The association between trace metals in both cancerous and non-cancerous tissues with the risk of liver and gastric cancer progression in northwest China

Liver cancer and gastric cancer have extremely high morbidity and mortality rates worldwide. It is well known that an increase or decrease in trace metals may be associated with the formation and development of a variety of diseases, including cancer. Therefore, this study aimed to evaluate the contents of aluminium (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), selenium (Se), and zinc (Zn) in cancerous liver and gastric tissues, compared to adjacent healthy tissues, and to investigate the relationship between trace metals and cancer progression. During surgery, multiple samples were taken from the cancerous and adjacent healthy tissues of patients with liver and gastric cancer, and trace metal levels within these samples were analysed using inductively coupled plasma mass spectrometry (ICP-MS). We found that concentrations of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, and Zn in tissues from patients with liver cancer were significantly lower than those in healthy controls (P < 0.05). Similarly, patients with gastric cancer also showed lower levels of Cd, Co, Cr, Mn, Ni, and Zn-but higher levels of Cu and Se-compared to the controls (P < 0.05). In addition, patients with liver and gastric cancers who had poorly differentiated tumours and positive lymph node metastases showed lower levels of trace metals (P < 0.05), although no significant changes in their concentrations were observed to correlate with sex, age, or body mass index (BMI). Logistic regression, principal component analysis (PCA), Bayesian kernel regression (BKMR), weighted quantile sum (WQS) regression, and quantile-based g computing (qgcomp) models were used to analyse the relationships between trace metal concentrations in liver and gastric cancer tissues and the progression of these cancers. We found that single or mixed trace metal levels were negatively associated with poor differentiation and lymph node metastasis in both liver and gastric cancer, and the posterior inclusion probability (PIP) of each metal showed that Cd contributed the most to poor differentiation and lymph node metastasis in both liver and gastric cancer (all PIP = 1.000). These data help to clarify the relationship between changes in trace metal levels in cancerous liver and gastric tissues and the progression of these cancers. Further research is warranted, however, to fully elucidate the mechanisms and causations underlying these findings.

Approaches and Methods to Measure Oxidative Stress in Clinical Samples: Research Applications in the Cancer Field

Reactive oxygen species (ROS) are common by-products of normal aerobic cellular metabolism and play important physiological roles in intracellular cell signaling and homeostasis. The human body is equipped with antioxidant systems to regulate the levels of these free radicals and maintain proper physiological function. However, a condition known as oxidative stress (OS) occurs, when ROS overwhelm the body's ability to readily detoxify them. Excessive amounts of free radicals generated under OS conditions cause oxidative damage to proteins, lipids, and nucleic acids, severely compromising cell health and contributing to disease development, including cancer. Biomarkers of OS can therefore be exploited as important tools in the assessment of disease status in humans. In the present review, we discuss different approaches used for the evaluation of OS in clinical samples. The described methods are limited in their ability to reflect on OS only partially, revealing the need of more integrative approaches examining both pro- and antioxidant reactions with higher sensitivity to physiological/pathological alternations. We also provide an overview of recent findings of OS in patients with different types of cancer. Identification of OS biomarkers in clinical samples of cancer patients and defining their roles in carcinogenesis hold great promise in promoting the development of targeted therapeutic approaches and diagnostic strategies assessing disease status. However, considerable data variability across laboratories makes it difficult to draw general conclusions on the significance of these OS biomarkers. To our knowledge, no adequate comparison has yet been performed between different biomarkers and the methodologies used to measure them, making it difficult to conduct a meta-analysis of findings from different groups. A critical evaluation and adaptation of proposed methodologies available in the literature should therefore be undertaken, to enable the investigators to choose the most suitable procedure for each chosen biomarker.

Serum and whole blood Zn, Cu and Mn profiles and their relation to redox status in lung cancer patients

Disturbed redox status may be critical to lung cancerogenesis, however little research has been conducted on general changes in total redox status in lung cancer. Levels and activities of antioxidants, especially enzymatic ones, are related to trace element concentration. Trace element status is often disturbed in cancers, however no studies concerning the association between redox and trace element status have been performed for lung cancer. We hypothesized that disturbed redox status in lung cancer patients is partially determined by trace elements while their distribution amongst blood compartments may differ compared to healthy subjects. Blood samples from lung cancer patients (n=44) and control subjects (n=44) were collected to assess redox and trace element status. Serum and whole blood Cu and Mn levels were determined with GF-AAS, and Zn-with F-AAS. In serum the total antioxidant status (TAS) was determined with the commercial kit TAS (Randox, UK), total oxidant status (TOS) was determined based on the method developed by Erel and the oxidative stress index (OSI) was calculated. Total protein (T-Prot), albumin (Alb), uric acid (UA) and total bilirubin (T-Bil) concentrations were measured with an auto-analyser (Konelab 20i, Thermoscientific, USA), SOD and CAT activity - with commercially available kits (Cayman, USA). The level of TAS, T-Prot, Alb, T-Bil, the activity of SOD, the concentration of whole blood Mn as well as serum and whole blood Zn were lower while TOS, OSI, serum Cu levels and serum Cu:Zn ratios were higher in lung cancer patients compared to the control group. In the lung cancer group TAS correlated positively with Alb and UA, serum Zn and negatively with whole blood Mn. Additionally, SOD positively correlated with the whole blood Mn and Cu:Zn ratio, while CAT - negatively with the whole blood Cu:Zn ratio. In the lung cancer sub-group at clinical stage I-II, TOS additionally negatively correlated with whole blood Zn, and CAT negatively with serum Cu and Cu:Zn ratio. In advanced lung cancer, we found a positive correlation between TAS and serum Zn, and a negative one - with serum Cu:Zn ratio. We observed a similar correlation between endogenous non-enzymatic antioxidants and TAS in the control group, however considerably fewer correlations between trace elements and antioxidants were observed. This study supports the hypothesis that disturbed redox status in lung cancer patients is linked with alterations in trace element status regarding Zn, Mn and Cu. Moreover, the type of biological fluid influences both - alterations in the metal profile and relationships with redox status parameters.