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.