Abstract
Activation of p53 is well known to induce apoptosis and cell growth arrest through the expression of downstream genes and to play an important role in the suppression of tumor growth. Mutated p53 (mp53) protein is defective in these functions due to conformational change of p53 protein. Our previous in vitro study using cultured human cancer cells showed that radiation treatment in the presence of a molecular chaperone, p53 C-terminal peptide (amino acid residues 361-382) is more effective for inducing p53-mediated apoptosis than radiation treatment alone or p53 C-terminal peptide treatment alone, especially in mp53 cancer cells. In this study, we examined effects of p53 C-terminal peptides on tumor growth in in vivo experiments. p53 C-terminal peptide treatment to tumors induced growth delay in mp53 tumors transplanted with H1299/mp53 cells but not in p53-null tumors transplanted with H1299/neo cells. Tumor growth delay by X-rays was enhanced by p53 C-terminal peptide in the mp53 tumors. These results showed that the growth inhibition of the tumors after the combination treatment may be due to the increased apoptosis or cell growth arrest of H1299/mp53 cells. p53 C-terminal peptide might be available for p53-targeted radio-cancer therapy in patients with mp53 tumors.
