Genetic and cytogenetic observations among different types of ovarian tumors are compatible with a progression model underlying ovarian tumorigenesis

Profile of Chromosomal Alterations, Chromosomal Instability and Clonal Heterogeneity in Colombian Farmers Exposed to Pesticides

Pesticides are a group of environmental pollutants widely used in agriculture to protect crops, and their indiscriminate use has led to a growing public awareness about the health hazards associated with exposure to these substances. In fact, exposure to pesticides has been associated with an increased risk of developing diseases, including cancer. In a study previously published by us, we observed the induction of specific chromosomal alterations and, in general, the deleterious effect of pesticides on the chromosomes of five individuals exposed to pesticides. Considering the importance of our previous findings and their implications in the identification of cytogenetic biomarkers for the monitoring of exposed populations, we decided to conduct a new study with a greater number of individuals exposed to pesticides. Considering the above, the aim of this study was to evaluate the type and frequency of chromosomal alterations, chromosomal variants, the level of chromosomal instability and the clonal heterogeneity in a group of thirty-four farmers occupationally exposed to pesticides in the town of Simijacá, Colombia, and in a control group of thirty-four unexposed individuals, by using Banding Cytogenetics and Molecular Cytogenetics (Fluorescence in situ hybridization). Our results showed that farmers exposed to pesticides had significantly increased frequencies of chromosomal alterations, chromosomal variants, chromosomal instability and clonal heterogeneity when compared with controls. Our results confirm the results previously reported by us, and indicate that occupational exposure to pesticides induces not only chromosomal instability but also clonal heterogeneity in the somatic cells of people exposed to pesticides. This study constitutes, to our knowledge, the first study that reports clonal heterogeneity associated with occupational exposure to pesticides. Chromosomal instability and clonal heterogeneity, in addition to reflecting the instability of the system, could predispose cells to acquire additional instability and, therefore, to an increased risk of developing diseases.

Chromosome 11q23.1 is an unstable region in B-cell tumor cell lines

Chromosome 11q23 region is a frequent target of chromosome aberrations in B-cell lymphoid tumors. Here, we present the cytogenetic and molecular characterization of an amplification affecting 11q23.1 in four cell lines derived from B-cell lymphoid tumors. A minimal common region of amplification of 330 kb was identified in three cell lines using Affymetrix Human Mapping 250K arrays. When analyzed with three BAC clones, the amplifications appeared different at cytogenetic level in each cell line. Possibly affected transcripts were evaluated using tiling arrays, and validated by real time PCR. Since no effect of the amplification at the local transcription level was observed, it is possible that 11q23 amplification might mainly represent the effect of unstable chromosomal region.

Comparison of cytogenetic changes between primary and relapsed patients with borderline tumors of the ovary

The aim of this work was to compare cytogenetic changes in primary and relapsed borderline tumors of the ovary. We analyzed 11 tumors (6 primary and 5 relapsed) by conventional GTG banding analysis and fluorescence in situ hybridization. The tumors studied were clinical stages I and III. Genomic imbalances were detected in both investigated groups. In the primary tumors group, only simple chromosome changes were detected. There were gains of chromosome 12, 7, and 8. The presence of additional copies of chromosomes 12 and 7 was independent of histologic subtype, whereas trisomy 8 appeared only in serous tumors. In the group of relapsed borderline tumors, besides trisomies 7 and 12, the structural aberrations of chromosomes 1, 6q, 7q, and 10q were revealed. Gains of tested oncogenes (CCND1 and MYC) have been demonstrated in both groups of investigated tumors. Gains of CCNC1 and MYC genes could be of prognostic value in borderline tumors, but this assumption requires further research.

Gross genomic alterations differ between serous borderline tumors and serous adenocarcinomas--an image cytometric DNA ploidy analysis of 307 cases with histogenetic implications

Our objective was to study the gross genomic alterations in serous borderline tumors and serous adenocarcinomas of the ovary. A retrospective analysis of 245 serous borderline tumors and 62 serous adenocarcinomas from 249 patients was performed using high-resolution image cytometric DNA ploidy analysis. DNA ploidy status, S-phase fraction, and DNA index were evaluated. The majority of serous borderline tumors were diploid (225/245 cases, 92%). The remaining 8% showed an aneuploid peak predominantly with DNA index of less than 1.4. Grades 2 and 3 serous adenocarcinomas were more often (80%) nondiploid, mostly with DNA index exceeding 1.4. Grade 1 serous adenocarcinomas were an intermediate group, more similar to serous borderline tumors. The S-phase fraction increased from serous borderline tumors (mean = 0.6%) through grade 1 serous adenocarcinomas (mean = 2.8%), being highest in grades 2 and 3 adenocarcinomas (mean = 6.8%). Our findings support the hypothesis that serous borderline tumors and grades 2 and 3 serous adenocarcinomas are genomically different lesions, with grade 1 serous adenocarcinomas being an intermediate group more close to borderline tumors.

