Engineering cancer cells to express heterologous antigen α-gal and induce the destruction of tumor cells depending on the complement cascade may be a promising strategy of tumor therapy. However, the feasibility and effect of using α-gal to induce colorectal adenocarcinoma cell lines cytolysis is not yet known. In this study, we evaluated α-gal expression's ability to sensitize human colorectal adenocarcinoma cell lines to complement attack in cell lines LoVo, SW620 and Ls-174T. Nearly all α-gal -expressing LoVo and SW620 cells were killed by human normal serum (NHS), but α-gal expression Ls-174T cells showed no significant lysis. We analyzed the expression levels of membrane-bound complement regulatory proteins (mCRPs) on the three cell lines, and their protective role in α-gal-mediated activation of the complement. LoVo show no expression of any of the three proteins. CD59 was strongly expressed by SW620 and Ls-174T. CD46 and CD55 varied between the two cell lines, CD46 on SW620 was only half the intensity of CD46 on Ls-174T. Ls-174T showed a notable expression of CD55, while expression of CD55 on SW620 was not detected. The sensitivity of Ls-174T expressing α-gal to NHS greatly increased following the down-regulation of CD46 and CD55 with shRNA. However, there is no increase in cell killing when CD59 expression was diminished. Our findings suggest that the use of α-gal as antigen to induce tumor cell killing may be a potential therapeutic strategy in colon cancer, and that CD55 plays a primary role in conferring resistance to lysis.