Cadmium induces apoptotic program imbalance and cell cycle inhibitor expression in cultured human astrocytes

• Published in: Environmental toxicology and pharmacology Vol. 65; pp. 53 - 59
• Main Authors: Ospondpant, Dusadee, Phuagkhaopong, Suttinee, Suknuntha, Kran, Sangpairoj, Kant, Kasemsuk, Thitima, Srimaroeng, Chutima, Vivithanaporn, Pornpun
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.01.2019; Elsevier Science Ltd
• Subjects: 1-Phosphatidylinositol 3-kinase; AKT protein; Antioxidants; Apoptosis; Astrocytes; B-cell lymphoma; Bax; Bax protein; Bcl-2; Bcl-2 protein; Cadmium; Calcium; Calcium (intracellular); Catalase; Cell cycle; Cell growth; Cell proliferation; Cytotoxicity; Deoxyribonucleic acid; DNA; DNA fragmentation; Enzymes; Epithelial cells; Fibroblasts; Gene expression; Glutathione; Heavy metals; Inhibitors; Lungs; Lymphocytes B; Lymphoma; Mitochondria; Neurodegenerative diseases; Neurogenesis; Oxidative stress; p21; p27; p53; Proteins; Toxicity; Bcl-2; Bax; Cadmium; p27; p21; p53
• ISSN: 1382-6689; 1872-7077
• DOI: 10.1016/j.etap.2018.12.001

•Cadmium increased the ratio of pro-apoptotic Bax/anti-apoptotic Bcl-2 expression in human astrocytes.•Cadmium caused S and G2/M phase cell cycle arrest in human astrocytes.•Cadmium upregulated expression of p53 and two cyclin-dependent kinase inhibitors, p21 and p27. Cadmium is a highly neurotoxic heavy metal impairing neurogenesis and induces neurodegenerative disorders. Toxic concentrations of cadmium induce astrocytic apoptosis by depleting intracellular glutathione levels, elevating intracellular calcium levels, altering mitochondria membrane potentials, and activating JNK and PI3K/Akt signaling pathways. Cadmium suppresses cell proliferation in kidney epithelial cells, lung fibroblasts, and primary myelocytes; however, cadmium’s effects on proteins regulating oxidative stress, apoptosis, and cell proliferation in astrocytes are less known. The present study hypothesized that cadmium alters levels of antioxidant enzymes, apoptotic regulator proteins, and cell cycle inhibitor proteins, resulting in apoptosis and cell cycle arrest. Concentrations ≥20 μM cadmium induced apoptosis and led to intracellular changes including DNA fragmentation, reduced mRNA expression of antioxidant enzymes (i.e., catalase and glutathione S transferase-A4), downregulation of B-cell lymphoma 2 (Bcl-2), and upregulation of Bcl-2-associated X protein (Bax). Moreover, cadmium suppressed astrocytic proliferation by inducing S and G2/M phase cell cycle arrest and promoting p53, p21, and p27 expression. In conclusion, this study provides mechanistic insight into cadmium-induced cytotoxicity of astrocytes and highlights potential targets for prevention of cadmium-induced apoptosis and cell cycle arrest.