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Mammary Stem Cells and Tumor-Initiating Cells Are More Resistant to Apoptosis and Exhibit Increased DNA Repair Activity in Response to DNA Damage.

ABSTRACT: Adult stem cells and tumor-initiating cells (TICs) often employ different mechanisms of DNA damage response (DDR) as compared to other tissue cell types. However, little is known about how mammary stem cells (MaSCs) and mammary TICs respond to DNA damage. Using the mouse mammary gland and syngeneic p53-null tumors as models, we investigated the molecular and physiological consequences of DNA damage in wild-type MaSCs, p53-null MaSCs, and p53-null TICs. We showed that wild-type MaSCs and basal cells are more resistant to apoptosis and exhibit increased non-homologous end joining (NHEJ) activity. Loss of p53 in mammary epithelium affected both cell-cycle regulation and DNA repair efficiency. In p53-null tumors, we showed that TICs are more resistant to ionizing radiation (IR) due to decreased apoptosis, elevated NHEJ activity, and more-rapid DNA repair. These results have important implications for understanding DDR mechanisms involved in both tumorigenesis and therapy resistance.

SUBMITTER: Chang CH

PROVIDER: S-EPMC4618454 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature

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Mammary Stem Cells and Tumor-Initiating Cells Are More Resistant to Apoptosis and Exhibit Increased DNA Repair Activity in Response to DNA Damage.

Chang Chi-Hsuan CH Zhang Mei M Rajapakshe Kimal K Coarfa Cristian C Edwards Dean D Huang Shixia S Rosen Jeffrey M JM

Stem cell reports 20150820 3

Adult stem cells and tumor-initiating cells (TICs) often employ different mechanisms of DNA damage response (DDR) as compared to other tissue cell types. However, little is known about how mammary stem cells (MaSCs) and mammary TICs respond to DNA damage. Using the mouse mammary gland and syngeneic p53-null tumors as models, we investigated the molecular and physiological consequences of DNA damage in wild-type MaSCs, p53-null MaSCs, and p53-null TICs. We showed that wild-type MaSCs and basal ce ...[more]

PMID: 26300228

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Project description:BackgroundCancer-initiating cells (CICs) are proposed to be responsible for the generation of metastasis and resistance to therapy. Accumulating evidences indicates CICs are found among different human cancers and cell lines derived from them. Few studies address the characteristics of CICs in cervical cancer. We identify biological features of CICs from four of the best-know human cell lines from uterine cervix tumors. (HeLa, SiHa, Ca Ski, C-4 I).MethodsCells were cultured as spheres under stem-cell conditions. Flow cytometry was used to detect expression of CD34, CD49f and CD133 antigens and Hoechst 33342 staining to identify side population (SP). Magnetic and fluorescence-activated cell sorting was applied to enrich and purify populations used to evaluate tumorigenicity in nude mice. cDNA microarray analysis and in vitro radioresistance assay were carried out under standard conditions.ResultsCICs, enriched as spheroids, were capable to generate reproducible tumor phenotypes in nu-nu mice and serial propagation. Injection of 1 × 10³ dissociated spheroid cells induced tumors in the majority of animals, whereas injection of 1 × 10⁵ monolayer cells remained nontumorigenic. Sphere-derived CICs expressed CD49f surface marker. Gene profiling analysis of HeLa and SiHa spheroid cells showed up-regulation of CICs markers characteristic of the female reproductive system. Importantly, epithelial to mesenchymal (EMT) transition-associated markers were found highly expressed in spheroid cells. More importantly, gene expression analysis indicated that genes required for radioresistance were also up-regulated, including components of the double-strand break (DSB) DNA repair machinery and the metabolism of reactive oxygen species (ROS). Dose-dependent radiation assay indicated indeed that CICs-enriched populations exhibit an increased resistance to ionizing radiation (IR).ConclusionsWe characterized a self-renewing subpopulation of CICs found among four well known human cancer-derived cell lines (HeLa, SiHa, Ca Ski and C-4 I) and found that they express characteristic markers of stem cell, EMT and radioresistance. The fact that CICs demonstrated a higher degree of resistance to radiation than differentiated cells suggests that specific detection and targeting of CICs could be highly valuable for the therapy of tumors from the uterine cervix.

Dataset Information

Mammary Stem Cells and Tumor-Initiating Cells Are More Resistant to Apoptosis and Exhibit Increased DNA Repair Activity in Response to DNA Damage.

Publications

Mammary Stem Cells and Tumor-Initiating Cells Are More Resistant to Apoptosis and Exhibit Increased DNA Repair Activity in Response to DNA Damage.

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