Cytogenetics and molecular genetics of ovarian cancer

HE4 Overexpression by Ovarian Cancer Promotes a Suppressive Tumor Immune Microenvironment and Enhanced Tumor and Macrophage PD-L1 Expression

Ovarian cancer is a highly fatal malignancy characterized by early chemotherapy responsiveness but the eventual development of resistance. Immune targeting therapies are changing treatment paradigms for numerous cancer types but have had minimal success in ovarian cancer. Through retrospective patient sample analysis, we have determined that high human epididymis protein 4 (HE4) production correlates with multiple markers of immune suppression in ovarian cancer, including lower CD8⁺ T cell infiltration, higher PD-L1 expression, and an increase in the peripheral monocyte to lymphocyte ratio. To further understand the impact that HE4 has on the immune microenvironment in ovarian cancer, we injected rats with syngeneic HE4 high- and low-expressing cancer cells and analyzed the differences in their tumor and ascites immune milieu. We found that high tumoral HE4 expression promotes an ascites cytokine profile that is rich in myeloid-recruiting and differentiation factors, with an influx of M2 macrophages and increased arginase 1 production. Additionally, CTL activation is significantly reduced in the ascites fluid, and there is a trend toward lower CTL infiltration of the tumor, whereas NK cell recruitment to the ascites and tumor is also reduced. PD-L1 expression by tumor cells and macrophages is increased by HE4 through a novel posttranscriptional mechanism. Our data have identified HE4 as a mediator of tumor-immune suppression in ovarian cancer, highlighting this molecule as a potential therapeutic target for the treatment of this devastating disease.

Morphological and molecular basis of ovarian serous carcinoma

Serous carcinoma is the most common type of epithelial ovarian cancer. In this review, we provide a comprehensive picture of ovarian serous cancers from multiple aspects: the first part of this review summarizes the morphological, histological, and immunological signatures of ovarian serous carcinoma; subsequently, we review the history of the evolvement of different grading systems used in ovarian serous cancer; in the end, we focus on characterizing the genetics that underlie the 2-tiered pathways through which ovarian serous cancers are believed to arise: the low-grade and the high-grade pathways.

Genome profiling of ovarian adenocarcinomas using pangenomic BACs microarray comparative genomic hybridization

Background

Routine cytogenetic investigations for ovarian cancers are limited by culture failure and poor growth of cancer cells compared to normal cells. Fluorescence in situ Hybridization (FISH) application or classical comparative genome hybridization techniques are also have their own limitations in detecting genome imbalance especially for small changes that are not known ahead of time and for which FISH probes could not be thus designed.

Methods

We applied microarray comparative genomic hybridization (A-CGH) using one mega base BAC arrays to investigate chromosomal disorders in ovarian adenocarcinoma in patients with familial history.

Results

Our data on 10 cases of ovarian cancer revealed losses of 6q (4 cases mainly mosaic loss), 9p (4 cases), 10q (3 cases), 21q (3 cases), 22q (4 cases) with association to a monosomy X and gains of 8q and 9q (occurring together in 8 cases) and gain of 12p. There were other abnormalities such as loss of 17p that were noted in two profiles of the studied cases. Total or mosaic segmental gain of 2p, 3q, 4q, 7q and 13q were also observed. Seven of 10 patients were investigated by FISH to control array CGH results. The FISH data showed a concordance between the 2 methods.

Conclusion

The data suggest that A-CGH detects unique and common abnormalities with certain exceptions such as tetraploidy and balanced translocation, which may lead to understanding progression of genetic changes as well as aid in early diagnosis and have an impact on therapy and prognosis.

