"Life is an instantaneous encounter of circulating matter and flowing energy" (Jean Giaja, Serbian physiologist), is one of the most elegant definitions not only of life but the relationship of redox biology and metabolism. Their evolutionary liaison has created inseparable yet dynamic homeostasis in health, which, when disrupted, leads to disease. This interconnection is even more pertinent today, in an era of increasing metabolic diseases of epidemic proportions such as obesity, metabolic syndrome, and diabetes. Despite great advances in understanding the molecular mechanisms of redox and metabolic regulation, we face significant challenges in preventing, diagnosing, and treating metabolic diseases. The etiological association and temporal overlap of these syndromes present significant challenges for the discrimination of appropriate clinical biomarkers for diagnosis, treatment, and outcome prediction. These multifactorial, multiorgan metabolic syndromes with complex etiopathogenic mechanisms are accompanied by disturbed redox equilibrium in target tissues and circulation. Free radicals and reactive species are considered both a causal factor and a consequence of disease status. Thus, determining the subtypes and levels of free radicals and reactive species, oxidatively damaged biomolecules (lipids, proteins, and nucleic acids) and antioxidant defense components as well as redox-sensitive transcription factors and fluxes of redox-dependent metabolic pathways will help define existing and establish novel redox biomarkers for stratifying metabolic diseases. This review aims to discuss diverse redox/metabolic aspects in obesity, metabolic syndrome, and diabetes, with the imperative to help establish a platform for emerging and future redox-metabolic biomarkers research in precision medicine. Future research warrants detailed investigations into the status of redox biomarkers in healthy subjects and patients, including the use of emerging 'omic' profiling technologies (e.g., redox proteomes, lipidomes, metabolomes, and transcriptomes), taking into account the influence of lifestyle (diet, physical activity, sleep, work patterns) as well as circadian ~24h fluctuations in circulatory factors and metabolites.

Background. Semen analysis is the cornerstone in the evaluation of male (in)fertility. However, there are men with normal semen tests but with impaired fertilizing ability, as well as fertile men with poor sperm characteristics. Thus, there is rising interest to find novel parameters that will help to predict and define the functional capacity of spermatozoa.Methods. We examined whether there is a correlation between semen parameters (count, progressive motility, and morphology) and protein expression/activity of antioxidative defense enzymes in seminal plasma from 10 normospermic subjects.Results. Sperm progressive motility was in positive correlation with seminal plasma protein expression of both superoxide dismutase (SOD) isoforms (MnSOD and CuZnSOD) and catalase. Also, positive correlation was observed between sperm count and MnSOD protein expression, as well as between sperm morphology and protein expression of catalase in seminal plasma. In contrast, protein expression of glutathione peroxidase was not in correlation with any sperm parameter, while its activity negatively correlated with sperm morphology and motility.Conclusions. These data suggest that evaluation of protein expression of antioxidative defense enzymes in seminal plasma might be of importance in the evaluation of male fertility status and that could be used as an additional biomarker along with classic semen analysis in assessment of semen quality.

Introduction: Metabolic syndrome arises from abnormal adipose function accompanied by insulin resistance. As early factors reflecting/impacting lipid storage dysfunction of adipose tissues, we sought to determine adipokine levels in subcutaneous and visceral adipose tissues (SAT and VAT).Material and methods: Gene and protein expression of leptin, adiponectin, and resistin were analyzed in SAT and VAT of normal-weight and overweight/obese women, subclassified according to insulin resistance index, triglyceride, total-, LDL- and HDL-cholesterol levels into metabolically healthy and “at risk” groups.Results: Compared with normal-weight women, obese women had higher serum leptin levels (P<0.05), as well as increased leptin gene and protein expression in VAT. Conversely, expression levels of leptin were lower in SAT of obese women, and minor in the SAT of “at risk” groups of women, compared with weight-matched healthy groups. In addition, lower adiponectin levels were detected in SAT of metabolically healthy obese women (P<0.01), and lower in SAT and VAT (P<0.05) of “at risk” obese women compared to healthy, obese women. Significant differences in resistin levels were only observed in obese women; resistin gene expression was higher in VAT and SAT of obese, compared to normal-weight women. However, higher gene expression was not consistent with protein expression of resistin.Conclusions: Low adiponectin in both examined adipose tissues and inappropriate leptin expression levels in SAT appear to be important characteristics of obesity-related metabolic syndrome. Intriguingly, this adipokine dysregulation is primary seen in SAT, suggesting that endocrine dysfunction in this abdominal depot may be an early risk sign of metabolic syndrome.

