Benzo[a]pyrene-induced up-regulation of circ_0003552 via ALKBH5-mediated mA modification promotes DNA damage in human bronchial epithelial cells.

Benzo [a]pyrene (B [a]P) is a widespread environmental chemical pollutant that has been linked to the development of various diseases. However, the specific mechanism of action remains unclear. In this study, human bronchial epithelial 16HBE and BEAS-2B cells were exposed to B [a]P at 0-32 μM to assess the DNA-damaging effects. B [a]P exposure resulted in elevated expression of γ-H2AX, a marker of DNA damage. The mA RNA methylation assay showed that B [a]P exposure increased the extent of mA modification and the demethylase ALKBH5 played an integral role in this process. Moreover, the results of the comet assay and Western blot analysis showed an increase in mA modification mediated by ALKBH5 that promoted DNA damage. Furthermore, the participation of a novel circular RNA, circ_0003552, was assessed by high-throughput sequencing under the condition of high mA modification induced by B [a]P exposure. In subsequent functional studies, an interference/overexpression system was created to confirm that circ_0003552 participated in regulation of DNA damage. Mechanistically, circ_0003552 had an mA binding site that could regulate its generation. This study is the first to report that B [a]P upregulated circ_0003552 through mA modification, thereby promoting DNA damage. These findings revealed that epigenetics played a key role in environmental carcinogen-induced DNA damage, and the quantitative changes it brought might provide an early biomarker for future medical studies of genetic-related diseases and a new platform for investigations of the interaction between epigenetics and genetics.