechanisms of ovarian low malignant potential (LMP) tumors or borderline ovarian tumors (BOTs) have not been fully elucidated to date. Surgery remains the cornerstone of treatment for this disease, and diagnosis is mainly made by histopathology to date. However, there is no integrated analysis investigating the tumorigenesis of BOTs with open experimental data. Therefore, we first utilized a functionome-based speculative model from the aggregated obtainable datasets to explore the expression profiling data among all BOTs and two major subtypes of BOTs, serous BOTs (SBOTs) and mucinous BOTs (MBOTs), by analyzing the functional regularity patterns and clustering the separate gene sets. We next prospected and assembled the association between these targeted biomolecular functions and their related genes. Our research found that BOTs can be accurately recognized by gene expression profiles by means of integrative polygenic analytics among all BOTs, SBOTs, and MBOTs; the results exhibited the top 41 common dysregulated biomolecular functions, which were sorted into four major categories: immune and inflammatory response-related functions, cell membrane- and transporter-related functions, cell cycle- and signaling-related functions, and cell metabolism-related functions, which were the key elements involved in its pathogenesis. In contrast to previous research, we identified 19 representative genes from the above classified categories (IL6, CCR2 for immune and inflammatory response-related functions; IFNG, ATP1B1, GAS6, and PSEN1 for cell membrane- and transporter-related functions; CTNNB1, GATA3, and IL1B for cell cycle- and signaling-related functions; and AKT1, SIRT1, IL4, PDGFB, MAPK3, SRC, TWIST1, TGFB1, ADIPOQ, and PPARGC1A for cell metabolism-related functions) that were relevant in the cause and development of BOTs. We also noticed that a dysfunctional pathway of galactose catabolism had taken place among all BOTs, SBOTs, and MBOTs from the analyzed gene set databases of canonical pathways. With the help of immunostaining, we verified significantly higher performance of interleukin 6 (IL6) and galactose-1-phosphate uridylyltransferase (GALT) among BOTs than the controls. In conclusion, a bioinformatic platform of gene-set integrative molecular functionomes and biophysiological pathways was constructed in this study to interpret the complicated pathogenic pathways of BOTs, and these important findings demonstrated the dysregulated immunological functionome and dysfunctional metabolic pathway as potential roles during the tumorigenesis of BOTs and may be helpful for the diagnosis and therapy of BOTs in the future.

The Era of Radiogenomics in Precision Medicine: An Emerging Approach to Support Diagnosis, Treatment Decisions, and Prognostication in Oncology

With the rapid development of new technologies, including artificial intelligence and genome sequencing, radiogenomics has emerged as a state-of-the-art science in the field of individualized medicine. Radiogenomics combines a large volume of quantitative data extracted from medical images with individual genomic phenotypes and constructs a prediction model through deep learning to stratify patients, guide therapeutic strategies, and evaluate clinical outcomes. Recent studies of various types of tumors demonstrate the predictive value of radiogenomics. And some of the issues in the radiogenomic analysis and the solutions from prior works are presented. Although the workflow criteria and international agreed guidelines for statistical methods need to be confirmed, radiogenomics represents a repeatable and cost-effective approach for the detection of continuous changes and is a promising surrogate for invasive interventions. Therefore, radiogenomics could facilitate computer-aided diagnosis, treatment, and prediction of the prognosis in patients with tumors in the routine clinical setting. Here, we summarize the integrated process of radiogenomics and introduce the crucial strategies and statistical algorithms involved in current studies.

The Diagnosis, Treatment, Prognosis and Molecular Pathology of Borderline Ovarian Tumors: Current Status and Perspectives

Borderline ovarian tumors (BOTs) are a type of low malignant potential tumor that is typically associated with better outcomes than ovarian cancer. Indeed, its 10-year survival rate is as high as 95%. However, there is a small subset of patients who experience relapse and eventually die. It has been shown that the prognosis of BOTs was based on pathological diagnosis, the age at diagnosis, pre-operative carbohydrate antigen 125 level, invasive implants, and micropapillary patterns. Now the molecular-targeted therapy and molecular-genetic diagnosis have developed into a form of precision medicine. Recent studies on extensive molecular characterizations and molecular pathological mechanisms of BOTs have helped us understand the genomic landscapes of BOTs, and therefore BOTs could be reclassified into biologically and clinically more accurate and effective subtypes. The purpose of this review is to summarize current status for the diagnosis and treatment of BOTs and to describe the research progress on molecular pathologies, with a goal of providing a theoretical perspective for the diagnosis and treatment of BOTs.

Oncogenic BRAF and KRAS mutations in endosalpingiosis

Endosalpingiosis, a microscopic lesion composed of ectopic Fallopian tube epithelium, frequently involves the peritoneum and lymph nodes in patients with ovarian serous borderline tumour or low-grade serous carcinoma, but its pathogenic significance remains unclear. Using laser-capture microdissection and droplet digital PCR, we investigated whether endosalpingiosis harbours the driver mutations in BRAF and KRAS that characterise ovarian low-grade serous neoplasms. Somatic mutations were detected in 14 (33%) of 43 endosalpingiotic lesions analysed. Of 21 women with endosalpingiosis associated with a synchronous or metachronous ovarian low-grade serous tumour, mutations were identified in endosalpingiotic lesions from 11 (52%) women, with most cases (10/11, 91%) demonstrating identical mutations in both tumour and endosalpingiosis. In contrast, of 13 cases of endosalpingiosis not associated with an ovarian tumour, only one harboured a KRAS mutation. The proliferative activity as assessed by Ki-67 immunohistochemistry was lower in endosalpingiosis than in low-grade serous tumours, and endosalpingiosis with either a BRAF or KRAS mutation had a significantly lower Ki-67 index than those without. Ectopic expression of KRAS^G12V in Fallopian tube epithelial cells led to ERK phosphorylation, p21 induction, growth arrest and cellular senescence. In conclusion, we demonstrate that endosalpingiosis represents an interesting example of cancer driver mutations in deceptively normal-appearing cells, which may be prone to neoplastic transformation upon bypass of endogenous oncosuppressive mechanisms. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Molecular Classification of Epithelial Ovarian Cancer Based on Methylation Profiling: Evidence for Survival Heterogeneity

PURPOSE

Ovarian cancer is a heterogeneous disease that can be divided into multiple subtypes with variable etiology, pathogenesis, and prognosis. We analyzed DNA methylation profiling data to identify biologic subgroups of ovarian cancer and study their relationship with histologic subtypes, copy number variation, RNA expression data, and outcomes.

EXPERIMENTAL DESIGN

A total of 162 paraffin-embedded ovarian epithelial tumor tissues, including the five major epithelial ovarian tumor subtypes (high- and low-grade serous, endometrioid, mucinous, and clear cell) and tumors of low malignant potential were selected from two different sources: The Polish Ovarian Cancer study, and the Surveillance, Epidemiology, and End Results Residual Tissue Repository (SEER RTR). Analyses were restricted to Caucasian women. Methylation profiling was conducted using the Illumina 450K methylation array. For 45 tumors array copy number data were available. NanoString gene expression data for 39 genes were available for 61 high-grade serous carcinomas (HGSC).

