Section of Pharmacology, Dept. of Internal Medicine Di.M.I., and Center of Excellence for Biomedical Research - University of Genova, Viale Benedetto XV, 2, 16132 Genova, Italy.
Exp Cell Res. 2012 Apr 15;318(7):847-60. doi: 10.1016/j.yexcr.2012.02.008. Epub 2012 Feb 16.
Current carcinogenesis theory states that only a small subset of tumor cells, the cancer stem cells or tumor initiating cells (TICs), are responsible for tumor formation and progression. Human breast cancer-initiating cells have been identified as CD44-expressing cells, which retain tumorigenic activity and display stem cell-like properties. Spontaneous feline mammary carcinoma (FMC) is an aggressive cancer, which shows biological similarities to the human tumor counterpart. We report the isolation and phenotypic characterization of FMC-derived stem/progenitor cells, showing in vitro self-renewal, long-lasting proliferation and in vivo tumorigenicity. Twenty-one FMC samples were collected, histologically classified and characterized for the expression of Ki67, EGFR, ER-α and CD44, by immunohistochemistry. By culture in stem cell permissive conditions, we isolated, from 13 FMCs, a CD44-positive subpopulation able to survive and proliferate in vitro as mammospheres of different sizes and morphologies. When injected in NOD/SCID mice, FMC stem-like cells initiate tumors, generating cell heterogeneity and recapitulating the original histotype. In serum-containing medium, spheroid cells showed differentiation properties as shown by morphological changes, the loss of CD44 expression and tumorigenic potential. These data show that stem-defined culture of FMC enriches for TICs and validate the use of these cells as a suitable model for comparative oncology studies of mammary biology and testing therapeutic strategies aimed at eradicating TICs.
目前的癌变理论认为，只有一小部分肿瘤细胞，即癌症干细胞或肿瘤起始细胞（TICs），负责肿瘤的形成和进展。人类乳腺癌起始细胞已被鉴定为表达 CD44 的细胞，这些细胞保留了致瘤活性，并表现出干细胞样特性。自发性猫乳腺肿瘤（FMC）是一种侵袭性癌症，其具有与人类肿瘤相对应的生物学相似性。我们报告了 FMC 衍生的干细胞/祖细胞的分离和表型特征，这些细胞表现出体外自我更新、长期增殖和体内致瘤性。收集了 21 个 FMC 样本，通过免疫组织化学方法对 Ki67、EGFR、ER-α 和 CD44 的表达进行了组织学分类和特征分析。通过在干细胞允许的条件下培养，我们从 13 个 FMC 中分离出一个 CD44 阳性亚群，该亚群能够在体外作为不同大小和形态的乳腺球体存活和增殖。当将 FMC 类干细胞注入 NOD/SCID 小鼠中时，它们会引发肿瘤，产生细胞异质性并重现原始组织类型。在含血清的培养基中，球体细胞表现出分化特性，如形态变化、CD44 表达丧失和致瘤潜力降低。这些数据表明，FMC 的基于干细胞的培养方法富集了 TICs，并验证了使用这些细胞作为乳腺生物学比较肿瘤学研究和测试旨在消除 TICs 的治疗策略的合适模型。
