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PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
When sorting individual codons by relative occupancy, a primary factor determining translation speed was the nucleotide at the third position.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Whereas codons with adenosine in the third position showed increased occupancy (a proxy for stalling) in ProArg-free diet plus DFMO-treated tumours, occupancy at codons with guanosine in the third position was markedly decreased (Fig. 4d and Extended Data Fig. 6j).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
The same phenotype, with a reduced effect size, was shown for the DFMO monotherapy group, suggesting a previously unknown role of polyamines (rather than low arginine or proline) in the decoding of codons with adenosine at the third position (also referred to as the ‘wobble’ position) (Fig. 4e and Extended Data Fig. 6k–n).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Similarly, at the global level this phenotype was not identified following genetic or pharmacological inhibition of hypusination (Supplementary Fig. 4).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
On the contrary, ribosome pausing appeared to be driven by disrupted codon–anticodon interactions with tRNAs exhibiting complex biochemical modifications at the anticodon wobble base position (tRNA base 34) of all highly paused codons with adenosine in the third position, as well as the two highly paused codons with thymidine in the third position (Fig. 4d).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
This was further supported by the pausing phenotype affecting all three ribosome sites (A, P and E; Extended Data Fig. 6j).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Whereas this was mostly independent of the tRNA modification status at position 34, the ProArg-free diet itself increased queuosine-related modifications, putatively further adding to the polyamine induced codon-specific translation imbalance (Supplementary Fig. 5a–d).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Although interactions of polyamines with ribosomes and tRNAs have been reported and documented to stimulate translation in vitro, to our knowledge, this codon resolution phenotype has not previously been described (Fig. 4e).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
To better understand the phenotypic consequences induced by this specific translation defect, we integrated RNA-sequencing (RNA-seq), Ribo-seq and proteomics data (Fig. 5a and Supplementary Fig. 6a–d).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
The main driver of transcriptional changes was DFMO.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
The ProArg-free diet itself induced only minor such changes, and transcriptional changes strongly overlapped between DFMO alone and the combined ProArg-free diet plus DFMO treatment.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
By contrast, Ribo-seq and proteomics revealed distinct changes in tumours under combined ProArg-free diet plus DFMO therapy.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
The effect was independent of proline or polyproline abundance in the proteins (Supplementary Fig. 6e–h), and instead correlated with genes that were enriched in codons with adenosine in the third position.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Fig. 5Regulation of translation by polyamine depletion is driven by fractional codon content.a, Gene set enrichment analysis (GSEA) of protein biosynthesis using omics layers: gene-expression (RNA-seq), gene translation (Ribo-seq) and protein (proteomics) levels.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
GSEA compares ProArg-free plus DFMO to CD using the Reactome gene sets.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
All pathways are depicted, ranked by significance (Benjamini–Hochberg correction) and signed by normalized enrichment score (NES).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
The most downregulated and upregulated sets at the protein level are cell cycle and neuronal system, respectively.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Lines connect gene sets across the omics layers.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
b, Mean fraction of codons with adenosine in the third position (A-ending codons) across all pathways and significantly changed pathways identified in a. Pathways taken from Reactome gene sets.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
c, The percentage of codons with adenosine in the third position correlates with the average protein level across Reactome pathways.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Pathways with an increasing fraction of codons with adenosine in the third position have lower protein levels in ProArg-free DFMO compared with CD.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
FC, fold change.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
d, Fold change across omics layers of top downregulated cell cycle proteins indicates that differences between ProArg-free diet plus DFMO and CD occur predominantly on the protein level.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
e, Percentage of codons with the respective nucleotide at the third position in the Itgb3bp gene (encoding CENPR protein) compared with the transcriptome background.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
In a,c,d, RNA-seq, ProArg-free + DFMO: n = 5; CD: n = 4.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Ribo-seq, n = 5.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Proteomics, ProArg-free + DFMO: n = 6; CD: n = 5.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Panels a and b created in BioRender.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Morscher, R. (2025) https://BioRender.com/ygrgncb (a); https://BioRender.com/566gynw (b).Source data a, Gene set enrichment analysis (GSEA) of protein biosynthesis using omics layers: gene-expression (RNA-seq), gene translation (Ribo-seq) and protein (proteomics) levels.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
GSEA compares ProArg-free plus DFMO to CD using the Reactome gene sets.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
