1205 Vitiligo lesional and non-lesional skin shows polar cytokine activation J Ruano 1 , AB Pavel 2 , RD Sanyal 2 , J Gay-Mimbrera 1 , N Zhang 2 , YD Estrada 2 and E Guttman-Yassky 2 1 IMIBIC/Reina Sofı´a University Hospital, Co´rdoba, Spain and 2 Mount Sinai, New York, NY Vitiligo is a chronic autoimmune depigmentation disorder affecting up to 152 million people worldwide, with increased prevalence among skin of color individuals in whom the disease is more noticeable. It has a profound negative impact on patient quality of life and lacks effective therapeutic options. While the current pathogenic paradigm highlights T H 1/IFNg- upregulation, limited blood data also suggests possible involvement of other cytokine axes. We sought to investigate the genomic profile in lesional and non-lesional tissues of patients with vitiligo (n¼16) as compared with control skin (n¼8). We found significant upregulation of multiple immune pathways in both lesional and non-lesional vitiligo skin versus controls. These included significant increases in T H 1 markers (i.e. IFNg, CXCL9, CXCL10, and CCL5; p<0.01), but also in key T H 2 cytokines and chemokines (i.e. IL-5, IL-13; p<0.05, CCL13, and CCL18; p<0.01). Less consistent and significant increases were detected in some T H 17/T H 22 markers (i.e. IL-17A, IL-22, and S100A9; p<0.05), mostly in lesional skin only. Key mediators of JAK/STAT signaling (JAK3, STAT1) were significantlyupregulated in both lesional and non- lesional tissues, as was the general inflammation marker MMP12 (p<0.05 for all). Overall, our data expands the current understanding of cytokine pathways in vitiligo skin beyond T H 1 skewing, providing a basis for possible future therapeutic targeting for patients with vitiligo. 1206 Aspirin inhibits melanoma cell motility through suppression of PGE 2 and activation of AMPK D Kumar 1 , H Rahman 1 and D Grossman 2 1 Huntsman Cancer Institute, Salt Lake City, UT and 2 Dermatology, University of Utah, Salt Lake City, UT Chronic aspirin (ASA) use may reduce melanoma risk in humans. We investigated the po- tential anti-melanoma effects of ASA in a panel of melanoma and transformed melanocyte cell lines, and in a preclinical model. ASA (1 mM) and Celecoxib (20 mM) did not affect cell proliferation, but each significantly reduced motility in transwell assays. ASA-mediated in- hibition of cell migration was rescued by exogenous PGE 2 (1 mM) or Compound C (0.5 mM), which inhibited phosphorylation of adenosine monophosphate-activated protein kinase (AMPK). ASA also inhibited colony formation in agarose, which was rescued by addition of PGE 2 ; and inhibited production of melanin, which was reversed by Compound C. Following a single dose of ASA (0.4 mg, by gavage), salicylate was detected by mass spectrometry in mouse plasma and skin at 4 h and PGE 2 levels remained depressed in these samples for up to 24 h. Human melanoma xenografts MTG2 (NRas-Q61R) and MTG4 (BRaf-V600E) grew significantly more slowly in NOD-SCID mice receiving daily ASA compared to control mice. By contrast, growth of A375 (BRaf-V600E) and WM3311 tumors was not affected by ASA. ASA-sensitive (MTG2, MTG4) but not ASA-resistant (A375) tumors from ASA-treated mice displayed reduced proliferation compared to tumors from control mice, while there was no difference in apoptotic rate. ASA-treated mice bearing MTG2 and A375 tumors had decreased PGE 2 in plasma and tumors and increased tumor expression of phosphorylated AMPK. ASA also inhibited growth of established MTG2 tumors, and was associated with increased plasma interleukin (IL)-5 and IL-28, and decreased plasma IL-3 and interferon-g. We conclude that ASA inhibits melanoma cell motility, colony formation, and pigmentation through suppression of PGE 2 and activation of AMPK, and that daily oral ASA suppresses PGE 2 in mouse blood, skin and tumors, and alters cytokine profiles. However, these activities were not sufficient for ASA to inhibit growth of some melanoma tumors in vivo. 1207 RNF4 ubiquitin ligase drives melanoma progression E Avitan-Hersh 1 , Y Feng 2 , Y Zohar 3 , T Zhang 4 , K Brown 4 , R Bergman 5 , ZA Ronai 2 and A Orian 6 1 Department of Dermatology, Rambam Health Care Campus, Haifa, Israel, 2 Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 3 Department