Typical features of the breast malignant phenotype rely on metabolic reprogramming of cancer cells and their interaction with surrounding adipocytes. Obesity is strongly associated with breast cancer mortality, yet the effects of obesity on metabolic reprogramming of cancer and cancer-associated adipose tissue remain largely unknown. Paired biopsies of breast tumor tissue and adipose tissue from premenopausal women were divided according to pathohistological analyses and body mass index on normal-weight and overweight/obese with benign or malignant tumors. We investigated the protein expression of key regulatory enzymes of glycolysis, pentose phosphate pathway (PPP), and glycogen synthesis. Breast cancer tissue showed a simultaneous increase in 5′-AMP-activated protein kinase (AMPK) protein expression with typical features of the Warburg effect, including hexokinase 2 (HK 2) overexpression and its association with mitochondrial voltage-dependent anion-selective channel protein 1, associated with an overexpression of rate-limiting enzymes of glycolysis (phosphofructokinase 1—PFK-1) and pentose phosphate pathway (glucose-6-phosphate dehydrogenase—G6PDH). In parallel, cancer-associated adipose tissue showed increased AMPK protein expression with overexpression of HK 2 and G6PDH in line with increased PPP activity. Moreover, important obesity-associated differences in glucose metabolism were observed in breast cancer tissue showing prominent glycogen deposition and higher glycogen synthase kinase-3 protein expression in normal-weight women and higher PFK-1 and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) protein expression in overweight/obese women. In conclusion, metabolic reprogramming of glycolysis contributes to tissue-specific Warburg effect in breast cancer and cancer-associated adipose tissue.

MiR-21 and miR-375 have been reported as dysregulated in prostate cancer (PCa) in multiple previous studies. Still, variable or even opposing data for the expression of these microRNAs in PCa were found, and their potential biomarker properties remain elusive. In an attempt to clarify their significance as PCa biomarkers, as well as to compare different types of specimens as a source of relevant microRNAs, we used plasma and matching plasma-derived exosomes from patients with PCa and patients with benign prostatic hyperplasia (BPH). Plasma and exosomes were obtained from 34 patients with PCa and 34 patients with BPH, and their levels of expression of miR-21 and miR-375 were determined by RT-qPCR. We found no significant difference in the level of expression of these microRNAs in plasma and exosomes between patients with PCa and BPH. The level of exosomal miR-21 was elevated in PCa patients with high serum PSA values, as well as in patients with aggressive PCa, while for plasma samples, the results remained insignificant. For miR-375, we did not find an association with the values of standard prognostic parameters of PCa, nor with cancer aggressiveness. Therefore, our results support the potential prognostic role of exosomal miR-21 expression levels in PCa.

Metabolic reprogramming that favors high glycolytic flux with lactate production in normoxia is among cancer hallmarks. Lactate is an essential oncometabolite regulating cellular redox homeostasis, energy substrate partitioning, and intracellular signaling. Moreover, malignant phenotype’s chief characteristics are dependent on the interaction between cancer cells and their microenvironment. In breast cancer, mammary adipocytes represent an essential cellular component of the tumor milieu. We analyzed lactate concentration, lactate dehydrogenase (LDH) activity, and isozyme pattern, and LDHA/LDHB protein expression and tissue localization in paired biopsies of breast cancer tissue and cancer-associated adipose tissue in normal-weight and overweight/obese premenopausal women, compared to benign breast tumor tissue and adipose tissue in normal-weight and overweight/obese premenopausal women. We show that higher lactate concentration in cancer tissue is concomitant with a shift in isozyme pattern towards the “muscle-type” LDH and corresponding LDHA and LDHB protein expression changes. In contrast, significantly higher LDH activity in cancer-associated adipose tissue seems to be directed towards lactate oxidation. Moreover, localization patterns of LDH isoforms varied substantially across different areas of breast cancer tissue. Invasive front of the tumor showed cell-specific protein localization of LDHA in breast cancer cells and LDHB in cancer-associated adipocytes. The results suggest a specific, lactate-centric relationship between cancer tissue and cancer-associated adipose tissue and indicate how cancer-adipose tissue cross-talk may be influenced by obesity in premenopausal women.