PTEN mutation, expression and LOH at its locus in ovarian carcinomas. Relation to TP53, K-RAS and BRCA1 mutations

New insights about endometriosis-associated ovarian cancer: pathogenesis, risk factors, prediction and diagnosis and treatment

Previous studies have shown that the risk of malignant transformation of endometriosis in premenopausal women is approximately 1%, significantly impacting the overall well-being and quality of life of affected women. Presently, the diagnostic gold standard for endometriosis-associated ovarian cancer (EAOC) continues to be invasive laparoscopy followed by histological examination. However, the application of this technique is limited due to its high cost, highlighting the importance of identifying a non-invasive diagnostic approach. Therefore, there is a critical need to explore non-invasive diagnostic methods to improve diagnostic precision and optimize clinical outcomes for patients. This review presents a comprehensive survey of the current progress in comprehending the pathogenesis of malignant transformation in endometriosis. Furthermore, it examines the most recent research discoveries concerning the diagnosis of EAOC and emphasizes potential targets for therapeutic intervention. The ultimate objective is to improve prevention, early detection, precise diagnosis, and treatment approaches, thereby optimizing the clinical outcomes for patients.

Comprehensive review of CRISPR-based gene editing: mechanisms, challenges, and applications in cancer therapy

The CRISPR system is a revolutionary genome editing tool that has the potential to revolutionize the field of cancer research and therapy. The ability to precisely target and edit specific genetic mutations that drive the growth and spread of tumors has opened up new possibilities for the development of more effective and personalized cancer treatments. In this review, we will discuss the different CRISPR-based strategies that have been proposed for cancer therapy, including inactivating genes that drive tumor growth, enhancing the immune response to cancer cells, repairing genetic mutations that cause cancer, and delivering cancer-killing molecules directly to tumor cells. We will also summarize the current state of preclinical studies and clinical trials of CRISPR-based cancer therapy, highlighting the most promising results and the challenges that still need to be overcome. Safety and delivery are also important challenges for CRISPR-based cancer therapy to become a viable clinical option. We will discuss the challenges and limitations that need to be overcome, such as off-target effects, safety, and delivery to the tumor site. Finally, we will provide an overview of the current challenges and opportunities in the field of CRISPR-based cancer therapy and discuss future directions for research and development. The CRISPR system has the potential to change the landscape of cancer research, and this review aims to provide an overview of the current state of the field and the challenges that need to be overcome to realize this potential.

Landscape of somatic mutated genes and inherited susceptibility genes in gynecological cancer

Traditionally, gynecological cancers have been classified based on histology. Since remarkable advancements in next-generation sequencing technology have enabled the exploration of somatic mutations in various cancer types, comprehensive sequencing efforts have revealed the genomic landscapes of some common forms of human cancer. The genomic features of various gynecological malignancies have been reported by several studies of large-scale genomic cohorts, including The Cancer Genome Atlas. Although recent comprehensive genomic profiling tests, which can detect hundreds of genetic mutations at a time from cancer tissues or blood samples, have been increasingly used as diagnostic clinical biomarkers and in therapeutic management decisions, germline pathogenic variants associated with hereditary cancers can also be detected using this test. Gynecological cancers are closely related to genetic factors, with approximately 5% of endometrial cancer cases and 20% of ovarian cancer cases being caused by germline pathogenic variants. Hereditary breast and ovarian cancer syndrome and Lynch syndrome are the two major cancer susceptibility syndromes among gynecological cancers. In addition, several other hereditary syndromes have been reported to be associated with gynecological cancers. In this review, we highlight the genes for somatic mutation and germline pathogenic variants commonly seen in gynecological cancers. We first describe the relationship between clinicopathological attributes and somatic mutated genes. Subsequently, we discuss the characteristics and clinical management of inherited cancer syndromes resulting from pathogenic germline variants in gynecological malignancies.

PTEN, PTENP1, microRNAs, and ceRNA Networks: Precision Targeting in Cancer Therapeutics

The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a well characterised tumour suppressor, playing a critical role in the maintenance of fundamental cellular processes including cell proliferation, migration, metabolism, and survival. Subtle decreases in cellular levels of PTEN result in the development and progression of cancer, hence there is tight regulation of the expression, activity, and cellular half-life of PTEN at the transcriptional, post-transcriptional, and post-translational levels. PTENP1, the processed pseudogene of PTEN, is an important transcriptional and post-transcriptional regulator of PTEN. PTENP1 expression produces sense and antisense transcripts modulating PTEN expression, in conjunction with miRNAs. Due to the high sequence similarity between PTEN and the PTENP1 sense transcript, the transcripts possess common miRNA binding sites with the potential for PTENP1 to compete for the binding, or 'sponging', of miRNAs that would otherwise target the PTEN transcript. PTENP1 therefore acts as a competitive endogenous RNA (ceRNA), competing with PTEN for the binding of specific miRNAs to alter the abundance of PTEN. Transcription from the antisense strand produces two functionally independent isoforms (PTENP1-AS-α and PTENP1-AS-β), which can regulate PTEN transcription. In this review, we provide an overview of the post-transcriptional regulation of PTEN through interaction with its pseudogene, the cellular miRNA milieu and operation of the ceRNA network. Furthermore, its importance in maintaining cellular integrity and how disruption of this PTEN-miRNA-PTENP1 axis may lead to cancer but also provide novel therapeutic opportunities, is discussed. Precision targeting of PTENP1-miRNA mediated regulation of PTEN may present as a viable alternative therapy.

Identification and clinical significance of somatic oncogenic mutations in epithelial ovarian cancer

OBJECTIVE

Epithelial ovarian cancer (EOC) is a heterogeneous disease with diverse clinicopathological features and behaviors, and its heterogeneity may be concerned with the accumulation of multiple somatic oncogenic mutations. The major goals of this study are to systematically perform the comprehensive mutational profiling in EOC patients, and investigate the associations between somatic mutations and clinicopathological characteristics.

METHODS

A total of 80 surgical specimens were obtained from EOC patients who had previously undergone primary debulking surgery, and genomic DNAs were extracted from fresh-frozen tissues. We investigated mutational status in hot spot regions of 50 cancer-related genes by targeted next-generation sequencing using an Ion AmpliSeq Cancer Hotspot Panel v2 Kit.

RESULTS

Validated mutations were detected in 66 of the 80 tumors (82.5%). The five most frequently mutated genes were TP53 (43.8%), PIK3CA (27.5%), KRAS (23.8%), PTEN (10%) and CTNNB1 (10%). PTEN and CTNNB1 mutations were associated with younger age. PIK3CA1, KRAS and CTNNB1 mutations were observed in early-stage, whereas TP53 mutations were more common in advanced stage. Significant associations were observed between TP53 mutation and serous carcinoma, and between KRAS mutation and mucinous carcinoma. Both PIK3CA mutation and CTNNB1 mutation were also significantly associated with endometrioid and clear cell carcinoma. The patients with PIK3CA and KRAS mutations were significantly associated with favorable progression free survival (PFS). In particular, PIK3CA mutations had more significant associations with favorable PFS than PIK3CA wild-type in the endometrioid subtype (P = 0.012). Patients with mutations only in TP53 were significantly associated with worse PFS.

