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Your Environment. Your Health.

ARSENIC-INDUCED MIRNA-199 AND MIRNA-214 DEPLETE MITOCHONDRIAL DNA FOR THE GENERATION OF CANCER STEM-LIKE CELLS

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Principal Investigator: Chen, Fei
Institute Receiving Award Wayne State University
Location Detroit, MI
Grant Number R01ES028335
Funding Organization National Institute of Environmental Health Sciences
Award Funding Period 01 Sep 2018 to 31 May 2023
DESCRIPTION (provided by applicant): We have shown that consecutive treatment of the human bronchial epithelial cells with the environmentally relevant concentration of As3+ (0.125 – 0.25M), an environmental metalloid metal, for six months, induces transformation of the human bronchial epithelial cells, some of which possess characteristics of the cancer stem-like cells (CSCs), such as tumor sphere formation in vitro, self- renewal in vivo, increased expression of the stemness genes, including Oct4, Sox2, KLF4, and c-myc. In addition, these cancer stem-like cells exhibited a pronounced increase in the expression of several microRNAs, most notably, the miR-214, miR-199, miR-10b, miR-34b, etc. Furthermore, integrated transcriptomic and metabolomic analyses demonstrated a higher rate of glycolysis and lower levels of mitochondrial metabolism due to mitochondrial DNA (mtDNA) depletion among these As3+-induced CSCs. Lastly, a unique glycolytic feature that is different from naïve embryonic stem cells (ESCs) and cancer cells was found in these As3+-induced CSCs. Both ESCs and cancer cells direct glycolysis for lactate production. In contrast, the As3+-induced CSCs show increased conversion of the glycolytic intermediates into the subsidiary pathways for the generation of N-acetylglucosamine important for O- GlcNAcylation of the stemness genes and the S-adenosyl methionine (SAM) that contributes to DNA and histone methylation. Accordingly, the goal of this application is to determine: (1) is As3+-induced miRNAs, esp. miR214/199, responsible for the depletion of mtDNA and the consequent inhibition of mitochondria; (2) if so, how miRNAs induced by As3+ impairs the integrity and function of mtDNA and mitochondria; and (3) how the impaired function of mitochondria contributes to the generation of the CSCs induced by As3+. We hypothesize that As3+-induced JNK-dependent pSTAT3S727 and miR-214/199 switch mitochondrial OXPHOS to glycolysis for the formation of CSCs. To test this hypothesis, the following three specific aims are proposed: Specific Aim 1: As3+-activated JNK and pSTAT3S727 enforce expression of miR-214 and miR-199 that down-regulate mitochondrial transcription factor A (TFAM) in BEAS-2B and other lung cells for the generation of CSCs. We will focus on the transcriptional regulation of the miR-214/199 cluster with emphases on promoter DNA methylation and transcription factor binding in cellular response to As3+ and its down-stream signaling; Specific aim 2: Understand how As3+-induced JNK, miR-214/199 and mitochondrial dysfunction contribute to the formation of CSCs with an emphasis on metabolic reprogramming from OXPHOS to glycolysis. Specific Aim 3: Defining the causal roles of As3+-induced JNK- and miR-214/199-dependent metabolic reprogramming in the changes of epigenetics related to chromatin structure and accessibility that linked to self-renewal and/or differentiation of the As3+-induced CSCs through high-throughput profiling. We will identify metabolite- dependent epigenetic and chromatin changes in non-transformed cells, As3+-induced transformed cells and CSCs, which will be further verified through overexpressing or CRISPR-Cas9-based knockdown of the key genes in the related metabolic pathways and monitoring the self-renewal and differentiation status of the CSCs. The high-throughput approaches will include ChIP-seq to map H3K9me3, H3K27me3, and H3K4me3, and RNA-seq to profile transcription of the genes, esp. for those contributing to the pluripotency, self-renewal and differentiation of the CSCs. We anticipate that the results from the proposed studies will unravel importance of As3+-induced miR-214/199 on the generation of CSCs and lead to emerging of new concepts of As3+ carcinogenesis by emphasizing the capability of As3+ in CSC induction. Moreover, we believe that the date generated from this project will help us in developing novel therapeutic strategies by targeting JNK, miR-214/199 and CSCs through utilizing our unique mouse orthotopical lung cancer model in NOD/SCID mice in a separate research project.
Science Code(s)/Area of Science(s) Primary: 01 - Basic Cellular or Molecular processes
Publications See publications associated with this Grant.
Program Officer Daniel Shaughnessy
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