Mechanism of YBX1/NOTCH1 Axis-Mediated Monocyte Apoptosis Under Benzene Exposure

Long-term exposure to the chemical industry pollutant benzene induces hematopoietic damage; however, the mechanism of this injury is unclear. Using an integrative RNA-seq analysis of benzene-exposed samples, we identified Y-box binding protein 1 (YBX1) and neurogenic locus notch homolog protein 1 (NOTCH1) as the most significantly dysregulated apoptosis-related molecules, prompting us to investigate their functional interplay. While neurogenic locus notch homolog protein 1 (NOTCH1) drives the progression of both benign and malignant disorders, the involvement of Y-box binding protein 1 (YBX1) despite being extensively characterized in tumorigenesis remains unexplored in the context of benzene-induced hematopoietic injury. This study examines the molecular mechanism of the YBX1/NOTCH1 axis in benzene-mediated monocyte apoptosis. Accordingly, we combined clinical data with RNA seqenceing (RNA-seq) analysis and examined the mechanistic basis of benzene-induced apoptosis in human monocytic leukemia cells using Cell Counting Kit-8 (CCK-8) cell viability assays, flow cytometry (FC), DNA pull-down coupled with liquid chromatography-tandem mass spectrometry (LC-MS), and western blotting (WB). Analysis of 1,4-BQ-treated THP-1 cells revealed that 1,4-Benzoquinone (1,4-BQ) upregulated NOTCH1/transcription coactivator BCL3 (BCL3) and downregulated YBX1/apoptosis regulator Bcl-2 (BCL2) in their gene profiles and protein levels. Furthermore, the differentially expressed genes were enriched in apoptotic pathways. Treatment with 1,4-BQ inhibited THP-1 cell proliferation, induced S-phase arrest, and triggered apoptosis in a concentration- and time-dependent manner. Knockdown of NOTCH1 or overexpression YBX1 significantly eliminated the inhibitory effects of 1,4-BQ on upregulated BCL3 and downregulated BCL2 expression. Furthermore, the inhibitory effects on apoptosis were considerably offset by YBX1 overexpression or NOTCH1 knockdown. YBX1 regulates BCL2/BCL3 by inhibiting NOTCH1, mediating benzene-induced monocyte apoptosis. Taken together, our results uncovered a critical role of YBX1/NOTCH1 in the benzene-induced monocyte apoptosis, which may have great potential as a biomarker and therapeutic target in benzene-induced hematotoxicity.