pHLIP-FIRE, a Cell Insertion-Triggered Fluorescent Probe for Imaging Tumors Demonstrates Targeted Cargo Delivery <i>In Vivo</i>

Karabadzhak, Alexander G.; An, Ming; Yao, Lan; Langenbacher, Rachel E; Moshnikova, Anna; Adochite, Ramona-Cosmina; Andreev, Oleg A.; Reshetnyak, Yana K.; Engelman, Donald M.

doi:10.1021/cb500388m

Cited by 32 publications

(30 citation statements)

References 25 publications

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“…This linking strategy allows for the release of MMAE into the cytoplasm of cancer cells after translocation and reduction of the disulfide bond (Figure 1B). 19,25 Cleavage of the disulfide bond results in release of an N-terminally modified form of MMAE (Figure 1B). The resulting MMAE derivative and the parental MMAE exhibit IC50 ~ 125 nM and 4 nM against HeLa cells, respectively, when incubated with the cells for 72 hours (Figure S1).…”

Section: Resultsmentioning

confidence: 99%

Inhibition of Cancer Cell Proliferation and Breast Tumor Targeting of pHLIP–Monomethyl Auristatin E Conjugates

2015

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Localized delivery is vital for the successful development of novel and effective therapeutics for the treatment of cancer. The targeting and delivery described herein is based on the pH(Low) Insertion Peptide (pHLIP), a unique delivery peptide that can selectively target tumors in mice and translocate and release cargo molecules intra-cellularly based solely on the low extracellular pH intrinsic to cancer cells. In this study, we investigate the efficacy of pHLIP to target and deliver the highly potent and clinically validated microtubule inhibitor monomethyl auristatin E (MMAE) to cancer cells and breast tumors. We show that pHLIP-MMAE conjugates induce a potent cytotoxic effect (> 90% inhibition of cell growth) in a concentration- and pH-dependent manner after only 2-hour incubation without any apparent disruption of the plasma membrane. pHLIP-MMAE conjugates exhibit between an 11 and 144-fold higher anti-proliferative effect at low pH than at physiological pH, and a pronounced pH-dependent cytotoxicity as compared to free drug. Furthermore, we demonstrate that a pHLIP-MMAE drug conjugate effectively targets triple negative breast tumor xenografts in mice. These results indicate pHLIP-based auristatin conjugates may have an enhanced therapeutic window as compared to free drug, providing a targeting mechanism to attenuate systemic toxicity.

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Section: Resultsmentioning

confidence: 99%

Inhibition of Cancer Cell Proliferation and Breast Tumor Targeting of pHLIP–Monomethyl Auristatin E Conjugates

2015

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“…The molecular mechanism of a pHLIP action is based on the protonation of Asp/Glu residues, which enhances peptide hydrophobicity and promotes membrane-associated folding and insertion of a transmembrane helix (28,29). pHLIPs labeled with optical, PET or single-photon emission computed tomography probes target acidic diseased tissue and are considered to be novel acidity markers (30)(31)(32)(33)(34)(35)(36)(37). The tool we present here for measuring the pH at the extracellular surface of a cell might contribute to understanding disease progression and to the development of approaches using pH-based, image-guided interventions.…”

Section: Significancementioning

confidence: 99%

Probe for the measurement of cell surface pH in vivo and ex vivo

Anderson

Moshnikova

Engelman

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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179

153

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We have developed a way to measure cell surface pH by positioning a pH-sensitive fluorescent dye, seminaphtharhodafluor (SNARF), conjugated to the pH low insertion peptide (pHLIP). It has been observed that many diseased tissues are acidic and that tumors are especially so. A combination of effects acidifies tumor cell interiors, and cells pump out lactic acid and protons to maintain intracellular pH, acidifying the extracellular space. Overexpression of carbonic anhydrases on cell surfaces further contributes to acidification. Thus, the pH near tumor cell surfaces is expected to be low and to increase with distance from the membrane, so bulk pH measurements will not report surface acidity. Our new surface pH-measurement tool was validated in cancer cells grown in spheroids, in mouse tumor models in vivo, and in excised tumors. We found that the surface pH is sensitive to cell glycolytic activity: the pH decreases in high glucose and increases if glucose is replaced with nonmetabolized deoxyglucose. For highly metastatic cancer cells, the pH measured at the surface was 6.7–6.8, when the surrounding external pH was 7.4. The approach is sensitive enough to detect 0.2–0.3 pH unit changes in vivo in tumors induced by i.p. injection of glucose. The pH at the surfaces of highly metastatic cells within tumors was found to be about 6.1–6.4, whereas in nonmetastatic tumors, it was 6.7–6.9, possibly creating a way to distinguish more aggressive from less aggressive tumors. Other biological roles of surface acidity may be found, now that targeted measurements are possible.

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“…Strategies are described aiming at increasing peptide selectivity toward specific cells, while reducing toxicity [162]. Improvements in drug delivery associated with cancer-targeting peptides have also been reported [165][166][167][168][169][170][171].…”

Section: Anticancer Potentialmentioning

confidence: 99%

Latarcins: versatile spider venom peptides

Dubovskii

Vassilevski

Kozlov

et al. 2015

Cell. Mol. Life Sci.

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Arthropod venoms feature the presence of cytolytic peptides believed to act synergetically with neurotoxins to paralyze prey or deter aggressors. Many of them are linear, i.e., lack disulfide bonds. When isolated from the venom, or obtained by other means, these peptides exhibit common properties. They are cationic; being mostly disordered in aqueous solution, assume amphiphilic α-helical structure in contact with lipid membranes; and exhibit general cytotoxicity, including antifungal, antimicrobial, hemolytic, and anticancer activities. To suit the pharmacological needs, the activity spectrum of these peptides should be modified by rational engineering. As an example, we provide a detailed review on latarcins (Ltc), linear cytolytic peptides from Lachesana tarabaevi spider venom. Diverse experimental and computational techniques were used to investigate the spatial structure of Ltc in membrane-mimicking environments and their effects on model lipid bilayers. The antibacterial activity of Ltc was studied against a panel of Gram-negative and Gram-positive bacteria. In addition, the action of Ltc on erythrocytes and cancer cells was investigated in detail with confocal laser scanning microscopy. In the present review, we give a critical account of the progress in the research of Ltc. We explore the relationship between Ltc structure and their biological activity and derive molecular characteristics, which can be used for optimization of other linear peptides. Current applications of Ltc and prospective use of similar membrane-active peptides are outlined.

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pHLIP-FIRE, a Cell Insertion-Triggered Fluorescent Probe for Imaging Tumors Demonstrates Targeted Cargo Delivery In Vivo

Cited by 32 publications

References 25 publications

Inhibition of Cancer Cell Proliferation and Breast Tumor Targeting of pHLIP–Monomethyl Auristatin E Conjugates

Inhibition of Cancer Cell Proliferation and Breast Tumor Targeting of pHLIP–Monomethyl Auristatin E Conjugates

Probe for the measurement of cell surface pH in vivo and ex vivo

Latarcins: versatile spider venom peptides

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