A high proliferation rate and the malignancy of cancer cells are favoured by redox and metabolic plasticity, which is determined by the co-evolution of cancer cells with their host microenvironment. The tight functional connections between the mammary glands' epithelium and adipose tissue (AT) allow breast cancer cells to subjugate the AT and form a protumorigenic cancer-associated adipose tissue (CAAT). Our findings in luminal invasive ductal carcinomas in premenopausal women confirmed key cancer cell strategies - the Warburg effect, increased mitochondrial metabolism and redox adaptability, which are associated with a specific shift in the metabolic and redox phenotype of CAAT. Notably, the upregulated master redox-sensitive transcription factor Nrf2 appears to be responsible for the cancer cell-induced redox and metabolic shift of CAAT. We also investigated the role of Nrf2 in the metabolic co-evolution of cancer cells and CAAT during disease progression. Our results in the orthotopic breast cancer mouse model and in the co-culture of breast cancer cells with adipocytes confirmed the different spatiotemporal redox and metabolic properties of cancer cells and CAAT, established with respect to the Nrf2-coupled/uncoupled tumour microenvironment. The uncovered metabolic and redox strategies adopted by breast cancer cells according to CAAT properties and at different disease stages have helped to better understand the biology of the aggressive disease and to identify breast cancer vulnerabilities that could become therapeutic targets.

This research was supported by the Science Fund of the Republic of Serbia, #7750238, Exploring new avenues in breast cancer research: Redox and metabolic reprogramming of cancer and associated adipose tissue - REFRAME.

Since the discovery of the thermogenic role of brown adipocytes, there was consensus that the biochemical and metabolic function of their mitochondria is uniform. By switching the ATP production between glycolytic pathway and oxidative phosphorylation, brown adipocytes are able to produce heat in mitochondria through uncoupling protein 1 (UCP1). Thermogenically active brown adipocyte mitochondria are characterized by clear morphological features (long, tightly packed cristae). The process of their biogenesis includes an increased number of mitochondria (by division), increase of their surface area, and incorporation of UCP1 as well as specific structural organization of the cristae. But, is it true that all BA mitochondria within one cell are structurally and functionally the same? Do they harbor the same set of enzymes? Actually, the very first cell mosaicism, e.g. Harlequin appearance was shown in brown adipose tissue. This unique uneven UCP1 expression suggests that brown adipocyte’s mitochondria may be heterogeneous regarding production of ATP (bioenergetic) vs. heat (thermogenic) role. This presentation deals with structural and functional mitochondrial mosaicism and changes caused by insulin.

This research was supported by the Science Fund of the Republic of Serbia, #7750238, Exploring new avenues in breast cancer research: Redox and metabolic reprogramming of cancer and associated adipose tissue - REFRAME.

Aging is a natural process characterized by a decline in organic structure-function and an increase in mortality over time. While many exogenous and endogenous factors contribute to aging, the long-term effects of low environmental temperature have been poorly described. To address this, our study compared 24-month-old male Mill Hill hybrid hooded rats raised at a standard temperature of 22±1°C with age-matched rats that were kept in a cold room (4±1°C) from the age of 6 to 24 months. 3- and 6-month-old rats raised at 22±1°C were included as room temperature controls. We examined two metabolically active organs, interscapular brown adipose tissue (iBAT) and liver. It was found that 24-month-old rats chronically exposed to cold exhibit increased food consumption, which may be attributed to a higher metabolic demand. Chronic exposure of aged rats to low environmental temperature led to an increase in iBAT relative mass, total glutathione (GSH) content, and antioxidant defense (AD) enzyme activity: CuZn superoxide dismutase, Mn superoxide dismutase, catalase, glutathione peroxidase, and thioredoxin reductase. Respirometric analysis further demonstrated an increase in mitochondrial uncoupling in iBAT in 24-month-old rats kept at 4±1°C. Conversely, there was no change of the same parameters in the liver, which maintained consistent AD enzyme activity and GSH content across all experimental groups. Our study confirms that iBAT of aged rats remains responsive to stimulation by low environmental temperature, supporting thermogenic processes through uncoupling and a robust increase in the AD system. These results highlight tissue-specific effects of chronic cold exposure on aged rats underlying acclimation-driven physiological changes.

