Akin D, Wang SK, Habibzadegah-Tari P, Law B, Ostrov D, Li M, Yin XM, Kim JS, Horenstein N, Dunn WA. A novel ATG4B antagonist inhibits autophagy and has a negative impact on osteosarcoma tumors.
Autophagy 2014;
10:2021-35. [PMID:
25483883 PMCID:
PMC4502682 DOI:
10.4161/auto.32229]
[Citation(s) in RCA: 157] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Autophagy has been implicated in the progression and chemoresistance of various cancers. In this study, we have shown that osteosarcoma Saos-2 cells lacking ATG4B, a cysteine proteinase that activates LC3B, are defective in autophagy and fail to form tumors in mouse models. By combining in silico docking with in vitro and cell-based assays, we identified small compounds that suppressed starvation-induced protein degradation, LC3B lipidation, and formation of autophagic vacuoles. NSC185058 effectively inhibited ATG4B activity in vitro and in cells while having no effect on MTOR and PtdIns3K activities. In addition, this ATG4B antagonist had a negative impact on the development of Saos-2 osteosarcoma tumors in vivo. We concluded that tumor suppression was due to a reduction in ATG4B activity, since we found autophagy suppressed within treated tumors and the compound had no effects on oncogenic protein kinases. Our findings demonstrate that ATG4B is a suitable anti-autophagy target and a promising therapeutic target to treat osteosarcoma.
Collapse