4-氨基聯苯已被認定為人類致癌物質，且廣泛存在於日常生活中。先前的研究中證實，4-氨基聯苯會造成ROS的上升及誘導調控DNA修復蛋白的miRNA生成，但對於兩者在4-氨基聯苯對於人類肝癌細胞的毒理機制中扮演的角色仍所知甚少。研究中利用生物資訊軟體TargetScan預測，得知DNA雙股斷裂修復蛋白MCM8會受miRNA-630調控，再藉由觀察-H2AX的表現量偵測DNA雙股斷裂程度。經實驗證實miRNA-630會抑制MCM8的生成，並確實會導致同源重組修復效率下降，抑制DNA雙股斷裂修復。同時也在合併處理4-氨基聯苯與NAC(N-acetyl-1-cysteine)的細胞中，發現miR-630的生成及DNA損傷程度皆有降低，故得知ROS會誘導miRNA-630且參與DNA雙股斷裂修復的調控。 以上結果證實，經4-氨基聯苯處理後細胞會產生ROS，然後誘導miRNA-630表現，導致DNA修復蛋白MCM8表現量被抑制，最終造成的DNA損傷。 ;4-ABP (4-Aminobiphenyl) is recognize as a human carcinogen, and commonly found in our daily life. Previous studies have shown that 4-ABP causes oxidative DNA damage and induces expression of some miRNAs involved in the regulation of DNA repair. However, the mechanism about the role of miRNAs involved in oxidative DNA damage in 4-ABP-treated hepatoma cells is unclear. By using TargetScan software, we found that miR-630 is a conserved target of MCM8, a DNA double-strand breaks repair protein. Therefore, we want to figure out the effects of miRNA on MCM8 expression. Our results proved that the elevated expression of miR-630 resulted in the decrease of MCM8 expression, causing the significant decrease of homologous recombination activity. Accordingly, the repair of DNA double-strand breaks (DSBs) was attenuated as evidenced from γ-H2AX analysis. In 4-ABP-treated cells, we found that the levels of miR-630 expression and DNA damage were attenuated by co-treatment with N-acetyl-1-cysteine (NAC), indicating that ROS-dependent miR-630 was involved in DSBs repair. Collectively, 4-ABP induces ROS (Reactive oxygen species) generate, increases miRNA-630 expression, and then attenuates repair of DNA double-strand breaks by targeting MCM8.
