Department of Obstetrics and Gynecology, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Hasama-machi, Yufu, Oita, 879-5593, Japan.
Department of Pharmacology, Faculty of Medicine, Oita University, Yufu, Japan.
Sci Rep. 2021 Apr 8;11(1):7718. doi: 10.1038/s41598-021-87344-2.
DNA replication inhibitors are utilized extensively in studies of molecular biology and as chemotherapy agents in clinical settings. The inhibition of DNA replication often triggers double-stranded DNA breaks (DSBs) at stalled DNA replication sites, resulting in cytotoxicity. In East Asia, some traditional medicines are administered as anticancer drugs, although the mechanisms underlying their pharmacological effects are not entirely understood. In this study, we screened Japanese herbal medicines and identified two benzylisoquinoline alkaloids (BIAs), berberine and coptisine. These alkaloids mildly induced DSBs, and this effect was dependent on the function of topoisomerase I (Topo I) and MUS81-EME1 structure-specific endonuclease. Biochemical analysis revealed that the action of BIAs involves inhibiting the catalytic activity of Topo I rather than inducing the accumulation of the Topo I-DNA complex, which is different from the action of camptothecin (CPT). Furthermore, the results showed that BIAs can act as inhibitors of Topo I, even against CPT-resistant mutants, and that the action of these BIAs was independent of CPT. These results suggest that using a combination of BIAs and CPT might increase their efficiency in eliminating cancer cells.
DNA 复制抑制剂在分子生物学研究中被广泛应用，并在临床环境中作为化疗药物。DNA 复制的抑制常常在停滞的 DNA 复制位点引发双链 DNA 断裂（DSB），导致细胞毒性。在东亚，一些传统药物被用作抗癌药物，尽管其药理作用的机制尚不完全清楚。在这项研究中，我们筛选了日本草药，并鉴定出两种苯并异喹啉生物碱（BIAs），小檗碱和黄连碱。这些生物碱轻度诱导 DSB，这种作用依赖于拓扑异构酶 I（Topo I）和 MUS81-EME1 结构特异性内切酶的功能。生化分析表明，BIAs 的作用涉及抑制拓扑异构酶 I 的催化活性，而不是诱导拓扑异构酶 I-DNA 复合物的积累，这与喜树碱（CPT）的作用不同。此外，结果表明 BIAs 可以作为拓扑异构酶 I 的抑制剂，即使针对 CPT 耐药突变体也是如此，并且这些 BIAs 的作用独立于 CPT。这些结果表明，使用 BIAs 和 CPT 的组合可能会提高它们消除癌细胞的效率。