RESULTS

Consensus nonnegative matrix factorization clustering of the 1,000 most variable CpG sites showed four major clusters among all epithelial ovarian cancers. We observed statistically significant differences in survival (log-rank test, P = 9.1 × 10^-7) and genomic instability across these clusters. Within HGSC, clustering showed three subgroups with survival differences (log-rank test, P = 0.002). Comparing models with and without methylation subgroups in addition to previously identified gene expression subtypes suggested that the methylation subgroups added significant survival information (P = 0.007).

CONCLUSIONS

DNA methylation profiling of ovarian cancer identified novel molecular subgroups that had significant survival difference and provided insights into the molecular underpinnings of ovarian cancer.See related commentary by Ishak et al., p. 5729.

Loss of 1p36.33 Frequent in Low-Grade Serous Ovarian Cancer

BACKGROUND: Low-grade serous ovarian cancer (LGSOC) is a rare subtype of epithelial ovarian carcinoma. Limited data regarding the molecular-genetic background exist beyond mutations in the RAS signaling pathway. There is a growing need to better characterize these tumors due to chemoresistance and limited therapeutic options in advanced or recurrent disease. METHODS: We performed genome-wide copy number aberration (CNA) profiles and mutation hotspot screening (KRAS, BRAF, NRAS, ERBB2, PIK3CA, TP53) in 38 LGSOC tumor samples. RESULTS: We detected mutations in the RAS-signaling pathway in 36.8% of cases, including seven KRAS, four BRAF, and three NRAS mutations. We identified two mutations in PIK3CA and one mutation in MAP3K1, EGFR, and TP53. CNAs were detected in 86.5% of cases. None of the focal aberrations was correlated with specific clinical characteristics. The most frequently detected CNA was loss of 1p36.33 in 54.1% of cases, with a trend towards lower progression-free survival and overall survival in patients with 1p36.33 loss. CONCLUSIONS: Activating RAS mutations were dominant in our series, with supplementary detection of two PIK3CA mutations which may lead to therapeutic options. Furthermore, we detected 1p36.33 deletions in half of the cases, indicating a role in tumorigenesis, and these deletions may serve as a prognostic marker.

A rat model of serous borderline ovarian tumors induced by 7,12-dimethylbenz[a]anthracene

Serous borderline ovarian tumors (SBOTs) behave between benign cystadenomas and carcinomas, and the effective detection and clinical management of SBOTs remain clinical challenges. Because it is difficult to isolate and enrich borderline tumor cells, a borderline animal model is in need. 7,12-dimethylbenz[a]anthracene (DMBA) is capable of inducing the initiation, promotion, and progression of serous ovarian tumors. This study aims to investigate the proper dosage and induction time of DMBA for rat models of SBOTs, and explore their morphological features demonstrated by magnetic resonance (MR) imaging and molecular genetic characteristics. Rats were randomly divided into six groups (1 mg/70 D, 2 mg/70 D, 3 mg/70 D, 2 mg/50 D, 2 mg/90 D, and 2 mg/110 D). The 3 mg/70 D group induced the most SBOTs (50.0%, 12/24). The micropapillary projections were shown on MR imaging, which was the characteristic of SBOTs. The Cyclin D1 characterizing an early pathogenetic event strongly expressed in induced serous benign tumors (SBTs). The immunoreactivity staining scores of P53 expression significantly increased from SBTs, SBOTs to serous ovarian carcinomas (SCAs), which elucidate that P53 might be a promising biomarker to grade serous ovarian tumors. Based on morphological and molecular genetic similarities, this rodent SBOT model was suitable for investigating the pathogenesis of serous ovarian tumors and developing an early detection strategy.

TFF3 Expression as Stratification Marker in Borderline Epithelial Tumors of the Ovary

Borderline tumors (BOT) of the ovary account for 10% to 20% of ovarian neoplasms. Like ovarian cancer, BOT encompass several different histological subtypes (serous, mucinous, endometrioid, clear cell, transitional cell and mixed) with serous (SBOT) and mucinous (MBOT) the most common. Current hypotheses suggest low-grade serous carcinoma may develop in a stepwise fashion from SBOT whereas the majority of high grade serous carcinomas develop rapidly presumably from inclusion cysts or ovarian surface epithelium. The pathogenesis of mucinous ovarian tumors is still puzzling. Molecular markers could help to better define relationships between such entities. Trefoil factor-3 (TFF3) is an estrogen-regulated gene associated with prognosis in different types of cancer. It has also been included in a recent marker panel predicting subtypes of ovarian carcinoma. We analyzed the expression of TFF3 by immunohistochemistry in a cohort of 137 BOT and its association with histopathological features. Overall expression rate of TFF3 was 21.9%. None of the BOT with serous and endometrioid histology displayed strong TFF3 expression. On the other hand, TFF3 was highly expressed in 61.4% of MBOT cases and 33.3% of BOT with mixed histology (P < 0.001) suggesting a potential function of the protein in that subtypes. Associations of TFF3 expression with FIGO stage and micropapillary pattern were significant in the overall cohort but confounded by their correlation with histological subtypes. The highly specific expression of TFF3 in MBOT may help to further clarify potential relationships of tumors with mucinous histology and warrants further studies.

KRAS/BRAF Analysis in Ovarian Low-Grade Serous Carcinoma Having Synchronous All Pathological Precursor Regions

Ovarian low-grade serous carcinoma is thought to begin as a serous cystadenoma or adenofibroma that progresses in a slow stepwise fashion. Among the low-grade serous carcinomas, there is a high frequency of activating mutations in the KRAS or BRAF genes; however, it remains unclear as to how these mutations contribute to tumor progression. This is the first report to track the histopathological progression of serous adenofibroma to low-grade serous carcinoma. Each stage was individually analyzed by pathological and molecular genetic methods to determine what differences occur between the distinct stages of progression.

The status of epidermal growth factor receptor in borderline ovarian tumours

The majority of borderline ovarian tumours (BOTs) behave in a benign fashion, but some may show aggressive behavior. The reason behind this has not been elucidated. The epidermal growth factor receptor (EGFR) is known to contribute to cell survival signals as well as metastatic potential of some tumours. EGFR expression and gene status have not been thoroughly investigated in BOTs as it has in ovarian carcinomas. In this study we explore protein expression as well as gene mutations and amplifications of EGFR in BOTs in comparison to a subset of other epithelial ovarian tumours. We studied 85 tumours, including 61 BOTs, 10 low grade serous carcinomas (LGSCs), 9 high grade serous carcinomas (HGSCs) and 5 benign epithelial tumours. EGFR protein expression was studied using immunohistochemistry. Mutations were investigated by Sanger sequencing exons 18-21 of the tyrosine kinase domain of EGFR. Cases with comparatively higher protein expression were examined for gene amplification by chromogenic in situ hybridization. We also studied the tumours for KRAS and BRAF mutations. Immunohistochemistry results revealed both cytoplasmic and nuclear EGFR expression with variable degrees between tumours. The level of nuclear localization was relatively higher in BOTs and LGSCs as compared to HGSCs or benign tumours. The degree of nuclear expression of BOTs showed no significant difference from that in LGSCs (mean ranks 36.48, 33.05, respectively, p=0.625), but was significantly higher than in HGSCs (mean ranks: 38.88, 12.61 respectively, p< 0.001) and benign tumours (mean ranks: 35.18, 13.00 respectively, p= 0.010). Cytoplasmic expression level was higher in LGSCs. No EGFR gene mutations or amplification were identified, yet different polymorphisms were detected. Five different types of point mutations in the KRAS gene and the V600E BRAF mutation were detected exclusively in BOTs and LGSCs. Our study reports for the first time nuclear localization of EGFR in BOTs. The nuclear localization similarities between BOTs and LGSCs and not HGSCs support the hypothesis suggesting evolution of LGSCs from BOTs. We also confirm that EGFR mutations and amplifications are not molecular events in the pathogenesis of BOTs.

