C-terminal peptides of p53 molecules enhance radiation-induced apoptosis in human mutant p53 cancer cells.
We propose here a novel p53-targeting radio-cancer therapy using p53 C-terminal peptides for patients having mutated p53. Hoechst 33342 staining showed that X-ray irradiation alone efficiently induced apoptotic bodies in wild-type p53 (wt p53) human head and neck cancer cells transfected with a neo control vector (SAS/neo cells), but hardly induced apoptotic bodies in mutation-type p53 (m p53) cells transfected with a vector carrying the m p53 gene (SAS/m p53). In contrast, transfection of p53 C-terminal peptides (amino acid residues 361-382 or 353-374) via liposomes caused a remarkable increase of apoptotic bodies in X-ray-irradiated SAS/m p53 cells, but did not enhance apoptotic bodies in X-ray-irradiated SAS/neo cells. In immunocytochemical analysis, positively stained cells for active type caspase-3 were observed at high frequency after X-ray irradiation in the SAS/m p53 cells pre-treated with p53 C-terminal peptides. In SAS/neo cells, positively stained cells for active type caspase-3 were observed with X-ray irradiation alone. Furthermore, protein extracts from X-ray-irradiated SAS/m p53 cells showed higher DNA-binding activity of p53 to p53 consensus sequence when supplemented in vitro with p53 C-terminal peptides than extracts from non-irradiated SAS/m p53 cells. These results suggest that radiation treatment in the presence of p53 C-terminal peptides is more effective for inducing p53 -mediated apoptosis than radiation treatment alone or p53 C-terminal peptide treatment alone, especially in m p53 cancer cells. This novel tool for enhancement of apoptosis induction in m p53 cells might be useful for p53-targeted radio-cancer therapy.
Ohnishi
K
K
Departments of Biology, Nara Medical University, School of Medicine, 840 Shijo-cho, Kashihara, Nara 634-8521, Japan. tohnishi@nmu-gw.naramed-u.ac.jp
Inaba
H
H
Yasumoto
J
J
Yuki
K
K
Takahashi
A
A
Ohnishi
T
T
D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects*; D045744:Cell Line, Tumor; D016384:Consensus Sequence; D016158:Genes, p53 / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009369:Neoplasms / Q000473:pathology*; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000494:pharmacology*; D014965:X-Rays
D010446:Peptide Fragments; D016159:Tumor Suppressor Protein p53