α-Lactalbumin-oleic acid complex kills tumor cells by inducing excess energy metabolism but inhibiting mRNA expression of the related enzymes

Abstract

Previous studies have demonstrated that the anti-tumor α-lactalbumin-oleic acid complex (α-LA-OA) may target the glycolysis of tumor cells. However, few data are available regarding the effects of α-LA-OA on energy metabolism. In this study, we measured glycolysis and mitochondrial functions in HeLa cells in response to α-LA-OA using the XF flux analyzer (Seahorse Bioscience, North Billerica, MA). The gene expression of enzymes involved in glycolysis, tricarboxylic acid cycle, electron transfer chain, and ATP synthesis were also evaluated. Our results show that α-LA-OA significantly enhanced the basal glycolysis and glycolytic capacity. Mitochondrial oxidative phosphorylation, including the basal respiration, maximal respiration, spare respiratory capacity and ATP production were also improved in response to α-LA-OA. The enhanced mitochondrial functions maybe partly due to the increased capacity of utilizing fatty acids and glutamine as the substrate. However, the gene expressions of pyruvate kinase M2, lactate dehydrogenase A, aconitate hydratase, and isocitrate dehydrogenase 1 were inhibited, suggesting an insufficient ability for the glycolysis process and the tricarboxylic acid cycle. The increased expression of acetyl-coenzyme A acyltransferase 2, a central enzyme involved in the β-oxidation of fatty acids, would enhance the unbalance due to the decreased expression of electron transfer flavoprotein β subunit, which acts as the electron acceptor. These results indicated that α-LA-OA may induce oxidative stress due to conditions in which the ATP production is exceeding the energy demand. Our results may help clarify the mechanism of apoptosis induced by reactive oxygen species and mitochondrial destruction.

Comprehensive proteomics and functional annotation of mouse brown adipose tissue

“…The other proteins included enzymes in the mitochondria that are mainly related to catabolism. Specifically, aconitate hydratase, long-chain specific acyl-CoA dehydrogenase, 3-ketoacyl-CoA thiolase and alpha-enolase were identified as enzymes related to fatty acid oxidation [42,43], tricarboxylic acid cycle [44] and glycolysis [45]. Electron transfer flavoprotein subunit alpha and cytochrome c oxidase subunit 5A have also been related to mitochondrial respiration [46].…”

α-Lactalbumin, Amazing Calcium-Binding Protein

“…The authors concluded that α-LA-oleic acid exerted its antitumor activity by disrupting cytoskeleton stability and cell motility, and by inhibiting DNA, lipid, and adenosine triphosphate synthesis, leading to cellular stress and activation of programmed cell death. The same authors [ 289 ] found that α-LA-oleic acid treatment of HeLa cells may induce a condition in which the ATP production exceeds the energy demand, which would lead to oxidative stress and activation of apoptosis.…”

Improved antitumor activity and IgE/IgG–binding ability of α‐Lactalbumin/β‐lactoglobulin induced by ultrasonication prior to binding with oleic acid

“…Among, whey protein molecules have been shown to interact with different bioactive compounds, including retinol and fatty acids (Barbiroli et al., 2010; Collini et al., 2003), with the resulting complex exhibiting a variety of functional characteristics. For example, BAMLET (Bovine α‐La Made Lethal to Tumor cells) is a tumoricidal complex consisting of α‐La and oleic acid (OA) (Fang et al., 2018; Rammer et al., 2010). Another protein, β‐Lg, can also bind to OA to give a complex β‐Lg‐OA, which exhibited similar antitumor activity (Fang et al., 2015), and also resulted in the decline of IgG‐binding ability (Zhong et al., 2019).…”