Clinically, MED1 expression highly correlates with poor disease-free survival of breast cancer patients, and recent studies have reported an increased frequency of MED1 mutations in the circulating tumor cells of patients after treatment.
MED1 mediates induction of cell proliferation and migration and the genes associated with it (JUN, FOS, EGFR, VEGF, MMP1, and ERBB4) in breast cancer, which is abrogated when used together with miR-191-inhibition.
Studies of the estrogen receptor (ER) coactivator protein Mediator subunit 1 (MED1) have revealed its specific roles in pubertal mammary gland development and potential contributions to breast tumorigenesis, based on coamplification of MED1 and HER2 in certain breast cancers.
Here, we've reported that knockdown of estrogen receptor coactivator MED1 sensitized fulvestrant resistance breast cancer cells to fulvestrant treatment.
Taken together, these results establish ARGLU1 as a new MED1-interacting protein required for estrogen-dependent gene transcription and breast cancer cell growth.
We found PBP gene amplification in approximately 24% (6/25) of breast tumors and approximately 30% (2/6) of breast cancer cell lines, implying that PBP gene overexpression can occur independent of gene amplification.