Expression changes and significance of BLM and RecQ4 helicases in breast cancer stem cells

LU Yuan; GE Zhangwen; LIU Jielin

doi:10.3969/j.issn.1002-266X.2017.04.003

Abstract：Objective To investigate the expression changes of BLM and RecQ 4 helicases in breast cancer stem cells . Methods Breast cancer stem cells were screened from breast cancer MDA-MB-435 cells and were cultured in serum-free medium.The tumorigenicity of breast cancer stem cells and MDA-MB-435 cells was observed by tumor formation in nude mice.The drug resistance gene ATP-binding cassette transporter G 2 ( ABCG2) mRNA of stem cells was detected by RT-PCR.The protein expression of BLM and RecQ 4 was detected in breast cancer MDA-MB-435 cells and their stem cells by Western Blotting and fluorescent staining .Results The proportion of surface markers CD 44 +CD24 -/low in cancer stem cells was significantly higher , but the proportion of membrane surface CD 44 +CD24 +was significantly lower than that of MDA-MB-435 cells ( all P <0.05).No statistical significance was found in the proportions of cell membrane surface CD44 -CD24 +and CD44 -CD24-between these two kinds of cells (all P<0.05).The mRNA expression of ABCG2 was 0.753 ±0.025 in stem cells, and it was 0.563 ±0.112 in the breast cancer MDA-MB-435 cells (P<0.05).Compared with the nude mice inoculated with the same density of MDA-MB-435 cells, the nude mice inoculated with stem cells had an early tumor formation time and a large tumor volume .The BLM protein expression of stem cells was lower and RecQ 4 protein expression was higher than that of MDA-MB-435 cells (all P<0.05).Conclusion The tumorigenicity is high in breast cancer stem cells , which may be associated with low expression of BLM and high expression of RecQ 4 in breast canc-er stem cells.