Proteomic and SAGE profiling of murine melanoma progression indicates the reduction of proteins responsible for ROS degradation

Abstract

Using 2-DE of total cell protein extracts, we compared soluble proteins from murine melanoma lines Tm1 and Tm5 with proteins from the nontumoral cell melan-a from which they were derived. Seventy-one of the 452 spots (average) detected with CBB were differentially accumulated, i.e., increased or decreased twofold. Forty-four spots were identified by PMF/MALDI-TOF, 15 with increased and 29 with decreased protein levels. SAGE showed that 17/34 (50%) of the differentially accumulated proteins, pI range 4-7, presented similar differences at the mRNA level. Major reductions in protein were observed in tumor cells of proteins that degrade reactive oxygen species (ROS). Decreases of > or = twofold in GST, superoxide dismutase, aldehyde dehydrogenase, thioredoxin, peroxiredoxin 2, and peroxiredoxin 6 protein were observed. SAGE indicated the reduction of other proteins involved in ROS degradation. As expected, the accumulation of exogenous peroxides was significantly higher in the tumor cells while the levels of glutathionylation were two times lower in the tumor cells compared to melan-a. The differential accumulation of proteins involved in oncogene/tumor suppressor pathways was observed. Melanoma cells can favor survival pathways activated by ROS by inhibiting p53 pathways and activation of Ras and c-myc pathways.

N-Acetylcysteine Protects Melanocytes against Oxidative Stress/Damage and Delays Onset of Ultraviolet-Induced Melanoma in Mice

“…Melanocytes are particularly sensitive to oxidative stress (7), which is chronically generated during melanogenesis (8) due to the pro-oxidant effect of melanin (9). Melanoma tissues exhibit increased products of lipid peroxidation and levels of antioxidant enzymes compared with benign nevi (10), and oxidative dysregulation is correlated with melanoma progression in a mouse model (11). These observations support the notion that UV-induced oxidative stress/damage contributes to melanoma pathogenesis (12) and could be targeted using antioxidant preventive therapy.…”

“…Thus, overcoming this extreme tendency toward the development of melanocytic tumors would require particularly robust protection. Second, although there is evidence that oxidative stress is pathogenic in the development of melanoma (11,12), there are clearly additional pathways such as oxidation-independent UV-induced DNA damage (indicated by formation of CPDs) that we found were unaffected by NAC. In addition, other UV-induced pathways leading to cell cycle deregulation and modulation of apoptosis resistance may contribute to melanoma in this model and not be amenable to protection by NAC.…”

Specifying protein kinase C functions in melanoma

“…PKCb is activated in response to oxidative stress, which is produced by UV radiation and is elevated in melanoma because of oncogene activation (e.g., BRAF) (de Souza et al, 2006;Fried and Arbiser, 2008;Govindarajan et al, 2007;Meyskens et al, 2001;Zaidi et al, 2008). Elevated reactive oxygen species (ROS) are also produced in response to PKCb activation because of the phosphorylation of p66Shc and activation of the mitochondrial permeability pore, resulting in a positive feedback involving PKCb activation and ROS generation (DelCarlo and Loeser, 2006;Giorgio et al, 2005;Pinton et al, 2007;Voris et al, 2010).…”

Peroxiredoxin-2 Represses Melanoma Metastasis by Increasing E-Cadherin/β-Catenin Complexes in Adherens Junctions

“…Among these enzymes, Prx is the most abundant enzyme and is known to be involved in receptor tyrosine kinase-mediated signal transduction (12). Interestingly, it has recently been shown that one of the Prx family members Prx2 (gene loci, PRDX2), which belongs to 2-cys Prx subfamily and reduces the peroxides in the presence of NADPH by coupling with thioredoxin/thioredoxin reductase system, is downregulated in melanoma cell lines and particularly in metastatic malignant types (13,14). However, the function of the Prx2 enzyme in the melanoma cell growth and metastasis remains unknown.…”