Enhanced Antitumor Efficacy of PhAc-ALGP-Dox, an Enzyme-Activated Doxorubicin Prodrug, in a Panel of THOP1-Expressing Patient-Derived Xenografts of Soft Tissue Sarcoma.

Despite poor response rates and dose-limiting cardiotoxicity, doxorubicin (doxo) remains the standard-of-care for patients with advanced soft tissue sarcoma. We evaluated the efficacy of two tetrapeptidic doxo prodrugs (PhAc-ALGP-Dox or CBR-049 and CBR-050) that are locally activated by enzymes expressed in the tumor environment, in ten sarcoma patient-derived xenografts. Xenograft models were selected based on expression of the main activating enzyme, i.e., thimet oligopeptidase (THOP1). Mice were either randomized to vehicle, doxo, CBR-049 and CBR-050 or control, doxo, aldoxorubicin (aldoxo) and CBR-049. Treatment efficacy was assessed by tumor volume measurement and histological assessment of ex-mouse tumors. CBR-049 showed significant tumor growth delay compared to control in all xenografts investigated and was superior compared to doxo in all but one. At the same time, CBR-049 showed comparable efficacy to aldoxo but the latter was found to have a complex safety profile in mice. CBR-050 demonstrated tumor growth delay compared to control in one xenograft but was not superior to doxo. For both experimental prodrugs, strong immunostaining for THOP1 was found to predict better antitumor efficacy. The prodrugs were well tolerated without any adverse events, even though molar doses were 17-fold higher than those administered and tolerated for doxo.

Encapsulation of doxorubicin prodrug in heat-triggered liposomes overcomes off-target activation for advanced prostate cancer therapy.

L-377,202 prodrug consists of doxorubicin (Dox) conjugated to a prostate-specific antigen (PSA) peptide substrate that can be cleaved by enzymatically active PSA at the tumor site. Despite the initial promise in phase I trial, further testing of L-377,202 (herein called Dox-PSA) was ceased due to some degree of non-specific activation and toxicity concerns. To improve safety of Dox-PSA, we encapsulated it into low temperature-sensitive liposomes (LTSL) to bypass systemic activation, while maintaining its biological activity upon controlled release in response to mild hyperthermia (HT). A time-dependent accumulation of activated prodrug in the nuclei of PSA-expressing cells exposed to mild HT was observed, showing that Dox-PSA was efficiently released from the LTSL, cleaved by PSA and entering the cell nucleus as free Dox. Furthermore, we have shown that Dox-PSA loading in LTSL can block its biological activity at 37°C, while the combination with mild HT resulted in augmented cytotoxicity in both 2D and 3D PC models compared to the free Dox-PSA. More importantly, Dox-PSA encapsulation in LTSL prolonged its blood circulation and reduced Dox accumulation in the heart of C4-2B tumor-bearing mice over the free Dox-PSA, thus significantly improving Dox-PSA therapeutic window. Finally, Dox-PSA-loaded LTSL combined with HT significantly delayed tumor growth at a similar rate as mice treated with free Dox-PSA in both solid and metastatic PC tumor models. This indicates this strategy could block the systemic cleavage of Dox-PSA without reducing its efficacy in vivo, which could represent a safer option to treat patients with locally advanced PC. STATEMENT OF SIGNIFICANCE: This study investigates a new tactic to tackle non-specific cleavage of doxorubicin PSA-activatable prodrug (L-377,202) to treat advanced prostate cancer. In the present study, we report a nanoparticle-based approach to overcome the non-specific activation of L-377,202 in the systemic circulation. This includes encapsulating Dox-PSA in low temperature-sensitive liposomes to prevent its premature hydrolysis and non-specific cleavage. This class of liposomes offers payload protection against degradation in plasma, improved pharmacokinetics and tumor targeting, and an efficient and controlled drug release triggered by mild hyperthermia (HT) (∼42°C). We believe that this strategy holds great promise in bypassing any systemic toxicity concerns that could arise from the premature activation of the prodrug whilst simultaneously being able to control the spatiotemporal context of Dox-PSA cleavage and metabolism.

The safe and effective intraperitoneal chemotherapy with cathepsin B-specific doxorubicin prodrug nanoparticles in ovarian cancer with peritoneal carcinomatosis.

