Objective: To show that Stat3 plays a key role in the G1 to S phase transition in colon cancer cells.
Methods: Human colon cancer cell lines SW480 and HCT116 were transfected with Stat3 antisense oligonucleotide mediated by liposome, MTT assay was used to measure the proliferation, flow cytometry was applied to analyze the cell cycle, and the expressions of Stat3, phosphorylation-specific Stat3 (tyrosine 705), Cyclin D1, Cyclin E, CDK2, CDK4, CDK6, p21 and p27 were measured by western blot.
Results: SW480 and HCT116 colon cancer cell lines expressed constitutively activated Stat3. Targeting of Stat3 using antisense oligonucleotide which directed against the translation site resulted in growth inhibition, downregulation of Stat3, p-Stat3, Cyclins and CDKs, and up-regulation of p21 and p27.
Conclusion: Our findings suggest that Stat3 plays an important role in the G1 to S phase transition in colon cancer cells, Stat3 orchestrates cell cycle by regulating the balance between CDK/Cyclin complex and CKI.