From Veterinary Pathology
In recent years, the use of Naked mole-rats (NMRs) as animal models in aging and cancer research has increased as a result of their demonstrated extreme longevity and apparent resistance to cancer. NMRs have a very low incidence of cancer when compared to laboratory rodents and other mammal species with similar life spans. Here, researchers report for the first time 2 cases of cancer in zoo-housed NMRs revealing for the first time that NMRs are capable of developing cancer. The study concludes that continued surveillance of zoo- and laboratory-housed NMRs will be prudent to better characterize health and naturally occurring disease states, including neoplasia, in this exquisitely adapted, unique species and valuable animal model.
Naked mole-rats (NMRs; Heterocephalus glaber) are highly adapted, eusocial rodents renowned for their extreme longevity and resistance to cancer. Because cancer has not been formally described in this species, NMRs have been increasingly utilized as an animal model in aging and cancer research. We previously reported the occurrence of several age-related diseases, including putative pre-neoplastic lesions, in zoo-housed NMR colonies. Here, we report for the first time 2 cases of cancer in zoo-housed NMRs. In Case No. 1, we observed a subcutaneous mass in the axillary region of a 22-year-old male NMR, with histologic, immunohistochemical (pancytokeratin positive, rare p63 immunolabeling, and smooth muscle actin negative), and ultrastructural characteristics of an adenocarcinoma possibly of mammary or salivary origin. In Case No. 2, we observed a densely cellular, poorly demarcated gastric mass of polygonal cells arranged in nests with positive immunolabeling for synaptophysin and chromogranin indicative of a neuroendocrine carcinoma in an approximately 20-year-old male NMR. We also include a brief discussion of other proliferative growths and pre-cancerous lesions diagnosed in 1 zoo colony. Although these case reports do not alter the longstanding observation of cancer resistance, they do raise questions about the scope of cancer resistance and the interpretation of biomedical studies in this model. These reports also highlight the benefit of long-term disease investigations in zoo-housed populations to better understand naturally occurring disease processes in species used as models in biomedical research.
A. Delaney, J. M. Ward, T. F. Walsh, S. K. Chinnadurai, K. Kerns, M. J. Kinsel, and P. M. Treuting
Initial Case Reports of Cancer in Naked Mole-rats (Heterocephalus glaber)
Vet Pathol 0300985816630796, first published on February 4, 2016 doi:10.1177/0300985816630796