Rang Woon Park

Hydrophobically modified glycol chitosan nanoparticles-encapsulated camptothecin enhance the drug stability and tumor targeting in cancer therapy

To prepare a water-insoluble camptothecin (CPT) delivery carrier, hydrophobically modified glycol chitosan (HGC) nanoparticles were constructed by chemical conjugation of hydrophobic 5beta-cholanic acid moieties to the hydrophilic glycol chitosan backbone. Insoluble anticancer drug, CPT, was easily encapsulated into HGC nanoparticles by a dialysis method and the drug loading efficiency was above 80%. CPT-encapsulated HGC (CPT-HGC) nanoparticles formed nano-sized self-aggregates in aqueous media (280-330 nm in diameter) and showed sustained release of CPT for 1 week. Also, HGC nanoparticles effectively protected the active lactone ring of CPT from the hydrolysis under physiological condition, due to the encapsulation of CPT into the hydrophobic cores in the HGC nanoparticles. The CPT-HGC nanoparticles exhibited significant antitumor effects and high tumor targeting ability towards MDA-MB231 human breast cancer xenografts subcutaneously implanted in nude mice. Tumor growth was significantly inhibited after i.v. injection of CPT-HGC nanoparticles at doses of 10 mg/kg and 30 mg/kg, compared to free CPT at dose of 30 mg/kg. The significant antitumor efficacy of CPT-HGC nanoparticles was attributed to the ability of the nanoparticles to show both prolonged blood circulation and high accumulation in tumors, as confirmed by near infrared (NIR) fluorescence imaging systems. Thus, the delivery of CPT to tumor tissues at a high concentration, with the assistance of HGC nanoparticles, exerted a potent therapeutic effect. These results reveal the promising potential of HGC nanoparticles-encapsulated CPT as a stable and effective drug delivery system in cancer therapy.

Antitumor efficacy of cisplatin-loaded glycol chitosan nanoparticles in tumor-bearing mice

To make a tumor targeting nano-sized drug delivery system, biocompatible and biodegradable glycol chitosan (M(w)=250 kDa) was modified with hydrophobic cholanic acid. The resulting hydrophobically modified glycol chitosans (HGCs) that formed nano-sized self-aggregates in an aqueous medium were investigated as an anticancer drug carrier in cancer treatment. Insoluble anticancer drug, cisplatin (CDDP), was easily encapsulated into the hydrophobic cores of HGC nanoparticles by a dialysis method, wherein the drug loading efficiency was about 80%. The CCDP-encapsulated HGC (CDDP-HGC) nanoparticles were well-dispersed in aqueous media and they formed a nanoparticles structure with a mean diameter about 300-500 nm. As a nano-sized drug carrier, the CDDP-HGC nanoparticles released the drug in a sustained manner for a week and they were also less cytotoxic than was free CDDP, probably because of sustained release of CDDP from the HGC nanoparticles. The tumor targeting ability of CDDP-HGC nanoparticles was confirmed by in vivo live animal imaging with near-infrared fluorescence Cy5.5-labeled CDDP-HGC nanoparticles. It was observed that CDDP-HGC nanoparticles were successfully accumulated by tumor tissues in tumor-bearing mice, because of the prolonged circulation and enhanced permeability and retention (EPR) effect of CDDP-HGC nanoparticles in tumor-bearing mice. As expected, the CDDP-HGC nanoparticles showed higher antitumor efficacy and lower toxicity compared to free CDDP, as shown by changes in tumor volumes, body weights, and survival rates, as well as by immunohistological TUNEL assay data. Collectively, the present results indicate that HGC nanoparticles are a promising carrier for the anticancer drug CDDP.

Tumor-homing multifunctional nanoparticles for cancer theragnosis: Simultaneous diagnosis, drug delivery, and therapeutic monitoring.