The eukaryotic translation elongation factor eEF1A2 induces neoplastic properties and mediates tumorigenic effects of ZNF217 in precursor cells of human ovarian carcinomas

Ovarian epithelial carcinomas (OECs) frequently exhibit amplifications at the 20q13 locus which is the site of several oncogenes, including the eukaryotic elongation factor EEF1A2 and the transcription factor ZNF217. We reported previously that overexpressed ZNF217 induces neoplastic characteristics in precursor cells of OEC. Unexpectedly, ZNF217, which is a transcriptional repressor, enhanced expression of eEF1A2. In our study, array comparative genomic hybridization, single nucleotide polymorphism and Affymetrix analysis of ZNF217-overexpressing cell lines confirmed consistently increased expression of eEF1A2 but not of other oncogenes, and revealed early changes in EEF1A2 gene copy numbers and increased expression at crisis during immortalization. We defined the influence of eEF1A2 overexpression on immortalized ovarian surface epithelial cells, and investigated interrelationships between effects of ZNF217 and eEF1A2 on cellular phenotypes. Lentivirally induced eEF1A2 overexpression caused delayed crisis, apoptosis resistance and increases in serum-independence, saturation densities and anchorage independence. siRNA to eEF1A2 reversed apoptosis resistance and reduced anchorage independence in eEF1A2-overexpressing lines. Remarkably, siRNA to eEF1A2 was equally efficient in inhibiting both anchorage independence and resistance to apoptosis conferred by ZNF217 overexpression. Our data define neoplastic properties that are caused by eEF1A2 in nontumorigenic ovarian cancer precursor cells, and suggest that eEF1A2 plays a role in mediating ZNF217-induced neoplastic progression.

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.

Changes in mRNA and protein levels of human HtrA1, HtrA2 and HtrA3 in ovarian cancer

OBJECTIVES

Expression of human HtrA1, HtrA2, HtrA3 and TGF-beta1 genes was examined in ovarian tissue specimens including 19 normal ovaries, 20 benign tumors, 7 borderline tumors, 44 cancers and 8 Krukenberg tumors.

DESIGN AND METHODS

mRNA and protein levels were evaluated by semi-quantitative RT-PCR and Western-blotting methods, respectively.

RESULTS

A statistically significant decrease of HtrA1 and HtrA3 expression in ovarian tumors comparing to normal tissues was observed. A dramatic decrease of HtrA3 mRNA and protein levels in all tumor tissue groups, and a loss of HtrA3 protein in 30% malignant tumors were found. A significant decrease of HtrA1 mRNA, and of HtrA3 mRNA and protein in malignant tumors compared to benign tumors was revealed. HtrA2 expression in tumor tissues was slightly decreased. Expression of TGF-beta1 in tumor tissues was not significantly different compared to control tissues.

CONCLUSIONS

Our results show downregulation of HtrA1 and HtrA3 genes' expression in different types of ovarian tumors and give additional evidence that these genes may function as tumor suppressors.

Serous borderline ovarian tumors in long-term culture: phenotypic and genotypic distinction from invasive ovarian carcinomas

