A novel mouse model of human breast cancer stem-like cells with high CD44+CD24-/lower phenotype metastasis to human bone.
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 x 10(5), 1 x 10(6) human breast cancer stem-like cells, and 1 x 10(6) parental MDA-MB-231 cells, respectively. A positive control group (D) without implantation of human bone was also injected with 1 x 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 x 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.
Ling
Li-jun
LJ
Department of General Surgery, First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, China.
Wang
Shui
S
Liu
Xiao-an
XA
Shen
En-chao
EC
Ding
Qiang
Q
Lu
Chao
C
Xu
Jian
J
Cao
Qin-hong
QH
Zhu
Hai-qing
HQ
Wang
Feng
F
D000818:Animals; D001859:Bone Neoplasms / Q000556:secondary*; D001943:Breast Neoplasms / Q000473:pathology*; D051927:CD24 Antigen / Q000032:analysis*; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D005260:Female; D017228:Hepatocyte Growth Factor / Q000494:pharmacology; D006801:Humans; D018960:Hyaluronan Receptors / Q000032:analysis*; D007150:Immunohistochemistry; D051379:Mice; D014411:Neoplastic Stem Cells / Q000473:pathology*; D053495:Osteopontin / Q000032:analysis; D010641:Phenotype; D019718:Receptors, CXCR4 / Q000032:analysis
D051927:CD24 Antigen; C497889:CD24 protein, human; C497483:CD44 protein, human; C527276:CXCR4 protein, human; D018960:Hyaluronan Receptors; D019718:Receptors, CXCR4; D053495:Osteopontin; D017228:Hepatocyte Growth Factor