With rapid development of novel nanotechnologies that incorporate engineered nanomaterials (ENMs) into manufactured products, long-term, low dose ENM exposures in occupational settings is forecasted to occur with potential adverse outcomes to human health. Few ENM human health risk assessment efforts have evaluated tumorigenic potential of ENMs. Two widely used nano-scaled metal oxides (NMOs), cerium oxide (nCeO2) and ferric oxide (nFe2O3) were screened in the current study using a sub-chronic exposure to human primary small airway epithelial cells (pSAECs). Multi-walled carbon nanotubes (MWCNT), a known ENM tumor promoter, was used as a positive control. Advanced dosimetry modeling was employed to ascertain delivered vs. administered dose in all experimental conditions. Cells were continuously exposed in vitro to deposited doses of 0.18 μg/cm2 or 0.06 μg/cm2 of each NMO or MWCNT, respectively, over 6 and 10 weeks, while saline- and dispersant-only exposed cells served as passage controls. Cells were evaluated for changes in several cancer hallmarks, as evidence for neoplastic transformation. At 10 weeks, nFe2O3- and MWCNT-exposed cells displayed a neoplastic-like transformation phenotype with significant increased proliferation, invasion and soft agar colony formation ability compared to controls. nCeO2-exposed cells showed increased proliferative capacity only. Isolated nFe2O3 and MWCNT clones from soft agar colonies retained their respective neoplastic-like phenotypes. Interestingly, nFe2O3-exposed cells, but not MWCNT cells, exhibited immortalization and retention of the neoplastic phenotype after repeated passaging (12 - 30 passages) and after cryofreeze and thawing. High content screening and protein expression analyses in acute exposure ENM studies vs. immortalized nFe2O3 cells, and isolated ENM clones, suggested that long-term exposure to the tested ENMs resulted in iron homeostasis disruption, an increased labile ferrous iron pool, and subsequent reactive oxygen species generation, a well-established tumorigenesis promotor. In conclusion, sub-chronic exposure to human pSAECs with a cancer hallmark screening battery identified nFe2O3 as possessing neoplastic-like transformation ability, thus suggesting that further tumorigenic assessment is needed.

中文翻译：

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通过人类细胞体外筛选模型评估 CeO 2 和 Fe 2 O 3 工程纳米粒子的致瘤潜力

随着将工程纳米材料 (ENM) 纳入制成品的新型纳米技术的快速发展，预计职业环境中的长期、低剂量 ENM 暴露将对人类健康产生潜在的不利后果。很少有 ENM 人类健康风险评估工作评估了 ENM 的致瘤潜力。在当前的研究中使用亚慢性暴露于人类原代小气道上皮细胞 (pSAECs) 筛选了两种广泛使用的纳米级金属氧化物 (NMO)，氧化铈 (nCeO2) 和氧化铁 (nFe2O3)。多壁碳纳米管 (MWCNT)，一种已知的 ENM 肿瘤促进剂，用作阳性对照。采用先进的剂量学模型来确定所有实验条件下的给药剂量与给药剂量。细胞在体外连续暴露于 0 的沉积剂量。在 6 周和 10 周内，每种 NMO 或 MWCNT 分别为 18 μg/cm2 或 0.06 μg/cm2，而仅暴露于盐水和分散剂的细胞作为传代对照。评估细胞的几种癌症标志的变化，作为肿瘤转化的证据。在 10 周时，暴露于 nFe2O3 和 MWCNT 的细胞显示出类似肿瘤的转化表型，与对照相比，增殖、侵袭和软琼脂集落形成能力显着增加。nCeO2 暴露的细胞仅显示增殖能力增加。从软琼脂菌落中分离出的 nFe2O3 和 MWCNT 克隆保留了它们各自的肿瘤样表型。有趣的是，暴露于 nFe2O3 的细胞，而不是 MWCNT 细胞，在重复传代（12-30 次传代）和冷冻和解冻后表现出永生化和肿瘤表型的保留。急性暴露 ENM 研究与永生化 nFe2O3 细胞和分离的 ENM 克隆中的高内涵筛选和蛋白质表达分析表明，长期暴露于测试的 ENM 会导致铁稳态破坏、不稳定的亚铁池增加和随后的活性氧物种生成，一种成熟的肿瘤发生促进剂。总之，亚慢性暴露于具有癌症标志筛选组合的人类 pSAEC 将 nFe2O3 鉴定为具有肿瘤样转化能力，因此表明需要进一步的致瘤性评估。不稳定的亚铁池增加，随后产生活性氧，这是一种公认​​的肿瘤发生促进剂。总之，亚慢性暴露于具有癌症标志筛选组合的人类 pSAEC 确定 nFe2O3 具有肿瘤样转化能力，因此表明需要进一步的致瘤性评估。不稳定的亚铁池增加，随后产生活性氧，这是一种公认​​的肿瘤发生促进剂。总之，亚慢性暴露于具有癌症标志筛选组合的人类 pSAEC 确定 nFe2O3 具有肿瘤样转化能力，因此表明需要进一步的致瘤性评估。