The long-term goal of this competing renewal is to understand the functions of perlecan, a major heparan sulfate proteoglycan of basement membranes and extracellular matrices, and to discern its roles in cancer and development. During the past four years we have elucidated the complete molecular architecture of its protein core by cDNA cloning, determined its genomic organization and chromosomal mapping, and discovered a widespread distribution of this gene product with novel antibodies against subdomains of the perlecan protein core. The central hypothesis of our research is that the aberrant expression of perlecan in the pericellular matrix of human colon cancer contributes to tumor growth. This working hypothesis is based on several key observations; (I) perlecan expression is elevated in colon cancer/ (ii) there is abundant deposition of this gene product in a around the newly-formed tumor blood vessels; (iii) perlecan is directly involved in the binding, storing and delivering of growth factors implicated in angiogenesis and tumor growth, and (iv) proliferating cells synthesize perlecan at high level. These observations indicate that perlecan plays a pivotal role not only in matrix assembly, but also in tumor promotion and invasion, and further suggest that perlecan is an important product that favors cellular growth in cancer and embryogenesis. Over the next five years we plan to investigate the biology of mammalian perlecan by utilizing a multidisciplinary approach including recombinant DNA and gene transfer technology, as well as biochemical ad immunological methods. Specifically, we plan to; (1) Investigate the expression of perlecan in human colon cancer, and establish whether altered perlecan gene expression correlates with the invasive behavior of human colon carcinoma (2) Investigate the mechanism of action of perlecan by studying the effects of lowering or abrogating its expression on the growth and metastatic potential of stably transfected colon cancer cells and (3) Investigate the role of perlecan in the developing embryo by generating transgenic animals in which the gene is disrupted via homologous recombination. These concerted research lines should provide information not only on the structural and functional roles of perlecan but should also firmly establish its role in tumorigenicity and ontogeny.
The first aim will provide baseline, systematic data required for clarifying the role of perlecan in the development of colon cancer, while the second aim will address more mechanistic questions regarding the function of this important macromolecule in growth control and invasion. The development of transgenic animals with targeted disruption of the perlecan gene should provide sound data as to the role of this molecule in developmental processes, provide novel avenues of research, and possible unravel unforeseen functions for this important gene during embryogenesis. The expected results could lead to future approaches of cancer prevention and treatment directed at hindering the expression of this proteoglycan thereby depriving the tumor cells of a macromolecule essential to their survival and growth.
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