Chronic Exposure to Nanoplastics Alters Stem Cell Type-Specific Mechanisms, Promoting Cancer Development

Increasing levels of nanoplastics (NPLs) in the environment raise concerns about their effects on human health. We investigated the impact of the most prevalent NPLs, namely polyethylene terephthalate (PET) and polystyrene (PS), on stem cells (SCs), which persist for decades, support tissue function, and are often implicated in cancer development. Long-term exposure to both NPLs similarly affected mammary SC features with an enhanced self-renewal and altered 3D organization, without impairing differentiation capacity. Moreover, both NPLs significantly increased invasiveness and anchorage-independent growth, albeit molecular profiling revealed distinct signatures and mechanisms, indicating a shift towards a more aggressive phenotype. NPLs also synergized with BMP2 signaling, known to be disrupted by pollutants. These findings highlight how NPLs may contribute to early pre-neoplastic changes through distinct and cooperative mechanisms.