A Cell ELISA for the quantification of MUC1 mucin (CD227) expressed by cancer cells of epithelial and neuroectodermal origin.

Quantitative analysis of MUC1, a cell membrane associated mucin, expressed by intact cells of epithelial origin previously has been limited to flow cytometry, which requires using large quantities of cells and antibodies. Here, for the first time, we report the development of a novel Cellular-based Enzyme Linked Immunosorbent Assay (Cell ELISA) to quantify the expression of MUC1 by cell lines of epithelial and neuroectodermal origin using an antibody recognizing a specific tandem repeat found in the extracellular domain of MUC1. In contrast to flow cytometry, this method requires a much lower number of cells. We report here the results obtained from two variants of this Cell ELISA in live and fixed cells. We found that the Cell ELISA in live cells was not sensitive enough to detect a difference in MUC1 levels between the normal cells and tumor cells. However, we found that Cell ELISA in fixed cells followed by whole cell staining was a dependable method of MUC1 level detection in the normal and tumor cells showing significantly higher levels of MUC1 receptor in the tumor cells when compared to the normal controls. Therefore, we conclude that the Cell ELISA in fixed cells is an efficient method for quantifying the expression of MUC1 by epithelial and neuroectodermal cancer cell lines.