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Research Interests:
STEM CELLS AND CANCER
Recent data suggest that cancers may originate and recur based on the existence of rare tumor "stem" cells serving as the underlying site and source of tumorigenesis. These stem cells exist in normal organs as a quiescent resource for repair and regeneration but can undergo transformation producing aberrant cancer cells. We have undertaken studies to identify and isolate normal and "tumor" stem cells in the prostate using properties defined by a human embryonic stem cell line (HSF-1) as a reference for comparison. Selective media conditions and substrates established for culture of embryonic stem cell lines in our laboratory have been utilized to screen normal prostate and tumor biopsies for the presence of putative stem cells. While the bulk of epithelial, stromal and tumor cells are not supported by these conditions, we have been able to isolate and amplify a population of colony-forming cells from biopsies that exhibit behavior similar to that of classical embryonic stem cells. These cells isolated in vitro have been subsequently characterized using a battery of immunocytochemical markers for pluripotency, prostate organ specificity and tumorigenesis. The colony-forming cells from both donors and tumors express markers of pluripotency in media with reduced growth factors but can be induced to differentiate down multiple germ layer pathways by altering the media growth factor composition. Furthermore, stem cells derived from prostate tumors exhibit differential expression of tumor markers compared to comparable cells derived from donor prostates. In vivo testing has been performed by suspension of prospective stem cells in a collagen matrix with urogenital mesenchyme and then placing these tissue recombinants under the kidney capsule of SCID mice. The stem cell recombinants derived from donor prostates formed glandular structures similar to those of mature prostate while recombinants comprised of other prostate cells did not. Immunohistochemical labeling with an antibody for prostate specific antigen (PSA) indicated that the glandular structures formed by the stem cell recombinants expressed PSA consistent with their behavior as a prostate progenitor. Ongoing studies are focused on repeating these studies using stem cells derived from tumor biopsies to determine if they form normal prostate glands or prostate tumors in vivo.
MYOCARDIAL INFARCT AND REPAIR
Prevailing dogma regarding heart repair assumes that ventricular cardiomyocytes undergo mitotic arrest soon after birth thereby limiting the myocardial regenerative response to injury. Recent findings challenged this theory by demonstrating 1) cardiomyocyte replication in vivo and 2) identification of putative cardiac progenitor cells in the myocardium. We have been addressing the hypothesis that factors secreted from nonmyocardial cells inhibit the native regenerative capacity of cardiomyocytes. Our studies demonstrated that cardiac fibroblasts block the proliferative behavior of neonatal cardiomyocytes in culture by production of cytokines associated with the TGF-beta pathway among others. Moreover, paracrine effects originating from cardiac fibroblasts alter the phenotype of cultured cardiomyocytes resulting in expression of myofibroblast properties (vimentin and smooth muscle actin expression). Thus these data suggest that cardiomyocytes exhibit a previously unrecognized epithelial to mesenchymal plasticity and may be influenced by surrounding fibroblast cells to adopt phenotypic behavior supporting scarification rather than regeneration.
A second experimental approach has been directed at testing whether stem cells impact neighboring cells either by direct contact or indirect paracrine effects. Specifically, we have been studying the effects of media conditioned by HSF-1 cells as an adjunct to the standard media used to maintain isolated neonatal rat cardiomyocytes. We have established that HSF-1 conditioned media induces at least two cycles of division in neonatal cardiomyocytes that does not occur in untreated controls. Genomics, proteomics and fractionation studies are currently underway to determine the protein signals and molecular pathways whereby this proliferative activation occurs. Studies are ongoing to translate this ability to activate ventricular cardiomycyte proliferation in vitro to the in vivo environment as a potential novel approach to support myocardial regeneration after ischemia and/or infarct.
HIGH THROUGHPUT GENOMICS & PROTEOMICS ASSAYS
Interrogation of genome-wide amounts of data has become possible with novel microarray tools designed for analysis of mRNA expression, DNA sequence structure/rearrangement, microRNA regulation, and vast protein networks. Dr. LaFramboise has collaborated with several industrial partners (Motorola, GE, Whatman) to develop and optimize tools for this purpose. Attendant with these powerful analytic capabilities are complicating issues of calibrating and standardizing arrays to provide high precision, sensitivity and reproducibility while simultaneously dealing with issues of massive parallel data acquisition, storage and interpretation. The laboratory has focused on developing protocols to streamline the use of microarrays without compromising the fidelity of the assays. For example, toxicological analysis of non-steroidal anti-inflammatory agents was performed using multiple replicates in which outliers were detected and eliminated thereby greatly enhancing the accuracy of the study. Changes in expression level correlated with hepatotoxicity and may provide a pathway toward developing serum-based screening tools to monitor drug toxicity. These procedures have similarly been applied to an experimental myocardial infarct model yielding a novel database of spatio-temporal changes in gene expression that occurred among survivors of LADC (left anterior descending coronary artery) ligation. These data have formed the basis for pursuit of blood borne biomarkers which may serve as diagnostic and/or prognostic indicators of cardiac injury.
Selected Publications:
LaFramboise WA, Scalise D, Stoodley P, Graner S, Guthrie RD, Magovern J, Becich M. Cardiac Fibroblasts Influence Cardiomyocyte Phenotype In Vitro. Am J Physiol Cell Physiol. 2007 Jan 17; [Epub ahead of print]
LaFramboise WA, Bombach KL, Pogozelski AR, Cullen RF, Muha N, Lyons-Weiler J, Dhir RJ, Spear SJ, Guthrie RD, Magovern JA. Hepatic Gene Expression Response to Acute Indomethacin Exposure. Molecular Diagnosis and Therapy. 2006: 10(3): 187-196.
Ma C, Lyons-Weiler M, Liang W, LaFramboise WA, Gilbertson JR, Becich MJ, Monzon FA. In vitro Transcription, Amplification and Labeling Methods Contribute to the Variability of Gene Expression Profiling with DNA Microarrays J Mol Diagn. 2006 J Mol Diagn. 2006; 8(2): 183-192.
LaFramboise WA, Bombach KL,Dhir RJ, Muha N, Cullen RF, Pogozelski AR, Turk D, George JD, Guthrie RD, Magovern JA. Molecular Dynamics of the Compensatory Response to Myocardial Infarct. Journ Mol Cellular Cardiology, 2005 1:103-117.
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