CONCLUSION

EOCs were heterogeneous at the genomic level and harbored somatic oncogenic mutations. Our molecular profiling may have the potential for becoming a novel stratification within histological subtypes of EOC. Further studies are needed to define molecular classification for improved clinical outcomes and treatment of EOC patients in future.

Precise Immunodetection of PTEN Protein in Human Neoplasia

PTEN is a major tumor-suppressor protein whose expression and biological activity are frequently diminished in sporadic or inherited cancers. PTEN gene deletion or loss-of-function mutations favor tumor cell growth and are commonly found in clinical practice. In addition, diminished PTEN protein expression is also frequently observed in tumor samples from cancer patients in the absence of PTEN gene alterations. This makes PTEN protein levels a potential biomarker parameter in clinical oncology, which can guide therapeutic decisions. The specific detection of PTEN protein can be achieved by using highly defined anti-PTEN monoclonal antibodies (mAbs), characterized with precision in terms of sensitivity for the detection technique, specificity for PTEN binding, and constraints of epitope recognition. This is especially relevant taking into consideration that PTEN is highly targeted by mutations and posttranslational modifications, and different PTEN protein isoforms exist. The precise characterization of anti-PTEN mAb reactivity is an important step in the validation of these reagents as diagnostic and prognostic tools in clinical oncology, including their routine use in analytical immunohistochemistry (IHC). Here, we review the current status on the use of well-defined anti-PTEN mAbs for PTEN immunodetection in the clinical context and discuss their potential usefulness and limitations for a more precise cancer diagnosis and patient benefit.

Metachronous ovarian endometrioid carcinomas in a patient with a PTEN variant: case report of incidentally detected Cowden syndrome

Background

Somatic PTEN mutation occurs in a proportion of ovarian endometrioid carcinomas. However, these cancers have seldom been reported in diseases associated with germline PTEN variants, such as Cowden syndrome (CS).

Case presentation

The present case was a 39-year-old woman with a left ovarian carcinoma who demonstrated a germline splice variant of PTEN (c.1026 + 1G > T) following genome-wide whole exome sequencing of her germline DNA. Histology of her resected tumor revealed endometrioid carcinoma of the same type as a right ovarian cancer resected eight years previously. These tumors showed null immunostaining for PTEN. She was genetically diagnosed with CS. Despite her clinical examinations had demonstrated several characteristic findings of CS, including mammary fibroma, esophageal and skin papilloma, colonic hamartoma, uterine myoma, and lipoma, the clinicians could not approach this diagnosis.

Conclusion

Ovarian endometrioid carcinoma is generally thought to develop from endometrial tissue menstruated from the uterus and implanted on the ovary. To date, ovarian cancers have not been listed as CS-related cancers; however, ovarian endometrioid cancer can have a potential association with CS in endometriosis cases.

Mechanisms of PTEN loss in cancer: It's all about diversity

PTEN is a phosphatase which metabolises PIP₃, the lipid product of PI 3-Kinase, directly opposing the activation of the oncogenic PI3K/AKT/mTOR signalling network. Accordingly, loss of function of the PTEN tumour suppressor is one of the most common events observed in many types of cancer. Although the mechanisms by which PTEN function is disrupted are diverse, the most frequently observed events are deletion of a single gene copy of PTEN and gene silencing, usually observed in tumours with little or no PTEN protein detectable by immunohistochemistry. Accordingly, with the exceptions of glioblastoma and endometrial cancer, mutations of the PTEN coding sequence are uncommon (<10%) in most types of cancer. Here we review the data relating to PTEN loss in seven common tumour types and discuss mechanisms of PTEN regulation, some of which appear to contribute to reduced PTEN protein levels in cancers.

Comprehensive Clinicopathologic and Updated Immunohistochemical Characterization of Primary Ovarian Mucinous Carcinoma

The distinction of primary mucinous ovarian carcinoma (PMOC) from other primaries or secondaries is essential for selecting therapeutic options and prognostication. We aimed to characterize the immunohistochemical profile of 36 PMOCs using an extended immunohistochemical panel, with clinicopathologic features and outcome. PAX8 was negative in 30 (83.3%), and SATB2 was negative in 32/35. HNF1B, AMACR, and napsin-A were detected in 33 (91.7%), 35 (97.2%), and 0 (0%), respectively. MMR proteins and ARID1A were retained in 100%; PTEN was lost in 4 (11.1%). P53 was aberrant in 10 (27.8%); none overexpressed p16. HER2 was positive in 6/35 (17.1%). Most PMOCs had a favorable outcome. However, recurrence is usually fatal. The typical tumor profile was CK7+, CK20+/-, CDX2+/-, PAX8-, ER-, PgR-, and SATB2-. HER2 positivity suggests a possible target for therapy in advanced disease.

First application of the Automated QUantitative Analysis (AQUA) technique to quantify PTEN protein expression in ovarian cancer: A correlative study of NCIC CTG OV.16

BACKGROUND

Platinum resistance is a dominant cause of poor outcomes in advanced ovarian cancer (OC). A mechanism of platinum resistance is the inhibition of apoptosis through phosphatidylinositol 3 kinase (PI3K) pathway activation. The role of phosphatase and tensin homolog (PTEN), a negative regulator of this pathway, as a tumor biomarker is unclear. Quantitative analysis of PTEN expression as an alternative to immunohistochemistry has not been considered.

PATIENTS AND METHODS

In 238 patient tumors from the NCIC-CTG trial OV.16, PTEN protein expression was quantified by Automated QUantitative Analysis (AQUA). Cox model was used to study the association between PTEN expression and clinical outcomes using a minimum p-value approach in univariate analysis. Multivariate analysis was used to adjust for clinical and pathological parameters.

RESULTS

PTEN scores (range 13.9-192.3) of the 202 samples that passed quality control were analyzed. In univariate analysis, there was a trend suggesting an association between PTEN expression by AQUA as a binary variable (low ≤61 vs high >61) and progression free survival (HR=0.77, p=0.083), and in multivariate analysis, this association approached significance (HR=0.74, p=0.059). The relationship between quantitative PTEN expression and PFS differed (p=0.01 for interaction) by the extent of surgical debulking (residual disease (RD) <1cm or ≥1cm), with a numerically superior PFS in patients with high PTEN (23.5 vs 14.9m) only when RD<1cm (p=0.19). There was no association between PTEN levels and overall survival.

CONCLUSIONS

AQUA is a novel method to measure PTEN expression. Further study of PTEN as a biomarker in OC is warranted.

