Analysis of Breast Cell‐Lineage Response Differences to Taxol Using a Novel Co‐Culture System

Abstract

We have established a new co-culture system in which normal human mammary epithelial cells (HMEC) and breast tumor cells (TC) were physically grown together. We hypothesized that cells in co-culture would generate gene expression profiles different from homogeneous cell populations. A second equally important question addressed was involved whether cell sensitivity to the antitumor agent Taxol (paclitaxel) differed in co-culture from conventional cultures. Preliminary data showed normal HMEC to be most sensitive to Taxol followed by estrogen receptor (ER) positive TC and ER negative TC, respectively. In this study, cells were transfected with green or red fluorescent proteins (FP) and co-cultured. Using deconvolution microscopy, co-cultured HMEC were observed to form focal, gland-like structures surrounded by TC derived from an invasive ductal carcinoma. Using a novel antibody-based, cell capture system coupled with differential trypsinization, we rapidly separated cell populations to perform RNA extractions (<2 h) in order to obtain expression profiles from still viable cells. Cell population purity was determined by telomerase activity. Microarray was utilized to analyze differential gene expression between parent cell lines and cells co-cultured, with or without Taxol at concentrations of 2.21 x 10−7 M. This study has significant relevance for breast cancer research on several levels. Our novel capture system allowed cells to be co-cultured and then quickly separated while maintaining ~90% viability. In addition, the use of microarray analysis allowed us to address the role co-culture may play in gene expression and responses by different breast cell populations to the antitumor agent Taxol.