Discovery of a small-molecule inhibitor of specific serine residue BAD phosphorylation

Pandey, Vijay and Wang, Baocheng and Mohan, C. D. and Raquib, Ainiah Rushdiana and Shobith, R. and Srinivasa, V. and Fuchs, Julian E. and Girish, K. S. and Zhu, Tao and Bender, A. and Ma, Lan and Yin, Zhinan and Basappa and Rangappa, K. S. and Lobie, Peter E. (2018) Discovery of a small-molecule inhibitor of specific serine residue BAD phosphorylation. Proceedings of the National Academy of Sciences, 115 (44). E10505-E10514. ISSN 1091-6490

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Despite the initial success of therapeutic agents targeting the RAS/MAP kinase and PI3K/AKT/mTOR signalling networks in oncology, development of acquired resistance to such therapeutics represents a significant challenge in successful disease management. BCL-2–associated death promoter (BAD) is a common and core downstream molecule for both the RAS/MAP kinase and PI3K/AKT/mTOR pathways and regulates cancer cell survival. In its unphosphorylated state, BAD sequesters BCL-2, which results in BAK/BAX activation and apoptosis. Herein, we identified and characterized a small molecule which specifically inhibits BAD phosphorylation on Ser99. This molecule may be therapeutically useful, either alone or in combination, to delay or obviate the development of resistance to other therapeutic agents.Human BCL-2–associated death promoter (hBAD) is an apoptosis-regulatory protein mediating survival signals to carcinoma cells upon phosphorylation of Ser99, among other residues. Herein, we screened multiple small-molecule databases queried in a Laplacian-modified naive Bayesian-based cheminformatics platform and identified a Petasis reaction product as a site-specific inhibitor for hBAD phosphorylation. Based on apoptotic efficacy against mammary carcinoma cells, N-cyclopentyl-3-((4-(2,3-dichlorophenyl) piperazin-1-yl) (2-hydroxyphenyl) methyl) benzamide (NPB) was identified as a potential lead compound. In vitro biochemical analyses demonstrated that NPB inhibited the phosphorylation of hBAD specifically on Ser99. NPB was observed to exert this effect independently of AKT and other kinase activities despite the demonstration of AKT-mediated BAD-Ser99 phosphorylation. Using a structure-based bioinformatics platform, we observed that NPB exhibited predicted interactions with hBAD in silico and verified the same by direct binding kinetics. NPB reduced phosphorylation of BAD-Ser99 and enhanced caspase 3/7 activity with associated loss of cell viability in various human cancer cell lines derived from mammary, endometrial, ovarian, hepatocellular, colon, prostatic, and pancreatic carcinoma. Furthermore, by use of a xenograft model, it was observed that NPB, as a single agent, markedly diminished BAD phosphorylation in tumor tissue and significantly inhibited tumor growth. Similar doses of NPB utilized in acute toxicity studies in mice did not exhibit significant effects. Hence, we report a site-specific inhibitor of BAD phosphorylation with efficacy in tumor models.

Item Type: Article
Subjects: C Chemical Science > Chemistry
Divisions: Department of > Chemistry
Depositing User: LA manjunath user
Date Deposited: 16 Oct 2019 11:33
Last Modified: 17 Jun 2022 10:35

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