Identify in Breast Cancer Stem Cell-Like Cells the Proteins Involved in Non- Homologous End Joining DNA Repair

Abstract

Abstract : In breast cancer stem-like cells could contribute not only to the initiation of the cancer but also to recurrence because of the resistance of stem cells to chemo/radiation therapy. From several breast cancer cell lines we have demonstrated the existence of breast cancer stem-like cell subpopulations based on the recognized cell surface markers CD44+/CD24 and ABCG2-mediated Hoechst effiux. After radiation we found that a CD44+/CD24-or low subpopulation showed increased clonogenic survival in MCF-7 and HCC1937 cell lines but not in the MDA-MB231 cell line. However examination of NHEJ activity and expressed proteins of NHEJ did not show any significant difference among the subpopulations suggesting that the increased radiation resistance might not be related to the NHEJ. Furthermore activation of ATM/ATR pathway was significantly different among the subpopulations of MCF-7, HCC1937 and MDA-MB-231 cell lines and these differences in the activation of ATM/ATR pathway may explain the differential radiation resistance of subpopulations.