Fig. 6: CHAC1 induction by methionine intermittent deprivation sensitizes the tumor against CTL and PD-1 blockade therapy.
a–c Experimental design for co-culture of ovalbumin (OVA+) and nano-luciferase (Luc+) expressing B16F10 and activated OT-I cells (a, left). Control (sgControl) or CHAC1 deficient (sgCHAC1) OVA+Luc+ B16F10 cells were treated with St-Met− for 8 h and then co-cultured with OT-I cells (tumor: T = 1: 8). Luciferase activity from tumor cells was quantified (a, right). Cell death (b) or lipid ROS (c) of tumor cells in the co-culture system was determined. n = 3 biological replicates and P values are determined using two-way ANOVA. d Relative mRNA expression of CHAC1 in B16F10 cells treated with supernatant from activated OT-I cells (CTL) for indicated times. e, f Control (Empty) or CHAC1-Flag over-expressing B16F10 cells were pulsed with OVA257–264 peptide and then co-cultured with OT-I cells for 60 h (e) or 36 h (f). Cell death (e) or lipid ROS level (f) in tumor cells from the co-culture system was quantified. g–j Effect of dietary methionine intermittent deprivation on PD-1 blockade-mediated cancer immunotherapy. Experimental design of B16F10 tumor in C57BL/6 mice (n = 16 or 10 mice per group) (g). Tumor volumes were monitored over time (h, i), and tumor weights were measured at the endpoint ( j). Data were presented as mean ± s.e.m. and P values are determined by two-way ANOVA (h, i) and one-way ANOVA (j). CHAC1 (k) and PTGS2 (l) mRNA levels in isolated tumor tissues were quantified (n = 5 tumors per group). P values are determined by Kruslal–Wallis with Dunn’s multiple comparisons test (k, l). Images of immunohistochemistry for 4HNE in tumor tissue slides were presented; scale bars,100 μm (m). The percentages of CD8+ T cells in CD45+ cells and the percentage of cells expressing IFNγ or TNF in CD8+ and CD4+ T cells were quantified (n). n = 5 tumors per group, and P values are determined by one-way ANOVA (n). Source data are provided as a Source Data file.