Expression and promotor hypermethylation of miR-34a in the various histological subtypes of ovarian cancer

Background

An increasing body of evidence shows that miR-34 family has tumor suppressive properties mediating apoptosis, cell cycle arrest and senescence. In ovarian cancer, miR34 family members were found to be under expressed. Particularly miR-34a has been revealed to be a direct transcriptional target of p53 which is frequently mutated in epithelial ovarian carcinomas especially in high grade serous cancer. Moreover, methylation of miR-34a CpG Islands was found to down-regulate miR-34a expression. The aim of this study was to investigate the clinical relevance of mir34a as well as its promoter methylation in a subset of 133 ovarian cancers with a special focus on the p53 mutation status, the dualistic type I and type II ovarian cancer model and the different histotypes.

Methods

One hundred thirty-three epithelial ovarian cancers and 8 samples of healthy ovarian surface epithelium were retrospectively analysed for miR-34a expression with quantitative real-time reverse transcription PCR (qRT-PCR). Gene-specific DNA methylation was evaluated with MethyLight technique.

Results

Significantly lower miR-34a expression was found in ovarian cancers than in healthy ovarian epithelium (p = 0.002). The expression of miR-34a was found lower in type II than in type I cancers (p = 0.037), in p53 mutated as compared to p53 wild type cancers (p = 0.003) and in high grade compared to in low grade cancers (p = 0.028). In multivariate COX regression model low expressing miR-34a cancers exhibited a reduced PFS (p = 0.039) and OS (p = 0.018). In serous cancers low miR-34a levels showed a worse OS confirmed also in multivariate analysis (p = 0.022). miR-34a promoter methylation was found higher in type II cancers than in type I (p = 0.006). mir34a expression and promoter methylation showed an inverse correlation in cancer samples (p = 0.05).

Conclusion

We demonstrated a clinical independent role of miR-34a in epithelial ovarian cancers. Moreover, we corroborated the correlation between miR-34a expression and its promoter methylation in a large set of ovarian cancers. The inverse association between miR-34a expression and grading, p53 mutation status and dualistic tumor type classification, together with its prognostic relevance may underline the tumor-suppressive character of miR-34a in ovarian cancer.

Fascin-1 expression as stratification marker in borderline epithelial tumours of the ovary

AIMS

To evaluate the actin-bundling protein fascin-1 (FSCN1) as marker for borderline ovarian tumours (BOTs).

METHODS

We analysed a retrospective cohort of 140 BOTs with validated diagnosis by an independent pathologist. Immunohistochemical detection of FSCN1 was quantified as combined immunoreactive score (CIS) blinded to clinical patient data. Analyses were first performed for FSCN1 positive versus negative, and then verified using three categories derived from the observed distribution (negative, weak, strong; CIS 0, 1-2, 3-9).

RESULTS

We detected FSCN1 positivity in 51.4%, and strong expression (CIS 3-9) in 14.3% of the samples. FSCN1 positivity was associated with serous subtype (p<0.001) and micropapillary pattern (p<0.001). Correlation with micropapillary pattern remained significant within the serous BOT (SBOT) subgroup (p=0.022). Strong FSCN1 expression (CIS 3-9) was associated both with the presence of implants (p=0.022), and a higher International Federation of Gynecology and Obstetrics (FIGO) stage (p=0.020).

CONCLUSIONS

Our analysis links FSCN1 with SBOT with micropapillary pattern. Strong expression is associated with higher FIGO stage and the presence of implants, both related to elevated risk of recurrence. Hence, FSCN1 is an interesting marker worth further analyses of its prognostic value in BOTs.

BRAF mutation is associated with a specific cell type with features suggestive of senescence in ovarian serous borderline (atypical proliferative) tumors

Serous borderline tumor also known as atypical proliferative serous tumor (APST) is the precursor of ovarian low-grade serous carcinoma (LGSC). In this study, we correlated the morphologic and immunohistochemical phenotypes of 71 APSTs and 18 LGSCs with the mutational status of KRAS and BRAF, the most common molecular genetic changes in these neoplasms. A subset of cells characterized by abundant eosinophilic cytoplasm (EC), discrete cell borders, and bland nuclei was identified in all (100%) 25 BRAF-mutated APSTs but in only 5 (10%) of 46 APSTs without BRAF mutations (P<0.0001). Among the 18 LGSCs, EC cells were found in only 2, and both contained BRAF mutations. The EC cells were present admixed with cuboidal and columnar cells lining the papillae and appeared to be budding from the surface, resulting in individual cells and clusters of detached cells "floating" above the papillae. Immunohistochemistry showed that the EC cells always expressed p16, a senescence-associated marker, and had a significantly lower Ki-67 labeling index than adjacent cuboidal and columnar cells (P=0.02). In vitro studies supported the interpretation that these cells were undergoing senescence, as the same morphologic features could be reproduced in cultured epithelial cells by ectopic expression of BRAF(V600E). Senescence was further established by markers such as SA-β-gal staining, expression of p16 and p21, and reduction in DNA synthesis. In conclusion, this study sheds light on the pathogenesis of this unique group of ovarian tumors by showing that BRAF mutation is associated with cellular senescence and the presence of a specific cell type characterized by abundant EC. This "oncogene-induced senescence" phenotype may represent a mechanism that impedes progression of APSTs to LGSC.

Mutational status of KRAS, NRAS, and BRAF in primary clear cell ovarian carcinoma

Ovarian clear cell carcinoma (OCCC) is a subtype of epithelial ovarian cancer with characteristic biological features and aggressive clinical behavior. OCCCs show a pattern of gene mutations different from other type I ovarian malignancies, notably a higher frequency of PIK3CA mutations. In low grade serous ovarian cancer, KRAS and BRAF mutations are frequent, but little data are available on the mutational status of these genes in OCCCs. To clarify this issue, we designed a clinicopathological study with the aim to establish the incidence of KRAS, NRAS, and BRAF hot spot mutations in OCCC. Between December 2006 and June 2012, 22 patients with a proven diagnosis of OCCC were admitted to our Institutions. In all cases, final diagnosis was established according to FIGO and WHO criteria. All women received complete surgical staging. The PyroMark Q24 system (Qiagen GmbH, Hilden, Germany) was used for pyrosequencing analysis of KRAS, NRAS, and BRAF hot spot regions on 2.5-μm sections of formalin-fixed paraffin-embedded tissue from primary OCCC. Pyrosequencing analysis of KRAS, NRAS, and BRAF hot spot regions revealed the presence of mutations only at codon 12 in exon 2 of KRAS in 3 of 22 (14 %) cases. We found no mutations in the hot spot regions of NRAF (exons 2, 3, 4) or BRAF (exon 15). The median age of women with a KRAS mutated OCCC was 74 years. These OCCC were unilateral FIGO stage IA lesions in two cases associated with foci of endometriosis. We conclude that in 14 % of OCCCs, a KRAS mutation occurs in codon 2 exon 2. NRAS and BRAF mutations were not found.