High-Throughput Amplicon-Based Copy Number Detection of 11 Genes in Formalin-Fixed Paraffin-Embedded Ovarian Tumour Samples by MLPA-Seq

Whilst next generation sequencing can report point mutations in fixed tissue tumour samples reliably, the accurate determination of copy number is more challenging. The conventional Multiplex Ligation-dependent Probe Amplification (MLPA) assay is an effective tool for measurement of gene dosage, but is restricted to around 50 targets due to size resolution of the MLPA probes. By switching from a size-resolved format, to a sequence-resolved format we developed a scalable, high-throughput, quantitative assay. MLPA-seq is capable of detecting deletions, duplications, and amplifications in as little as 5ng of genomic DNA, including from formalin-fixed paraffin-embedded (FFPE) tumour samples. We show that this method can detect BRCA1, BRCA2, ERBB2 and CCNE1 copy number changes in DNA extracted from snap-frozen and FFPE tumour tissue, with 100% sensitivity and >99.5% specificity.

Histone deacetylases as new therapy targets for platinum-resistant epithelial ovarian cancer

Introduction

In developed countries, ovarian cancer is the fourth most common cancer in women. Due to the non-specific symptomatology associated with the disease many patients with ovarian cancer are diagnosed late, which leads to significantly poorer prognosis. Apart from surgery and radiotherapy, a substantial number of ovarian cancer patients will undergo chemotherapy and platinum based agents are the mainstream first-line therapy for this disease. Despite the initial efficacy of these therapies, many women relapse; therefore, strategies for second-line therapies are required. Regulation of DNA transcription is crucial for tumour progression, metastasis and chemoresistance which offers potential for novel drug targets.

Methods

We have reviewed the existing literature on the role of histone deacetylases, nuclear enzymes regulating gene transcription.

Results and conclusion

Analysis of available data suggests that a signifant proportion of drug resistance stems from abberant gene expression, therefore HDAC inhibitors are amongst the most promising therapeutic targets for cancer treatment. Together with genetic testing, they may have a potential to serve as base for patient-adapted therapies.

The Association between Endometriomas and Ovarian Cancer: Preventive Effect of Inhibiting Ovulation and Menstruation during Reproductive Life

Although endometriosis frequently involves multiple sites in the pelvis, malignancies associated with this disease are mostly confined to the ovaries, evolving from an endometrioma. Endometriomas present a 2-3-fold increased risk of transformation in clear-cell, endometrioid, and possibly low-grade serous ovarian cancers, but not in mucinous ovarian cancers. These last cancers are, in some aspects, different from the other epithelial ovarian cancers, as they do not appear to be decreased by the inhibition of ovulation and menstruation. The step by step process of transformation from typical endometrioma, through atypical endometrioma, finally to ovarian cancer seems mainly related to oxidative stress, inflammation, hyperestrogenism, and specific molecular alterations. Particularly, activation of oncogenic KRAS and PI3K pathways and inactivation of tumor suppressor genes PTEN and ARID1A are suggested as major pathogenic mechanisms for endometriosis associated clear-cell and endometrioid ovarian cancer. Both the risk for endometriomas and their associated ovarian cancers seems to be highly and similarly decreased by the inhibition of ovulation and retrograde menstruation, suggesting a common pathogenetic mechanism and common possible preventive strategies during reproductive life.

[Endometriosis-related ovarian tumors]

Endometriosis is a frequent gynecological disease of unknown etiology and pathogenesis. It affects the gynecological organs and the peritoneum with varying frequency and can lead to severe symptoms, mainly pain and to infertility. Despite the fact that causal therapy is not feasible diagnostic and therapeutic procedures are necessary in many cases. In a small percentage of cases endometriosis is associated with neoplastic disease and in some cases it might develop into a neoplasm via the stage of atypical endometriosis, notably in the ovaries. Tumors which are most frequently associated with endometriosis are endometrioid carcinoma, clear cell carcinoma, and low grade serous carcinoma. According to some authors tumors associated with endometriosis have a better prognosis than those without. Other tumors are Mullerian adenosarcoma, endometrioid stromal sarcoma, and seromucinous borderline tumor. In addition to the morphological findings more recent molecular findings serve to demonstrate the origin of the different types of carcinoma from endometriosis. In both endometrioid and clear cell carcinoma, loss of heterozygosity (LOH) can be found in different gene loci. Mutations in CTNNB1 (beta catenin), PTEN, KRAS and ARID1a genes have been demonstrated in endometrioid carcinoma. Cases of clear cell carcinoma have been characterized by mutations of ARID1a gene, PIK3CA and less frequently PPP2R1A and KRAS.

The promise and challenge of ovarian cancer models

The complexity and heterogeneity of ovarian cancer cases are difficult to reproduce in in vitro studies, which cannot adequately elucidate the molecular events involved in tumor initiation and disease metastasis. It has now become clear that, although the multiple histological subtypes of ovarian cancer are being treated with similar surgical and therapeutic approaches, they are in fact characterized by distinct phenotypes, cell of origin, and underlying key genetic and genomic alterations. Consequently, the development of more personalized treatment methodologies, which are aimed at improving patient care and prognosis, will greatly benefit from a better understanding of the key differences between various subtypes. To accomplish this, animal models of all histotypes need to be generated in order to provide accurate in vivo platforms for research and the testing of targeted treatments and immune therapies. Both genetically engineered mouse models (GEMMs) and xenograft models have the ability to further our understanding of key mechanisms facilitating tumorigenesis, and at the same time offer insight into enhanced imaging and treatment modalities. While genetic models may be better suited to examine oncogenic functions and interactions during tumorigenesis, patient-derived xenografts (PDXs) are likely a superior model to assess drug efficacy, especially in concurrent clinical trials, due to their similarity to the tumors from which they are derived. Genetic and avatar models possess great clinical utility and have both benefits and limitations. Additionally, the laying hen model, which spontaneously develops ovarian tumors, has inherent advantages for the study of epithelial ovarian cancer (EOC) and recent work champions this model especially when assessing chemoprevention strategies. While high-grade ovarian serous tumors are the most prevalent form of EOC, rarer ovarian cancer variants, such as small cell ovarian carcinoma of the hypercalcemic type and transitional cell carcinoma, or non-epithelial tumors, including germ cell tumors, will also benefit from the generation of improved models to advance our understanding of tumorigenic mechanisms and the development of selective therapeutic options.

Combined image and genomic analysis of high-grade serous ovarian cancer reveals PTEN loss as a common driver event and prognostic classifier

BACKGROUND

TP53 and BRCA1/2 mutations are the main drivers in high-grade serous ovarian carcinoma (HGSOC). We hypothesise that combining tissue phenotypes from image analysis of tumour sections with genomic profiles could reveal other significant driver events.

RESULTS

Automatic estimates of stromal content combined with genomic analysis of TCGA HGSOC tumours show that stroma strongly biases estimates of PTEN expression. Tumour-specific PTEN expression was tested in two independent cohorts using tissue microarrays containing 521 cases of HGSOC. PTEN loss or downregulation occurred in 77% of the first cohort by immunofluorescence and 52% of the validation group by immunohistochemistry, and is associated with worse survival in a multivariate Cox-regression model adjusted for study site, age, stage and grade. Reanalysis of TCGA data shows that hemizygous loss of PTEN is common (36%) and expression of PTEN and expression of androgen receptor are positively associated. Low androgen receptor expression was associated with reduced survival in data from TCGA and immunohistochemical analysis of the first cohort.

