Differential gene expression in estrogen receptor negative breast cancer cells transfected with cDNA for estrogen receptor

N Ros, MSc, MM Brentani, PhD, MA Nagai, PhD

Departamento de Radiologia, Universidade de Sao Paulo, Sao Paulo, Brazil

The involvement of the estrogens on the proliferation of hormone-dependent breast tumor is well established. Estrogen acts by its receptor (ER) stimulating cellular proliferation and differentiation. ER status has been used as a prognostic and predictive marker in the clinical management of breast cancer patients. Polysaccharides and proteins compose the extracellular matrix (ECM). One of the ECM protein is laminin. The ECM and growth factors cooperate to regulate signaling pathways and gene transcription in adherent cells. In order to investigated whether hormonal control can be re-established in ER-negative cells and how it affects the signal transduction and the adhesion on laminin matrices, we analyzed the differential expression of genes in the estrogen-receptor negative MDA-MB231 breast carcinoma cell line compared with its clone transfected with the ER gene (S30). At the moment, 20 different arbitrary primers were combined with three anchorage primers and have been used at the analysis by differential display RT-PCR (DDRT-PCR). We have cloned and sequenced 79 different fragments. The search for similarity was done using the BLAST algorithm in the NCBI database. The differentially expressed transcripts showed homology with genes like aldo-keto reductase, IGFBP7, zinc finger protein, transcription factors and some KIAAs. The identification of genes differentially expressed after laminin adhesion might contribute to the understanding of the signal transduction pathways regulated by adhesion molecules. The phenotypic differences between hormone-responsive and hormone-unresponsive breast cancer could be explained by differences in gene expression. Supported by FAPESP

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Gene Expression, Part 2.

This presentation received an honorable mention in our poster contest and was recognized with the Symposium Presidents' Award for Scientific Excellence.