Objective: To explore the effects of human FRNK gene on E-cadherin/beta-catenin complex in colon cancer cell line Colo320WT cells stimulated with extrinsic gastrinl7.
Methods: AdEasy system was used to construct pAdhFRNK expressing human FRNK gene by recombination in E. coli. BJ5283. pCR3.1/GR plasmid expressing gastrin receptor CCK-2 was transfected into colon cancer cell line Colo320 cells by Lipofectamine 2000 and expressing stably CCK-2R clones were screened by G418 (500 pg/ml). The expression levels of gastrin receptor in Colo320 cells and the transfected Colo320WT cells were assayed by RT-PCR. Colo320WT cells were treated by 10(-8) mol/L gastrinl7 for 12 h; and after Colo320WT cells were infected by pAdhFRNK (MOI: 100) for 2 d the cells were treated by gastrin17 for 12 h again. The expression levels of E-cadherin and beta-catenin in TX-100 soluble fraction and TX-100 insoluble fraction of Colo320WT cells were assayed by co-immunoprecipation and Western blot. E-cadherin and beta-catenin's distribution in Colo320WT cells were detected by immunocytochemistry.
Results: When 10(-8) mol/L gastrin17 stimulated Colo320WT cells for 12 h, the expression levels of E-cadherin and beta-catenin in TX-100-soluble fraction decreased apparently, while the expression levels of E-cadherin and beta-catenin in TX-100-insoluble fraction increased markedly. When pAdhFRNK infected Colo320WT cells for 2 d and 10(-8) mol/L gastrin17 treated the cells for 12 h, the expression levels of E-cadherin and beta-catenin in TX-100-soluble fraction increased apparently again, and the expression levels of E-cadherin and beta-catenin in TX-100-insolutble fraction decreased markedly. Immunocytochemistry showed that the distribution of E-cadherin and beta-catenin was translocated from plasma membrane into cytoplasm and nucleus in the cells stimulated with gastrinl7, and after the cells were infected with pAdhFRNK and stimulated by gastrinl7 again. beta-catenin was mainly observed in cytoplasm and little nuclear immunoreactivity.
Conclusion: An adenovirus vector pAdhFRNK can inhibit abnormal distribution of E-cadherin and beta-catenin in the gastrin17-stimulated cells. The mechanism is probably that hFRNK can disphosphorylate phosphorylated FAK and block FAK pathway.