43 rd Congress of the International Society of Paediatric Oncology (SIOP) 2011 Auckland, New Zealand, 28 th –30 th October, 2011, SIOP Abstracts

Purpose: The subgroup of High-risk acute lymphoblastic leukemia (ALL) remains one of the greatest challenges in pediatric oncology. Current treatments are still based on chemotherapy whose mechanism of action is non specific and which has a narrow therapeutic index. \udThe LSA-rMnSOD, is an isoform of MnSOD secreted by liposarcoma cells and produced as recombinant form, showing an oncosuppressive action in some cancer cells. In this study, we have investigadet a potential imbalance in pro survival signaling at diagnosis and after rMnSOD treatment on both B and T leukemic cells of high-risk pediatric patients to define the mechanisms underlying the semi-autonomous proliferation leading to leukemia.\udMethod: Lymphoblastic cells, cultured in RPMI medium, supplemented with 1% PEN STREP and 10% BSA, at 370 C were treated for 5 hours with rMnSOD. The internalization of the rMnSOD (scalar concentrations tested: 20-0.2 μg/μL,), in leukemic cells, was demonstrated by the immunocytochemistry at light and electron microscopy. Proliferation tests (MTT and Tripan Blue assay) and western blot were used to evaluate the modulation of proteins (Bcl-2, Bax, AKT,pAKT, ERK, and pERK) after treatment.\udResults: Optical and electronic observations confirmed , in the samples treated with 2 μg/mL, the early signs of apoptosis such as an initial nuclear and cytoplasmic fragmentation, major modulation of proapoptotic Bax and a negative modulation of anti apoptotic Bcl2. Conversly, we observed in ALL B-HR a down phosphorylation of AKT and ERK respect to diagnosis with a decrease in proliferation (MTT= 27%) In ALL T-HR none variation was observed after treatment. \udConclusion: rMnSOD could be an innovative anti-cancer drug expecially for the treatment of high-risk leukemia in emerging target therapies because of its action in pro survival signaling