American Association for Cancer Research
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Figure S7 from FASN Inhibition Decreases MHC-I Degradation and Synergizes with PD-L1 Checkpoint Blockade in Hepatocellular Carcinoma

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journal contribution
posted on 2024-03-15, 07:21 authored by Jiao Huang, Wai Ying Tsang, Xiao-Na Fang, Yu Zhang, Jie Luo, Lan-Qi Gong, Bai-Feng Zhang, Ching Ngar Wong, Zhi-Hong Li, Bei-Lei Liu, Jin-Lin Huang, Yu-Ma Yang, Shan Liu, Liu-Xian Ban, Yiu Hong Chan, Xin-Yuan Guan

Figure S7


Hong Kong Research Grant Council

National Natural Science Foundation of China

Shenzhen Key Laboratory for Cancer Metastasis and Personalized Therapy

Shenzhen Fundamental Research Program (深圳基础研究计划项目)

Shenzhen Science and Technology program

Basic and Applied Basic Research Foundation of Guangdong Province



Immune checkpoint inhibitors (ICI) transformed the treatment landscape of hepatocellular carcinoma (HCC). Unfortunately, patients with attenuated MHC-I expression remain refractory to ICIs, and druggable targets for upregulating MHC-I are limited. Here, we found that genetic or pharmacologic inhibition of fatty acid synthase (FASN) increased MHC-I levels in HCC cells, promoting antigen presentation and stimulating antigen-specific CD8+ T-cell cytotoxicity. Mechanistically, FASN inhibition reduced palmitoylation of MHC-I that led to its lysosomal degradation. The palmitoyltransferase DHHC3 directly bound MHC-I and negatively regulated MHC-I protein levels. In an orthotopic HCC mouse model, Fasn deficiency enhanced MHC-I levels and promoted cancer cell killing by tumor-infiltrating CD8+ T cells. Moreover, the combination of two different FASN inhibitors, orlistat and TVB-2640, with anti–PD-L1 antibody robustly suppressed tumor growth in vivo. Multiplex IHC of human HCC samples and bioinformatic analysis of The Cancer Genome Atlas data further illustrated that lower expression of FASN was correlated with a higher percentage of cytotoxic CD8+ T cells. The identification of FASN as a negative regulator of MHC-I provides the rationale for combining FASN inhibitors and immunotherapy for treating HCC. Inhibition of FASN increases MHC-I protein levels by suppressing its palmitoylation and lysosomal degradation, which stimulates immune activity against hepatocellular carcinoma and enhances the efficacy of immune checkpoint inhibition.

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