Research / Clinical
Summary
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Diseases/Research Topics
Control of Differentiation and Development, Differentiation, Gene Regulation, Growth Control
Other Leadership Roles:
Leader, Digital Imaging Shared Resource
Project: Molecular mechanisms of loss of regulation in the muscle tumor, rhabdomyosarcoma
This work is being done with UCSD faculty, Drs. Michael Karin and Jean Wang, and is continuing with Drs. Lorenzo Puri and Mark Montminy at the Salk Institute. We have found a role for p38 SAPK in normal cell myogenesis and evidence for its defective nature in certain rhabdomyosarcoma cell lines. It has been shown that activating this pathway can partially restore normal myogenesis in these rhabdomyosarcoma cell lines. In addition, our collaborative group has found that the restoration of myogenesis in the rhabdomyosarcoma cell line, RD, by treatment with TPA requires the activation of p38 SAPK. To summarize, this work indicates a prominent role for this kinase pathway.
Project: Imaging of activated RAS in cancer cells and tissues
In collaboration with Dr. Gerry Boss of the Cancer Center, we are anaylzing the amount of GTP-bound RAS in tumor tissue sections using a single cell fluorescence-based assay recently developed by others. We believe that this will provide an important complementary approach to the established biochemical assays for this activated form of RAS developed by Dr. Boss and others. The microscopic approach will allow us to see and quantitate (within limits) this on a cell by cell basis in the tissues, where we expect to see heterogeneity between cells with regard to this activity. This is for several reasons. Tumor tissues contain normal cells in addition to malignant cells. Tumors are derived from clonal expansion of cells continually altered via genetic progression, ands so within a single tumor mass the population of malignant cells may be different with respect to RAS mutation (activation.) The biochemical assay developed previously by Dr. Boss and colleagues provides a view of activated RAS averaged over a population of cells present in the tissue sample. The microscopic assay will provide data on many individual cells within the tumor tissue sample. In addition, the latter assay will enable us to compare the levels of activated RAS in the normal cells that may be present in surrounding areas of the specimen, giving us an additional internal control for this technique. Furthermore, since we will be able to simultaneously measure in each image up to five independent fluorophores, we will be able to determine in each cell analyzed in the tissue sections other markers. These will include the status of other oncogenes or tumor suppressor genes, cytokeratins, DNA content, etc.
Multi-color 3-D data sets can be further visualized. Through a productive collaboration we have with the VisLab at the San Diego Supercomputer Center here at UCSD. They (e.g., Dave Nadeau, Jon Genetti, Alex Decastro) have put together various quantitative and visual tools under the auspices of NPACI (National Partnership for Advanced Computational Infrastructure), called Scalable Visualization Tools. In these views 3-D perspective is given to the data sets and 'fly-through' movies are made in which the viewpoint is continuously changed from outside to anywhere within the data. The software can simultaneously extract parallel views showing a particular quantitative feature of the data, such as overlapping colors of voxels or nearness of two colors in space. Altogether this software allows for enhanced extraction of information from the data sets. An example of this can be seen in a recent paper by Borsig, L.,Wong, R,Feramisco, J.R., Nadeau, D, Varki, N., and Varki. A. Platelets, P-selectin, heparin and cancer metastasis: new mechanistic connections with therapeutic potential. (PNAS 98:3352-3357, 2001.) Experiments of this type are especially interactive as they involve the Cancer Center's Data Compilation and Histolgy Shared Resources as well.
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