miRNA-mediated expression switch of cell adhesion genes driven by microcirculation in chip

Changes in cell adhesion molecule (CAM) expression and miRNAs regulating them are known to be involved in malignant progression in colon cancer. We investigated expression profiles of CAM genes and non-coding RNAs in CaCo2 colon cancer cells in static culture and under dynamic flow conditions perfused in microfluidic chip emulating physiological microenvironment. We incubated monolayers of CaCo2 cells in Transwell® units either under static conditions or under flow in a microfluidic chip. We identified 7 up-regulated CAM genes (CD44, CDH7, CEACAM5, CEACAM6, CYR61, L1CAM and VCAN), 7 down-regulated genes (COL12A1, FGA, FGB, FGG, GJA1, ITGA5 and LAMA1) and 69 miRNAs targeting them under the influence of microcirculation. The revealed network comprised CAM genes known to interact with each other and 13 miRNAs simultaneously regulating more than one of them. Undifferentiated Caco2 cells were seeded on individual polyether membrane inserts with 0.143 cm2 surface area and 1.0 μm pore diameter, cut out from HTS Transwell®-96 well permeable support (Corning Inc., USA), with cell density approximately 60,000 cells/well. The cells were incubated under conditions for differentiation for 7 days in MEM with 10% FBS, 0.1 mM non-essential aminoacids, 0.1% penicillin-streptomycin in 5% CO2, 37° C, changed three times. Transwell® inserts with CaCo2 monolayers were either kept on the microplate or put into microfluidic chip. The culture medium microcirculation parameters were ±20 kPa and 2 Hz resulting in the pulsatile (0 - 0.85 µl/s) medium flow with mean flow rate of 4.13 μl/min. After 24-h incubation the cells were lysed in 700 μl of Qiazol lysis reagent (Qiagen, Germany) and subjected to microarray expression analysis. The experiments were performed in triplicates.