CONCLUSION

PTEN loss is a common event in HGSOC and defines a subgroup with significantly worse prognosis, suggesting the rational use of drugs to target PI3K and androgen receptor pathways for HGSOC. This work shows that integrative approaches combining tissue phenotypes from images with genomic analysis can resolve confounding effects of tissue heterogeneity and should be used to identify new drivers in other cancers.

The molecular background of mucinous carcinoma beyond MUC2

The increasing interest of the oncology community in tumour classification and prediction of outcome to targeted therapies has put emphasis on an improved identification of tumour types. Colorectal mucinous adenocarcinoma (MC) is a subtype that is characterized by the presence of abundant extracellular mucin that comprises at least 50% of the tumour volume and is found in 10–15% of colorectal cancer patients. MC development is poorly understood, however, the distinct clinical and pathological presentation of MC suggests a deviant development and molecular background. In this review we identify common molecular and genetic alterations in colorectal MC. MC is characterized by a high rate of MUC2 expression. Mutation rates in the therapeutically important RAS/RAF/MAPK and PI3K/AKT pathways are significantly higher in MC compared with non‐mucinous adenocarcinoma. Furthermore, mucinous adenocarcinoma shows higher rates of microsatellite instability and is more frequently of the CpG island methylator phenotype. Although the majority of MCs arise from the large intestine, this subtype also develops in other organs, such as the stomach, pancreas, biliary tract, ovary, breast and lung. We compared findings from colorectal MC with tumour characteristics of MCs from other organs. In these organs, MCs show different mutation rates in the RAS/RAF/MAPK and PI3K/AKT pathways as well, but a common mucinous pathway cannot be identified. Identification of conditions and molecular aberrations that are associated with MC generates insight into the aetiology of this subtype and improves understanding of resistance to therapies.

The role of the PTEN/PI3K/Akt pathway on prognosis in epithelial ovarian cancer: a meta-analysis

The PTEN/PI3K/Akt signaling pathway, a key player in mediating apoptosis, metabolism, cell proliferation, and cell growth, is frequently dysregulated in many cancers. However, the pathway's prognostic impact in epithelial ovarian cancer (EOC) is still inconsistent. We performed a meta-analysis based on individual study outcomes to more precisely evaluate its clinical significance in EOC patients. Methods. We searched all potentially relevant studies published between January 1, 1990, and March 1, 2013, that assessed the association between PTEN, PI3K, and Akt status and survival in EOC. Meta-analysis was performed using a fixed-effect or random-effects model as appropriate. We investigated the possibility of publication bias through a funnel plot and identified the heterogeneity by I(2) statistics. Results. Eleven eligible studies were analyzed for PTEN, 5 for PI3K, and 11 for pAkt. High PI3K and pAkt expression was associated with poor overall survival (OS; pooled adjusted hazard ratio [HR] = 1.44, 95% CI, 1.08-1.91 for PI3K; HR = 1.60, 95% CI, 1.26-2.04 for pAkt). In addition, both the meta-analyses of univariate and multivariate estimates showed that only high pAkt expression was significantly associated with poor progression-free survival (PFS; pooled unadjusted HR = 1.24, 95% CI, 1.10-1.39; pooled adjusted HR = 1.65, 95% CI, 1.07-2.55). Conclusion. Published studies suggest that high pAkt expression is significantly associated with poor OS and PFS in EOC patients, but currently available evidence is insufficient to recommend that PTEN, PI3K, or Akt be used as prognostic predictors in EOC in clinical practice.

TP53 mutations are common in all subtypes of epithelial ovarian cancer and occur concomitantly with KRAS mutations in the mucinous type

AIMS

Epithelial ovarian cancer (EOC) can be classified into four major types (serous, endometrioid, clear cell, mucinous). The prevalence of driver gene mutations in the different subtypes is controversial. High-grade serous carcinomas show frequent TP53 mutations, whereas KRAS and BRAF mutations are less common. In non-serous EOC, the relevance of these gene mutations remains to be elucidated.

METHODS

We investigated 142 formalin-fixed, paraffin-embedded EOC, including serous (n=63), endometrioid (n=29), clear cell (n=25), mucinous (n=14), and others (n=11) for mutations in TP53 exons 5-8, KRAS exons 2 and 3, and BRAF exon 15 by pyro-sequencing using the GS Junior 454 platform. The mutational status was correlated with clinicopathological features and patient overall survival.

RESULTS

We identified mutations in the coding region of TP53 in 51.4% (73/142), and of KRAS in 9.9% (14/142) but not of BRAF. TP53 mutations occurred frequently not only in high-grade serous carcinomas (58.7%), but also in mucinous (57%) and clear cell EOC (52%). TP53 mutations were associated with high-grade carcinomas (p=0.014), advanced FIGO stage (p=0.001), intraoperative residual disease >1cm (p=0.004), as well as poor overall survival (p=0.002). KRAS mutations were mainly identified in mucinous EOC (57%) and were concomitantly with TP53 mutations in five mucinous carcinomas (36%).

CONCLUSIONS

TP53 gene driver mutations are a common feature of all advanced ovarian cancer subtypes, whereas BRAF mutations seem to be a rare event in EOC. KRAS mutations with synchronous TP53 mutations occur predominantly in low-grade mucinous carcinomas, suggesting a specific molecular background of this ovarian cancer type.

p19(INK4d) mRNA and protein expression as new prognostic factors in ovarian cancer patients

p19(INK4d) (CDKN2D) is a negative regulator of the cell cycle. Little is known of its role in cancer development and prognosis. We aimed to evaluate the clinical significance of p19(INK4d) expression in ovarian carcinomas with respect to the TP53 accumulation status, as well as the frequency of CDKN2D mutations. p19(INK4d) and TP53 expression was evaluated immunohistochemically in 445 ovarian carcinomas: 246 patients were treated with platinum-cyclophosphamide (PC/PAC), while 199 were treated with taxane-platinum agents (TP). CDKN2D gene expression (mRNA) was examined in 106 carcinomas, while CDKN2D mutations in 68 tumors. Uni- and multivariate statistical analyses (logistic regression and the Cox proportional hazards model) were performed for patient groups divided according to the chemotherapeutic regimen administered, and in subgroups with and without TP53 accumulation. High p19(INK4d) expression increased the risk of death, but only in patients with the TP53-negative carcinomas (HR 1.61, P = 0.049 for PC/PAC-treated patients, HR 2.00, P = 0.015 for TP-treated patients). This result was confirmed by the mRNA analysis (HR 4.24, P = 0.001 for TP-treated group). High p19(INK4d) protein expression associated with adverse clinicopathological factors. We found no alterations in the CDKN2D gene; the c.90C>G (p.R30R; rs1968445) polymorphism was detected in 10% of tumors. Our results suggest that p19(INK4d) expression is a poor prognostic factor in ovarian cancer patients. Analyses of tumor groups according to the TP53 accumulation status facilitate the identification of cancer biomarkers.

