OBJECTIVETo detect the expression of PSF1 (partner of Sld five 1) in colon cancer specimens, and to explore the effect of RNA interference targeting PSF1 on the proliferation of colon cancer cells and its mechanism.

METHODSExpression level of PSF1 protein in colon cancer specimens was detected by Western blot in 40 patients with colon cancer from May 2004 to December 2006. The short hairpin RNA (shRNA) plasmid targeting PSF1 was transfected into LOVO, HT-29 and HCT116 cells with liposome, then the expression level of PSF1 protein was measured by Western blot, the effect of PSF1 shRNA plasmid transfection on cell proliferation by MTT assay, anchorage-independent growth by soft agar colomy-formation assay, and PSF2, PSF3 and SLD5 mRNA expression by quantitative reverse transcription polymerase chain reaction.

RESULTSThe relative expression level of PSF1 protein in colon cancer tissues was 0.485±0.113, which was significantly higher than that in adjacent normal mucosa tissues (0.056±0.014, P<0.01). Western blot showed that the expression level of PSF1 protein was significantly decreased in colon cancer cells transfected with PSF1 shRNA plasmid. After PSF1 shRNA plasmid transfection, cell proliferation was significantly suppressed, the soft agar colony-forming rates of LOVO, HT-29 and HCT116 cells were significantly lower than those in control groups (P<0.05), meanwhile the expression levels of PSF2, PSF3 and SLD5 mRNA were significantly decreased (P<0.05).

CONCLUSIONSPSF1 is significantly up-regulated in colon cancer tissues compared with adjacent normal mucosa tissues. ShRNA plasmid targeting PSF1 can inhibit the expression of PSF1 gene, suppress the proliferation of colon cancer cells, suggesting that it may be a new therapeutic target for colon cancer.