Changes of reduced glutathione and glutathione S-transferase levels in colorectal cancer patients undergoing treatment.

Abstract

The available data concerning reduced glutathione (GSH) and glutathione S-transferase (GST) levels in colorectal cancer patients during the treatment process are contradictory and insufficient. Forty patients with metastatic colorectal cancer receiving FOLFOX4 chemotherapy with or without bevacizumab and 40 healthy volunteers were included in the study. Blood samples were taken before treatment, after 2 months and at the end of treatment in the patient group and once in the healthy volunteer group. The levels of GSH and GST in blood serum were evaluated by enzyme-linked immunosorbent assay (ELISA) according to the manufacturer's instructions. The serum level of GSH was significantly lower in colorectal cancer patients before treatment than in healthy volunteers (37.84 ± 19.39 μg/mL and 52.78 ± 19.39 μg/mL, respectively; p<0.001). After treatment, the level of GSH increased significantly, while the level of GST decreased significantly. These changes were observed only in the groups of patients with partial or complete response, having metastases only in the liver, receiving FOLFOX4 chemotherapy with bevacizumab, or undergoing resection or radiofrequency ablation of liver metastases. GSH and GST levels change significantly during the treatment process and these changes depend on the response to treatment, treatment type, and site of metastases. Further analysis of the changes in GSH and GST levels during treatment would allow the assessment of the predictive potential of this molecular marker.