KRAS-USP15 axis promotes TGF-β/SMAD signaling and glycolytic flux to accelerate NSCLC pathogenesis.

[BACKGROUND] Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer-related mortality worldwide, with activating KRAS mutations representing a key oncogenic driver. These mutations profoundly reprogram cellular metabolism, especially glycolysis, thereby sustaining uncontrolled tumor proliferation. We identified ubiquitin-specific peptidase 15 (USP15) as a pivotal regulator in KRAS-driven metabolic remodeling and tumor progression. This study aims to elucidate the biological functions and molecular mechanisms of USP15 in KRAS-mutant NSCLC.

[METHODS] Comprehensive bioinformatics analyses were performed to identify key metabolic genes significantly associated with NSCLC prognosis. The expression of USP15 was examined in KRAS-mutant NSCLC tissues and cell lines. Functional assays, including CCK-8, EdU incorporation, wound-healing, and subcutaneous xenograft tumor models, were employed to evaluate the oncogenic role of USP15 in vitro and in vivo. In addition, qPCR, Western blotting, ELISA, immunofluorescence, and Seahorse metabolic flux assays were integrated with transcriptomic and metabolomic profiling to comprehensively delineate the mechanisms by which USP15 regulates tumor metabolism and growth in KRAS-mutant NSCLC.

[RESULTS] USP15 expression was elevated in KRAS-mutant NSCLC and was transcriptionally regulated by the MEK/ERK signaling pathway. Silencing USP15 significantly inhibited NSCLC cell proliferation, migration, and tumorigenicity, while inducing apoptosis and enhancing chemosensitivity. Multi-omics analyses revealed that USP15 exerts its oncogenic function primarily through modulation of the TGF-β/SMAD signaling axis. Mechanistically, USP15 stabilized SMAD4 by deubiquitination and promoted the phosphorylation of SMAD2/3, thereby sustaining TGF-β/SMAD pathway activation. Moreover, USP15 enhanced glycolytic flux, evidenced by increased extracellular acidification rates and upregulated glycolytic genes expression, ultimately facilitating metabolic adaptation and tumor progression in KRAS-mutant NSCLC.

[CONCLUSION] USP15 acts as a critical mediator of oncogenic KRAS-driven metabolic reprogramming in NSCLC by promoting glycolysis via the TGF-β/SMAD signaling cascade. These findings uncover a previously unrecognized role of USP15 in linking metabolic regulation to tumorigenic signaling in KRAS-mutant NSCLC and suggest that targeting USP15 may represent a promising therapeutic strategy for this aggressive cancer subtype.