HAMLET kills tumor cells by an apoptosis-like mechanism—cellular, molecular, and therapeutic aspects

https://doi.org/10.1016/S0065-230X(03)88302-1Get rights and content

HAMLET (human α-lactalbumin made lethal to tumor cells) is a protein-lipid complex that induces apoptosis-like death in tumor cells, but leaves fully differentiated cells unaffected. This review summarizes the information on the in vivo effects of HAMLET in patients and tumor models, on the tumor cell biology, and on the molecular characteristics of the complex. HAMLET limits the progression of human glioblastomas in a xenograft model and removes skin papillomas in patients. This broad anti-tumor activity includes >40 different lymphomas and carcinomas and apoptosis is independent of p53 or bcl-2. In tumor cells, HAMLET enters the cytoplasm, translocates to the perinuclear area, and enters the nuclei, where it accumulates. HAMLET binds strongly to histones and disrupts the chromatin organization. In the cytoplasm, HAMLET targets ribosomes and activates caspases. The formation of HAMLET relies on the propensity of α-lactalbumin to alter its conformation when the strongly bound Ca2+ ion is released and the protein adopts the apo-conformation that exposes a new fatty acid binding site. Oleic acid (C18:1,9 cis) fits this site with high specificity, and stabilizes the altered protein conformation. The results illustrate how protein folding variants may be beneficial, and how their formation in peripheral tissues may depend on the folding change and the availability of the lipid cofactor. One example is the acid pH in the stomach of the breast-fed child that promotes the formation of HAMLET This mechanism may contribute to the protective effect of breastfeeding against childhood tumors. We propose that HAMLET should be explored as a novel approach to tumor therapy.

References (96)

  • JensenR.G.

    The lipids in human milk

    Prog. Lipid Res.

    (1996)
  • JohnstoneR.W. et al.

    Apoptosis: A link between cancer genetics and chemotherapy

    Cell

    (2002)
  • KohlerC. et al.

    Protease activation in apoptosis induced by MAL

    Exp. Cell Res.

    (1999)
  • KoradiR. et al.

    MOLMOL: A program for display and analysis of macromolecular structures

    J. Mod. Graph.

    (1996)
    KoradiR. et al.

    MOLMOL: A program for display and analysis of macromolecular structures

    J. Mod. Graph.

    (1996)
  • KuwajimaK.

    The molten globule state as a clue for understanding the folding and cooperativity of globular-protein structure

    Proteins

    (1989)
  • LugerK. et al.

    Crystal structure of the nucleosome core particle at 2.8 A resolution

    Nature

    (1997)
  • MusciG. et al.

    Physiological roles of zinc and calcium binding to alphalactalbumin in lactose biosynthesis

    Biochemistry

    (1985)
  • PaciE. et al.

    Exploration of partially unfolded states of human alpha-lactalbumin by molecular dynamics simulation

    J. Mol. Biol.

    (2001)
  • PengZ.Y. et al.

    Does the molten globule have a native-like tertiary fold?

    Philos. Trans. R. Soc. Lond. B Biol. Sci.

    (1995)
  • PikeA.C. et al.

    Crystal structures of guinea-pig, goat and bovine alpha-lactalbumin highlight the enhanced conformational flexibility of regions that aresignificant for its action in lactose synthase

    Structure

    (1996)
  • RaoK.R. et al.

    Calcium regulates folding and disulfide-bond formation in alpha-lactalbumin

    Biochem. Biophys. Res. Commun.

    (1989)
  • RusselD.S. et al.

    Pathology of Tumors of the Nervous System

    (1989)
  • SaitoM.

    Molecular dynamics model structures for the molten globule state of α-lactalbumin: Aromatic clusters I and II

    Protein Eng.

    (1999)
  • SmithL.J. et al.

    Molecular dynamics simulations of human alpha-lactalbumin: Changes to the structural and dynamical properties of the protein at low pH

    Proteins

    (1999)
  • SvenssonM. et al.

    Molecular characterization of alpha-lactalbumin folding variants that induce apoptosis in tumor cells

    J. Biol. Chem.

    (1999)
  • TellingG.C. et al.

    Prion propagation in mice expressing human and chimeric PrP transgenis implicates the interaction of cellular PrP with another protein

    Cell

    (1995)
  • Wijesinha-BettoniR. et al.

    Comparison of the structural and dynamical properties of holo and apo bovine alpha-lactalbumin by NMR spectroscopy

    J. Mol. Biol.

    (2001)
  • WilsonG. et al.

    The native like tertiary fold in molten globule alpha lactalbumin appears to be controlled by a continuous phase transition

    J. Mol. Biol.

    (1996)
  • WuL.C. et al.

    A specific hydrophobic core in the alpha-lactalbumin molten globule

    J. Mol. Biol.

    (1998)
  • WuL.C. et al.