Correlation between 6q25.3 deletion status and survival in pediatric intracranial ependymomas

Losses and rearrangements of genetic material on chromosome 6q are frequently found in several human malignancies, including primary central nervous system tumors. We previously used microsatellite analysis of ependymomas to identify frequent deletions in regions 6q15 approximately q16, 6q21 approximately q22.1, and 6q24.3 approximately q25.3. To refine our preliminary analysis of potential prognostic regions, we used a panel of 25 microsatellite markers located between 6q15 and 6qter in 49 pairs of matched normal and tumor specimens from 28 children and 21 adults with ependymoma. Allelic deletions were detected in 34 of 49 patients (69%), and two common regions of deletions (6q24.3 and 6q25.2 approximately q25.3) were identified. A short segment of approximately 0.4 Mb between D6S1612 and D6S363 on 6q25.3, containing the SNX9 and SYNJ2 genes, exhibited the highest number of aberrations (n = 38). Pediatric tumors showed slightly fewer aberrations (64%) than adult tumors (76%) and also predominantly exhibited small interstitial deletions, in contrast to the extensive losses of genetic material in adults. Pediatric anaplastic intracranial (supra- and infratentorial) ependymomas harboring the 6q25.3 deletion (n = 9) showed significantly longer overall survival than did patients of the same group without the aberration (n = 6), independent of the extent of resection (P = 0.013). This supports the identified deletion on 6q25.3 as a candidate favorable prognostic parameter and warrants further investigation.

Gene expression profile of ovarian serous papillary carcinomas: identification of metastasis-associated genes

OBJECTIVE

The purpose of this study was to identify genes that are highly differentially expressed in metastatic serous papillary ovarian tumors (MET) when compared with primary ovarian serous carcinomas (OSPC).

STUDY DESIGN

An oligonucleotide microarray with probe sets complementary to >14,500 human genes was used to determine whether patterns of gene expression may differentiate OSPC from MET in 31 snap-frozen serous papillary ovarian carcinomas (ie, 14 primary OSPC and 17 omental metastasis [MET]).

RESULTS

Hierarchic cluster analysis of gene expression in OSPC and MET identified 156 genes that exhibited > 2-fold differences (P < .05) and that distinguished OSPC from MET. A number of invasion and metastasis predictive genes (including plasminogen activator; matrix metalloproteinase; matrix structural constituent genes encoding products with collagen, heparin, and hyaluronic acid binding activity; genes encoding receptors for insulin-like growth factors; vascular endothelial growth factor; endothelin type A; fibroblast growth factor; thrombospondin 1 and 2; type A and B integrins, and chemokines [stromal cell-derived factor 1 (CXCL12)]) were found among the 120 genes that were highly differentially overexpressed in MET, when compared with OSPC. Down-regulated genes in MET compared with OSPC included hepsin and testisin. Overexpression of CXCL12, matrix metalloproteinase, plasminogen activator, type A and B integrins, and hepsin genes was validated by quantitative real-time polymerase chain reaction in all samples. Finally, overexpression of CXCL12 in MET, when compared with OSPC, was validated at the protein level by immunohistochemistry.

CONCLUSION

Gene expression profiling may differentiate metastatic ovarian cancer from primary OSPC. The identification of metastasis-associated genes may provide a foundation for the development of new type-specific diagnostic strategies and treatment for metastatic ovarian cancer.

Molecular biomarkers for cancer detection in blood and bodily fluids

Cancer is a major and increasing public health problem worldwide. Traditionally, the diagnosis and staging of cancer, as well as the evaluation of response to therapy have been primarily based on morphology, with relatively few cancer biomarkers currently in use. Conventional biomarker studies have been focused on single genes or discrete pathways, but this approach has had limited success because of the complex and heterogeneous nature of many cancers. The completion of the human genome project and the development of new technologies have greatly facilitated the identification of biomarkers for assessment of cancer risk, early detection of primary cancers, monitoring cancer treatment, and detection of recurrence. This article reviews the various approaches used for development of such markers and describes markers of potential clinical interest in major types of cancer. Finally, we discuss the reasons why so few cancer biomarkers are currently available for clinical use.

