Sophoraflavanone G from Phit-Sanat (Sophora Exigua Craib) inhibits WT1 protein expression and induces cell cycle arrest and apoptosis in acute myeloid leukemia.

Abstract

Background: Sophora Exigua Craib, also known as Phit-Sanat in Thai, belongs to the Fabaceae family. The root of S. exigua has been used in Kheaw-Hom, a Thai traditional remedy, for fever treatment. Bioactive compounds from S. exigua have been reported to exhibit health-promoting effects, including anticancer activity. However, their anti-leukemic properties have not yet been elucidated.

Methods: The study employed the MTT assay to evaluate the cytotoxic effects on leukemic cell lines (KG-1a and EoL-1) and PBMCs. Active compounds were purified using column chromatography and further characterized by NMR spectroscopy. Cell cycle distribution and apoptosis were assessed using appropriate kits and analyzed via flow cytometry. The expression of Wilms' tumor 1 (WT1) protein was examined by Western blot analysis. Proteomic analysis was conducted using online software to investigate gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment.

Results: The ethyl acetate (EtOAc) crude fractional extract from S. exigua No. 010 (collected from Chaiyaphum province, Thailand) exhibited strong cytotoxicity in vitro toward both KG-1a and EoL-1 cells. Two active compounds, sophoraflavanone G (SG) and exiguaflavanone B (EGF-B), were isolated from EtOAc No. 010. EtOAc No. 010, SG, and EGF-B suppressed the proliferation of KG-1a and EoL-1 cells in a time- and dose-dependent manner by inducing G1 cell cycle arrest and apoptotic cell death. In this study, EtOAc No. 010, SG, and EGF-B were found to reduce WT1 expression in KG-1a and EoL-1 cells in a dose-dependent manner, with SG exhibiting greater activity than EGF-B. Additionally, KEGG pathway enrichment analysis of the differentially expressed proteins in KG-1a cells following SG treatment revealed significant enrichment in cell cycle regulation, apoptosis, and in the pathways associated with WT1protein expression, including AMPK, VEGF, and mTOR pathways.

Conclusion: The SG isolated from S. exigua, exerts antiproliferative activity towards leukemic cells.