Abstract A15: IFN-gamma-inducible-protein-10 stimulates intratumoral infiltration of adoptively transferred human NK cells in a melanoma xenograft mouse model.
Authors: Wennerberg Erik , Kremer Veronika , Lundqvist Andreas 
Published: August 2014

Abstract
Aim: In the present study, we investigated whether adoptively transferred human NK cells would migrate towards IP-10 producing melanoma tumors in a xenograft mouse model. Moreover, we assessed the effect of the chemotherapeutic agent doxorubicin in increasing the sensitivity of IFNγ-treated tumors to NK cell lysis in vitro and in vivo.
Background: Adoptive transfer of natural killer (NK) cells is being increasingly used in the treatment of cancer. However, clinical trials involving adoptive transfer of NK cells have to date been more successful against leukemia and other blood-borne cancers than against solid tumors. Several groups have reported that intratumoral infiltration of NK cells correlates with improved prognosis in patients with solid tumors. Recruitment and infiltration and of NK cells in the tumor is dependent on the production of IFN-gamma-inducible-protein-10 (IP-10) by tumor cells. Although tumor cells can be triggered to produce IP-10 by IFNγ stimulation, the expression of MHC class I is increased on tumor cells resulting in decreased sensitivity to NK cell lysis.
Results: Following activation with IL-2, human NK cells upregulated the chemokine receptor CXCR3 resulting in significantly increased migration toward recombinant IP-10, MIG and I-TAC in a transwell migration assay (p=0.03). Expanded NK cells also migrated toward melanoma tumor cells that had been stimulated with IFNγ to induce secretion of IP-10 (p&lt;0.01). In an in vivo xenograft model, an increased accumulation of adoptively infused human NK cells could be detected in subcutaneous melanoma tumors transfected with IP-10 while IP-10 negative tumors had little or no NK cell infiltration (p=0.02). Following infusion of expanded NK cells, significantly reduced tumor burden (p=0.02) and prolonged survival was observed in mice bearing IP-10 positive tumors than mice bearing IP-10 negative tumors (p=0.03). We found that in mice bearing subcutaneous melanoma tumors, intratumoral injections of IFNγ triggered IP-10 production, as confirmed by protein analysis of tumor lysates. Mice that received intravenous injections of doxorubicin prior to IFNγ-injections and adoptive transfer of NK cells had a slower tumor progression than mice that received IFNγ alone prior to NK cell transfer.
Conclusion: Secretion of IP-10 from melanoma tumors stimulates intratumoral infiltration of adoptively transferred NK cells, demonstrating the importance of IP-10/CXCR3 signaling in recruitment of NK cells to solid tumors. Intratumoral IFNγ-treatment of tumors triggers an increased local production of IP-10. Pretreatment of tumor cells with doxorubicin can offset INFγ-induced resistance to NK cell lysis in vitro and in vivo.
Citation Format: Erik Wennerberg, Veronika Kremer, Andreas Lundqvist. IFN-gamma-inducible-protein-10 stimulates intratumoral infiltration of adoptively transferred human NK cells in a melanoma xenograft mouse model. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr A15.