of Pathology, Rambam Health Care Campus, Haifa, Israel, 4 Laboratory of Translational Genomics, National Cancer Institute, Bethesda, MD, 5 Department of Dermatology, Rambam Health Care Campus, Haifa, Israel and 6 Technion Integrated Cancer Center, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel Deciphering new molecular targets that are crucial for melanoma progression is of utmost importance. One such potential target is RNF4, a SUMO-targeted ubiquitin ligase. In most cases, RNF4-dependent ubiquitination tags SUMOylated proteins for degradation. Addi- tionally, RNF4 enhances the stability & transcriptional activity of selected phospho-onco- proteins, hence promoting tumorigenesis. We aimed to evaluate the contribution of RNF4 to human melanoma progression in culture and in-vivo. We found that RNF4 is essential for melanoma progression and survival. Knockdown of RNF4 attenuated melanoma cell prolif- eration, migration and clonogenicity (p<0.05). Likewise, Conditional expression of RNF4, but not the inactive mutant, promoted tumor growth, resulting in larger and highly vascular xenigrafts (p<0.001). RNA-seq analysis of RNF4-expressing tumors identified a distinct set of 102 genes that were upregulated by RNF4. These genes regulate angiogenesis, migration, and cell growth. Pathway analysis identified the translation machinery as a key node controled by RNF4 in these tumors. Thus, RNF4 directly links translation with protein dynamics during melanoma tumorigenesis. In addition, the potential implications to melanoma patients will be discussed. In conclusion, our results establish a critical role for RNF4 in melanoma tumorigenesis. 1208 Predominance of oral mucosal melanoma within high areas of mechanical stress PH Rambhia 1 , IJ Stojanov 2 and J Arbesman 1 1 Case Western Reserve University School of Medicine, Cleveland, OH and 2 Case Western Reserve University, Cleveland, OH Primary oral mucosal melanoma (POMM) is an aggressive variant of melanoma. Sun expo- sure is considered a causative factor in cutaneous melanoma, but oral melanoma patho- genesis remains obscure, as sun exposure does not readily occur here. Prior reports of POMM have shown that the oral cavity is not uniformly affected but rather there exists a striking predilection for palatal mucosa and attached gingiva overlying the maxilla. Pathophysiology underlying this unique predilection remains unclear. These questions prompted a systematic review of POMM cases to establish a comprehensive anatomical predilection and provide insight into novel candidate risk factors. PRISMA guidelines were used to search MEDLINE, Embase, and Cochrane for POMM cases with specific anatomic location stated. Studies that did not include total number of oral melanoma cases over a defined period of time and whose aim was not a general presentation of oral melanoma cases were not included. Twenty-five studies, totaling 549 POMM cases met inclusion criteria. The maxillary gingiva and hard palatal mucosa were involved in 71.77% (394/549) of cases with sub-site stated, with remaining cases involving the mandibular gingiva and floor of mouth (12.39%), labial mu- cosa/lips (6.19%), buccal mucosa (4.92%), tongue (2.73%), soft palatal mucosa (1.46%) and tonsils (0.55%). These data confirm propensity for oral melanoma involvement of masticatory mucosa overlying the hard palate and maxillary alveolus. Associations between mechanical stress/pressure and plantar melanomas may provide insights into POMM site predilection. Normal mastication conveys stress patterns that are predominantly dispersed through osseous structures attached to the maxillary gingiva and hard palate. The hard palate is additionally subject to repeated mechanical loads from food pressed against it by the tongue and during swallowing. We postulate that mechanical stress may be at least partially responsible for the POMM distribution observed. 