iPSC-Derived Glioblastoma Cells Have Enhanced Stemness Wnt/β-Catenin Activity Which Is Negatively Regulated by Wnt Antagonist sFRP4

SIMPLE SUMMARY: Cancer is the second most complex disease after cardiovascular disease. Glioblastoma multiforme (GBM) is a heterogeneous tumor in which the small population of cancer stem cells (CSCs) confers tumors with stemness, relapse and chemotherapeutic resistance. The complete knowledge of the key factors driving CSCs is unclear. This emphasizes the need of the CSC model to understand molecular mechanisms. However, to date, a rapid and readily available in vitro model of GBM of human origin has not been available. In this study, we demonstrated the generation of induced pluripotent stem cells (iPSCs) from a perinatal source amniotic membrane-derived mesenchymal stem cell (AMMSC). A rapid iPSC-derived GBM model exhibiting upregulated canonical Wnt/β-catenin activity was then established. Further, the upregulated Wnt activity could be inhibited by the Wnt antagonist sFRP4. Our study will provide a rapid and easy cell-based platform for understanding the underlying mechanisms of GBM progression and help in assessing chemotherapeutic drugs. ABSTRACT: Growing evidence indicates that cancer stem cells (CSCs) endow the tumor with stem-like properties. Recently, induced pluripotent stem cells (iPSCs) have gained increased attention because of their easy derivation and availability and their potential to differentiate into any cell type. A CSC model derived from iPSCs of human origin would help understand the driving force of tumor initiation and early progression. We report the efficient generation of feeder-free SSEA4, TRA-1-60 and TRA-1-81 positive iPSCs from amniotic membrane-derived mesenchymal stem cells (AMMSCs), which successfully differentiated into three germ layers. We then developed human iPSC-derived glioblastoma multiforme (GBM) model using conditioned media (CM) from U87MG cell line and CSCs derived from U87MG, which confer iPSCs with GBM and GSC-like phenotypes within five days. Both cell types overexpress MGMT and GLI2, but only GSCs overexpress CD133, CD44, ABCG2 and ABCC2. We also observed overexpression of LEF1 and β-catenin in both cell types. Down-regulation of Wnt antagonist secreted frizzled-related protein 4 (sFRP4) in GBM and GSCs, indicating activation of the Wnt/β-catenin pathway, which could be involved in the conversion of iPSCs to CSCs. From future perspectives, our study will help in the creation of a rapid cell-based platform for understanding the complexity of GBM.