AICAR-mediated selection of karyotypically normal cells in Pallister-Killian syndrome patient-derived skin fibroblasts

Abstract

Pallister-Killian Syndrome (PKS) is a mosaic aneuploidy syndrome typically caused by the presence of a supernumerary marker isochromosome containing two extra copies of the short arm of chromosome 12 (iso-chromosome 12p or tetrasomy 12p). This isochromosome is always present in a mosaicism state that has tissue limited distribution. PKS is characterized by severe neurodevelopmental delay, intellectual disability, multisystem involvement and congenital malformations including typical dysmorphic features and skin pigmentation anomalies. Aneuploid cells, irrespective of the identity of the supernumerary chromosome, including cancer cells, yeast cells and mouse embryonic fibroblasts (MEFs), have been demonstrated to present a disruption of protein homeostasis and increased basal stress levels; resulting in a greater sensitivity to chemical compounds inducing cellular energy stress compared to euploid cell lines. The burden of trisomy 21 has also been recently shown to impair the proteostasis network in lymphoblastoid cell lines and fibroblasts obtained from individuals with Down syndrome. In this study, we demonstrate that AICAR, 5-Aminoimidazole-4-carboxamide ribonucleotide, a known energy stress inducing drug with antiproliferative effects on aneuploidy cancer cells and MEFs, is also able to selectively eliminate cells carrying the isochromosme12p in PKS clones in a time and dosage dependent manner. Collectively, our results indirectly provide evidence of increased basal energy and proteotoxic stress in PKS cells carrying isochromosome 12p, and suggest a potential therapeutic drug-based strategy that, selectively acting as a stressor for aneuploid cells, may establish the euploid state in PKS and a broader spectrum of human mosaic disorders.