Molecular Mechanisms of the Cytotoxicity of Human α-Lactalbumin Made Lethal to Tumor Cells (HAMLET) and Other Protein-Oleic Acid Complexes

Nakamura, Takashi; Aizawa, Tomoyasu; Kariya, Ryusho; Okada, Seiji; Demura, Makoto; Kawano, Keiichi; Makabe, Koki; Kuwajima, Kunihiro

doi:10.1074/jbc.m112.437889

Cited by 49 publications

(40 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The protein-OA complexes are prepared from bovine -lactalbumin (BLA, BAMLET) 1 , equine lysozyme (EL, ELOA) 2 , goat -lactalbumin (GLA, GAMLET) 9 and other proteins that are made to bind OA using a variety of approaches, including passage of the protein through a column equilibrated with OA 2; 4 , direct titration of OA into a protein solution 3; 10 , and heat treatment 9; 11 . HAMLET was initially thought to consist of one, or only a few, oleic acids initially described as "cofactors" 12 .…”

Section: Accepted Manuscriptmentioning

confidence: 99%

α-Lactalbumin:Oleic Acid Complex Spontaneously Delivers Oleic Acid to Artificial and Erythrocyte Membranes

Wen

Strømland

Halskau

2015

Journal of Molecular Biology

View full text Add to dashboard Cite

Human α-lactalbumin made lethal to tumor cells (HAMLET) is a tumoricidal complex consisting of human α-lactalbumin and multiple oleic acids (OAs). OA has been shown to play a key role in the activity of HAMLET and its related complexes, generally known as protein-fatty acid (PFA) complexes. In contrast to what is known about the fate of the protein component of such complexes, information about what happens to OA during their action is still lacking. We monitored the membrane, OA and protein components of bovine α-lactalbumin complexed with OA (BLAOA; a HAMLET-like substance) and how they associate with each other. Using ultracentrifugation, we found that the OA and lipid components follow each other closely. We then firmly identify a transfer of OA from BLAOA to both artificial and erythrocyte membranes, indicating that natural cells respond similarly to BLAOA treatment as artificial membranes. Uncomplexed OA is unable to similarly affect membranes at the conditions tested, even at elevated concentrations. Thus, BLAOA can spontaneously transfer OA to a lipid membrane. After the interaction with the membrane, the protein is likely to have lost most or all of its OA. We suggest a mechanism for passive import of mainly uncomplexed protein into cells, using existing models for OA's effect on membranes. Our results are consistent with a membrane destabilization mediated predominantly by OA insertion being a significant contribution to PFA cytotoxicity.

show abstract

Section: Accepted Manuscriptmentioning

confidence: 99%

α-Lactalbumin:Oleic Acid Complex Spontaneously Delivers Oleic Acid to Artificial and Erythrocyte Membranes

Wen

Strømland

Halskau

2015

Journal of Molecular Biology

View full text Add to dashboard Cite

show abstract

“…The mechanism of the antitumor activity of HAMLET (human α-lactalbumin made lethal to tumor cells)-like complexes has been studied extensively (Hallgren et al, 2006;Aits et al, 2009;Zhang et al, 2013), and the toxicity of these complexes has been reported to be highly dependent on OA (Brinkmann et al, 2011;Nakamura et al, 2013). Furthermore, the antitumor properties of OA have been widely acknowledged (Brinkmann et al, 2011;Carrillo et al, 2012;Hoque et al, 2013;Fang et al, 2014).…”

Section: Introductionmentioning

confidence: 95%

Self-assembled β-lactoglobulin–oleic acid and β-lactoglobulin–linoleic acid complexes with antitumor activities

