ROS-Triggered Autophagy Is Involved in PFOS-Induced Apoptosis of Human Embryo Liver L-02 Cells

Abstract

The liver is the primary target organ for perfluorooctane sulphonate (PFOS), a recently discovered persistent organic pollutant. However, the mechanisms mediating hepatotoxicity remain unclear. Herein, we explored the relationship between reactive oxygen species (ROS) and autophagy and apoptosis induced by PFOS in L-02 cells, which are incubated with different concentrations of PFOS (0, 50, 100, 150, 200, or 250 μmol/L) for 24 or 48 hrs at 37°C. The results indicated that PFOS exposure decreased cell activities, enhanced ROS levels in a concentration-dependent manner, decreased mitochondrial membrane potential (MMP), and induced autophagy and apoptosis. Compared with the control, 200 μmol/L PFOS increased ROS levels; enhanced the expression of Bax, cleaved-caspase-3, and LC3-II; induced autophagy; decreased MMP; and lowered Bcl-2, p62, and Bcl-2/Bax ratio. The antioxidant N-acetyl cysteine (NAC) protected MMP against PFOS-induced changes and diminished apoptosis and autophagy. Compared with 200 μmol/L PFOS treatment, NAC pretreatment reversed the increase in ROS, Bax, and cleaved-caspase-3 protein caused by PFOS, lowered the apoptosis rate increased by PFOS, and increased the levels of MMP and Bcl-2/Bax ratio decreased by PFOS. The autophagy inhibitor 3-methyladenine and chloroquine decreased apoptosis and cleaved-caspase-3 protein level and increased the Bcl-2/Bax ratio. In summary, our results suggest that ROS-triggered autophagy is involved in PFOS-induced apoptosis in L-02 cells.

PFAS Molecules: A Major Concern for the Human Health and the Environment

“…Selected in vitro studies (published since 2010) exploring toxic effects of PFAS are summarised in Table 4. Majority of the presented in vitro studies investigated the impact of PFOA and/or PFOS, while the main observed effects were on thyroid [213][214][215][216] and hepatic cells [217][218][219][220][221]. In vitro exposure of thyroid cells to different PFAS was shown to have varied thyroid-disrupting effects.…”

“…As a result, the authors came to the conclusion that short-chain PFCs had no acute cytotoxic effect on thyroid cells in vitro [216]. Some of the in vitro studies explored liver toxicity of the PFAS by investigating the occurrence of the oxidative stress on different hepatic cell lines [218,219], as well as apoptosis/autophagy [219] and cholesterol/bile acids level [221]. The impact of PFOS, PFOA, PFHxS, PFNA, PFDA, PFUnA, and PFDoA on the same cell line (HepG2) has been tested.…”

“…Other studies also explored the link between PFOA/PFOS and oxidative stress/apoptosis in different liver cells. Zeng et al (2021) tested the influence of PFOS on human embryo liver L-02 cells. Reduced cell activity was observed, as well as increased ROS levels in a concentration-dependent manner.…”

“…Impaired mitochondrial membrane potential (MMP), as well as elevated autophagy and apoptosis were observed, together with the increased expression of Bax, cleaved-caspase-3, and LC3-II. The authors concluded that ROS-dependent autophagy might be the cause of PFOS-induced apoptosis in L-02 cells [219]. Other mechanisms underlying PFAS-induced liver injury were also investigated.…”

Associations between Exposures to Perfluoroalkyl Substances and Diabetes, Hyperglycemia, or Insulin Resistance: A Scoping Review

“…Even with increased affinity for these nuclear receptor pathways, another in vitro study has shown that PFAS exposures to hepatic cells reduce expression of phase I and II detoxification enzymes, including cytochrome P450s (1A2, 2C19, and 3A4), glutathione-S-transferase (M1), and UDP-glucuronosyltransferase (1A1) [ 35 ]. Pathologically, both in vivo and in vitro studies have found increased oxidative stress, autophagy, or apoptosis due to PFAS exposures [ 36 , 37 , 38 , 39 ]. Despite these many recent advances, many of the health consequences of PFAS exposures are not fully understood, and additional studies are required to comprehensively characterize PFAS toxicity.…”