Mediator of DNA damage checkpoint 1 (MDC1) is a novel estrogen receptor co-regulator in invasive lobular carcinoma of the breast

We identified MDC1 as a putative novel transcriptional co-regulator of estrogen receptor alpha (ER) in models of invasive lobular carcinoma. In this study, our goal was to define the contribution of MDC1 to regulation of the ER transcriptome in ILC cell lines versus invasive ductal carcinoma cells. RNAseq was used to examine estrogen-driven changes in gene expression, with or without knockdown of MDC1, ER, or FOXA1. We compared gene expression in invasive lobular carcinoma cell lines (MM134/MDA MB 134VI, MM330/MDA MB 330) to invasive ductal carcinoma cell line HCC1428.