An update on Mullerian-inhibiting substance: its potential application against ovarian cancer

Each year, ∼25 000 women are newly diagnosed with ovarian cancer in the USA. The vast majority (>90%) of cases are of epithelial origin. This highly lethal cancer carries a mortality rate of >50% and a high risk of recurrence after conventional, first-line chemotherapy. Müllerian-inhibiting substance (MIS) is a gonadal hormone that causes regression of the Müllerian ducts. A series of studies have demonstrated that MIS also has multiple extra-Müllerian functions including inhibition of epithelial ovarian cancer cells in vitro and in vivo. Accumulating evidence has shown that many human cancers are organized hierarchically and contain a small population of cancer stem cells (CSCs) that are inherently resistant to common chemotherapy and radiation therapy. The effect of MIS on ovarian CSC seems to be particularly useful in rescuing ovarian cancer patients with resistance to conventional treatment. Based on recent studies evaluating MIS, this review updates our current understanding of the molecular genetic aspects of MIS, its pathophysiology, as well as its potential to treat chemoresistant epithelial ovarian cancer.

KRAS (but not BRAF) mutations in ovarian serous borderline tumour are associated with recurrent low-grade serous carcinoma

BRAF and KRAS mutations in ovarian serous borderline tumours (OSBTs) and ovarian low-grade serous carcinomas (LGSCs) have been previously described. However, whether those OSBTs would progress to LGSCs or whether those LGSCs were developed from OSBT precursors in previous studies is unknown. Therefore, we assessed KRAS and BRAF mutations in tumour samples from 23 recurrent LGSC patients with a known initial diagnosis of OSBT. Paraffin blocks from both OSBT and LGSC samples were available for five patients, and either OSBTs or LGSCs were available for another 18 patients. Tumour cells from paraffin-embedded tissues were dissected out for mutation analysis by conventional polymerase chain reaction (PCR) and Sanger sequencing. Tumours that appeared to have wild-type KRAS by conventional PCR-Sanger sequencing were further analysed by full COLD (co-amplification at lower denaturation temperature)-PCR and deep sequencing. Full COLD-PCR was able to enrich the amplification of mutated alleles. Deep sequencing was performed with the Ion Torrent personal genome machine (PGM). By conventional PCR-Sanger sequencing, BRAF mutation was detected only in one patient and KRAS mutations were detected in ten patients. Full COLD-PCR deep sequencing detected low-abundance KRAS mutations in eight additional patients. Three of the five patients with both OSBT and LGSC samples available had the same KRAS mutations detected in both OSBT and LGSC samples. The remaining two patients had only KRAS mutations detected in their LGSC samples. For patients with either OSBT or LGSC samples available, KRAS mutations were detected in seven OSBT samples and six LGSC samples. Surprisingly, patients with the KRAS G12V mutation have shorter survival times. In summary, KRAS mutations are very common in recurrent LGSC, while BRAF mutations are rare. The findings indicate that recurrent LGSC can arise from proliferation of OSBT tumour cells with or without detectable KRAS mutations.

ARID1A mutations and PI3K/AKT pathway alterations in endometriosis and endometriosis-associated ovarian carcinomas

Endometriosis is a common gynecological disease affecting 6%–10% of women of reproductive age and is characterized by the presence of endometrial-like tissue in localizations outside of the uterine cavity as, e.g., endometriotic ovarian cysts. Mainly, two epithelial ovarian carcinoma subtypes, the ovarian clear cell carcinomas (OCCC) and the endometrioid ovarian carcinomas (EnOC), have been molecularly and epidemiologically linked to endometriosis. Mutations in the gene encoding the AT-rich interacting domain containing protein 1A (ARID1A) have been found to occur in high frequency in OCCC and EnOC. The majority of these mutations lead to a loss of expression of the ARID1A protein, which is a subunit of the SWI/SNF chromatin remodeling complex and considered as a bona fide tumor suppressor. ARID1A mutations frequently co-occur with mutations, leading to an activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, such as mutations in PIK3CA encoding the catalytic subunit, p110α, of PI3K. In combination with recent functional observations, these findings strongly suggest cooperating mechanisms between the two pathways. The occurrence of ARID1A mutations and alterations in the PI3K/AKT pathway in endometriosis and endometriosis-associated ovarian carcinomas, as well as the possible functional and clinical implications are discussed in this review.

Potential tumor biomarkers identified in ovarian cyst fluid by quantitative proteomic analysis, iTRAQ

BACKGROUND

Epithelial-derived ovarian adenocarcinoma (EOC) is the most deadly gynecologic tumor, and the principle cause of the poor survival rate is diagnosis at a late stage. Screening and diagnostic biomarkers with acceptable specificity and sensitivity are lacking. Ovarian cyst fluid should harbor early ovarian cancer biomarkers because of its closeness to the tumor. We investigated ovarian cyst fluid as a source for discovering biomarkers for use in the diagnosis of EOC.

RESULTS

Using quantitative mass spectrometry, iTRAQ MS, we identified 837 proteins in cyst fluid from benign, EOC stage I, and EOC stage III. Only patients of serous histology were included in the study. Comparing the benign (n = 5) with the malignant (n = 10) group, 87 of the proteins were significantly (p < 0.05) differentially expressed. Two proteins, serum amyloid A-4 (SAA4) and astacin-like metalloendopeptidase (ASTL), were selected for verification of the iTRAQ method and external validation with immunoblot in a larger cohort with mixed histology, in plasma (n = 68), and cyst fluid (n = 68). The protein selections were based on either high significance and high fold change or abundant appearance and several peptide recognitions in the sample sets (p = 0.04, FC = 1.95) and (p < 0.001, FC = 8.48) for SAA4 and ASTL respectively. Both were found to be significantly expressed (p < 0.05), but the methods did not correlate concerning ASTL.

CONCLUSIONS

Fluid from ovarian cysts connected directly to the primary tumor harbor many possible new tumor-specific biomarkers. We have identified 87 differentially expressed proteins and validated two candidates to verify the iTRAQ method. However several of the proteins are of interest for validation in a larger setting.

