Abstract:

Objective To discuss the effect of Cadherin-17 on the proliferation and apoptosis of the colorectal cancer （CRC） cells，and to clarify its possible mechanism. Methods The Cadherin-17 gene over-expression and small interference plasmids were constructed and packaged as the lentivirus and transfected into the SW480 cells to construct the stable transfection strain of over-expression and interference virus. The expression levels of Cadherin-17 mRNA and protein in the cells were detected by real-time fluorescence quantitative PCR （RT-qPCR） and Western blotting methods， and the transfection efficiency was verified and the stable transfection strain was identified. The SW480 cells were divided into control group， empty vector group， Cadherin-17 over-expression plasmid （OV-Cadherin-17） group and Cadherin-17 small interference plasmid （si-Cadherin-17） group. The activities of cells in various groups were detected by CCK-8 assay；the apoptotic rates of cells in various groups were detected by flow cytometry； the expression levels of Cadherin-17，B-cell lymphoma-2 （Bcl-2）， Bcl2-associated X （Bax）， cytochrome c （Cyt-c） and cysteinyl aspartate specific proteinase-3 （Caspase-3），and the phosphatidylinosital-3-kinase/protein kinase B/mamalian target of repamycin （PI3K/AKT/mTOR） signaling pathway-related proteins in the cells in various groups were detected by Western blotting methods. The cells were treated with PI3K inhibitor LY294002 and divided into control group， LY294002 group， OV-Cadherin-17+LY294002 group，and si-Cadherin-17+LY294002 group； the proliferation activities and apoptotic rates of cells in various groups and the expression levels of Bcl-2，Bax，Cyt-c，Caspase-3 and the expression levels of PI3K/AKT/mTOR signaling pathway-related proteins in the cells in various groups were detected. Results The RT-qPCR and Western blotting results showed that the OV-Cadherin-17 and si-Cadherin-17 transfection and stable transfection stain were successfully constructed.Compared with control group， the proliferation ability of the cells in OV-Cadherin-17 group was increased （P<0.01）， the apoptotic rate was decreased （P<0.01）， the expression levels of Bax and Caspase-3 proteins in the cells were decreased （P<0.01）， the expression levels of Bcl-2 and Cyt-c proteins in the cells were increased （P<0.01）， and the expression levels of phosphorylated PI3K（p-PI3K），phosphorylated AKT（p-Akt）， and phosphorylated mTOR（p-mTOR） proteins were increased （P<0.01）； the proliferation abilities of the cells in si-Cadherin-17 and LY294002 groups were decreased （P<0.01）， the apoptotic rates were increased （P<0.01）， the expression levels of Bax and Caspase-3 proteins in the cells were increased （P<0.01）， the expression levels of Bcl-2 and Cyt-c proteins in the cells were decreased （P<0.01），and the expression levels of p-PI3K， p-AKT， and p-mTOR proteins in the cells were decreased （P<0.01）； compared with LY294002 group， the proliferation ability of the cells in OV-Cadherin-17+LY294002 group was increased （P<0.01）， the apoptotic rate was decreased （P<0.01）， the expression levels of Bax and Caspase-3 proteins in the cells were decreased （P<0.01）， the expression levels of Bcl-2 and Cyt-c proteins in the cells were increased （P<0.01）， the expression levels of p-PI3K， p-AKT， and p-mTOR proteins were increased （P<0.01）， the proliferation activity of the cells in si-Cadherin-17+LY294002 group was decreased （P<0.01）， the apoptotic rate was increased （P<0.01）， the expression levels of Bax and Caspase-3 proteins in the cells were increased （P<0.01）， the expression levels of Bcl-2 and Cyt-c proteins in the cells were decreased （P<0.01），and the expression levels of p-PI3K， p-AKT， and p-mTOR proteins were decreased （P<0.01）. Conclusion Cadherin-17 can promote the proliferation and inhibit the apoptosis of the CRC cells， and its mechanism may be related to the activition of PI3K/AKT/mTOR signaling pathway regulated by Cadherin-17.

Key words: Cadherin-17, Colorectal neoplasm, Phosphatidylinosital-3-kinase/protein kinase B/mamalian target of repamycin signaling pathway, Cell proliferation, Apoptosis