The significance of p53 and retinoblastoma pathways in canine hemangiosarcoma.
To investigate whether inactivation of the p53 and retinoblastoma (Rb) protein pathways contributes to the development of canine hemangiosarcoma (HSA), we examined immunohistochemically the expression of p53, Rb, phosphorylated Rb (phospho-Rb), p16, and cyclin D1 in 39 spontaneous canine HSAs and 10 hemangiomas. In addition, mutations in the p53 gene were analyzed by polymerase chain reaction (PCR)-single-stranded conformation polymorphism and PCR direct sequencing; furthermore, we quantified cyclin D1 mRNA by semiquantitative real-time reverse transcription-PCR. Positive immunoreactivity for p53 was observed in 17.9% of HSAs. However, mutations were not detected in these cases. The labeling indices for Rb, phospho-Rb, and cyclin D1 were markedly higher in all HSAs than in hemangiomas. Of the 7 cases with cyclin D1-positive immunoreactivity, 4 overexpressed cyclin D1 mRNA (to a level more than 10-fold higher than that of GAPDH mRNA). The p16 protein was clearly detected in all hemangiomas; however, 82% of the neoplastic cells in HSA showed a loss of or low immunoreactivity. These results suggest that alteration of the p16-cyclin D1-Rb pathway, rather than the p53 pathway, may be associated with the pathogenesis of canine HSA.
Yonemaru
Kayoko
K
Laboratoriy of Veterinary Pathology, Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, Japan.
Sakai
Hiroki
H
Murakami
Mami
M
Kodama
Atsushi
A
Mori
Takashi
T
Yanai
Tokuma
T
Maruo
Kohji
K
Masegi
Toshiaki
T
D000818:Animals; D001483:Base Sequence; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism; D017931:DNA Primers; D004283:Dog Diseases / Q000378:metabolism*; D004285:Dogs; D006394:Hemangiosarcoma / Q000378:metabolism / Q000662:veterinary*; D007150:Immunohistochemistry / Q000662:veterinary; D008969:Molecular Sequence Data; D018807:Polymorphism, Single-Stranded Conformational; D016160:Retinoblastoma Protein / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D017422:Sequence Analysis, DNA / Q000662:veterinary; D015398:Signal Transduction / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
D019941:Cyclin-Dependent Kinase Inhibitor p16; D017931:DNA Primers; D016160:Retinoblastoma Protein; D016159:Tumor Suppressor Protein p53; D019938:Cyclin D1