Unconventional isoquinoline-based SERMs elicit fulvestrant-like transcriptional programs in ER+ breast cancer cells. Journal Article

Local Library Link: Find It @ Loyola

Authors: Hancock, GR; Young, KS; Hosfield, DJ; Joiner, C; Sullivan, EA; Yildiz, Y; Lainé, M; Greene, GL; Fanning, SW
Article Title: Unconventional isoquinoline-based SERMs elicit fulvestrant-like transcriptional programs in ER+ breast cancer cells.
Abstract: Estrogen receptor alpha (ERa) is a ligand-dependent master transcriptional regulator and key driver of breast cancer pathology. Small molecule hormones and competitive antagonists favor unique ERa conformational ensembles that elicit ligand-specific transcriptional programs in breast cancer and other hormone-responsive tissues. By affecting disparate ligand binding domain structural features, unconventional ligand scaffolds can redirect ERa genomic binding patterns to engage novel therapeutic transcriptional programs. To improve our understanding of these ERa structure-transcriptional relationships, we develop a series of chemically unconventional antagonists based on the antiestrogens elacestrant and lasofoxifene. High-resolution x-ray co-crystal structures show that these molecules affect both classical and unique structural motifs within the ERa ligand binding pocket. They show moderately reduced antagonistic potencies on ERa genomic activities but are effective anti-proliferative agents in luminal breast cancer cells. Interestingly, they favor a 4-hydroxytamoxifen-like accumulation of ERa in breast cancer cells but lack uterotrophic activities in an endometrial cell line. Importantly, RNA sequencing shows that the lead molecules engage transcriptional pathways similar to the selective estrogen receptor degrader fulvestrant. This advance shows that fulvestrant-like genomic activities can be achieved without affecting ERa accumulation in breast cancer cells.
Journal Title: NPJ breast cancer
Publisher: Unknown  
Date Published: 2022