Abstract 1961: Embryonic stem cells antigens: expression in acute myeloid leukemia cells

Abstract

Abstract Acute Myeloid Leukemia (AML) is characterized by the expansion and resistance to apoptosis of myeloid cells blocked in early stages of differentiation. A subset of stem or progenitor cells, termed leukemic stem cells (LSC), which retain or reacquire self-renewing properties, as well as the capacity to remain in a poorly differentiated stage, give rise to the leukemic clone. The identification and purification of the LSC can provide a powerful tool for diagnosis, prognosis and therapy. Several studies suggested that LSC belong to the CD34+ CD38- compartment. Self-renewal and lack of differentiation are properties of embryonic and induced pluripotent stem cell which specifically express a set of differentiation antigens (SSEA1 and SSEA3) and transcription factors (OCT¾, SOX2, and NANOG), designated as ESCA. We postulate that an epigenetic reprogramming could induce the ESCA expression on HSC. The aim of our study was to investigate the expression ESCA in the CD34+CD38- cells from normal bone marrow (NBM) and from 50 AML BM patients. Then compare ESCA's expression between CD34+CD38- and CD34+CD38+ cells. We studied the expression in 5 cell lines (NTERA-2 which is control cell line, KG1a, U937, THP-1 and HL60 leukemic cell lines) and their potential involvement in myeloid differentiation in 2 cell lines (HL60 and THP-1). Thereafter, we inhibited the expression of ESCA in 3 leukemic cell lines (HL60, KG1a and U937) to better understand their role in abnormal proliferation or differentiation. The preliminary experiments showed an important expression of ESCA on all 5 cell lines by Multicolor Flow Cytometry (MFC), confirmed by RT-PCR. Then, we compared the expression of ESCA in CD34+CD38- cells between normal and leukemic marrow. We observed an up-regulation of two transcription factors OCT3/4 and SOX2 and the protein SSEA3 with 2-fold higher expression in AML cells compared to normal HSC. In addition, we found the down regulation of SSEA1 protein involved in cell adhesion, migration and differentiation. We also compared the expression of ESCA between the CD34+CD38- and CD34+CD38+ AML population. We observed a higher expression of OCT3/4 and SSEA3 (1.3-fold) in CD34+CD38-. We found a higher expression of SSEA1 (1.9-fold), NANOG and SOX2 (1.2-fold) in AML CD34+CD38+ population compared to CD34+CD38- population. We investigated whether there was a relationship between the overexpression of ESCA and a cytogenetic subgroup of AML. We found that AML t(15;17) expressed OCT3/4 at higher level than the other ESCA. Finally, the inhibition experiments showed that Oct3/4 was strongly inhibited in the KG1a cell line. In conclusion, these results suggest that the deregulation of ESCA may have a potential role in leukemogenesis by maintaining the LSC properties. This prompts us to test the relevance of these markers for LSC identification and as therapeutic strategies. Citation Format: Lydia Campos, TIPHANIE PICOT, CARMEN AANEI, PASCALE FLANDRIN-GRESTA, EMMANUELLE TAVERNIER, DENIS GUYOTAT. Embryonic stem cells antigens: expression in acute myeloid leukemia cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1961. doi:10.1158/1538-7445.AM2014-1961