Human leucocyte antigen (HLA) A2 as a negative clinical prognostic factor in patients with advanced ovarian cancer

OBJECTIVES

Major histocompatibility complex antigens are mandatory for the immune response, and a genetic imbalance may be linked to tumor escape. We have previously characterized a cluster of ovarian cancer patients with high incidence of HLA-A2. To find a prognostic relevance, the presence of HLA-A2 was correlated to defined clinical parameters.

METHODS

A population-based set of 97 patients with confirmed epithelial ovarian cancer were recorded in a database by age, histology, stage, surgery and treatment. At the time the study was initiated, the majority of the patients were not alive and HLA-A2 expression was therefore determined by PCR/sequence-specific oligonucleotide hybridization using DNA extracted from paraffin-imbedded tissue specimens.

RESULTS

88 patients with a median age of 65 years (36-87) could be evaluated. 44% were serous adenocarcinomas, 28% endometrioid, 6% mucinous, 13% clear cell carcinomas, 7% undifferentiated and 2% other epithelial tumors. Stages I-II comprised 33% and stages III-IV 67%. In stages III-IV and serous histology, 73% were HLA-A2 positive. Cox analysis, in this group, showed high univariate (HR7.16; CI 2.04-25.03; P = 0.002) and multivariate (HR 6.8; CI 2.10-22.4; P = 0.001) Hazard Ratios. None of the HLA-A2 positive patients survived 5 years, compared to more than 50% of the HLA-A2 negative patients.

CONCLUSIONS

HLA-A2 is a negative factor for survival in women with serous adenocarcinomas of the ovary in stages III-IV. This finding has implications for clinical patient management. Association with known oncogenes needs further analysis.

Non-random structural chromosomal changes in ovarian cancer: i(5p) a novel recurrent abnormality

Ovarian cancer represents the leading cause of death among patients with gynecological cancer. The genetic changes underlying the initiation and progression of ovarian cancer have not been well defined. However, non-random structural chromosomal changes have been identified with common chromosomal breakpoints. We have studied cytogenetically 15 cases of ovarian adenocarcinomas by a direct culture of cancer cells and a G-banding technique investigating the presence of recurrent structural aberrations with common chromosomal breakpoints. Among very complex structural rearrangements found, we could recognize recurrent structural aberrations involving according to frequency chromosomal regions 3p13-14, 11p15, 19q13, 3q21, 11q23, 11q10, 1p13, 1p36, and 17q24-25. Isochromosomes i(5p), i(17q), i(8q) and i(11q) were also observed. Isochromosome i(5p), rarely reported in ovarian cancer was found in seven cases suggesting that it may be a novel recurrent abnormality. Translocations t(1;11), t(3;19), t(3;17), t(7;11) and t(11;17) were also identified. Conventional cytogenetics continues to be valuable detecting the presence of non-random chromosomal breakpoints and facilitating the identification of genes implicated in tumorigenesis.

Analysis of Molecular Aberrations in Ovarian Cancer Allows Novel Target Identification

The completion of the Human Genome Project and recent advances in functional genomic, proteomic, and high-throughput screening methodologies have provided powerful tools for determining the mechanisms of human diseases, including complex polygenic diseases such as ovarian cancer. These developments may eventually lead to individualized molecular medicine, which is the treatment of patients based on the underlying genetic defects in their tumours and their own genetic makeup. A plethora of novel therapeutic agents that act on specific molecular targets defined by cancer genetics are under development. There is thus a great deal of interest in determining how specific genes and proteins function in cancers, in order to further the understanding of cancer initiation and progression; to aid in identifying biomarkers, therapeutic targets, and determinants of drug responsiveness; and to progress the development of novel antitumour agents.

The role of protein elongation factor eEF1A2 in ovarian cancer

Frequent gains of chromosome 20q12-13 in ovarian tumors indicate that at least one important oncogene is found at that locus. One of the genes there is EEF1A2, which maps to 20q13.3 and encodes protein elongation factor eEF1A2. This review will focus on recent evidence indicating that EEF1A2 is an important ovarian oncogene and that the protein elongation network can activate tumorigenesis and inhibit apoptosis.