The prognosis for patients with melanoma is directly related to the depth of invasion of the primary lesion at the time of diagnosis. Thus, when diagnosed at an early stage, the patient is often cured by a wide and deep excision of the melanoma. However, once primary melanoma metastasizes to different sites, the prognosis is grave because metastatic melanoma is refractory to conventional therapy. Based upon the finding that compared to melanoma precursor lesions, primary and metastatic human melanomas, and cell lines established from advanced-stage human melanoma specimens, express high levels of the cell adhesion molecules N-cadherin, M-CAM, and beta3 integrin, we postulate that these three genes/proteins, alone or in concert, play important roles in melanoma cell invasion and formation of metastases. To test this hypothesis, we propose to combine antisense gene targeting and optical bioimaging to determine, in vivo, whether these three adhesion molecules govern melanoma cell adhesion, invasion, and metastasis formation. To obtain an answer for this important but unanswered question, primary human melanomas, grown as subcutaneous tumors in nude mice, will be injected, alone and in combination, with vector constructs generating N-cadherin, M-CAM, and/or beta3 integrin antisense transcripts under the control of the human tyrosinase promoter, which is only expressed in human melanoma cells. The tumors will then be injected with different cyanine fluorochrome-conjugated antibodies specific for human N-cadherin, M-CAM, beta3 integrin, and the S100 human melanoma cell surface antigen. Thereupon, non-invasive, macroscopic Spectral Imaging will be performed to document, in vivo, possible loss of cell-cell and cell-stroma interactions in the antisense-targeted melanomas, none of which should be observed in non-targeted control tumors. Following the in vivo imaging analyses of the melanomas, the animals will be sacrificed and tissue sections of their resected tumors and different organs of the nude mice will be subjected to qualitative and quantitative microscopic Spectral Imaging. These ex vivo optical imaging analyses are expected to substantiate the dynamic intratumoral changes captured in vivo, and to provide important information regarding absence versus presence of melanoma metastases in the lungs, abdomen, and brain of mice that carded the antisense-targeted tumors compared to mice that carded the non-targeted tumors.
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