Effect of the new matrix metalloproteinase inhibitor RO-28-2653 on mitochondrial function

Matrix metalloproteinases (MMPs) have recently become interesting as potential anticancer drugs. RO-28-2653 is a promising compound because of its antimetastatic and antiangiogenic activities. Due to the structural similarity of RO-28-2653 to mitochondriotoxic agents, speculation has arisen that this substance might impair mitochondrial function. We, therefore, investigated the effects of RO-28-2653 on mitochondrial enzymes and on the functional properties of isolated mitochondria and skinned muscle fibers from rat hearts. Results were compared to the action of amytal and 2,4-dinitrophenol (2,4-DNP), both of which are well documented mitochondriotoxic compounds. In contrast to 2,4-DNP, RO-28-2653 did not uncouple oxidative phosphorylation, although higher concentrations of the compound did impair mitochondrial function. Using malate/pyruvate as substrate, 50 muM of RO-28-2653 inhibited mitochondrial respiration in isolated mitochondria and skinned fibers by 23 and 11 %, respectively while 2 mM of amytal elicited almost complete inhibition of the mitochondrial respiration. RO-28-2653 (50 muM) inhibited succinate-dependent respiration in both systems by 43 and 24%, respectively while 2 mM of amytal caused 41 and 23% inhibition, respectively. There was no change in the ADP/O ratios. RO-28-2653 (50 muM) did not significantly alter the activity of the respiratory chain complexes or succinate dehydrogenase, although citrate synthase (CS) was inhibited by upto 71 %. This inhibition was non-competitive at a K-i of 25 +/- 5 muM. Inhibitory effects in the presence of hydrophobic substances, such as BSA and Triton X-100, were significantly lower in both test systems, In conclusion, high concentrations of RO-28-2653 impair mitochondrial function, although compared to amytal and 2,4-DNP, this is rather low. The resultant impairment is less pronounced in the more complex skinned muscle fiber system, and is dependent on hydrophobic interactions. (C) 2002 Elsevier Science Inc. All rights reserved.