Splicing variant profiles and single nucleotide polymorphisms of the glucocorticoid receptor gene in relation to glucocorticoid sensitivity of B-cell precursor acute lymphoblastic leukaemia.

Abstract

Glucocorticoid (GC) shows antileukaemic activity via binding to the GC receptor (GR). The human GR gene has 4 splicing variants besides the functional isoform GRα, but their significance in GC sensitivity of acute lymphoblastic leukaemia (ALL) has been inconsistent. Additionally, several studies evaluated the relevance of GR gene single nucleotide polymorphisms (SNPs) in the GC sensitivity of ALL, but the current cumulative evidence appears inconclusive. Addressing limitations in previous studies, we used a large series of B-cell precursor ALL (BCP-ALL) cell lines established from Japanese patients to comprehensively examine all 5 splicing variants of the GR gene and candidate SNPs, and their association with GC-sensitivity. We performed real-time reverse transcription polymerase chain reaction (RT-PCR) analyses with 10 sets of primers that differentially quantify the 5 isoforms in different combinations, and the strongest correlations with GC sensitivity were observed for the real-time RT-PCR of exons 7 and 8 (prednisolone sensitivity; r=-0.534, R2 =0.29, P=1.4×10-6 ) and exons 8 and 9a (r=-0.583, R2 =0.34, P=7.6×10-8 ), both specific for GRα and GRγ isoforms. In contrast, the real-time RT-PCR of junction of exons 3g and 4 and exon 4, specific for GRγ isoform alone, did not show significant correlation with GC sensitivity (prednisolone sensitivity; r=-0.403, R2 =0.16, P=4.6×10-4 ). These observations are consistent with the notion that GRα plays a central role in the GC-mediated proapoptotic activity in BCP-ALL. In addition, a promoter region SNP genotype (rs72555796) showed a significant association with GC sensitivity (prednisolone sensitivity; P=.010) and tended to show an association with GR gene expression (RT-PCR of exons 7 and 8; P=.170). These findings indicate that isoform profiles and SNP genotypes of the GR gene may be useful indicators of GC sensitivity in BCP-ALL.