Carcinogenesis Advance Access originally published online on November 28, 2007
Carcinogenesis 2008 29(7):1428-1434; doi:10.1093/carcin/bgm266
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In vitro and in vivo cytotoxic effects of PRIMA-1 on hepatocellular carcinoma cells expressing mutant p53ser249
1 International Agency for Research on Cancer, 150 cours Albert Thomas, 69372 Lyon Cedex 08, France
2 Department of Oncology-Pathology, Cancer Center Karolinska, Karolinska Institutet, Karolinska University Hospital, 171 77 Stockholm, Sweden
3 Unité Institut National de la Santé et de la Recherche Médicale U590, Université Lyon-1, Centre Léon Bérard, 28 rue Laennec, 69373 Lyon Cedex 08, France
* To whom correspondence should be addressed. Tel: +33 472738532; Fax: +33 472738322; Email: hainaut{at}iarc.fr
Hepatocellular carcinoma (HCC) is highly lethal due to limited curative options. In high-incidence regions, such as parts of Africa and Southeastern Asia, >50% of cases carry an AGG to AGT mutation at codon 249 of the TP53 gene, considered as a ‘signature’ of mutagenesis by aflatoxins. The protein product, p53ser249, may represent a therapeutic target for HCC. The small molecule p53 reactivation and induction of massive apoptosis (PRIMA)-1 has been shown to induce apoptosis in tumour cells by reactivating the transactivation capacity of some p53 mutants. In this study, we have investigated the cytotoxic effects of PRIMA-1 on HCC cells expressing p53ser249. In p53-null Hep3B cells, over-expression of p53ser249 or p53gln248 by stable transfection increased the cytotoxicity of PRIMA-1 at 50 µM. Furthermore, PRIMA-1 treatment delayed the growth of p53ser249-expressing Hep3B cells xenografted in severe combined immunodeficiency mice. However, PRIMA-1 did not restore wild-type DNA binding and transactivation activities to p53ser249 or to p53gln248 in Hep3B cells. Moreover, in PLC/PRF/5, a HCC cell line constitutively expressing p53ser249, small interfering RNA (siRNA) silencing of the mutant increased the cytotoxic effect of PRIMA-1. These apparently contradictory effects can be reconciled by proposing that p53ser249 exerts a gain-of-function effect, which favours the survival of HCC cells. Thus, both inhibition of this effect by PRIMA-1 and removal of the mutant by siRNA can lead to the decrease of survival capacity of HCC cells.
Abbreviations: AFB1, aflatoxin B1; COX-2, cyclooxygenase-2; DMSO, dimethyl sulphoxide; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; HBV, hepatitis B virus; HCC, hepatocellular carcinoma; PBS, phosphate-buffered saline; PRIMA, p53 reactivation and induction of massive apoptosis; PUMA, p53-up-regulated modulator of apoptosis; QPCR, quantitative polymerase chain reaction; SCID, severe combined immunodeficiency; siRNA, small interfering RNA; WAF1, wild-type p53-activated fragment 1
Received June 15, 2007; revised November 15, 2007; accepted November 18, 2007.