AMD3100 Conjugates as Components of Targeted Nonviral Gene Delivery Systems: Synthesis and in Vitro Transfection Efficiency of CXCR4-Expressing Cells

siRNA-Encapsulated Biomimetic Liposomes Effectively Inhibit Tumor Cells' Hexosamine Biosynthesis Pathway for Attenuating Hyaluronan Barriers to Pancreatic Cancer Chemotherapy

Pancreatic ductal adenocarcinoma (PDAC) poses significant therapeutic challenges due to excessive hyaluronic acid (HA) accumulation, which impedes drug delivery. Here, we present a targeted approach to reduce HA production by specifically silencing glutamine-fructose-6-phosphate aminotransferase 1 (GFAT1), a key enzyme of the hexosamine biosynthesis pathway (HBP) in pancreatic cancer cells. An engineered liposomal system for siGFAT1 delivery, PMLip@siGFAT1, characterized by macrophage membrane camouflage, LFC131 peptide-mediated targeting, and calcium phosphate (CaP) as the core, was designed to ensure prolonged circulation, enhanced inflamed vascular endothelial penetration, and subsequent effective tumor cell uptake and endosomal escape. Consequently, PMLip@siGFAT1 markedly downregulated the HA level in the PDAC microenvironment, decompressing the tumor vasculature and weakening the stromal barrier, which in turn improved the permeability of chemotherapeutics. In combination with Doxil, PMLip@siGFAT1 demonstrated potent antitumor efficacy with minimal systemic toxicity. Importantly, unlike PEGPH20 (hyaluronidase), PMLip@siGFAT1 reduced tumor invasiveness, while preserving skeletal muscle integrity. These findings highlight that PMLip@siGFAT1 holds great potential to revitalize HA downregulation strategies in pancreatic cancer for enhanced drug delivery and efficacy.

Selective synthesis of an elusive C-functional bis-cyclam and study of its inhibition of the CXCR4 chemokine receptor

This article presents the controlled synthesis of a rare example of C,C'-linked bis-cyclam architecture in mild conditions through the "bis-aminal" route previously used for the advantageous synthesis of cyclam, N- and C-functional cyclams and N,N'-bis-cyclams. Two synthetic pathways were explored with the smart design of α,β-unsaturated ketones or alkyl halides bis-cyclizing agents. The first led to the isolation of a key intermediate for the future design of N-functionalized bis-cyclams, whereas the second allowed the preparation of the targeted C,C'-xylylene-bis-cyclam under mild conditions with decent yield. This compound was then studied as a CXCR4 receptor inhibitor, one of the main applications known for bis-macrocyclic compounds, in particular in the context of HIV (human immunodeficiency virus) infection. Although results demonstrated that its potency is lower (i.e. 137-fold higher IC50) than the gold standard AMD3100 against HIV infection, clear evidence of CXCR4 inhibition is presented, confirming the potential of this novel architecture and related compounds in this research field.

Modified chitosan for effective renal delivery of siRNA to treat acute kidney injury

Acute kidney injury (AKI) is characterized by a sudden decrease in renal function and impacts growing number of people worldwide. RNA interference (RNAi) showed potential to treat diseases with no or limited conventional therapies, including AKI. Suitable carriers are needed to protect and selectively deliver RNAi to target cells to fully explore this therapeutic modality. Here, we report on the synthesis of chitosan modified with α-cyclam-p-toluic acid (C-CS) as a novel siRNA carrier for targeted delivery to injured kidneys. We demonstrate that conjugation of the α-cyclam-p-toluic acid to chitosan imparts the C-CS polymer with targeting and antagonistic properties to cells overexpressing chemokine receptor CXCR4. In contrast, the parent α-cyclam-p-toluic acid showed no such properties. Self-assembled C-CS/siRNA nanoparticles rapidly accumulate in the injured kidneys and show long retention in renal tubules. Apoptosis and metabolic and inflammatory pathways induced by p53 are important pathological mechanisms in the development of AKI. Nanoparticles with siRNA against p53 (sip53) were formulated and intravenously injected for attenuation of IRI-AKI. Due to the favorable accumulation in injured kidneys, the treatment with C-CS/sip53 decreased renal injury, extent of renal apoptosis, macrophage and neutrophil infiltration, and improved renal function. Overall, our study suggests that C-CS/siRNA nanoparticles have the potential to effectively accumulate and deliver therapeutic siRNAs to injured kidneys through CXCR4 binding, providing a novel way for AKI therapy.

