Effects of αvβ6 integrin-mediated cell adhesion on 5-fluorouracil induced apoptosis in human colon carcinoma cell lines

AIM: To investigate the effects of αvβ6 integrin-mediated cell adhesion on 5-fluorouracil (5-FU) induced apoptosis in colon carcinoma cell lines.METHODS: The expression of the αvβ6 integrin in colon carcinoma cell lines HT-29 and WiDr cells was analyzed by flow cytometry. The apoptosis induced by 5-FU and the effects of αvβ6 integrin-mediated cell adhesion on 5-FU induced cell apoptosis were measured by enzyme-linked immunosorbent assay (ELISA) method and acridine orange-ethidium bromide (AO-EB) double fluorescent dye staining.RESULTS: Both the colon carcinoma cell lines HT-29 and WiDr cells expressed the αvβ6 integrin. The percentages of HT-29 and WiDr cells expression were 80.82% and 82.96%. 5-FU induced the apoptosis of colon carcinoma cell lines HT-29 and WiDr. The result of ELISA method displayed that enrichment factor (EF) of HT-29 and WiDr cells planted on fibronectin (FN)-ligand of αvβ6 integrin was lower significantly than the EF of HT-29 and WiDr cells planted on non-integrin ligand polylisin (1.11±0.04 vs 3.68±0.03, 1.09±0.02 vs 3.72±0.02, P<0.01) after cultured in medium containing 20 mg/L 5-FU for 48 h. When HT-29 and WiDr cells preincubated with αvβ6 integrin blocking antibody were planted on FN again, the EF of HT-29 and WiDr cells was higher significantly than those directly planted on FN without being blocked by αvβ6 integrin antibody (2.12±0.04 vs 1.11±0.04, 2.14±0.03 vs 1.09±0.02, P<0.01). The AO-EB double fluorescent dye staining displayed that the apoptosis percents of HT-29 and WiDr cells planting on FN were (5.6±1.1)% and (5.3±0.7)%, which were lower significantly than those planting on polylisin (37.0±1.4)%, (38.5±0.9)%, P<0.01. When HT-29 and WiDr cells preincubated with αvβ6 integrin blocking antibody were planted on FN again the percents of HT-29 and WiDr cells apoptosis were (19.5±1.2)% and (20.0±0.7)%, which increased significantly compared with those directly planting on FN without being blocked by αvβ6 integrin antibody (P<0.01). CONCLUSION: Colon carcinoma cell lines HT-29 and WiDr cells expressed αvβ6 integrin. The cell adhesion with FN mediated by αvβ6 integrin inhibits 5-FU-induced colon carcinoma cell apoptosis. The results suggest that cell adhesion may enhance drug resistance in colon carcinoma cell lines through inhibiting the cell apoptosis.