Background and purpose: Human epidermal growth factor receptor 2 (HER-2) is the member of tyrosine kinase receptor family. Its differential expression plays the key role in choosing targeted drug for breast cancer. This study focused on screening the breast cancer cell clones of different HER-2 expression levels

and studying the biological characteristics of these cells. Methods: Breast cancer SK-BR-3 cells were clonally purified

and the expression level of soluble HER-2 (sHER-2) from the culture supernatant was detected by the ECLIA on ADVIA Centaur CP System. Cell clones with high expression (50.0 ng/mL)

medium expression (15.8-50.0 ng/mL) and low expression (15.8 ng/mL) of sHER-2 were identified

respectively. This study observed the morphological changes of cell strains with differential expression levels of sHER-2 by cell culture. Besides

biological characteristics were compared by a series of experiments in vitro

such as clone formation

scratch assay

and transwell detection. Results: Compared with normal breast cells

sHER-2 was overexpressed significantly in SK-BR-3 breast cancer cells. Furthermore

the abilities of clone formation

mobility and invasion of sHER-2 high expression cell strain [(51.3±3.4)%

(50.0±0.6)% and (53.5±4.2)%] were significantly higher than those of sHER-2 medium expression [(42.0±3.7)%

(19.5±3.4)% and (33.2±3.9)%] or sHER-2 low expression [(26.7±2.9)%

(13.6±1.0)% and (28.9±5.4)%]

and the differences were all statistically significant (P0.05). Conclusion: Breast cancer cell strain with high expression level of sHER-2 can enhance cell proliferation

promote cell motility and other biological effects

which may lay the foundation for clinical screening of targeted drug therapies for breast cancer.