Insulin-enhanced liposome-mediated gene transfer into a gastric carcinoma cell line.

1. Liposome-mediated transfection is useful due to no DNA constraints, lower immunogenicity and easy preparation. However, it has the disadvantage of low transfection efficiency. We aimed to test whether lipofection efficiency could be enhanced in gastrointestinal cell lines by the growth-promoting effect of insulin. 2. To assess the effect of insulin on lipofection efficiency and the cell cycle, expression of green fluorescent protein (GFP) and DNA distribution in gastric (MKN1), colonic (HT29) and pancreatic (BxPC3) carcinoma cell lines was analysed using flow cytometry. 3. The percentage of positive cells with GFP was significantly higher in MKN1 cells in culture medium with 5 mg/mL insulin than without insulin, whereas the percentage was the same in HT29 and BxPC3 cells with insulin as without insulin. The percentage of S phase fraction MKN1 cells with insulin was greater than without insulin, whereas the percentage of S phase fractions of HT29 and BxPC3 cells was the same with or without insulin. Lipofection efficiency correlated with the percentage of S phase fraction. 4. Insulin has the potential to enhance efficiency of lipofection into a sensitive cell line by increasing cellular proliferation.