Human lymphoblastoid cell lines expressing mutant p53 exhibit decreased sensitivity to cisplatin-induced cytotoxicity

Abstract

Human lymphoblastoid cells were transfected with expression vectors containing p53 cDNA mutated at either codon 135 or 246. The cells were subjected to cisplatin treatment or g-radiation and observed for changes in the cell cycle arrest and apoptosis. We found that compared to the parental cell line, cells overexpressing mutant p53 (either 246 val or 135 ser ) exhibited decreased apoptosis in response to g-radiation or cisplatin as measured by: propidium iodide (PI) staining of the cellular DNA (cell cycle analysis) and decrease in PARP (poly ADP-ribose polymerase) cleavage as detected by Western blotting. Interestingly the cells expressing mutant p53(135 ser ) protein were less resistant to cisplatin-induced apoptosis than the p53(246 val )-bearing cell line. A signi®cant decrease in the G1/S arrest assayed by bromodeoxyuridine and PI staining (cell cycle/proliferation assay) was also observed in response to irradiation and cisplatin in cell lines expressing either of the mutant p53 constructs. A lower basal level and reduced magnitude of protein induction of the cell cycle inhibitor p21/Waf1 was seen both after cisplatin and g-radiation treatment in the mutant p53 expressing lymphoblastoid variant when compared to the wild type p53 parental cell line but induction of the p53 regulator MDM2 was comparable in both. No increase in basal levels of Bc12 protein in wild type or mutant p53 expressing cells was observed in response to cisplatin or irradiation. Unexpectedly, following cisplatin treatment we observed an increase in mutant and wild type p53 RNA steady state levels in addition to increased levels of p53 protein. These results suggest that irradiation or cisplatin treatment may not only stabilize wild type p53 protein but also may increase the steady state p53 RNA levels. Finally these results indicate that both irradiation and cisplatin should be used with caution in the treatment of lymphoid tumors bearing mutations of p53.

Overexpression of Protein Kinase Cδ Enhances Cisplatin-Induced Cytotoxicity Correlated with p53 in Gastric Cancer Cell Line

“…It has been widely demonstrated that cancer cells expressing mutated p53 are associated with an increased resistance to cisplatin and that expression of wt-p53 in these cells increased the cytotoxicity of cisplatin [21][22][23][24]. The present result shows that infection of Ad-PKC‰ alone could not induce MKN28 cell death effectively because a mutated form of p53 protein in MKN28 possibly plays a role as a dominant negative form [25]. Moreover, several other signaling components, e.g.…”

Comparative analysis of the mutagenic activity of oxaliplatin and cisplatin in the Hprt gene of CHO cells

“…Among the main factors influencing cell sensitivity to cisplatin and oxaliplatin, those affecting the p53-dependent apoptotic pathway seem to be relevant [Gallagher et al, 1997;Piovesan et al, 1998;Manic et al, 2003]. Since CHO-K1 cells have a nonfunctional p53 protein [Hu et al, 1999], the tolerance of CHO-K1 cells to oxaliplatin may be related to an impairment of p53-mediated apoptosis.…”

The consequence of p53 overexpression for liver tumor development and the response of transformed murine hepatocytes to genotoxic agents

“…Inactivation of p53 contributes not only to tumor progression but also to resistance of cancer cells to chemotherapy (Fan et al, 1994;Goto et al, 1998;Piovesan et al, 1998), although certain exceptions have been described (Gudas et al, 1996). Moreover, restoration of wt p53 in cells lacking or expressing mutated p53 can enhance apoptosis induced by DNAdamaging agents or chemotherapy (Blagosklonny and El Deiry, 1998;Fujiwara et al, 1994;Gurnani et al, 1999;Ju et al, 1998;Seth et al, 1997;Song et al, 1997).…”