Effects of chronic arsenic exposure on energy metabolism in human keratinocytes

Abstract

Objective To explore the effects of chronic sodium arsenic (NaAsO2) exposure on energy metabolism in human keratinocytes (HaCaT). Methods Malignant transformation was induced when HaCaT cells were continuously exposed to an environmentally relevant level (0.1 μmol/L) of inorganic arsenic for 28 weeks, HaCaT and malignantly transformed cells were kept in Group of Chronic Disease and Environmental Genomics, School of Public Health, China Medical University. Basal oxygen consumption rate and extracellular acidification rate in control group and malignantly transformed group were measured by Agilent Seahorse XF24. Changes of glucose intake in malignantly transformed HaCaT cells were detected by 2-NBDG. Cells in logarithmic growth phase were collect, mRNA levels of key components in glycolytic pathwa [glucose-6-phosphate dehydrogenase (G6PD), phosphofructokinase (PFKL), glyceraldehyde-3-phosphate dehydrogenase (GAPDH)] and mitochondrial respiratory chain complex [NADH dehydrogenase iron-sulfur protein subunit 3 (NDUFS3), succinate dehydrogenase iron-sulfoprotein subunit (SDHB), cytochrome C (CYTC), CYTC oxidase subunit Ⅳ (COX4L1), ATP synthase F1 subunit (ATP5B), and ATP synthase F0 subunit (ATP5G1)] were determined by real-time quantitative PCR (RT-qPCR). Results The basal oxygen consumption rate of malignantly transformed group [(44.784 ± 10.159) pMoles/min] was lower than that of control group [(66.842 ± 15.756) pMoles/min, t = 4.914, P < 0.05]. The glucose intakes of malignantly transformed group (1.592 ± 0.410 for cells cultured without serum, and 1.631 ± 0.323 for cells cultured with serum) were significantly higher than those of control group (1.000 ± 0.334, 1.000 ± 0.196, t = 2.916, 4.068, P < 0.05). The mRNA levels of G6PD (0.555 ± 0.009), NDUFS3 (0.623 ± 0.031) and SDHB (0.702 ± 0.094) in malignantly transformed group were significantly lower than those of control group (1.000 ± 0.027, 1.000 ± 0.034, 1.000 ± 0.114, t = 23.690, 11.340, 2.814, P < 0.05); the mRNA levels of PFKL (1.787 ± 0.176), GAPDH (1.466 ± 0.111), CYTC (2.461 ± 0.179), ATP5B (1.956 ± 0.161), and ATP5G1 (2.055 ± 0.052) were significantly higher than those of control group(1.000 ± 0.153, 1.000 ± 0.069, 1.000 ± 0.030, 1.000 ± 0.091, 1.000 ± 0.237, t = 4.696, 4.985, 11.540, 7.436, 6.021, P < 0.05). Conclusion When continuously exposed to an environmentally relevant level of inorganic arsenic, the glucose metabolic pattern of HaCaT cells is changed along with lower oxygen consumption and higher glycolysis levels. Key words: Arsenic poisoning; Energy metabolism; Glycolysis; Keratinocytes