Breast cancer is characterized by specific metabolic changes that support tumorigenesis, highlighting the emerging appreciation of cancer as a metabolic disease. These metabolic changes are simultaneous with redox reprogramming with nuclear factor erythroid 2-related factor 2 (Nrf2) representing their master integrator. Given that interscapular brown adipose tissue (IBAT) influences whole-body metabolism, our goal was to investigate the redox-metabolic crosstalk between the tumor and the host at the systemic level by exploring Nrf2-driven metabolic changes that occur in IBAT in the orthotopic model of breast cancer in wild-type (WT) and mice lacking functional Nrf2 (Nrf2KO). We analyzed the protein expression of key enzymes involved in glucose and lipid metabolism in control groups and at different points during tumor growth (10 mg, 50 mg, 100 mg, 200 mg, and 400 mg). In both WT and Nrf2KO mice, the results indicated a transient induction of hexokinase 2 expression during the early phase of tumor growth (<100 mg). Accordingly, pyruvate dehydrogenase expression followed the same profile. In Nrf2KO mice, a general decline in glyceraldehyde 3-phosphate dehydrogenase, phosphofructokinase-1, and glucose-6-phosphate dehydrogenase expression was detected during the late phase of tumor growth (>100 mg). Since no changes in WT mice occurred, these findings are considered Nrf2-dependent. Concomitantly, a decrease in protein expression of fatty acid synthase and acetyl-CoA carboxylase in Nrf2KO mice was observed. These observations correspond to decreased levels of 5'-AMP-activated protein kinase and hypoxia-inducible factor 1 during the late-phase (>100 mg) of tumor growth in Nrf2KO mice which suggests their involvement in transcriptional regulation. Our results revealed that IBAT metabolism responds to tumor growth and underscored that this communication is Nrf2-dependent giving implications for further understanding of breast cancer in the light of systemic metabolic disease.

This research was supported by the Science Fund of the Republic of Serbia, #7750238, Exploring new avenues in breast cancer research: Redox and metabolic reprogramming of cancer and associated adipose tissue - REFRAME.

Thyroid hormones play an important role in both testis development and spermatogenesis. While hypothyroidism has been known to generally induce metabolic suppression, lower respiration rate, and reduce free radical formation, recent studies reported an increased production of reactive oxygen species (ROS). First line of antioxidant defense in testes is comprised of two isoforms of superoxide dismutase (SOD), CuZnSOD and MnSOD differently localised in cell. This study aimed to investigate the effects of hypothyroidism on the expression, localisation, and activity of these two SOD isoforms during spermatogenesis. Hypothyroidism was induced in two-month-old male Wistar rats by 0.04% methimazole in drinking water for 7, 15, and 21 days, while euthyroid control group drank tap water. CuZnSOD protein expression was decreased after 15 and 21 days while its activity was decreased by 40% in all examined time points of methimazole treatment in comparison to euthyroid control. At the same time, neither MnSOD protein expression nor its activity was changed by treatment. However, cell and stage-specific CuZnSOD and MnSOD immunoexpression in the rat testes were changed in hypothyroidism and may contribute to the altered spermatic characteristics. Our results suggest that changes in CuZnSOD and MnSOD expression play role in redox disbalance leading to hypothyroidism-induced maturation arrest of spermatogenesis.