Frequency of mutations and polymorphisms in borderline ovarian tumors of known cancer genes

Borderline ovarian tumors represent an understudied subset of ovarian tumors. Most studies investigating aberrations in borderline tumors have focused on KRAS/BRAF mutations. In this study, we conducted an extensive analysis of mutations and single-nucleotide polymorphisms (SNPs) in borderline ovarian tumors. Using the Sequenom MassArray platform, we investigated 160 mutations/polymorphisms in 33 genes involved in cell signaling, apoptosis, angiogenesis, cell cycle regulation and cellular senescence. Of 52 tumors analyzed, 33 were serous, 18 mucinous and 1 endometrioid. KRAS c.35G>A p.Gly12Asp mutations were detected in eight tumors (six serous and two mucinous), BRAF V600E mutations in two serous tumors, and PIK3CA H1047Y and PIK3CA E542K mutations in a serous and an endometrioid BOT, respectively. CTNNB1 mutation was detected in a serous tumor. Potentially functional polymorphisms were found in vascular endothelial growth factor (VEGF), ABCB1, FGFR2 and PHLPP2. VEGF polymorphisms were the most common and detected at four loci. PHLPP2 polymorphisms were more frequent in mucinous as compared with serous tumors (P=0.04), with allelic imbalance in one case. This study represents the largest and most comprehensive analysis of mutations and functional SNPs in borderline ovarian tumors to date. At least 25% of borderline ovarian tumors harbor somatic mutations associated with potential response to targeted therapeutics.

Quaternary cytoreductive surgery in ovarian cancer: does surgical effort still matter?

Background:

To evaluate surgical outcome and survival benefit after quaternary cytoreduction (QC) in epithelial ovarian cancer (EOC) relapse.

Methods:

We systematically evaluated all consecutive patients undergoing QC in our institution over a 12-year period (October 2000–January 2012). All relevant surgical and clinical outcome parameters were systematically assessed.

Results:

Forty-nine EOC patients (median age: 57; range: 28–76) underwent QC; in a median of 16 months (range:2–142) after previous chemotherapy. The majority of the patients had an initial FIGO stage III (67.3%), peritoneal carcinomatosis (77.6%) and no ascites (67.3%). At QC, patients presented following tumour pattern: lower abdomen 85.7% middle abdomen 79.6% and upper abdomen 42.9%. Median duration of surgery was 292 min (range: a total macroscopic tumour clearance could be achieved. Rates of major operative morbidity and 30-day mortality were 28.6% and 2%, respectively.

Mean follow-up from QC was 18.41 months (95% confidence interval (CI):12.64–24.18) and mean overall survival (OS) 23.05 months (95% CI: 15.5–30.6). Mean OS for patients without vs any tumour residuals was 43 months (95% CI: 26.4–59.5) vs 13.4 months (95% CI: 7.42–19.4); P=0.001. Mean OS for patients who received postoperative chemotherapy (n=18; 36.7%) vs those who did not was 40.5 months (95% CI: 27.4–53.6) vs 12.03 months (95% CI: 5.9–18.18); P<0.001.

Multivariate analysis indentified multifocal tumour dissemination to be of predictive significance for incomplete tumour resection, higher operative morbidity and lower survival, while systemic chemotherapy subsequent to QC had a protective significant impact on OS. No prognostic impact had ascites, platinum resistance, high grading and advanced age.

Conclusion:

Even in this highly advanced setting of the third EOC relapse, maximal therapeutic effort combining optimal surgery and chemotherapy appear to significantly prolong survival in a selected patients ‘group’.

The DNA methylomes of serous borderline tumors reveal subgroups with malignant- or benign-like profiles

Serous borderline tumors (SBOTs) are a challenging group of ovarian tumors positioned between benign and malignant disease. We have profiled the DNA methylomes of 12 low-grade serous carcinomas (LGSCs), 19 SBOTs, and 16 benign serous tumors (BSTs) across 27,578 CpG sites to further characterize the epigenomic relationship between these subtypes of ovarian tumors. Unsupervised hierarchical clustering of DNA methylation levels showed that LGSCs differ distinctly from BSTs, but not from SBOTs. Gene ontology analysis of genes showing differential methylation at linked CpG sites between LGSCs and BSTs revealed significant enrichment of gene groups associated with cell adhesion, cell-cell signaling, and the extracellular region, consistent with a more invasive phenotype of LGSCs compared with BSTs. Consensus clustering highlighted differences between SBOT methylomes and returned subgroups with malignant- or benign-like methylation profiles. Furthermore, a two-loci DNA methylation signature can distinguish between these SBOT subgroups with benign- and malignant-like methylation characteristics. Our findings indicate striking similarities between SBOT and LGSC methylomes, supporting a common origin and the view that LGSC may arise from SBOT. A subgroup of SBOTs can be classified into tumors with a benign- or a malignant-like methylation profile that may help in identifying tumors more likely to progress into LGSCs.

Diagnosis, treatment, and follow-up of borderline ovarian tumors

Borderline ovarian tumors represent a heterogeneous group of noninvasive tumors of uncertain malignant potential with characteristic histology. They occur in younger women, are present at an early stage, and have a favorable prognosis, but symptomatic recurrence and death may be found as long as 20 years after therapy in some patients. The molecular changes in borderline ovarian tumors indicate linkage of this disease to type I ovarian tumors (low-grade ovarian carcinomas). The pathological stage of disease and subclassification of extraovarian disease into invasive and noninvasive implants, together with the presence of postoperative macroscopic residual disease, appear to be the major predictor of recurrence and survival. However, it should be emphasized that the most important negative prognostic factor for recurrence is just the use of conservative surgery, but without any impact on patient survival because most recurrent diseases are of the borderline type-easily curable and with an excellent prognosis. Borderline tumors are difficult masses to correctly preoperatively diagnose using imaging methods because their macroscopic features may overlap with invasive and benign ovarian tumors. Over the past several decades, surgical therapy has shifted from a radical approach to more conservative treatment; however, oncologic safety must always be balanced. Follow-up is essential using routine ultrasound imaging, with special attention paid to the remaining ovary in conservatively treated patients. Current literature on this topic leads to a number of controversies that will be discussed thoroughly in this article, with the aim to provide recommendations for the clinical management of these patients.

EGF-induced EMT and invasiveness in serous borderline ovarian tumor cells: a possible step in the transition to low-grade serous carcinoma cells?

In high-grade ovarian cancer cultures, it has been shown that epidermal growth factor (EGF) induces cell invasion by activating an epithelial-mesenchymal transition (EMT). However, the effect of EGF on serous borderline ovarian tumors (SBOT) and low-grade serous carcinomas (LGC) cell invasion remains unknown. Here, we show that EGF receptor (EGFR) was expressed, that EGF treatment increased cell migration and invasion in two cultured SBOT cell lines, SBOT3.1 and SV40 large T antigen-infected SBOT cells (SBOT4-LT), and in two cultured LGC cell lines, MPSC1 and SV40 LT/ST-immortalized LGC cells (ILGC). However, EGF induced down-regulation of E-cadherin and concurrent up-regulation of N-cadherin in SBOT cells but not in LGC cells. In SBOT cells, the expression of the transcriptional repressors of E-cadherin, Snail, Slug and ZEB1 were increased by EGF treatment. Treatment with EGF led to the activation of the downstream ERK1/2 and PI3K/Akt. The MEK1 inhibitor PD98059 diminished the EGF-induced cadherin switch and the up-regulation of Snail, Slug and ZEB1 and the EGF-mediated increase in SBOT cell migration and invasion. The PI3K inhibitor LY294002 had similar effects, but it could not block the EGF-induced up-regulation of N-cadherin and ZEB1. This study demonstrates that EGF induces SBOT cell migration and invasion by activating EMT, which involves the activation of the ERK1/2 and PI3K/Akt pathways and, subsequently, Snail, Slug and ZEB1 expression. Moreover, our results suggest that there are EMT-independent mechanisms that mediate the EGF-induced LGC cell migration and invasion.

