Journal of Experimental & Clinical Cancer Research · Published 2026-05-14 · DOI 10.1186/s13046-026-03734-2
Irene Fiorilla, Beatrice Ghezzi, Alessia Ponzano, Enrico Moiso, Federica Riccardo, Nicoletta Tommasi, Lidia Avalle, Giovanna Carrà, Filippo Ugolini, Edoardo Calussi, Alberto Maria Todesco, Sabrina Digiovanni, Filippo Casone, Giulia Rizza, Luca Ponzone, Anna Szumera-Ciećkiewicz, Maria Cavaletto, Paolo Ettore Porporato, Laura Conti, Chiara Riganti, Daniela Massi, Enzo Calautti, Valentina Audrito
Abstract Background Metastatic cutaneous melanoma (MCM) is primarily treated with BRAF/MEK inhibitors and immune checkpoint inhibitors (ICIs), but the long-term efficacy of these therapies is often limited by acquired resistance. Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in NAD biosynthesis, is frequently upregulated in MCM, supporting metabolic rewiring and targeted therapy resistance. Interferon-γ (IFN-γ) signaling plays a central role in melanoma biology, exerting both antitumor and immunoregulatory effects, linked with the onset of therapeutic resistance. Emerging evidence suggests that metabolic pathways may critically modulate IFN-γ responses; however, the functional interplay between NAD/NAMPT metabolism and IFN-γ signaling in melanoma cells remains poorly defined. Methods We integrated transcriptomic, bioinformatic, biochemical, and functional approaches in human and murine melanoma cell lines, together with analyses of TCGA datasets and a tissue microarray (TMA) cohort. Mechanistic studies included pharmacological and genetic perturbation of Bromodomain and Extra-Terminal motif (BET) epigenetic factor BRD4, Interferon Regulatory Factor 1 (IRF1), and NAMPT, chromatin immunoprecipitation (ChIP) assays, and metabolic analyses. Tumor-T cell co-culture systems were used to assess the impact of melanoma-cell NAMPT modulation on T-cell behavior. Results IFN-γ induced NAMPT expression through a BRD4/IRF1-dependent transcriptional program. In turn, NAMPT activity was required to sustain IFN-γ signaling, as its inhibition impaired STAT1 activation and downstream transcriptional responses. Mechanistically, NAMPT-dependent NAD metabolism supported mitochondrial complex I activity and oxidative metabolism and was required for efficient BRD4 recruitment to IFN-responsive promoters, including CD274/PD-L1 and NAMPT itself. Across melanoma datasets and patient samples, NAMPT expression correlated with IFN-γ–responsive genes, including PD-L1. Functionally, modulation of NAMPT in melanoma cells influenced T-cell cytotoxicity and migration in co-culture systems. Conclusions Overall, these findings identify NAMPT as a key metabolic component of the IFN-γ response network in melanoma cells, establishing a feed-forward regulatory circuit linking cytokine signaling, chromatin regulation, and mitochondrial metabolism. This work provides a framework to investigate how metabolic control of IFN-γ signaling shapes tumor-immune interactions.
Abstract from DOAJ. Public domain (CC0 1.0).
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Fiorilla, I., Ghezzi, B., Ponzano, A., et al. (2026). Bi-directional regulation between NAD/NAMPT and IFN-γ/PD-L1 axes via BRD4/IRF1 and mitochondrial respiration in metastatic cutaneous melanoma. Journal of Experimental & Clinical Cancer Research. https://doi.org/10.1186/s13046-026-03734-2