Aim: To study the redox-dependent mechanism of antiradical, antitumor and antimetastatic action of L-arginine hydrochloride (L-Arg) and coenzyme Q10 (CoQ10) in vivo.
Materials and methods: The study was performed on С(57)Вl mice with transplanted Lewis lung carcinoma treated by intraperitoneal injections of L-Arg at low or high doses (60 and 360 mg/kg body weight), CoQ10 (0.2 and 1.2 mg/kg body weight) or their combinations. Electron paramagnetic resonance was applied for analysis of mitochondrial electron transport chain, СoQ10 levels, free iron (FI), the level of NO, and the rate of superoxide radical generation. The activity of matrix metalloproteinase (MMP)-2 and -9 in tumor tissue was determined by zymography method in polyacrylamide gel.
Results: Administration of L-Arg at high doses caused an inhibition of tumor growth by 48 ± 8.0%, increase of superoxide radical generation rate and NO levels to a value of 1.23 ± 0.14 and 2.26 ± 0.31 nm/g tissue · min, and decreased activity of MMP-2 and -9 (3.55 ± 0.8 and 4.8 ± 1.0 r.u., respectively). Treatment with L-Arg at low doses stimulated tumor growth and increased the levels of MMP-2 and -9 activities (8.44 ± 2.7 and 9.8 ± 3.1 r.u., respectively). Administration of СoQ10 at high doses significantly decreased superoxide radical generation rate to the values of 0.44 ± 0.09 nm/g tissue · min, levels of free iron and NO, and caused tumor growth inhibition by 54 ± 11.3%. The combined use of L-Arg and СoQ10 at high doses caused tumor growth inhibition by 51 ± 7.4% compared to Lewis lung carcinoma-bearing untreated animals (p<0.05).
Conclusions: Administration of L-Arg and СoQ10 caused the dose-dependent effect on the rate of generation of superoxide radicals, level of ubisemyquinone, complexes NOFeS-proteins, levels of FI and NO. L-Arg at low doses positively modulated MMP-9 activity that promoted tumor progression. Upon combined use of L-Arg and СoQ10, superoxide radicals and NO form the redox state that causes decrease of MMP-2, -9 activities with consequent inhibition of tumor invasion and metastasis.