Identification of molecular genetic contributants to canine cutaneous mast cell tumour metastasis by global gene expression analysis

Abstract

Cutaneous mast cell tumours are one of the most common canine cancers. Approximately 25% of the tumours metastasise. Activating c-kit mutations are present in about 20% of tumours, but metastases occur in the absence of mutations. Tumour metastasis is associated with significantly diminished survival in spite of adjuvant chemotherapy. Available prognostic tests do not reliably predict whether a tumour will metastasise. In this study we compared the global expression profiles of 20 primary cutaneous mast cell tumours that metastasised with those of 20 primary tumours that did not metastasise. The objective was to identify genes associated with mast cell tumour metastatic progression that may represent targets for therapeutic intervention and biomarkers for prediction of tumour metastasis. Canine Gene 1.1 ST Arrays were employed for genome-wide expression analysis of formalin-fixed, paraffin-embedded biopsies of mast cell tumours borne by dogs that either died due to confirmed mast cell tumour metastasis, or were still alive more than 1000 days post-surgery. Decreased gene expression in the metastasising tumours appears to be associated with a loss of cell polarity, reduced cell-cell and cell-ECM adhesion, and increased cell deformability and motility. Dysregulated gene expression may also promote extracellular matrix and base membrane degradation, suppression of cell cycle arrest and apoptosis, and angiogenesis. Down-regulation of gene expression in the metastasising tumours may be achieved at least in part by small nucleolar RNA-derived RNA and microRNA-effected gene silencing. Employing cross-validation, a linear discriminant analysis-based classifier featuring 19 genes that displayed two-fold differences in expression between metastasising and non-metastasising tumours was estimated to classify metastasising and non-metastasising tumours with accuracies of 90–100% and 70–100%, respectively. The differential expression of 9 of the discriminator genes was confirmed by quantitative reverse transcription-PCR.

miRNA profiles of canine cutaneous mast cell tumours with early nodal metastasis and evaluation as potential biomarkers

“…Gene Ontology and KEGG pathway analysis suggested that DE-miRNAs have an impact on transcription activities, cell cycle progression and cell survival and, in general, on several pathways involved in cancer development. This hypothesis is supported by gene expression analysis of canine cutaneous MCTs 10 , 48 . Gene expression profiling of metastatic and non-metastatic MCTs using an array approach identified differentially expressed genes involved in apoptosis, cell cycle arrest and loss of cell polarity and adhesion 48 .…”

Molecular Mechanisms of Canine Cancers

“…Mast cell tumors are usually categorized according to histologic grade. Two grading systems currently exist: the Patnaik system, which assigns a grade according to the degree of differentiation of the tumor, where "I" is well-differentiated, "II" is intermediately-differentiated, and "III" is poorly-differentiated, and the Kiupel system, which categorizes a tumor as low or high grade according to survival time [45]. However, neither system predicts metastasis.…”

“…Although c-KIT mutations seem to be the primary contributor to mast cell tumors, other genes have been observed to contribute to a more severe prognosis and shorter survival times. Specific gene losses in PTEN, FAS, and CFA26 and gene gains in MAPK3, WNT5B, FGF, FOXM1, RAD51 and CFA27 are several potential candidate genes that can be examined for their effects on mast cell tumorigenesis [45,53].…”

Companion canines: an under-utilised model to aid in translating anti-metastatics to the clinic

“…The demonstration that gene expression signatures of metastatic potential could be detected in primary human tumours [12] lead to the identification of metastasis-associated gene expression signatures by comparison of gene expression in human primary tumours that did and did not metastasise [13,14]. Veterinary researchers have performed similar comparisons of metastasising and non-metastasising primary tumours to identify molecular genetic and epigenetic events associated with canine tumour metastasis, both as targets for anti-metastatic therapeutics and potential prognostic biomarkers [15][16][17][18][19]. Such studies will expedite the identification of potential targets for drugs aimed at preventing human tumour metastasis by strengthening the 'candidature', as a target, of genes that are associated with the metastasis of a given tumour in both humans and dogs.…”