ESR1 and breast cancer: Employing the widely recognized marker for oxidative DNA stress, 8-oxo-guanine (8-oxoG), which is a downstream product of phosphorylated 8-oxo-dGDP, we observed a substantial increase in nuclear 8-oxoG levels after NUDT5 knockdown in TNBC cell lines (MDA-MB-231, MDA-MB-436 and MDA-MB-468) compared to ER-positive breast cancer cell lines (MDA-MB-231 and MCF7 in Fig. 5A; MDA-MB-436, MDA-MB-468, ZR-75-1 and MDA-MB-361 in Additional file 7: Figure S7A, S7B).