EPIGENETIC REGULATION IN HYPOXIC CANCER CELLS
Yun Zhong
Yale Universitycity: New Haven country: United States (us)
Grant 5R01CA148996-03 from National Cancer Institute
Keywords: Affect; base; Biological Assay; BRCA1 gene; Breast; Breast Cancer Cell; Cancer Biology; cancer cell; Cancer stem cell; Cell Culture Techniques; Cell Differentiation process; Cells; Characteristics; chromatin modification; chromatin remodeling; Disease Outcome; DNA; DNA Repair; DNA Repair Gene; Down-Regulation; Epigenetic Process; Epithelial Cells; Family; gene repression; Genes; Genetic; Genetic Transcription; histone modification; Histones; Human; Hypermethylation; Hypoxia; Lead; Link; Maintenance; Malignant - descriptor; malignant breast neoplasm; Malignant Neoplasms; Mammary gland; Mediating; MicroRNAs; Mismatch Repair; MLH1 gene; Modeling; MSH2 gene; Nucleotide Excision Repair; Pathway interactions; Population; prevent; prognostic; Promotor (Genetics); Proteins; public health relevance; Publishing; Regulation; repaired; Repression; response; Role; Solid Neoplasm; Stem cells; stemness; Stress; Testing; transcription factor; tumor; Tumorigenicity; Work
Relevance: Hypoxia is a critical feature of solid tumors and has profound effects on cancer biology. We have found that hypoxia is a cause of genetic instability due to transcriptional repression of several key DNA repair factors, including BRCA1. In addition, we have identified hypoxia-induced microRNAs that regulate the expression of other DNA repair factors. Our work has also shown that hypoxia can inhibit differentiation, and other studies have shown that BRCA1, itself, can alter differentiation of mammary cells. Since both hypoxia and BRCA1 can affect gene transcription, we hypothesize that both hypoxia and BRCA1 may regulate the differentiation of breast cancer cells via differential expression of microRNAs. Because hypoxia represses BRCA1 expression, this could provide another potential mechanism by which hypoxia promotes malignant progression by repressing BRCA1 and thus enhancing stem cell characteristics of breast cancer cells. In this project, we will examine epigenetic pathways that suppress of BRCA1 in response to hypoxia, with a specific focus on chromatin modifications and the factors that may mediate them. We will also test the hypothesis that hypoxia-mediated suppression can lead to long-term repression of the BRCA1 gene promoter, providing a potential explanation for the finding that this gene is often silenced in sporadic cancers. We will also investigate the role of BRCA1 and hypoxia in the regulation of microRNAs in breast cancer cells and in mammary progenitor cells. The functional consequences of selected microRNA changes will be tested with respect to differentiation of breast cancer cells or mammary progenitor cells and with respect to the maintenance of stemness and tumorigenicity of breast cancer cells
Project start date: 2010-03-04
Project end date: 2014-12-31
Budget start date: 1-JAN-2012
Budget end date: 31-DEC-2012
5R01CA148996-03 (2012): $299800
Sponsored Links Excellgen http://Excellgen.com
EPIGENETIC REGULATION IN HYPOXIC CANCER CELLS
Yun Zhong, Professor
Yale Universitycity: New Haven country: United States (us)
Grant 5R01CA148996-02 from National Cancer Institute
Abstract: Hypoxia is a critical feature of solid tumors and has profound effects on cancer biology. We have found that hypoxia is a cause of genetic instability due to transcriptional repression of several key DNA repair factors, including the DNA mismatch repair (MMR) factors, MLH1 and MSH2, and the homology-dependent repair (HDR) factors, RAD51 and BRCA1. In addition, we have identified hypoxia-induced microRNAs (specifically miR-210 and miR-373) that regulate the expression of other DNA repair factors. Moreover, there is accumulating evidence that both hypoxia and altered BRCA1 levels can influence cell differentiation. Our work so far has shown that hypoxia can inhibit differentiation in several cell culture models, and other studies have shown that BRCA1 can alter differentiation of mammary progenitor cells and breast epithelial cells. Since both hypoxia and BRCA1 can affect gene transcription, our working hypothesis is that both hypoxia and BRCA1 may regulate the differentiation of breast cancer cells via differential expression of microRNAs. Because hypoxia represses BRCA1 expression, this could provide another potential mechanism by which hypoxia promotes malignant progression by repressing BRCA1 and thus enhancing stem cell characteristics of breast cancer cells. In Aim 1 of this project, we will examine epigenetic pathways that may regulate the expression of the BRCA1 gene in response to hypoxia, with a specific focus on chromatin modifications and the factors that may mediate them. We will also test the hypothesis that hypoxia-mediated suppression can lead to long-term repression of the BRCA1 gene promoter, providing a potential