It is estimated that there will be 140,430 new diagnoses of urogenital cancers and 30,000 associated deaths in 2013. Metastatic progression is the primary cause of cancer-related death. Managing care for cancer patients with progressive disease is an arduous challenge and poses an increasing financial burden on our medical institutions. Therefore, is imperative that we elucidate the molecular mechanisms that drive metastasis and identify clinical biomarkers that can specifically recognize invasive disease and rapidly assess therapeutic response. Fluid-based biomarkers are ideal for disease surveillance and therapeutic monitoring because they allow for non-invasive, repetitive sampling. The clinical impact of such a biomarker would be multifaceted by reducing healthcare costs, reducing toxicities associated with ineffective drugs, and improving the implementation of drug trials. In summary, successful implementation of active monitoring for recurrence and rapid identification of treatment response is synonymous with reducing morbidity, mortality, and the associated health care cost.
Knowledge and understanding of molecular changes that drive cancer progression and metastasis can be used both to develop targets for clinical intervention and to detect this progression prior to overt clinical manifestation. In particular, biomarkers that monitor disease progression and assess response to treatment can greatly improve clinical intervention and patient outcome. Such biomarkers are increasingly implemented for disease surveillance and monitoring treatment response and are referred to as 'companion diagnostics.' Since changes in cell adhesion and migration are critical to malignant dissemination and metastasis, it is reasonable to expect molecular mechanisms that support tumor cell motility are desirable therapeutic targets and promising indicators of molecular progression of cancer. We have identified Activated Leukocyte Cell Adhesion Molecule (ALCAM) as an important regulator of tumor cell motility and metastasis in both pre-clinical and mechanistic studies. We have demonstrated that ALCAM is a critical contributor to tumor cell metastasis. By analyzing ALCAM in the serum of tumor-bearing animals, we demonstrated that shedding of the extracellular domain of ALCAM corresponds to disease progression and tumor burden. Furthermore, we found significantly elevated ALCAM levels in both the urine and serum of patients with renal (RCC) and bladder (BCa) cancer. Based on our preliminary studies, we hypothesize that the proteolytic shedding of ALCAM contributes to disease progression and that 'shed' ALCAM is a biomarker of disease progression, as well as treatment response in urogenital cancers. The value of shed ALCAM as a biomarker is two-fold: 1) It is a mechanistic link to tumor cell migration and, subsequently, able to report on 'invasive' disease rather than merely the presence of cancer, and 2) The non-invasive detection of ALCAM in urine and serum offers longitudinal assessment of treatment response and disease progression. In addition, understanding how proteolytic processing of ALCAM contributes mechanistically to disease progression will reveal therapeutic approaches that can intervene in the malignant dissemination of cancer. We will address the following Specific Aims: 1. Determine the utility of shed ALCAM in monitoring recurrence and therapeutic response in patients with urogenital cancer. ALCAM is shed into adjacent biofluids such as blood and urine where its levels correlate with tumor burden and disease progression. If this biomarker can be used to accurately monitor patients with existing disease and report on the response to therapy, it can be used to guide clinical care in cancer patients. 2. Determine the mechanism by which ALCAM shedding contributes to the metastatic progression of BCa using a structure/function analysis. ALCAM is cleaved by two proteases, ADAM17 and ?-secretase, which results in the release of an extracellular (ECD) and intracellular (ICD) domain, respectively. Preliminary data in our laboratory suggests that these two ALCAM domains independently regulate cell adhesion, migration and survival differently from the intact protein. To elucidate the function of each domain in regards to tumor cell survival and migration, we will express 7 ALCAM constructs lacking the ECD, ICD and/or the transmembrane domain in bladder cancer cell lines and assess tumor cell survival, invasion, and metastasis in vitro and in vivo. 3. Identify the ADAM-mediated 'sheddome' of invasive BCa. The promiscuity of membrane proteases such as ADAMs and their established participation in tumor cell invasion suggests that identification of the ADAM-mediated 'sheddome' of invasive/metastatic bladder cancer would substantially contribute to the understanding of the mechanism of metastatic progression and provide additional fluid-based prognostic biomarkers that can be validated with cohorts from Aim 1. We will collect surface biotinylated proteins and utilized a targeted proteomics approach to identify those transmembrane proteins targeted by the ADAM family of proteases. Comparison across a panel of non-invasive verses invasive bladder cancer cell lines will identify the surface proteins shed by ADAMs in response to malignant progression.
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