Xenograft and transgenic mouse models of epithelial ovarian cancer and non-invasive imaging modalities to monitor ovarian tumor growth in situ: applications in evaluating novel therapeutic agents

Epithelial ovarian cancer (EOC) is the most commonly fatal gynecologic malignancy in developed countries. Most EOC patients are diagnosed at an advanced stage when disease has spread beyond the ovary. While many patients initially respond to surgery and chemotherapy, the long-term prognosis is generally unfavorable, with recurrence and development of drug-resistant disease. There is a critical need to identify new therapeutic agents that prolong disease-free intervals and effectively manage recurrent disease. Murine models of ovarian carcinoma are excellent models to study tumor biology in the search for new treatments for EOC. Described in this unit are methods for establishing xenograft or allograft models of EOC using ovarian carcinoma cell lines, in vivo imaging strategies for detection and quantification of EOC in transgenic and in xenograft/allograft models, and procedures for necropsy and pathological evaluation of experimental animals.

Improved classification of epithelial ovarian cancer: results of 3 danish cohorts

OBJECTIVE

An increasing body of evidence has suggested that epithelial ovarian cancer (EOC) patients can broadly be divided into 2 groups on the basis of histopathologic parameters and molecular profiles. Type 1 tumors are slow-growing tumors with inherent mutations such as KRAS or BRAF mutations, whereas type 2 tumors are more rapidly growing tumors of which many contain TP53 mutations. In the present study, we performed a comprehensive study in a large Danish material to evaluate the clinical importance.

MATERIALS AND METHODS

A total of 512 tissue samples were included (430 EOCs, 34 borderline, 28 benign tumors, and 20 normal ovaries). KRAS mutations (codon 12/13) and BRAF codon 600 mutations were analyzed from formalin-fixed paraffin-embedded tissue by ARMS qPCR. p53 expression was examined by immunohistochemistry.

RESULTS

Of the EOC patients, 25% had histopathologically classified type 1 tumors, and of these, 44% were either KRAS or BRAF mutated. Of patients with histopathologic type 2 tumors, 66% showed p53 protein overexpression, whereas 4 (1.5%) patients contained a KRAS mutation. In a univariate survival analysis, a large difference in survival was seen between patients with type 1 and type 2 tumors. Patients with type histologic 2 tumors had significantly worse survival compared with patients with type 1 tumors (P < 10). International Federation of Gynecology and Obstetrics (FIGO) stage, tumor grade, residual tumor, and KRAS/BRAF mutation were independent predictors of overall survival in the multivariate analysis. Patients with KRAS/BRAF mutated carcinomas showed independent decreased overall survival with a hazard ratio of 2.01 (95% confidence interval, 1.13-3.57; P = 0.018).

CONCLUSIONS

KRAS/BRAF mutations are with very few exceptions constrained to patients with histopathologic type 1 tumors, whereas p53 overexpression is very frequent in type 2 tumors. KRAS/BRAF mutations had independent prognostic importance. The classification presented here should have a major therapeutic implication and serve as a hallmark of future clinical trials.

Loss of ARID1A expression is related to shorter progression-free survival and chemoresistance in ovarian clear cell carcinoma

Recently, the ARID1A gene has been identified as a novel tumor suppressor in ovarian clear cell carcinoma. The prognostic significance of the loss of ARID1A expression is not known. The current study was designed to evaluate whether ARID1A was a prognostic factor for progression, survival, and chemoresistance in ovarian clear cell carcinoma. A total of 60 patients, who were surgically treated for primary ovarian clear cell adenocarcinoma, were enrolled. Surgical specimens were examined for ARID1A protein expression by immunohistochemistry. The correlations between the loss of ARID1A expression and clinicopathological characteristics, prognosis, and chemosensitivity were investigated. Loss of ARID1A expression was identified in 9 (15.0%) of 60 ovarian clear cell carcinoma samples. Loss of ARID1A staining intensity (0+) was more frequently found in cells of clear cell carcinomas than in high-grade serous carcinomas (P<0.01). Loss of ARID1A expression was significantly correlated with advanced FIGO stage and high CA125 levels (P=0.02, 0.01). There were no significant correlations between loss of ARID1A expression and patient age, status of residual tumor, Ki-67 labeling index, or the status of endometriosis. Loss of ARID1A correlated with shorter progression-free survival of patients with clear cell carcinomas treated with platinum-based chemotherapy (P<0.01). Loss of ARID1A expression tended to correlate with shorter overall survival in patients with ovarian clear cell carcinomas treated with platinum-based chemotherapy. When data were stratified for the multivariate analysis, only the loss of ARID1A expression remained a significant (P=0.03) predictor of reduced progression-free survival. Of the 60 patients with ovarian clear cell carcinomas, 14 patients had measurable residual tumor after primary cytoreductive surgery. Tumors with loss of ARID1A expression were more likely to be chemoresistant than tumors with positive ARID1A expression (100.0 vs 40.0%, P=0.04). This study demonstrates that loss of ARID1A in ovarian clear cell carcinoma is a negative prognostic factor in patients treated with platinum-based chemotherapy. Measurement of ARID1A expression may be a method to predict resistance to platinum-based chemotherapy in patients with ovarian clear cell carcinoma.

Ovarian Cancer Is an Imported Disease: Fact or Fiction?

The cell of origin of ovarian cancer has been long debated. The current paradigm is that epithelial ovarian cancer (EOC) arises from the ovarian surface epithelium (OSE). OSE is composed of flat, nondescript cells more closely resembling the mesothelium lining the peritoneal cavity, with which it is continuous, rather than the various histologic types of ovarian carcinoma (serous, endometrioid, and clear cell carcinoma), which have a Müllerian phenotype. Accordingly, it has been argued that the OSE undergoes a process termed "metaplasia" to account for this profound morphologic transformation. Recent molecular and clinicopathologic studies not only have failed to support this hypothesis but also have provided evidence that EOC stems from Müllerian-derived extraovarian cells that involve the ovary secondarily, thereby calling into question the very existence of primary EOC. This new model of ovarian carcinogenesis proposes that fallopian tube epithelium (benign or malignant) implants on the ovary to give rise to both high-grade and low-grade serous carcinomas, and that endometrial tissue implants on the ovary and produces endometriosis, which can undergo malignant transformation into endometrioid and clear cell carcinoma. Thus, ultimately EOC is not ovarian in origin but rather is secondary, and it is logical to conclude that the only true primary ovarian neoplasms are germ cell and gonadal stromal tumors analogous to tumors in the testis. If this new model is confirmed, it has profound implications for the early detection and treatment of "ovarian cancer."

