PIGN gene expression aberration is associated with genomic instability and leukemic progression in acute myeloid leukemia with myelodysplastic features

Abstract

Previous studies have linked increased frequency of glycosylphosphatidylinositol-anchor protein (GPI-AP) deficiency with genomic instability and the risk of carcinogenesis. However, the underlying mechanism is still not clear. A randomForest analysis of the gene expression array data from 55 MDS patients (GSE4619) demonstrated a significant (p = 0.0007) correlation (Pearson r =-0.4068) between GPI-anchor biosynthesis gene expression and genomic instability, in which PIGN, a gene participating in GPI-AP biosynthesis, was ranked as the third most important in predicting risk of MDS progression. Furthermore, we observed that PIGN gene expression aberrations (increased transcriptional activity but diminished to no protein production) were associated with increased frequency of GPI-AP deficiency in leukemic cells during leukemic transformation/progression. PIGN gene expression aberrations were attributed to partial intron retentions between exons 14 and 15 resulting in frameshifts and premature termination which were confirmed by examining the RNA-seq data from a group of AML patients (phs001027.v1.p1). PIGN gene expression aberration correlated with the elevation of genomic instability marker expression that was independent of the TP53 regulatory pathway. Suppression/elimination of PIGN protein expression caused a similar pattern of genomic instability that was rescued by PIGN restoration. Finally, we found that PIGN bound to the spindle assembly checkpoint protein, MAD1, and regulated its expression during the cell cycle. In conclusion, PIGN gene is crucial in regulating mitotic integrity to maintain chromosomal stability and prevents leukemic transformation/progression.

PIGN Spatiotemporally Regulates the Spindle Assembly Checkpoint Proteins in Myelodysplastic Syndromes

“…2a-j). We have previously reported increased PIGN gene expression in AML-MRC patient CD34 + PBMCs with partial intron retentions in the PIGN gene compared to normal nonleukemic control cells 15 . In this current study, a signi cant increase in PIGN expression was associated with a signi cant increase in MAD1 expression in AML-MRC patients known to possess partial intron retentions in the PIGN gene.…”

“…The loss of tumor suppressors like TP53, BRD4, and BRCA1 has been associated with altered expression of SAC-related genes, genomic instability, and tumor progression 58,59 . We have previously reported PIGN gene expression aberration-driven genomic instability in leukemic cells that was independent of the TP53-regulatory pathway 15 . Interestingly, TP53 has been shown in multiple studies to transcriptionally regulate the genes encoding MAD1, CDC20, cyclin A1 and cyclin B 58,60 .…”

“…partial intron retention mutation between exons 14 and 15) ( Fig. 2k) 15 . Overall, a regulatory link seems to exist between PIGN and the SAC.…”

“…Western blot analysis was conducted as previously described 15 . Brie y, total protein was extracted using RIPA cell lysis buffer supplemented with phosphatase inhibitor cocktail and protease inhibitor (Sigma).…”

“…Cell cycle synchrony was monitored using propidium iodide-stained cells with the BD FACSCalibur ow cytometer (BD Biosciences, San Jose, CA). Protein lysates were obtained and used for Western blot analyses as described previously 15 .…”