Endometriosis-associated ovarian cancer: a review of pathogenesis

Endometriosis is classically defined as the presence of endometrial glands and stroma outside of the endometrial lining and uterine musculature. With an estimated frequency of 5%–10% among women of reproductive age, endometriosis is a common gynecologic disorder. While in itself a benign lesion, endometriosis shares several characteristics with invasive cancer, has been shown to undergo malignant transformation, and has been associated with an increased risk of epithelial ovarian carcinoma (EOC). Numerous epidemiologic studies have shown an increased risk of EOC among women with endometriosis. This is particularly true for women with endometrioid and clear cell ovarian carcinoma. However, the carcinogenic pathways by which endometriosis associated ovarian carcinoma (EAOC) develops remain poorly understood. Current molecular studies have sought to link endometriosis with EAOC through pathways related to oxidative stress, inflammation and hyperestrogenism. In addition, numerous studies have sought to identify an intermediary lesion between endometriosis and EAOC that may allow for the identification of endometriosis at greatest risk for malignant transformation or for the prevention of malignant transformation of this common gynecologic disorder. The objective of the current article is to review the current data regarding the molecular events associated with EAOC development from endometriosis, with a primary focus on malignancies of the endometrioid and clear cell histologic sub-types.

Involvement of autophagy in ovarian cancer: a working hypothesis

Autophagy is a lysosomal-driven catabolic process that contributes to preserve cell and tissue homeostases through the regular elimination of damaged, aged and redundant self-constituents. In normal cells, autophagy protects from DNA mutation and carcinogenesis by preventive elimination of pro-oxidative mitochondria and protein aggregates. Mutations in oncogenes and oncosuppressor genes dysregulate autophagy. Up-regulated autophagy may confer chemo- and radio-resistance to cancer cells, and also a pro-survival advantage in cancer cells experiencing oxygen and nutrient shortage. This fact is the rationale for using autophagy inhibitors along with anti-neoplastic therapies. Yet, aberrant hyper-induction of autophagy can lead to cell death, and this phenomenon could also be exploited for cancer therapy. The actual level of autophagy in the cancer cell is greatly affected by vascularization, inflammation, and stromal cell infiltration. In addition, small non-coding microRNAs have recently emerged as important epigenetic modulators of autophagy. The present review focuses on the potential involvement of macroautophagy, and on its genetic and epigenetic regulation, in ovarian cancer pathogenesis and progression.

High frequency of allelic loss at the BRCA1 locus in ovarian cancers: clinicopathologic and molecular associations

BRCA1 dysfunction may occur by different mechanisms that are rarely evaluated concomitantly. We aimed to analyze BRCA1 germline mutations, loss of heterozygosity (LOH) and promoter methylation in unselected ovarian carcinomas in the context of their clinicopathologic characteristics and other molecular changes. BRCA1 mutations were analyzed in 257 carcinomas using single-strand conformation polymorphism (SSCP), heteroduplex, and sequencing methods. LOH at the BRCA1 locus was screened for in 180 cancers. Methylation analysis was performed for 241 tumors using quantitative methylation specific PCR (qMSP). BRCA1 alterations, comprising germline mutations, allelic loss, and/or aberrant promoter methylation, were found in 77.6% (125/161) of ovarian carcinomas. Patients with germline mutations were younger than non-carriers (P < 0.0001). Germline mutations and LOH were associated with advanced stages (P=0.009, P < 0.0001), high tumor grade (P=0.005, P < 0.0001), and TP53 mutations (P=0.003, P < 0.0001, for mutations and LOH, respectively). LOH was also associated with the serous histological type (P=0.004) and PIK3CA amplification (P=0.003). Aberrant promoter methylation was associated with LOH (P=0.017) and absence of germline mutations (P=0.037). The high frequency of LOH at the BRCA1 locus suggests that LOH may be an important mechanism of BRCA1 deficiency in ovarian carcinomas. Tumors with various BRCA1 alterations have a similar phenotype of high-grade, high-stage carcinomas with frequent TP53 mutations.

Prognostic impact of concomitant p53 and PTEN on outcome in early stage (FIGO I-II) epithelial ovarian cancer

INTRODUCTION

The objective of the study was to evaluate the prognostic effect of p53, PTEN, and concomitant p53 PTEN status on clinicopathologic features, recurrent disease, and disease-free survival (DFS) of 131 patients in FIGO stages I to II with epithelial ovarian cancer.

METHODS

The technique of tissue microarray and immunohistochemistry was used for the detection of positivity of the biologic markers p53 and PTEN.

RESULTS

In the complete series, the 5-year DFS rate was 68%, and the overall survival rate was 71%. Positive staining for p53 and PTEN was detected in 25% and 22% of cases, respectively. Positivity of p53 was associated with tumor grade in the total series but not in the subgroup of serous tumors. In survival analysis, there was worse survival (P = 0.003) in the group of patients with p53-positive tumors compared with the group of patients with p53-negative tumors with DFS of 62% and 82%, respectively. Furthermore, DFS was 15% for the subgroup of patients with concomitant p53-positivity and PTEN-negativity of tumors compared with DFS of 62% for others in 1 group (p53+PTEN+, p53-PTEN+, p53-PTEN-) at 100 months. The difference was highly significant (P = 0.006). FIGO stage (odds ratio = 8.0) and p53 PTEN status (odds ratio = 0.6) were predictive factors for tumor recurrences in a logistic regression and prognostic factors with hazard ratios (HRs) of 4.0 and 0.6, respectively, in a multivariate Cox regression analysis. In a separate Cox regression analysis, FIGO stage (HR = 3.6) and p53 status (HR = 2.0) were prognostic factors for DFS. For serous tumors (n = 51) recurrent disease was associated with FIGO stage (P = 0.013), and p53 loss (P = 0.029) but not with FIGO grade (P = 0.169).

CONCLUSIONS

p53 status divides ovarian carcinomas into 2 subgroups after prognosis, also in serous tumors. Presence of PTEN in p53-positive tumors seems to protect from bad prognosis and absence of PTEN seems to worsen prognosis in early stages.

Differential analysis of ovarian and endometrial cancers identifies a methylator phenotype

Despite improved outcomes in the past 30 years, less than half of all women diagnosed with epithelial ovarian cancer live five years beyond their diagnosis. Although typically treated as a single disease, epithelial ovarian cancer includes several distinct histological subtypes, such as papillary serous and endometrioid carcinomas. To address whether the morphological differences seen in these carcinomas represent distinct characteristics at the molecular level we analyzed DNA methylation patterns in 11 papillary serous tumors, 9 endometrioid ovarian tumors, 4 normal fallopian tube samples and 6 normal endometrial tissues, plus 8 normal fallopian tube and 4 serous samples from TCGA. For comparison within the endometrioid subtype we added 6 primary uterine endometrioid tumors and 5 endometrioid metastases from uterus to ovary. Data was obtained from 27,578 CpG dinucleotides occurring in or near promoter regions of 14,495 genes. We identified 36 locations with significant increases or decreases in methylation in comparisons of serous tumors and normal fallopian tube samples. Moreover, unsupervised clustering techniques applied to all samples showed three major profiles comprising mostly normal samples, serous tumors, and endometrioid tumors including ovarian, uterine and metastatic origins. The clustering analysis identified 60 differentially methylated sites between the serous group and the normal group. An unrelated set of 25 serous tumors validated the reproducibility of the methylation patterns. In contrast, >1,000 genes were differentially methylated between endometrioid tumors and normal samples. This finding is consistent with a generalized regulatory disruption caused by a methylator phenotype. Through DNA methylation analyses we have identified genes with known roles in ovarian carcinoma etiology, whereas pathway analyses provided biological insight to the role of novel genes. Our finding of differences between serous and endometrioid ovarian tumors indicates that intervention strategies could be developed to specifically address subtypes of epithelial ovarian cancer.

