Nestin, a class VI intermediate filament
protein, is known to be expressed in various types of human
neoplasms, including
breast cancer, and is associated with their progression. However, its expression and role in canine mammary
tumors remain unknown. We analyzed
nestin expression in canine mammary
tumors using in situ hybridization and immunohistochemistry. We also investigated its role in a canine mammary
carcinoma cell line using RNA interference.
Nestin expression was not observed in
luminal epithelial cells of any of the 62 cases of benign mammary lesions examined, although myoepithelial cells showed its expression in most cases. In 16/50 (32%) primary mammary
carcinomas and 6/15 (40%)
metastases of mammary
carcinomas, cytoplasmic
nestin expression was detected in
luminal epithelial cells. In
luminal cells of primary mammary
carcinomas, its expression was positively related to several pathological parameters that indicate high-grade
malignancy, including histological grading (P < .01), vascular/lymphatic invasion (P < .01), Ki-67 index (P < .01), and
metastasis (P < .05). Immunohistochemistry revealed that
nestin expression was related to
vimentin expression in mammary
carcinomas (P < .01). This relationship was confirmed using reverse transcription-quantitative polymerase chain reaction using 9 cell lines derived from canine mammary
carcinoma (P < .01). Finally,
nestin knockdown in canine mammary
carcinoma cells using
small interfering RNA inhibited cell proliferation and migration based on
WST-8, Boyden chamber, and cell-tracking assays. These findings suggest that
nestin may at least partially mediate these behaviors of canine mammary
carcinoma cells.