A fluorescent curcumin-based Zn(II)-complex reactivates mutant (R175H and R273H) p53 in cancer cells.
BACKGROUND
Mutations of the p53 oncosuppressor gene are amongst the most frequent aberration seen in human cancer. Some mutant (mt) p53 proteins are prone to loss of Zn(II) ion that is bound to the wild-type (wt) core, promoting protein aggregation and therefore unfolding. Misfolded p53 protein conformation impairs wtp53-DNA binding and transactivation activities, favouring tumor growth and resistance to antitumor therapies. Screening studies, devoted to identify small molecules that reactivate mtp53, represent therefore an attractive anti-cancer therapeutic strategy. Here we tested a novel fluorescent curcumin-based Zn(II)-complex (Zn-curc) to evaluate its effect on mtp53 reactivation in cancer cells.


METHODS
P53 protein conformation was examined after Zn-curc treatment by immunoprecipitation and immunofluorescence assays, using conformation-specific antibodies. The mtp53 reactivation was evaluated by chromatin-immunoprecipitation (ChIP) and semi-quantitative RT-PCR analyses of wild-type p53 target genes. The intratumoral Zn-curc localization was evaluated by immunofluorescence analysis of glioblastoma tissues of an ortothopic mice model.


RESULTS
The Zn-curc complex induced conformational change in p53-R175H and -R273H mutant proteins, two of the most common p53 mutations. Zn-curc treatment restored wtp53-DNA binding and transactivation functions and induced apoptotic cell death. In vivo studies showed that the Zn-curc complex reached glioblastoma tissues of an ortothopic mice model, highlighting its ability to crossed the blood-tumor barrier.


CONCLUSIONS
Our results demonstrate that Zn-curc complex may reactivate specific mtp53 proteins and that may cross the blood-tumor barrier, becoming a promising compound for the development of drugs to halt tumor growth.
Alessia
A
Garufi
Daniela
D
Trisciuoglio
Manuela
M
Porru
Carlo
C
Leonetti
Antonella
A
Stoppacciaro
Valerio
V
D'Orazi
Maria
M
Avantaggiati
Alessandra
A
Crispini
Daniela
D
Pucci
Gabriella
G
D'Orazi
D000818:Animals; D001932:Brain Neoplasms / Q000235:genetics / Q000378:metabolism*; D002413:Cations, Divalent / Q000737:chemistry / Q000494:pharmacology; D016923:Cell Death; D045744:Cell Line, Tumor; D056831:Coordination Complexes / Q000737:chemistry / Q000494:pharmacology*; D003474:Curcumin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004195:Disease Models, Animal; D015870:Gene Expression; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D011487:Protein Conformation; D011897:Random Allocation; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D015032:Zinc / Q000737:chemistry* / Q000494:pharmacology*
D002413:Cations, Divalent; D056831:Coordination Complexes; D016159:Tumor Suppressor Protein p53; D003474:Curcumin; D015032:Zinc