explanation for the frequent finding that this gene is silenced in sporadic cancers. In Aim 2, we will investigate the role of BRCA1 in the regulation of microRNA expression in breast cancer cells and in human mammary progenitor cells under hypoxic or normoxic conditions. The functional consequences of selected microRNA changes will be tested with respect to differentiation of breast cancer cells or mammary progenitor cells and with respect to the maintenance of stemness and tumorigenicity of breast cancer cells. Hypoxia is a critical feature of solid tumors and has profound effects on cancer biology. We have found that hypoxia is a cause of genetic instability due to transcriptional repression of several key DNA repair factors, including BRCA1. In addition, we have identified hypoxia-induced microRNAs that regulate the expression of other DNA repair factors. Our work has also shown that hypoxia can inhibit differentiation, and other studies have shown that BRCA1, itself, can alter differentiation of mammary cells. Since both hypoxia and BRCA1 can affect gene transcription, we hypothesize that both hypoxia and BRCA1 may regulate the differentiation of breast cancer cells via differential expression of microRNAs. Because hypoxia represses BRCA1 expression, this could provide another potential mechanism by which hypoxia promotes malignant progression by repressing BRCA1 and thus enhancing stem cell characteristics of breast cancer cells. In this project, we will examine epigenetic pathways that suppress of BRCA1 in response to hypoxia, with a specific focus on chromatin modifications and the factors that may mediate them. We will also test the hypothesis that hypoxia-mediated suppression can lead to long-term repression of the BRCA1 gene promoter, providing a potential explanation for the finding that this gene is often silenced in sporadic cancers. We will also investigate the role of BRCA1 and hypoxia in the regulation of microRNAs in breast cancer cells and in mammary progenitor cells. The functional consequences of selected microRNA changes will be tested with respect to differentiation of breast cancer cells or mammary progenitor cells and with respect to the maintenance of stemness and tumorigenicity of breast cancer cells
Keywords: Affect; Assay; base; Bioassay; Biologic Assays; Biological Assay; brca 1 gene; BRCA1; BRCA1 gene; Breast; Breast Cancer 1 Gene; Breast Cancer 1, Early Onset Gene; Breast Cancer Cell; Breast Cancer Type 1 Susceptibility Gene; Cancer Biology; cancer cell; Cancer of Breast; Cancer stem cell; Cancers; Cell Culture Techniques; Cell Differentiation; Cell Differentiation process; Cells; Characteristics; chromatin modification; chromatin remodeling; COCA1; COCA2; Deoxyribonucleic Acid; Disease Outcome; DNA; DNA Damage Repair; DNA Repair; DNA Repair Gene; Down-Regulation; Down-Regulation (Physiology); Downregulation; Epigenetic; Epigenetic Change; Epigenetic Mechanism; Epigenetic Process; Epithelial Cells; Family; FCC1; FCC2; Gene Down-Regulation; gene product; gene repression; Gene Transcription; Genes; Genetic; Genetic Transcription; heavy metal lead; heavy metal Pb; Hereditary Breast Cancer 1; histone modification; Histones; hMLH1; HNPCC; HNPCC1; HNPCC2; Human; Human Breast Cancer Cell; Human, General; Hypermethylation; Hypoxia; Hypoxic; Lead; Link; Maintenance; Maintenances; malignancy; Malignant; Malignant - descriptor; malignant breast neoplasm; Malignant Cell; Malignant neoplasm of breast; Malignant Neoplasms; Malignant Tumor; Malignant Tumor of the Breast; mammary; Mammary gland; Mammary Glands, Human; Man (Taxonomy); Man, Modern; Mediating; MGC5172; Micro RNA; MicroRNAs; miRNA; Mismatch Repair; MLH1; MLH1 gene; MMR; Modeling; Mother Cells; MSH2; MSH2 gene; neoplasm/cancer; Nucleotide Excision Repair; Oxygen Deficiency; pathway; Pathway interactions; Pb element; Population; Post-Replication Mismatch Repair; prevent; preventing; Progenitor Cells; prognostic; Promoter; Promoters (Genetics); Promotor; Promotor (Genetics); Proteins; PSCP; public health relevance; Publishing; Regulation; repair; repaired; Repression; response; RNA Expression; RNF53; Role; social role; Solid Neoplasm; Solid Tumor; Stem cells; stemness; Stress; Testing; Transcription; transcription factor; Transcription Repression; Transcription, Genetic; Transcriptional Repression; tumor; Tumorigenicity; Unscheduled DNA Synthesis; Work
