Fig. 7: PERK inhibitor GSK2606414 decreased UPR activation and partially abolished chemosensitizing effect of siKRT8 but did not reverse the blockage of autophagy flux in vitro.

Chordoma cell line CM319 and UCH1 were transfected with siKRT8 followed by treatment of doxorubicin (0.5 μM), irinotecan (50 μM), and GSK2606414 (2 μM) for 24 h. a Western blotting analysis and quantification of p-PERK, p-eIF2α, Cleaved PARP, SQSTM1, and LC3B protein expression (p-PERK and p-eIF2α were normalized to PERK and eIF2α expression, respectively; Cleaved PARP, LC3B, and SQSTM1 were normalized to GAPDH expression; quantification data of p-PERK, p-eIF2α, Cleaved PARP, SQSTM1, and LC3B in “si + Doxo 24 h” group and “si + Irino 24 h” group were derived from the same data set in Figs. 4b and 5b). b Apoptosis of chordoma cells was determined by Annexin V-PE/PI staining measured by flow cytometry (quantification data of apoptosis in “si + Doxo 24 h” group and “si + Irino 24 h” group were derived from the same data set in Fig. 4d) (n = 3, *p < 0.05 vs. the indicated group, **p < 0.01 vs. the indicated group, NS: not statistically significant vs. indicated group, Con: control group, Doxo: doxorubicin-treated group, Irino: irinotecan-treated group. For all the above-mentioned statistical analyses, significance was determined by one-way ANOVA followed by Tukey’s multiple comparisons test and the results were shown as mean ± SD).