Dataset Information

Gene expression profiling of epithelial ovarian tumours correlated with malignant potential.

ABSTRACT:

Background

Epithelial ovarian tumours exhibit a range of malignant potential, presenting distinct clinical phenotypes. Improved knowledge of gene expression changes and functional pathways associated with these clinical phenotypes may lead to new treatment targets, markers for early detection and a better understanding of disease progression.

Results

Gene expression profiling (Affymetrix, U95Av2) was carried out on 18 ovarian tumours including benign adenomas, borderline adenocarcinomas of low malignant potential and malignant adenocarcinomas. Clustering the expression profiles of samples from patients not treated with chemotherapy prior to surgery effectively classified 92% of samples into their proper histopathological group. Some cancer samples from patients treated with chemotherapy prior to surgery clustered with the benign adenomas. Chemotherapy patients whose tumours exhibited benign-like expression patterns remained disease free for the duration of this study as indicated by continued normal serum CA-125 levels. Statistical analysis identified 163 differentially expressed genes: 61 genes under-expressed in cancer and 102 genes over-expressed in cancer. Profiling the functional categories of co-ordinately expressed genes within this list revealed significant correlation between increased malignant potential and loss of both IGF binding proteins and cell adhesion molecules. Interestingly, in several instances co-ordinately expressed genes sharing biological function also shared chromosomal location.

Conclusion

Our findings indicate that gene expression profiling can reliably distinguish between benign and malignant ovarian tumours. Expression profiles of samples from patients pre-treated with chemotherapy may be useful in predicting disease free survival and the likelihood of recurrence. Loss of expression of IGF binding proteins as well as specific cell adhesion molecules may be a significant mechanism of disease progression in ovarian cancer. Expression levels in borderline tumours were intermediate between benign adenomas and malignant adenocarcinomas for a significant portion of the differentially expressed genes, suggesting that borderline tumours are a transitional state between benign and malignant tumours. Finally, genes displaying coordinated changes in gene expression were often genetically linked, suggesting that changes in expression for these genes are the consequence of regional duplications, deletions or epigenetic events.

SUBMITTER: Warrenfeltz S

PROVIDER: S-EPMC524500 | biostudies-literature | 2004 Oct

REPOSITORIES: biostudies-literature

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Publications

Gene expression profiling of epithelial ovarian tumours correlated with malignant potential.

Warrenfeltz Susanne S Pavlik Stephen S Datta Susmita S Kraemer Eileen T ET Benigno Benedict B McDonald John F JF

Molecular cancer 20041007

<h4>Background</h4>Epithelial ovarian tumours exhibit a range of malignant potential, presenting distinct clinical phenotypes. Improved knowledge of gene expression changes and functional pathways associated with these clinical phenotypes may lead to new treatment targets, markers for early detection and a better understanding of disease progression.<h4>Results</h4>Gene expression profiling (Affymetrix, U95Av2) was carried out on 18 ovarian tumours including benign adenomas, borderline adenocarc ...[more]

PMID: 15471544

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Project description:Ovarian tumors of low malignant potential and low-grade ovarian serous carcinomas are thought to represent different stages on a tumorigenic continuum and to develop along pathways distinct from high-grade ovarian serous carcinoma. We performed gene expression profiling on three normal human ovarian surface epithelia samples, and 10 low-grade and 10 high-grade ovarian serous carcinomas. Analysis of gene expression profiles of these samples has identified 80 genes upregulated and 232 genes downregulated in low-grade ovarian serous carcinomas. PAX2 was found to be one of the most upregulated genes in low-grade ovarian serous carcinoma. The upregulation of PAX2 was validated by real-time quantitative RT-PCR, western blot and immunohistochemical analyses. Real-time RT-PCR showed a statistically significant difference in PAX2 mRNA expression (expressed as fold change in comparison to normal human ovarian surface epithelia) among ovarian tumors of low malignant potential (1837.38, N=8), low-grade (183.12, N=17), and high-grade (3.72, N=23) carcinoma samples (P=0.015). Western blot analysis revealed strong PAX2 expression in ovarian tumors of low malignant potential (67%, N=3) and low-grade carcinoma samples (50%, N=10) but no PAX2 protein expression in high-grade carcinomas (0%, N=10). Using immunohistochemistry, tumors of low malignant potential (59%, N=17) and low-grade carcinoma (63%, N=16) samples expressed significantly stronger nuclear staining than high-grade ovarian carcinoma samples (9.1%, N=263). Furthermore, consistent with earlier immunohistochemical findings, PAX2 expression was expressed in the epithelial cells of fallopian tubes but not in normal ovarian surface epithelial cells. Our findings further support the two-tiered hypothesis that tumors of low malignant potential and low-grade ovarian serous carcinoma are on a continuum and are distinct from high-grade ovarian carcinomas. In addition, the absence of PAX2 expression in normal ovarian epithelia but expression in fallopian tube fimbria and ciliated epithelial inclusions would suggest the potential development of tumors of low malignant potential and of low-grade ovarian serous carcinomas from secondary Müllerian structures.

Dataset Information

Gene expression profiling of epithelial ovarian tumours correlated with malignant potential.

Background

Results

Conclusion

Publications

Gene expression profiling of epithelial ovarian tumours correlated with malignant potential.

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