Inhibitors of
DNA binding/inhibitors of differentiation (Id)
protein family (Id-1, -2, -3 and -4) of helix-loop-helix
proteins have been shown to be involved in
carcinogenesis and are regarded as prognostic markers in several types of human
cancers. However, the roles of Id
proteins during
breast carcinoma progression remain unclear. The objective was to study the effects of Id
proteins in
breast cancer. The expression of Id-1,
Id-2, Id-3 and Id-4
proteins was examined in 122 dissected female human
breast carcinoma tissues and 22 normal female breast specimens by immunohistochemical assay and the relationship between Id staining and clinical pathological characteristics of
breast cancer was also analyzed. The over-expressed Id-1 and down-regulated Id-4
proteins were found both correlated with poorer differentiation and more aggressive behavior of the
tumor. Id-1
protein could be termed as a negative prognostic marker while Id-4
protein as a positive marker for patients with
breast carcinoma. Although the differentially expressed
Id-2 and -3 may be correlated with some clinical parameters, they could not be used as independent prognostic factors in human
breast cancer.