Tumor-associated redox state in metastatic colorectal cancer

The high incidence of recurrence and metastasizing in colorectal cancer (CRC) poses the challenge for the improvement in long-term treatment outcome. To determine the major indicators of redox-formative molecules in the tissue of metastatic CRC (mCRC), stages Т2-4N0-2M0G2-3, namely the rate of superoxide radical (SR) generation, nitric oxide (NO) content, the activity of matrix metalloproteinases (MMP), lactoferrin (LF) content, and "free" iron and their association with some clinical and pathological characteristics of the patients. mCRC samples from 51 patients were analyzed (stage II, 31 patients; stage III, 20 patients). The LF and "free" iron were assessed by electron paramagnetic resonance (EPR) at the temperature of 77 °K. The rate of SR and NO generation was determined with spin traps (ТЕМРО-Н, diethyl dithiocarbamate). The activity of MMP-2 and -9 was measured by gelatin zymography using SDS-polyacrylamide gel electrophoresis. Ki-67 expression was analyzed by immunofluorescence technique. In tumors with metastases into the regional lymph nodes (N1-2 category), SR generation rate was 2.2-fold higher than in the tumors categorized as N0. In G3 mCRC, SR generation rate was 1.7-fold higher than in G2-tumors (p < 0.05). The rate of SR generation correlated inversely with differentiation grade of the tumor (r=-0.61; p < 0.05). MMP-2 and -9 activities in mCRC tissue correlated with SR generation rate and NO level (r = 0.44 ÷ 0.53, p < 0.05). The direct correlation between LF content and the stage of the disease (r = 0.42) and "free" iron content (r = 0.61) was demonstrated while the correlation between LF content and tumor differentiation grade was inverse (r = -0.57; p < 0.05). The altered tumor-associated redox state in mCRC tissue contributes to the increased cell proliferation and formation of aggressive phenotype of the tumor. The assays for the content of redox-formative components in mCRC may be used as additional prognostic markers of the course of the disease in CRC patients.