Chloroquine-Modified Hydroxyethyl Starch as a Polymeric Drug for Cancer Therapy

Hydroxyethyl starch (HES) is a clinically used polysaccharide colloidal plasma volume expander. The goal of this study was to synthesize HES modified with hydroxychloroquine (HCQ) as a novel polymeric drug with the ability to inhibit the invasive character of pancreatic cancer (PC) cells. HES was conjugated with HCQ using a simple carbonyldiimidazole coupling to prepare Chloroquine-modified HES (CQ-HES). CQ-HES with various degrees of HCQ substitution were synthesized and characterized. Atomic force microscopy was used to demonstrate a pH-dependent assembly of CQ-HES into well-defined nanoparticles. <i>In vitro</i> studies in multiple PC cell lines showed CQ-HES to have a similar toxicity profile as HCQ. Confocal microscopy revealed the propensity of CQ-HES to localize to lysosomes and mechanistic studies confirmed the ability of CQ-HES to inhibit autophagy in PC cells. Further studies demonstrated a greatly enhanced ability of CQ-HES to inhibit the migration and invasion of PC cells when compared with HCQ. The enhanced inhibitory actions of CQ-HES compared to HCQ appeared to arise in part from the increased inhibition of ERK and Akt phosphorylation. We found no significant HCQ release from CQ-HES, which confirmed that the observed activity was due to the action of CQ-HES as a polymeric drug. Due to its promising ability to block cancer cell invasion and the ability to form nanoparticles, CQ-HES has the potential as a drug delivery platform suitable for future development with chemotherapeutics to establish novel antimetastatic treatments

Dual-Function Polymeric HPMA Prodrugs for the Delivery of miRNA

An HPMA-based polymeric prodrug of a CXCR4 antagonist, AMD3465 (P-SS-AMD), was developed as a dual-function carrier of therapeutic miRNA. P-SS-AMD was synthesized by a copolymerization of HPMA with a methacrylamide monomer in which the AMD3465 was attached via a self-immolative disulfide linker. P-SS-AMD showed effective release of the parent AMD3465 drug following treatment with intracellular levels of glutathione (GSH). The AMD3465 was released in the cells and exhibited functional CXCR4 antagonism, demonstrated by inhibition of the CXCR4-mediated cancer cell invasion. Due to its cationic character, P-SS-AMD could form polyplexes with miRNA and mediate efficient transfection of miR-200c mimics to downregulate expression of a downstream target ZEB-1 in cancer cells. The combined P-SS-AMD/miR-200c polyplexes showed improved ability to inhibit cancer cell migration when compared with individual treatments. The reported findings validate P-SS-AMD as a dual-function delivery vector that can simultaneously deliver a therapeutic miRNA and function as a polymeric prodrug of CXCR4 antagonist

Chloroquine-Containing HPMA Copolymers as Polymeric Inhibitors of Cancer Cell Migration Mediated by the CXCR4/SDF‑1 Chemokine Axis

Chloroquine-containing HPMA copolymers (pCQs) were synthesized for the first time by copolymerization of methacryloylated hydroxychloroquine and HPMA. The copolymers showed lower cytotoxicity when compared with hydroxychloroquine. Treatment of cancer cells with pCQ resulted in decreased surface expression of chemokine receptor CXCR4. The pCQ copolymers showed effective inhibition of CXCR4/SDF1-mediated cancer cell migration that was fully comparable with a commercial small-molecule CXCR4 antagonist AMD3100. The reported pCQ represent unique and simple polymeric drugs with potential use as part of a combination antimetastatic therapies

Self-Immolative Polycations as Gene Delivery Vectors and Prodrugs Targeting Polyamine Metabolism in Cancer

Polycations are explored as carriers to deliver therapeutic nucleic acids. Polycations are conventionally pharmacological inert with the sole function of delivering therapeutic cargo. This study reports synthesis of a self-immolative polycation (DSS-BEN) based on a polyamine analogue drug <i>N</i>¹,<i>N</i>¹¹-bisethylnorspermine (BENSpm). The polycation was designed to function dually as a gene delivery carrier and a prodrug targeting dysregulated polyamine metabolism in cancer. Using a combination of NMR and HPLC, we confirm that the self-immolative polycation undergoes intracellular degradation into the parent drug BENSpm. The released BENSpm depletes cellular levels of spermidine and spermine and upregulates polyamine catabolic enzymes spermine/spermidine <i>N</i>¹-acetyltransferase (SSAT) and spermine oxidase (SMO). The synthesized polycations form polyplexes with DNA and facilitate efficient transfection. Taking advantage of the ability of BENSpm to sensitize cancer cells to TNFα-induced apoptosis, we show that DSS-BEN enhances the cell killing activity of TNFα gene therapy. The reported findings validate DSS-BEN as a dual-function delivery system that can deliver a therapeutic gene and improve the outcome of gene therapy as a result of the intracellular degradation of DSS-BEN to BENSpm and the subsequent beneficial effect of BENSpm on dysregulated polyamine metabolism in cancer

