Impact of AdipoR1 expression on breast cancer development

Adiponectin serum levels have been shown to be inversely correlated with breast cancer risk. The protein is believed to act through adiponectin receptor 1 (AdipoR1) and has been suggested to play an important role in cancer development. While AdipoR1 is known to be expressed in invasive tumors, its role in DCIS remains elusive. We therefore investigated AdipoR1 expression in both invasive and preinvasive breast cancer.

Tissue microarrays were established from paraffin-embedded archived tissues which contained 104 invasive breast cancers with adjacent preinvasive component (DCIS) as well as 96 preinvasive breast cancers. AdipoR1 expression was investigated by immunohistochemistry and correlated with clinical and tumor parameters.

AdipoR1 was detected in stromal and epithelial components of both invasive and preinvasive breast cancer. However, stromal and epithelial immunoreactivity for AdipoR1 was significantly higher in invasive breast cancer compared to preinvasive DCIS (p<0.001 and p=0.009). Within DCIS, AdipoR1 expression was inversely correlated with tumor size (r=-0.238, p=0.033). Menopausal status showed no influence on AdipoR1 expression.

The altered expression of AdipoR1 in invasive breast cancer compared to DCIS suggests that the receptor-binding protein adiponectin might exert growth inhibitory effects that are overcome in transformation of preinvasive to invasive breast cancer.