Fang

Zhang

Tian

et al. 2015

Journal of Dairy Science

View full text Add to dashboard Cite

β-Lactoglobulin (β-LG) can bind to fatty acids such as oleic acid (OA) and linoleic acid (LA). Another whey protein, α-lactalbumin (α-LA), can also bind to OA to give the complex α-LA-OA, which has antitumor properties. Based on reports that the activity of α-LA-OA is highly dependent on OA, as well as the acquisition of similar complexes using other proteins, such as lysozyme and lactoferrin, we speculated whether β-LG could also kill tumor cells after binding to other fatty acids. Therefore, we prepared complexes of β-LG with OA (β-LG-OA) and LA (β-LG-LA) in the current study and evaluated them in terms of antitumor activity and thermostability using the methylene blue method and differential scanning calorimetry, respectively. The structural features of these complexes were also evaluated using fluorescence spectroscopy and circular dichroism. The binding dynamics of OA and LA to β-LG were studied using isothermal titration calorimetry. Cell viability results revealed that β-LG-LA and β-LG-OA exhibited similar antitumor activities. Interestingly, the binding of β-LG to LA led to an increase in its thermostability, whereas its binding to OA had very little effect. The environments of the tryptophan residues in the β-LG-OA and β-LG-LA complexes were very different, with the residues being blue- and red-shifted, respectively. Furthermore, the hydrophobic regions in β-LG were buried after binding of OA, which was slightly changed in β-LG-LA. Circular dichroism results showed that β-LG-OA enhanced the tertiary structure, which was partially lost in β-LG-LA. There were more binding sites for OA than for LA on β-LG, although the binding constants of the 2 fatty acids were similar, with both acids interacting with the protein though van der Waals and hydrogen bonding interactions. This study could help provide a deeper understanding of the structural basis for formation of antitumor protein-fatty acid complexes.

show abstract

“…In addition, intact milk proteins have been associated with a wide range of in vitrobioactivities, such as satiating, antimicrobial, mineral binding, anti-lipidaemic and anticancer properties [2,28,30,93]. During digestion in humans, milk proteins are cleaved by various proteinases and peptidases in the gastrointestinal tract (GIT), resulting in the generation of free amino acids and peptides [131].…”

Section: Introductionmentioning

confidence: 99%

Bioactive properties of milk proteins in humans: A review

Nongonierma

Fitzgerald

2015

Peptides

View full text Add to dashboard Cite

Many studies have demonstrated that milk protein consumption has benefits in terms of promoting human health. This review assesses the intervention studies which have evaluated potential health enhancing effects in humans following the ingestion of milk proteins. The impact of milk protein ingestion has been studied to asses their satiating, hypotensive, antimicrobial, anti-inflammatory, anticancer, antioxidant, insulinotropic properties as well as their impact on morphological modifications (e.g., muscle and fat mass) in humans. Consistent health promoting effects appear to have been observed in certain instances (i.e., muscle protein synthesis, insulinotropic and hypotensive activity). However, controversial outcomes have also been reported (i.e., antimicrobial, antiinflammatory, anticancer and antioxidant properties). Several factors including interindividual differences, the timing of protein ingestion as well as the potency of the active components may explain these differences. In addition, processing conditions have been reported, in certain instances, to affect milk protein structure and therefore modify their bioactive potential. It is thought that the health promoting properties of milk proteins are linked to the release of bioactive peptides (BAPs) during gastrointestinal digestion. There is a need for further research to develop a more in-depth understanding on the possible mechanisms involved in the observed physiological effects. In addition, more carefully controlled and appropriately powered human intervention studies are required to demonstrate the health enhancing properties of milk proteins in humans.

show abstract

Molecular Mechanisms of the Cytotoxicity of Human α-Lactalbumin Made Lethal to Tumor Cells (HAMLET) and Other Protein-Oleic Acid Complexes

Cited by 49 publications

References 63 publications

α-Lactalbumin:Oleic Acid Complex Spontaneously Delivers Oleic Acid to Artificial and Erythrocyte Membranes

α-Lactalbumin:Oleic Acid Complex Spontaneously Delivers Oleic Acid to Artificial and Erythrocyte Membranes

Self-assembled β-lactoglobulin–oleic acid and β-lactoglobulin–linoleic acid complexes with antitumor activities

Bioactive properties of milk proteins in humans: A review

Contact Info

Product

Resources

About