Abstract 5286: The acquisition of CD11a via trogocytosis by gastric cancer cells after contact with T cells increases adhesion to endothelial cells

It has been revealed that plasma membrane and membrane molecules are frequently transferred upon cell-to-cell contact, which is named as trogocytosis, and that this phenomenon between immune cells plays an important role in the immune responses. However, the physiological roles of trogocytosis between cancer cells and immune cells are poorly understood. In this study, we hypothesized that the transfer of membrane molecules from immune cells to cancer cells arrows cancer cells to acquire the functions involved in extravasation, which results in increased metastatic ability. Gastric cancer cell line, OCUM-1 was co-cultured with T cells whose plasma membrane was stained with PKH26. Flowcytometric analysis revealed that OCUM-1 became positive for PKH26 at 3 hours and the positive rate increased over time. The acquisition of PKH26 was dependent on cell-to-cell contact and suggested to be attributed to trogocytosis. Among various immunological synapse molecules of T cells, OCUM-1 came to express CD45, CD3, CD4 and CD11a after 8 hours of coculture (positive rate, CD45: 64.0%, CD3: 36.0%, CD4: 11.3%, CD11a: 16.8%). We focused on CD11a, which belongs to β2 integrins and aids immune cells to adhere endothelial cells and extravasate. After co-culture OCUM-1 with T cells on which CD11a was fluorescently labelled with anti-CD11a antibody, CD11a was transferred from T cells to OCUM-1. The expression level of CD11a on OCUM-1 was accelerated after co-culture with activated T cells (positive rate, with T cells: 12.6% vs with activated T cells: 65.9%) and the adhesion rate on endothelial cells increased in a CD11a dependent manner (adhesion rate, monoculture: 2.0±0.64%, co-culture: 6.3±2.0%, co-culture (pre-treat with CD11a antibody): 2.3±1.4%, n=10, monoculture vs co-culture: p<0.0001, co-culture vs pre-treat: p<0.0001).These results suggest that after escape from attack of T cells, cancer cells could acquire CD11a from T cells and increase the adhesive property on endothelial cells of target organs, which might result in promotion of intravenous metastasis. Citation Format: Hideyo Miyato, Eri Suizu, Rei Takahashi, Misaki Matsumiya, Hirofumi Sonoda, Hideyuki Ozawa, Hironori Yamaguchi, Naohiro Sata, Joji Kitayama. The acquisition of CD11a via trogocytosis by gastric cancer cells after contact with T cells increases adhesion to endothelial cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5286.