Abstract 2684: Clinical significance of GDP-mannose-4,6-dehydratase mutation and loss of fucosylation in colorectal cancer

(Background and Aim) Oligosaccharides are one of the most important factors in the posttranslational modification of proteins and lipids. Glycomics, the systematic study of glycans and glycan-binding proteins in various biological systems, is an emerging field in the post-genomics and post-proteomics era. In particular, fucosylation is one of the most important glycosylation involved in cancer and inflammation. Fucosylation, which comprises the transfer of a fucose residue to oligosaccharides and proteins, is regulated by many kinds of molecules, including several kinds of fucosyltranferases, GDP-fucose synthetic enzymes, and GDP-fucose transporter(s). Fucosylation is increased during carcinogenesis of many cancers through the up-regulation of expression of fucosylation-regulatory genes as described above. In contrast, we found a colon cancer cell line HCT116, which had complete loss of fucosylation due to the mutation of a GDP-fucose synthetic enzyme, GMDS (GDP-mannose-4, 6-dehydratase) a few years ago. While knockout mice of a GDP-fucose synthetic enzyme are lethal (Smith et al J Cell Biol, 158, 2002), HCT116 cells showed more aggressive pheno-type, including in vivo tumor growth and metastasis. The underlying mechanisms were found to be an escape from TRAIL-mediated immuno-surveillance of NK cells (Moriwaki et al, Gastroenterology 137, 2009). In the present study, we investigated whether or not the GMDS mutation was really found in clinical samples of colorectal cancer. (Subjects and Methods) Thirteen cases of liver metastasis, 6 cases of lymph node metastasis and 81 cases of the original cancer tissues derived from patients with colorectal cancer were included in this study. All projects were approved by the ethical committee of Osaka University. GMDS mutation was analyzed by RT-PCR using primers, which include all exons of GMDS gene. Immunohistochemical experiments were performed using AAL lectin, which recognizes all types of fucosylation. (Results and Discussion) Approximately 10-15% of GMDS mutation was found in the original cancer tissue as well as their metastatic liver cancer and lymph node metastasis. However no mutation was found in normal colon tissue around cancer. Most GMDS mutation was a hetero-type, but not a homo-type, which was found in HCT 116 cells. Immunohistochemical analysis showed complete loss of fucosylation in a few cases of metastatic cancer. These data indicate the involvement of GMDS mutation in the progression of colorectal cancer. Citation Format: Kotarosumitomo Nakayama, Kenta Moriwaki, Mayuka Shimomura, Hironobu Fujii, Shinji Takamatsu, Yoshihiro Kamada, Kohei Murata, Eiji Miyoshi. Clinical significance of GDP-mannose-4,6-dehydratase mutation and loss of fucosylation in colorectal cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2684. doi:10.1158/1538-7445.AM2013-2684