Fig. 1
Lactate and lactylation levels were increased, and DNA repair was hyperactivated in EPI-resistant tumor tissues and cells. a Metabolic analysis of energy metabolites in primary tumors from patients with nonresistant NMIBC (NR-PT, n = 4), primary tumors from patients with resistant NMIBC (R-PT, n = 4), and recurrent tumors from patients with resistant NMIBC (R-RT, n = 4), highlighting the glycolytic metabolite lactate; NMIBC represents nonmuscle-invasive bladder cancer. b Lactate concentrations in NR-PT, R-PT, and R-RT bladder tumor samples from patients with nonresistant NMIBC (n = 145) and patients with resistant NMIBC (n = 64) compared via one-way ANOVA followed by Tukey’s test. c Lactate levels were compared via paired two-tailed Student’s t tests. d Representative pan-Kla immunohistochemical staining of NR-PT, R-PT, and R-RT bladder tumor tissues; scale bar: 100 μm. e, f The integral optical densities of pan-Kla staining in NR-PT (n = 145), R-PT (n = 64), and R-RT (n = 64) bladder tumor tissues were compared via one-way ANOVA followed by Tukey’s test and paired two-tailed Student’s t test. Kaplan‒Meier survival curves of the recurrence-free survival (RFS) of patients with NMIBC based on lactate concentrations (g) and pan-Kla levels (h) in primary tumor tissues; the median lactate concentration and the median integral optical density of pan-Kla were employed as the cutoff values; the statistical significance of RFS was determined via the Kaplan‒Meier method, and the P value was calculated via the log-rank test. i Receiver operating characteristic (ROC) analysis for recurrence prediction based on lactate concentrations and pan-Kla levels in primary bladder tumor tissues; red circles indicate cutoff values of 34.69 and 40. j The parental and EPI-resistant (E-resistant) UM-UC-3 cell lines either treated with 0.2 μM epirubicin (EPI) for 24 h or untreated; representative confocal microscopy images (left) and quantitative analyses (right) show the formation and disappearance of γH2AX (green) foci and the merging with DAPI staining (blue) of nuclei; scale bar: 10 μm. k Western blot analysis examining RAD51 accumulation in chromatin fractions and γH2AX expression in whole-cell extracts of parental and E-resistant UM-UC-3 cells before or 24 h after treatment with 0.2 μM EPI. l Heatmap showing energy metabolism metabolites in tumor cells from EPI-treated CDXE-resistant and CDXparental models (n = 3). m Western blot analysis of LDHA and pan-Kla in whole-cell extracts from CDXE-resistant and CDXparental models. n Western blot showing RAD51 chromatin accumulation and γH2AX expression in whole-cell extracts from CDXE-resistant and CDXparental models. ***p < 0.001 represents a significant difference between two groups