Polymeric Chloroquine as an Effective Antimigration Agent in the Treatment of Pancreatic Cancer

Hydroxychloroquine (HCQ) has been the subject of multiple recent preclinical and clinical studies for its beneficial use in the combination treatments of different types of cancers. Polymeric HCQ (PCQ), a macromolecular multivalent version of HCQ, has been shown to be effective in various cancer models both in vitro and in vivo as an inhibitor of cancer cell migration and experimental lung metastasis. Here, we present detailed in vitro studies that show that low concentrations of PCQ can efficiently inhibit cancer cell migration and colony formation orders of magnitude more effectively compared to HCQ. After intraperitoneal administration of PCQ in vivo, high levels of tumor accumulation and penetration are observed, combined with strong antimetastatic activity in an orthotopic pancreatic cancer model. These studies support the idea that PCQ may be effectively used at low doses as an adjuvant in the therapy of pancreatic cancer. In conjunction with previously published literature, these studies further undergird the potential of PCQ as an anticancer agent

Tumor-Penetrating Nanoparticles for Enhanced Anticancer Activity of Combined Photodynamic and Hypoxia-Activated Therapy

Poor tumor penetration is a major challenge for the use of nanoparticles in anticancer therapy. Moreover, the inability to reach hypoxic tumor cells that are distant from blood vessels results in inadequate exposure to antitumor therapeutics and contributes to development of chemoresistance and increased metastasis. In the present study, we developed iRGD-modified nanoparticles for simultaneous tumor delivery of a photosensitizer indocyanine green (ICG) and hypoxia-activated prodrug tirapazamine (TPZ). The iRGD-modified nanoparticles loaded with ICG and TPZ showed significantly improved penetration in both 3D tumor spheroids <i>in vitro</i> and orthotopic breast tumors <i>in vivo</i>. ICG-mediated photodynamic therapy upon irradiation with a near-IR laser induced hypoxia, which activated antitumor activity of the codelivered TPZ for synergistic cell-killing effect. <i>In vivo</i> studies demonstrated that the nanoparticles could efficiently deliver the drug combination in 4T1 orthotopic tumors. Primary tumor growth and metastasis were effectively inhibited by the iRGD-modified combination nanoparticles with minimal side effects. The results also showed the anticancer benefits of codelivering ICG and TPZ in a single nanoparticle formulation in contrast to a mixture of nanoparticles containing individual drugs. The study demonstrates the benefits of combining tumor-penetrating nanoparticles with hypoxia-activated drug treatment and establishes a delivery platform for PDT and hypoxia-activated chemotherapy

Oral Nanostructured Lipid Carriers Loaded with Near-Infrared Dye for Image-Guided Photothermal Therapy

Photothermal therapy exerts its anticancer effect by converting laser radiation energy into hyperthermia using a suitable photosensitizer. This study reports development of nanostructured lipid carriers (NLCs) suitable for noninvasive oral delivery of a near-infrared photosensitizer dye IR780. The carrier encapsulating the dye (IR780@NLCs) was stable in simulated gastric and intestinal conditions and showed greatly enhanced oral absorption of IR780 when compared with the free dye. As a result of increased oral bioavailability, enhanced accumulation of the dye in subcutaneous mouse colon tumors (CT-26 cells) was observed following oral gavage of IR780@NLCs. Photothermal antitumor activity of orally administered IR780@NLCs was evaluated following local laser irradiation of the CT-26 tumors. We observed significant effect of the photothermal IR780@NLCs treatment on the rate of the tumor growth and no toxicity associated with the oral administration of IR780@NLCs. Overall, orally administered IR780@NLCs represents a safe and noninvasive method to achieve systemic tumor delivery of a photosensitizing dye for applications in photothermal anticancer therapies