Objective      To study the effect and mechanism of human interleukin 12 (IL-12) on biological property of colon cancer stem cells (CSCs).       Methods      Colon CSCs were transfected with IL-12/lentivirus recombinant plasmids to construct the cell model over-expressing IL-12. NOD/SCID mice were inoculated with the transfected colon CSCs. The growth of tumors initiated by CSCs in mice was observed

and the invasiveness of colon CSCs was detected by Transwell. Cell apoptosis was detected b

y flow cytometry

the expression of CK20 was detected by immunohistochemistry

and the protein expression of STAT6

p-STAT6

survivin

IL-12 and IL-4 was detected by Western blotting.       Results      After IL-12 transfection

the capacity of invasiveness of colon CSCs decreased by 40%

the tumorsphere formation capacity reduced

and cell apoptosis increased [(45.2±5.6)% vs. (4.1±1.2)%

]

. After injection into NOD/SCID mice

tumors initiated by colon CSCs transfected with lentivirus/IL-12 showed markedly reduced capacity of tumor growth

and the rate of tumor inhibition was 64.03%. The mean volume of tumor initiated by colon CSCs transfected with lentivirus/IL-12 was 189±21 mm

3

and the mean weight was 1 958.2±41.2 mg. However

the mean volume of tumor initiated by colon cancer stem cells transfected with lentivirus was 1 785±32 mm

3

and the mean weight was 5 369.8±41.3 mg. Western blotting revealed that over-expression of IL-12 reduced the expression of IL-4 and p-STAT6 in colon CSCs supernatants.       Conclusion      IL-12 can reduce the self-renewal and invasiveness of colon CSCs

and promote colon CSCs differentiation and apoptosis through IL-4/STAT6 pathway.