Differential gene expression of naturally occurring malignant and benign canine mammary tumors

Abstract

Cancer in companion animals is one of the leading causes of non-accidental death. Understanding the gene expression profile in tumors can help to develop effective treatments and interventions to prolong and improve the life of companion animals with cancer. In this study gene expression of naturally occurring mammary tumors, 46 complex adenomas (benign) and 19 adenocarcinomas (malignant), collected from female dogs were compared. The mammary tumors were removed as part of normal health care by standard surgical procedures from female beagles aged between 5 and 15 years. The center part of the tumor was snap frozen in liquid nitrogen. RNA was isolated from the tumor tissues and applied to Affymetrix GeneChip® Canine Genome 2.0 Array. We found that 302 genes were differentially expressed. In the malignant mammary tumors, 149 genes were up-regulated and 153 genes were down-regulated compared to the benign tumors. Genes associated with cell cycle regulation, cell division, and cell remodeling were affected. Based on these findings it can be concluded that malignant tumors have a more active cell division machinery compared to benign tumors.