Overexpressing ERBB4 in cultured mammary epithelial cells or adding the ERBB4 ligand neuregulin 1 (NRG1) to breast cancer cell cultures promoted the expression of genes regulated by YAP, such as CTGF.
The HER4 intracellular domain (4ICD) is a potent estrogen receptor (ERalpha) coactivator with activities in breast cancer and the developing mammary gland that appear to overlap with progesterone receptor (PgR).
We measured the expression of the type I growth factor receptor gene family [epidermal growth factor receptor (EGFR), c-erbB-2, c-erbB-3 and c-erbB-4] in a series of 365 unselected primary breast cancers.
These data indicate that EGFR as well as HER2 are prognostic factors of worse clinical outcomes, whereas HER3 and HER4 gene transcription is associated with better prognosis in high-risk early breast cancer.