Fig 2: MEK inhibitors and proteasome inhibitors synergistically inhibited tumor progression in vivo(A) Clonogenic assays of 4T1 cells treated with different concentrations of AZD6244 or MG132 for 10–14 days.(B) The relative synergy of different concentrations of drug combinations (expressed as log10 of CI value) in 4T1 cells.(C) 4T1 cells were treated with or without MG132 (2 μM) for 24 h and the related proteins were detected by western blot. Loading control, β-actin.(D) 4T1 cells were treated with or without MG132 (2 μM) for 24 h and the autophagy-related proteins were detected by western blot. Loading control, β-actin.(E) 4T1 cells were treated with different concentrations of rapamycin for 24 h, and then PDPK1 and autophagy-related proteins were detected by western blot. Loading control, β-actin.(F) After treatment with or without MG132 (2 μM) for 24 h, 4T1 cells were treated with CQ (40 μM) for 8 or 12 h, then PDPK1 and autophagy-related proteins were detected by western blot. Loading control, β-actin.(G) BALB/c mice were subcutaneously inoculated with 4 × 105 4T1 cells on day 0. Tumor-bearing mice (n = 8 mice) were treated with various drugs when tumor volume achieved ≈100 mm3. Details of treatment are provided in the STAR Methods.(H) The average tumor growth curves for mice treated with PBS (control), AZD6244, MG132, and AZD6244 plus MG132. The quantitative results are presented as the mean ± SD (n = 8 mice); ∗p < 0.05; one-way ANOVA.(I) Tumors were weighed after the animals were euthanized on day 24. The quantitative results are presented as the mean ± SD (n = 8 mice); ∗∗∗∗p < 0.0001; one-way ANOVA.(J) Degradation of PDPK1 and activation of autophagy were visualized by PDPK1 and LC3 IHC staining. The scale bar represents 100 μm.(K) The results of IHC staining were quantified by Image Pro Plus. The quantitative results are presented as the mean ± SD (n = 4 fields); ∗∗p < 0.01, ∗∗∗∗p < 0.0001; one-way ANOVA.

Fig 3: PSMG2 knockdown activated autophagy in TNBC cells(A and B) After vector (pLKO.1) or PSMG2 shRNA (shPSMG2) transfection, BT549 and MB468 cells were treated with or without AZD6244 (1 µM) for 24 h, and the relative mRNA or ribosome-bound mRNA expression level of PDPK1 was detected by qRT-PCR. Error bars represent the mean ± SD, n = 3 technical replicates.(C) After vector (pLKO.1) or PSMG2 shRNA (shPSMG2) transfection, the autophagy-related proteins were detected by western blot in BT549 and MB468 cells. Loading control, ß-actin.(D and E) BT549 and MB468 cells were treated with or without MG132 (2 µM) for 24 h or bortezomib (100 nM) for 36 h, and then the autophagy-related proteins were detected by western blot. Loading control, ß-actin.(F) BT549 cells, transfected with vector (pLKO.1) or PSMG2 shRNA (shPSMG2), were imaged by transmission electron microscopy. Two magnified views of the electron photomicrograph show a characteristic autophagosome. N, nucleus; ER, endoplasmic reticulum; M, mitochondria; A, autophagosome. The scale bar represents 2 µm and 1 µm, respectively.(G) After PSMG2 knockdown, ER stress-related proteins were detected by western blot in BT549 and MB468 cells. Loading control, ß-actin.

Fig 4: miR-1178-3p-mediated PDPK1 regulated angiogenesis of CMECs and proliferation and migration of VSMCs.a, b Expression of PDPK1 was detected by qRT–PCR and western blotting by overexpressing or suppressing of PDPK1 in CMECs, respectively, GAPDH served as a control; cc Tube formation analysis was used to detect capillary-like structures in the PDPK1 overexpression or suppression group and rescued by miR-1178-3p; Bar = 200 µm; d CCK-8 assay was used to detect the viability of VSMCs in the PDPK1 overexpression or suppression of group and rescued by miR-1178-3p at 24 h, 48 h and 72 h; E Flow cytometry was used to detect the cell cycle of VSMCs in the PDPK1 overexpression or suppression group and rescued by miR-1178-3p; f Migration of VSMCs was detected by Transwell assay when PDPK1 overexpressed or suppressed and rescued by miR-1178-3p, Bar = 200 µm. Data are mean ± SD. **P < 0.01, Over-PDPK1 group vs. NC group; ##P < 0.01, Sh-PDPK1 group vs. NC group.

Fig 5: PSMG2 knockdown downregulated PDPK1/AKT signaling(A) The scatterplot shows the correlation between proteasome and all 50 hallmark gene sets in the two single-cell transcriptome datasets (GEO: GSE75688 and GEO: GSE11838). The x axis and y axis represent the correlation coefficients of proteasome and hallmark gene sets in the GEO: GSE11838 and GEO: GSE75688 datasets, respectively. The size and color of the points represent the −log10 p value in the GEO: GSE11838 and GEO: GSE75688 datasets, respectively. The points of the top 5 signal pathways in the comprehensive correlation are marked with different colored outer circles.(B) The scatterplot shows the high correlation between mTOR signaling and proteasome in two independent single-cell transcriptomic datasets (GEO: GSE75688 and GEO: GSE11838). The pink triangles represent the GEO: GSE75688 dataset, and the blue dots represent the GEO: GSE11838 dataset.(C) After vector (pLKO.1) or PSMG2 shRNA (shPSMG2) transfection, BT549 and MB468 cells were treated with AZD6244 (1 μM) for 2 or 24 h, and then the phosphorylation of ERK in the MAPK pathway and the phosphorylation and total protein of AKT and PDPK1 in the upstream mTOR pathway were detected by western blot. Loading control, β-actin.(D) BT549 and MB468 cells were treated with or without MG132 (2 μM) for 24 h and the related proteins were detected by western blot. Loading control, β-actin.(E) After transfection with vector (pLKO.1) or PDPK1 shRNA (shPDPK1), BT549 and MB468 cells were treated with AZD6244 (1 μM) for 2 or 24 h, and then the phosphorylation of ERK and AKT and total protein levels of PDPK1 were detected by western blot. Loading control, β-actin.(F) Clonogenic assays of PDPK1-knockdown cells (BT549 and MB468) treated with or without AZD6244 (1 μM) for 10–14 days.(G) The results of the clonogenic assays (F) were quantified by ImageJ. The quantitative results are presented as the mean ± SD (n = 4 technical replicates); ∗∗∗p < 0.001; one-way ANOVA.(H) After vector (pLKO.1) or PSMG2 shRNA (shPSMG2) transfection, BT549 and MB468 cells were transfected with vector (cPPT) or the overexpression vector for PDPK1 (PDPK1), then the phosphorylation of PDPK1 and AKT was analyzed by western blot. Loading control, β-actin.(I) Under PSMG2 shRNA (shPSMG2) transfection, BT549 and MB468 cells were transfected with vector (cPPT) or the vector for PDPK1 expression (cPPT-PDPK1) and treated with or without AZD6244 (0.1 or 0.5 μM) for 10–14 days.(J and K) The results of the clonogenic assays (I) were quantified by ImageJ. The quantitative results are presented as the mean ± SD (n = 4 technical replicates); ∗p < 0.01, ∗∗∗∗p < 0.0001; one-way ANOVA.