Characterization of iPSCs derived from low grade gliomas revealed early regional chromosomal amplifications during gliomagenesis

Abstract

Introduction. IDH1 mutation has been identified as a early genetic event driving low grade gliomas (LGGs) and it has been proven to exerts a powerful epigenetic effect. Cells containing IDH1 mutation are refractory to epigenetical reprogramming to iPSC induced by expression of Yamanaka transcription factors, a feature that we employed to study early genetic amplifications or deletions in gliomagenesis. Methods. We made iPSC clones from freshly surgically resected IDH1 mutant LGGs by forced expression of Yamanaka transcription factors. We sequenced the IDH locus and analyzed the genetic composition of multiple iPSC clones by array-based comparative genomic hybridization (aCGH). Results. We hypothesize that the primary cell pool isolated from LGG tumor contains a heterogeneous population consisting tumor cells at various stages of tumor progression including cells with early genetic lesions if any prior to acquisition of IDH1 mutation. Because cells containing IDH1 mutation are refractory to reprogramming, we predict that iPSC clones should originate only from LGG cells without IDH1 mutation, i.e. cells prior to acquisition of IDH1 mutation. As expected, we found that none of the iPSC clones contains IDH1 mutation. Further analysis by aCGH of the iPCS clones reveals that they contain regional chromosomal amplifications which are also present in the primary LGG cells. Conclusions. These results indicate that there exists a subpopulation of cells harboring gene amplification but without IDH1 mutation in the LGG primary cell pool. Further analysis of TCGA LGG database demonstrates that these regional chromosomal amplifications are also present in some cases of low grade gliomas indicating they are reoccurring lesions in glioma albeit at a low frequency. Taken together, these data suggest that regional chromosomal alterations may exist prior to the acquisition of IDH mutations in at least some cases of LGGs.

Reprogramming of Cancer Cells into Induced Pluripotent Stem Cells Questioned

“…Interestingly, 4F-MCF10A showed relatively higher expression of endogenous mRNA and protein level rather than 4F-MCF7. When considering for reprogramming potential, MCF10A seems to be more likely to be reprogrammed than the MCF7, consistent with previous report (22).…”

“…Recent study implies that induction of pluripotency from malignant cancer cells was challenging compared to benign cancer cells (22). However, the exact reason for the differences regarding to reprogramming between malignant and benign cancer cells is unknown.…”

Current biomarker-associated procedures of cancer modeling-a reference in the context of IDH1 mutant glioma

“…Their results demonstrate that cells containing the IDH1 mutation are resistant to reprogramming. Their explanation is the high sensitivity of the pluripotent stem cells to D2HG 59 because when human embryonic stem cells (hESCs) were treated with D2HG for 24 h, the hESCs could not tolerate D2HG and die. They found, however, that reprogrammed colonies showed genetic changes, such as amplification of chromosome Xq23 or chromosome 11 and deletion of chromosome 1p, 4, 19q, and Y, amplification of 1.4 Mb region on chromosome 7q31, with co-amplification of genes located in this region.…”

“…Due to the toxicity of Table 2 Listing/summary of model generation strategies using overexpression of IDH MUT on wild-type background. D2HG on hiPSCs 59 , scientists should investigate ways to by-pass this issue. 2D disease modeling by human iPSC can show some disease phenotypes, but there are no tissue or organ level structures.…”

Structure and Emerging Functions of LRCH Proteins in Leukocyte Biology

“…paratuberculosis infection (Jacobsen et al, 2010;McGovern et al, 2019). Furthermore, gene amplifications of LRCH2 and LRCH3 are associated with tumorigenesis of low grade gliomas and melanomas, respectively (Liu et al, 2019;Williams et al, 2020).…”