Part one : The study of construction and drug reversion in MCF-7/MX cell linesObjective: To study Chrysin reverse the drug resistance in MCF-7/MX cell lines. Methods: To establish the MCF-7/MX cell line by stepwise selection in mitoxantrone .

Study the characteristics of MCF-7 cell lines and characterized the expression of BCRP by using Western blot analysis.

Investigate Effects of Chrysin on Mitoxantrone Cytotoxicity in MCF-7 cell line by using MTT way.

Results: The MCF-7/MX cell line can be constructed by stepwise selection in mitoxantrone. MCF-7 cells had no detectable BCRP expression , however, BCRP is clearly overexpressed in mitoxantrone-selected MCF-7/MX cells and gradually increase when mitoxantrone increase from 8nM to 100nM.After being induced by mitoxantrone,cell multiplication time of MCF-7/MX cells is 37.87hour and the multidrug resistance index increased to 38 fold but chrysin can reverse drug resistance.In the MCF-7/MX cells, chrysin dramatically lowered the IC50 value of mitoxantrone from 19.954±0.190μM to 1.851±0.02μM、0.62±0.217μM (P < 0.05),similar to the IC50 value in the MCF-7 cells .

In the presence of chrysin (2.5μM,5μM), the IC50 value of mitoxantrone in MCF-7 cells was not significantly changed .

Conclusions:

1、The MCF-7/MX cell line can be constructed by stepwise selection in mitoxantrone .

2、After being induced by mitoxantrone, MCF-7/MX cells is highly drug-resistant .

3、Chrysin can reverse drug resistance of MCF-7/MX cells by targeting BCRP.

Part Two : Chrysin influences breast cancer stem cell Subgroup in MCF-7/MX cell linesObjective:

To Investigate the influence of chrysin on CD44~+CD24~- cell in MCF-7/MX cell linesMethods: We used FACSC and Cell immunofluorescence to analyse the percentage of CD44~+ CD24~- cells in MCF-7 and MCF-7/MX cell lines.

Results: Nearly 95% cells of MCF-7/MX and MCF-7 cell is CD44~+CD24~+. The percentage of the CD44~+CD24~-cells in MCF-7/MX cells was was not significantly changed by only Chrysin treatment relative to the CD44~+CD24~-cells in untreated cells (P > 0.05).The percentage of the CD44~+CD24~-cells in MCF-7/MX cells was decreased by Chrysin and Mitoxantrone treatment relative to the CD44~+CD24~-cells found at 3.2% in untreated cells. In MCF-7/MX cells treated by Chrysin and Mitoxantrone, the CD44~+CD24~-cells population was 2.684±0.226%,1.907±0.179 %,1.414±0.112 % and 1.448±0.057% at 10-2μM、10-1μM、100μM、101μM Chrysin , respectively(P < 0.05). The same results could be Investigate by using Cell immunofluorescence.

Conclusions: MCF-7/MXcells are Sensitive to mitoxantrone fowllowing the chrysin treatment. The percentage of the CD44~+CD24~-cells in MCF-7/MX cells was not significantly changed by only Chrysin treatment,so the chrysin can only become chemotherapy sensitizer.