Integration of ERα-PELP1-HER2 signaling by LSD1 (KDM1A/AOF2) offers combinatorial therapeutic opportunities to circumventing hormone resistance in breast cancer

LSD1, an epigenetic modifier, and PELP1, an estrogen receptor co-activator, integrate estrogen receptor ER alpha and HER2 receptor tyrosine kinase signaling to promote aromatase expression and hormone resistance in a preclinical model of post-menopausal breast cancer. In the previous issue of Breast Cancer Research, Cortez et al. show, for the first time, that knockdown or drug-mediated inhibition of PELP1 or LSD1 suppresses LSD1-mediated transcriptionally activating histone marks at ERa target genes, inhibits aromatase gene expression, and sensitizes hormone refractory breast cancer cells to tamoxifen or letrozole treatments. The relevance of PELP1-LSD1 signaling to other nuclear hormone receptor-dependent cancers and structural considerations for the selective drug targeting of LSD1 are further discussed in this editorial.