DNA Damage Response/Repair in Cancer Stem Cells - Potential vs. Controversies.

The existence of ‘cancer stem cells’ (CSCs) has been a topic of heated debate for the last few years within the field of cancer biology. Their continuous characterization in a variety of solid tumors has lead to an abundance of evidence supporting their existence. CSCs are believed to be responsible for resistance against conventional treatment regimes of chemotherapy and radiation, ultimately, leading to metastasis and patient demise. To help aid clinicians, pharmaceutical companies and academic labs investigating how to better kill these highly aggressive cells we have summarized the DNA repair mechanism(s) and their role in the maintenance and regulation of both normal and cancer stem cells. Our book represents a comprehensive investigation into the highly effective DNA repair mechanisms of CSCs and what we need to understand in order to develop more advanced therapies to eradicate them from patients. Currently, there are no other published works entirely on DNA repair and Cancer Stem Cells. In addition, our book provides a comprehensive overview of CSC isolation and characterization from a variety of solid tumor types.

For this eBook, and the associated Research Topic in Frontiers in Genetics, entitled: ‘Cancer-associated defects in the DNA damage response: drivers for malignant transformation and potential therapeutic targets’ we have selected 10 papers that each discusses important, yet distinct aspects of the response to DNA damage in normal cells and cancer cells. Using an evolutionary conserved signaling network called the ‘DNA damage response (DDR)’ cells maintain the integrity of their genome, and thus safeguard cellular functioning and the ability to create viably progeny. Initially, the DDR appeared to consist of few linear kinase-driven pathways. However, research over the past decades in model organisms, as well as in the human system has revealed that the DDR is a complex signaling network, wired by multiple parallel pathways and displaying extensive crosstalk. Besides phosphorylation, multiple other post-translational modifications, including ubiquitination and sumoylation, are involved to achieve chromatin remodeling and initiation of DNA repair. Also, rather than being a cell-intrinsic phenomenon, we increasingly appreciate that cell-cell communication is involved. The recognition and repair of DNA damage is essential to maintain normal physiology. Multiple pathological conditions have been attributed to defective DNA repair, most notably accelerated aging, neurodegeneration and cancer. In the context of cancer, through repair of DNA damage or elimination of irreparably damaged cells, the DDR clearly has a tumor-suppressive role. Indeed, many tumor cells show partially inactivated DDR signaling, which allows proliferation in the context of DNA damage-inducing oncogenes. Simultaneously, loss of specific DDR signaling nodes creates a specific dependence of tumor cells on their remaining DDR components, and thus creates therapeutic opportunities. Especially in the context of cancer treatment, numerous targeted agents are under investigation, either to potentiate the cytotoxic effects of chemo-radiotherapy, or to induce synthetic lethality with cancer-specific alterations, with the treatment of BRCA1/2 mutant cancers with PARP1 inhibitors as a prototype example. We have selected four review articles that provide insight into the key components and the wiring of the DDR and DNA repair. Torgovnick and Schumacher review the involvement of DNA repair in the initiation and treatment of cancer, Brinkmann et al., describe the involvement of ubiquitination in DNA damage signaling and Jaiswal and Lindqvist discuss how cell-extrinsic signaling participates in communication of DNA damage to neighboring cells. In addition, Shatneyeva and colleagues review the connection between the cellular response to DNA damage and escape from immune surveillance. Concerning the therapeutic application of targeting the DDR and DNA repair, three articles were included. Krajewska and van Vugt review the wiring of homologous recombination and how this offers therapeutic opportunities. Additionally, Knittel and colleagues describe how genetic loss of the central DDR component ATM in chronic lymphocytic leukemia can be exploited therapeutically by targeting certain parallel DNA repair pathways. Syljuasen and colleagues report on how targeting of the DDR can be used as a therapeutic strategy in lung cancer. Finally, three chapters describe newly identified regulators of the cellular response to DNA damage. Von Morgen et al. describe the R2TP complex, Lezzi and Fanciluuli review the involvement of Che-1/AATF in the DDR, and Ohms and co-authors describe how retrotransposons are at the basis of increased genomic instability. Altogether, these articles describe how defective responses to DNA damage underlie disease - and especially in the context of cancer -can be exploited to better treat disease.

Topic Editor Christian Reinhardt has received funding from companies Gilead, and lecture fees from Abbvie, Merck, and AstraZeneca. All other topic editors declare no competing interests with regards to the Research Topic subject.

DNA repair is a rapidly advancing field in biology and these systems represent a major defense mechanism against environmental and intracellular damaging agents such as sunlight, ionizing radiation, and reactive oxygen species. With contributions from eminent researchers, this book explores the basics and current trends in this critical field. Topics include carcinogenesis as a predictive and/or prognostic biomarker for cancer therapy, nucleotide excision repair, and tumor genetics and personalized medicine. The contributions provide essential information to scientists, pharmaceutical investigators, and clinicians interested in cancer therapy.

