{Reference Type}: Journal Article {Title}: YZL-51N functions as a selective inhibitor of SIRT7 by NAD+ competition to impede DNA damage repair. {Author}: Kang TS;Yan YM;Tian Y;Zhang J;Zhang M;Shu Y;Huang J;He J;Tao CT;Zhu Q;Gu J;Lu X;Cheng YX;Zhu WG; {Journal}: iScience {Volume}: 27 {Issue}: 6 {Year}: 2024 Jun 21 {Factor}: 6.107 {DOI}: 10.1016/j.isci.2024.110014 {Abstract}: The NAD+-dependent deacetylase SIRT7 is a pivotal regulator of DNA damage response (DDR) and a promising drug target for developing cancer therapeutics. However, limited progress has been made in SIRT7 modulator discovery. Here, we applied peptide-based deacetylase platforms for SIRT7 enzymatic evaluation and successfully identified a potent SIRT7 inhibitor YZL-51N. We initially isolated bioactive YZL-51N from cockroach (Periplaneta americana) extracts and then developed the de novo synthesis of this compound. Further investigation revealed that YZL-51N impaired SIRT7 enzymatic activities through occupation of the NAD+ binding pocket. YZL-51N attenuated DNA damage repair induced by ionizing radiation (IR) in colorectal cancer cells and exhibited a synergistic anticancer effect when used in combination with etoposide. Overall, our study not only identified YZL-51N as a selective SIRT7 inhibitor from insect resources, but also confirmed its potential use in combined chemo-radiotherapy by interfering in the DNA damage repair process.