Modeling human brain rhabdoid tumor by inactivating tumor suppressor genes in induced pluripotent stem cells.

Abstract

Atypical teratoid/rhabdoid tumor (ATRT) is a rare childhood malignancy that originates in the central nervous system. Over ninety-five percent of ATRT patients have biallelic inactivation of the tumor suppressor gene <i>SMARCB1</i>. ATRT has no standard treatment, and a major limiting factor in therapeutic development is the lack of reliable ATRT models. We employed CRISPR/Cas9 gene-editing technology to knock out <i>SMARCB1</i> and <i>TP53</i> genes in human episomal induced pluripotent stem cells (Epi-iPSCs), followed by brief neural induction, to generate an ATRT-like model. The dual knockout Epi-iPSCs retained their stemness with the capacity to differentiate into three germ layers. High expression of <i>OCT4</i> and <i>NANOG</i> in neurally induced knockout spheroids was comparable to that in two ATRT cell lines. Beta-catenin protein expression was higher in SMARCB1-deficient cells and spheroids than in normal Epi-iPSC-derived spheroids. Nucleophosmin, Osteopontin, and Ki-67 proteins were also expressed by the SMARCB1-deficient spheroids. In summary, the tumor model resembled embryonal features of ATRT and expressed ATRT biomarkers at mRNA and protein levels. Ribociclib, PTC-209, and the combination of clofilium tosylate and pazopanib decreased the viability of the ATRT-like cells. This disease modeling scheme may enable the establishment of individualized tumor models with patient-specific mutations and facilitate high-throughput drug testing.