The hypothesis that this proposal seeks to test is that CBP2/Hsp47 constitutes a portion of the regulatory complexity that determines whether collagen XVIll (col 18) is produced and processed to function as a motogen or as an endostatin (ES). Moreover, that CBP2/Hsp47 and col 18 form an integral component of the angiostatic-angiogenic switching axis that ensures tumor growth and promotes invasion. This proposal seeks to prove that during normoxia col 18 with the aid of CBP2/Hsp47 is produced and secreted where it may itself or processed by matrix metalloproteinases to motogenic fragments promote tumor cell motility and invasion. However, at low microenvironmental pH resulting from hypoxia or necrosis, col 18 is processed by cathepsin L, unless inhibited by extracellular CBP2/Hsp47, to ES. Endostatin inhibits tumor cell motility and invasion until and proangiogenic signaling establishes a neovasculature that reestablishes normoxia. The proposed research will be accomplished through the completion of the following specific aims: 1) demonstrate that short form of collagen XVIII (lacking the frizzled domain) promote tumor cell motility and invasion using in vitro models. Then show that proteolytic fragments of collagen XVilI, particularly the trimerized NC1 domain and fragments produced following matrix metalloproteinase activity are likewise motogenic while the carboxyl terminus, endostatin domain, inhibits both motility and invasion; 2) determine whether CBP2/Hsp47 constitutes an important feature of the regulatory complexity that controls collagen XVill by over expressing or knocking out CBP2/Hsp47 in human oral squamous carcinoma tumor cell lines; 3) Determine the signaling pathways by which collagen XVII! promotes tumor cell invasion and the feedback mechanism(s) by which its' C-terminal fragment, endostatin, functions as an antagonist and 4 )provide the proof in practice that in solid human tumors CBP2/Hsp47 and the microcellular environment constitute important features of the regulatory complexity that control patterns of tumor cell growth and invasion by regulating the production and processing of collagen XVIII. These studies will aid in correlating the gene transcription profiles, and repertoire of proteins expressed and their activities with functional status of both normal and aberrant cells.
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