Rewired Signaling at the Nexus of Melanoma Metastasis and Resistance - Summary This R35 focuses on novel mechanisms underlying control of key UPR components that impact melanoma metastasis in aged rather than young mice by (i) tumor-intrinsic mechanisms (NRF2, ATF4) implicated in resistance or sensitivity to therapy, and (ii) tumor-extrinsic mechanisms that define intestinal microbiota composition and impact anti-tumor immunity. This OIA application leverages discoveries made during our R35 support period, which enabled us to define the regulation and function of ATF4, one of the main UPR signaling components, in pro- and anti-apoptotic signaling. Several fundamental discoveries will be pursued. (1) the effect of aging on altered metabolic signaling, as exemplified by effects of asparagine synthase (ASNS) and glutaryl- CoA dehydrogenase (GCDH) on ATF4. Specifically, while ASNS inhibition promotes melanoma resistance to therapy, GCDH inhibition causes melanoma cell death, although both phenotypes are ATF4-dependent. (2) the effect of aging on gut microbiota composition with concomitant impact on the degree of anti-tumor immunity and tumor propensity to metastasize. Among fundamental questions we will address are: (i) What confers ATF4 pro- apoptotic vs. anti-apoptotic activities and how are these affected during aging (ii) How do gut microbiota, and changes in bacterial commensals that occur with aging, impact anti-tumor immunity and tumor metastasis? (iii) Could ATF4 inhibition (through targeting some of its modulators) be used as a novel strategy to enhance tumor sensitization to therapy in young and aged animals? To answer these questions, we will employ innovative technologies, including conditional knock-out mice, CRISPR-Cas9 technology, single-cell RNAseq, spatial transcriptomics, metabolomics, and computational approaches. Models of young (2 months) and aged (12-15 months = 55–70-year-old human) mice will be used to define mechanisms underlying how a key UPR signaling component, ATF4, impacts melanoma metastasis mechanisms. In all, these studies should reveal novel paradigms in melanoma biology impacting metastasis under relevant physiological conditions.
