Systematic immunohistochemical analysis of the expression of CD46, CD55, and CD59 in colon cancer.

CONTEXT:The expression of membrane-bound complement regulatory proteins (mCRPs) that inhibit the complement system in normal tissues is essential for self-protection against an autologous immune reaction. However, the expression patterns of mCRPs, including CD46, CD55, and CD59, are inconsistent in different types of cancer cells. OBJECTIVES:To determine whether CD46, CD55, and CD59 are differentially expressed in neoplastic and adjacent normal colon tissues and to assess their clinical significance. DESIGN:Immunohistochemistry was performed on tissue microarrays of cancerous and adjacent normal colon tissues. RESULTS:The expression levels of CD46, CD55, and CD59 were significantly higher in colon cancer tissues compared with the normal adjacent colon tissues. We found that the expression levels of CD55 and CD59 correlated with the grade of differentiation in colon cancers. In addition, the expression of CD55 and CD59 was greater in stage III and stage IV colon cancers than in stage I and stage II cancers according to staging by the TNM classification. CONCLUSIONS:CD46, CD55, and CD59 are up-regulated in colon cancer. Specifically, CD55 and CD59 are of clinical relevance to differentiation and TNM staging of colon cancer. These data suggest that CD46, CD55, and CD59 have the potential to be used for molecular staging diagnoses and for colon cancer therapies.