BRCA2-deficient ER-positive/HER2-negative MCF7 cell lines

In this study, we investigated the estrogen receptor (ER) signaling pathway in BRCA2-deficient breast cancers using both clinical and in vitro approaches. For our in vitro experiments, we generated two BRCA2-deficient, ER-positive/HER2-negative cell lines from MCF7 cells (obtained from American Type Culture Collection, Manassas, VA) using CRISPR-Cas9-mediated targeting of distinct BRCA2 exons. The resulting clones were designated M1-4 and M2-6.To examine temporal effects, we prepared two batches of each cell line: low-passage cells (less than or equal to 2 months) and high-passage cells (greater than or equal to 8 months). Using these cell lines, we analyzed the expression of proteins involved in the ER signaling pathway and assessed sensitivity to both the PARP inhibitor olaparib and the selective estrogen receptor modulator tamoxifen. DNA sequencing was performed on parental MCF7 cells and both low- and high-passage batches of M1-4 and M2-6 clones.