Comprehensive Genomic Profiling of Androgen-Receptor-Negative Canine Prostate Cancer

Abstract

Canine carcinomas have been considered natural models for human diseases; however, the genomic profile of canine prostate cancers (PCs) has not been explored. In this study, 14 PC androgen-receptor-negative cases, 4 proliferative inflammatory atrophies (PIA), and 5 normal prostate tissues were investigated by array-based comparative genomic hybridization (aCGH). Copy number alterations (CNAs) were assessed using the Canine Genome CGH Microarray 4 × 44K (Agilent Technologies). Genes covered by recurrent CNAs were submitted to enrichment and cross-validation analysis. In addition, the expression levels of TP53, MDM2 and ZBTB4 were evaluated in an independent set of cases by qPCR. PC cases presented genomic complexity, while PIA samples had a small number of CNAs. Recurrent losses covering well-known tumor suppressor genes, such as ATM, BRCA1, CDH1, MEN1 and TP53, were found in PC. The in silico functional analysis showed several cancer-related genes associated with canonical pathways and interaction networks previously described in human PC. The MDM2, TP53, and ZBTB4 copy number alterations were translated into altered expression levels. A cross-validation analysis using The Cancer Genome Atlas (TCGA) database for human PC uncovered similarities between canine and human PCs. Androgen-receptor-negative canine PC is a complex disease characterized by high genomic instability, showing a set of genes with similar alterations to human cancer.

Keywords: comparative oncology; copy number alteration; dog; microarray; proliferative inflammatory atrophy; prostate cancer.

Figure 1

Representative copy number alterations (ideogram) showing gains (blue), and losses (red) in 4 proliferative inflammatory atrophies (PIAs) (A) and 14 canine prostate carcinomas (B).

Figure 2

(A) Graphic representation of the canonical pathway called the molecular mechanism of cancer. Two cancer-related molecular interaction networks are indicated: (B) network 2, and (C) network 6, both associated with cell death and survival, organismal injury and abnormalities. Genes involved in gains, and losses are depicted in red and green colors, respectively. Images generated with the Ingenuity Pathway Analysis (IPA) software.

Figure 3

Circos plot showing recurrent copy number alteration (CNA) regions in canine prostate cancers (PCs), and the corresponding human chromosomal regions. The outer circle depicts canine (grey bars), and human chromosomes (colored bars). Regions of gains (blue), and losses (red) are shown between the outer and inner circles, below grey bars. The colored links indicate the corresponding regions involved in CNAs in dogs and humans.

Figure 4

Relative expression (log scale) of TP53 (A), ZBTB4 (B), and MDM2 (C) genes in normal and PC tissues. Data are presented as mean ± SD (standard deviation).