Dicarbonyl-mediated protein modifications affect matrix metalloproteinase (MMP) activity

Do all roads lead to the Rome? The glycation perspective!

Oxidative, carbonyl, and glycative stress have gained substantial attention recently for their alleged influence on cancer progression. Oxidative stress can trigger variable transcription factors, such as nuclear factor erythroid-2-related factor (Nrf2), nuclear factor kappa B (NF-κB), protein-53 (p-53), activating protein-1 (AP-1), hypoxia-inducible factor-1α (HIF-1α), β-catenin/Wnt and peroxisome proliferator-activated receptor-γ (PPAR-γ). Activated transcription factors can lead to approximately 500 different alterations in gene expression, and can alter expression patterns of inflammatory cytokines, growth factors, regulatory cell cycle molecules, and anti-inflammatory molecules. These alterations of gene expression can induce a normal cell to become a tumor cell. Glycative stress resulting from advanced glycation end products (AGEs) and reactive dicarbonyls can significantly affect cancer progression. AGEs are fashioned from the multifaceted chemical reaction of reducing sugars with a compound containing an amino group. AGEs bind to and trigger the receptor for AGEs (RAGE) through AGE-RAGE interaction, which is a major modulator of inflammation allied tumors. Dicarbonyls like, GO (glyoxal), MG (methylglyoxal) and 3-DG (3-deoxyglucosone) fashioned throughout lipid peroxidation, glycolysis, and protein degradation are viewed as key precursors of AGEs. These dicarbonyls lead to the carbonyl stress in living organisms, possibly resulting in carbonyl impairment of proteins, carbohydrates, DNA, and lipoproteins. The damage caused by carbonyls results in numerous lesions, some of which are involved in cancer pathogenesis. In this review, the effects of oxidative, carbonyl and glycative stress on cancer initiation and progression are thoroughly discussed, including probable signaling pathways and the effects on tumorigenesis.

Prognostic potential and tumor growth-inhibiting effect of plasma advanced glycation end products in non-small cell lung carcinoma

The plasma fluorescence related to the standard fluorescence of advanced glycation end products (AGEs) is a simple measurable blood parameter for distinct diseases but its importance in human cancer, including non-small cell lung carcinoma (NSCLC), is unknown. Plasma samples of 70 NSCLC patients who underwent resection surgery of the tumor were analyzed for the distinct AGE-related fluorescence at 370 nm excitation/440 nm emission. In a retrospective study, we tested the prognostic relevance of this AGE-related plasma fluorescence. The effect of circulating AGEs on the NSCLC growth was studied experimentally in vitro and in vivo. NSCLC patients with high (> median) AGE-related plasma fluorescence were characterized by a later reoccurrence of the tumor after curative surgery and a higher survival rate compared with patients with low plasma fluorescence (25% versus 47% 5-y survival, P = 0.011). Treating NSCLC cell spheroids with patients' plasma showed an inverse correlation between the growth of spheroids in vitro and the individual AGE-related fluorescence of each plasma sample. To confirm the impact of circulating AGEs on the NSCLC progression, we studied the NSCLC growth in mice whose circulating AGE level was elevated by AGE-rich diet. In vivo tumorigenicity assays demonstrated that mice with higher levels of circulating AGEs developed smaller tumors than mice with normal AGE levels. The AGE-related plasma fluorescence has prognostic relevance for NSCLC patients in whom the tumor growth-inhibiting effect of circulating AGEs might play a critical role.