黑碳及其复合物通过DNA甲基化改变促进细胞恶性增殖的机理研究

Black carbon is one of the major components of atmospheric fine particulate matter. Because of its particular structural characteristics, black carbon can absorb toxic pollutants to form the composites of black carbon and pollutants (black carbon-pollutants). Black carbon has become the primary dangerous factor in environment and health. It is an important scientific problem to investigating the health effects and toxicological mechanism of black carbon-pollutants. It has been shown that atmospheric fine particulate matter could promote cell malignant proliferation. However, the role of black carbon exposure in cell malignant proliferation is unclear. We previously found that low dose exposure of black carbon could promote lung cancer cell proliferation. It has been also demonstrated that black carbon could increase the levels of DNA methylation. Whereas it is still lack of systematic research for the effects and molecular mechanisms underlying black carbon and black carbon-pollutants promote cell malignant proliferation through altering DNA methylation. Accordingly, our program will produce black carbon and black carbon-polycyclic aromatic hydrocarbons (PAHs) to investigate the effects and mechanisms of black carbon and composites on malignant proliferation in normal and tumor cells. Furthermore, this study will demonstrate the molecular mechanism of black carbon and black carbon-PAHs composite-caused cell malignant proliferation by the change of DNA methylation. This study will provide a scientific basis for the effective evaluation of the health hazards and toxic mechanisms of atmospheric fine particulate matter.

黑碳是大气细颗粒物的重要组分，极易吸附有毒污染物而形成黑碳-污染物复合物，已成为当前主要的环境健康危险因素之一。探讨黑碳及其复合物的健康效应和毒理学机制，是环境健康领域亟待解决的重要科学问题。研究显示，大气细颗粒物能够促进细胞的恶性增殖。然而，黑碳暴露对细胞恶性增殖的作用仍不明确。项目组研究显示，黑碳低剂量暴露能够促进肺癌细胞的恶性增殖。我们的前期工作还发现，黑碳暴露可增加基因组DNA甲基化的水平。但对于黑碳及其复合物是否通过DNA甲基化改变促进细胞恶性增殖的效应及分子机制，尚缺乏系统的研究。因此，本项目拟以制备的黑碳和黑碳-多环芳烃复合物为研究模型，探讨黑碳及其复合物对正常及肿瘤细胞恶性增殖的影响和作用机制，并从表观遗传学角度深入揭示黑碳及黑碳-多环芳烃复合物通过诱导DNA甲基化改变促进细胞恶性增殖的分子机理。该项目的研究将为有效评价大气细颗粒物毒性组分的健康危害和毒性机制提供科学依据。

项目组研究显示，黑碳低剂量暴露能够促进肺癌细胞的恶性增殖，增加基因组DNA甲基化的水平。但对于黑碳及污染物复合暴露是否通过DNA甲基化改变促进细胞恶性增殖的效应及分子机制，尚缺乏系统的研究。黑碳的表征显示C824455，Printex U、SA4B结构稳定，具有更好的分散性和生物兼容性。C824455，Printex U和SA4B体内暴露后引起了小鼠肺组织损伤、充血，且Printex U和SA4B增强了小鼠肺组织DNA甲基化水平。Printex U和SA4B在低浓度暴露下促进了A549细胞和BEAS细胞的增殖，且Printex U还促进了A549细胞的迁移和侵袭。在促增殖浓度暴露下，Printex U和SA4B增强了A549细胞和BEAS细胞的DNA甲基化水平，改变了DNMT酶和TET酶的蛋白表达水平。分子机制方面，Printex U和SA4B暴露引起了细胞转运和分解代谢相关基因的差异甲基化改变，但具体分子机制仍需深入探索。Printex U和SA4B与多环芳烃Py复合暴露能够促进A549细胞的增殖，导致细胞DNA甲基化水平增加，DNMT1的表达水平升高；而与单独暴露比较，Printex U和SA4B与多环芳烃BaP复合暴露导致促A549细胞增殖作用减弱，细胞5mc水平降低，DNMT1的蛋白水平受到抑制。其中的分子机制有待于进一步深入研究。该项目的研究初步为评价大气细颗粒物毒性组分的健康风险和毒性机制提供了科学依据。