All pathways are depicted, ranked by significance (Benjamini–Hochberg correction) and signed by normalized enrichment score (NES).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
The most downregulated and upregulated sets at the protein level are cell cycle and neuronal system, respectively.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Lines connect gene sets across the omics layers.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
b, Mean fraction of codons with adenosine in the third position (A-ending codons) across all pathways and significantly changed pathways identified in a. Pathways taken from Reactome gene sets.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
c, The percentage of codons with adenosine in the third position correlates with the average protein level across Reactome pathways.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Pathways with an increasing fraction of codons with adenosine in the third position have lower protein levels in ProArg-free DFMO compared with CD.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
FC, fold change.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
d, Fold change across omics layers of top downregulated cell cycle proteins indicates that differences between ProArg-free diet plus DFMO and CD occur predominantly on the protein level.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
e, Percentage of codons with the respective nucleotide at the third position in the Itgb3bp gene (encoding CENPR protein) compared with the transcriptome background.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
In a,c,d, RNA-seq, ProArg-free + DFMO: n = 5; CD: n = 4.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Ribo-seq, n = 5.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Proteomics, ProArg-free + DFMO: n = 6; CD: n = 5.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Panels a and b created in BioRender.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Morscher, R. (2025) https://BioRender.com/ygrgncb (a); https://BioRender.com/566gynw (b).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Source data Notably, upon combined ProArg-free diet plus DFMO treatment, gene sets linked to neuronal differentiation and neuronal cell identity were the most upregulated at the protein level.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
By contrast, ‘cell cycle’ was the most downregulated gene set, despite exhibiting unchanged RNA expression (Fig. 5a and Extended Data Fig. 7a).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
We next assessed whether the slow translation of codons with adenosine at the third position relates to proteome reprogramming.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Indeed the cell cycle gene set contained a higher frequency of codons with adenosine in the third position that were affected by ribosome pausing, compared with the average for the exome.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Exome-wide, pathways associated with cell cycle programmes were the most enriched in codons with adenosine in the third position.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Neuronal differentiation-associated gene sets were at the opposite end of the spectrum, with the guanosine content showing limited variation in both gene sets (Fig. 5b and Extended Data Fig. 7b–d).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
A higher fraction of codons with adenosine in the third position within a pathway was linked with a lower protein fold change or gene set enrichment (Fig. 5c and Extended Data Fig. 7e).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Beyond the general reduction of cell cycle proteins, four mitosis-related proteins stood out with the strongest downregulation at the protein level under combined ProArg-free diet plus DFMO treatment (Extended Data Fig. 7f,g).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
All four showed at least fourfold downregulation at the protein level, without changes in gene expression (Fig. 5d), in contrast to the regulation in neuronal proteins (Extended Data Fig. 7h,i).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Itgb3bp, encoding CENPR, the most affected protein, showed a remarkably shifted distribution in codon preference, with 38.6% of codons having adenosine in the third position, compared with 18.8% across all protein-coding transcripts (Fig. 5e and Extended Data Fig. 7j,k).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
The ribosome distribution along the CENPR coding sequence confirmed preferential pausing at codons with adenosine in the third position upon ProArg-free diet plus DFMO treatment, as indicated by an increased ribosomal pausing sum at codons with adenosine in the third position and reduced pausing at those with guanosine in the third position (Extended Data Fig. 7l–n).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Similar pausing was observed for CEP57 and KIF2C, and the pausing sum correlated to the levels of the most regulated proteins across the two gene sets (Extended Data Fig. 7o,p).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Expression of cell cycle proteins was increased in MYCN-amplified tumours from human patients and correlated to high tumour stage (Extended Data Fig. 8a–c).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Depleting polyamine levels independently of DFMO by ODC knockdown depleted cell cycle protein levels and induced growth defects characterized by cell cycle arrest (Extended Data Fig. 8d–m).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Conversely, external supplementation of polyamines restored cell growth and CENPR levels following enhanced polyamine depletion by DFMO with proline- and arginine-reduced medium.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
This rescue was independent of hypusination status, as indicated by sustained rescue upon Dhps knockdown, preventing spermidine-dependent post-translational modification of eIF5a (Extended Data Fig. 8n).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Thus, polyamine depletion by combined ProArg-free diet and DFMO treatment induces ribosome stalling at codons with adenosine in the third position.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Owing to the selective enrichment of these codons cell cycle genes and their depletion in differentiation genes, this effect of ProArg-free diet and DFMO treatment reprogrammes the proteome in a manner that favours differentiation.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
