Aldehyde dehydrogenase activity in serous ovarian carcinoma.

e15577 Background: Only specific subpopulations of tumor cells, so called cancer stem cells (CSC) may initiate and maintain tumors. The phenotype and molecular properties of ovarian CSC remain elusive. Aldehyde dehydrogenase (ALDH) activity characterizes (cancer) stem cells in different tissues and has been associated with ovarian CSC (Silva et al, 2011; Kryczek et al, 2012). Contradictory results have been reported on ALDH1 expression and prognosis in ovarian carcinoma. In this study, we explore the role of ALDH in serous ovarian carcinoma (SOC). Methods: Aldefluor-staining was used to assess ALDH activity in different ovarian carcinoma cell-lines and patient samples. ALDH+ and ALDH- cells isolated by FACS and ALDH1 versus control siRNA treated cells were analyzed in sphere forming, proliferation, BrdU and cell cycle assays. In vivo tumorigenicity assays including serial re-transplantations were performed in NOD/SCID/IL2Rγnull mice. ALDH1 and Ki67 expression were assessed immunohistochemically on a tissu...