Bioactive compound modulation of epigenetic regulator Sp1/NFkB/miR network in AML

点击翻译按钮获取中文摘要

DESCRIPTION (provided by applicant): Despite progress made in understanding the biological mechanisms of myeloid leukemogenesis, acute myeloid leukemia (AML) remains a deadly disease for most of the patients. It is well documented that silencing of tumor suppressor genes (TSGs) mediated by aberrant DNA methyltransferase (DNMT)-dependent DNA hypermethylation plays a critical pathogenic role in the development and progression of AML. Azanucleosides, i.e., decitabine, have been recently approved by FDA as hypomethylating agents and positive clinical outcome has been achieved for some patients. However, the clinical response is restricted to a minority of hematopoietic malignancies. Hence, further studies are urgently required to explore novel therapeutic strategies or agents to overcome the dismal outcome. Our long-term goals are to elucidate the regulatory mechanisms controlling DNA methylation thereby leukemogenesis as a prerequisite to the development of therapeutic protocols that can be used to attenuate the disease process. The objectives of this grant application are to explore novel DNA hypomethylation agents (DNMTi) with diverse structures through distinct mechanisms from decitabine. The specific hypothesis behind the proposed research is that bioactive food component Thymoquinone (TQ) may achieve higher efficacy of DNA hypomethylation through modulating methylation regulator Sp1/NFkB/miR network. That hypothesis is based on the following observations: 1) miR29b directly disrupts DNMT3a/3b and indirectly abolishes DNMT1 via impairment of its transactivator Sp1, thereby leading to DNA hypomethylation. 2) Sp1/NFkB complex suppresses miR29b expression and positively correlates to DNMT level in AML cell lines and patient samples, suggesting that DNA methylation is under control of a protein-miR network involving NFkB activity, Sp1/NFkB complex, DNMTs and miRs. 3) plant-derived drugs displayed efficiently anti-leukemic activities with huge therapeutic potentials, while the conventional medicine has lots of side effects, 4) TQ is a bioactive constituent and acts as anticancer agent, with minimal level of toxicity to normal cells, by significantly blocking NFkB signaling pathways. Based on these observations, the experimental focus of this proposal is on the hypomethylating effect of TQ in vitro and in vivo. The specific aims are designed to provide a comprehensive understanding of the mechanism(s) of TQ action(s) and to optimize the dose and schedule of administration of TQ effective against leukemic disease. The specific aims of this application are to: 1. Elucidate the mechanism of TQ antileukemic activity by the demonstration that TQ functions as DNA hypomethylation agent through Sp1/NFkB/miR29b network in AML cell lines and patient primary blasts. We will demonstrate that pharmacological modification of Sp1/NFkB/miR29b regulatory network by TQ induces DNA hypomethylation in vitro using i) Western blot and quantitative PCR (qPCR), ii) LC/MS/MS and iii) MTS and PI/AV staining. 2. Perform preclinical in vivo evaluation of the pharmacodynamic and pharmacokinetic activity of TQ in leukemic mice models. We will i) define the effective pharmacological dose and schedule of TQ administration that will modulate the misbalanced Sp1/NFkB/miR29b network thereby DNA hypomethylation in vivo using Western blot, qPCR, and LC/MS/MS, ii) determine the plasma and intracellular PK parameters of TQ and correlate these with PD and clinical efficacy endpoints, iii) determine the clinical efficacy measured by survival duration. This project will be carried out through an interdisciplinary approach by investigators with expertise in translational research (Liu) and PK/PD studies (Chan). If successful, the novel DNMTi can be applied to solid tumor or non-proliferating malignancies, this investigation may advance our understanding of epigenetic changes mediated by specific bioactive food component, the roles of Sp1/NFkB, miR and DNA methylation in leukemogenesis, the molecular pathways of TQ action and help us to adequately evaluate the specificity of individual nutrient.