Theragnostic multifunctional nanoparticles hold great promise in simultaneous diagnosis of disease, targeted drug delivery with minimal toxicity, and monitoring of treatment. One of the current challenges in cancer treatment is enhancing the tumor-specific targeting of both imaging probes and anticancer agents. Herein, we report tumor-homing chitosan-based nanoparticles (CNPs) that simultaneously execute cancer diagnosis and therapy (cancer theragnosis). These CNPs are unique for their three distinctive characteristics, such as stability in serum, deformability, and rapid uptake by tumor cells. These properties are critical in increasing their tumor targeting specificity and reducing their nonspecific uptake by normal tissues. To develop these CNPs into novel theragnostic nanoparticles, we labeled them with Cy5.5, a near-infrared fluorescent (NIRF) dye, for imaging and also loaded them with paclitaxel (PTX-CNPs), an anticancer drug, for cancer treatment. Cy5.5 labeled PTX-CNPs exhibited significantly increased tumor-homing ability with low nonspecific uptake by other tissues in SCC7 tumor-bearing mice. Theragnostic nanoparticles, Cy5.5 labeled PTX-CNPs, are highly useful for simultaneous diagnosis of early-stage cancer and drug delivery.

Self-assembled glycol chitosan nanoparticles for the sustained and prolonged delivery of antiangiogenic small peptide drugs in cancer therapy.

Antiangiogenic peptide drugs have received much attention in the fields of tumor therapy and tumor imaging because they show promise in the targeting of integrins such as alpha(v)beta(3) on angiogenic endothelial cells. However, systemic antiangiogenic peptide drugs have short half-lives in vivo, resulting in fast serum clearance via the kidney, and thus the therapeutic effects of such drugs remain modest. In this study, we prepared self-assembled glycol chitosan nanoparticles and explored whether this construct might function as a prolonged and sustained drug delivery system for RGD peptide, used as an antiangiogenic model drug in cancer therapy. Glycol chitosan hydrophobically modified with 5beta-cholanic acid (HGC) formed nanoparticles with a diameter of 230 nm, and RGD peptide was easily encapsulated into HGC nanoparticles (yielding RGD-HGC nanoparticles) with a high loading efficiency (>85%). In vitro work demonstrated that RGD-HGC showed prolonged and sustained release of RGD, lasting for 1 week. RGD-HGC also inhibited HUVEC adhesion to a beta ig-h3 protein-coated surface, indicating an antiangiogenic effect of the RGD peptide in the HGC nanoparticles. In an in vivo study, the antiangiogenic peptide drug formulation of RGD-HGC markedly inhibited bFGF-induced angiogenesis and decreased hemoglobin content in Matrigel plugs. Intratumoral administration of RGD-HGC significantly decreased tumor growth and microvessel density compared to native RGD peptide injected either intravenously or intratumorally, because the RGD-HGC formulation strongly enhanced the antiangiogenic and antitumoral efficacy of RGD peptide by affording prolonged and sustained RGD peptide delivery locally and regionally in solid tumors.

Vascular Endothelial Growth Factor Gene Polymorphisms and Risk of Primary Lung Cancer

Angiogenesis is an essential process in the development, growth, and metastasis of malignant tumors including lung cancer. DNA sequence variations in the vascular endothelial growth factor (VEGF) gene may lead to altered VEGF production and/or activity, thereby causing interindividual differences in the susceptibility to lung cancer via their actions on the pathways of tumor angiogenesis. To test this hypothesis, we investigated the potential association between three VEGF polymorphisms (−460T > C, +405C > G, and 936C > T)/haplotypes and the risk of lung cancer in a Korean population. VEGF genotypes were determined in 432 lung cancer patients and 432 healthy controls that were frequency matched for age and sex. VEGF haplotypes were predicted using Bayesian algorithm in the phase program. Compared with the combined +405 CC and CG genotype, the +405 GG genotype found associated with a significantly decreased risk of small cell carcinoma [SCC; adjusted odds ratio (OR), 0.36; 95% confidence interval (95% CI), 0.17-0.78]. The 936 CT genotype and the combined 936 CT and TT genotype were also associated with a significantly decreased risk of SCC compared with the 936 CC genotype (adjusted OR, 0.47; 95% CI, 0.26-0.85 and adjusted OR, 0.44; 95% CI, 0.24-0.80, respectively). Haplotype CGT was associated with a significantly decreased risk of SCC (adjusted OR, 0.39; 95% CI, 0.18-0.87), whereas haplotype TCC conferred a significantly increased risk of SCC (adjusted OR, 1.63; 95% CI, 1.14-2.33). None of the VEGF polymorphisms studied significantly influenced the susceptibility to lung cancer except SCC. However, haplotypes TCT and TGT were significantly associated with the risk of overall lung cancer, respectively (adjusted OR, 0.38; 95% CI, 0.25-0.60 and adjusted OR, 3.94; 95% CI, 2.00-7.76, respectively). These effects of haplotypes TCT and TGT on lung cancer risk were observed in three major histologic types of lung cancer. These results suggest that the VEGF gene may be contribute to an inherited predisposition to lung cancer.

