High-mobility group A1 proteins may be involved in estrogen receptor status of breast cancer

Breast cancer is one of the most common of cancers in woman. About 316,700 new cases were diagnosed as breast cancer in US woman in 2019 and 41,760 were predicted to die from it (1). Breast cancer has a characteristic of therapy-targeting receptors: hormone receptors (HR) that are estrogen receptor [ER: human ERα protein (NCBI protein accession NP_000116.2) encoding the ESR1 gene (RefSeq NM_000125.4)], and progesterone receptor (PR). In addition to ER and PR is the tyrosine kinase-type receptor, erythroblastic oncogene B2 (ERBB2), also called HER2. These receptors are important for managing breast cancer in advanced stages as well as early stages. Accordingly, breast cancer is categorized into three subtypes: HR+/ERBB2–; ERBB2+ (HR+ or HR–); and triple-negative (ER–, PR–, ERBB2–). Seventy percent of breast cancer cases respond to anti-estrogen therapy through ER positivity, but one-third develop resistance within 15 years. Mutations of the ESR1 gene have been frequently found in these cases. ERBB2+ (also called HER2+) is found in 20–25% of breast cancers and a humanized monoclonal antibody raised against ERBB2 called trastuzumab was developed. Estimated overall survival rate was 92% for trastuzumab plus doxorubicin and cyclophosphamide followed by docetaxel treatment. Triple negative (ER–, PR–, ERBB2–) accounts for 10–20% of breast cancers with the worst prognosis of the three types (2)