Objective：To explore the expression of microRNA-133b in colorectal carcinoma cells and its effect on migration and invasion of colorectal cancer cells.
Methods：The expression of microRNA-133b (miR-133b) in normal human colon cells and four colorectal cancer cell lines with different malignant potential were examined by real-time PCR. The miR-133b genomic sequences were amplified from human genomic DNA by PCR and constructed into the eukaryotic expression vector. SW-620 cells were transfected with the identified plasmid by Effectene. SW-620 cell lines with stable expression of miR-133b or control were obtained after a 3-week selection period in medium supplemented with G418, designated SW-620-133b and SW-620-HK, respectively. Cell migration and invasion was measured in vitro by wound healing assay and transwell assay.
Results：miR-133b expression was shown to be greatly downregulated in human colon cancer cells (SW-480，HT-29，LoVo，SW-620) compared to normal colon cells CCD-18Co (P＜0.05), and this downregulation was inversely associated with degree of malignancy of colorectal cancer cells. In cancer SW-620 cells, expression of miR-133b significantly inhibited tumor cell migration and invasion, with the inhibiting rates of (42.2±2.6) % and (66.3±8.7) %, respectively.
Conclusions：The expression of miR-133b is downregulated in human colorectal cancer cells. Overexpression of miR-133b significantly inhibits SW-620 cell migration and invasion.