Fig 2: Disturbing the TRIB3/MYC interaction destabilizes MYC and inhibits lymphoma.a The kinetic interaction of CM4 and TRIB3 was determined by surface plasmon resonance (SPR) analyses. b The highest scoring Dock model of the CM4 and TRIB3 complex is shown. Upper: the surface of CM4 (green) and the TRIB3 complex. Below: the 3D structure of CM4 (yellow) and the TRIB3 complex. c The kinetic interaction of the TRIB3 and MYC proteins was determined by SPR analyses with or without CM4. d Structured illumination microscopic (SIM) images of PCON- or PCM4-treated Raji cells (30 min) stained for MYC and TRIB3. Dotted line border square: area processed for 3D surface rendering (insets). e In vitro interaction assays show that the CM4 peptide increased the binding of MYC and UBE3B. f Representative images of MYC and UBE3B foci (left) and quantification of the number of MYC/UBE3B colocalized foci in Raji cells before and after PCM4 treatment. Scale bar, 10 µm. Data are represented as means ± SEM. Statistical significance was determined by two-tailed Student’s t test. P value: 3.74 × 10-13. g Effect of PCM4 on MYC ubiquitination. Extracts of PCON- and PCM4-treated Raji cells were IP with an anti-Ub Ab. Ubiquitinated MYC was detected by immunoblotting. h In vitro ubiquitination assays show that the CM4 peptide restored the polyubiquitination of MYC. i Effect of PCM4 on MYC protein degradation. Raji cells were treated with CHX (10 µg/mL) and the PCON or PCM4 peptide (4 µm) for the indicated times. The protein abundance of MYC was detected by immunoblotting. j Effect of PCM4 treatment on MYC protein levels. Jurkat cells were treated with PCON or PCM4 for the indicated times (4 µm). The protein expression of MYC was detected by immunoblotting. k The transcriptional activity of MYC in Raji cells treated with PCON or PCM4. PCON- or PCM4-treated Raji cells were transfected with the reporter genes with MYC transcriptional activity. After 24 h of transfection, luciferase activities were measured. Data are represented as means ± SEM. Statistical significance was determined by two-tailed Student’s t test. P value: 0.0058. l GSEA shows global downregulation of MYC target genes in PCM4-treated versus PCON-treated cells. m Metagene plots of global RNAPII occupancy at gene bodies in PCON- or PCM4-treated Raji cells. n ChIP-sequencing tracks for CCNA2 from PCM4-treated cells versus PCON-treated cells normalized to spike-in controls. o PCM4 decreased the serial colony formation ability (P1 and P2) of primary human DLBCL cells (T69). Data are represented as means ± SEM. Statistical significance was determined by two-tailed Student’s t test. P value: 0.0012, 3.403 × 10-5. p Effects of PCM4 on the cell viabilities of the indicated lymphoma and leukemia cells for the indicated times. The colors represent different time points; the diameter indicates the relative cell viability. q Expression of MYC and TRIB3 in the indicated cells. r The synergetic effect of PCM4 and DOX on the cell viability of Raji cells. Source data are provided as a Source Data file.

Fig 3: Combination of PCM4 with doxorubicin inhibits synergistically lymphoma in PDX models.a Strategy for constructing patient-derived tumor xenograft (PDX) models from lymphoma patients. b, c Effects of the indicated treatments on tumor growth in the indicated PDX models. Tumors were subcutaneously engrafted in NSG mice (n = 8 per group). One day later, the mice were treated with PCM4 (5 mg/kg) or/and DOX (2 mg/kg) for 21 days, and the tumors were measured twice a week. Data are represented as means ± SEM. d, e Effects of the indicated treatments on the tumor weights in the indicated PDX models. (DLBCLT64 n = 8 per group, DLBCLT69 n = 6 per group, PTCLT144 n = 5 per group, TLBLT123 n = 6 per group, FLT174 n = 6 per group, DLBCLT169 n = 6 per group, DLBCLT156 n = 6 per group). Data are represented as means ± SEM. Statistical significance was determined by two-tailed Student’s t test. P values were indicated in the panels d and e. f–h Effects of the indicated treatments on the tumor growth and tumor weights in the indicated PDX models. (FLT151 n = 6 per group, DLBCLT1 n = 6 per group, TCLT3 n = 6 per group). Data are represented as means ± SEM. P values were indicated in the panel h. i The expression of MYC and TRIB3 in 13 primary lymphoma cells was detected by western blotting. The dashed line showed the two gels which were probed in parallel. The data are representative of three independent assays. j Statistical analyses of IHC staining of TRIB3 in human lymphoma (n = 37 samples) and benign lymph node (LN) tissues (n = 11 samples). TRIB3 expression was assessed as integrated optical density (IOD) scores. The horizontal lines shown in the graphs represent the median of each protein expression level. The data are presented as the means ± SEM. Statistical significance was determined by two-tailed Student’s t test. P value: 1.29 × 10-8. k Representative images of IHC staining of TRIB3 and MYC in human lymphoma tissues. The data are representative of three independent assays. Scale bars, 100 µm. l Correlation between TRIB3 and MYC expression in human LNs and lymphoma specimens (n = 48). Each data point represents the value from an individual patient. Statistical significance was measured by Pearson’s correlation test. Source data are provided as a Source Data file.

