摘要
Background A satisfactory animal model of breast cancer metastasizing to bone is unavailable. In this study, we used human breast cancer stem-like cells and human bone to build a novel “human-source” model of human breast cancer skeletal metastasis. Methods Human breast cancer stem-like cells, the CD44^＋/CD24^-/lower subpopulation, was separated and cultured. Before injection with the stem-like cells, mice were implanted with human bone in the right or left dorsal flanks. Animals in Groups A, B, and C were injected with 1×10^5, 1×10^6 human breast cancer stem-like cells, and 1×10^6 parental MDA-MB-231 cells, respectively. A positive control group （D） without implantation of human bone was also injected with 1×10^6 MDA-MB-231 cells. Immunohistochemistry was performed for determination of CD34, CD105, smooth muscle antibody, CD44, CD24, cytokine, CXC chemokine receptor-4 （CXCR4）, and osteopontin （OPN）. mRNA levels of CD44, CD24, CXCR4, and OPN in bone metastasis tissues were analyzed by real-time quantitative polymerase chain reaction （PCR）.Results Our results demonstrated that cells in implanted human bones of group B, which received 1×10^6 cancer stem-like cells, stained strongly positive for CD44, CXCR4, and OPN, whereas those of other groups showed no or minimum staining. Moreover, group B had the highest incidence of human bone metastasis （77.8%, P=0.0230） and no accompaniment of other tissue metastasis. The real-time PCR showed an increase of CD44, CXCR4, and OPN mRNA in metastatic bone tissues in group B compared with those of groups C and D, however the expression of CD24 mRNA in group B were the lowest. Conclusions In the novel “human source” model of breast cancer, breast cancer stem-like cells demonstrated a higher human bone-seeking ability. Its mechanism might be related to the higher expressions of CD44, CXCR4, and OPN, and the lower expression of CD24 in breast cancer stem-like cells.
Background A satisfactory animal model of breast cancer metastasizing to bone is unavailable. In this study, we used human breast cancer stem-like cells and human bone to build a novel “human-source” model of human breast cancer skeletal metastasis. Methods Human breast cancer stem-like cells, the CD44^＋/CD24^-/lower subpopulation, was separated and cultured. Before injection with the stem-like cells, mice were implanted with human bone in the right or left dorsal flanks. Animals in Groups A, B, and C were injected with 1×10^5, 1×10^6 human breast cancer stem-like cells, and 1×10^6 parental MDA-MB-231 cells, respectively. A positive control group （D） without implantation of human bone was also injected with 1×10^6 MDA-MB-231 cells. Immunohistochemistry was performed for determination of CD34, CD105, smooth muscle antibody, CD44, CD24, cytokine, CXC chemokine receptor-4 （CXCR4）, and osteopontin （OPN）. mRNA levels of CD44, CD24, CXCR4, and OPN in bone metastasis tissues were analyzed by real-time quantitative polymerase chain reaction （PCR）.Results Our results demonstrated that cells in implanted human bones of group B, which received 1×10^6 cancer stem-like cells, stained strongly positive for CD44, CXCR4, and OPN, whereas those of other groups showed no or minimum staining. Moreover, group B had the highest incidence of human bone metastasis （77.8%, P=0.0230） and no accompaniment of other tissue metastasis. The real-time PCR showed an increase of CD44, CXCR4, and OPN mRNA in metastatic bone tissues in group B compared with those of groups C and D, however the expression of CD24 mRNA in group B were the lowest. Conclusions In the novel “human source” model of breast cancer, breast cancer stem-like cells demonstrated a higher human bone-seeking ability. Its mechanism might be related to the higher expressions of CD44, CXCR4, and OPN, and the lower expression of CD24 in breast cancer stem-like cells.
基金
This work was supported by grants from National Natural Science Foundation of China （No. 300740076）, Jiangsu Six Kinds of Outstanding Talents Foundation （No. 2006B070）, Jiangsu Science and Education for Health Foundation （No. RC2007054） and Jiangsu Province Post-doctor Foundation （No. 0601048B）.
