Isolation of Canine Mammary Cells With Stem Cell Properties and Tumour‐Initiating Potential

Abstract

Recent data suggest that mammary carcinogenesis may be driven by cancer stem cells (CSCs) derived from mutated adult stem cells, which have acquired aberrant cell self-renewal or by progenitor cells that have acquired the capacity for cell self-renewal. Spontaneous mammary cancers in cats and dogs are important models for the understanding of human breast cancer and may represent alternative species model systems that can significantly contribute to the study of human oncogenesis. With the goal of identifying markers for isolating human breast CSCs, we have generated a canine model system to isolate and characterize normal and CSCs from dog mammary gland. Insight into the hierarchical organization of canine tumours may contribute to the development of universal concepts in oncogenesis by CSCs. Cells with stem cell properties were isolated from normal and tumoural canine breast tissue and propagated as mammospheres and tumourspheres in long-term non-adherent culture conditions. We showed that cells obtained from spheres that display self-renewing properties, have multi-lineage differentiation potential, could generate complex branched tubular structures in vitro and form tumours in NOD/SCID mice. We analysed these cells for the expression of human stem and CSC markers and are currently investigating the tumour-initiating properties of these cells and the hierarchical organization of normal and neoplastic canine mammary tissue.

Stem/Progenitor Cells in Non-Lactating Versus Lactating Equine Mammary Gland

“…In the present study, the differentiation of mammosphere cells toward both luminal and myoepithelial cells was achieved using 1 culture medium. This is in contrast to a study on bovine MaSC where 2 different selective media were used [24], but in line with what has been previously reported for the differentiation of canine [18] and human MaSC [51]. Lastly, but interestingly, the equine mammosphere cells were capable of differentiating into adipocytes when cultured in adipocyteinducing selective media [35].…”

“…To characterize mammosphere cells immunophenotypically, the expression of several stem cell markers, previously used for the phenotypic characterization of MaSC in other species [18,19,24,[31][32][33][34], was evaluated by flow cytometry. Per series, 2 · 10 5 cells were used and labeled with the following primary Abs: mouse anti-human CD29-FITC IgG 1 (Southern Biotech; clone TDM29, 1:10), rat anti-mouse CD44-APC IgG 2b (BD; clone IM7, 1:20), rat anti-mouse CD49f IgG 2a (Novus Biologicals; clone GoH3, 1:10), and rabbit anti-human Ki67 IgG (Abcam; ab15580, 1:200).…”

“…Moreover, functional in vivo assays to detect MaSC activity are missing in these species, emphasizing the need for developing additional in vitro assays to better characterize these cells. Several reports describe the isolation and characterization of MaSC from mammary gland tissues of dogs, mostly to gain better insights into mammary tumorogenesis [18][19][20], a process that shares many features with human breast cancer [21][22][23]. In cattle, on the other hand, MaSC are being studied mainly to explore their potential to improve milk production efficiency [1,[24][25][26][27].…”

Canine mammary tumors contain cancer stem-like cells and form spheroids with an embryonic stem cell signature

“…The viral treatment even prevented tumor formation in mice (Eriksson, et al, 2007). Further, sphere formation is also described in canine mammary glands and tumors (Cocola, et al, 2009, Michishita, et al, 2006.…”

Mammary Stem Cell Research in Veterinary Science: An Update

“…Cocola et al were the first to report the isolation of normal MaSC and CSC from dog mammary gland tissues [67]. These cells were propagated as mammospheres and tumor spheres for three to five passages in nonadherent cultures.…”