    Bipartite structure of the alpha-lactalbumin molten globule

    Nat. Struct. Biol.

    (1995)
  • YangJ. et al.

    Prevention of apoptosis by Bcl-2: Release of cytochrome c from mitochondria blocked

    Science

    (1997)
  • AcharyaK.R. et al.

    Crystal structure of human alpha-lactalbumin at 1.7 A resolution

    J. Mol. Biol.

    (1991)
  • AlexandrescuA.T. et al.

    Structure and dynamics of the acid-denatured molten globule state of α-lactalbumin: A two-dimentional NMR study

    Biochemistry

    (1993)
  • AmmannR. et al.

    Topical photodynamic therapy in verrucae. A pilot study

    Dermatology

    (1995)
  • ArentsG. et al.

    Topography of the histone octamer surface: Repeating structural motifs utilized in the docking of nucleosomal DNA

  • BernbackS. et al.

    The complete digestion of human milk triacylglycerol in vitro requires gastric lipase, pancreatic colipase-dependent lipase, and bilesalt-stimulated lipase

    J. Clin. Invest.

    (1990)
  • Bettoni-WijesinhaR. et al.

    Comparson of the structural and dynamical properties of holo and apo bovine α-lactalbumin by NMR spectroscopy

    J. Mol. Biol.

    (2001)
  • BilleterM. et al.

    Prion protein NMR structure and species barrier for prion diseases

  • BlackbergL. et al.

    Recombinant human-milk bile-salt-stimulated lipase. Functional properties are retained in the absence of glycosylation and the unique proline-rich repeats

    Eur. J. Biochem.

    (1995)
  • Bossy-WetzelE. et al.

    Mitochondrial cytochrome c release in apoptosis occurs upstream of DEVD-specific caspase activation and independently of mitochondrial transmembrane depolarization

    EMBO J.

    (1998)
  • BrewK. et al.

    The role of alpha-lactalbumin and the A protein in lactose synthetase: A unique mechanism for the control of a biological reaction

  • BucciantiniM. et al.

    Inherent toxicity of aggregates implies a common mechanism for protein misfolding diseases

    Nature

    (2002)
  • BunneyM.H. et al.

    The treatment of resistant warts with intralesional bleomycin: A controlled clinical trial

    Br. J. Dermatol.

    (1984)
  • BykovV.J. et al.

    Restoration of the tumor suppressor function to mutant p53 by a low-molecular-weight compound

    Nat. Med.

    (2002)
  • CistolaD.P.

    Fat sites found

    Nat. Struct. Biol.

    (1998)
  • CurryS. et al.

    Crystal structure of human serum albumin complexed with fatty acid reveals an asymmetric distribution of binding sites

    Nat. Struct. Biol.

    (1998)
  • DautignyA. et al.

    cDNA and amino acid sequences of rainbow trout (Oncorhynchus mykiss) lysozymes and their implications for the evolution of lysozyme and lactalbumin

    J. Mol. Evol.

    (1991)
  • DaviesM.S. et al.

    The gene for human alpha-lactalbumin is assigned to chromosome 12q13

    Ann. Hum. Genet.

    (1987)
  • Cited by (154)

    • Biopharmaceutical nanoclusters: Towards the self-delivery of protein and peptide therapeutics

      2022, Journal of Controlled Release
      Citation Excerpt :

      α-lactalbumin (α-LAC) is an example of a protein with potential therapeutic effect in the treatment of GI-tract-related conditions, different neurological conditions as well as cancer, of which BNCs have been prepared [32–34,69]. Conjugation of α-LAC to oleic acid to form the complex named Human α-LAC Made Lethal to Tumor cells (HAMLET) potentiates its anti-cancer effect [70–72]. Using deionized water as solvent, ethanol as antisolvent and GTA as crosslinking agent post-desolvation, BNCs with a size of approximately 150 nm have been prepared.

    • Drug-loaded oleic-acid grafted mesoporous silica nanoparticles conjugated with α-lactalbumin resembling BAMLET-like anticancer agent with improved biocompatibility and therapeutic efficacy

      2022, Materials Today Bio
      Citation Excerpt :

      HAMLET or BAMLET (human/bovine α-lactalbumin made lethal against tumor cells), the widely known anticancer agent, are formed as the lipoprotein complex [25]. Since HAMLET was firstly identified from human milk in 1995, these anticancer agents have been extensively studied due to their noticeable ability to kill diverse cancers cells and negligible cytotoxicity to normal cells [26,27]. Notably, as α-lactalbumin is a major protein of natural dietary nutrient, HAMLET/BAMLET is regarded as extremely safe anticancer agent [28–31].

    • The Contribution of Bioactive Peptides of Whey to Quality of Food Products

      2018, Food Processing for Increased Quality and Consumption
    View all citing articles on Scopus
    View full text