Key Laboratory of Agrometeorology of Jiangsu Province, Department of Ecology, School of Applied Meteorology, Nanjing University of Information Science & Technology (NUIST), Nanjing, 210044, PR China.
Department of Environmental Health Sciences, Morrill I, N344, University of Massachusetts, Amherst, MA, 01003, USA.
Environ Res. 2021 Aug;199:111395. doi: 10.1016/j.envres.2021.111395. Epub 2021 May 25.
Formaldehyde (FA) is a naturally-occurring compound, produced endogenously in diverse living organisms. It also occurs widely in the environment due to anthropogenic (e.g. used as a chemical intermediate) and natural sources (e.g. a component of the volatile organic compounds blends emitted by plants). While FA is considered a potential carcinogen, living organisms have the ability to cope with FA, and some minimum endogenous levels of FA may be required for health. Recently, genetic engineering approaches transferring biological information from one organism to another led to increased assimilation of and conferred genetic-based tolerance to FA in plants-microorganisms systems. Here, we propose that FA commonly induces hormesis, a hypothesis that we confirm by collating evidence from various published studies with animals, plants, and microorganisms. The stimulation by low doses below the no-observed-adverse-effect-level (NOAEL) was modest in magnitude, in agreement with the general hormesis literature. In plants, among the endpoints showing hormesis were growth, lipid peroxidation, and photosynthetic pigments. In various animal cells, hormesis was observed in cell proliferation and viability, responses that were related to mechanisms, such as activation of phosphorylated ERK (extra-cellular signaling-regulated kinase) expression, acceleration of the process of cell division, and enhancement of the Warburg effect (i.e. use of glycolysis by tumor cells to produce energy for rapid growth). Hormetic in vitro responses were reported in several cancerous/tumorous cell lines, suggesting that FA has the potential to influence tumor promotion within a specific concentration range and biological context. These observations suggest that FA commonly acts in an hormetic manner with implications for study designs across a broad range of biological models and in the assessment of environmental and human risks associated with FA exposures.
甲醛（FA）是一种天然存在的化合物，在各种生物体中内源性产生。由于人为因素（例如用作化学中间体）和自然来源（例如植物挥发有机化合物混合物的一个组成部分），它也广泛存在于环境中。虽然 FA 被认为是一种潜在的致癌物质，但生物体有能力应对 FA，并且可能需要一些最低限度的内源性 FA 水平才能保持健康。最近，将生物信息从一种生物体转移到另一种生物体的基因工程方法导致植物-微生物系统中 FA 的同化和遗传基础上的耐受性增加。在这里，我们提出 FA 通常会诱导适应现象，这一假设我们通过整理来自不同动物、植物和微生物的已发表研究的证据来证实。在低于无观察到不良效应水平（NOAEL）的低剂量下，刺激作用的幅度适中，这与适应现象的一般文献一致。在植物中，表现出适应现象的终点包括生长、脂质过氧化和光合色素。在各种动物细胞中，细胞增殖和活力表现出适应现象，这些反应与机制有关，例如磷酸化 ERK（细胞外信号调节激酶）表达的激活、细胞分裂过程的加速以及沃伯格效应（即肿瘤细胞利用糖酵解产生能量以快速生长）的增强。在几种癌/肿瘤细胞系中报告了体外适应反应，这表明 FA 有可能在特定浓度范围和生物背景下影响肿瘤促进。这些观察结果表明，FA 通常以适应现象的方式发挥作用，这对广泛的生物学模型中的研究设计以及与 FA 暴露相关的环境和人类风险评估具有影响。
