Human SCO1 fulfills essential roles in cytochrome c oxidase (COX) assembly and the regulation of copper (Cu) homeostasis, yet it remains unclear why pathogenic mutations in this gene cause such clinically heterogeneous forms of disease. Here, we establish a Sco1 mouse model of human disease and show that ablation of Sco1 expression in the liver is lethal owing to severe COX and Cu deficiencies. We further demonstrate that the Cu deficiency is explained by a functional connection between SCO1 and CTR1, the high-affinity transporter that imports Cu into the cell. CTR1 is rapidly degraded in the absence of SCO1 protein, and we show that its levels are restored in Sco1 mouse embryonic fibroblasts upon inhibition of the proteasome. These data suggest that mitochondrial signaling through SCO1 provides a post-translational mechanism to regulate CTR1-dependent Cu import into the cell, and they further underpin the importance of mitochondria in cellular Cu homeostasis.
Matrix metalloproteinase-14 (MMP-14) is a clinically relevant target in metastatic cancers due to its role in tumor progression and metastasis. Since active MMP-14 is localized on the cell surface, it is amenable to antibody-mediated blockade in cancer, and here we describe our efforts to develop novel inhibitory anti-MMP-14 antibodies. A phage-displayed synthetic humanized Fab library was screened against the extracellular domain of MMP-14 and a panel of MMP14-specific Fabs were identified. A lead antibody that inhibits the catalytic domain of MMP-14 (Fab 3369) was identified and treatment of MDA-MB-231 breast cancer cells with Fab 3369 led to significant loss of extracellular matrix degradation and cell invasion abilities. In mammary orthotopic tumor xenograft assays, MMP-14 blockade by IgG 3369 limited tumor growth and metastasis. Analysis of tumor tissue sections revealed that MMP-14 blockade limited tumor neoangiogenesis and hypoxia. Similar effects of MMP-14 blockade in syngeneic 4T1 mammary tumors were observed, along with increased detection of cytotoxic immune cell markers. In conclusion, we show that immunotherapies targeting MMP-14 can limit immune suppression, tumor progression, and metastasis in triple-negative breast cancer.
BackgroundSubstantially elevated blood D-lactate (DLA) concentrations are associated with neurocardiac toxicity in humans and animals. The neurological symptoms are similar to inherited or acquired abnormalities of pyruvate metabolism. We hypothesized that DLA interferes with mitochondrial utilization of L-lactate and pyruvate in brain and heart.MethodsRespiration rates in rat brain, heart and liver mitochondria were measured using DLA, LLA and pyruvate independently and in combination.ResultsIn brain mitochondria, state 3 respiration was 53% and 75% lower with DLA as substrate when compared with LLA and pyruvate, respectively (p < 0.05). Similarly in heart mitochondria, state 3 respiration was 39% and 86% lower with DLA as substrate when compared with LLA or pyruvate, respectively (p < 0.05). However, state 3 respiration rates were similar between DLA, LLA and pyruvate in liver mitochondria. Combined incubation of DLA with LLA or pyruvate markedly impaired state 3 respiration rates in brain and heart mitochondria (p < 0.05) but not in liver mitochondria. DLA dehydrogenase activities were 61% and 51% lower in brain and heart mitochondria compared to liver, respectively, whereas LLA dehydrogenase activities were similar across all three tissues. An LDH inhibitor blocked state 3 respiration with LLA as substrate in all three tissues. A monocarboxylate transporter inhibitor blocked respiration with all three substrates.ConclusionsDLA was a poor respiratory substrate in brain and heart mitochondria and inhibited LLA and pyruvate usage in these tissues. Further studies are warranted to evaluate whether these findings support, in part, the possible neurological and cardiac toxicity caused by high DLA levels.
Flaxseed as well as its oil component possess antitumor activities against different types of cancer and have been used by some patients as complementary and/or alternative medicine. Linoorbitides (LOBs) are one family of flaxseed compounds that has implications for anticancer and antioxidant activity. The cytotoxicity of [1-9-NαC]-linusorb-B3 (LOB3), [1-9-NαC]-linusorb-B2 (LOB2), [1-9-NαC],[1-Rs,Ss-MetO]-linusorb-B2 ([MetO]-LOB2) and [1-8-NαC],[1-Rs,Ss-MetO]-linusorb-B1 ([MetO]-LOB1) was measured against human breast cancer Sk-Br-3 and MCF7 cell lines and melanoma A375 cell line. Overall cytotoxicity is cell-type specific. It scales as the hydrophobicity and concentration of the LOBs with the most abundant LOB3 being the most cytotoxic. Oral administration of LOB3 as a potential therapeutic agent might not be applicable as a much too high and/or frequent dose would be required to achieve a serum concentration of 400–500 μg/mL due to bioavailability and pharmacokinetic factors. However, LOB3 may be suitable for topical treatment formulations or as a lead compound in developing anticancer LOB derivatives.
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