Inhibition of mitochondrial respiration mediates apoptosis induced by the anti-tumoral alkaloid lamellarin D

Abstract

Lamellarin D (Lam D), a marine alkaloid, exhibits a potent cytotoxicity against many different tumors. The pro-apoptotic function of Lam D has been attributed to its direct induction of mitochondrial permeability transition (MPT). This study was undertaken to explore the mechanisms through which Lam D promotes changes in mitochondrial function and as a result apoptosis. The use of eight Lam derivatives provides useful structure-apoptosis relationships. We demonstrate that Lam D and structural analogues induce apoptosis of cancer cells by acting directly on mitochondria inducing reduction of mitochondrial membrane potential, swelling and cytochrome c release. Cyclosporin A, a well-known inhibitor of MPT, completely prevents mitochondrial signs of apoptosis. The drug decreases calcium uptake by mitochondria but not by microsomes indicating that Lam D-dependent permeability is specific to mitochondrial membranes. In addition, upon Lam D exposure, a rapid decline of mitochondrial respiration and ATP synthesis occurs in isolated mitochondria as well as in intact cells. Evaluation of the site of action of Lam D on the electron-transport chain revealed that the activity of respiratory chain complex III is reduced by a half. To determine whether Lam D could induce MPT-dependent apoptosis by inhibiting mitochondrial respiration, we generated respiration-deficient cells (rho0) derived from human melanoma cells. In comparison to parental cells, rho0 cells are totally resistant to the induction of MPT-dependent apoptosis by Lam D. Our results indicate that functional mitochondria are required for Lam D-induced apoptosis. Inhibition of mitochondrial respiration is responsible for MPT-dependent apoptosis of cancer cells induced by Lam-D.

Inactivation of the HIF-1α/PDK3 Signaling Axis Drives Melanoma toward Mitochondrial Oxidative Metabolism and Potentiates the Therapeutic Activity of Pro-Oxidants

“…1B and (28, 29)]. All melanoma cell lines studied had a cell death profile similar to that of mitochondrial DNA-depleted melanoma cells (HBL r 0 ), which lack functional ETC (24). Inhibition of ATP synthase with oligomycin had almost no impact on ATP in melanoma cells, whereas in HL60, ATP level was highly sensitive to inhibition by oligomycin (Fig.…”

“…23)] DCA, and/or elesclomol were added 48 hours after transfection. HBL cells lacking mitochondrial DNA (HBL r 0 ) were generated as published (24). The A375 cell line, which harbors the BRAFV600E mutation, was treated with vemurafenib to obtain the resistant subline (A375-R) as described in the Supplementary material.…”

Rotational Energy Barrier around the C1–C11 Single Bond in Lamellarins: A Study by Variable-Temperature NMR

“…in 1985. [2][3][4][5][6][7][8][9][10][11][12][13][14][15] These lamellarins exhibit a number of interesting biological activities such as potent cytotoxicity against cancer cell lines, 8,9,11,12,[14][15][16][17][18][19][20][21] multi-drug resistance (MDR) reversal activity, 15,16 anti-HIV activity, 11,18,22 topoisomerase I inhibitory activity, 23,24 inhibition of mitochondrial function, [25][26][27][28] and protein kinases inhibitory activity. 29 Lamellarins possess a unique 14-phenyl-6H- [1]benzopyrano- According to X-ray crystallographic analyses of several lamellarins, the aryl group attached to C1 is This paper is dedicated to Professor Dr. Victor Snieckus on the occasion of his 77 th birthday.…”

Poisoning of Mitochondrial Topoisomerase I by Lamellarin D

“…Its proapoptotic activity has been associated with the generation of DNA breaks resulting from the trapping of nuclear topoisomerase I [Top1-DNA covalent complexes (Top1cc) (Facompre et al, 2003)]. However, Lam-D has also been shown to directly target mitochondria (Kluza et al, 2006;Ballot et al, 2009;Ballot et al, 2010), suggesting that it may poison Top1mt and could act as a potential drug targeting mtDNA by trapping Top1mt. In this study we investigated the effects of Lam-D on Top1mt using in vitro and in vivo DNA cleavage assays in addition to singlemolecule supercoil relaxation measurements.…”