Molecularly targeted nanocarriers deliver the cytolytic peptide melittin specifically to tumor cells in mice, reducing tumor growth
Neelesh R. Soman, … , Samuel A. Wickline, Paul H. Schlesinger
Neelesh R. Soman, … , Samuel A. Wickline, Paul H. Schlesinger
Published August 10, 2009
Citation Information: J Clin Invest. 2009;119(9):2830-2842. https://doi.org/10.1172/JCI38842.
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Technical Advance Oncology

Molecularly targeted nanocarriers deliver the cytolytic peptide melittin specifically to tumor cells in mice, reducing tumor growth

Abstract

The in vivo application of cytolytic peptides for cancer therapeutics is hampered by toxicity, nonspecificity, and degradation. We previously developed a specific strategy to synthesize a nanoscale delivery vehicle for cytolytic peptides by incorporating the nonspecific amphipathic cytolytic peptide melittin into the outer lipid monolayer of a perfluorocarbon nanoparticle. Here, we have demonstrated that the favorable pharmacokinetics of this nanocarrier allows accumulation of melittin in murine tumors in vivo and a dramatic reduction in tumor growth without any apparent signs of toxicity. Furthermore, direct assays demonstrated that molecularly targeted nanocarriers selectively delivered melittin to multiple tumor targets, including endothelial and cancer cells, through a hemifusion mechanism. In cells, this hemifusion and transfer process did not disrupt the surface membrane but did trigger apoptosis and in animals caused regression of precancerous dysplastic lesions. Collectively, these data suggest that the ability to restrain the wide-spectrum lytic potential of a potent cytolytic peptide in a nanovehicle, combined with the flexibility of passive or active molecular targeting, represents an innovative molecular design for chemotherapy with broad-spectrum cytolytic peptides for the treatment of cancer at multiple stages.

Authors

Neelesh R. Soman, Steven L. Baldwin, Grace Hu, Jon N. Marsh, Gregory M. Lanza, John E. Heuser, Jeffrey M. Arbeit, Samuel A. Wickline, Paul H. Schlesinger

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Figure 5

Release of cytochrome c (cyt c) and induction of apoptosis by αvβ3 integrin–targeted melittin-loaded nanoparticles.

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Release of cytochrome c (cyt c) and induction of apoptosis by αvβ3 integ...
(A) Effect of αvβ3 targeting on the association of fluorescein-melittin with C32 melanoma cells in culture visualized by confocal microscopy. Cells were exposed to fluorescein-melittin at 37°C. Scale bar: 20 μm. (B) A single C32 melanoma cell reconstruction using the T3D package in NEOSYS. This allows viewing both the cell surface and intracellular distribution of the fluorescein-melittin after incubation at 37°C. (C) C32 melanoma cells were treated with the indicated concentration of melittin on αvβ3 integrin–targeted nanoparticles. Apoptosis was determined by flow cytometry. Cells stained with annexin V–FITC only were considered early in apoptosis and those stained with annexin V–FITC and 7-AAD were late apoptotic cells. Data are represented as mean ± SD. n = 3. (D) Comparison of cytochrome c release from mitochondria and extracellular release of LDH. Data are represented as mean ± SD. n = 3. *P < 0.05; **P < 0.01.