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EHS Center in Molecular and Cellular Toxicology with Human ApplicationsRaymond F Novak, Ph.D. Project DescriptionThe EHS Center in "Molecular and Cellular Toxicology with Human Applications" headquartered in the Institute of Environmental Health Sciences (IEHS) at Wayne State University (WSU) focuses on the stimulation of collaborative interdisciplinary, multidisciplinary research employing contemporary molecular, cellular, genomic and proteomic approaches to the study of environmental agent (e.g. organochlorines/PAH/solvents and particulates; major urban/Southeastern Michigan concerns) effects on gene expression, cell signaling and function, and human populations. Disease emphasis includes asthma, hepatic dysfunction in metabolic diseases (e.g. diabetes, inflammation, dislipidemias), reproductive and neurological disorders, and cancer. The EHS Center consists of an Administrative Core, three Research Cores, four Facility Cores, a COEP, a Pilot Project Program and an Enrichment Program. The Research Cores, "Gene Regulation and Genetics", "Cell Signaling and Function" and "Environmental Epidemiology", contain 43 faculty from three schools/colleges, three centers and five departments. The "Cell Culture", "Imaging and Cytometry", "Microarray and Bioinformatics" and "Protein Interaction and Proteomics" Facility Cores exist in dedicated space with assigned personnel to support research. The Microarray and Bioinformatics Facility Core includes Agilent and ABI equipment, Sun computers, analysis software (e.g. Rosetta Resolver(R) and bioinformatics expertise to assist with global gene expression analysis and the association of genetic factors (i.e. SNPs (polymorphisms), mutations) with disease. A Protein Interaction and Proteomics Facility Core has been initiated with the purchase of major equipment. An active COEP, includes K-12 curricula, science camps, competitive science awards, high school teacher training, and dissemination of information to the community. The Pilot Project Program contains escalating incentive funding for collaborative, interdisciplinary, multidisciplinary research proposals; supplemental funds for scored, not funded, grants may be provided. Professional growth is stimulated through an Enrichment Program (i.e. a seminar series and an Annual Thematic Symposium offering Category I Continuing Medical Education credits). The EHS Center provides Center Members with the opportunity and resources for collaborative interdisciplinary/multidisciplinary research, involving bench scientists, bioinformaticists, structural biologists, population scientists, physician-scientists and graduate students, to examine the role of environmental agents in disease. Program HighlightsBreast Cancer Development and ProgressionThe role of environmental stressors in human breast cancer, based on population studies, has been controversial. Mechanistic studies to examine the role of environmental factors in the initiation and/or promotion of breast cancer have been plagued by the absence of a suitable human system. Center investigators have developed and refined a xenograft system of human breast cancer. This system consists of human breast epithelial cell lines, with increasing risk of tumorigenicity, which when implanted subcutaneously in mice, progress through all the pathologic stages of breast cancer in 20% of the cases. This approximates the one in eight (i.e. 12%) life-time risk of a woman developing breast cancer. This series of cells also recapitulates the decade-long process for breast cancer development. This model replicates the chronological stages of the disease, and consists of numerous variants of the human breast epithelial cell line MCF10A. The MCF10AT1 variant is premalignant; estrogen accelerates progression of MCF10AT1 to cancer in an animal model. There are regions of chromosomes that are frequently amplified in cancer. These regions contain many genes with unknown roles in cancer. The MCF10A cells have been used to identify the specific amplified genes that act as oncogenes in a chromosomal region that is amplified in 15% of breast cancer (1,2). The panel of MCF10 cells is being used to assess changes in proteins that occur with progression as well since proteins are the actual effector molecules for cell function (3,4). Comparison of estrogen- regulated proteins in the premalignant breast cells with those that are constitutively altered in two malignant MCF10 variants has identified six proteins upregulated in both malignant lines and induced in premalignant cells by estrogen and two that are constitutively downregulated in both malignant lines and downregulated in premalignant cells by estrogen. Of these eight proteins, one effects signaling by the H-ras oncogene and five have a role in cell survival by regulating apoptosis. In addition, another premalignant MCF10 variant has been derived that does not depend on mutant H-ras and will allow analysis of progression based on two different oncogenic pathways (5).
Mediators of Arsenic Uptake in Mammalian CellsArsenic exposure is associated with hypertension, diabetes and cancer. The metalloid ranks first on the US governments Superfund priority list of hazardous substances. The physiological consequences of arsenic exposure are influenced by processes involved in its uptake, metabolism and efflux from cells. Previously the Rosen laboratory established that hexose permeases and aquaporins 7 and 9 (AQP7 and 9) facilitate the influx of arsenic trioxide, the principal form of trivalent inorganic arsenic in solution at physiologic pH (1, 2). Recent studies funded by a Center Pilot Award have established that AQP9 also bidirectionally transports methylarsonous acid, the monmethylated metabolite of arsensic trioxide (3). Methylarsonous acid is formed in the liver, and constitutes a putative detoxification product that can be excreted in the bile or urine. The Rosen laboratory has also found that the mammalian glucose permease GLUT1 is an efficient transporter of arsenic trioxide and methylarsonous acid (4). This is an important finding since GLUT1 has high affinity for these molecules, and unlike AQP7 and 9, is ubiquitously expressed in mammalian tissues, including the epithelial cells that form the blood-brain barrier. Presumably, GLUT1 maybe a major mediator of arsenic uptake in mammalian cells. Finally, in a project also funded by a Center Pilot Award, performed in collaboration with Center member Dr. Ho, the Rosen laboratory generated Asna1 knockout mice (5). The Asna1 gene is the mammalian homologue of the bacterial ArsA ATPase, a component of an arsenic pump that confers resistance to arsenicals and antimonials. Whereas Asna1 heterozygous knockout mice were viable, early embryonic lethality was observed in homozygous knockouts. Presumably, the product of the gene is critical for early developmental processes.
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