Objective To determine the expressions of miR-138 and PDK1 in human colon cancer cells SW620 and identify the role of miR-138 in the invasion of SW620 cells by regulating the expression of PDK1.

Methods SW620 cells were cultured in vitro, and cellular morphology was observed by phase contrast microscope. The miR-138 which may regulate the expression of PDK1 was predicted by bioinformatics and identified using dual luciferase report system. The expressions of miR-138 and PDK1 were determined using qRT-PCR and Western blot after the transfection of miR-138 mimics by Lipofectamine 2000. The invasion of SW620 cells was detected in vitro by Transwell chamber.

Results SW620 cells showed short spindle shaped with uniform distribution by a phase contrast microscope. The expression of PDK1 detected by immunofluorescence was positive. miRanda and TargetScan showed miR-138 was well complementary with PDK1 gene. Using dual luciferase reporter system, miR-138 was proved to inhibit PDK1 expression by binding to 3′UTR of PDK1 mRNA. Results of qRT-PCR and Western blot showed that the over-expression of miR-138 down-regulated the expression of PDK1. The invasion of SW620 cells was suppressed by the over-expression of miR-138.

Conclusion miR-138 may negatively regulate the expression of PDK1 by binding to 3′UTR of PDK1 mRNA and inhibit the invasion of human colon cancer cells SW620.