Effect of a two-base insertion mutation of thegene on expression of p53 protein in canine histiocytic sarcoma cells.

Abstract

OBJECTIVE: To examine effects of a common mutation (2-base insertion in exon 5) of thegene on biological function of p53 protein in canine histiocytic sarcoma cells. SAMPLE: Canine histiocytic tumor cell lines DH82 with deletion ofand CHS-3 with the wild-typeand canine wild-type and mutantfragments. PROCEDURES: Wild-type or mutantwith a polyprotein peptide tag at the N-terminus was transduced into DH82 and CHS-3 cells. Expression of p53 protein, changes in function as a transcription factor, and susceptibility to doxorubicin and nimustine were compared. RESULTS: Transduced p53 protein was detected in wild-type-transduced DH82 and CHS-3 cells, whereas expression was not detected in mutant-transduced cells. There were significant increases in expression of target genes of p53 protein, includingand, in wild-type-transduced cells, compared with results for native and mock-transfected cells, but not in mutant-transduced cells. There was no significant difference in drug susceptibilities among native and derivative cells of CHS-3. However, cell viabilities of wild-type-transduced DH82 cells incubated with doxorubicin were significantly lower than viabilities of native, mock-transfected, and AT insertion mutation--transduced DH82 cells; susceptibility to nimustine did not differ significantly among cells. CONCLUSIONS AND CLINICAL RELEVANCE: Expression of p53 protein and its function as a transcription factor were lost after addition of a 2-base insertion in thegene in canine histiocytic tumor cells. Additional studies are needed to investigate the clinical relevance of this mutation in histiocytic sarcomas of dogs.