RESUMEN
Mitochondrial Complex I plays a crucial role in the proliferation, chemoresistance, and metastasis of breast cancer (BC) cells. This highlights it as an attractive target for anti-cancer drugs. Using submitochondrial particles, we identified FRV-1, an ortho-carbonyl quinone, which inhibits NADH:duroquinone activity in D-active conformation and reduces the 3ADP state respiration dependent on Complex I, causing mitochondrial depolarization, ATP drop, increased superoxide levels, and metabolic remodeling towards glycolysis in BC cells. Introducing methyl groups at FRV-1 structure produced analogs that acted as electron acceptors at the Complex I level or increased the inhibitory effect of FCCP-stimulated oxygen consumption rate, which correlated with their redox potential, but increased toxicity on RMF-621 human breast fibroblasts was observed. FRV-1 was inactive in the naphthoquinone oxidoreductase 1 (NOQ1)-positive BC cell line, MCF7, but the sensitivity was recovered by dicoumarol, a NOQ1 inhibitor, suggesting that FRV-1 is a NOQ1 substrate. Importantly, FRV-1 selectively inhibited the proliferation, migration, and invasion of NQO1 negative BC cell, MDA-MB-231, in an OXPHOS- and ROS-dependent manner and sensitized it to the BH3 mimetic drug venetoclax. Overall, FRV-1 is a novel Complex I inhibitor in D-active conformation, blocking possibly the re-activation to A-state, producing selective anti-cancer effects in NQO1-negative BC cell lines.
RESUMEN
From the venom of the Bothrops pictus snake, an endemic species from Peru, we recently have described toxins that inhibited platelet aggregation and cancer cell migration. In this work, we characterize a novel P-III class snake venom metalloproteinase, called pictolysin-III (Pic-III). It is a 62 kDa proteinase that hydrolyzes dimethyl casein, azocasein, gelatin, fibrinogen, and fibrin. The cations Mg2+ and Ca2+ enhanced its enzymatic activity, whereas Zn2+ inhibited it. In addition, EDTA and marimastat were also effective inhibitors. The amino acid sequence deduced from cDNA shows a multidomain structure that includes a proprotein, metalloproteinase, disintegrin-like, and cysteine-rich domains. Additionally, Pic-III reduces the convulxin- and thrombin-stimulated platelet aggregation and in vivo, it has hemorrhagic activity (DHM = 0.3 µg). In epithelial cell lines (MDA-MB-231 and Caco-2) and RMF-621 fibroblast, it triggers morphological changes that are accompanied by a decrease in mitochondrial respiration, glycolysis, and ATP levels, and an increase in NAD(P)H, mitochondrial ROS, and cytokine secretion. Moreover, Pic-III sensitizes to the cytotoxic BH3 mimetic drug ABT-199 (Venetoclax) in MDA-MB-231 cells. To our knowledge, Pic-III is the first SVMP reported with action on mitochondrial bioenergetics and may offer novel opportunities for promising lead compounds that inhibit platelet aggregation or ECM-cancer-cell interactions.
RESUMEN
The influence of an inflammatory microenvironment on tumorigenesis has been widely accepted. Systemic conditions that favor the onset of an inflammatory landscape predispose the progression of breast cancer. Under obesity conditions, the endocrine function of adipose tissue is one of the main determinants of the production of local and systemic inflammatory mediators. Although these mediators can stimulate tumorigenesis and recruit inflammatory cells, as macrophages, the mechanism involved remains poorly understood. In the present work, we describe that the TNFα treatment of mammary preadipocytes from human normal patients blocks adipose differentiation and promotes the generation of pro-inflammatory soluble factors. The latter stimulate the mobilization of THP-1 monocytes and MCF-7 epithelial cancer cells in an MCP1/CCL2- and mitochondrial-ROS-dependent manner. Together, these results reaffirm the contribution of an inflammatory microenvironment and mtROS in the progression of breast cancer.
