ABSTRACT
The in vitro effects of docetaxel on the human colon carcinoma cell lines-HT-29 and SW620 were studied by measuring the expression of the differentiation markers E-cadherin and CEA with a recently developed immunohistochemical assay. Docetaxel was shown to increase the expression of E-cadherin and CEA in the low concentration range of 3 x 10(-10) M - 3 x 10(-9) M for HT-29 cells and 0.6 - 3 x 10(-9) M for SW620 cells. Docetaxel strongly increased CEA (270%) and E-cadherin (160%) expression in HT-29 cells, compared with both marker expression in SW620 cells (60%). E-cadherin and CEA expression were found to be inversely correlated to the antiproliferating potential of docetaxel, which inhibits the cell proliferation of HT-29 cells at an IC50 of 6 x 10(-10) M and of SW620 cells at 8 x 10(-10) M. The data suggest, that in addition to its antiproliferative activity docetaxel also exhibits a strong differentiation inducing capacity at concentrations < 10(-9) M in vitro. These docetaxel effects were more pronounced on the differentiated HT-29 cells than on the poorly differentiated SW620 cells.
Subject(s)
Antineoplastic Agents, Phytogenic/pharmacology , Cadherins/analysis , Carcinoembryonic Antigen/analysis , Colonic Neoplasms/drug therapy , Paclitaxel/analogs & derivatives , Taxoids , Cell Division/drug effects , Colonic Neoplasms/chemistry , Colonic Neoplasms/pathology , Docetaxel , Dose-Response Relationship, Drug , Humans , Paclitaxel/pharmacology , Tumor Cells, CulturedABSTRACT
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.
