Rab11 regulates E-cadherin expression and induces cell transformation in colorectal carcinoma.

Background: In the process of epithelial mesenchymal transition EMT, the disassembly of junctional adhesion complexes such as E-cadherin is a remarkable sign during changes in cell morphology and polarity. However, E-cadherin expression is dynamic, and is regulated by the cellular endocytic system; it is also involved in cell signaling mechanisms. In this study, we investigated the role of E-cadherin in colorectal tumors and the relationship with recycling endosome protein Rab11 in colon cell transformation.

Methods: For tissue screening, the expressions of E-cadherin and Rab11 in colorectal tumors were identified by immunohistochemistry in 113 patients with colorectal carcinoma. For the in vitro cell experiment, GFP-tagged Rab11 plasmid was transfected into HT29 colon cells, E-cadherin expression and cell transformation were monitored by Western blot and confocal microscopy.

Results: In immunohistochemistry, the mean score of E-cadherin in tumor and normal tissues was 1.41 ± 0.06 and 1.08 ± 0.06 (p < 0.05). The mean score of Rab11 in tumor and normal tissues was 0.51 ± 0.05 and 0.18 ± 0.02 (p < 0.05). Synchronous overexpression of E-cadherin and Rab11 was noted in 74 patients (66.5%) with colorectal carcinoma. When GFP-tagged Rab11 plasmid was overexpressed in cultured colon cell line HT-29, the E-cadherin expression was up-regulated, and cell membrane protrusion was induced, which resulted in cell transformation and cell migration.

Conclusions: This study demonstrated the importance of the overexpression of Rab11 and E-cadherin in colorectal cancer. The results indicated that Rab11 together with E-cadherin might be potential markers for colorectal cancer progression and treatment.