Aquaporin-1 activity of plasma membrane affects HT20 colon cancer cell migration

Recent studies revealed an important role of aquaporins (AQPs) in cell migration and migration-associated cell function such as angiogenesis, wound healing, and neutrophil motility. Migration of tumor cells is a crucial step in tumor invasion and metastasis. In the present study, we investigated the expression of AQP1 in human HT20 colon cancer cells and characterized its function in cell migration. By reverse transcription-polymerase chain reaction (RT-PCR) and immunoblot analysis, expression of AQP1 was identified in HT20 cell lines. Immunofluorescence analysis indicated expression of AQP1 protein in the plasma membrane of HT20 cells. The recombinant adenovirus expressing human AQP1 increased the mRNA and protein expression of AQP1 in HT20 cells. In contrary, the RNA interference vector of AQP1 effectively inhibited the mRNA and protein expression of AQP1 in HT20 cells. Adenovirus-mediated high expression of AQP1 in HT20 cells increased relative plasma membrane water permeability and migration rate in both wound healing and invasive transwell migration assays. In contrary, RNA interference vector-mediated low expression of AQP1 in HT20 cells reduced relative plasma membrane water permeability and migration rate. AQP1 expression induced relocalization of actin protein and activation of RhoA and Rac. In nude mice, AQP1 increased extravasation of HT20 Cells in lung after tail vein injection. The results provided the direct evidence that aquaporin-mediated plasma membrane water permeability plays an important role in colon cancer cell migration and may be associated with colon cancer invasion and metastasis.