This study describes the investigation of the efficiency of
conjugated linoleic acid (CLA) isomers in reducing
cancer cells viability exploring the role of the oxidative stress and
acylpeptide hydrolase (APEH)/
proteasome mediated pathways on pro-apoptotic activity of the isomer trans10,cis12 (t10,c12)-CLA. The basal activity/expression levels of APEH and
proteasome (β-5 subunit) were preliminarily measured in eight
cancer cell lines and the functional relationship between these
enzymes was clearly demonstrated through their strong positive correlation. t10,c12-CLA efficiently inhibited the activity of APEH and
proteasome isoforms in cell-free assays and the negative correlation between cell viability and
caspase 3 activity confirmed the pro-apoptotic role of this isomer. Finally, modulatory effects of t10,c12-CLA on cellular redox status (intracellular
glutathione,
mRNA levels of
antioxidant/detoxifying
enzymes activated through
NF-E2-related factor 2, Nrf2, pathway) and on APEH/β-5 activity/expression levels, were investigated in A375
melanoma cells. Dose- and time-dependent variations of the considered parameters were established and the resulting pro-apoptotic effects were shown to be associated with an alteration of the redox status and a down-regulation of APEH/
proteasome pathway. Therefore, our results support the idea that these events are involved in ROS-dependent apoptosis of t10,c12-CLA-treated A375 cells. The combined inhibition, triggered by t10,c12-CLA, via the modulation of APEH/
proteasome and Nrf2 pathway for treating
melanoma, is suggested as a subject for further in vivo studies.