Synergistic Anti-Angiogenic Effects Using Peptide-Based Combinatorial Delivery of siRNAs Targeting VEGFA, VEGFR1, and Endoglin Genes

Angiogenesis is a process of new blood vessel formation, which plays a significant role in carcinogenesis and the development of diseases associated with pathological neovascularization. An important role in the regulation of angiogenesis belongs to several key pathways such as VEGF-pathways, TGF-β-pathways, and some others. Introduction of small interfering RNA (siRNA) against genes of pro-angogenic factors is a promising strategy for the therapeutic suppression of angiogenesis. These siRNA molecules need to be specifically delivered into endothelial cells, and non-viral carriers modified with cellular receptor ligands can be proposed as perspective delivery systems for anti-angiogenic therapy purposes. Here we used modular peptide carrier L1, containing a ligand for the CXCR4 receptor, for the delivery of siRNAs targeting expression of VEGFA, VEGFR1 and endoglin genes. Transfection properties of siRNA/L1 polyplexes were studied in CXCR4-positive breast cancer cells MDA-MB-231 and endothelial cells EA.Hy926. We have demonstrated the efficient down-regulation of endothelial cells migration and proliferation by anti-VEGFA, anti-VEGFR1, and anti-endoglin siRNA-induced silencing. It was found that the efficiency of anti-angiogenic treatment can be synergistically improved via the combinatorial delivery of anti-VEGFA and anti-VEGFR1 siRNAs. Thus, this approach can be useful for the development of therapeutic angiogenesis inhibition.

VEGFA Gene Silencing in CXCR4-Expressing Cells via siRNA Delivery by Means of Targeted Peptide Carrier

Discovery of small interfering RNA as a tool for specific gene inhibition led to the development of new therapeutic strategy for the treatment of cancers. The efficacious delivery of therapeutic siRNAs into the cells is a crucial step in RNA interference (RNAi) application, but it remains challenging. Non-viral vectors can provide specific cellular uptake, stable siRNA complex formation, and intracellular siRNA release. Recently, we evaluated modular peptide carrier L1 bearing CXCR4 targeting ligand for its ability to condense siRNA and facilitate endosomal escape and VEGFA gene silencing in CXCR4-expressing endothelial and glioblastoma cells. The present chapter showcases the ability of L1 targeted peptide carrier to form complexes with siRNA and provide efficient VEGFA gene knockdown. We showed that siRNA delivery by means of L1 peptide carrier can result in significant decrease of VEGFA gene expression in A172 glioblastoma cells and in EA.hy 926 endothelial cells. Also, delivery of anti-VEGFA siRNA/peptide complexes led to significant inhibition of endothelial cell migration. Our results showed that L1 peptide carrier modified with CXCR4 ligand is a promising tool for targeted siRNA delivery into CXCR4-expressing cancer and endothelial cells.

Potential of CXCR4/CXCL12 Chemokine Axis in Cancer Drug Delivery

This review discusses the potential of CXCR4 chemokine receptor in the design of anticancer and antimetastatic drug delivery systems. The role of CXCR4 in cancer progression and metastasis is discussed in the context of the development of several types of drug delivery strategies. Overview of drug delivery systems targeted to cancers that overexpress CXCR4 is provided, together with the main types of CXCR4-binding ligands used in targeting applications. Drug delivery applications that take advantage of CXCR4 inhibition to achieve enhanced anticancer and antimetastatic activity of combination treatments are also discussed.