1209 Ambient relevant diesel exhaust particles cause skin hyperpigmentation ex vivo and in vivo in human skin: The Du ¨ sseldorf Pollution Patch Test S Grether-Beck 1 , A Marini 1 , T Jaenicke 1 , H Brenden 1 , I Uthe 1 , I Felsner 1 and J Krutmann 2 1 IUF, Duesseldorf, Germany and 2 Institute for Environmental Medicine, Duesseldorf, Germany Epidemiologic studies showed that exposure to traffic-related air pollutants including par- ticulate matter and soot is associated with signs of extrinsic skin aging such as facial pigment spots. Mechanistic evidence directly linking skin exposure to traffic-related air pollutants with skin hyperpigmentation (HP) is lacking. We therefore developed a standardized, robust ex vivo human skin model which allows application of ambient relevant, toxicologically well characterized, traffic-related diesel exhaust particles (DEP) onto the surface of human skin. We found that repetitive topical exposure of these models to DEP at environmentally relevant, non-toxic concentrations increased skin pigmentation. This increase was visible by the bold eye, dose- and time-dependent (chromametry) and associated with increased melanin syn- thesis. Accordingly, in DEP-treated skin, (i) total melanin content and (ii) the number of melanin-positive cells (Fontana-Masson) was significantly increased, and (iii) this was accompanied by an increased transcriptional expression of genes involved in melanin syn- thesis (e.g. MITF, TYR, TRP, DCT). To assess the in vivo relevance we developed the Du ¨s- seldorf Pollution Patch Test. In healthy human volunteers (n¼ 10) repetitive Finn chamber application of DEP at non-toxic concentrations caused a HP response, which was essentially identical to that observed in the ex vivo skin model including the gene expression pattern (n¼4). DEP-induced HP was mediated at least in part by oxidative stress because (i) epidermal antioxidants were depleted (Raman spectroscopy) after DEP application and (ii) increased pigmentation was reduced if DEP-applications were preceded by topical applications of a cosmetic preparation containing antioxidants. These studies establish a direct link between exposure of human skin to traffic-related air pollutants and skin HP. 1210 Enhancing the therapeutic efficacy of immune checkpoint inhibition and targeted therapy using anti-tumor antibodies in mouse melanoma R Perez-Lorenzo 1 , S Erjavec 2 , R Clynes 1 and AM Christiano 3 1 Dermatology, Columbia University, New York, NY, 2 Genetics and Development, Columbia University, New York, NY and 3 Dermatology, and Genetics and Development, Columbia University, New York, NY Antitumor antibodies have made a great clinical impact in combination with chemotherapy, but these regimens do not capitalize on their potential to enhance tumor immunogenicity. Further, no antitumor antibodies have been developed for melanoma, despite evidence for high immunogenicity and immunotherapeutic responsiveness. Antitumor immunity is evident in primary and metastatic melanoma from the presence of high levels of TIL capable of recognizing melanoma-derived antigens, however, potent regulatory signals limit the effector immune re- sponses. To enhance the vaccinal effects of antitumor antibodies while removing suppressive signals, we first tested the combination of antitumor antibodies (TA99; anti-TYRP1) with anti- body-mediated depletion of Treg in B16 mouse melanoma. We found that depletion of Treg in combination with treatment with TA99 resulted in a significant reduction of tumor growth in both subcutaneous and metastatic models, associated with an increase in CD8 + T cells and a strong CD3 + CD137 + infiltrate. Moreover, TA99 also enhanced the therapeutic efficacy of anti- PD-1 and anti-CTLA-4 antibodies, which was associated with a greater CD8 + , NK1.1 + and dendritic cell infiltrate, suggestive of an increased antitumor immune response. Further, we found that MEK inhibitor (MEKi) could be used to increase the expression of melanosomal an- tigens and pigmentation in B16 melanoma cells. Treatment of BRAF WT B16 melanomas with a combination of TA99 and MEKi resulted in a synergistic reduction in tumor growth. Finally, treatment of YUMM melanoma (BRAF V600E ) with TA99/MEKi resulted in the complete elimi- nation of tumors in the majority of animals, and produced durable responses. Taken together, our findings suggest that MEKi induce an increased expression of tumor-associated antigens, and that combination with anti-tumor antibodies generated a more robust adaptive antitumor response sustained by immune checkpoint inhibition therapy in B16 melanoma. Pigmentation and Melanoma | ABSTRACTS www.jidonline.org S205