Low Triphenyl phosphate concentrations fuel proliferation and migration of Hep3B, a hepatocellular carcinoma cell line

Abstract

Organophosphate flame retardants (OPFRs) have been widely used due to their unique properties. The OPFRs are mainly metabolized in the liver. However, whether the OPFRs in human plasma mediate progression of liver cancer remains unclear. Triphenyl phosphate (TPP) is one of the OPFRs that are most detected in environmental matrices. In this study, we performed CCK8, ATP, and EdU analyses to evaluate the effect of TPP (0.025–12.8µM concentration) on proliferation, invasion, and migration of Hep3B, a hepatocellular carcinoma cell line. Tumor-bearing mouses model were used for in vivo validation. The results showed that relative low concentrations (0.025 to 0.1µM) slightly increased cell proliferation and remarkably promoted cell invasion and migration of Hep3B. Animal experiments confirmed that TPP treatment significantly enhanced tumor growth in the xenograft HCC model. To explore the possible molecular mechanisms that might be mediating the actions of TPP on Hep3B, we profiled gene expression in groups treated with or without TPP (0.05 and 0.1µM) using transcriptional sequencing. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment and Protein-Protein Interaction (PPI) analyses demonstrated that pathways affected by differentially expressed genes (DEGs) were mainly in nuclear-transcribed mRNA catabolic processes, cytosolic ribosome and ATPase activity. 0.05 and 0.1µM TPP led to up-regulation of a series of genes including EREG, DNPH1, SAMD9, DUSP5, PFN1, CKB, MICAL2, SCUBE3, and CXCL8, but suppressed the expression of MCC. These genes have been shown to be associated with proliferation and movement of cells. Together, our findings suggest that relatively low concentrations of TPP could fuel the proliferation, invasion, and migration of hepatocellular carcinoma cells. Thus, TPP might be a risk factor in the progression of hepatocellular carcinoma in humans.