Prognostic significance of L1CAM in ovarian cancer and its role in constitutive NF-κB activation

BACKGROUND

Overexpression of L1-cell adhesion molecule (L1CAM) has been observed for various carcinomas and correlates with poor prognosis and late-stage disease. In vitro, L1CAM enhances proliferation, cell migration, adhesion and chemoresistance. We tested L1CAM and interleukin-1 beta (IL-1β) expression in tumor samples and ascitic fluid from ovarian carcinoma patients to examine its role as a prognostic marker.

PATIENTS AND METHODS

We investigated tumor samples and ascitic fluid from 232 serous ovarian carcinoma patients for L1CAM by enzyme-linked immunosorbent assay. L1CAM expression was correlated with pathoclinical parameters and patients' outcome. IL-1β levels were measured in tumor cell lysates. Ovarian cancer cell lines were analyzed for the contribution of L1CAM to IL-1β production and nuclear factor 'kappa-light-chain-enhancer' of activated B-cells (NF-κB) activation.

RESULTS

We observed that L1CAM-expressing tumors show a highly invasive phenotype associated with restricted tumor resectability at primary debulking surgery and increased lymphogenic spread. Soluble L1CAM proved to be a marker for poor progression-free survival and chemoresistance. In ovarian carcinoma cell lines, the specific knock-down of L1CAM reduces IL-1β expression and NF-κB activity.

CONCLUSIONS

L1CAM expression contributes to the invasive and metastatic phenotype of serous ovarian carcinoma. L1CAM expression and shedding in the tumor microenvironment could contribute to enhanced invasion and tumor progression through increased IL-1β production and NF-κB activation.

Ovarian cancer: opportunity for targeted therapy

Ovarian cancer is a common cause of cancer mortality in women with limited treatment effectiveness in advanced stages. The limitation to treatment is largely the result of high rates of cancer recurrence despite chemotherapy and eventual resistance to existing chemotherapeutic agents. The objective of this paper is to review current concepts of ovarian carcinogenesis. We will review existing hypotheses of tumor origin from ovarian epithelial cells, Fallopian tube, and endometrium. We will also review the molecular pathogenesis of ovarian cancer which results in two specific pathways of carcinogenesis: (1) type I low-grade tumor and (2) type II high-grade tumor. Improved understanding of the molecular basis of ovarian carcinogenesis has opened new opportunities for targeted therapy. This paper will also review these potential therapeutic targets and will explore new agents that are currently being investigated.

Low-grade serous carcinomas of the ovary contain very few point mutations

It has been well established that ovarian low-grade and high-grade serous carcinomas are fundamentally different types of tumours. While the molecular genetic features of ovarian high-grade serous carcinomas are now well known, the pathogenesis of low-grade serous carcinomas, apart from the recognition of frequent somatic mutations involving KRAS and BRAF, is largely unknown. In order to comprehensively analyse somatic mutations in low-grade serous carcinomas, we applied exome sequencing to the DNA of eight samples of affinity-purified, low-grade, serous carcinomas. A remarkably small number of mutations were identified in seven of these tumours: a total of 70 somatic mutations in 64 genes. The eighth case displayed mixed serous and endometrioid features and a mutator phenotype with 783 somatic mutations, including a nonsense mutation in the mismatch repair gene, MSH2. We validated representative mutations in an additional nine low-grade serous carcinomas and 10 serous borderline tumours, the precursors of ovarian low-grade, serous carcinomas. Overall, the genes showing the most frequent mutations were BRAF and KRAS, occurring in 10 (38%) and 5 (19%) of 27 low-grade tumours, respectively. Except for a single case with a PIK3CA mutation, other mutations identified in the discovery set were not detected in the validation set of specimens. Our mutational analysis demonstrates that point mutations are much less common in low-grade serous tumours of the ovary than in other adult tumours, a finding with interesting scientific and clinical implications.

Meta-analysis of gene expression profiles associated with histological classification and survival in 829 ovarian cancer samples

Transcriptomic analysis of global gene expression in ovarian carcinoma can identify dysregulated genes capable to serve as molecular markers for histology subtypes and survival. The aim of our study was to validate previous candidate signatures in an independent setting and to identify single genes capable to serve as biomarkers for ovarian cancer progression. As several datasets are available in the GEO today, we were able to perform a true meta-analysis. First, 829 samples (11 datasets) were downloaded, and the predictive power of 16 previously published gene sets was assessed. Of these, eight were capable to discriminate histology subtypes, and none was capable to predict survival. To overcome the differences in previous studies, we used the 829 samples to identify new predictors. Then, we collected 64 ovarian cancer samples (median relapse-free survival 24.5 months) and performed TaqMan Real Time Polimerase Chain Reaction (RT-PCR) analysis for the best 40 genes associated with histology subtypes and survival. Over 90% of subtype-associated genes were confirmed. Overall survival was effectively predicted by hormone receptors (PGR and ESR2) and by TSPAN8. Relapse-free survival was predicted by MAPT and SNCG. In summary, we successfully validated several gene sets in a meta-analysis in large datasets of ovarian samples. Additionally, several individual genes identified were validated in a clinical cohort.

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

Background:

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

Methods:

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

Results:

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

Conclusion:

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

Endometriosis and ovarian cancer: a review of clinical, pathologic, and molecular aspects

Endometriosis is a chronic disease that affects millions of reproductive-age women. Despite the destructive and invasive nature of endometrioses, most cases are perpetually benign or eventually regress; however, atypical endometriosis is a precursor lesion and can lead to certain types of ovarian cancer. Endometriosis induced inflammation and auto- and paracrine production of sex steroid hormones contribute to ovarian tumorigenesis. These changes provide microenvironment necessary to accumulate enough genetic alterations for endometriosis associated malignant transformation. It takes years for endometriosis to undergo the pathophysiological progression that begins with atypical epithelial proliferation (atypical endometriosis and metaplasia), and then is followed by the formation of well-defined borderline tumors, and finally culminates in fully malignant ovarian cancer. This study is a review of the natural history of endometriosis and the role of microenvironments that favor the accumulation of genetic alterations and endometriosis-associated ovarian cancer progression.

