Abstract 4389: The role of Rab5 in epithelial growth factor stimulated E-cadherin internalization in spheroid growth of colon cancer cells

Abstract

Abstract In epithelial based cancer formation, such as colon cancer, the tumor growth is accompanied with malfunction of cell-cell contact inhibition which is regulated by E-cadherin. However, the dynamics of E-cadherin is complicated, the underlying mechanism in tumor nest growth and collective cell migration is still not clear. Rab5 is the endocytic vesicle protein for the membrane receptor internalization into early endosome. Therefore, this study is to investigate the role of Rab5 in E-cadherin turnover of spheroid formation in colon cancer cells. HT-29 colon cancer cells were used in this study. The cells with less anchorage ability were isolated for spheroid formation. The distribution of Rab5, E-cadherin and focal adhesion kinase were observed by immuno-confocal microscopy. The molecular expressions were analyzed by western blot. HT-29 cells showed well defined epithelial phenotype. In the result of immunostaining, Rab5 was distributed in the cytosol and the cell-cell contacts where it colocalized with E-cadherin. Rab5 was also observed in the cell leading edge, however, not much associated with focal adhesions. When HT-29 cell clusters were stimulated with epidermal growth factor, Rab5 was found abundant in the cell-cell contacts. In cell spheroid that derived from HT-29 cells, Rab5 and E-cadherin co-localization at cell-cell contacts was also increased. Furthermore, when cells were treated with Nocodazole, the tubulin inhibitor blocking tubulin-mediated endocytosis, Rab5 accumulated and colocalized with E-cadherin in the cell leading edge. The results of this study demonstrated Rab5 plays the novel role in E-cadherin turnover upon epidermal growth factor stimulation in the progress of spheroid formation and Rab5 may mediate E-cadherin endocytosis through the cell leading edge. Citation Format: Yu-Chun Wang, Yu-Chien Ching, Hui-Chun Chen, Chun-Pu Cheng, Chia-En Ku, Shin-Ru Lee, Wei-Ting Chao. The role of Rab5 in epithelial growth factor stimulated E-cadherin internalization in spheroid growth of colon cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4389.