-93G→A polymorphism of hMLH1 and risk of primary lung cancer

Polymorphisms in DNA repair genes may be associated with differences in the repair capacity of DNA damage and may thereby influence an individuals susceptibility to smoking‐related cancer. We investigated the association between the −93G→A polymorphism in the hMLH1 gene and the risk of lung cancer in a Korean population. The hMLH1 −93G→A polymorphism was typed in 372 lung cancer patients and 371 healthy controls that were frequency‐matched for age and sex. There was no significant association between the hMLH1 −93G→A genotype and the risk for adenocarcinoma or small cell carcinoma. However, the AA genotype was associated with a significantly increased risk for squamous cell carcinoma compared with both the GG genotype (adjusted OR = 2.02; 95% CI = 1.15–3.55; p = 0.014) and the combined GG and GA genotype (adjusted OR = 1.83; 95% CI = 1.24–2.71; p = 0.003). When the subjects were stratified by smoking exposure, the AA genotype was associated with a significantly increased risk for squamous cell carcinoma in lighter smokers (≤ 39 pack‐years; adjusted OR = 1.95; 95% CI = 1.03–3.66; p = 0.039) compared with the combined GG and GA genotype, whereas there was no significant association in heavier smokers (> 39 pack‐years; adjusted OR = 1.47; 95% CI = 0.82–2.61). These results suggest that the hMLH1 −93G→A polymorphism could be used as a marker of genetic susceptibility to squamous cell carcinoma of the lung.

Polyproline‐type helical‐structured low‐molecular weight heparin (LMWH)‐taurocholate conjugate as a new angiogenesis inhibitor

Although heparin can regulate angiogenesis, tumor growth and metastasis, its clinical application, as well as that of low‐molecular heparin (LMWH), for treating cancer are limited because of heparins anticoagulant activity and risk of hemorrhages. LMWH‐taurocholate conjugates (LHT7), which have low anticoagulant activity, were synthesized. The structural property of LHT was evaluated by circular dichroism and the binding affinity of LHT7 to vascular endothelial growth factor 165 (VEGF165) was measured by isothermal titration calorimetry. The inhibitory effect of LHT7 on VEGF‐mediated KDR (VEGF‐receptor 2) phosphorylation in Human umbilical vein endothelial cells was evaluated. The VEGF165 dependent Matrigel plug assay was performed to verify the antiangiogenic potential of LHT7 on a VEGF165 inhibitor. Finally, tumor growth inhibition effects of LHT7 on SCC7 and the survival rate of animal models were investigated. Moreover, MDA‐MB231 xenograft mouse model was additionally used to confirm the therapeutic effect of LHT7 on human breast cancer cell line. As a result, LHT7 which has 12.7% of anticoagulant activity of the original LMWH showed a peculiar polyproline‐type helical structure. LHT7 binds to VEGF strongly and inhibits VEGF dependent KDR phosphorylation. The results of Matrigel plug assay proved LHT7 as a strong antiangiogenic agent inhibiting VEGF165. Remarkably, LHT7 showed a significant tumor growth inhibition potential on SCC7 with an increased survival rate. LHT7 also delayed tumor growth in MDA‐MB231 human breast cancer cell lines.

