Figure 3: PERK deletion in cancer cells provokes ICD-driven anti-tumor immunity.

(A-B) ER Tracker Green (A) and CRANAD-labeled protein aggregates (B) by flow cytometry (MFI ± SEM) in CD45⁻ cells from Scramble and PERK^KO B16 tumors from mice. n=9/group.

(C-D) ATP (C) and HMGB1 (D) (mean ± SEM) in supernatants from resected Scramble or PERK^KO B16 tumors cultured for 24 hours. n=8-12/group (C); n=6-8/group (D).

(E) ExoCRT (MFI ± SEM) in CD45⁻ cells from freshly isolated Scramble or PERK^KO B16 tumors. n=12/group.

(F) Relative expression of Ifnb1, Isg15 and Ifit3 mRNA ± SEM in bulk wildtype, Scramble or PERK^KO B16 tumors from mice. n=13-15/group.

(G) Overall survival for Skin Cutaneous Melanoma patients (TCGA, PanCancer Atlas) stratified by the median ICD metagene signature score. Kaplan-Meier curves of overall survival for ICD high (above the median; n = 228) and low (below the median; n = 229). Gene signature calculation by GSVA.

(H) Mice injected with WT SM1 tumors on the left flank for 10 days later, were implanted with WT (Group 1) or PERK^KO (Group 2) SM1 cells on the right flank. Mice were injected with SM1 PERK^KO cells on the left flank, followed by injection 10 days later with WT (Group 3) or PERK^KO (Group 4) SM1 tumors on the right flank. Tumor growth ± SEM. n=10/group.

(I) WT SM1 tumor growth ± SEM in naïve mice or mice that had rejected PERK^KO SM1 tumors. n=10/group.

(J) Volume ± SEM for SM1 (left flank; SM1 WT) and LLC (right flank; LLC WT) tumors in naïve mice and mice that previously rejected PERK^KO SM1 tumors. n=5/group.

Statistics applied by one-way ANOVA (F, I, J), Student’s t-test (A – E), or log-rank test (G). *, p<0.05; **, p<0.01; ***, p < 0.001; ****, p < 0.0001. Please also see Figure S3.