Fig. 4

LSD1 increased ERK2 (MAPK1) expression, and thus maintained LCSCs stemness and further enhanced their radioresistance. A ERK2 (MAPK1) expression in normal samples and liver cancer samples, as analyzed by TCGA database. LIHC, liver hepatocellular carcinoma. Red box plots represent tumor samples, and gray box plots represent normal samples. *p < 0.01 compared with normal samples. B The correlation between ERK2 (MAPK1) expression and overall survival rate of liver cancer patients analyzed by TCGA database. The upper right is the significant p value and legend. C The positive expression of LSD1 and ERK2 (MAPK1) proteins in clinical liver cancer tissue samples, as measured by immunohistochemistry. *p < 0.05 compared with adjacent normal tissues. D The silencing efficiency of ERK2 (MAPK1) shRNAs in Hep3B and Huh7 CSCs, as detected by Western blot, normalized to GAPDH. E Microsphere formation assay was adopted to measure the stemness of LCSCs with ERK2 (MAPK1) silencing. *p < 0.05 compared with shCtl-treated cells. F The colony formation ability of LCSCs with ERK2 (MAPK1) silencing after exposure to 6 Gy X-ray, as measured by clonogenic assay. *p < 0.05 compared with shCtl-treated cells. G Quantitative analysis the relative expression of LSD1 and ERK2 (MAPK1) proteins in Hep3B and Huh7 CSCs in response to shLSD1, oe-ERK2 or in combination by Western blot, relative to GAPDH. H The LCSC stemness after treatment with shLSD1, oe-ERK2 or in combination measured by microsphere formation assay. I, After 6 Gy X-ray treatment, cell proliferation in the presence of shLSD1, oe-ERK2 or in combination, as examined by clonogenic assay. *p < 0.05 compared with shCtl + oe-NC-treated cells. #p < 0.05 compared with shLSD1 + oe-NC-treated cells. Above data were shown as mean ± standard deviation. Results between two groups were compared by unpaired t test. The data comparison between multiple groups was performed by one-way ANOVA with Tukey’s post-hoc test. Cellular experiments were repeated in triplicate