Colorectal cancer presents a significant global health challenge, with a high mortality rate. It is the third most commonly diagnosed cancer and is therefore a major cause for concern. The development of colorectal cancer is multifaceted, involving a combination of genetic predispositions and lifestyle factors. The redox and metabolic states may influence the intricate process of colon cancer development. To gain a deeper understanding of the redox-metabolic profiles associated with colon cancer, a human study was conducted. In biopsies from patients with colon cancer, the antioxidant status: copper, zinc superoxide dismutase (CuZnSOD), manganese superoxide dismutase (MnSOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutamate-cysteine ligase (GCL), thioredoxin (Trx) and lactate metabolism were examined in tumor and unaffected colon tissue (remote 15-20 cm) as well as in adipose tissue: proximal (near the tumour tissue), distal (remote 6 cm) and unaffected (remote over 6 cm). The protein levels of CuZnSOD, MnSOD, GSH-Px, and Trx are increased in the tumor tissue compared to the unaffected colon tissue. In addition, the expression of the lactate dehydrogenase (LDH) A isoform, the total activity of LDH and the lactate concentration are higher in transformed tumor tissue than in normal colon tissue. On the other hand, lactate concentration increases and several AD components (CuZnSOD, MnSOD, CAT, GSH-Px, GCL and Trx) decrease in adipose tissue with tumor proximity. Shifts in redox and lactate metabolism in tumor tissue associated with spatial changes in lactate and antioxidant enzymes gradients in adjacent adipose tissue clearly indicate a local redox metabolic interaction between tumor and tumor-associated adipose tissue in shaping the malignant phenotype in human colorectal cancer.

The metastasis of breast cancer to the axillary lymph nodes represents a crucial aspect of disease progression and prognostic evaluation. The presence of metastases in the axillary lymph nodes is a key indicator that breast cancer is in an advanced stage, which can influence the therapeutic approach and the patient's prognosis. For this reason, we conducted a study aimed at examining the factors that contribute to the presence of metastases in lymph nodes in our female population. This research represents a prospective study conducted at the Institute of Oncology of Vojvodina in Sremska Kamenica. The study included 72 female participants diagnosed with breast cancer who underwent surgery at the Institute of Oncology of Vojvodina and had not received preoperative chemotherapy or radiation therapy. Initially, anamnestic data were collected from the participants, followed by a pathohistological analysis of the tumor tissue samples, including immunohistochemical analysis. We examined the influence of age, tumor size, activity of estrogen, progesterone, and HER2 receptors (human epidermal growth factor receptor-2)  in tumors, as well as the occurrence of menarche and breastfeeding duration, on the presence of metastases in axillary lymph nodes. The results of binary logistic regression showed that the only significant predictor for the presence of metastases in axillary lymph nodes was tumor size (p=0.01, Wald=6.57, and Exp(B)=1.11), while the other examined predictors were not statistically significant (p>0.05). In our study population, the size of the breast cancer was crucial for the presence of metastases in the axillary lymph nodes.

This research was supported by the Science Fund of the Republic of Serbia, #7750238, Exploring new avenues in breast cancer research: Redox and metabolic reprogramming of cancer and associated adipose tissue - REFRAME.

Breast cancer is one of the most common malignant diseases in women worldwide. Since the involvement of axillary lymph node metastases is related to the poor prognosis of these patients, the objective of our study was to investigate the association between breast tumor size and the presence of axillary lymph node metastases. Our research was performed at the Institute of Oncology of Vojvodina in Sremska Kamenica. The study consisted of 72 women diagnosed with breast cancer aged between 29 and 84 years (average age: 59.04±10.87 years) whose breast tumor was surgically removed at the Institute of Oncology of Vojvodina. Patients who received preoperative chemo- or radiotherapy were excluded from the study. The data concerning breast tumor size and the presence of axillary lymph nodes in these women was obtained from the reports of Department of Pathoanatomical Diagnostics of the Institute of Oncology of Vojvodina. The results of our study indicated to positive, statistically significant moderate correlation between the size of breast tumor and the presence of axillary lymph node metastases (r=0.32, p=0.01). Receiver operating curve (ROC) analysis notified that cut-off value of breast tumor size for the presence of axillary lymph node metastasis was 22.5 mm (AUC=0.70, p=0.01). In our investigation, women with breast tumor size of 22.5 mm or larger were predisposed to the presence of axillary lymph node metastases.

This research was supported by the Science Fund of the Republic of Serbia, #7750238, Exploring new avenues in breast cancer research: Redox and metabolic reprogramming of cancer and associated adipose tissue - REFRAME.