The GTPase KRAS suppresses the p53 tumor suppressor by activating the NRF2-regulated antioxidant defense system in cancer cells
| Autor: | Said M. Sebti, Shengyan Xiang, Aslamuzzaman Kazi, Hua Yang |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Cyclin-Dependent Kinase Inhibitor p21
0301 basic medicine Amino Acid Transport System y+ NF-E2-Related Factor 2 Down-Regulation IκB kinase Protein Serine-Threonine Kinases medicine.disease_cause Proto-Oncogene Mas Biochemistry Antioxidants Malignant transformation Proto-Oncogene Proteins p21(ras) 03 medical and health sciences TANK-binding kinase 1 Cell Line Tumor NAD(P)H Dehydrogenase (Quinone) medicine Humans Phosphorylation RNA Small Interfering neoplasms Molecular Biology RALB Glutathione Disulfide 030102 biochemistry & molecular biology Chemistry Kinase Cell Biology Glutathione GTPase KRas 030104 developmental biology Cancer cell Cancer research RNA Interference ral GTP-Binding Proteins KRAS Tumor Suppressor Protein p53 Reactive Oxygen Species Signal Transduction |
| Zdroj: | J Biol Chem |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.ra119.011930 |
| Popis: | In human cancer cells that harbor mutant KRAS and WT p53 (p53), KRAS contributes to the maintenance of low p53 levels. Moreover, KRAS depletion stabilizes and reactivates p53 and thereby inhibits malignant transformation. However, the mechanism by which KRAS regulates p53 is largely unknown. Recently, we showed that KRAS depletion leads to p53 Ser-15 phosphorylation (P-p53) and increases the levels of p53 and its target p21/WT p53-activated fragment 1 (WAF1)/CIP1. Here, using several human lung cancer cell lines, siRNA-mediated gene silencing, immunoblotting, quantitative RT-PCR, promoter–reporter assays, and reactive oxygen species (ROS) assays, we demonstrate that KRAS maintains low p53 levels by activating the NRF2 (NFE2-related factor 2)–regulated antioxidant defense system. We found that KRAS depletion led to down-regulation of NRF2 and its targets NQO1 (NAD(P)H quinone dehydrogenase 1) and SLC7A11 (solute carrier family 7 member 11), decreased the GSH/GSSG ratio, and increased ROS levels. We noted that the increase in ROS is required for increased P-p53, p53, and p21(Waf1/cip1) levels following KRAS depletion. Downstream of KRAS, depletion of RalB (RAS-like proto-oncogene B) and IκB kinase–related TANK-binding kinase 1 (TBK1) activated p53 in a ROS- and NRF2-dependent manner. Consistent with this, the IκB kinase inhibitor BAY11-7085 and dominant-negative mutant IκBαM inhibited NF-κB activity and increased P-p53, p53, and p21(Waf1/cip1) levels in a ROS-dependent manner. In conclusion, our findings uncover an important role for the NRF2-regulated antioxidant system in KRAS-mediated p53 suppression. |
| Databáze: | OpenAIRE |
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