Variation in gene expression patterns in effusions and primary tumors from serous ovarian cancer patients

Background: While numerous studies have characterized primary ovarian tumors, little information is available regarding expression patterns of metastatic sites of this cancer. To define sets of genes that distinguish primary and metastatic ovarian tumors, we used cDNA microarrays to characterize global gene expression patterns in 38 effusions ( 28 peritoneal, 10 pleural) and 8 corresponding primary ovarian tumors, and searched for associations between expression patterns and clinical parameters. Results: We observed multidimensional variation in expression patterns among the cancers. Coordinate variation in expression of genes from two chromosomal regions, 8q and 19q, was seen in subsets of the cancers indicating possible amplifications in these regions. A set of 112 unique genes of known function was differentially expressed between primary tumors and effusions using supervised analysis. Relatively few differences were seen between effusions isolated from the pleural and peritoneal cavities or between effusions from patients diagnosed with stage III and stage IV cancers. A set of 84 unique genes was identified that distinguished high from lower grade ovarian cancers. The results were corroborated using immunocytochemistry, mRNA in situ hybridization, and immunoblotting. Conclusion: The extensive variation in expression patterns observed underscores the molecular heterogeneity of ovarian cancer, but suggests a similar molecular profile for ovarian carcinoma cells in serosal cavities.