Effects of Ingested Nanoparticles on Gene Regulation in the Colon
|Anticipated Total Funding||$200,000.00|
|Anticipated End Year||2009|
Objective: We will test the hypothesis that ingested nanoparticles are taken up by inflamed colon cells, translocate to the nucleus, and cause alteration of gene transcription. Colon cancer is a major cause of death, and any environmental agent that causes increased colon inflammation or affects the regulation of cell cycle genes is a logical concern. The goal of this toxicology study will be to quantify the ability of a suite of manufactured nanoparticles to affect inflamed versus non-inflamed colon cells and to elucidate the biochemical mechanisms linking particles to changes in gene regulation. This study is motivated by drug delivery studies showing that inflamed colon cells internalize nano particles, a paper reporting that silica particles translocate and bind nuclear proteins, and our preliminary gene array data showing that nano-sized silica affects the transcription of many genes associated with inflammation and cell cycle regulation. The research will focus on lower-cost carbon and metal oxide nanomaterials that are used commercially and therefore present the potential for human exposure by ingestion. Approach: The research will use established cellular imaging, molecular biology, and gene array technology and will build on the investigators existing projects in particle toxicology, cell signaling, and colon cancer. Particles will be characterized using electron microsopy, surface area analysis, and trace element analysis. An in vitro model consisting of cultured human colon-derived cells (CaCo-2 and RKO cells) will be treated with suspensions containing the nanoparticles or controls. Tissue inflammation will be modeled by pretreating the cells with TNF-_. Particle uptake and intracellular localization will be quantified by trace element analysis and by fluorescent probes. Particle-induced pro- and anti-inflammatory response will be measured by cytokine ELISA assays and cell death assessed by flow cytometry. Effects of the particles on gene regulation will be determined at the Microarray Core Facility using Agilent Full Human Genome 44K arrays, with confirmation of findings by quantitative real-time PCR. Expected Results: This exploratory study will test whether ingestion of certain commercially available manufactured nanoparticles is associated with altered inflammation and cell cycle pathway gene regulation in colon cells. The results will be useful for establishing whether the hypothesized effects represent a potential risk to human health and will help determine whether further animal or human exposure studies are justified.