Reactivation of mutant p53 by capsaicin, the major constituent of peppers.
Mutations in the p53 oncosuppressor gene are highly frequent in human cancers. These alterations are mainly point mutations in the DNA binding domain of p53 and disable p53 from transactivating target genes devoted to anticancer activity. Mutant p53 proteins are usually more stable than wild-type p53 and may not only impair wild-type p53 activity but also acquire pro-oncogenic functions. Therefore, targeting mutant p53 to clear the hyperstable proteins or change p53 conformation to reactivate wild-type p53 protein functions is a powerful anticancer strategy. Several small molecules have been tested for p53 reactivation in mutant p53-carrying cells while studies exploiting the effect of natural compounds are limited. Capsaicin (CPS) is the major constituent of peppers and show antitumor activity by targeting several molecular pathway, however, its effect on mutant p53 reactivation has not been assessed yet. In this study we aimed at investigating whether mutant p53 could be a new target of capsaicin-induced cell death and the underlying mechanisms.



p53 levels were analysed by western blot upon capsaicin treatment in the presence of the autophagy inhibitor chloroquine. The mutant p53 reactivation was evaluated by chromatin-immunoprecipitation (ChIP) assay and semi-quantitative RT-PCR analyses of wild-type p53 target genes. The specific wild-type p53 activation was determined by using the inhibitor of p53 transactivation function, pifithrin-α and siRNA for p53.



Here, we show that capsaicin induced autophagy that was, at least in part, responsible of mutant p53 protein degradation. Abrogation of mutant p53 by capsaicin restored wild-type p53 activities over mutant p53 functions, contributing to cancer cell death. Similar effects were confirmed in cancer cells bearing tumor-associated p53 mutations and in H1299 (p53 null) with overexpressed p53R175H and p53R273H mutant proteins.



These findings demonstrate for the first time that capsaicin may reduce mutant p53 levels and reactivate wild-type p53 protein in mutant p53-carrying cells and the p53 reactivation contributes to capsaicin-induced cell death.
Regina Elena National Cancer Institute, Department of Research, Advanced Diagnostics, and Technological Innovation, Unit of Cellular Networks and Molecular Therapeutic Targets, Rome, 00144, Italy.|Department of Medical Sciences, Tumor Biology Unit, University "G. d'Annunzio", Chieti, 66013, Italy.
Alessia
A
Garufi
Department of Systems Medicine, University "Tor Vergata", Rome, 00133, Italy.
Giuseppa
G
Pistritto
Department of Experimental Medicine, Istituto Pasteur Fondazione Cenci Bolognetti, University "Sapienza", Rome, 00161, Italy.
Mara
M
Cirone
Regina Elena National Cancer Institute, Department of Research, Advanced Diagnostics, and Technological Innovation, Unit of Cellular Networks and Molecular Therapeutic Targets, Rome, 00144, Italy. gabriella.dorazi@unich.it.|Department of Medical Sciences, Tumor Biology Unit, University "G. d'Annunzio", Chieti, 66013, Italy. gabriella.dorazi@unich.it.
Gabriella
G
D'Orazi
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage* / Q000494:pharmacology; D017209:Apoptosis; D002211:Capsaicin / Q000008:administration & dosage* / Q000494:pharmacology; D002212:Capsicum / Q000737:chemistry; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002738:Chloroquine / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D051379:Mice; D009154:Mutation / Q000187:drug effects; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics; D059748:Proteolysis; D015398:Signal Transduction / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays
D000972:Antineoplastic Agents, Phytogenic; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D002738:Chloroquine; D002211:Capsaicin
Apoptosis; Autophagy; Capsaicin; Mutant p53; Natural compounds; p53; p53 reactivation