Reactivation of mutant p53 by a dietary-related compound phenethyl isothiocyanate inhibits tumor growth.
Mutations in the p53 tumor-suppressor gene are prevalent in human cancers. The majority of p53 mutations are missense, which can be classified into contact mutations (that directly disrupts the DNA-binding activity of p53) and structural mutations (that disrupts the conformation of p53). Both of the mutations can disable the normal wild-type (WT) p53 activities. Nevertheless, it has been amply documented that small molecules can rescue activity from mutant p53 by restoring WT tumor-suppressive functions. These compounds hold promise for cancer therapy and have now entered clinical trials. In this study, we show that cruciferous-vegetable-derived phenethyl isothiocyanate (PEITC) can reactivate p53 mutant under in vitro and in vivo conditions, revealing a new mechanism of action for a dietary-related compound. PEITC exhibits growth-inhibitory activity in cells expressing p53 mutants with preferential activity toward p53(R175), one of the most frequent 'hotspot' mutations within the p53 sequence. Mechanistic studies revealed that PEITC induces apoptosis in a p53(R175) mutant-dependent manner by restoring p53 WT conformation and transactivation functions. Accordingly, in PEITC-treated cells the reactivated p53(R175) mutant induces apoptosis by activating canonical WT p53 targets, inducing a delay in S and G2/M phase, and by phosphorylating ATM/CHK2. Interestingly, the growth-inhibitory effects of PEITC depend on the redox state of the cell. Further, PEITC treatments render the p53(R175) mutant sensitive to degradation by the proteasome and autophagy in a concentration-dependent manner. PEITC-induced reactivation of p53(R175) and its subsequent sensitivity to the degradation pathways likely contribute to its anticancer activities. We further show that dietary supplementation of PEITC is able to reactivate WT activity in vivo as well, inhibiting tumor growth in xenograft mouse model. These findings provide the first example of mutant p53 reactivation by a dietary compound and have important implications for cancer prevention and therapy.
Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007, USA.
M
M
Aggarwal
Department of Biochemistry and Molecular and Cellular Biology, Georgetown University, Washington, DC 20007, USA.
R
R
Saxena
Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007, USA.
E
E
Sinclair
Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007, USA.
Y
Y
Fu
Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007, USA.
A
A
Jacobs
Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007, USA.
M
M
Dyba
National Institutes of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
X
X
Wang
Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007, USA.
I
I
Cruz
Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007, USA.
D
D
Berry
Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007, USA.
B
B
Kallakury
Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007, USA.
S C
SC
Mueller
Translational Oncogenomics Unit, Italian National Cancer Institute 'Regina Elena', Rome, Italy.
S D
SD
Agostino
Translational Oncogenomics Unit, Italian National Cancer Institute 'Regina Elena', Rome, Italy.
G
G
Blandino
Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007, USA.
M L
ML
Avantaggiati
Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007, USA.
F-L
FL
Chung
D017209:Apoptosis / Q000187:drug effects; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D064447:Checkpoint Kinase 2 / Q000378:metabolism; D004032:Diet; D006657:Histones / Q000378:metabolism; D006801:Humans; D017879:Isothiocyanates / Q000494:pharmacology*; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D009369:Neoplasms / Q000235:genetics* / Q000473:pathology*; D010084:Oxidation-Reduction; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011487:Protein Conformation; D059748:Proteolysis / Q000187:drug effects; D015533:Transcriptional Activation / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*; D023041:Xenograft Model Antitumor Assays; D015032:Zinc / Q000494:pharmacology
C468783:H2AX protein, human; D006657:Histones; D017879:Isothiocyanates; D050505:Mutant Proteins; D016159:Tumor Suppressor Protein p53; C058305:phenethyl isothiocyanate; D064447:Checkpoint Kinase 2; D064007:Ataxia Telangiectasia Mutated Proteins; C578634:CHEK2 protein, human; D046988:Proteasome Endopeptidase Complex; D015032:Zinc