Histologic, molecular, and cytogenetic features of ovarian cancers: implications for diagnosis and treatment

Ovarian epithelial carcinoma (OEC), the most common ovarian malignancy, is a heterogeneous disease with several histologic subtypes that show characteristic cytogenetic features, molecular signatures, oncologic signaling pathways, and clinical-biologic behavior. Recent advances in histopathology and cytogenetics have provided insights into pathophysiologic features and natural history of OECs. Several studies have shown that high- or low-grade serous, endometrioid, and clear cell carcinomas are characterized by mutations involving the TP53, K-ras/BRAF, CTNNB1, and PIK3CA genes, respectively. High-grade serous carcinomas, the most common subtype, often manifest with early transcoelomic spread of disease beyond the ovaries, whereas low-grade serous and mucinous carcinomas commonly manifest with early-stage disease, with a resultant excellent prognosis. On the basis of pathogenetic mechanisms, recent findings suggest a dualistic model of ovarian carcinogenesis consisting of types I and II. Type I (low-grade serous, mucinous, and endometrioid) cancers commonly arise from well-described, genetically stable precursor lesions (usually borderline tumors); manifest as large adnexal masses with early-stage disease; and have a relatively indolent clinical course, with an overall good prognosis. In contrast, type II carcinomas (high-grade serous, endometrioid, mixed, and undifferentiated variants) originate de novo from the adnexal epithelia, often demonstrate chromosomal instability, and have aggressive biologic behavior. Better knowledge of hereditary ovarian cancer syndromes and associated cytogenetic abnormalities has led to increased interest in novel biomarkers and molecular therapeutics. Genetic changes, pathologic features, imaging findings, and natural histories of a variety of histologic subtypes of OEC are discussed in this article.

Prognostic role of CIP2A expression in serous ovarian cancer

Background:

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein expressed in several solid cancers. Our purpose was to study its role in serous ovarian cancer patients, and the association to clinicopathological variables and molecular markers.

Methods:

We collected retrospectively 562 consecutive serous ovarian cancer patients treated at the Helsinki University Central Hospital. We stained tumour tissue microarrays for CIP2A by immunohistochemistry and constructed survival curves according to the Kaplan–Meier method. Associations to clinicopathological and molecular markers were assessed by the χ²-test.

Results:

We found strong cytoplasmic CIP2A immunoreactivity in 212 (40.4%) specimens, weak positivity in 222 (42.4%) specimens, and negative in 90 (17.2%). Immunopositive CIP2A expression was associated with high grade (P<0.0001), advanced stage (P=0.0005), and aneuploidy (P=0.001, χ²-test). Cancerous inhibitor of protein phosphatase 2A overexpression was also associated with EGFR protein expression (P=0.006) and EGFR amplification (P=0.043). Strong cytoplasmic CIP2A immunopositivity predicted poor outcome in ovarian cancer patients (P<0.0001, log-rank test).

Conclusion:

Our results show that CIP2A associates with reduced survival and parameters associated with high grade in ovarian cancer patients, and may thus be one of the factors that identify aggressive subtype (type II) of this disease.

Telomere length in different histologic types of ovarian carcinoma with emphasis on clear cell carcinoma

Ovarian carcinoma is composed of a heterogeneous group of tumors with distinct clinico-pathological and molecular features. Alteration of telomerase activity has been reported in ovarian tumors but the pattern of telomere length in their specific histological subtypes has not been reported. In this study, we performed quantitative telomere fluorescence in situ hybridization on a total of 219 ovarian carcinomas including 106 high-grade serous carcinomas, 26 low-grade serous carcinomas, 56 clear cell carcinomas and 31 low-grade endometrioid carcinomas. The mean relative telomere length of carcinoma to stromal cells was calculated as a telomere index. This index was significantly higher in clear cell carcinoma compared with the other histologic types (P=0.007). Overall there was no association between the telomere index and mortality, but when stratified by histologic types, the hazard ratio for death among women with clear cell carcinoma with a telomere index >1 was significantly increased at 4.93 (95% CI 1.64-14.86, P=0.005) when compared with those with a telomere index ≤1. In conclusion, our results provide new evidence that telomere length significantly differs by histologic type in ovarian carcinoma. Specifically, clear cell carcinomas have longer mean relative telomere lengths compared with the other histologic types and longer telomeres in clear cell carcinoma are associated with increased mortality suggesting that aberrations in telomere length may have an important role in the development and progression of this neoplasm.

The anterior gradient homolog 3 (AGR3) gene is associated with differentiation and survival in ovarian cancer

Low-grade (LG) serous ovarian carcinoma is believed to arise from serous borderline ovarian tumors; yet the progression from serous borderline tumors to LG serous ovarian carcinoma remains poorly understood. The purpose of this study was to identify differentially expressed genes between the 2 groups. Expression profiles were generated from 6 human ovarian surface epithelia, 8 serous borderline ovarian tumors (SBOTs), 13 LG serous ovarian carcinomas, and 24 high-grade (HG) serous ovarian carcinomas. The anterior gradient homolog 3 (AGR3) gene was found to be highly upregulated in serous borderline ovarian tumors. This finding was validated by real-time quantitative reverse-transcription polymerase chain reaction, Western blotting, and immunohistochemistry. Anti-AGR3 immunohistochemistry was performed on an additional 56 LG and 103 HG tissues, and the results were correlated with clinical data. Expression profiling determined that 1254 genes were differentially expressed (P<0.005) among SBOT, LG, and HG tumors. SBOTs exhibited robust positive staining for AGR3, with a lower percentage of tumor cells stained in LG and HG. Immunofluorescence staining indicated that AGR3 expression was limited to ciliated cells. Tumor samples with a high percentage (>10%) of AGR3 positively stained tumor cells were associated with improved longer median survival in both the LG (P=0.013) and HG (P=0.008) serous ovarian carcinoma groups. The progression of SBOT to LG serous ovarian carcinoma may involve the dedifferentiation of ciliated cells. AGR3 could serve as a prognostic marker for survival in patients with LG and HG serous ovarian carcinomas.

The insulin-like growth factor 1 pathway is a potential therapeutic target for low-grade serous ovarian carcinoma

OBJECTIVE

To validate the overexpression of insulin-like growth factor 1 (IGF-1) and its receptor (IGF-1R) in low-grade serous ovarian carcinoma (SOC), and to investigate whether the IGF-1 pathway is a potential therapeutic target for low-grade SOC.

METHODS

Gene expression profiling was performed on serous borderline ovarian tumors (SBOTs) and low-grade SOC, and overexpression of IGF-1 in low-grade SOC was validated by RT-PCR and immunohistochemistry. The effect of exogenous IGF-1 on cell proliferation was determined in cell lines by cell proliferation assays, cell migration assays, and Western blot. Signaling pathways downstream of IGF-1 and the effects of the AKT inhibitor MK-2206 were investigated by Western blot analysis and by generating IGF-1R short hairpin RNA stable knockdown cell lines. Low- and high-grade cell lines were treated with the dual IGF-1R- and insulin receptor-directed tyrosine kinase inhibitor OSI-906, and cellular proliferation was measured.

RESULTS

mRNA analysis and immunostaining revealed significantly higher IGF-1 expression in low-grade SOCs than in SBOTs or high-grade SOCs. In response to exogenous treatment with IGF-1, low-grade cell lines exhibited more intense upregulation of phosphorylated AKT than did high-grade cell lines, an effect that was diminished with IGF-1R knockdown and MK-2206 treatment. Low-grade SOC cell lines were more sensitive to growth inhibition with OSI-906 than were high-grade cell lines.

CONCLUSIONS

IGF-1 is overexpressed in low-grade SOCs compared with SBOTs and high-grade SOCs. Additionally, low-grade SOC cell lines were more responsive to IGF-1 stimulation and IGF-1R inhibition than were high-grade lines. The IGF-1 pathway is therefore a potential therapeutic target in low-grade SOC.