Proteomic screening identifies brusatol targets TGFβRII to suppresses non-small cell lung cancer metastasis

Abstract

Background: Metastasis remains the leading cause of cancer mortality. The natural product brusatol (Bru) has exhibited promising anticancer activity; however, the target proteins of Bru and the underlying mechanisms in suppressing tumor metastasis remain unclear.

Purpose: We aim to identify the target of Bru and examine its role in suppressing tumor metastasis.

Methods: The human proteome microarrays and biotin-labelled Bru were employed to identify the direct targets of Bru. To evaluate the anti-migration properties of Bru, TGF-β1 overexpressing NSCLC cells were constructed, wound-healing and transwell assays were performed. The anti-metastatic effects of Bru were assessed using A549-luciferase cell orthotopic xenografts.

Results: We identified that Bru has a high binding affinity for the TGF-β receptor type-II (TGFβRII) protein by probing biotin-labelled Bru on human proteome microarrays. Bru can directly interact with TGFβRII and then effectively suppress recombinant TGF-β1- or TGF-β1 overexpression-induced phosphorylation of Smad2 and Smad3, leading to reduced expression of epithelial-mesenchymal transition (EMT)-associated proteins and the suppression of NSCLC cell migration and invasion. Furthermore, Bru suppressed TGF-β signaling and exerted anti-metastatic activity in the orthotopic xenografts using A549-luciferase cells overexpressing TGF-β1.

Conclusion: Our findings identified that Bru functions as a novel TGFβRII inhibitor, leading to the abrogation of TGF-β signaling activation and the suppression of NSCLC metastasis.

Keywords: Brusatol; Epithelial-mesenchymal transition; Non-small cell lung cancer; TGF-β signaling; TGFβRII; Tumor metastasis.