Metastasis is a major cause of death in cancer patients. We report here the use of a multiplex proteomic analysis approach to in vitro and in vivo identify biomarkers involved in melanoma invasion/metastasis. An in vitro quantitative profile of the secretome (>200 proteins) was done on non-metastatic melanoma cell lines (A375, LH, M14, DM.6, Lox, and WUmel19) and their metastatic RhoC-expressing counterparts (A375-RhoC, LH-RhoC, M14-RhoC, DM.6-RhoC, Lox-RhoC, and WUmel19-RhoC). A heat map cluster analysis was performed to characterize protein expression levels on metastatic vs. the non-metastatic melanoma cells and identify secreted markers with significantly altered expression that may be involved in tumor invasion, angiogenesis, and metastasis. An in vivo characterization, using an animal model of human melanoma pulmonary metastasis, has identified differential expression of tissue and circulating protein biomarkers in tumor and sera, respectively. Moreover, use of species-specific assays has allowed us to dissect the contribution of stroma (mouse) and tumor (human). Increased expression of a panel of markers, including IL-8, PLGF, FGF-2, follistatin, MMP-1, MMP-9, TIMP-1, TIMP-2, GDF15, NSE, OPN, and MIF was detected in vivo in both tumor and sera, indicating their roles in inducing angiogenesis, tumor invasion and metastasis. Cell signaling pathway multiplex analyses revealed the activation of PI3K/mTOR pathway in the tumor. Elevated levels of phosphorylated targets of PI3K/mTOR pathway, p70S6K (pT412), GSK3α (pS21), GSK3β (pS9), RPS6 (pS235/236), TSC2 (pS939) and mTOR (pS2448) were detected in the pulmonary tumor metastasis. Hence this human melanoma pulmonary metastasis model may prove to be a useful animal model for studying the actions of PI3K/mTOR inhibitors in melanoma metastasis. Altogether, these in vitro and in vivo studies using multiplex proteomic analysis may assist in the discovery of biomarkers and therapeutic targets for human melanoma interventions.

Citation Format: Wen-Rong Lie, Michelle Becker-Hapak, Megan Chan, James Graham, Jehangir Mistry, Gerald Linette, Beatriz Carreno. In vitro and in vivo characterization of protein biomarkers of metastasis in melanoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 409. doi:10.1158/1538-7445.AM2013-409