Multimodal Discovery of Bavachinin A: A Natural FLT3 Agonist for Treating Thrombocytopenia

Background: Radiation-induced thrombocytopenia (RIT) poses a serious risk to patients with cancer undergoing radiotherapy and leads to hemorrhage and mortality. Unfortunately, effective treatment options for RIT are currently limited.

Purpose: This study aimed to discover active compound from Fructus Psoraleae, a traditional Chinese medicine recognized for its hemostatic properties, and to elucidate its mechanism of action in the treatment of RIT.

Methods: The efficacy of Fructus Psoraleae in treating thrombocytopenia was assessed using network pharmacology. A drug-screening model was built using a naive Bayes algorithm to determine the effective compounds in Fructus Psoraleae. Giemsa staining and flow cytometry were used to evaluate the effects of bavachinin A on megakaryocytes (MK) differentiation. RIT and thrombopoietin (TPO) receptor (c-MPL) knockout (c-MPL) mice were used to assess the therapeutic efficacy of bavachinin A in mitigating thrombocytopenia. Tg (cd41:eGFP) zebrafish were used to investigate the effect of bavachinin A on thrombopoiesis. RNA sequencing (RNA-seq), molecular docking simulations, molecular dynamics simulations, drug affinity responsive target stability assay (DARTS), and biolayer interferometry (BLI) were used to elucidate the molecular mechanisms of action of bavachinin A against thrombocytopenia.

Results: In silico analysis using a drug screening model identified bavachinin A as promising candidate compound derived from Fructus Psoraleae. In vitro experiments demonstrated that Bavachinin A induced MK differentiation. In vivo experiments revealed that bavachinin A augmented platelet levels and improved coagulation in RIT mice, facilitated megakaryopoiesis and platelet levels in c-MPL mice, and accelerated thrombopoiesis in zebrafish. Furthermore, RNA-seq, molecular docking simulations, molecular dynamics simulations, DARTS, and BLI demonstrated that bavachinin A bound directly to fms-like tyrosine kinase 3 (FLT3). Notably, blocking FLT3 or phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway hindered bavachinin-A-induced MK differentiation. However, repressing the TPO/c-MPL signaling pathway had no significant effect.

Conclusion: Bavachinin A promotes MK differentiation and thrombopoiesis by directly binding to FLT3 and activating PI3K/Akt signaling. Importantly, this effect was not dependent on the conventional TPO/c-MPL signaling pathway. This study underscores the translational potential of bavachinin A as a promising novel therapeutic for thrombocytopenia, offering novel insights into TPO-independent mechanisms of thrombopoiesis and establishing a robust multimodal approach for drug discovery.