It is a central idea of the NIH that basic research will lead to new approaches in medicine, and we believe that we have found one. As a result of earlier funding of this grant, we have discovered a peptide that (1) targets acidic tissues in vivo, including tumors, (2) can deliver polar molecules into cells, releasing them in the cytoplasm, and (3) gives an opportunity to better understand how peptides can insert across membranes. We now plan to explore both the basic and applied aspects of this discovery. The peptide, which we call "pHLIP" (for pH (Low) Insertion Peptide) is soluble as an unstructured monomer in aqueous solution, binds as an unstructured monomer to the surface of a bilayer or membrane, and inserts across the bilayer as a trans-membrane helix (TM) when the pH is lowered. We have established the basic energetics and kinetics of peptide insertion. We have shown that a labeled version of pHLIP targets and images tumors as small as 1 mm in mice, and that the imaging accurately identifies tumor borders. We have also established that large, polar cargo molecules (M ~ 1000 Da, log P ~ -2) attached to the inserting end of pHLIP by a disulfide are delivered across membranes and released in the cytoplasms of cultured tumor cells at low pH. By continuing our basic research we hope to frame the technology for use in the clinic. We will study the process of and sequence requirements for insertion of water soluble peptides into membranes, find improved ways to target tumors and other acidic tissues, and develop expanded ways to deliver polar molecules into cells, releasing them into the cytoplasm by disulfide or ester cleavage. Targeting imaging agents to tumors with pHLIP could aid in diagnosis or act as a guide for surgery, and delivering therapeutics could assist in treatment. Using biophysical, biochemical, and biological approaches, we will seek answers to the following questions: 1. What are the kinetic intermediates, energetics and structures of the bilayer and peptide during insertion? 2. Which sequence features allow a water-soluble peptide to insert spontaneously to form a TM? 3. What role(s) do lipids play in TM insertion? 4. Can pHLIP be used to image cargo delivery in vivo? 5. What is the range of polar molecules that can be delivered to cells?

Public Health Relevance

to Public Health We have discovered a new way to target tumors based on their acidity, using a small peptide that inserts across the membranes of the cells in the tissue. The peptide accumulates preferentially in the tumor, which is acidic as a result of its metabolism, and we can put a label on the peptide to image the tumor for diagnosis or to assist a surgeon in removing it by showing where its boundaries are. The peptide can also be used to deliver drugs into the cells of the tumor, so improved therapy might be possible.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Biochemistry and Biophysics of Membranes Study Section (BBM)
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Chin, Jean
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Yale University
Schools of Medicine
New Haven
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Cheng, Christopher J; Bahal, Raman; Babar, Imran A et al. (2015) MicroRNA silencing for cancer therapy targeted to the tumour microenvironment. Nature 518:107-10
Kohlway, Andrew; Pirakitikulr, Nathan; Barrera, Francisco N et al. (2014) Hepatitis C virus RNA replication and virus particle assembly require specific dimerization of the NS4A protein transmembrane domain. J Virol 88:628-42
Cruz-Monserrate, Zobeida; Roland, Christina L; Deng, Defeng et al. (2014) Targeting pancreatic ductal adenocarcinoma acidic microenvironment. Sci Rep 4:4410
Andreev, Oleg A; Engelman, Donald M; Reshetnyak, Yana K (2014) Targeting diseased tissues by pHLIP insertion at low cell surface pH. Front Physiol 5:97
Adochite, Ramona-Cosmina; Moshnikova, Anna; Carlin, Sean D et al. (2014) Targeting breast tumors with pH (low) insertion peptides. Mol Pharm 11:2896-905
Li, Na; Yin, Lu; Thevenin, Damien et al. (2013) Peptide targeting and imaging of damaged lung tissue in influenza-infected mice. Future Microbiol 8:257-69
Sosunov, Eugene A; Anyukhovsky, Evgeny P; Sosunov, Alexander A et al. (2013) pH (low) insertion peptide (pHLIP) targets ischemic myocardium. Proc Natl Acad Sci U S A 110:82-6
Weerakkody, Dhammika; Moshnikova, Anna; Thakur, Mak S et al. (2013) Family of pH (low) insertion peptides for tumor targeting. Proc Natl Acad Sci U S A 110:5834-9
Macholl, Sven; Morrison, Matthew S; Iveson, Peter et al. (2012) In vivo pH imaging with (99m)Tc-pHLIP. Mol Imaging Biol 14:725-34
Matthews, Erin E; Thevenin, Damien; Rogers, Julia M et al. (2011) Thrombopoietin receptor activation: transmembrane helix dimerization, rotation, and allosteric modulation. FASEB J 25:2234-44

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