Fig. 1: HMGCR upregulation following ICB-mediated immune selection promotes ferroptosis resistance.

B16 P0, P3 cells and TC-1 P0, P3 cells were treated with indicated concentrations of RSL3 (a) or Erastin (b) for 24 h. Cell viability was measured by Trypan blue exclusion assay. The concentrations causing 50% inhibition of cell viability (IC₅₀ values) were determined. c, d B16 P0, P3 cells and TC-1 P0, P3 cells were treated with RSL3 (1 or 2 μM) in the absence or presence of zVAD (10 μM) or Lip-1 (1 μM) for an additional 20 h. The percentage of 7-AAD⁺ cells c and relative lipid ROS d were measured by flow cytometry. The data are representative of those from 3 independent experiments with triplicate. e The real time PCR array analysis for ferroptosis negative regulator genes in B16 P0, P3 and TC-1 P0, P3. f Venn diagram showing the overlap of ferroptosis negative regulator genes between upregulated in B16 P3 versus P0 (red) and those upregulated in TC-1 P3 versus P0 (green). g HMGCR protein levels in B16 P0, B16 P3, TC-1 P0, and TC-1 P3 was determined by Western blot. β-actin was included as an internal loading control. h The HMG-CoA reductase activity in B16 P0, B16 P3, TC-1 P0, and TC-1 P3 (n = 3; in duplicate). Flow cytometry analysis of the 7AAD⁺ cells (i) and relative lipid ROS (j) in indicated cells treated with RSL3 with or without Lip-1 (1 μM) for 20 h. All data are representative of those from 3 independent experiments with triplicate. The error bars represent mean ± SD. All p value are presented exactly in figure. The p values by two-way ANOVA (c, d, i, j), and unpaired, two-tailed Student’s t test (e, g, h) are indicated. Source data are provided as a Source data file.