A method and server for predicting damaging missense mutations. Nat Methods 2010;7: 248e9.

Vitiligo is an autoimmune skin disease caused by cutaneous melanocyte loss. Although phototherapy and T cell suppression therapy have been widely used to induce epidermal re-pigmentation, full pigmentation recovery is rarely achieved due to our poor understanding of the cellular and molecular mechanisms governing this process. Here, we identify unique melanocyte stem cell (McSC) epidermal migration rates between male and female mice, which is due to sexually dimorphic cutaneous inflammatory responses generated by ultra-violet B exposure. Using genetically engineered mouse models, and unbiased bulk and single-cell mRNA sequencing approaches, we determine that manipulating the inflammatory response through cyclooxygenase and its downstream prostaglandin product regulates McSC proliferation and epidermal migration in response to UVB exposure. Furthermore, we demonstrate that a combinational therapy that manipulates both macrophages and T cells (or innate and adaptive immunity) significantly promotes epidermal melanocyte re-population. With these findings, we propose a novel therapeutic strategy for repigmentation in patients with depigmentation conditions such as vitiligo.

Therapies targeting oncogene addiction have had a tremendous impact on tumor growth and patient outcome, but drug resistance continues to be problematic. One approach to deal with the challenge of resistance entails extending anti-cancer treatments beyond targeting cancer cells by additionally altering the tumor microenvironment. Understanding how the tumor microenvironment contributes to the evolution of diverse resistance pathways could aid in the design of sequential treatments that can elicit and take advantage of a predictable resistance trajectory. Tumor associated macrophages often support neoplastic growth and are frequently the most abundant immune cell found in tumors. Here, we used clinically relevant in vivo Braf-mutant melanoma models with fluorescent markers to track the stage-specific changes in macrophages under targeted therapy with Braf/Mek inhibitors and assessed the dynamic evolution of the macrophage population generated by therapy pressure-induced stress. During the onset of a drug-tolerant persister state, Ccr2+ monocyte-derived macrophage infiltration rose, suggesting that macrophage influx at this point could facilitate the onset of stable drug resistance. Comparison of melanomas that develop in a Ccr2-proficient or deficient microenvironment demonstrated that lack of melanoma infiltrating Ccr2+ macrophages delayed onset of resistance and shifted melanoma cell evolution towards unstable resistance. Unstable resistance was characterized by sensitivity to targeted therapy when factors from the microenvironment were lost. Importantly, this phenotype was reversed by co-culturing melanoma cells with Ccr2+ macrophages. Overall, this study demonstrates that the development of resistance may be directed by altering the tumor microenvironment to improve treatment timing and the probability of relapse.

Therapies targeting oncogene addiction have had a tremendous impact on patient care, but drug resistance continues to be problematic. One method to deal with this challenge entails extending the scope of anti-cancer treatment beyond tumor cells by additionally altering their tumor microenvironment. Understanding how the tumor microenvironment can contribute to the evolution of diverse resistance pathways could aid in the rational design of sequential treatments that enforce pressure towards a more predictable resistance trajectory. Tumor associated macrophages often support neoplastic growth and are frequently the most abundant immune cell found in tumors. Here, we used clinically relevant in vivo Braf-mutant melanoma models and Ccr2-RFP; Cx3cr1-GFP mice to track the long-term changes in tumor cells and macrophages under targeted therapy with Braf/Mek inhibitors. We assessed the dynamic evolution of the macrophage population generated by therapy pressure-induced stress. During the onset of a drug-tolerant persister state, Ccr2+ macrophage infiltration rises, underscoring a prominent role at this point in melanoma evolution for development of drug-resistance. Importantly, we show that a lack of melanoma infiltrating Ccr2+ macrophages delays onset of resistance. In this case, rebounded tumor cells from Ccr2 knockout recipients favor the evolution of cell-extrinsic mediated resistance mechanisms, which can be reversed when these adapted melanoma cells are relocated to a microenvironment with functional Ccr2. Conversely, Ccr2 presence promotes development of cell-intrinsic drug resistance with a stable phenotype in rebounded tumor cells. Overall, this demonstrates that the development of resistance may be manipulated and directed to improve timing and probability of relapse. Citation Format: Dahihm Kim, Luye An, Jiwon Moon, Andrew White. Ccr2+ monocyte derived macrophages influence trajectories of acquired therapy resistance in BRAF-mutant melanoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5950.