KRAS mutations in ovarian low-grade endometrioid adenocarcinoma: association with concurrent endometriosis

The association between ovarian endometrioid adenocarcinoma and endometriosis is well established. However, not all endometrioid adenocarcinomas are directly related to endometriosis, and it has been suggested that there may be clinicopathologic differences between endometriosis-positive and endometriosis-negative tumors. Molecular alterations in endometrioid adenocarcinoma include KRAS and BRAF mutations, but the incidence of these abnormalities in previous reports has been highly variable (0%-36% and 0%-24%, respectively). This may be explained by relatively small sample sizes in earlier studies but could also reflect difficulties in accurately classifying high-grade ovarian malignancies. In the current study, we investigated KRAS and BRAF mutations in 78 low-grade (FIGO grade 1 and 2) endometrioid adenocarcinomas and compared the results with the presence of endometriosis in the tumor-associated ovary and/or in other pelvic sites. KRAS mutations were identified in 12 (29%) of 42 endometriosis-associated endometrioid adenocarcinomas with satisfactory analysis but in only 1 (3%) of 29 tumors in which endometriosis was not identified. BRAF mutation was identified only in a single endometriosis-associated case. These findings support the hypothesis that endometriosis-associated and independent endometrioid adenocarcinoma may develop via different molecular pathways and that KRAS mutations have an important role only in the former tumors. In contrast, BRAF mutations do not appear to have a significant role in either endometrioid adenocarcinoma subgroup. This may be relevant to future targeted therapies in patients with high-stage or recurrent disease and indicate that histopathologists should carefully examine endometrioid adenocarcinoma specimens, including nonneoplastic tissues, for the presence of endometriosis.

Targeting the PI3K signaling pathway in cancer therapy

INTRODUCTION

The PI3K signaling pathway is involved in the regulation of cancer cell growth, motility, survival and metabolism. The pathway is frequently active in many different types of cancer-e.g., breast, bladder, prostate, thyroid, ovarian and NSCLC. Targetable genetic aberrations in this pathway give us many opportunities for development of targeted therapies for different types of cancer.

AREAS COVERED

The genetic alterations in the PI3K/mammalian target of rapamycin (mTOR)/Akt pathway, as well as the drugs that target this pathway, either alone, in combination with other targeted agents or in chemotherapy. Targeted inhibitors of the PI3K pathway currently being tested in clinical trials in different types of human cancer.

EXPERT OPINION

Small-molecule inhibitors targeting the PI3K/Akt/mTOR pathway show some success with these agents in current clinical trials. For further improvement in response, molecular correlates that can be used for patient selection, need to be determined. A more efficient and effective way to screen for patients to determine which patients are most likely to benefit from PI3K pathway inhibitors is also needed.

Morphologic manifestations of gene-specific molecular alterations ("genetic addictions") in mouse models of disease

Neoplasia in both animals and humans results in part from lasting activation of tumor-promoting genes ("oncogenes") or diminished function of genes responsible for preventing neoplastic induction ("tumor suppressor genes"). The concept of "genetic addiction" has emerged to indicate that neoplastic cells cannot maintain a malignant phenotype without sustained genotypic abnormalities related to aberrant activity of oncogene(s) and/or inactivity of tumor suppressor gene(s). Interestingly, some genetic abnormalities reliably produce distinct morphologic patterns that can be used as structural signatures indicating the presence of a specific molecular alteration. Examples of such consistent genetic/microanatomic pairings have been identified for mutated oncogenes, such as rising mucin-producing capacity with RAS overexpression, and mutated tumor suppressor genes-including PTEN eliciting cell hypertrophy, RB1 dictating neuroendocrine differentiation, and TRP53 encouraging sarcomatous transformation. Familiarity with the concept of genetic addiction, as well as the ability to recognize such regular genomic-phenotypic relationships, are of paramount importance for comparative pathologists who are engaged in phenotyping genetically engineered mice to help unravel genomic intricacies in both health and disease.

Endocervical-like (Müllerian) mucinous borderline tumours of the ovary are frequently associated with the KRAS mutation

AIMS

  Clinicopathological aspects of the endocervical-like mucinous borderline tumour of the ovary (EMBT), including higher frequencies of bilaterality, endometriosis and hormone receptor reactivity, and often admixtures of various Müllerian-type epithelia, closely resembles endometrioid tumour more than mucinous borderline tumour of the intestinal type (IMBT). Thus, the aims of this study were to determine whether EMBT is really a subtype of mucinous borderline tumours, as shown in the current classification system, and to determine the best classification for EMBT.

METHODS AND RESULTS

  The clinicopathological and immunohistochemical features of 17 EMBTs were analysed, including oestrogen receptor (ER), progesterone receptor (PR), PTEN, cytokeratins (CK) 7 and 20, and β-catenin. Additionally, mutational analyses of the KRAS (exon 1) and PTEN genes (all nine exons) were performed in all cases, and the results were compared with literature findings for IMBT and endometrioid tumours. Twelve patients (71%) were confirmed histologically to have endometriosis in one or both ovaries. In seven cases, gradual transitions from endometriotic foci to the EMBT were identified. Immunohistochemically, all cases were reactive for ER and PR, with no nuclear expression of β-catenin. CK7 positivity was strong in all patients, whereas there was no reactivity for CK20. PTEN reactivity was diffuse in the nuclei of epithelial and underlying stromal cells. Sixty-nine per cent showed KRAS mutations in exon 1 and codon 12, but no PTEN mutation was identified in any of the nine exons.

CONCLUSION

  Our study suggests that EMBT has features of both mucinous and endometrioid tumours and is an additional tumour type arising in endometriosis. While clinicopathological features of EMBTs are closer to endometrioid tumours, they still have molecular characteristics closer to IMBTs.

A novel germline PALB2 deletion in Polish breast and ovarian cancer patients

Background

PALB2 protein was recently identified as a partner of BRCA1 and BRCA2 which determines their proper function in DNA repair.

Methods

Initially, the entire coding sequence of the PALB2 gene with exon/intron boundaries was evaluated by the PCR-SSCP and direct sequencing methods on 70 ovarian carcinomas. Sequence variants of interest were further studied on enlarged groups of ovarian carcinomas (total 339 non-consecutive ovarian carcinomas), blood samples from 334 consecutive sporadic and 648 consecutive familial breast cancer patients, and 1310 healthy controls from central Poland.

