Bisphenol A induces osteoporosis by targeting LAMA4 and OLR1: Novel insights into environmental bone toxicity.

BACKGROUND

Bisphenol A (BPA), a prevalent endocrine-disrupting chemical, is associated with osteoporosis (OP). However, the key molecular targets and mechanisms remain unclear.

METHODS

A training set of 161 public transcriptomic samples (75 OP, 86 Controls) was used for network toxicology and 113 algorithm combinations, with an independent validation set of 20 samples (10 OP, 10 Controls, GSE7429). Additional clinical validation included label‑free proteomic profiling of bone tissue (n = 10; 5 OP, 5 Controls) and RNA sequencing of peripheral blood mononuclear cells (PBMCs) (n = 12; 6 OP, 6 Controls). Single‑cell RNA sequencing mapped cellular expression of candidate genes. Molecular docking predicted potential binding interactions. In vitro functional assays were conducted in mouse bone marrow stromal cells (BMSCs) using a non-cytotoxic BPA concentration (10 μg/mL).

RESULTS

We identified and validated a set of core dysregulated genes in OP. Proteomic profiling of bone tissue revealed significant changes in five proteins: LAMA4 (log2FC = 0.971, p = 0.011), MYH7B (log2FC = 0.902, p = 0.035), FLNA (log2FC = 0.729, p = 0.013), and LAMB1 (log2FC = 0.917, p = 0.038) were upregulated, while OLR1 (log2FC = -0.954, p = 0.027) was downregulated. Notably, all these proteins except FLNA showed consistent dysregulation trends at the mRNA level in parallel transcriptomic analysis. Single-cell analysis revealed specific enrichment of LAMA4 in BMSCs, with LAMA4⁺ BMSCs exhibiting distinct intercellular communication patterns. Molecular docking computationally predicted potential binding interactions between BPA and several core targets. Functionally, non-cytotoxic BPA exposure significantly inhibited osteogenic differentiation of BMSCs, accompanied by downregulation of osteogenic markers. Among these, only LAMA4 and OLR1 showed BPA‑responsive expression changes during osteogenic differentiation that matched the direction observed in clinical multi‑omics data. Post-hoc power analysis indicated > 80% power to detect the observed fold changes at α = 0.05.

CONCLUSION

This study identifies LAMA4 and OLR1 as potential novel toxicity targets through which BPA disrupts bone homeostasis. These findings provide mechanistic insights into environmental chemical-induced bone fragility and support the inclusion of skeletal endpoints in chemical risk assessment.