For this eBook, and the associated Research Topic in Frontiers in Genetics, entitled: 'Cancer-associated defects in the DNA damage response: drivers for malignant transformation and potential therapeutic targets' we have selected 10 papers that each discusses important, yet distinct aspects of the response to DNA damage in normal cells and cancer cells. Using an evolutionary conserved signaling network called the 'DNA damage response (DDR)' cells maintain the integrity of their genome, and thus safeguard cellular functioning and the ability to create viably progeny. Initially, the DDR appeared to consist of few linear kinase-driven pathways. However, research over the past decades in model organisms, as well as in the human system has revealed that the DDR is a complex signaling network, wired by multiple parallel pathways and displaying extensive crosstalk. Besides phosphorylation, multiple other post-translational modifications, including ubiquitination and sumoylation, are involved to achieve chromatin remodeling and initiation of DNA repair. Also, rather than being a cell-intrinsic phenomenon, we increasingly appreciate that cell-cell communication is involved. The recognition and repair of DNA damage is essential to maintain normal physiology. Multiple pathological conditions have been attributed to defective DNA repair, most notably accelerated aging, neurodegeneration and cancer. In the context of cancer, through repair of DNA damage or elimination of irreparably damaged cells, the DDR clearly has a tumor-suppressive role. Indeed, many tumor cells show partially inactivated DDR signaling, which allows proliferation in the context of DNA damage-inducing oncogenes. Simultaneously, loss of specific DDR signaling nodes creates a specific dependence of tumor cells on their remaining DDR components, and thus creates therapeutic opportunities. Especially in the context of cancer treatment, numerous targeted agents are under investigation, either to potentiate the cytotoxic effects of chemo-radiotherapy, or to induce synthetic lethality with cancer-specific alterations, with the treatment of BRCA1/2 mutant cancers with PARP1 inhibitors as a prototype example. We have selected four review articles that provide insight into the key components and the wiring of the DDR and DNA repair. Torgovnick and Schumacher review the involvement of DNA repair in the initiation and treatment of cancer, Brinkmann et al., describe the involvement of ubiquitination in DNA damage signaling and Jaiswal and Lindqvist discuss how cell-extrinsic signaling participates in communication of DNA damage to neighboring cells. In addition, Shatneyeva and colleagues review the connection between the cellular response to DNA damage and escape from immune surveillance. Concerning the therapeutic application of targeting the DDR and DNA repair, three articles were included. Krajewska and van Vugt review the wiring of homologous recombination and how this offers therapeutic opportunities. Additionally, Knittel and colleagues describe how genetic loss of the central DDR component ATM in chronic lymphocytic leukemia can be exploited therapeutically by targeting certain parallel DNA repair pathways. Syljuasen and colleagues report on how targeting of the DDR can be used as a therapeutic strategy in lung cancer. Finally, three chapters describe newly identified regulators of the cellular response to DNA damage. Von Morgen et al. describe the R2TP complex, Lezzi and Fanciluuli review the involvement of Che-1/AATF in the DDR, and Ohms and co-authors describe how retrotransposons are at the basis of increased genomic instability. Altogether, these articles describe how defective responses to DNA damage underlie disease - and especially in the context of cancer -can be exploited to better treat disease.

This book comprehensively reviews the role of cancer stem cells (CSCs) in cancer initiation, progression, and resistance to anticancer therapies. The initial chapters examine the methods and procedure of the detection, isolation, and characterization of CSCs. It also introduces various epigenetic pathways that contribute to cancer initiation and tumorigenesis, particularly regarding the maintenance and survival of CSCs. It also explores the role of CSCs metabolism and the mechanisms of metabolic plasticity of CSCs in cancer biology. Further, it also presents the implications of CSCs on the origin of tumor heterogeneity and on heterogeneity of the therapeutic response. Towards the end, this book highlights the different immunotherapeutic approaches targeting CSCs with the potential of strongly improving cancer outcomes. This book offers a broad framework to scientists and clinicians into the state-of-the-art knowledge on cancer stem cell biology and highlights their therapeutic implications. ​

The Cancer Stem Cell Niche, Volume Five in the Advances in Stem Cells and their Niches series, highlights new advances in the field, with this new volume presenting interesting chapters on a variety of timely topics, including Acute lymphoblastic leukemia and the bone marrow microenvironment, Stem cell niches in bone and their roles in cancer metastasis, The role of vasculature in cancer stem cell niches, The lung cancer stem cell niche, The prostate cancer stem cell niche: Genetic drivers and therapeutic approaches, Impact of prostate cancer stem cell niches on prostate cancer tumorigenesis and progression, The testicular cancer stem cell niche. Provides the authority and expertise of leading contributors from an international board of authors Presents the latest release in the Advances in Stem Cells and their Niches series Includes the latest information on the Cancer Stem Cell Niche

The identification of normal and breast cancer stem cells has offered a new vision of this heterogeneous disease and new hopes for its prognosis and treatment. This volume provides an overview of recent developments in mammary stem cell research and discusses the many varieties of approaches used by researchers to investigate the properties and functions of mammary stem cells. The beginning chapters provide readers with an introduction to mammary stem cells, and the processes used to characterize stem cells and isolate them via fluorescent activated cell sorting. The next few chapters discuss DNA and mRNA sequencing, proteomic techniques to help profile cells, lentiviral cell transduction for gene expression, and in vivo lineage tracing. The final few chapters are dedicated to following stem cells from their initial niche to the new microenvironment at their metastasis site, and to studying these cells using physical and mathematical approaches. Written in the highly successful Methods in Molecular Biology series format, the chapters include the kind of detailed description and implementation advice that is crucial for getting optimal results in the laboratory. Authoritative and cutting-edge, Mammary Stem Cells: Methods and Protocols aims to help members of the scientific community explore the behavior of stem cells and how to work with them in order to guide the design of new and complimentary strategies to be applied in the clinic with the ultimate end goal of fighting breast cancer.