title: The cytotoxicity of BAMLET complexes is due to oleic acid and independent of the α-lactalbumin component.
abstract: Lipid-protein complexes comprised of oleic acid (OA) non-covalently coupled to human/bovine α-lactalbumin, named HAMLET/BAMLET, display cytotoxic properties against cancer cells. However, there is still a substantial debate about the role of the protein in these complexes. To shed light into this, we obtained three different BAMLET complexes using varying synthesis conditions. Our data suggest that to form active BAMLET particles, OA has to reach critical micelle concentration with an approximate diameter of 250 nm. Proteolysis experiments on BAMLET show that OA protects the protein and is probably located on the surface, consistent with a micelle-like structure. Native or unfolded α-lactalbumin without OA lacked any tumoricidal activity. In contrast, OA alone killed cancer cells with the same efficiency at equimolar concentrations as its formulation as BAMLET. Our data show unequivocally that the cytotoxicity of the BAMLET complex is exclusively due to OA and that OA alone, when formulated as a micelle, is as toxic as the BAMLET complex. The contradictory literature results on the cytotoxicity of BAMLET might be explained by our finding that it was imperative to sonicate the samples to obtain toxic OA.
authors.affiliation: Department of Biology, University of Puerto Rico, Río Piedras Campus, P.O. Box 23360, San Juan 00931-3346, Puerto Rico.
authors.forename: Yamixa
authors.initials: Y
authors.lastname: Delgado
authors.affiliation: Department of Biology, University of Puerto Rico, Río Piedras Campus, P.O. Box 23360, San Juan 00931-3346, Puerto Rico.
authors.forename: Moraima
authors.initials: M
authors.lastname: Morales-Cruz
authors.affiliation: Department of Chemistry, University of Puerto Rico, Río Piedras Campus, P.O. Box 23360, San Juan 00931-3346, Puerto Rico.
authors.forename: Cindy M
authors.initials: CM
authors.lastname: Figueroa
authors.affiliation: Department of Biology, University of Puerto Rico, Río Piedras Campus, P.O. Box 23360, San Juan 00931-3346, Puerto Rico.
authors.forename: José
authors.initials: J
authors.lastname: Hernández-Román
authors.affiliation: Department of Biology, University of Puerto Rico, Río Piedras Campus, P.O. Box 23360, San Juan 00931-3346, Puerto Rico.
authors.forename: Glinda
authors.initials: G
authors.lastname: Hernández
authors.affiliation: Department of Biology, University of Puerto Rico, Río Piedras Campus, P.O. Box 23360, San Juan 00931-3346, Puerto Rico ; Department of Chemistry, University of Puerto Rico, Río Piedras Campus, P.O. Box 23360, San Juan 00931-3346, Puerto Rico.
authors.forename: Kai
authors.initials: K
authors.lastname: Griebenow
keywords: BAMLET; BAMLET, bovine α-lactalbumin made lethal to tumor cells; Cancer therapy; DLS, dynamic light scattering; EPR, enhanced permeability and retention; FA, fatty acid; Fatty acid; FoA, folic acid; HAMLET; HAMLET, human α-lactalbumin made lethal to tumor cells; MTS, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium; NP, nanoparticles; OA, oleic acid; Oleic acid; PMS, phenazine methosulfate; SEM, scanning electron microscopy; α-LA, α-lactalbumin; α-Lactalbumin