Assessing the double-edged of extracellular signal-regulated kinase/CCAAT-enhancer-binding protein beta signaling pathway in arsenic-induced skin damage and its potential foodborne interventions.

Arsenic exposure is a major environmental public health challenge worldwide. As typical manifestations for arsenic exposure, the pathogenesis of arsenic-induced skin lesions has not been fully elucidated, as well as the lack of effective control measures. In this study, we first determined the short-term and high-dose arsenic exposure can increase the apoptosis rates, while long-term low-dose arsenic exposure decrease the apoptosis rates. Then, the HaCaT cells with knockdown and overexpression of CCAAT-enhancer-binding protein ß (CEBPB) and extracellular signal-regulated kinase (ERK) were constructed. The results demonstrate that knockdown of CEBPB and ERK can reduce NaAsO2 -induced cell apoptosis by inhibiting ERK/CEBPB signaling pathway and vice versa. Further cells were treated with Kaji-Ichigoside F1 (KF1). The results clearly show that KF1 can decrease the arsenic-induced cell apoptosis rates and the expression of ERK/CEBPB signaling pathway-related genes. These results provide evidence that ERK/CEBPB signaling pathway acts as a double-edged sword in arsenic-induced skin damage. Another interesting finding was that KF1 can alleviate arsenic-induced skin cell apoptosis by inhibiting the ERK/CEBPB signaling pathway. This study will contribute to a deeper understanding of the mechanisms of arsenic-induced skin cell apoptosis, and our findings will help to identify a potential food-borne intervention in arsenic detoxification.

Inorganic arsenic promotes apoptosis of human immortal keratinocytes through the TGF-ß1/ERK signaling pathway.

Chronic exposure to high-dose inorganic arsenic through groundwater, air, or food remains a major environmental public health issue worldwide. Apoptosis, a method of cell death, has recently become a hot topic of research in biology and medicine. Previous studies have demonstrated that extracellular signal-regulated kinase (ERK) is related to arsenic-induced apoptosis. However, the reports are contradictory, and the knowledge of the above-mentioned mechanisms and their mutual regulation remains limited. In this study, the associations between the TGF-ß1/ERK signaling pathway and arsenic-induced cell apoptosis were confirmed using the HaCaT cell model. The relative expressions of the indicators of the TGF-ß1/ERK signaling pathway, apoptosis-related genes (cytochrome C, caspase-3, caspase-9, cleaved caspase-3, cleaved caspase-9, and Bax), the mitochondrial membrane potential, and the total apoptosis rate were significantly increased (P < .05), while the expression of the antiapoptosis gene Bcl-2 was significantly decreased (P < .05) in cells of the group exposed to arsenic. Moreover, the results demonstrated that the ERK inhibitor (PD98059) and TGF-ß1 inhibitor (LY364947) could inhibit the activation of the ERK signaling pathway, thereby reducing the mitochondrial membrane potential, the total apoptosis rate, and the expression of pro-apoptosis-related genes in the cells, while the expression of the antiapoptosis gene Bcl-2 was significantly increased (P < .05). By contrast, the recombinant human TGF-ß1 could promote apoptosis of the HaCaT cells by increasing the activation of the ERK signaling pathway (P < .05). These results indicate that inorganic arsenic promotes the apoptosis of human immortal keratinocytes through the TGF-ß1/ERK signaling pathway.

Assessing the potential molecular mechanism of arsenite-induced skin cell senescence.

Arsenic exposure is a public health concern worldwide. Skin damage, as a typical lesion of arsenic exposure, the mechanism is still unknown. Studies have found that cellular senescence plays a key role in arsenic-induced skin damage, and the previous research found that the ERK/CEBPB signaling pathway may be an important molecular event of arsenic-induced skin cell senescence, but its specific mechanism is unknown. In this study, genetic engineering technology was used to construct stable HaCaT cell lines, and the role and mechanism of ERK/CEBPB signaling pathway in arsenic-induced HaCaT cell senescence were verified by knockdown and overexpression of ERK and CEBPB in both forward and backward. It was found that knockdown of CEBPB or ERK can downregulate the ERK/CEBPB signaling pathway and reduce arsenic-induced skin cell senescence. In contrast to knockdown, overexpression of CEBPB or ERK can upregulate the ERK/CEBPB signaling pathway and aggravate the senescence of skin cells caused by arsenic. These findings suggest that sodium arsenite can further promote SASP secretion and the expression of p53, p21 and p16 INK4a by activating the ERK/CEBPB signaling pathway, induce cell cycle arrest and trigger cellular senescence.

Assessing the Potential Value and Mechanism of Kaji-Ichigoside F1 on Arsenite-Induced Skin Cell Senescence.

Chronic exposure to inorganic arsenic is a major environmental public health issue worldwide affecting more than 220 million of people. Previous studies have shown the correlation between arsenic poisoning and cellular senescence; however, knowledge regarding the mechanism and effective prevention measures has not been fully studied. First, the associations among the ERK/CEBPB signaling pathway, oxidative stress, and arsenic-induced skin cell senescence were confirmed using the HaCaT cell model. In the arsenic-exposed group, the relative mRNA and protein expressions of ERK/CEBPB signaling pathway indicators (ERK1, ERK2, and CEBPB), cell cycle-related genes (p21, p16INK4a), and the secretion of SASP (IL-1α, IL-6, IL-8, TGF-ß1, MMP-1, MMP-3, EGF, and VEGF) and the lipid peroxidation product (MDA) were significantly increased in cells (P < 0.05), while the activity of antioxidant enzyme (SOD, GSH-Px, and CAT) was significantly decreased (P < 0.05), and an increased number of cells accumulated in the G1 phase (P < 0.05). Further Kaji-ichigoside F1 intervention experiments showed that compared to that in the arsenic-exposed group, the expression level of the activity of antioxidant enzyme was significantly increased in the Kaji-ichigoside F1 intervention group (P < 0.05), but the indicators of ERK/CEBPB signaling pathway, cell cycle-related genes, and SASP were significantly decreased (P < 0.05), and the cell cycle arrest relieved to a certain extent (P < 0.05). Our study provides some limited evidence that the ERK/CEBPB signaling pathway is involved in low-dose arsenic-induced skin cell senescence, through regulating oxidative stress. The second major finding was that Kaji-ichigoside F1 can downregulate the ERK/CEBPB signaling pathway and regulate the balance between oxidation and antioxidation, alleviating arsenic-induced skin cell senescence. This study provides experimental evidence for further understanding of Kaji-ichigoside F1, a natural medicinal plant that may be more effective in preventing and controlling arsenic poisoning.