Journal: Nature
Article Title: Reprogramming neuroblastoma by diet-enhanced polyamine depletion
doi: 10.1038/s41586-025-09564-0
Figure Lengend Snippet: a) eIF5A hypusination defects detected by isoelectric focusing followed by immunoblotting. Tumors of ProArg-free and CD DFMO arms, showing defective hypusination in only two CD DFMO tumors and five ProArg-free DFMO tumors. Neuroblastoma cell line IMR5 as negative control (PC1), not treated with DFMO, and positive control (PC2), treated for five days with 500 uM of DFMO. Stars denote tumors with a non-hypusinated eIF5A (eIF5A-K47acetyl) band compared to hypusinated band (eIF5A-hyp). b) Neuroblastoma cell line IMR5 (used as positive control in other panels) treated with increasing DFMO concentrations for five days and assessed by immunoblotting with an anti-hypusine antibody. c) eIF5A hypusination defects detected by immunoblotting. Tumors of ProArg-free DFMO show partially reduced hypusination. IMR5 (C1) and CHLA20 (C2) were added as negative controls for comparison to incomplete hypusination. d) Quantification of hypusination by isoelectric blots reported in a) and immunoblots reported in b). Mean ± s.e.m. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, two-tailed t-test. n = 7-8 per group. e) Validation of isoelectric blots bands. IMR5 protein lysates treated with 500 uM DFMO for 5 days. In a single IEF gel, these 3 lysates were run in triplicate, the membrane cut, and independently probed without stripping, using anti-eIF5A (detecting all forms), anti-hypusine (detecting only hypusinated eIF5A), and anti-eIF5A-K47 acetyl (detecting only K47-acetylated forms). f) Schematic of eIF5A hypusination via DHPS using spermidine as a substrate. g) Relative ribosome density in relation to proline codons upon Eif5a and Dhps knock down (KD) as compared to short-hairpin control (sh-contrl). The left panels are centered by poly proline tracts and the right by proline codons outside thereof. In Dhps KD, increased occupancy shows at all proline codons independent of the nucleotide three position (e.g. adenosine-ending). Reprocessed and reanalyzed data from Nakanishi et al. n = 2 per group. h) In vitro translation setup of IMR5 neuroblastoma cell lysates that were harvested in log-phase growth. Lysates were co-incubated with in vitro transcribed mRNA fragments encoding a repeat of either 7 instances of CCA or CCG just 5’ upstream of luciferase. Changes in fluorescent intensity thereby reflect the effect of polyamines on the translation of the codon repeats. i) Polyamine supplementation with 1.5 mM spermidine preferentially facilitates translation of CCA codon repeats, as compared to CCG stretches. Relative fluorescence to baseline translation of two independent experiments are shown. j) Translation defects are codon specific. Relative ribosome density on all amino acid codons in combined drug-diet treatment (ProArg-free DFMO vs. CD). First letter of name denotes amino acid followed by the encoding codon. k) The diet effect (ProArg-free vs. CD) in the ribosomal P site is not driven by pausing at arginine and proline amino acid codons. l) DFMO treatment effect (CD DFMO vs. CD) is characterized by ribosome pausing depending on the nucleotide at the codon-three position in ribosome P site. m) Adding a ProArg-free diet to DFMO treatment is characterized by enhanced ribosome pausing depending on the nucleotide identity at the codon-three position in ribosomal P site (ProArg-free DFMO vs. CD DFMO). Boxplot where the center line represents the median, the box spans the interquartile range (IQR; 25th to 75th percentiles), and whiskers extend to 1.5I QR. Data points beyond this range are shown as outliers (solid black). One-way ANOVA. A-ending codons n = 14, T-ending codons n = 16, G-ending codons n = 15, C-ending codons n = 16. n) Increased pausing at A-ending codons when comparing ProArg-free DFMO vs. CD DFMO at the ribosomal P site. j-n shows mean of n = 5. Abbreviations: CD, control diet; ProArg-free, proline and arginine-free diet; DFMO, difluoromethylornithine. Panels f and h created in BioRender. Morscher, R. (2025) https://BioRender.com/sf37unt (f); https://BioRender.com/7ngicj2 (h).
Article Snippet: For xenografts used in therapeutic trials, tumours were established on 4- to 6-week-old female NCr-nu mice (Charles River) by injection of 100 μl 50/50 RPMI/Matrigel solution containing 3 × 10 6 IMR5 cells ( MYCN amplified, ALK amplified).
Techniques: Western Blot, Negative Control, Positive Control, Comparison, Two Tailed Test, Biomarker Discovery, Membrane, Stripping Membranes, Knockdown, Control, In Vitro, Incubation, Luciferase, Fluorescence