Research Links Common Chemicals to Altered Breast Development Risks

Recent research from Tufts University School of Medicine and Boston University uncovers a concerning relationship between exposure to certain chemicals, notably multiple bisphenols, and alterations in the development of human breast tissue. By utilizing advanced human breast organoids derived from young female donors, this study suggests that these exposures could trigger molecular changes linked to an increased risk of breast diseases later in life.

These findings pave the way for further investigation into whether the molecular changes induced by these chemicals persist within human tissues and if they may serve as biomarkers for assessing breast cancer risk. Dr. Charlotte Kuperwasser, a professor of developmental, molecular, and chemical biology at Tufts, who is a senior author on the study, expressed that validation of this research could shift current perspectives on cancer prevention significantly. The study was published in PNAS under the title “Environmental chemical mixtures reprogram mammary epithelial development to epigenetic states associated with breast cancer”. Co-first authors include PhD students Meadow Parrish and Meloryn Seraj from the Tufts Graduate School of Biomedical Sciences.

The research draws attention amid growing concern about the role of endocrine-disrupting chemicals (EDCs) in potentially contributing to the risk of breast cancer, particularly in young women. EDCs are prevalent in our environment—found in air, water, food, and consumer products—and exposure can begin prenatally and persist throughout life. The authors highlight concerning epidemiological trends indicating that developmental exposure to EDCs might be linked to the rising rates of hormone-sensitive cancers, including breast cancer.

Kuperwasser highlighted that breast tissue undergoes significant development beyond infancy, with critical changes during puberty and pregnancy making it particularly vulnerable to environmental influences like chemical exposure. To capture this complexity more accurately, the researchers turned to three-dimensional breast organoids, which maintain various breast cell types and can mimic human breast tissue development more closely than traditional models.

The team grew these organoids from breast tissue sourced from 13 healthy young women and exposed them to a combination of individual chemicals and mixtures—including various EDCs and known carcinogens—over a development period of three weeks. They then examined the resulting molecular changes, which notably included alterations in gene expression and DNA modifications. The researchers developed an AI-enhanced 3D human breast organoid high-content screening (3D-HCS) platform, enabling precise quantification of developmental disruptions and morphogenetic changes linked to chemical exposure.

Among the variety of chemicals tested, the most significant disturbances in tissue development arose from a mixture of bisphenols—specifically BPA, BPS, and BPF. When these compounds were administered in low concentrations, similar to those detected in human biomonitoring studies, they caused notable disruptions in the organoids' development across almost all samples analyzed. The researchers reported that the bisphenol mixture led to transcriptional changes characterized by alterations in extracellular matrices, epithelial plasticity, and shifts toward epithelial-mesenchymal transition, alongside widespread remodeling of DNA methylation patterns.

Kuperwasser remarked on the deliberate choice of chemical concentrations that reflect realistic exposure scenarios rather than the high doses employed in many toxicology investigations. She emphasized that human exposure frequently involves multiple chemical agents occurring concurrently.

When the team compared the molecular changes from exposure to the bisphenol mixture to molecular data from human breast cancers, they found similarities with patterns seen in patients suffering from invasive lobular carcinoma, a type of breast cancer often challenging to detect via traditional screening methods. They deduced that these exposure-induced transcriptional signatures and DNA methylation alterations might leave lasting molecular markers that create conditions typical of cancer-prone tissues.

While the study does not conclusively prove that these chemicals cause cancer or elucidate the mechanisms behind the observed molecular changes, it does present a novel framework for examining the impact of environmental exposures on normal human tissue prior to the onset of malignancy. Kuperwasser noted that traditionally, cancer risk has largely been attributed to genetic mutations and direct DNA damage; however, this research introduces the idea that environmental factors could subtly influence normal tissue development, resulting in changes that increase the risk of cancer over time.

If corroborated in broader studies, these stable molecular alterations could potentially act as biological indicators of past environmental exposure, presenting opportunities for earlier identification of individuals at higher breast cancer risk and enabling more informed, targeted screening strategies.

Looking ahead, the researchers call for extensive studies involving a more diverse set of participants and a wider spectrum of chemicals to ascertain the applicability of their findings and to explore the potential connection between the observed changes in organoids and breast disease in actual human populations.