Abstract Lung cancer is the leading cause of cancer-associated deaths worldwide. Metabolic reprogramming facilitates the growth advantage of cancer cells and is a hallmark of cancer. Although multiple studies have investigated the cancer-specific metabolic status of lung cancer, it remains unclear. Aberrant fucosylation, which results from the deficiency or overexpression of fucosyltransferases, is also associated with a variety of cancers, including lung cancer. However, the role and regulatory mechanism(s) of fucosylation in lung cancer remain largely unknown. In order to elucidate the specific metabolic status of human lung cancer tissues, we performed metabolomics profiling of paired tumor and normal tissues from patients with non-small cell lung cancer (NSCLC) using both capillary electrophoresis mass-spectrometry (CE-MS) and imaging mass-spectrometry (I-MS). We used principle component analysis (PCA) to confirm that human lung cancer has distinctive metabolic patterns. We revealed upregulation of the GDP-L-fucose de novo pathway, which regulates the level of fucosylated glycoproteins, in lung cancer tissues compared to the adjacent non-malignant lung tissues. In order to elucidate the mechanisms by which fucosylation is increased in lung cancer tissues, gene expression of fucosyltransferases (FUT1-9) were evaluated. We confirmed that fucosyltransferase 3 (FUT3) expression was increased in a significant proportion of human primary lung adenocarcinoma samples and was correlated with sLeX expression. A fucosylation inhibitor, 6-alkynyl-fucose, inhibited the proliferation and invasion of lung cancer cell lines with high endogenous FUT3 expression in vitro. Exogenous FUT3-overexpressing lung cancer cells did not show increased proliferation, but showed significantly increased invasion and adhesion activities in vitro. In order to confirm whether FUT3 promoted metastasis of A549 cells in an experimental lung metastatic mouse model, A549 lung cancer cells expressing EGFP (A549-EGFP) and A549 lung cancer cells overexpressing FUT3 (A549-FUT3) were intravenously administered to BALB/C nude mice and the numbers of metastatic nodules in the lungs were counted after 8 weeks. In concordance with our observations in vitro, there was no significant difference in tumor growth between the A549-EGFP and A549-FUT3 treatments in vivo. Interestingly, injection of A549-FUT3 resulted in an increase in the number of lung metastases compared to the injection of A549-EGFP, suggesting that FUT3 is a positive regulator of cancer invasion and metastasis. Furthermore, high expression of FUT3 in lung cancer tissues predicted a poorer prognosis for patients with lung adenocarcinoma. These findings highlight the important roles of protein fucosylation in lung cancer progression and provide the preclinical rationale to target this pathway in lung cancer treatment. Citation Format: Keita Masuzawa, Hiroyuki Yasuda, Atsushi Matsuda, Hideki Terai, Yuki Sugiura, Junko Hamamoto, Daisuke Arai, Shizuko Kagawa, Katsura Emoto, Shinnosuke Ikemura, Ichiro Kawada, Kenzo Soejima, Koichi Fukunaga. The role of protein fucosylation in lung cancer progression [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 365.