The oncolytic peptide LTX-315 kills cancer cells through Bax/Bak-regulated mitochondrial membrane permeabilization

// Heng Zhou 1,2,3,4,5 , Sabrina Forveille 1,2,3,4 , Allan Sauvat 1,2,3,4 , Valentina Sica 1,2,3,4,5 , Valentina Izzo 1,2,3,4 , Sylvère Durand 1,2,3,4 , Kevin Müller 1,2,3,4,5 , Peng Liu 1,2,3,4,5 , Laurence Zitvogel 5,6,7 , Øystein Rekdal 9,10 , Oliver Kepp 1,2,3,4 and Guido Kroemer 1,2,3,4,11,12 1 Metabolomics and Cell Biology Platforms, Gustave Roussy Comprehensive Cancer Institute, Villejuif, France 2 Equipe 11 Labellisée Ligue Contre le Cancer, Centre de Recherche des Cordeliers, INSERM U 1138, Paris, France 3 Université Paris Descartes, Sorbonne Paris Cité, Paris, France 4 Université Pierre et Marie Curie, Paris, France 5 University of Paris Sud XI, Kremlin Bicêtre, France 6 Department of Immuno-Oncology, Institut de Cancérologie Gustave Roussy Cancer Campus, Villejuif, France 7 Institut National de la Santé et de la Recherche Medicale (INSERM), U1015, Villejuif, France 8 Center of Clinical Investigations in Biotherapies of Cancer (CICBT) 507, Villejuif, France 9 Lytix Biopharma, Oslo, Norway 10 University of Tromsø, Institute of Medical Biology, Tromsø, Norway 11 Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France 12 Karolinska Institute, Department of Women’s and Children’s Health, Karolinska University Hospital, Stockholm, Sweden Correspondence to: Oliver Kepp , email: // Guido Kroemer, email: // Keywords : LTX-315, necrosis, mitochondrial membrane permeabilization, cancer, mitophagy Received : July 31, 2015 Accepted : August 26, 2015 Published : September 10, 2015 Abstract LTX-315 has been developed as an amphipathic cationic peptide that kills cancer cells. Here, we investigated the putative involvement of mitochondria in the cytotoxic action of LTX-315. Subcellular fractionation of LTX-315-treated cells, followed by mass spectrometric quantification, revealed that the agent was enriched in mitochondria. LTX-315 caused an immediate arrest of mitochondrial respiration without any major uncoupling effect. Accordingly, LTX-315 disrupted the mitochondrial network, dissipated the mitochondrial inner transmembrane potential, and caused the release of mitochondrial intermembrane proteins into the cytosol. LTX-315 was relatively inefficient in stimulating mitophagy. Cells lacking the two pro-apoptotic multidomain proteins from the BCL-2 family, BAX and BAK, were less susceptible to LTX-315-mediated killing. Moreover, cells engineered to lose their mitochondria (by transfection with Parkin combined with treatment with a protonophore causing mitophagy) were relatively resistant against LTX-315, underscoring the importance of this organelle for LTX-315-mediated cytotoxicity. Altogether, these results support the notion that LTX-315 kills cancer cells by virtue of its capacity to permeabilize mitochondrial membranes.