Development of Small-Molecule PUMA Inhibitors for Mitigating Radiation-Induced Cell Death

Gabriela      Mustata; Mei      Li; Nicki      Zevola; Ahmet      Bakan; Lin      Zhang; Michael      Epperly; Joel      S. Greenberger; Jian      Yu; Ivet      Bahar

Abstract

PUMA (p53 upregulated modulator of apoptosis) is a Bcl-2 homology 3 (BH3)-only Bcl-2 family member and a key mediator of apoptosis induced by a wide variety of stimuli. PUMA is particularly important in initiating radiation induced apoptosis and damage in the gastrointestinal and hematopoietic systems. Unlike most BH3-only proteins, PUMA neutralizes all five known antiapoptotic Bcl-2 members through high affinity interactions with its BH3 domain to initiate mitochondria-dependent cell death. Using structural data on the conserved interactions of PUMA with Bcl-2-like proteins, we developed a pharmacophore model that mimics these interactions. In silico screening of the ZINC 8.0 database with this pharmacophore model yielded 142 compounds that could potentially disrupt these interactions. Thirteen structurally diverse compounds with favorable in silico ADME/Toxicity profiles have been retrieved from this set. Extensive testing of these compounds using cell-based and cell-free systems identified lead compounds that confer considerable protection against PUMA-dependent and radiation-induced apoptosis, and inhibit the interaction between PUMA and Bcl-xL.

Keywords: Inhibition of PUMA-induced apoptosis, Bcl-2 protein family, BH3 domain, protein-protein interactions, pharmacophore modeling, druggability, virtual screening of libraries of small compounds, PUMA Inhibitors, p53 upregulated modulator of apoptosis, Bcl-2 homology, hematopoietic systems, programmed cell death, neurodegenerative diseases, autoimmune disorders, radiotherapy, DNA damage, caspases, mitochondrial apoptotic pathway, cytochrome c, mitochondrial dysfunction, ZINC 8.0 database, ADME/Tox, molecular dynamics, colon cancer cells, adenovirus, DLD1 cells, Adriamycin, cyclin-dependent kinase, p21 KO cells, immunoprecipitation, inflammatory cytokines, reactive oxygen species, chemotherapy, anticancer therapies, CYP2D6 inhibition, Cell Culture, Molecular Probes, Western Blotting