PILOT 2 IMPACT OF HYALURONAN TURNOVER ON SIGNALING THROUGH ENDOSOMA

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In aggressive prostate cancer, tumor cells manipulate the extracellular matrix in part by production and turnover of hyaluronan (HA), a glycosaminoglycan polymer. Although negligible in normal adult prostate, HA accumulates in prostate tumors and their resultant bone metastases. Quantification of tumor cell-associated HA and its turnover enzyme, the hyaluronidase Hyal1, predicts invasive clinical progression. Cell surface HA polymers, synthesized by HA synthase enzymes (HAS), and HA oligomers generated from the polymers by Hyal1, modulate signaling pathways that control proliferation and motility in an opposing fashion, at least partially by impacting activity of specific cell surface receptors. Specifically, overexpression of the HAS biosynthetic enzyme reduces plasma membrane levels of adhesion and growth factor receptors, and impairs both cell adhesion and motility. These effects are relieved by the concurrent presence of Hyal1, but the mechanism is not understood. This proposal will pursue the novel observation that elevated Hyal1, which is both a secreted and a lysosomal enzyme, increases the rate of endocytic recycling in the prostate tumor cells stably selected for its expression. The working hypothesis is that Hyal1 impacts multiple signaling pathways by modulating the rate of vesicular trafficking, thus contributing to tumor cell growth and motility by maintaining surface presentation of important receptors and by recycling and releasing biologically potent digestion products of HA that serve as signals. Aim 1 will quantify parameters of altered HA uptake resulting from manipulation of HAS and Hyal1, and determine the consequences for motility and invasion. Aim 2 will identify the route(s) by which HA and Hyal1 are endocytosed, and their fate after uptake. Aim 3 will directly characterize receptor turnover rates in response to HAS or Hyal1 alteration.