A colorimetric immunoassay for the detection of E-cadherin and calcinoembryonic antigen (CEA) expression on human colon carcinoma cell lines in vitro

An immunohistochemical assay, using 96-well microtiter plates and based on the avidin-biotin peroxidase reaction, was developed for the quantitation of E-cadherin and CEA expression on HT-29 and SW620 colon carcinoma cells. The optical density of the generated dye was measured after solubilization with alkaline SDS solution. The staining procedure was evaluated with respect to reproducibility (coefficient of variation and intra-class correlation coefficient). On HT-29 cells the level of agreement for both E-cadherin and CEA were substantial, on SW620 cells almost perfect. The method allows testing compounds for their differentiation inducing capacity in screening programmes on the basis of protein marker expression.