title: Combinatorial targeting of the macropinocytotic pathway in leukemia and lymphoma cells.
abstract: Ligand-directed delivery of agents to leukemia and lymphoma cells has the potential to yield new mechanistic disease insights and targeted therapies. Here we set out to target the macropinocytotic pathway with a combinatorial approach. From the screening of acute T-lymphoblastic leukemia Molt-4 cells with a random phage-display peptide library, we isolated a phage displaying the sequence CAYHRLRRC. This peptide contains a lymph node-homing motif (Cys-Ala-Tyr) and a cell-penetrating motif (Arg-Leu-Arg-Arg). Binding of this ligand-directed phage to a large panel of leukemia/lymphoma cells and to patient-derived samples was much higher than to non-leukemia control cells. CAYHRLRRC phage internalization into Molt-4 cells is both energy- and temperature-dependent. Flow cytometry with fluorescein-labeled peptide and endocytosis blocking with specific inhibitors revealed that CAYHRLRRC is indeed taken up through macropinocytosis in Molt-4 and K562 human leukemia cells. Unexpectedly, the cell surface receptor for the CAYHRLRRC peptide is not a heparan sulfate proteoglycan as it would be predicted for other cell-penetrating peptides. Confirming this interpretation, a CAYHRLRRC-directed peptidomimetic-induced cell death in all the leukemia and lymphoma cells was evaluated, whereas a control transactivator of transcription protein (tat)-directed proapoptotic peptidomimetic was non-selective. In summary, the targeting peptide CAYHRLRRC is selectively internalized through macropinocytosis in leukemia and lymphoma cells and has potential as a drug lead for ligand-directed anti-leukemia therapies.
authors.affiliation: Department of Molecular Cell Function, Graduate School of Medical and Pharmaceutical Sciences, Kumamoto University, 5-1 Ohe-honmachi, Kumamoto 862-0973, Japan.
authors.forename: Shinpei
authors.initials: S
authors.lastname: Nishimura
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Takahashi
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kamikatahira
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kuroki
authors.forename: Diana E
authors.initials: DE
authors.lastname: Jaalouk
authors.forename: Susan
authors.initials: S
authors.lastname: O'Brien
authors.forename: Erkki
authors.initials: E
authors.lastname: Koivunen
authors.forename: Wadih
authors.initials: W
authors.lastname: Arap
authors.forename: Renata
authors.initials: R
authors.lastname: Pasqualini
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nakayama
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kuniyasu
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002384:Catalysis; D045744:Cell Line, Tumor; D002470:Cell Survival; D002626:Chemistry, Pharmaceutical / Q000379:methods; D015195:Drug Design; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D020014:K562 Cells; D007938:Leukemia / Q000378:metabolism*; D008024:Ligands; D008223:Lymphoma / Q000378:metabolism*; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry; D010873:Pinocytosis
chemical_list: D000970:Antineoplastic Agents; D008024:Ligands; D019151:Peptide Library; D010455:Peptides