606 Epidermal growth factor modulation of CXCL10 in keratinocytes and cutaneous cancers

Background Epidermal growth factor (EGF) signaling has well-established roles in cellular proliferation in normal tissue homeostasis and tumorigenesis. EGF receptor inhibitor therapy is associated with the development of a papulopustular rash and other cutaneous inflammatory effects.1 2 These dose-dependent toxicities are linked to treatment response and survival, and may reflect the interplay between EGF and the immune response.3 4 However, the effects of EGF signaling on inflammation in the skin and elsewhere are not entirely understood.5 6 In this study, we aimed to elucidate the immunomodulatory role of EGF in human keratinocytes exposed to the proinflammatory cytokine interferon-γ (IFN-γ). Methods Human keratinocyte cell lines (HaCaT) were exposed to IFN-γ, EGF, or both (48 hours). Differential gene expression analyses of RNA expression was performed using DESeq2.7 Fold change in gene expression on the log2 scale were calculated for each experimental treatment group relative to control. Web Gestalt was used to identify differentially expressed biologic pathways and gene networks, and further investigated in publicly available cutaneous squamous cell (cSCC) cell lines (GSE98767) and cSCC and basal cell carcinoma (BCC) tumor samples (GSE125285).8 Results As compared to untreated control cells, 2792 genes were differentially expressed following IFN-γ treatment, 938 following EGF treatment, and 1248 following the combination of IFN-γ and EGF (figure 1). To assess the impact of EGF on the cellular response to IFN-g, we identified IFN-g-induced genes whose expression was significantly altered by EGF (figure 2). We found that the induction of CXCL10 by IFN-g was among those significantly attenuated in the presence of EGF (padjusted= 0.01) and selected CXCL10 as a model to further define the impact of EGF on immune gene expression. We found that in cutaneous SCC (cSCC) cell lines as well as cSCC and basal cell carcinoma tumor samples, the correlation between IFN-γ and CXCL10 expression was abrogated in samples with higher EGF expression (figure 3). Conclusions EGF has pleotropic roles in cancer including immunologic effects relevant to anti-tumor immunity. These studies demonstrate that EGF alters the transcriptional response to IFN-g including the induction of CXCL10 by IFN-g. Moreover, these studies suggest that in the setting of high EGF levels, there is a modulation of IFN-g-regulated chemokine expression. Further research is needed to clarify the role of EGF in modulating inflammation, and to understand this process in the pathogenesis of EGF receptor inhibitor-induced cutaneous toxicities and skin cancers. Acknowledgements Emory Integrated Genomics Core References Annunziata MC, De Stefano A, Fabbrocini G, Leo S, Marchetti P, Romano MC and Romano I. ‘Current Recommendations and novel strategies for the management of skin toxicities related to Anti-EGFR therapies in patients with metastatic colorectal cancer.’Clin Drug Investig 2019. 39(9): 825–834. Hu JC, Sadeghi P, Pinter-Brown LC, Yashar S and Chiu MW. ‘Cutaneous side effects of epidermal growth factor receptor inhibitors: clinical presentation, pathogenesis, and management.’J Am Acad Dermatol 2007;56(2): 317–326. Lacouture ME ( 2006). ‘Mechanisms of cutaneous toxicities to EGFR inhibitors.’Nat Rev Cancer6(10):803–812. Liao Y, Wang J, Jaehnig EJ, Shi Z and Zhang B ( 2019). ‘WebGestalt 2019: gene set analysis toolkit with revamped UIs and APIs.’ Nucleic Acids Res 47(W1):W199–W205. Lichtenberger BM, Gerber PA, Holcmann M, Buhren BA, Amberg N, Smolle V, Schrumpf H, Boelke E, Ansari P, Mackenzie C, Wollenberg A, Kislat A, Fischer JW, Rock K, Harder J, Schroder JM, Homey B and Sibilia M. ‘Epidermal EGFR controls cutaneous host defense and prevents inflammation.’Sci Transl Med 2013;5(199):199ra111. Love MI, Huber W and Anders S. ‘Moderated estimation of fold change and dispersion for RNA-seq data with DESeq2.’Genome Biol 2014;15(12):550. Ommori R, Park K, Miyagawa F, Azukizawa H, Kanno M and Asada H. ‘Epidermal growth factor receptor (EGFR) inhibitory monoclonal antibodies and EGFR tyrosine kinase inhibitors have distinct effects on the keratinocyte innate immune response.’Br J Dermatol 2018;178(3): 796–797. Tan EH and Chan A. ‘Evidence-based treatment options for the management of skin toxicities associated with epidermal growth factor receptor inhibitors.’Ann Pharmacother 2009;43(10): 1658–1666.