Proteome profiles of paired ovarian cancer ascites before and after chemotherapy

Ovarian cancer is characterized by transcoelomic metastasis into the peritoneal cavity. The peritoneal malignant ascites is enriched with ovarian cancer cells and a small amount of tumor-associated immune cells which create a unique microenvironment actively contributing to progression of the disease. However, it is remain unclear how cancer cells communicate to its local environment under the influence of chemotherapy. To address this issue, we performed LC-MS/MS analyses of ovarian cancer ascites from the same patients before and after chemotherapy. We found that neoadjuvant chemotherapy causes a significant changes in the composition of ascites, and these changes are similar in samples obtained from all patients (n=10). Functional annotation of upregulated proteins with the use of KEGG and GO databases revealed that malignant ascites after chemotherapy were enriched with the cluster of spliceosomal proteins. These splicing factors were linked to induction of epithelial-to-mesenchymal transition leading to a more aggressive phenotype of cancer cells.