Isolation of chromosome 6-encoded differentially expressed genes associated with breast cancer cell lines MDA-MB-231 and MDA/H6 by cDNA microarray

The loss of heterozygosity and chromosomal alterations were frequently observed on human chromosome 6 in cancers. In this study, we analyse the relative RNA levels between the parental breast cancer cell line MDA-MB-231 and the chromosome 6-mediated suppressed cell subline MDA/H6 using high-density gene filters containing more than 5,000 genes. Two cell lines were cultured under the same growth conditions for RNA preparation. Total RNA was reverse transcribed into first-strand cDNA in the presence of a³³P-dCTP. Approximately 10E8cpm of the labelled cDNAs were used for hybridization. Signal intensities from the hybridization were used to compare the relative levels of gene expression. Our analysis revealed approximately 100 genes were differentially expressed between the two cell lines. We identified 10 differentially expressed genes encoded on human chromosome 6, including genes encoding insulin-like growth factor 2 receptor, 5T4 oncofetal antigen and protein-tyrosine kinase 7. These results should facilitate our understanding of the molecular basis of the chromosome 6-mediated suppression of breast cancer.