Multiple Targets and Pathways Non-Monotonically Regulate Lung Squamous Cell Carcinoma Migration in Response to Phthalates

Comprehensive Summary

This study investigated how phthalates, widely used plasticizer chemicals, may influence the progression of Lung Squamous Cell Carcinoma. Using network toxicology, machine learning, molecular docking, and laboratory experiments, the researchers identified four key genes linked to phthalate-associated LUSC: ANXA5, CDK4, MMP1, and SRD5A1. These genes are involved in cancer-related processes such as cell growth, invasion, hormone metabolism, and immune regulation. A diagnostic model based on these four genes showed strong predictive accuracy with an AUC of 0.96, suggesting that the gene signature may serve as a reliable biomarker for LUSC. Molecular docking simulations also suggested that benzyl butyl phthalate (BBP), a common phthalate, could bind directly to proteins encoded by ANXA5 and SRD5A1, supporting the possibility that phthalates interfere with cellular signaling pathways involved in cancer progression. The key experimental finding was that low, non-toxic concentrations of BBP promoted the migration of lung squamous carcinoma cells in both H226 and NCI-H1703 cell lines, which may indicate an increased metastatic potential. At 0.1 μM, BBP significantly increased the expression of ANXA5 and SRD5A1 and enhanced cell migration, while higher doses either reduced or reversed some of these effects. This “low-dose activation and high-dose inhibition” pattern is characteristic of endocrine-disrupting chemicals. The study also found that phthalate-associated gene changes were linked to altered immune cell infiltration, particularly increased neutrophils and M2 macrophages, which are associated with tumor progression. Overall, the researchers concluded that BBP may promote LUSC progression through multiple pathways involving cell migration, steroid metabolism, membrane signaling, and immune microenvironment changes, although further studies are needed to confirm direct causal effects in humans.

Outcomes and Implications

The findings of this study have several potential clinical implications for Lung Squamous Cell Carcinoma. The identification of ANXA5, CDK4, MMP1, and SRD5A1 as key genes associated with phthalate exposure suggests that these markers could eventually aid in early detection, risk stratification, or prognosis assessment in patients with LUSC. The strong diagnostic performance of the four-gene model also raises the possibility of developing biomarker panels for identifying environmentally linked tumor subtypes. In addition, the observation that low, non-cytotoxic concentrations of BBP enhanced cancer cell migration highlights the potential role of chronic environmental phthalate exposure in promoting tumor aggressiveness and metastasis, even at doses previously considered relatively harmless. Clinically, these findings support growing concerns about endocrine-disrupting chemicals as modifiable environmental risk factors and emphasize the importance of exposure reduction strategies, particularly in high-risk populations such as smokers or individuals with occupational exposure to plastics. The study also identifies pathways related to steroid metabolism, immune regulation, and membrane signaling as possible therapeutic targets, although further in vivo and clinical validation is required before these findings can be translated into patient care.