Background/Aim: A protein-bound polysaccharide, polysaccharide K (PSK), is a non-specific immunological agent used in the treatment of colon cancer, however few studies have investigated the genetic changes in cancer cells treated with PSK. Therefore, we investigated the effect of PSK on cancer cell invasion, which is an indicator for the malignancy of colon cancer cell lines, and performed additional genetic analyses.

We performed Matrigel invasion assay to examine whether the invasive ability of colon cancer cell lines HT29, HCT116, and LoVo would be impacted upon stimulation with PSK. We used reverse transcription-polymerase chain reaction (RT-PCR) to evaluate for changes in the expression of matrix metalloproteinases (MMP)-2 and - 9 upon stimulation of colon cancer cell lines with PSK.

The mean number of invasive cells in untreated HCT116, HT29, and LoVo cells was 146, 81, and 65, respectively, while that in PSK-treated cell lines was reduced to 24, 7, and 4, respectively. mRNA levels of MMP2 and MMP9 in PSK-stimulated cell lines were significantly lower than those in unstimulated cell lines.

PSK reduced the expression of MMP2 and MMP9 mRNAs and cell invasion of this panel of colon cancer cell lines.