About 10%-20% of patients with abdominal cancers develop malignant ascites (MA), which is in general associated with a worse outcome and cell clusters called spheroids are believed to facilitate metastasis in ovarian cancer. The abnormal accumulation of fluid within the peritoneal cavity is caused by increased vascular permeability and/or obstructed lymphatic drainage. The ascites can be easily drained from the peritoneal cavity (paracentesis) for further analysis. It contains a complex heterogenous mixture of resident and non-resident cells such as tumour cells, stromal cells, cancer-associated fibroblast, red and white blood cells. Numerous studies have highlighted increased concentrations of cytokines such as IL-6, IL-10, and vascular endothelial growth factor (VEGF-A), as well as elevated levels of triglycerides, amylase and alkaline phosphatase when compared to serum.
We performed a comparative proteomics analysis of 3 depleted patient derived malignant ascites samples and detected more than 600 proteins. Pathway analysis revealed upregulation of ECM-receptor and proteoglycans in cancer pathways when compared to a depleted control serum sample. Cells grown in ascites showed >1.5-fold increased viability (p<0.05), when compared to cells grown in tissue culture medium alone, indicating the significant impact of ascites on cell proliferation. Next, we analysed the proteome of two ovarian cancer cell lines grown in 2D and 3D in tissue culture medium when compared to ascites to elucidate the molecular changes associated with the observed viability advantage. In addition, proteins unique to cells cultured in patient ascites fluid were identified and are investigated for the role in regulating morphology and viability of spheroids. Patient derived spheroids are an important tool and the identification of soluble factors to facilitate spheroid culture in vitro might be of interest to many.