New approaches to molecular diagnostics, identification of differentially expressed genes in breast cancer cell lines using cDNA aray hybridization and sequence analysis

grantor: University of TorontoIn initial efforts to identify genes which may play roles in breast tumourigenesis, 950 cDNA clones were previously isolated by differential methods. DNA sequencing and homology searches of 208 cDNAs revealed 85 known genes and 67 unknown genes comprising 34 ESTs and 33 novel cDNAs showing no homology within the Genbank database. Expression profiles of 93 unique cDNAs were generated by array hybridization for breast cancer cell lines HTB126, HTB26 and MCF-7. Subsequent Northern analysis confirmed expression patterns of six cDNAs, three of which show differential expression and have not been previously implicated in cancer. T1F4/ribophorin II shows increased expression in HTB26 cells. The biological significance of this expression may relate to binding of ribophorin to the antiapoptotic molecule DAD1. cDNA clone T3B4 represents an unknown gene expressed at higher levels in estrogen receptor negative, invasive cell lines, suggesting a link between T3B4 expression and breast cancer progression. An additional novel cDNA, T3H3, appears to be upregulated in HTB26 cells. Using a combination of sequence analysis and gene expression fingerprinting, a number of cDNAs worthy of further investigation in the context of breast cancer were identified.M.Sc