Serous borderline ovarian tumors (SBOTs) are differentiated, slow growing, noninvasive, and have a better prognosis than their invasive counterparts, but recurrence and progression to invasive carcinomas are common, and unlike high-grade serous carcinomas, they tend to be nonresponsive to chemotherapy. However, due to a lack of culture systems and animal models, information about the properties of SBOT and their changes with neoplastic progression is extremely limited. Our objective was to establish a cell culture model for SBOTs and to characterize their phenotype and genotype. We compared cultures derived from two SBOTs, one of which was a short-term culture containing a BRAF mutation but few other cytogenetic changes while the other culture developed into a spontaneously immortalized permanent cell line and had numerical and structural chromosomal abnormalities but lacked RAS/BRAF mutations. Both cultures formed whorl-like epithelial colonies and resembled low-grade invasive carcinomas by their secretion of CA125 and oviduct-specific glycoprotein, production of matrix metalloproteinases, E-cadherin expression, and telomerase activity. Other characteristics associated with neoplastic transformation, including invasiveness, anchorage-independent growth, and tumorigenicity, were not observed. Importantly, cell motility was reduced in both lines, likely contributing to the lack of invasiveness. The results reveal a striking phenotypic similarity between the two cell lines, regardless of their cytogenetic diversity, which suggests that their characteristic phenotype is regulated to a large degree by epigenetic and environmental factors. In conclusion, we have established the first permanent SBOT cell line, which provides a new model to elucidate the undefined relationship of SBOTs to invasive ovarian carcinomas.

Interphase FISH as a new tool in tumor pathology

Interphase FISH (IFISH) analysis is an intriguing molecular cytogenetic approach to study chromosome abnormalities in cancer. IFISH is a high sensitivity technique because of its ability to identify aberrations on a cell-to-cell level. The possibility to perform IFISH on different types of nuclei obtained both from fresh and archived samples, makes this technique an advantageous method to identify specific chromosome aberrations in cancer and correlate them to prognosis and therapy. The aim of this review is to outline the technical aspects, the sensitivity and specificity and the current strategies for employment of IFISH in tumor pathology, and to discuss the enormous range of novel applications.

Genetic alterations of serous borderline tumors of the ovary compared to stage I serous ovarian carcinomas

Borderline tumors of the ovary comprise 10-20% of all epithelial ovarian tumors, and are placed between clearly benign and obviously malignant ovarian tumors. The issue of whether borderline tumors are precursors of invasive carcinoma or distinct clinical entities, however, is still the subject of discussion. To increase our understanding in relation to this issue, the aim of our study was to analyze both serous borderline and invasive ovarian tumors, and to investigate early carcinogenesis in serous ovarian tumors. Using comparative genomic hybridization, we compared cytogenetic changes in borderline ovarian tumors and stage I invasive tumors. The average number of genetic alterations differed significantly between the borderline and the invasive tumors (1.9 and 9.2, respectively). The most common genetic alterations among the borderline tumors were loss of chromosome 17, 20q, and 18p, and gain of 12p13 approximately q23. These changes were also found among the invasive tumors in a similar percentage. In conclusion, we found four distinct cytogenetic alterations that might be early events in serous ovarian tumors, and that might also characterize a subgroup of borderline ovarian tumors that may have the potential to progress and develop malignancy.

A novel immunohistochemical method for estimating cell cycle phase distribution in ovarian serous neoplasms: implications for the histopathological assessment of paraffin-embedded specimens

We have investigated whether immunohistochemical markers can identify differences in cell cycle phase distribution in ovarian serous neoplasms, including borderline tumours of different grades. Sections of normal ovary (n=18), serous cystadenoma (n=21), borderline serous tumours (n=21) and serous cystadenocarcinoma (n=15) were analysed by immunohistochemistry using markers of cell cycle entry (Mcm-2) and cell cycle phase, including cyclin D1 (mid-to-late G1), cyclin A (S phase), cyclin B1 (G2 phase) and phosphohistone H3 (mitosis). Double-labelling confocal microscopy confirmed marker phase specificity and phase estimations were corroborated by flow cytometry. On progression from normal ovary through serous cystadenoma and borderline tumours to cystadenocarcinomas, expression of Mcm-2 (P<0.0001), cyclin D1 (P=0.002), cyclin A (P<0.0001), cyclin B1 (P<0.0001) and phosphohistone H3 (P<0.0001) increased, paralleled by an increase in the S-phase fraction (cyclin A : Mcm-2 ratio; P=0.002). Borderline tumours of increasing grade also showed increased Mcm-2 and cyclin A expression, together with an increase in the S-phase fraction. Immunohistochemistry can be used to estimate cell cycle phase distribution in ovarian serous neoplasms, giving results similar to flow cytometric analysis and enabling direct assessment of tumour heterogeneity. Immunohistochemical estimates of the S-phase fraction may identify serous borderline tumours likely to exhibit malignant progression and/or select serous cystadenocarcinomas likely to respond to adjuvant therapy.