ZIA BC 011115 (ZIA) | |||
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Title | Epigenetic Mechanisms of Gene Expression in Thoracic Malignancies | ||
Institution | NCI, Bethesda, MD | ||
Principal Investigator | Schrump, David | NCI Program Director | N/A |
Cancer Activity | N/A | Division | CCR |
Funded Amount | $1,126,820 | Project Dates | null - null |
Fiscal Year | 2018 | Project Type | Intramural |
Research Topics w/ Percent Relevance | Cancer Types w/ Percent Relevance | ||
Cancer (100.0%) |
Esophagus (20.0%) Lung (80.0%) |
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Research Type | |||
Cancer Initiation: Alterations in Chromosomes Systemic Therapies - Discovery and Development |
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Abstract | |||
Novel in-vitro models and correlative experiments with primary tumor/normal tissue specimens have been utilized to identify epigenomic alterations which contribute to initiation and progression of thoracic malignancies. For example, comprehensive analysis of long non-coding RNA (lncRNA) perturbations during pulmonary carcinogenesis demonstrated that cigarette smoke condensate (CSC) significantly increased expression of lncRNA ZFAS1 while decreasing expression of ZNFX1, an uncharacterized, putative tumor suppressor gene. ZFAS1 expression correlated inversely with ZNFX1 expression in primary lung cancers relative to paired normal lung tissues. Over-expression of ZFAS1 or ZNFX1 increased or decreased, respectively, growth and invasion of lung cancer cells in-vitro and in-vivo. Mechanistic studies demonstrated that ZFAS1 functions as a scaffold to recruit DNMTs and polycomb proteins to the ZNFX1 promoter to silence this tumor suppressor gene in respiratory epithelial cells following cigarette smoke exposure. CSC-mediated activation of ZFAS1 coincided with recruitment of miR-31 as well as SP1 to the ZFAS1 regulatory region. Mithramycin, an antineoplastic agent currently in clinical trials in my Section repressed ZFAS1 and induced ZNFX1 expression in lung cancer cells in-vitro and in-vivo. A comprehensive manuscript pertaining to these experiments is presently under peer review. Decreasing cigarette consumption in the U.S. due to public education and tobacco reform has been offset recently by the use of relatively unregulated cigarette alternatives, such as communal smoking of hookah tobacco (shisha) via waterpipe. Although hookah is perceived to be a safe alternative to cigarette smoking, the effects of hookah smoke in respiratory epithelia have not been well characterized. A series of experiments have been conducted to examine the epigenenomic and transcriptomic effects of hookah smoke relative to conventional cigarette smoke in normal and immortalized human respiratory epithelial cells. Briefly, primary normal human small airway epithelial cells (SAEC) from three donors, as well as cdk4/hTERT-immortalized SAEC and human bronchial epithelial cells (HSAEC and HBEC, respectively) were cultured for 5 days (short-term) or > 12 months (long term) in normal media with or without cigarette smoke condensates (CSC; 0.05 or 0.1 mg/ml) or water pipe condensates (WPC; 1-2 mg/ml). Short term CSC and WPC exposures mediated dose-dependent growth inhibitory effects in cultured respiratory epithelia cells, which coincided with significantly reduced levels of global H4K16Ac and H4K20me3. CSC and WPC mediated distinct as well as overlapping cancer-associated gene expression signatures that were cell line and dose dependent. 73 genes were commonly regulated by CSC 0.05 mg/ml across three SAEC lines, HBEC, and HSAEC, whereas 157 genes were commonly regulated by CSC 0.1 mg/ml across these five cell lines. In contrast, 34 genes were commonly regulated by WPC 1 mg/ml, and 85 genes were commonly regulated by WPC 2 mg/ml across these five lines. 15 genes were commonly regulated by CSC 0.05 mg/ml and WPC 1 mg/ml across the three SAEC lines, HBEC and HSAEC, whereas 39 genes were commonly regulated by CSC 0.1 mg/ml and WPC 2 mg/ml across the five respiratory epithelial cell lines. Eight genes were commonly modulated by all four condensate exposures across all five cell lines. Notably, one of these genes (epiregulin; EREG) is significantly up-regulated in lung cancers, and correlates inversely with survival in lung cancer patients. Mechanistic studies demonstrated that CSC and WPC mediate demethylation of the EREG promoter in NREC. Results of these short-term exposure experiments, which represent the most comprehensive analysis of either cigarette or hookah smoke in human respiratory epithelial cells are in the final stages of preparation for publication. Additional studies have been conducted to examine the effects of long term WPC relative to CSC exposures i |