Abstract 3276: Damage-associated molecular pattern (DAMP) induction by 15-deoxy, Δ12,14-prostaglandin J2-ethanolamide: Examination of tumor selectivity, dendritic cell activation and oxidative stress in melanoma

Abstract

Abstract Melanoma is the most lethal form of skin cancer in the United States. Current trends show that melanoma incidence has been increasing for the last 30 years. Chemotherapeutic agents for advanced stage metastatic melanoma have limited efficacy. Although the use of immune-modulating agents such as checkpoint inhibitors has significantly improved therapeutic outcomes, these agents can cause life-threatening autoimmune side effects. Therefore, immunotherapeutic agents that can preferentially eliminate melanoma cells are needed. Agents that induce the release of damage-associated molecular patterns (DAMPs) can stimulate antitumor immunity. DAMPs are produced by damaged or dying cancer cells and include signals such as expression of cell surface calreticulin (ecto-CRT) and the secretion of ATP. DAMPs can recruit and activate immune cells such as dendritic cells which in turn stimulate tumor-specific cytotoxic T cells to kill cancer cells in a process referred to as immunogenic cell death. The elicitation of DAMPs depends on endoplasmic reticulum stress (ER) and oxidative stress. Our group found that our patented agent, 15-deoxy, Δ12,14-prostaglandin J2-ethanolamide (15dPMJ2), inhibits melanoma tumor growth. In addition, 15dPMJ2 induces DAMPs in melanoma cells via an ER stress dependent mechanism. The purpose of this study was to investigate the selectivity of DAMP induction in melanoma by 15dPMJ2, the effect of 15dPMJ2-treated cells on the activation of bone marrow-derived dendritic cells (BMDCs) and the role of oxidative stress in this process. To determine if 15dPMJ2 causes tumor-selective activation of BMDCs, we first examined ecto-CRT and the release of ATP in B16F10 melanoma cells and Melan-A non-tumorigenic melanocytes. Our results showed that 15dPMJ2 significantly increased DAMP expression in tumorigenic compared to non-tumorigenic melanocytes. Importantly, we found that 15dPMJ2-treated B16F10 cells induced maturation of BMDCs as manifested by an increase in the expression of MHCII, CD80 and CD86. However, 15dPMJ2-treated Melan-A cells did not activate BMDCs. In this study, we also tested the role of oxidative stress in 15dPMJ2-induced DAMPs. Our results showed that the antioxidant Trolox significantly decreased 15dPMJ2 induced ecto-CRT and ATP release in B16F10 cells. However, Trolox did not inhibit the activation of BMDCs by 15dPMJ2-treated B16F10 cells. These results suggest that oxidative stress plays an important role in 15dPMJ2-induced DAMPs, but it is not required for the BMDC activation. In conclusion, 15dPMJ2can selectively induce DAMPs in melanoma which results in the activation of BMDCs. Hence, 15dPMJ2 is a potential small molecule immunotherapeutic for melanoma. Citation Format: Ahmed Elhassanny, Rene Escobedo, Daniel Ladin, Rukiyah Van Dross. Damage-associated molecular pattern (DAMP) induction by 15-deoxy, Δ12,14-prostaglandin J2-ethanolamide: Examination of tumor selectivity, dendritic cell activation and oxidative stress in melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3276.