CXCR-4 Targeted, Short Wave Infrared (SWIR) Emitting Nanoprobes for Enhanced Deep Tissue Imaging and Micrometastatic Cancer Lesion Detection

Realizing the promise of precision medicine in cancer therapy depends on identifying and tracking cancerous growths to maximize treatment options and improve patient outcomes. This goal of early detection remains unfulfilled by current clinical imaging techniques that fail to detect lesions due to their small size and suborgan localization. With proper probes, optical imaging techniques can overcome this by identifying the molecular phenotype of tumors at both macroscopic and microscopic scales. In this study, the first use of nanophotonic short wave infrared technology is proposed to molecularly phenotype small lesions for more sensitive detection. Here, human serum albumin encapsulated rare-earth nanoparticles (ReANCs) with ligands for targeted lesion imaging are designed. AMD3100, an antagonist to CXCR4 (a classic marker of cancer metastasis) is adsorbed onto ReANCs to form functionalized ReANCs (fReANCs). fReANCs are able to preferentially accumulate in receptor positive lesions when injected intraperitoneally in a subcutaneous tumor model. fReANCs can also target subtissue microlesions at a maximum depth of 10.5 mm in a lung metastatic model of breast cancer. Internal lesions identified with fReANCs are 2.25 times smaller than those detected with ReANCs. Thus, an integrated nanoprobe detection platform is presented, which allows target-specific identification of subtissue cancerous lesions.

CXCR4-Targeted Nanocarriers for Triple Negative Breast Cancers

CXCR4 is a cell membrane receptor that is overexpressed in triple-negative breast cancers and implicated in growth and metastasis of this disease. Using electrohydrodynamic cojetting, we prepared multicompartmental drug delivery carriers for CXCR4 targeting. The particles are comprised of a novel poly(lactide-co-glycolide) derivative that allows for straightforward immobilization of 1,1'-[1,4-phenylenebis(methylene)]bis[1,4,8,11-tetraazacyclotetradecane] (Plerixafor), a small molecule with affinity for CXCR4. Targeted nanocarriers are selectively taken up by CXCR4-expressing cells and effectively block CXCR4 signaling. This study suggests that CXCR4 may be an effective target for nanocarrier-based therapies.

Dual-function CXCR4 antagonist polyplexes to deliver gene therapy and inhibit cancer cell invasion

A bicyclam-based biodegradable polycation with CXCR4 antagonistic activity was developed with potential for combined drug/gene cancer therapies. The dual-function polycation prevents cancer cell invasion by inhibiting CXCL12 stimulated CXCR4 activation, while at the same time efficiently and safely delivers plasmid DNA into cancer cells.

Chemokine-derived peptides as carriers for gene delivery to CXCR4 expressing cells

BACKGROUND

Cell and tissue-specific DNA delivery can be achieved by derivatizing vehicles with a targeting ligand for certain receptor. CXCR4 is a receptor of chemokine stromal cell-derived factor (SDF)-1 and viral protein viral macrophage inflammatory protein (vMIP)-II. It is expressed on some types of stem and cancer cells. The present study aimed to design and characterize the group of CXCR4 targeted peptides for receptor-mediated gene delivery. We focused on bifunctional peptide carriers: two derived from N-terminal sequences of SDF-1 and one from vMIP-II.

METHODS

Three synthetic chemokine-derived peptides, designated long CDP (KPVSLSYRSPSRFFESH-K9-biotin), short CDP (KPVSLSYR-K9-biotin) and viral CDP (D-LGASWHRPDK-K9-biotin), were evaluated for gene delivery to CXCR4 positive and negative cells. Oligolysine K9-biotin was used as a control. The Lys 8 moiety binds DNA electrostatically, whereas C-terminal lysine was modified with biotin to study intracellular uptake of the peptides. Complex formation with DNA was monitored by ethidium bromide fluorescence quenching.

RESULTS

All peptides condensed plasmid DNA. Gene delivery by CDP/DNA complexes is glycerol-dependent and the level of luciferase expression with signal modified carriers was comparable with the efficacy of polyethylenimine (PEI) in CXCR4 expressing cell lines (A172, HeLa) and was ten- to 50-fold higher compared to unmodified peptide. By contrast, CDP transfection efficacy on CXCR4-negative cells (chinese hamster ovary) was much lower than in PEI. Intracellular uptake analysis of biotin-labeled peptides indicated that CDPs entered cells more efficiently than oligolysine.

CONCLUSIONS

The small, bifunctional peptides reported in the present study may be useful in gene delivery to (and gene therapy of) the different tumors and other cells expressing CXCR4.