Malignant Transformation of Human Uroepithelial Cells Induced by Long-Term Exposure to a Disinfection Byproduct2,6-Dichlorobenzoquinone

Halobenzoquinones
(HBQs), a class of water disinfection byproducts
(DBPs), have emerged as potential bladder carcinogens. However, evidence
regarding the long-term health effects of HBQ exposure and their potential
to induce malignant transformation remains limited. Here, we examined
the chronic effects of 2,6-dichlorobenzoquinone (2,6-DCBQ) exposure
on human immortalized uroepithelial cells (SV-HUC-1), with a focus
on malignant transformation. Cells were continuously exposed to a
noncytotoxic concentration of 2,6-DCBQ for over three months. The
long-term transformed cells exhibited cellular and nuclear pleomorphism
and anchorage-independent cell growtha hallmark of cancer
cell transformation. Proteomic analysis identified 60 differentially
expressed proteins (DEPs), 20 of which are strongly associated with
specific pathways of urinary bladder and urothelial cells. Enrichment
analysis highlighted the actin cytoskeleton and extracellular matrix
(ECM)–receptor interaction pathways. These molecular changes
were supported by immunofluorescence assay, revealing filamentous
actin disorganization and vinculin mislocalization in 2,6-DCBQ-treated
cells. Together, these results suggest that cytoskeletal destabilization
and adhesion collapse are key features associated with 2,6-DCBQ-induced
malignant transformation, indicating that chronic exposure to low-level
waterborne HBQs is associated with human bladder carcinogenesis.