Evidence of promoting effects of 6:2 Cl-PFESA on hepatocellular carcinoma proliferation in humans: An ideal alternative for PFOS in terms of environmental health?

ABSTRACT

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are synthetic chemicals, encompassing compounds like perfluorooctane sulfonate (PFOS), which have widespread applications across various industries, including food packaging and firefighting. In recent years, China has increasingly employed 62 Cl-PFESA as an alternative to PFOS. Although the association between PFAS exposure and hepatocellular carcinoma (HCC) has been demonstrated, the underlying mechanisms that promote HCC proliferation are uncleared. Therefore, we aimed to investigate the effects and differences of PFOS and 62 Cl-PFESA on HCC proliferation through in vivo and in vitro tumor models. Our results reveal that both PFOS and 62 Cl-PFESA significantly contribute to HCC proliferation in vitro and in vivo. Exposure led to reduced population doubling times, enlarged cell colony sizes, enhanced DNA synthesis efficiency, and a higher proportion of cells undergoing mitosis. Furthermore, both PFOS and 62 Cl-PFES) have been shown to activate the PI3K/AKT/mTOR signaling pathway and inhibit necroptosis. This action consequently enhances the proliferation of HCC cells. Our phenotypic assay findings suggest that the tumorigenic potential of 62 Cl-PFESA surpasses that of PFOS; in a subcutaneous tumor model using nude mice, the mean tumor weight for the 62 Cl-PFESA-treated cohort was 2.33 times that observed in the PFOS cohort (p < 0.01). Despite 62 Cl-PFESA being considered a safer substitute for PFOS, the pronounced effects of this chemical on HCC cell growth warrant a thorough assessment of hepatotoxicity risks linked to its usage.