Fig 4: TRIB3 interacts with MYC to inhibit the UBE3B:MYC axis.a In vitro ubiquitination assays show that the TRIB3 or TRIB3-KDC protein decreased polyubiquitination of MYC mediated by UBE3B and UBCH3. b The TRIB3 protein or the KDC domain of TRIB3 decreased the interaction of MYC and UBE3B in the purified system. c Neither the TRIB3 protein nor the KDC domain of TRIB3 affected the interaction of UHCH3 and UBE3B in the purified system. d The interaction of TRIB3 and MYC in Raji cells was evaluated by Co-IP assays. e Colocalization of TRIB3 and MYC in Raji cells was detected with immunostaining (PLA assay). Data are representative images from three independent experiments. Scale bar, 2 µm. f Mapping TRIB3 regions binding to MYC. Top: deletion mutants of TRIB3. Bottom: HEK 293T cells were cotransfected with the indicated constructs of TRIB3 (HA tag) and MYC (Flag tag). Cell extracts were IP with an anti-Flag Ab. g, h Mapping MYC regions binding to TRIB3 (g) or UBE3B (h). Top: deletion mutants of MYC. Bottom: HEK293T cells were cotransfected with the indicated constructs of MYC and TRIB3 or UBE3B. Cell extracts were IP with an anti-Flag Ab. i TRIB3 overexpression interfered with the interaction of UBE3B and MYC. HEK 293T cells were cotransfected with the indicated constructs. Cell extracts were IP with an anti-MYC Ab. j TRIB3 decreased the binding of UBE3B and MYC. Kinetic interactions of the UBE3B and MYC proteins were determined by SPR analyses with the BSA or TRIB3 proteins. k TRIB3 overexpression increased the interaction of MAX and MYC. HEK 293T cells were cotransfected with the indicated constructs. Cell extracts were IP with an anti-MYC Ab. l TRIB3 overexpression increased the binding of MAX and MYC. Kinetic interactions of the MAX and MYC proteins were determined by SPR analyses with the CTRL (GST) or TRIB3 (TRIB3-GST) protein. m The heterotrimers of MYC, TRIB3, and MAX in Raji cells were detected by Co-IP assays. Cellular extracts were IP with mouse IgG as a negative control or anti-MYC, anti-TRIB3, or anti-MAX antibodies. Western blots were performed with anti-MYC, anti-TRIB3, and anti-MAX antibodies. n Recovery of the TRIB3-HA wild-type or KDC-HA mutant enhanced the decreased cell viabilities of TRIB3Cas9 Jurkat cells for the indicated times. The colors represent different time points; the diameter indicates the relative cell viability. Source data are provided as a Source Data file.

Fig 5: WBC100 directly binds to c-Myc protein. A) Colocalization analysis of WBC100-FITC (green) with nuclear RFP-c-Myc protein (red) in HEK293T cells after treatment 10 × 10-6 m WBC100-FITC for 24 h. WBC100-FITC (green) was colocalized with c-Myc protein (red) and induced apoptosis (circled) of c-Myc overexpressing cells. RFP: red fluoresce protein. Scale bars: 10 µm. B) Competition pull-down assay of cellular c-Myc protein by WBC100-FITC. Cancer cellular c-Myc protein was precipitated by WBC100-FITC and preincubation of excessive unlabeled WBC100 reduced the formation of WBC100-c-Myc complexes. C) Western blot analysis for recombinant c-Myc protein after WBC100-FITC or FITC (negative control) pull-down assay. D) Surface plasmon resonance (SPR) results showed the binding of WBC100 to c-Myc protein in a dose-dependent manner. E) Binding site mapping of WBC100-FITC to c-Myc protein using HA-tagged c-Myc (HA-c-Myc) protein mutants and co-IP assay. WT: wild-type protein.