ABCC4 functional SNP in the 3' splice acceptor site of exon 8 (G912T) is associated with unfavorable clinical outcome in children with acute lymphoblastic leukemia.

Abstract

ATP-binding cassette subfamily C member 4 (ABCC4) encoding MRP4 protein is involved in pediatric acute lymphoblastic leukemia (ALL) drug resistance. The nonsynonymous single nucleotide polymorphism (SNP) rs2274407 (G912T; K304N) is located in the 3' splice acceptor site of exon 8 of ABCC4 pre-mRNA. The aim of this study was to investigate the prognostic value of rs2274407 in childhood ALL and its possible functional effect on MRP4. ABCC4 G912T SNP was genotyped in 145 Iranian Philadelphia-negative (Ph-) children with ALL using modified tetra-primer ARMS PCR and evaluated for possible association with 3-year disease-free survival (3DFS). In addition, functional impact of rs2274407 on the MRP4 activity and possible post-transcriptional modifications were bioinformatically and experimentally studied. ABCC4 912T allele carriers (G/T and T/T genotypes) are associated with worse 3DFS in Pre-B cell ALL [P=0.00019, OR (95% CI)=13.17 (2.55-68.11)]. In addition, computational studies showed that K304N alteration has no impact on the MRP4 activity. However, it may disrupt the normal splicing process of ABCC4 pre-mRNA. To date, this is the first study that shows the potential functional impact of rs2274407 SNP on the aberrant splicing of ABCC4 mRNA. We also demonstrated a robust association between G912T and pediatric ALL negative outcome, which may be explained by the novel computational studies performed in this study.