A fast tumor-targeting near-infrared fluorescent probe based on bombesin analog for in vivo tumor imaging.

Bombesin (BBN), an analog of gastrin-releasing peptide (GRP), of which the receptors are over-expressed on various tumor cells, is able to bind to GRP receptor specifically. In this study, a near-infrared fluorescent dye (MPA) and polyethylene glycol (PEG) were conjugated to BBN analog to form BBN[7-14]-MPA and BBN[7-14]-SA-PEG-MPA. The successful synthesis of the two probes was proved by the characterization via sodium dodecylsulfate-polyacrylamide gel electrophoresis, infrared and optical spectra. Cellular uptakes studies indicated that BBN-based probes were mediated by gastrin-releasing peptide receptors (GRPR) on tumor cells and the PEG modified probe had higher affinity. The dynamic distribution and clearance investigations showed that the BBN-based probes were eliminated by the liver-kidney pathway. Furthermore, both of the BBN-based probes displayed tumor-targeting ability in GRPR over-expressed tumor-bearing mice. The PEG modified probe exhibited faster and higher tumor targeting capability than BBN[7-14]-MPA. The results implied that BBN[7-14]-SA-PEG-MPA could act as an effective fluorescence probe for tumor imaging.

Targeted cancer therapy with a 2-deoxyglucose-based adriamycin complex.

Adriamycin (ADM) has been effective against many types of solid tumors in clinical applications. However, its use is limited because of systemic toxicities, primarily cardiotoxicity, and multidrug resistance. In this study, a new active receptor-mediated complex, ADM conjugated with 2-amino-2-deoxy-d-glucose and succinic acid (2DG-SUC-ADM), was designed to target tumor cells through glucose transporter 1 (GLUT1). MTT assay and confocal images showed that the complex had better inhibition rate to tumor cells and low toxicity to normal cells. Most importantly, the complex displayed a potential to reverse overcome multidrug resistance in cancer cells, with more complex transported into the nucleus of tumor cells. Our in vivo experiments also showed that this new complex could significantly decrease organ toxicity and enhance the antitumor efficacy compared with free ADM, indicating a promising drug of 2DG-SUC-ADM for targeted cancer therapy.

A pH-sensitive doxorubicin prodrug based on folate-conjugated BSA for tumor-targeted drug delivery.

Doxorubicin (DOX) is one of the most effective anti-cancer drugs, but its therapeutic efficacy is greatly hampered by its non-specific delivery to the target tissue and the resultant cumulative cardiotoxicity and nephrotoxicity. In order to overcome this limitation, we prepared a folate-bovine serum albumin (BSA)-cis-aconitic anhydride-doxorubicin prodrug, denoted by FA-BSA-CAD. A tumor-targeting agent, folic acid, was linked to BSA to increase the selective targeting ability of the conjugate. BSA provided a large number of reactive sites for multivalent coupling of bioactive molecules and improved the water-solubility of the prodrug. DOX is attached to the BSA via a pH-sensitive linker, cis-aconitic anhydride, which hydrolyzes in the acidic lysosomal environment to allow pH-responsive release of DOX. The in vitro results demonstrate a pH-responsive drug release under different pH conditions. Furthermore, the targeting ability and therapeutic efficacy of the prodrug were assessed both in vitro and in vivo. The results demonstrate that FA-BSA-CAD prodrug selectively targeted tumor cells and tissue, with associated reduction in non-specific toxicity to the normal cells. More importantly, the therapeutic efficacy of the prodrug for FA-positive tumors increased compared to the non-conjuagted DOX.

Fast clearing RGD-based near-infrared fluorescent probes for in vivo tumor diagnosis.

