Fasn, short for fatty acid synthase, is a key enzyme in lipid metabolism, catalyzing long-chain fatty acid synthesis. It plays a crucial role in de novo fatty acid synthesis, which is important for various biological processes, including cell membrane formation, energy storage, and signal transduction [4].

In multiple cancer types, Fasn has been shown to be a significant contributor. In colorectal cancer, mutations in FBXW7β, an E3 ligase of Fasn, lead to sustained lipogenesis as it can no longer degrade Fasn, promoting cancer growth [1]. In cervical cancer, Fasn promotes lymph node metastasis via cholesterol reprogramming and lymphangiogenesis, and its knockdown or inhibition can reduce metastasis in vivo [2]. In hepatocellular carcinoma, Fasn inhibition increases MHC-I levels, promoting antigen presentation and synergizing with PD-L1 checkpoint blockade to suppress tumor growth [3]. In Clonorchis sinensis infection-related intrahepatic cholangiocarcinoma, Fasn-mediated fatty acid biosynthesis remodels the immune environment, leading to an immunosuppressive state and tumor progression, and Fasn inhibitor treatment can reverse this [4]. In diffuse large B-cell lymphoma, ZDHHC21, a palmitoyltransferase, negatively regulates Fasn by mediating its palmitoylation, and targeting the ZDHHC21/Fasn axis may be a therapeutic strategy [5]. In colorectal cancer, FABP5 interacts with Fasn, activates the ubiquitin-proteasome pathway to decrease Fasn expression, suppressing mTOR signaling and facilitating autophagy, and the Fasn inhibitor orlistat has anti-cancer effects [6]. In intrahepatic cholangiocarcinoma, circRNA MBOAT2 promotes cancer progression by facilitating Fasn mRNA cytoplasmic export, regulating lipid metabolism [7].

In conclusion, Fasn is essential for lipid metabolism. Gene-knockout or conditional-knockout mouse models and other loss-of-function experiments have revealed its significant role in cancer development, metastasis, and immune-related processes. Understanding Fasn's function in these disease areas provides potential therapeutic targets for cancer treatment.