Dependent receptor can transmit both positive signal: proliferation, differentiation or migration; and negative signal: apoptosis. It depends on the presence of its ligand. This study was performed to determine the effects of transfection of dependent receptors in human colon cancer cell lines.

Two dependent receptors (rearranged during transfection [RET]9 and RET51) were transfected into three human colon cancer cell lines: SW48, RKO and V400. Then, half of them were treated with glial cell line-derived neurotrophic factor (GDNF). Using ELISA and caspase assay, apoptosis was measured. Dose-response relation between GDNF and apoptosis was also analyzed. A pcDNA was used as an empty vector.

After transfection of RET51, apoptosis was increased in SW48 (70% with ELISA and 119% with caspase assay) and RKO (255% with ELISA and 106% with caspase assay) cell lines when compared with the pcDNA group. V400 cell line did not show increased apoptosis. Transfection of RET9 did not induce apoptosis in all of the three human colon cancer cell lines. Treatment with GDNF 12 hours after transfection of RET51 decreased apoptosis in SW48 (66% with ELISA and 60% with caspase assay) and RKO (39% with ELISA and 57% with caspase assay) when compared with the cell lines transfected with RET51 only. Apoptosis was down-regulated with increasing concentration of GDNF in RKO cell line.

This study showed that the apoptosis of human colon cancer cell line can be controlled by manipulating the dependent receptors and its ligands. We present the possibility of therapeutic method using dependent receptor in colon cancer.