Relevance: Hypoxia is a critical feature of solid tumors and has profound effects on cancer biology. We have found that hypoxia is a cause of genetic instability due to transcriptional repression of several key DNA repair factors, including BRCA1. In addition, we have identified hypoxia-induced microRNAs that regulate the expression of other DNA repair factors. Our work has also shown that hypoxia can inhibit differentiation, and other studies have shown that BRCA1, itself, can alter differentiation of mammary cells. Since both hypoxia and BRCA1 can affect gene transcription, we hypothesize that both hypoxia and BRCA1 may regulate the differentiation of breast cancer cells via differential expression of microRNAs. Because hypoxia represses BRCA1 expression, this could provide another potential mechanism by which hypoxia promotes malignant progression by repressing BRCA1 and thus enhancing stem cell characteristics of breast cancer cells. In this project, we will examine epigenetic pathways that suppress of BRCA1 in response to hypoxia, with a specific focus on chromatin modifications and the factors that may mediate them. We will also test the hypothesis that hypoxia-mediated suppression can lead to long-term repression of the BRCA1 gene promoter, providing a potential explanation for the finding that this gene is often silenced in sporadic cancers. We will also investigate the role of BRCA1 and hypoxia in the regulation of microRNAs in breast cancer cells and in mammary progenitor cells. The functional consequences of selected microRNA changes will be tested with respect to differentiation of breast cancer cells or mammary progenitor cells and with respect to the maintenance of stemness and tumorigenicity of breast cancer cells
Project start date: 2010-03-04
Project end date: 2014-12-31
Budget start date: 1-JAN-2011
Budget end date: 31-DEC-2011
PFA/PA: PA-07-070
5R01CA148996-02 (2011): $309071
Grants awarded to Yun Zhong
ROLE OF HYPOXIA IN THE REGULATION OF CANCER CELL DIFFERENTIATION
Yun Zhong, Associate Professor
Yale Universitycity: New Haven country: United States (us)
Grant 5R01CA125021-05 from National Cancer Institute
Abstract: Hypoxia is a common feature of solid tumors and predicts poor clinical outcome. Hypoxic tumor cells are resistant to radiation therapy and exhibit more aggressive phenotype. It has been suggested that hypoxic tumor cells possess undifferentiated characteristics and highly aggresive properties. Other evidence suggests that undifferentiated cells may potentially be more resistant to radiation than are differentiated cells, and recently, the hypoxia-inducible factor-1 (HIF-1) has been implicated in the regulation of radiation sensitivity of solid tumors. However, it remains unclear how hypoxia regulates tumor cell differentiation. We have begun to investigate the role of hypoxia in regulating cell differentiation using several model systems. Our data have shown that hypoxia inhibits cell differentiation and can arrest precursor/stem cells in their undifferentiated state. In our preliminary studies, we have aslo found that hypoxia inhibits differentiation of cancer cells and protects their clonogenic potential. These lines of evidence prompt us to hypothesize that hypoxia promotes tumor malignancy and resistance to radiation therapy, in part, by maintaining tumorigenic cells in their undifferentiated state. In this proposal, we will use neuroblastoma as a model to test this hypothesis by focusing on the following four working hypotheses. 1. Hypoxia inhibits differentiation of neuroblastoma cells in vitro. 2. Hypoxia maintains the poorly differentiated neuroblastoma cell population in hypoxic tumors. 3. The hypoxia inducible factor (HIF) regulates undifferentiated phenotype of neuroblastoma cells. 4. Hypoxia induces dedifferentiation of neuroblastoma. This proposal is innovative as it addresses the regulation of stem/precursor phenotype by tumor microenvironment, an important mechanism for tumor progression that has not yet been well understood. Our proposal will potentially provide new insight into how hypoxia increases tumor resistance to therapy and promotes malignant progression. Such insight could lead to new strategies to target the regulation of tumor cell differentiation as a form of cancer therapy
Keywords: Address; Affect; Apoptosis; base; Biological Assay; Biological Models; cancer cell differentiation; cancer therapy; carbonate dehydratase; Cell Differentiation process; Cell Line; Cell surface; cell type; Cells; Characteristics; Clinical; Data; Differentiation Antigens; Exhibits; Flow Cytometry; Genes; Genomic Instability; Hypoxia; Hypoxia Inducible Factor; hypoxia inducible factor 1; Immunohistochemistry; In Vitro; innovation; insight; Lead; Maintenance; Malignant - descriptor; Malignant Neoplasms; Mediating; Modeling; mutant; MYCN gene; nature therapy; neoplastic cell; nerve stem cell; Neuroblastoma; Normal Cell; novel; Outcome; Pathway interactions; Phenotype; Population; population based; precursor cell; prevent; Property; Radiation; Radiation therapy; Radiation Tolerance; Regulation; Research Personnel; Resistance; Role; Series; Small Interfering RNA; Solid Neoplasm; stem; Stem cells; Testing; therapy resistant; tumor; tumor progression; tumor xenograft; tumorigenic; Tumorigenicity; Undifferentiated; Work
Project start date: 2007-07-01
Project end date: 2012-03-31
Budget start date: 1-APR-2011
Budget end date: 31-MAR-2012
5R01CA125021-05 (2011): $283005