We hypothesized that the shift away from cell cycle proteins towards neuronal differentiation proteins is likely to reprogramme neuroblastoma tumours in a manner that slows proliferation and induces differentiation.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Ki67 staining confirmed a decrease in actively cycling cells under ProArg-free diet plus DFMO treatment (Extended Data Fig. 9a).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Furthermore, cell growth activation signatures including MYC and E2F targets were impaired (Fig. 6a and Extended Data Fig. 9b).Fig.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
6Polyamine depletion-mediated proteome rewiring induces neuroblastoma differentiation.a, GSEA across omics layers in all three treatment groups using the Hallmark gene set.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Only the ProArg-free plus DFMO treatment group showed a significant effect compared with CD.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
The effect was mainly on the translation and protein level.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Shown are the five top enriched sets (complete sets in Extended Data Fig. 10c).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Size indicates P value (Benjamini–Hochberg correction) and colour represents NES, with red indicating enrichment in the intervention group (CD + DFMO, ProArg-free or ProArg-free + DFMO) and blue indicating enrichment in the CD group.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
b, Western blot analysis of MYCN in tumours from CD and ProArg-free plus DFMO treatment arms.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Negative control (C1), CHLA20 neuroblastoma cell line (MYCN non-amplified, MYC expressing); positive control (C2), IMR5 neuroblastoma cell line (MYCN-amplified).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
GAPDH is used as a loading control.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Blots are representative of two independent experiments yielding similar results.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
c, Representative haematoxylin and eosin (H&E)-stained sections.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
CD and ProArg-free diet treatments show undifferentiated primitive neuroblasts, absent neuropil and prominent mitotic figures.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
CD plus DFMO shows poorly differentiated primitive neuroblasts with scant neuropil (arrowhead) and foci of cytodifferentiation (<5% differentiating, arrow).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
ProArg-free diet plus DFMO tumours show high fractions of differentiating neuroblasts (>5% differentiating) with increased cytoplasmic to nuclear ratio (arrow) and abundant neuropil (arrowhead).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Sections are representative of many images with the same observations.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Scale bars, 50 μm.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
d, Summary of treatment effects.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Cell cycle and MYCN programmes are downregulated at the protein level owing to translation inhibition and immature cancer cells are driven into neuronal differentiation.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
In a,c, RNA-seq: ProArg-free DFMO: n = 5; CD: n = 4.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Ribo-seq: n = 5.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Proteomics: ProArg-free DFMO: n = 6; CD: n = 5.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Panel d created in BioRender.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Morscher, R. (2025) https://BioRender.com/kk9n051.Source data a, GSEA across omics layers in all three treatment groups using the Hallmark gene set.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Only the ProArg-free plus DFMO treatment group showed a significant effect compared with CD.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
The effect was mainly on the translation and protein level.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Shown are the five top enriched sets (complete sets in Extended Data Fig. 10c).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Size indicates P value (Benjamini–Hochberg correction) and colour represents NES, with red indicating enrichment in the intervention group (CD + DFMO, ProArg-free or ProArg-free + DFMO) and blue indicating enrichment in the CD group.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
b, Western blot analysis of MYCN in tumours from CD and ProArg-free plus DFMO treatment arms.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Negative control (C1), CHLA20 neuroblastoma cell line (MYCN non-amplified, MYC expressing); positive control (C2), IMR5 neuroblastoma cell line (MYCN-amplified).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
GAPDH is used as a loading control.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Blots are representative of two independent experiments yielding similar results.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
c, Representative haematoxylin and eosin (H&E)-stained sections.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
CD and ProArg-free diet treatments show undifferentiated primitive neuroblasts, absent neuropil and prominent mitotic figures.
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
CD plus DFMO shows poorly differentiated primitive neuroblasts with scant neuropil (arrowhead) and foci of cytodifferentiation (<5% differentiating, arrow).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
ProArg-free diet plus DFMO tumours show high fractions of differentiating neuroblasts (>5% differentiating) with increased cytoplasmic to nuclear ratio (arrow) and abundant neuropil (arrowhead).
PMC12527938
Reprogramming neuroblastoma by diet-enhanced polyamine depletion
Sections are representative of many images with the same observations.