Identification and Characterization of CW108F, a Novel β-carboline Compound That Promotes Cardiomyogenesis of Stem Cells

Aims: The aim of this study was to identify new compounds that induce cardiomyocyte differentiation of stem cells through cell-based screening and investigate lineage specificity and mechanisms in vitro.

Main Methods: Embryoid bodies (EBs) formed from TC-1/KH2 mouse embryonic stem cells (ESCs) carrying the gene for enhanced green fluorescent protein (EGFP) under the control of the α-myosin heavy chain (MHC) promoter were treated with test compounds. The number of cardiomyocyte-like (EGFP-expressing) cells in EBs was determined by fluorescence-activated cell sorting. Cardiomyocyte differentiation was further confirmed using lineage-specific biochemical assays and by investigating the expression of cardiomyocyte-specific and "stemness"-associated genes. Nuclear factor-kappaB (NF-κB) signaling activity was measured in A549 cells using a reporter-gene assay.

Key Findings: A β-carboline compound, designated CW108F, increased the number of mouse ESCs expressing α-MHC promoter-driven EGFP and the proportion of beating EBs. CW108F also increased expression of MHC in P19 stem cells, but did not induce osteogenesis of MC3T3-E1 cells, suggesting lineage-specific activity toward cardiomyocytes. CW108F upregulated expression of cardiac-specific GATA-4 and atrial natriuretic factor (ANF) genes in TC-1/KH2 cells, but downregulated expression of the stemness genes, Oct-4 and brachyury. CW108F inhibited NF-κB transcriptional activity, an effect that might contribute to its cardiomyogenesis-promoting activity.

Significance: The results of this study suggest that the novel β-carboline, CW108F, promotes the differentiation of ESCs into cardiomyocytes and may be useful for investigating molecular pathways of cardiomyogenesis and generating cardiomyocytes from ESCs.