A fast clearing hydrophilic near-infrared (NIR) dye ICG-Der-02 was used to constitute tumor targeting contrast agents. Cell adhesion molecule integrin α(v)ß(3) served as the target receptor because of its unique expression on almost all sprouting tumor vasculatures. The purpose of this study was to synthesize and compare the properties of integrin α(v)ß(3)-targeted, fast clearing NIR probes both in vitro and in vivo for tumor diagnosis. ICG-Der-02 was covalently conjugated to three kinds of RGD peptide including linear, monoeric cyclic and dimeric RGD to form three RGD-based NIR probes. The integrin receptor specificities of these probes were evaluated in vitro by confocal microscopy. The dynamic bio-distribution and elimination ratse were in vivo real-time monitored by a near-infrared imaging system in normal mice. Further, the in vivo tumor targeting abilities of the RGD-based NIR probes were compared in α(v)ß(3) -positive MDA-MB-231, U87MG and α(v)ß(3)-negtive MCF-7 xenograft mice models. Three RGD-based NIR probes were successfully synthesized with good optical properties. In vitro cellular experiments indicated that the probes have a clear binding affinity to α(υ)ß(3) -positive tumor cells, with a cyclic dimeric RGD probe owing the highest integrin affinity. Dynamic bio-distributions of these probes showed a rapid clearing rate through the renal pathway. In vivo tumor targeting ability of the RGD-based porbes was demonstrated on MDA-MB-231 and U87MG tumor models. As expected, the c(RGDyK)(2)-ICG-Der-02 probe displayed the highest tumor-to-normal tissue contrast. The in vitro and in vivo block experiments confirmed the receptor binding specificity of the probes. The hydrophilic dye-labeled NIR probes exhibited a fast clearing rate and deep tissue penetration capability. Further, the α(υ)ß(3) receptor affinity of the three RGD-based NIR probes followed the order of dimer cyclic > monomer cyclic > linear. The results demonstrate potent fast clearing probes for in vivo early tumor diagnosis.

Synthesis of a novel L-methyl-methionine-ICG-Der-02 fluorescent probe for in vivo near infrared imaging of tumors.

PURPOSE: A novel near infrared fluorescent probe, L-methyl-methionine (Met)-ICG-Der-02, was synthesized and characterized for in vivo imaging of tumors and early diagnosis of cancers. METHOD: Met was conjugated with ICG-Der-02 dye through the amide bond function by ethyl-3-(3-dimethyllaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide catalysis chemistry. Met-ICG-Der-02 probe uptake was evaluated on PC3, MDA-MB-231, and human embryonic lung fibroblast cell lines. The dynamics of Met-ICG-Der-02 was investigated in athymic nude mice prior to evaluation of the probe targeting capability in prostate and breast cancer models. RESULTS: Met-ICG-Der-02 was successfully synthesized. Cell experiments demonstrated excellent cellular uptake of Met-ICG-Der-02 on cancer cell lines without cytotoxicity. Optical imaging showed a distinguishable fluorescence signal in the tumor area at 2 h while maximal tumor-to-normal tissue contrast ratio was at 12 h Met-ICG-Der-02 post-injection. Additionally, dynamic study of the probe indicated intestinal and liver-kidney clearance pathways. CONCLUSION: Met-ICG-Der-02 probe is a promising optical imaging agent for tumor diagnosis, especially in their early stage.

A paclitaxel-conjugated adenovirus vector for targeted drug delivery for tumor therapy.

Tumor-targeted drug delivery is an attractive strategy in cancer treatment. Our previous study demonstrated that modified adenovirus has strong tumor targeting ability and less toxicity to surrounding normal tissue. In this study, Paclitaxel (PTX), a widely used clinical anticancer drug, was conjugated to folate-modified adenovirus (Ad) nanoparticles by using succinic anhydride and Fmoc-Glu(OtBu)-OH linkers to form two prodrugs, FA-Ad-Suc-PTX and FA-Ad-ICG02-Glu-PTX. Near-infrared (NIR) fluorescent dye ICG-Der-02 was attached to -NH(2)-Glu(OtBu)-PTX for in vivo optical imaging. In vitro and acute toxicity study demonstrates the low toxicity of the prodrug FA-Ad-Suc-PTX and FA-Ad-ICG02-Glu-PTX compared to the free drug. The dynamic behaviors and targeting ability of FA-Ad-ICG02-Glu-PTX on MDA-MB-231 tumor-bearing mice were investigated by NIR fluorescence imaging. The result show that PTX-conjugated Ad vector could enhance the targeting and residence time in tumor site. In vitro and in vivo studies demonstrate that Coxsackie adenovirus receptor (CAR) or foliate receptor (FR)-mediated uptake of FA-Ad-loaded PTX induced highly anti-tumor activity. The results support the potential of using chemically modified Ad vector as drug-loaded tumor-targeting delivery system.