Studying Anticancer Drug Properties in Drosophila Figure 7. Suppression of white-mottled PEV by Topo II poisons. Photographs show representative eyes of 5-day old wm4h females hatched from late L3 larvae fed etoposide (VP16), F14512 or teniposide (VM26) at the indicated concentrations. A comparison of the no-drug controls shown in the left column highlights the intrinsic heterogeneity of the white-mottled phenotype. Etoposide and F14512 partly suppress white PEV at higher concentrations and display an apparent threshold effect at 25 mM or 50 mM, respectively. Teniposide feeding leads to full dose-dependent suppression of PEV. Controls (wm4h or wild-type Oregon R larvae fed 0 or 1% DMSO used to dilute the drugs, a concentration that corresponds to that used in 100-mM drug treatments) are shown in the bottom row. The graph at the bottom shows the corresponding quantifications of extracted eye pigment and represents mean values obtained from three independent experiments performed in duplicate (30 5-day old females scored for each condition). Results are represented as % pigment relative to Oregon R wild-type (WT) flies fed 1% DMSO. Error bars represent the experimental error. Note that the toxicity of F14512 feeding at 25 and 50 mM only permitted analysis of 10 females for each experiment, most likely accounting for the substantial variations observed (p,0.2 in contrast to p,0.01 for other drug treatments). doi:10.1371/journal.pone.0023597.g007 photographed using a Leica MZ-FLIII binocular microscope equipped with a CoolSnap CCD camera. Results F14512 is a potent inducer of Topo II cleavable complexes on naked DNA F14512 is a novel epipodophyllotoxin-based Topo II inhibitor vectorized towards cancer cells through its spermine moiety (Figure 1). The relationship between its potent cytotoxic effects [24] and its activities as an inducer of Topo II-mediated cleavage, which differ in vitro and in cellulo, remains unclear. F14512 was previously shown to induce DNA cleavage when incubated with purified human Topo II and a cMYC DNA probe, and was shown to be more potent than teniposide [24]. Using the Drosophila melanogaster model system to further characterize the specific features of F14512, we first performed similar experiments using a cloned DNA fragment corresponding to the histone-gene repeat of PLoS ONE | www.plosone.org 8 August 2011 | Volume 6 | Issue 8 | e23597