Objective        To study the effect of pyruvate dehydrogenase kinase isozyme 1(PDK-1) on 5-fluorouracil (5-FU)-induced apoptosis of colon cancer cells.       Methods        Three interference sequences (interference group) and a negative control sequence of PDK-1 shRNA (control group) were designed to construct pGenesil-1 recombinant plasmid expression vector and pGenesil.1 negative control (pGenesil.1-NC) plasmid vector

respectively. The plasmid was transfected into LS174T cells using liposome and drugs were screened with G418. Effect of RNA interference on 5-FU-induced apoptosis of colon cancer cells was detected by real-time PCR and Western blotting

respectively. Effect of 5-FU on growth and apoptosis of colon cancer cells was detected by MTT assay and flow cytometry

respectively.       Results         Real-time PCR and Western blotting showed that the 3 interference sequences of PDK-1 shRNA inhibited the expression of PDK-1 in LS174T cells

with a maximum inhibitory rate of over 70%. MTT assay demonstrated that the growth inhibiting rate of LS174T cells interfered with PDK-1 was significantly higher in interference group than in control group 48 h after 5-FU was used (P0.05). Flow cytometry displayed that the apoptosis rate of colon cancer cells was significantly higher in interference group than in control group (P0.05).       Conclusion         PDK-1 shRNA can down-regulate the expression of PDK-1 in LS174T cells and  PDK-1 interference in combination with 5-FU can promote the apoptosis of colon cancer cells.