Gene expression in IGROV1 SP and non-SP cells

Side populations have recently been identified in ovarian cancers and may play an important role in post treatment relapse and resistance to chemotherapeutic drugs. In this study, we aimed to identify the differential expression between IGROV1 SP and NSP on Affymetrix HG-U133plus2 microarrays. We found ovarian tumour SP cells frequently over-express the multi-drug resistance associated P-glycoprotein (ABCB1) by Rank Product (FDR<0.05), and by geneset enrichment analysis, embryonic stem cell-associated ‘NOS’ signature (Notch/Oct4/Sox2 regulated genes) and Polycomb Repressive Complex 2 (PRC2) genes were over-expressed, while PRC2-repressed target genes were significantly under-expressed in the SP from ovarian cell lines compared to non-SP (FDR<10-4). Cells were isolated using Hoechst 33342 cell sorting without other treatment. The experiment was carried out in triplicates: 3 SP samples and 3 non-SP samples