Acute IFN-γ elicits long-term proteomic IFN-γ signature in melanoma cells

Interferon-{gamma} (IFN-{gamma}) is a central mediator of antitumor immunity, and its downstream effects are widely assumed to require continuous cytokine exposure. Here, we applied state-of-the-art mass spectrometry (MS)-based proteomics to patient-derived melanoma cells exposed either continuously to IFN-{gamma} or to a 3-hour pulse followed by cytokine removal. A transient IFN-{gamma} exposure was sufficient to establish a stable proteomic state indistinguishable from continuous stimulation, demonstrating that IFN-{gamma}-induced remodeling is rapidly triggered and durably maintained independently of ligand persistence. Proximal JAK-STAT signaling was rapid, saturable at low cytokine concentrations, and fully reversible upon washout, yet downstream proteomic programs remained durably imprinted. In contrast, functional consequences such as cytostasis remained dose-dependent, revealing a disconnect between signaling activation and phenotypic sensitivity. Together, these findings challenge long-standing assumptions about IFN-{gamma} signaling, redefine the temporal requirements for cytokine-driven tumor cell programming, and provide a mechanistic framework for improving immunotherapies primarily working via IFN-{gamma}-signaling and physiologically relevant in vitro models of tumor-immune interactions.