Abstract 5548: Indicators of immune activation upon p14ARF and interferon-beta gene transfer in a human melanoma cell line

Abstract

Abstract Immunoevasion adopted by tumor cells is an important cancer hallmark and understanding of its mechanisms has generated promising therapeutic approaches. In this context, triggering immunogenic cell death (ICD) is a promising idea since it alarms the immune system by attracting a myriad of cell populations that promote innate and adaptive immune responses. Since melanomas preserve wild-type p53 in over 80% of cases, our group developed a gene therapy strategy that utilizes an adenoviral vector with a p53-responsive promoter (PG). Here we present a critical advance for our approach, examining the immune activating potential of combined p14ARF and IFN-beta gene transfer in human melanoma cells. Our results indicate that IFN-beta alone or in combination with p14ARF was able to induce massive cell death accompanied by caspase 3/7 activation in the human melanoma cell line SKMEL147. In our animal model of in situ gene therapy, s.c. SKMEL147 tumors were established in Nod-scid mice before intratumoral virus injection, revealing tumor inhibition and improved survival in response to IFN-beta alone or in combination with p14ARF. However, this model cannot reveal immune activation and so far the benefit of p14ARF has not been revealed. Strikingly, three markers of ICD (exposition of calrecticulin, secretion of ATP and IFN-beta) were induced only when cells were treated with combined p14ARF and IFN-beta gene transfer. We then used PBMCs derived from normal donors as a source of DCs and lymphocytes. Coculture of DCs with previously-transduced SKMEL147 exhibit a typical phenotype of activation. Finally, coculture of these exposed DCs with lymphocytes results in high-level secretion of proinflammatory cytokines, followed by the increase of IL-10 in the samples treated with combination of p14ARF and IFN-beta. Collectively, our results indicate that the advantage of p14ARF and INF-beta delivered by our adenoviral system is the induction of cell death in human melanoma cells by an immune-activating mechanism. Future studies will include examination of this phenomenon in tumors from melanoma patients and using their own PBMCS. In parallel, the use of PDX model for in situ treatment will also be explored. Citation Format: Otto Luiz Cerqueira, Maria Alejandra Salomon, Elaine Cristina Cardoso, Tharcisio Citrangulo Tortelli, Bryan Eric Strauss. Indicators of immune activation upon p14ARF and interferon-beta gene transfer in a human melanoma cell line [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5548.