Environmental chemical mixtures reprogram mammary epithelial development to epigenetic states associated with breast cancer.

A low-dose mixture of bisphenols (BPA, BPS, and BPF) disrupts mammary organoid development and induces epigenetic changes linked to invasive lobular breast cancer.

• Why it matters: Understanding how environmental chemical mixtures influence human tissue development and cancer risk is limited, highlighting the need to clarify their mechanisms of action.
• What they did: A 3D human breast organoid screening platform was used to test diverse chemicals, revealing that the bisphenol mixture causes developmental disruptions and widespread DNA methylation remodeling associated with epithelial plasticity.
• The result: The exposure signature maps to ER+ luminal breast cancers, especially invasive lobular carcinoma, and is detectable in primary tumors and normal tissue, suggesting developmental exposures may establish cancer-relevant tissue states.