Aim and Background. Gene silencing effect of siRNA significantly depends upon an appropriate method to introduce it into the cells. In the present study, the effect of liposomes on ¹⁷⁷Lu-siRNA delivery into colon cancer cells has been studied quantitatively.

 Material and Methods. siRNA was conjugated with p-SCN-Bn-DTPA and labeled with lutetium. After being purified with Vivaspin and Sephadex G25 columns, ¹⁷⁷Lu-siRNA complexes were evaluated for purity and integrity using ITLC and PAGE, respectively. Labeled siRNAs were transfected into colon cancer cells using Lipofectamine and siPORT Neo FX. Then, percentage of the transfection was quantitatively calculated with a gamma counter. For the evaluation of cytotoxic effects of the labeled siRNA, microscopic photographs and cell counting were used.

 Results. ITLC showed that the purity of ¹⁷⁷Lu-siRNA complex products were in excess of 95%. The percentage of the transfected ¹⁷⁷Lu-siRNA complexes with Lipofectamine was significantly higher compared to that of siPORT Neo FX (P < 0. 01). Cell counting and microscopic photographs indicated that ¹⁷⁷lu-siRNA complex targeting IGF-1R had significantly cytotoxic effect on the understudied cells compared to the control groups (P < 0.001).

Conclusion. The present study shows that efficiency of the lipofectamine in transfection of the ¹⁷⁷Lu-siRNA into colon cancer cells is more than siPORT Neo FX, and ¹⁷⁷Lu-siRNA targeting IGF-1R has cytotoxic effect on colon cancer cells.