AIM: To observe the gene silencing mediated by the specific shRNA targeted against β-catenin and its effect on cell proliferation and cycle distribution in the human colon cancer cell line Colo205.

METHODS: Two shRNA plasmid vectors against β-catenin were constructed and transfected into Colo205 cells with Lipofectamine TM 2000. The down-regulations of β-catenin, c-myc and cyclinD1 expressions were detected by RT-PCR and western blot analysis. The cell proliferation inhibitions were determined by MTT assay and soft agar colony formation assay. The effect of these two β-catenin shRNAs on cell cycle distribution and apoptosis was examined by flow cytometry.

RESULTS: These two shRNA vectors targeted against β-catenin efficiently suppressed the expression of β-catenin and its down stream genes, c-myc and cyclinD1. The expression inhibition rates were around 40%-50% either at the mRNA or at the protein level. The shRNA-mediated gene silencing of β-catenin resulted in significant inhibition of cell growth both on the culture plates and in the soft agar. Moreover, the cancer cells showed significant G 0/G 1 arrest and increased apoptosis at 72 h post transfection due to gene silencing.

CONCLUSION: These specific shRNAs targeted against β-catenin could have a gene silencing effect and block the WNT signaling pathway. They could inhibit cell growth, increase apoptosis, and induce cell cycle arrest in Colo205 cells. ShRNA interference against β-catenin is of potential value in gene therapy of colon cancer.