Results

Ten types of sequence variants were detected, and among them four novel polymorphisms: c.2996+58T>C in intron 9; c.505C>A (p.L169I), c.618T>G (p.L206L), both in exon 4; and c.2135C>T (A712V) in exon 5 of the PALB2 gene. Another two polymorphisms, c.212-58A>C and c.2014G>C (E672Q) were always detected together, both in cancer (7.5% of patients) and control samples (4.9% of controls, p = 0.2). A novel germline truncating mutation, c.509_510delGA (p.R170fs) was found in exon 4: in 2 of 339 (0.6%) unrelated ovarian cancer patients, in 4 of 648 (0.6%) unrelated familial breast cancer patients, and in 1 of 1310 controls (0.08%, p = 0.1, p = 0.044, respectively). One ovarian cancer patient with the PALB2 mutation had also a germline nonsense mutation of the BRCA2 gene.

Conclusions

The c.509_510delGA is a novel PALB2 mutation that increases the risk of familial breast cancer. Occurrence of the same PALB2 alteration in seven unrelated women suggests that c.509_510delGA (p.R170fs) is a recurrent mutation for Polish population.

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

Background

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

Methodology/Principal Findings

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

Conclusions/Significance

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

Ovarian cancer update: lessons from morphology, molecules, and mice

Ovarian carcinomas are a heterogeneous group of neoplasms. Pathologists currently employ a morphology-based classification system to divide ovarian carcinomas into major subgroups based on degree (tumor grade) and type of differentiation (eg, serous, endometrioid, clear cell, or mucinous). Molecular studies have shown that specific genetic defects are likely to be present in certain histologic types of ovarian carcinomas and unlikely to be present in others. Within the serous and endometrioid carcinomas, the molecular defects in low-grade versus high-grade tumors also appear to be largely distinct. Recently, mouse models of ovarian carcinoma have been developed that recapitulate many of the morphologic features and biologic behavior of selected subtypes of ovarian cancer. It is expected that these mouse models will yield new insights into ovarian cancer pathogenesis and prove useful for preclinical testing of novel strategies for ovarian cancer treatment.

Identification of potential serum markers for endometrial cancer using protein expression profiling

OBJECTIVES

Screening method of endometrial cancer (EC) has not been established yet. Our study was to explore serum biomarkers of EC patients using surface-enhanced laser desorption and ionization-time-of-flight mass spectrometry (SELDI-TOF MS).

METHODS

Serum samples from 65 EC patients and 40 controls were analyzed by SELDI-TOF MS (training set). Single- and multi-variant analyses were performed to compare protein profiles in serum of EC patients and healthy controls. Subsequently, blind test set including 40 EC patients and 40 controls were analyzed for validation.

RESULTS

A panel of four biomarker candidates were selected in training set analysis. These markers could also distinguish stage I patients from controls. Among them, two biomarkers were purified and identified as apolipoprotein A1 and a modified form of apolipoprotein C1. Screening for blind test set using dual-biomarker analysis yielded a sensitivity of 82% and a specificity of 86%.

CONCLUSIONS

Involvement of apolipoproteins with EC is first suggested in this study. In addition to possibility of screening method for EC, findings of these new biomarkers might be related with carcinogenesis or predisposition to EC.

Theoretical model of treatment strategies for clear cell carcinoma of the ovary: focus on perspectives

OBJECTIVES

Among epithelial ovarian cancer (EOC), clear cell carcinomas (CCC) differ from the other histologic types with respect to their clinical characteristics, carcinogenesis and prognosis. The aim of this review is to summarize the current knowledge and future perspective on the new therapeutic targets and treatment strategies for CCC.

MATERIALS AND METHODS

The present article reviews the English language literature for preclinical and clinical trials and promising molecular targets on CCC of the ovary, based on the gene expression profiling studies.

RESULTS

Here, we show that (1) the expression of the genes involved in transcription, signaling, cell cycle, adhesion, matrix, proteinase, and detoxification was greatly increased in the CCC carcinogenesis; (2) upregulation of hepatocyte nuclear factor-1beta (HNF-1beta) and Polo-like kinase (PLK)-Early mitotic inhibitor-1 (Emi1) as well as their downstream targets are specifically found in most CCC. The promising molecular targeting approach will emerge in the context of HNF-1beta and PLK-Emi1 biology; and 3) several significant common pathways observed in CCC of the ovary overlap the datasets identified in CCC of the kidney. To improve the outcome in CCC therapy, we must learn various adaptive treatment strategies for renal CCC, although it is not supported by any preliminary clinical data.

CONCLUSION

The inhibitors that target HNF-1beta and PLK-Emi1 and their downstream signaling molecules would be evaluated. In addition, the therapy currently used in renal CCC should be considered as an alternative for the present treatments or an attractive therapeutic option for ovarian CCC. The challenges accompanying the recent advance are described in this review article.

Rapamycin by itself and additively in combination with carboplatin inhibits the growth of ovarian cancer cells

OBJECTIVE

The current standard treatment for ovarian carcinoma, consisting of surgery followed by chemotherapy with carboplatin and paclitaxel, is fraught with a high rate of recurrences. We hypothesized that targeted inhibition of specific signaling pathways in combination with conventional drugs may increase chemotherapeutic efficacy.

METHODS

We analyzed the expression and activation profiles of various signaling pathways in nine established ovarian cancer cell lines (CAOV-3, ES2, PA-1, SKOV-3, NIHOVCAR3, OV90, TOV112D, A1847, A2780) and 24 freshly procured human ovarian tumors. The PI3 kinase pathway component Akt was frequently overexpressed and/or activated in tumor cells. The effect of several PI3K pathway inhibitors (rapamycin, LY294002, SH-6) and rapamycin in combination with carboplatin on various tumor cell growth characteristics was tested in cell lines and fresh tumor-derived transient monolayer and organ cultures.

RESULTS

Rapamycin by itself and additively with carboplatin inhibited the growth and invasion, and increased the sensitivity to anoikis of most of the ovarian cancer cell lines and fresh tumors. The additive inhibitory effect may be due to enhanced apoptosis as demonstrated by Poly-ADP-Ribose Polymerase (PARP) cleavage and Annexin V staining in cells treated with both rapamycin and carboplatin.

CONCLUSIONS

Rapamycin in combination with standard chemotherapeutic agents may improve the efficiency of ovarian cancer treatment.

Ovarian cancer

Ovarian carcinomas are a heterogeneous group of neoplasms and are traditionally subclassified based on type and degree of differentiation. Although current clinical management of ovarian carcinoma largely fails to take this heterogeneity into account, it is becoming evident that each major histological type has characteristic genetic defects that deregulate specific signaling pathways in the tumor cells. Moreover, within the most common histological types, the molecular pathogenesis of low-grade versus high-grade tumors appears to be largely distinct. Mouse models of ovarian carcinoma have been developed that recapitulate many of the morphological features, biological behavior, and gene-expression patterns of selected subtypes of ovarian cancer. Such models will likely prove useful for studying ovarian cancer biology and for preclinical testing of molecularly targeted therapeutics, which may ultimately lead to better clinical outcomes for women with ovarian cancer.

