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Wang X, Tian Z, He L, Meng H, Zhu J, Li Y, Wang J, Hua X, Huang H, Huang C. DNMT3a-mediated upregulation of the stress inducible protein sestrin-2 contributes to malignant transformation of human bronchial epithelial cells following nickel exposure. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 271:115954. [PMID: 38232523 DOI: 10.1016/j.ecoenv.2024.115954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 12/07/2023] [Accepted: 01/06/2024] [Indexed: 01/19/2024]
Abstract
BACKGROUND Nickel is a confirmed human lung carcinogen. Nonetheless, the molecular mechanisms driving its carcinogenic impact on lung tissue remain poorly defined. In this study, we assessed SESN2 expression and the signaling pathways responsible for cellular transformation in human bronchial epithelial cells (HBECs) as a result of nickel exposure. METHODS We employed the Western blotting to determine the induction of SESN2 by nickel. To clarify the signaling pathways leading to cellular transformation following nickel exposure, we applied techniques such as gene knockdown, methylation-specific PCR, and chromatin immunoprecipitation. RESULT Exposure to nickel results in the upregulation of SESN2 and the initiation of autophagy in human bronchial epithelial cells (HBECs). This leads to degradation of HUR protein and consequently downregulation of USP28 mRNA, PP2AC protein, β-catenin protein, and diminished VHL transcription, culminating in the accumulation of hypoxia-inducible factor-1α (HIF-1α) and the malignant transformation of these cells. Mechanistic studies revealed that the increased expression of SESN2 is attributed to the demethylation of the SESN2 promoter induced by nickel, a process facilitated by decreased DNA methyl-transferase 3 A (DNMT3a) expression, while The downregulation of VHL transcription is linked to the suppression of the PP2A-C/GSK3β/β-Catenin/C-Myc pathway. Additionally, we discovered that SESN2-mediated autophagy triggers the degradation of HUR protein, which subsequently reduces the stability of USP28 mRNA and inhibits the PP2A-C/GSK3β/β-Catenin pathway and c-Myc transcription in HBECs post nickel exposure. CONCLUSION Our results reveal that nickel exposure leads to the downregulation of DNMT3a, resulting in the hypomethylation of the SESN2 promoter and its protein induction. This triggers autophagy-dependent suppression of the HUR/USP28/PP2A/β-Catenin/c-Myc pathway, subsequently leading to reduced VHL transcription, accumulation of HIF-1α protein, and the malignant transformation of human bronchial epithelial cells (HBECs). Our research offers novel insights into the molecular mechanisms that underlie the lung carcinogenic effects of nickel exposure. Specifically, nickel induces aberrant DNA methylation in the SESN2 promoter region through the decrease of DNMT3a levels, which ultimately leads to HIF-1α protein accumulation and the malignant transformation of HBECs. Specifically, nickel initiates DNA-methylation of the SESN2 promoter region by decreasing DNMT3a, ultimately resulting in HIF-1α protein accumulation and malignant transformation of HBECs. This study highlights DNMT3a as a potential prognostic biomarker or therapeutic target to improve clinical outcomes in lung cancer patients.
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Affiliation(s)
- Xinxing Wang
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory, Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China; Tianjin Institute of Environmental and Operational Medicine, Tianjin 300050, China
| | - Zhongxian Tian
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory, Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Lijiong He
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory, Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Hao Meng
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory, Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Junlan Zhu
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory, Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Yang Li
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory, Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Jingjing Wang
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory, Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Xiaohui Hua
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory, Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Haishan Huang
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory, Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Chuanshu Huang
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory, Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China.
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Fu X, Murakami M, Hashimoto O, Matsui T, Funaba M. Regulatory mechanisms underlying interleukin-6 expression in murine brown adipocytes. Cell Biochem Funct 2024; 42:e3915. [PMID: 38269513 DOI: 10.1002/cbf.3915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 12/16/2023] [Accepted: 12/20/2023] [Indexed: 01/26/2024]
Abstract
Three types of adipocytes, white, brown, and beige, regulate the systemic energy balance through the storage and expenditure of chemical energy. In addition, adipocytes produce various bioactive molecules known as adipokines. In contrast to white adipocyte-derived molecules, less information is available on the adipokines produced by brown adipocytes (batokine). This study explored the regulatory expression of interleukin (IL)-6 in cell culture studies. Norepinephrine or a nonselective β-adrenergic receptor agonist increased the expression of IL-6 in primary brown adipocytes and HB2 brown adipocytes. Treatment with forskolin (Fsk), an activator of the cAMP-dependent protein kinase (PKA) pathway (downstream signaling of the β-adrenergic receptor), efficiently stimulated IL-6 expression in brown adipocytes and myotubes. Phosphorylated CREB and phosphorylated p38 MAP kinase levels were increased in Fsk-treated brown adipocytes within 5 min. In contrast, a long-term (∼60 min and ∼4 h) treatment with Fsk was required for increase in STAT3 phosphorylation and C/EBPβ expression, respectively. The PKA, p38 MAP kinase, STAT3, and C/EBPβ pathways are required for the maximal IL-6 expression induced by Fsk, which were verified by use of various inhibitors of these signal pathways. Vitamin C enhanced Fsk-induced IL-6 expression through the extracellular signal-regulated kinase activity. The present study provides basic information on the regulatory expression of IL-6 in activated brown adipocytes.
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Affiliation(s)
- Xiajie Fu
- Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Masaru Murakami
- Laboratory of Molecular Biology, Azabu University School of Veterinary Medicine, Sagamihara, Japan
| | - Osamu Hashimoto
- Department of Veterinary Medicine, College of Bioresource Science, Nihon University, Fujisawa, Japan
| | - Tohru Matsui
- Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Masayuki Funaba
- Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
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