Down-regulation of the desmosomal cadherin desmocollin 3 in human breast cancer

In previous studies using cDNA microarray analysis, we have identified an e xpressed sequence tag which is consistently down-regulated in six human bre ast tumor cell lines. In the current study, we have determined this tag to be part of the mRNA sequence of human desmocollin 3, a member of the cadher in superfamily of proteins and an integral component of desmosomes. Desmoso mes are sites of adhesion between adjacent cells in layers of epithelia, as well as in some non-epithelial tissues, and play an important role in the maintenance of tissue structure. Northern analysis, quantitative real-time polymerase chain reaction assay and Western blot analysis showed that desmo collin 3 is present in normal and immortalized human mammary epithelial cel ls, but consistently exhibits a significant, and often complete, down-regul ation in breast cancer cell lines and primary breast tumors, both at the mR NA and protein levels.