Adenovirus-mediated transfer of wild-type p53 gene sensitizes TNF resistant MCF7 derivatives to the cytotoxic effect of this cytokine: relationship with c-myc and Rb

Abstract

Tumor suppressor p53 is a nuclear transcription factor that blocks cell cycle progression and induces apoptosis. We have previously shown that the MCF7 resistance to the cytotoxic action of TNF correlates with p53 mutations. In the present study, we used a recombinant adenovirus carrying a wild-type p53 gene (Adwtp53) in order to investigate the e ect of wt p53 transfer on modulation of cell resistance to the cytotoxic action of TNF. Our data indicate that infection of TNF resistant MCF7 cells (1001 and MCF7/Adr) with Adwtp53 resulted in the restoration of wt p53 expression and function as respectively revealed by the yeast assay and the induction of p53 inducible genes MDM2 and p21. Furthermore, the restoration of p53 function signi®cantly sensitized TNF resistant cells to TNF cytotoxic action. This correlated with a signi®cant down-regulation of cmyc in both TNF-resistant cell lines and a decrease of Retinoblastoma protein (Rb) in 1001 clone. In contrast, the e ect of p53 seems to be independent from Bcl-2 and Bax protein level regulation. The present study suggests that the combination of TNF and Adwtp53 may be a potential strategy to sensitize mutant p53 TNF-resistant tumors to the cytotoxic action of this cytokine.

Wild-type p53 induced sensitization of mutant p53 TNF-resistant cells: Role of caspase-8 and mitochondria

“…30 More recently, we have shown that adenovirus -based transfer of wtp53 gene increased sensitivity of cells with mutant p53 to the cytotoxic effect of TNF 31 by a mechanism independent of Bax and Bcl -2 expression but involving ROS production. 43 In the present study, we further examined the molecular basis of tumor resistance to the cytotoxic action of TNF and explored the wtp53-induced sensitization of TNF -resistant cells to the cytotoxic action of TNF.…”

“…31 Several reports indicate that p53 can induce or potentiate apoptosis through a variety of mechanisms, e.g., by regulating the expression of genes that participate in the apoptotic response at the mitochondrial level, 45,46 a transcription -dependent p53 -induced alteration in the redox balance, 47 and /or through transcription -independent effects, 28,48,49 which may involve the translocation of p53 to mitochondrial membranes, facilitating their permeabilization. 50 Caspase activation (caspases-3 and -9) has also been connected to p53 -mediated cell death.…”

“…31 Efficiency of Adwtp53 to transfer and direct expression of wtp53 was analysed on p53 -negative SAOS cells using specific monoclonal antibody 36 hours after infection with Adwtp53. The expression of functional p53 in Adwtp53-infected cells was then analysed using the p53 functional assay in yeast as described.…”

“…30 Moreover, we have demonstrated that the transfer of wtp53 using an adenoviral vector ( Adwtp53) reestablishes TNF sensitivity in TNF -resistant cells. 31 In the present study, we investigated the mechanisms of the p53 -mediated restoration of TNF sensitivity. It appears that the p53 effect involves the reestablishment of the TNF -mediated proapoptotic signal transduction cascade, including the activation of caspase -8 and mitochondrial membrane permeabilization.…”

Enhanced tumor cell kill by combined treatment with a small-molecule antagonist of mouse double minute 2 and adenoviruses encoding p53

“…The replication-deficient adenovirus vector Adwtp53 that harbors a human p53 gene driven by a SV40 virus early promoter in place of the E1 region has been described previously (19). The conditionally replicative adenovirus AdD24 that lacks 24 bp corresponding to amino acids 122 to 129 in the CR2 domain of E1A necessary for binding to Rb protein (20) and has a deleted E3 region and its derivative AdD24-p53 that carries a SV40 virus early-p53 expression cassette inserted in place of the deleted E3 region were described before (17).…”