Characterization of HOX gene expression in canine mammary tumour cell lines from spontaneous tumours.

Spatial/temporal controls of development are regulated by the homeotic (HOX) gene complex and require integration with oncogenes and tumour suppressors regulating cell cycle exit. Spontaneously derived neoplastic canine mammary carcinoma cell models were investigated to determine if HOX expression profiles were associated with neoplasia as HOX genes promote neoplastic potential in human cancers. Comparative assessment of human and canine breast cancer expression profiles revealed remarkable similarity for all four paralogous HOX gene clusters and several unlinked HOX genes. Five canine HOX genes were overexpressed with expression profiles consistent with oncogene-like character (HOXA1, HOXA13, HOXD4, HOXD9 and SIX1) and three HOX genes with underexpressed profiles (HOXA11, HOXC8 and HOXC9) were also identified as was an apparent nonsense mutation in HOXC6. This data, as well as a comparative analysis of similar data from human breast cancers suggested expression of selected HOX genes in canine mammary carcinoma could be contributing to the neoplastic phenotype.

Landscape phage ligands for PC3 prostate carcinoma cells.

Tumor-specific cytotoxicity of drugs can be enhanced by targeting them to tumor receptors using tumor-specific ligands. Phage display technology with its high throughput capacity for the analysis of targeting ligands possessing specific binding properties represents a very attractive tool in the quest for molecular ligands. Also, current phage nanobiotechnology concepts allow the use of intact phage particles and isolated phage coat proteins per se as components of nanomedicines. Herein, we describe the use of two landscape phage libraries to obtain phage ligands against PC3 prostate carcinoma cells. Following a very stringent selection scheme, we were able to identify three phage ligands, bearing the fusion peptides, DTDSHVNL, DTPYDLTG and DVVYALSDD that demonstrated specificity and selectivity to PC3 cells based on target-association assays, microscopy and flow cytometry. The phage ligands and their fusion coat proteins can be used as navigating modules in both therapeutic and diagnostic approaches to prostate carcinoma.

Expression and sequence of canine SIRT2 and p53 genes in canine mammary tumour cells - effects on downstream targets Wip1 and p21/Cip1.

We have characterized gene dysfunction in a cellular model of spontaneous canine mammary cancer by investigating specific gene defects in SIRT2 and p53 genes for comparative studies among canine tumour-derived cell lines. These genes and their downstream targets are involved in regulating gene silencing, cell cycle progression and prevention of senescence and apoptosis. Canine SIR2 reverse transcriptase-polymerase chain reaction amplicons were most homologous to human SIRT2 and revealed detectable transcripts in all cell lines. Canine SIRT2 contained non-conserved amino acid substitutions, representing mutations or allelic differences and interspecies differences. Sequence differences between individuals in p53 and SIRT2 were found in two cell lines including a stop codon in p53 and substitutions of conserved cysteine residues in the Zn(2+)-binding motif in SIRT2. Mutations in SIRT2 were coincident with expression of the p53 modulator, Wip1; a failure to activate p21/Cip1 and extended G2/M phase. A third cell line appeared to function normally in these two pathways and likely possesses other defects in proliferation-control genes. This data identify potentially important defects in pathways regulated by p53 and SIRT2 that modulate cell proliferation and integrate development, apoptosis and proliferative lifespan. These genes offer promising therapeutic targets, contributing to the transformed/immortalized phenotype in spontaneous canine mammary cancer.