Yifei Sanjie Formula in improving the response to PD-1 blockade by lung cancer through the attenuation of the USP7-NR1H4-bile acid metabolism axis.

Yifei Sanjie Formula (YFSJF), a traditional Chinese medicine (TCM) formulation, has been clinically observed to enhance the efficacy of programmed cell death protein 1 (PD-1) blockade in patients with advanced lung adenocarcinoma. However, the underlying mechanisms of its effect remain unclear. This study aimed to clarify the molecular mechanism by which YFSJF enhances the efficacy of PD-1 inhibitors, with a focus on its role in regulating the ubiquitin-specific protease 7 (USP7)-nuclear receptor subfamily 1 group H member 4 (NR1H4)-bile acid metabolism axis. Using in vitro and in vivo models, including Lewis lung carcinoma (LLC) cells and a male C57BL/6 mouse xenograft model, we evaluated the effects of YFSJF on tumor growth, migration, invasion, and the synergistic effect with PD-1 inhibitors. Metabolomic analysis, transcriptomic profiling, and molecular biology were employed to examine the role of the USP7-NR1H4-bile acid metabolism axis. YFSJF significantly inhibited the proliferation, migration, and invasion of lung cancer cells while enhancing the antitumor efficacy of PD-1 blockade by modulating immune responses. USP7 was found to be highly expressed in lung cancer tissues and was associated with poor prognosis. We further found that YFSJF promoted the ubiquitin-mediated degradation of NR1H4 by downregulating USP7, thereby altering the levels of bile acid metabolites such as taurochenodeoxycholic acid (TCDCA) and glycocholic acid (GCA). USP7 knockdown impaired NR1H4 stability via the ubiquitin-proteasome pathway, influencing bile acid metabolism and immune-related pathways. YFSJF regulates bile acid metabolism reprogramming through the USP7-NR1H4-bile acid metabolism axis to affect immune-related pathways and enhance the efficacy of PD-1 inhibitors. These findings provide insights into the mechanisms underlying the immunomodulatory role of YFSJF and support its use as a complement to immunotherapy in lung cancer treatment.