STAT3 mediates resistance of CD44+CD24−/low breast cancer stem cells to tamoxifen in vitro

Publication date: September 2012 Source:Journal of Biomedical Research, Volume 26, Issue 5 Author(s): Xiaoyan Wang , Guozhu Wang , Yi Zhao , Xiaoan Liu , Qiang Ding , Jingping Shi , Yin Ding , Shui Wang We sought to determine whether STAT3 mediated tamoxifen resistance of breast cancer stem cells in vitro. The capacities for mammosphere formation and STAT3 expression of CD44+CD24−/low MCF-7 and MCF-7 were observed. The CD44+CD24−/low subpopulation ratio and its sensitivity to adriamycin were analyzed in MCF-7 and TAM resistant (TAM-R) cells. Cell cycle, apoptosis, STAT3 and phospho-STAT3 changes were observed af-ter treatment with tamoxifen. Small interference RNA-mediated knockdown of STAT3 in TAM-R cells was also performed. CD44+CD24−/low MCF-7 showed higher capacities for mammosphere formation and STAT3 expression than total MCF-7. The CD44+CD24−/low subpopulation was also upregulated in TAM-R cells with less sensitivity to adriamycin than MCF-7. Cell cycle changes, anti-apoptotic effects and STAT3 changes were also found. Mean-while, the knock-down of STAT3 in TAM-R resulted in an increase in sensitivity to tamoxifen. It is concluded that STAT3 plays an essential role in breast cancer stem cells, which correlated with tamoxifen resistance.
Source: Journal of Biomedical Research - Category: Biochemistry Source Type: research