AGR2 associates with HER2 expression predicting poor outcome in subset of estrogen receptor negative breast cancer patients

Expression of the AGR2 oncogene was shown to be associated with estrogen receptor positive tumors. This gene contributes to enhanced cellular proliferation, drug resistance, metastasis development and may also serve as a predictor of poor prognosis. However, our analysis of AGR2 expression in a subset of estrogen-receptor negative tumors revealed that AGR2 could also be upregulated in hormone-independent manner. AGR2 expression was shown to be significantly increased in HER2 positive breast tumors on both the mRNA and the protein level. Moreover, in a subset of estrogen- and progesterone-receptor negative and simultaneously HER2-positive cases, increased AGR2 expression significantly correlated with worse patient prognosis. Subsequent analysis of independent data sets either collected in our institute or obtained from Oncomine cancer microarray database confirmed all these findings.