Focused glycomic analysis of the N-linked glycan biosynthetic pathway in ovarian cancer

Epithelial ovarian cancer is the deadliest female reproductive tract malignancy in Western countries. Less than 25% of cases are diagnosed when the cancer is confined, however, pointing to the critical need for early diagnostics for ovarian cancer. Identifying the changes that occur in the glycome of ovarian cancer cells may provide an avenue to develop a new generation of potential biomarkers for early detection of this disease. We performed a glycotranscriptomic analysis of endometrioid ovarian carcinoma using human tissue, as well as a newly developed mouse model that mimics this disease. Our results show that the N-linked glycans expressed in both nondiseased mouse and human ovarian tissues are similar; moreover, malignant changes in the expression of N-linked glycans in both mouse and human endometrioid ovarian carcinoma are qualitatively similar. Lectin reactivity was used as a means for rapid validation of glycan structural changes in the carcinomas that were predicted by the glycotranscriptome analysis. Among several changes in glycan expression noted, the increase of bisected N-linked glycans and the transcripts of the enzyme responsible for its biosynthesis, GnT-III, was the most significant. This study provides evidence that glycotranscriptome analysis can be an important tool in identifying potential cancer biomarkers.

KRAS or BRAF mutation status is a useful predictor of sensitivity to MEK inhibition in ovarian cancer

This study examined the status of KRAS and BRAF mutations, in relation to extracellular signal-regulated protein kinase (ERK) activation in 58 ovarian carcinomas to clarify the clinicopathological and prognostic significance of KRAS/BRAF mutations. Somatic mutations of either KRAS or BRAF were identified in 12 (20.6%) out of 58 ovarian carcinomas. The frequency of KRAS/BRAF mutations in conventional serous high-grade carcinomas (4.0% : 1/25) was significantly lower than that in the other histological type (32.3% : 10/31). Phosphorylated ERK1/2 (p-ERK1/2) expression was identified in 18 (38.2%) out of 45 ovarian carcinomas. KRAS/BRAF mutation was significantly correlated with International Federation of Gynecology and Obstetrics (FIGO) stage I, II (P<0.001), and p-ERK1/2 (P<0.001). No significant correlations between KRAS/BRAF mutations or p-ERK1/2 expression and overall survival were found in patients with ovarian carcinoma treated with platinum and taxane chemotherapy (P=0.2460, P=0.9339, respectively). Next, to clarify the roles of ERK1/2 activation in ovarian cancers harbouring KRAS or BRAF mutations, we inactivated ERK1/2 in ovarian cancer cells using CI-1040. Cl-1040 is a compound that selectively inhibits MAP kinase kinase (MEK), an upstream regulator of ERK1/2, and thus prevents ERK1/2 activation. Profound growth inhibition and apoptosis were observed in CI-1040-treated cancer cells with mutations in either KRAS or BRAF in comparison with the ovarian cancer cells containing wild-type sequences. This was evident in both in vitro and in vivo studies. The findings in this study indicate that an activated ERK1/2 pathway is critical to tumour growth and survival of ovarian cancers with KRAS or BRAF mutations. Furthermore, they suggest that the CI-1040-induced phenotypes depend on the mutational status of KRAS and BRAF in ovarian cancers. Therefore, ovarian cancer patients with KRAS or BRAF mutations may benefit from CI-1040 treatment.

PTEN promoter methylation and LOH of 10q22-23 locus in PTEN expression of ovarian clear cell adenocarcinomas

OBJECTIVES

Loss of phosphatase and tensin homolog (PTEN) expression is common in ovarian clear cell adenocarcinomas (OCCA), but PTEN mutations are not frequently observed in OCCA. The mechanism of PTEN gene silencing in OCCA is still not clear.

MATERIALS AND METHODS

Immunohistochemical analysis of PTEN expression was performed in 40 OCCA paraffin-embedded tissues. PTEN promoter methylation in 24 OCCA tissues and 5 OCCA cell lines was examined by methylation-specific PCR. Eighteen OCCA patients and 13 serous adenocarcinomas were analyzed for loss of heterozygosity (LOH) at 10q23 with five polymorphic markers.

RESULTS

Of the 40 OCCAs, 37.5% (15/40) had reduced PTEN immunoreactivity, LOH was found in 33% (6/18) of OCCAs, and 31% (4/13) of serous adenocarcinomas. In the 33% of OCCAs with LOH, only 33% (2/6) lost PTEN expression. PTEN promoter was unmethylated in 5 OCCA cell lines and 24 OCCA tissues detected by MSP-PCR. No significant correlation between PTEN expression and advanced stage disease or overall survival was found.

CONCLUSION

Our results indicate that reduced PTEN expression was detected in more than one third of OCCA cases. Neither PTEN promoter methylation nor LOH at 10q23 locus is significantly related to PTEN inactivation and is not an adverse prognostic factor in OCCA.

PTEN in brain tumors

The tumor suppressor PTEN dephosphorylates phospholipids generated through the activity of PI3K. PTEN thus antagonizes PI3K activity and regulates a multitude of cellular processes such as angiogenesis, motility, invasiveness, survival and proliferation, all of which can initiate and sustain the malignant phenotype. Although PTEN's lipid phosphatase activity is key to its tumor suppressive functions, it also dephosphorylates protein substrates and interacts with other key regulatory molecules, salient among them the tumor suppressor p53. Given the critical roles of PTEN in cellular homeostasis, it is not surprising that both PTEN expression levels and PTEN protein activities are tightly controlled by a complex conglomeration of molecules that regulate post-translational modifications, subcellular localization, transcriptional activation and transcriptional repression. As one of the most commonly altered molecules in human disease, PTEN plays an important role in a myriad of signaling cascades, and plays a central role in normal brain development and brain tumor pathogenesis. As such it influences prognosis of human cancer, predicts response to therapy, constitutes the lynchpin of genetic syndromes, and may underlie neurocognitive abnormalities such as autism spectrum disorders and Alzheimer's disease. Thus, targeting PTEN and its signaling affiliates sows the seeds for combating not only cancer but also neurocognitive disorders.

Mouse model of human ovarian endometrioid adenocarcinoma based on somatic defects in the Wnt/beta-catenin and PI3K/Pten signaling pathways

One histologic subtype of ovarian carcinoma, ovarian endometrioid adenocarcinoma (OEA), frequently harbors mutations that constitutively activate Wnt/beta-catenin-dependent signaling. We now show that defects in the PI3K/Pten and Wnt/beta-catenin signaling pathways often occur together in a subset of human OEAs, suggesting their cooperation during OEA pathogenesis. Deregulation of these two pathways in the murine ovarian surface epithelium by conditional inactivation of the Pten and Apc tumor suppressor genes results in the formation of adenocarcinomas morphologically similar to human OEAs with 100% penetrance, short latency, and rapid progression to metastatic disease in upwards of 75% of mice. The biological behavior and gene expression patterns of the murine cancers resemble those of human OEAs with defects in the Wnt/beta-catenin and PI3K/Pten pathways.