Avaliação dos níveis de antioxidantes não enzimáticos em pacientes com adenocarcinoma colorretal esporádico

Abstract

Colorectal cancer (CRC) has become one of the most commonly diagnosed neoplastic diseases in Brazil and worldwide. Estimates show that in Brazil, in 2020, about 40 thousand new cases of CRC will be diagnosed, data that characterize this neoplasm as a public health problem. It is estimated that in 80% of diagnoses, CRC is sporadic and this high incidence is strongly correlated with eating habits, especially factors such as the consumption of red meat and embedded foods, and alcoholic beverages. Studies have revealed that oxidative stress is closely associated with the development and progression of neoplasms, being extremely relevant to evaluate these aspects of cellular functions in a group of patients with sporadic CRC. The objective of this study was to evaluate the non-enzymatic antioxidant profile, by measuring the content of total thiols (T-SH) and non-protein thiols (NPSH) in the serum, in addition to the levels of vitamin C (VIT C) in the plasma of a group of patients diagnosed with CRC of the histological subtype adenocarcinoma. To carry out the research, 12 mL of blood were collected by venipuncture in 19 patients diagnosed with CRC. The collection of biological material occurred prior to surgical removal of the tumor, or any other treatment, and the patients involved in the study did not have a family history of the disease. The control group was composed of 10 healthy individuals, of the same gender and equivalent age as the patient group. To determine the T-SH and NPSH groups in serum, the method described by Elmann (1959) was used and for the measurement of VIT C in plasma, the methodology described by Jacques-Silva et al. (2001). For statistical analysis, the data were first tested for normality, and subjected to statistical treatment using the Student's t-test. The level of significance used was P<0.05. Of the three markers analyzed, only the values of T-SH were significantly different between the group of patients (4.73 ± 0.27) and the control group (3.84 ± 0.26) (P<0.05). The depletion of serum T-SH levels in patients with CRC is strongly associated with the consumption of these components to neutralize oxygen reactive species (ROS), so that oxidative stress is controlled and the carcinogenic process does not progress further. In addition, the reduced levels of T-SH and the levels of NPSH within the normal range may be fundamental for the success of the antineoplastic therapeutic protocol, considering that high levels of T-SH, as well as NPSH, are linked to resistance to antineoplastic chemotherapy drugs. Furthermore, the maintenance of VIT C levels similar to that of the control group makes evident the preventive action of this antioxidant on the deleterious actions of excess ROS in the circulation of patients with cancer. For all these reasons, the assessment of serum levels of these antioxidant molecules is of fundamental relevance for a better understanding of the pathophysiology of CRC and for proposing interventions that may be beneficial for these patients.