Year: 2026
Type: conference-abstract
Abstract: Dihydropyrimidine dehydrogenase (DPD, encoded by the DPYD gene) is the rate-limiting enzyme in the catabolism of the widely used chemotherapeutic drug 5-fluorouracil (5-FU).Genetic variations in DPYD are predictive biomarkers of 5-FU toxicity.One such biomarker, rs75017182 (the causal allele linked to the "HapB3" haplotype), has been suggested to promote alternative splicing of DPYD, leading to expression of an inactive proteoform.However, carriers of rs75017182 exhibit only moderately increased risk of 5-FU toxicity and modestly decreased ex vivo DPD activity compared to carriers of another well-studied splice variant, rs3918290 (*2A).We hypothesized that, unlike *2A, the rs75017182 variant does not cause obligate alternative splicing but instead promotes partial alternative splicing.To test this, we generated dual-fluorescent minigene reporter constructs containing either the G (wildtype) or C (variant) allele.In our minigene system, obligate alternative splicing was elevated in cells transfected with C-containing vectors via flow cytometry, rather than partial alternative splicing.To investigate contributions of other variants in LD with rs75017182, we expanded the reporter to include additional relevant genomic regions such as rs56038477 and rs4294451.Compared to rs4294451 A vectors, which is the alternative inactive allele, rs4294451 T active allele vectors showed increased wild type splicing when carrying the rs75017182 C allele, the rs56038477 A allele, or both variants together, suggesting rs4294451 T allele may have a rescue effect.Further analyses were complemented by the study of in vivo splicing in cells engineered to harbor various combinations of variants and in lymphoblastoid lines carrying specific genotype combinations.Overall, our findings demonstrate that rs75017182-C promotes alternative splicing in our minigene plasmid model, and that the level of splicing may be affected by additional variants in linkage disequilibrium with rs75017182.Dihydropyrimidine dehydrogenase, 5-fluorouracil, splicing, biomarker PS01.02
DOI: 10.1002/cpt.70405
Language: English
Subfield: Pharmacology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7203786241