Discovery of naturally occurring ESR1 mutations during acquisition of resistance to endocrine therapy in widely used estrogen receptor positive breast cancer cell lines [ChIP-Seq]

We report the first discovery of naturally occurring ESR1Y537C and ESR1Y537S mutations in MCF7 and MCF7 ESR1-positive cell-lines after acquisition of resistance to long-term-estrogen-deprivation (LTED) and subsequent resistance to fulvestrant (ICIR). Examination of ER binding in breast cancer cell lines with and without ESR1 mutations