Abstract
The mutations of TP53 gene are frequently observed in canine histiocytic sarcoma (HS). The objective of this study was to examine the distribution of tumor cells with TP53 gene mutations. Tumor tissues were divided into three or four regions and TP53 gene mutations were examined. TP53 gene mutations were detected only in parts of the HS tissues from six of the eight dogs, and the frequency of the mutant allele varied (0-65%) among the tumor regions. This study suggests that canine HS can exhibit intratumor heterogeneity. Further studies are needed to examine the clinical significance of the intratumor heterogeneity of TP53 gene mutations.