Targeting neuropilin-1 in human leukemia and lymphoma

Abstract

Targeted drug delivery offers an opportunity for the development of safer and more effective therapies for the treatment of cancer. In this study, we sought to identify short, cell-internalizing peptide ligands that could serve as directive agents for specific drug delivery in hematologic malignancies. By screening of human leukemia cells with a combinatorial phage display peptide library, we isolated a peptide motif, sequence Phe-Phe/TyrAny-Leu-Arg-Ser (F F / Y XLRS), which bound to different leukemia cell lines and to patient-derived bone marrow samples. The motif was internalized through a receptor-mediated pathway, and we next identified the corresponding receptor as the transmembrane glycoprotein neuropilin-1 (NRP-1). Moreover, we observed a potent anti-leukemia cell effect when the targeting motif was synthesized in tandem to the pro-apoptotic sequence D (KLAKLAK) 2 . Finally, our results confirmed increased expression of NRP-1 in representative human leukemia and lymphoma cell lines and in a panel of bone marrow specimens obtained from patients with acute lymphoblastic leukemia or acute myelogenous leukemia compared with normal bone marrow. These results indicate that NRP-1 could potentially be used as a target for liganddirected therapy in human leukemias and lymphomas and that the prototype CGFYWLRSC-GG-D (KLAKLAK) 2 is a promising drug candidate in this setting. (Blood. 2011;117(3):920-927) IntroductionThe development of targeted drug-delivery strategies for safer and more effective therapy in human hematologic malignancies has been a long-standing goal for clinical and basic investigators. We reasoned that profiling of human leukemia-and lymphoma-derived cell lines with combinatorial libraries might yield ligand peptide sequences that bind to specific internalizing receptors on cell surfaces and may potentially lead to the discovery of new or unrecognized therapeutic targets. Such targeting motifs could also serve as vehicles for the preferential delivery of cytotoxic agents to leukemia and lymphoma cells.Several cell surface-binding peptides recognizing receptors in the membranes of lymphoma and leukemia cell lines have been reported. [1][2][3][4][5] The selected peptide ligands are readily internalized by cells and may therefore be potentially useful in ligand-directed drug delivery. Recently, we described an arginine-rich motif that is internalized into leukemia and lymphoma cells through the macropinocytotic pathway; however, the precise cell surface receptor has yet to be identified. 6 In effect, there is currently a relative lack of well-defined ligand-receptor systems for targeting human leukemia or lymphoma cells. The identification and validation of ligandreceptor pairs for these hematologic cancer cells relative to normal leukocytes would potentially represent a differential strategy and perhaps even improve disease outcomes.In this study, we used a combinatorial phage display-based subtractive selection 7-9 to identify ligand motifs that bind to specific cell surface receptors on human leuk...

Targeted nanoparticle enhanced proapoptotic peptide as potential therapy for glioblastoma

“…The main limitation of these treatments has been that the D [KLA-KLAK] 2 peptide is highly toxic at the doses required for tumor treatment even with specific targeting. The presumed reason is kidney toxicity of the nondegradable D-conformer (13). The vastly enhanced activity of the multimeric CGKRK D [KLA- In contrast, NWs displaying the proapoptotic peptide without CGKRK showed no tumor homing and no effect on tumor growth.…”

“…We made use of this unique ability of CGKRK to reach the mitochondria by using the amphiphilic proapoptotic peptide D [KLAKLAK] 2 as the payload. D [KLAKLAK] 2 has been shown to act on mitochondria, the target of CGKRK (10), and several reports have described the antitumor activities of D [KLAKLAK] 2 (and some other peptides with similar activities), when selectively delivered to a target tissue (11)(12)(13)(14)(15)(27)(28)(29). The main limitation of these treatments has been that the D [KLA-KLAK] 2 peptide is highly toxic at the doses required for tumor treatment even with specific targeting.…”

“…However, when internalized into eukaryotic cells, D [KLAKLAK] 2 disrupts the mitochondrial membrane, which is similar to bacteria membranes, and initiates apoptotic cell death (10). Conjugating D [KLAKLAK] 2 with homing peptides has produced compounds that specifically accumulate at the homing target, causing cell death (11)(12)(13)(14)(15) 2 , however, is a highly toxic compound, even when specifically targeted to tumors (11,13). Administering toxic drugs in a nanoparticle formulation can reduce toxicity.…”

Advanced targeted therapies in cancer: Drug nanocarriers, the future of chemotherapy

“…With the new advances in peptide research, cytotoxic peptide conjugates are being considered as good alternatives to antibodydrug conjugates, combining small peptides (up to 100 times smaller than antibodies) of low cytotoxicity with the ability to selectively bind to overexpressed receptors of some cancer cells, with the cytotoxicity of anticancer drugs. Several interesting cytotoxic peptide conjugates are under clinical trials, but none have been approved by FDA for the clinical use, because some issues, like their short half-lives, still have to be solved [49][50][51][52][53][54]. In both antibodies and peptides, the linker of the conjugates should be stable during blood transportation, intra or extracellularly in the target cells by specific enzymatic or chemical degradation, releasing the active cytotoxic agents into the cancer cells [55,56].…”

Screening Peptides Binding Specifically to Colorectal Cancer Cells from a Phage Random Peptide Library

“…The phage peptide library technique, with features of large capacity, high flux, and convenient operation, has become a powerful tool for screening peptides that specifically bind to cancer cells or tissues (Kehoe et al, 2005). We have successfully screened peptides that specifically bind to different cancer cells (i.e., neuroglioma, lung cancer, nasopharyngeal carcinoma, ovarian cancer, lymphoma) in vitro, which may have potential clinical value for diagnosis and targeted therapy of various cancers (Zhang et al, 2001;Oyama et al, 2003;Lee et al, 2004;Karjalainen et al, 2011;Zhang et al, 2011). In this study we randomly chose 20 clones from an eluate after the 3 rd round of screening in subtraction biopanning for ELISA detection, 5 of which could bind specifically to the colorectal cancer cells LoVo.…”