A Small Molecule Screen Exposes mTOR Signaling Pathway Involvement in Radiation-Induced Apoptosis
| Autor: | George S. Bloom, Ana Lira, Michael W. Epperly, Joel S. Greenberger, Elizabeth R. Sharlow, John S. Lazo, Andrés Norambuena, Stephanie Leimgruber, Michael J. McConnell |
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| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Apoptosis Radiation-Protective Agents mTORC1 Biology Pharmacology Biochemistry Article Cell Line Small Molecule Libraries 03 medical and health sciences medicine Humans PI3K/AKT/mTOR pathway Sirolimus Everolimus TOR Serine-Threonine Kinases Cell Cycle RPTOR General Medicine 030104 developmental biology Molecular Medicine Signal transduction Signal Transduction medicine.drug |
| Zdroj: | ACS Chemical Biology. 11:1428-1437 |
| ISSN: | 1554-8937 1554-8929 |
| Popis: | Individuals are at risk of exposure to acute ionizing radiation (IR) from a nuclear accident or terrorism, but we lack effective therapies to mitigate the lethal IR effects. In the current study, we exploited an optimized, cell-based, high throughput screening assay to interrogate a small molecule library comprising 3437 known pharmacologically active compounds for mitigation against IR-induced apoptosis. Thirty-three library compounds significantly reduced apoptosis when administered 1 h after 4 Gy IR. Two- or three-dimensional computational structural analyses of the compounds indicated only one or two chemical clusters with most of the compounds being unique structures. The mechanistic target of rapamycin complex 1 (mTORC1) inhibitor, rapamycin, was the most potent compound, and it mitigated apoptosis by 50% at 200 ± 50 pM. Other mTOR inhibitors, namely everolimus, AZD8055, and torin 1, also suppressed apoptosis, providing additional pharmacological evidence for mTOR pathway involvement in regulating cell death after IR. Everolimus and torin 1 treatment after IR decreased the S phase population and enforced both G1 and G2 phase arrest. This prorogation of cell cycle progression was accompanied by decreased IR-induced DNA damage measured by γH2AX phosphorylation at Ser139. RNA interference-mediated knockdown of the respective mTORC1 and mTORC2 subunits, Raptor or Rictor, also mitigated IR-induced apoptosis. Collectively, this study suggests a central role for the mTOR signaling in the cytotoxic response to IR and offers a useful platform to probe for additional agents. |
| Databáze: | OpenAIRE |
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