Destabilization of mitochondrial functions as a target against breast cancer progression: Role of TPP + -linked-polyhydroxybenzoates

Complex Mitochondrial Dysfunction Induced by TPP+-Gentisic Acid and Mitochondrial Translation Inhibition by Doxycycline Evokes Synergistic Lethality in Breast Cancer Cells

“…As shown in Figure 4D,G, consistent with the αKGDHC activity assay, both dm-αKG and mAsp, but not Pyr, partially rescued the cytotoxic effect of GA-TPP + C 10 in the MCF7 and MDA-MB-231 cancer cells, suggesting that inhibition of αKGDHC activity is a relevant step for the promotion of mitochondrial dysfunction. Taken together, our results describe GA-TPP + C 10 as a compound with three phases of interaction with mitochondria in a time-dependent manner: (1) initial phase of mitochondrial uptake with an uncoupling effect, as previously reported [20], (2) inhibition of Complex I-dependent respiration, and (3) late phase of mitochondrial accumulation with inhibition of αKGDHC activity ( Figure 4I).…”

“…Previously, we showed that TPP + C 10 -linked polyphenols instantly produce an increase in mitochondrial respiration in state 4o [19], suggesting a possible uncoupling effect of OXPHOS in cancer cells [20,21]; however, the mechanism and site of action of these compounds in mitochondria remain uncertain. Therefore, we evaluated the effect of GA-TPP + C 10 on oligomycin-insensitive respiration (apparent state 4o) in the MCF7 and MDA-MB-231 BC cells three times after exposure.…”

“…The synthesis of GA-TPP + C 10 was carried out according to Sandoval-Acuna et al [20]. All stock solutions were prepared in dimethyl sulfoxide (DMSO) (Merck, Darmstadt, Germany).…”

“…The cell death induced in MCF7, MDA-MB-231 and MCF-10F cells by GA-TPP + C 10 (2.5 µM), Doxy (10, 25, and 50 µM) and the GA-TPP + C 10 plus Doxy combination was evaluated using annexin V/propidium iodide (AV/PI) dual staining, following the instructions of the Annexin V-FITC Apoptosis Detection Kit (Abcam, Cambridge, UK), as previously reported [20]. For evaluation of the effect of mitochondrial bioenergetic inhibition induced by GA-TPP + C 10 on the viability of BC cells, MCF7 and MDA-MB-231 cells were treated with Pyr (5 mM) and the cell-penetrating metabolic intermediates l-aspartic acid β-methyl ester (mAsp, 5 mM) and dimethyl α-ketoglutarate (dm-KG, 5 mM) for 24 h; then, they were exposed to GA-TPP + C 10 (10 µM) for 48 h, and cell death was determined.…”

“…We showed that TPP + -linked natural hydroxybenzoic acids induce OXPHOS inhibition and consistently decrease mitochondrial depolarization and ATP without increasing ROS production. Interestingly, these derivatives trigger mitochondrial metabolic stress, leading to the selective release of proapoptotic factors in several cancer cell lines, exhibiting antitumoral activities [19,20] with nonobservable toxicity in nontumoral tissues in vivo [21].…”