Abstract 4050: Association of long term NK cell culture and TIMP3 over-expression with NK cell reduced susceptibility to leukemia and epithelial cancer cell induced damage

Allogeneic leukemia and cancer epithelial (CE) cells have been recently shown to induce,in vitro, NK cell abnormalities (NKCA). The latter include NK cell depletion and apoptosis as well as natural cytotoxic receptor (NCR) CD16 down-regulation. The potential negative impact of leukemia and CE cell induced NKCAs on the in vivo anti-tumor activity of NK cells and the limited information about strategies to protect NK cells from NKCAs have prompted us to characterize NKCAs and to develop strategies to counteract them. NKCA induction by leukemia and CE cells is influenced neither by interleukin-2 (IL-2) treatment nor by HLA class I antigen expression, but is abrogated by a long term culture of peripheral blood mononuclear cells (PBMCs) at 37 ºC. Following a 10 day culture of PBMCs, NK cells become resistant to cancer cell induced NKCA but maintain their cytotoxic activity. Actinomycin D restores the susceptibility of long term NK (LTNK) cells to NKCAs suggesting that the generation of resistance to NKCAs requires RNA transcription. TAPI-0, a functional analogue of the tissue inhibitor of metalloproteinases (TIMP) 3, inhibits cancer cell induced NKCAs indicating a role for a restricted number of metalloproteinases (MMPs) in the generation of this phenomenon. This conclusion is supported by the reduced susceptibility to cancer cell induced NKCAs of LTNK cells in which TIMP3 gene and protein are over-expressed. Finally, subcutaneous infusion of IL-2 stimulated LTNK cells inhibited subcutaneous growth of the monoblastic leukemia cells, ML-2 in CB17scid mice while short term, IL-2 stimulated NK cells did not suggesting that LTNK cells have significant anti-leukemia capacity in vivo. This information may contribute to the rational design of targeted strategies to enhance the efficacy of NK cell-based-immunotherapy for the treatment of myeloid leukemias with haploidentical or allogeneic NK cells. Citation Format: Giuseppe Sconocchia, Roberto Arriga, Sara Caratelli, Giulia Lanzilli, Andrea Coppola, Giulio C. Spagnoli, Adriano Venditti, Sergio Amadori, Davide Lauro, Maria I. Del Principe, Luca Maurillo, Francesco Buccisano, Barbara Capuani, Xinhui Wang, Soldano Ferrone. Association of long term NK cell culture and TIMP3 over-expression with NK cell reduced susceptibility to leukemia and epithelial cancer cell induced damage. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philade