title: A unifying mechanism for cancer cell death through ion channel activation by HAMLET.
abstract: Ion channels and ion fluxes control many aspects of tissue homeostasis. During oncogenic transformation, critical ion channel functions may be perturbed but conserved tumor specific ion fluxes remain to be defined. Here we used the tumoricidal protein-lipid complex HAMLET as a probe to identify ion fluxes involved in tumor cell death. We show that HAMLET activates a non-selective cation current, which reached a magnitude of 2.74±0.88 nA within 1.43±0.13 min from HAMLET application. Rapid ion fluxes were essential for HAMLET-induced carcinoma cell death as inhibitors (amiloride, BaCl2), preventing the changes in free cellular Na(+) and K(+) concentrations also prevented essential steps accompanying carcinoma cell death, including changes in morphology, uptake, global transcription, and MAP kinase activation. Through global transcriptional analysis and phosphorylation arrays, a strong ion flux dependent p38 MAPK response was detected and inhibition of p38 signaling delayed HAMLET-induced death. Healthy, differentiated cells were resistant to HAMLET challenge, which was accompanied by innate immunity rather than p38-activation. The results suggest, for the first time, a unifying mechanism for the initiation of HAMLET's broad and rapid lethal effect on tumor cells. These findings are particularly significant in view of HAMLET's documented therapeutic efficacy in human studies and animal models. The results also suggest that HAMLET offers a two-tiered therapeutic approach, killing cancer cells while stimulating an innate immune response in surrounding healthy tissues.
authors.affiliation: Department of Microbiology, Immunology and Glycobiology, Institute of Laboratory Medicine, Lund University, Lund, Sweden.
authors.forename: Petter
authors.initials: P
authors.lastname: Storm
authors.forename: Thomas Kjaer
authors.initials: TK
authors.lastname: Klausen
authors.forename: Maria
authors.initials: M
authors.lastname: Trulsson
authors.forename: James
authors.initials: J
authors.lastname: Ho C S
authors.forename: Marion
authors.initials: M
authors.lastname: Dosnon
authors.forename: Tomas
authors.initials: T
authors.lastname: Westergren
authors.forename: Yinxia
authors.initials: Y
authors.lastname: Chao
authors.forename: Anna
authors.initials: A
authors.lastname: Rydström
authors.forename: Henry
authors.initials: H
authors.lastname: Yang
authors.forename: Stine Falsig
authors.initials: SF
authors.lastname: Pedersen
authors.forename: Catharina
authors.initials: C
authors.lastname: Svanborg
mesh_terms: D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000502:physiology*; D045744:Cell Line, Tumor; D016000:Cluster Analysis; D020869:Gene Expression Profiling; D006801:Humans; D007113:Immunity, Innate; D042541:Intracellular Space / Q000378:metabolism; D007473:Ion Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007768:Lactalbumin / Q000276:immunology / Q000378:metabolism*; D009829:Oleic Acids / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism; D015398:Signal Transduction; D012964:Sodium / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C506422:HAMLET complex, human; D007473:Ion Channels; D009829:Oleic Acids; D007768:Lactalbumin; D012964:Sodium; D048051:p38 Mitogen-Activated Protein Kinases; D011188:Potassium; D002118:Calcium