Cancer cell mitochondria are direct proapoptotic targets for the marine antitumor drug lamellarin D.
Lamellarin D is a marine alkaloid with a pronounced cytotoxicity against a large panel of cancer cell lines and is a potent inhibitor of topoisomerase I. However, lamellarin D maintains a marked cytotoxicity toward cell lines resistant to the reference topoisomerase I poison camptothecin. We therefore hypothesized that topoisomerase I is not the only cellular target for the drug. Using complementary cell-based assays, we provide evidence that lamellarin D acts on cancer cell mitochondria to induce apoptosis. Lamellarin D, unlike camptothecin, induces early disruption of the inner mitochondrial transmembrane potential (Deltapsi(m)) in the P388 leukemia cell line. The functional alterations are largely prevented by cyclosporin A, an inhibitor of the mitochondrial permeability transition (MPT), but not by the inhibitor of caspases, benzyloxycarbonyl-Val-Ala-Asp(Ome)-fluoromethylketone. Deltapsi(m) disruption is associated with mitochondrial swelling and cytochrome c leakage. Using a reliable real-time flow cytometric monitoring of Deltapsi(m) and swelling of mitochondria isolated from leukemia cells, we show that lamellarin D has a direct MPT-inducing effect. Furthermore, mitochondria are required in a cell-free system to mediate lamellarin D-induced nuclear apoptosis. The direct mitochondrial effect of lamellarin D accounts for the sensitivity of topoisomerase I-mutated P388CPT5 cells resistant to camptothecin. Interestingly, a tumor-active analogue of lamellarin D, designated PM031379, also exerts a direct proapoptotic action on mitochondria, with a more pronounced activity toward mitochondria of tumor cell lines compared with nontumor cell lines. Altogether, this work reinforces the pharmacologic interest of the lamellarins and defines lamellarin D as a lead in the search for treatments against chemoresistant cancer cells.
Institut National de la Santé et de la Reserche Médicale U-524, Institut de Recherche sur le Cancer de Lille, France.
Jérôme
J
Kluza
Miguel-Angel
MA
Gallego
Anne
A
Loyens
Jean-Claude
JC
Beauvillain
José-Maria Fernandez
JM
Sousa-Faro
Carmen
C
Cuevas
Philippe
P
Marchetti
Christian
C
Bailly
D000230:Adenocarcinoma / Q000188:drug therapy / Q000473:pathology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001943:Breast Neoplasms / Q000188:drug therapy / Q000473:pathology; D002166:Camptothecin / Q000494:pharmacology; D045744:Cell Line, Tumor; D002463:Cell Membrane Permeability; D002474:Cell-Free System; D003374:Coumarins / Q000494:pharmacology*; D045304:Cytochromes c / Q000378:metabolism; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology*; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology*; D007941:Leukemia P388 / Q000188:drug therapy / Q000473:pathology; D008175:Lung Neoplasms / Q000188:drug therapy / Q000473:pathology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000502:physiology; D041681:NIH 3T3 Cells; D051381:Rats
D000970:Antineoplastic Agents; D003374:Coumarins; D006576:Heterocyclic Compounds, 4 or More Rings; D007546:Isoquinolines; C455554:lamellarin D; D045304:Cytochromes c; D002166:Camptothecin