Antiangiogenic and Apoptotic Properties of a Novel Amphiphilic Folate-Heparin-Lithocholate Derivative Having Cellular Internality for Cancer Therapy

PurposeAnitangiogenic and apoptotic properties of a novel chemically modified heparin derivative with low anticoagulant activity were evaluated on the experimental in vitro and in vivo model.Materials and MethodsHeparin-lithocholate conjugate (HL) was initially synthesized by covalently bonding lithocholate to heparin. Folate-HL conjugate (FHL) was further synthesized by conjugating folate to HL. Antiangiogenic and apoptotic abilities of HL and FHL were characterized in vitro and in vivo experimentations.ResultsCompared to unmodified heparin, both HL and FHL represented a low anticoagulant activity (38 and 28%, respectively). HL and FHL maintained antiangiogenic activity even further modification from the results of Matrigel plugs assay. FHL specifically induced apoptosis on KB cells having highly expressed folate receptor after cellular internalization. Both administered HL and FHL had similar antiangiogenic activity and inhibitory effect on tumor growth in vivo although FHL induced higher apoptosis on tumor tissues.ConclusionsIn vivo tumor growth inhibition was possibly due to the decrease of vessel density and apoptotic cell death, although antiangiogenic effect of FHL seemed more actively affected on growth inhibition than apoptotic potential in vivo system. Thus, Low anticoagulant FHL having antiangiogenic and apoptotic properties would provide benefits for the development of a new class of anticancer agent.

Antimetastatic Effect of an Orally Active Heparin Derivative on Experimentally Induced Metastasis

Purpose: Orally active anticancer drugs have great advantages for the treatment of cancer. Compelling data suggest that heparin exhibits critical antimetastatic effects via interference with P-selectin–mediated cell-cell binding. However, heparin should be given parenterally because it is not orally absorbed. Here, we evaluated the inhibitory effect of orally absorbable heparin derivative (LHD) on experimentally induced metastasis. Experimental Design: We developed LHD, which is a chemical conjugate of low molecular weight heparin and deoxycholic acid, and measured the plasma concentration of LHD after oral administration. To evaluate the antimetastatic effect of LHD, we carried out experimental lung metastasis assays in vivo using murine melanoma or human lung carcinoma cells and interruption assay between murine melanoma cells and activated platelets and human umbilical vascular endothelial cells in vitro. Results: In mice, the plasma concentration was ∼7 μg/mL at 20 minutes after oral administration of LHD (10 mg/kg), indicating that bleeding was not induced at this dose. Interestingly, we found that LHD dramatically attenuated metastasis experimentally induced by murine melanoma or human lung carcinoma cells and that its antimetastatic activity was attributed to the interruption of the interactions between melanoma cells and activated platelets and between melanoma cells and human umbilical vascular endothelial cells by blocking selectin-mediated interactions. Furthermore, it prevented tumor growth in secondary organs. Conclusions: On the basis of these findings, the present study shows the possibility of LHD as a suitable first-line anticancer drug that can be used for preventing metastasis and recurrence because it has therapeutic potential as an antimetastatic drug, has lower side effects, and can be orally absorbed.

Facilitated intracellular delivery of peptide-guided nanoparticles in tumor tissues

Macromolecular nanoparticles can extravasate and accumulate within tumor tissues via the passive targeting system, reflecting enhanced permeability and the retention effect. However, the unsatisfactory tumor therapeutic efficacy of the passive-targeting system, attributable to the retention of extravasated nanoparticles in the vicinity of tumor vessels, argues that a new system that facilitates intracellular delivery of nanoparticles within tumors is needed. Here, we developed hydrophobically modified glycol chitosan (HGC) nanoparticles conjugated with interleukin-4 receptor (IL-4R) binding peptides, termed I4R, and tested them in mice bearing IL-4R-positive tumors. These HGC-I4R nanoparticles exhibited enhanced IL-4R-dependent cellular uptake in tumors compared to nonconjugated nanoparticles, leading to better therapeutic and imaging efficacy. We conclude that I4R facilitates and enhances cellular uptake of nanoparticles in tumor tissues. This study suggests that the intracelluar uptake of nanoparticles in tumors is an essential factor to consider in designing nanoparticles for tumor-targeted drug delivery and imaging.