Simultaneous Inactivation of the p16, p15 and p14 Genes Encoding Cyclin-Dependent Kinase Inhibitors in Canine T-Lymphoid Tumor Cells

Aki FUJIWARA-IGARASHI, Yuko GOTO-KOSHINO, Hiroyuki MOCHIZUKI, Shingo MAEDA, Yasuhito FUJINO, Koichi OHNO, Hajime TSUJIMOTO

The p16, p15 and p14 genes are widely known as tumor suppressor genes in human medicine. Although a large number of genetic and epigenetic aberrations in these genes have been reported in human malignancies, canine malignancies have not been well analyzed on the aberrations of these genes. In this study, the full-length complementary DNA (cDNA) of the canine p16 gene was cloned using the 5' and 3' rapid amplification of cDNA ends methods. Based on the sequence data, primers specific for p16, p15 and p14 were designed. Using these primers, the expression of p16, p15 and p14 mRNAs could be individually evaluated by reverse transcriptase polymerase chain reaction. Genomic aberrations were also examined using genomic polymerase chain reaction. Two of the 6 canine lymphoid tumor cell lines did not express detectable levels of p16, p15 and p14 mRNAs, and wide-ranging deletions in the p15-p14-p16 genomic locus were suspected. Wide-ranging deletions were also speculated in 2 of 14 dogs with T-cell lymphoid tumors. On the other hand, similar failure of amplification suggesting wide-ranging deletions were not observed in any of the 14 dogs with B-cell lymphoma. Deletion of the p15-p14-p16 genomic locus could be one of the molecular aberrations in canine lymphoid tumor cells.