Intraperitoneal (IP) chemotherapy has shown promising efficacy in ovarian cancer with peritoneal carcinomatosis (PC), but in vivo rapid clearance and severe toxicity of free anticancer drugs hinder the effective treatment. Herein, we propose the safe and effective IP chemotherapy with cathepsin B-specific doxorubicin prodrug nanoparticles (PNPs) in ovarian cancer with PC. The PNPs are prepared by self-assembling cathepsin B-specific cleavable peptide (FRRG) and doxorubicin (DOX) conjugates, which are further formulated with pluronic F68. The PNPs exhibit stable spherical structure and cytotoxic DOX is specifically released from PNPs via sequential enzymatic degradation by cathepsin B and intracellular proteases. The PNPs induce cytotoxicity in cathepsin B-overexpressing ovarian (SKOV-3 and HeyA8) and colon (MC38 and CT26) cancer cells, but not in cathepsin B-deficient normal cells in cultured condition. With enhanced cancer-specificity and in vivo residence time, IP injected PNPs efficiently accumulate within PC through two targeting mechanisms of direct penetration (circulation independent) and systemic blood vessel-associated accumulation (circulation dependent). As a result, IP chemotherapy with PNPs efficiently inhibit tumor progression with minimal side effects in peritoneal human ovarian tumor-bearing xenograft (POX) and patient derived xenograft (PDX) models. These results demonstrate that PNPs effectively inhibit progression of ovarian cancer with peritoneal carcinomatosis with minimal local and systemic toxicities by high cancer-specificity and favorable in vivo PK/PD profiles enhancing PC accumulation.

Remote loading paclitaxel-doxorubicin prodrug into liposomes for cancer combination therapy.

The combination of paclitaxel (PTX) and doxorubicin (DOX) has been widely used in the clinic. However, it remains unsatisfied due to the generation of severe toxicity. Previously, we have successfully synthesized a prodrug PTX-S-DOX (PSD). The prodrug displayed comparable in vitro cytotoxicity compared with the mixture of free PTX and DOX. Thus, we speculated that it could be promising to improve the anti-cancer effect and reduce adverse effects by improving the pharmacokinetics behavior of PSD and enhancing tumor accumulation. Due to the fact that copper ions (Cu2+) could coordinate with the anthracene nucleus of DOX, we speculate that the prodrug PSD could be actively loaded into liposomes by Cu2+ gradient. Hence, we designed a remote loading liposomal formulation of PSD (PSD LPs) for combination chemotherapy. The prepared PSD LPs displayed extended blood circulation, improved tumor accumulation, and more significant anti-tumor efficacy compared with PSD NPs. Furthermore, PSD LPs exhibited reduced cardiotoxicity and kidney damage compared with the physical mixture of Taxol and Doxil, indicating better safety. Therefore, this novel nano-platform provides a strategy to deliver doxorubicin with other poorly soluble antineoplastic drugs for combination therapy with high efficacy and low toxicity.

Epidermal growth factor (EGF)-based activatable probe for predicting therapeutic outcome of an EGF-based doxorubicin prodrug.

One of the most promising approaches for the treatment of colorectal cancer is targeting epidermal growth factor receptor (EGFR). Comprehensive research has led to significant clinical outcomes using EGFR-targeted anticancer drugs; however, the response to these drugs still largely varies among individuals. The current diagnostic platform provides limited information that does not enable successful prediction of the anticancer performance of EGFR-targeted drugs. Here, we developed a EGFR-targeted activatable probe for predicting therapeutic efficacy of EGFR-targeted doxorubicin prodrug in colorectal cancer therapy. The EGF-conjugated fluorescence-activatable probe (EGF-probe) and EGF-conjugated doxorubicin prodrug (EGF-prodrug) were both fabricated using peptide substrates that can be dissociated by lysosomal enzymes, and thus share an intracellular mechanism of action. We demonstrated that after EGFR-mediated endocytosis, lysosomal enzymes de-quench the fluorescence of EGF-probe and activate the cytotoxicity of EGF-prodrug. When evaluated in vivo, EGF-probe yielded an outstanding cancer-specific imaging ability with reduced background signals. EGF-prodrug also successfully targeted the tumor and promoted cancer cell death. We tested different colorectal cancer cell types to investigate the correlation between the fluorescence recovery efficiency of EGF-probe and the cytotoxicity of EGF-prodrug. Strong correlations were observed both in vitro and in vivo. The actions of EGF-probe and EGF-prodrug were dependent on the inherent lysosomal activity of the cell type rather than its EGFR expression level. Our proposed approach using EGF-probe and EGF-prodrug may overcome the major drawback of the conventional theranostic platform and provide great opportunity for successful personalized cancer therapy.

Combretastatin A4 Nanodrug-Induced MMP9 Amplification Boosts Tumor-Selective Release of Doxorubicin Prodrug.

Tumor-associated enzyme-activated prodrugs can potentially improve the selectivity of chemotherapeutics. However, the paucity of tumor-associated enzymes which are essential for prodrug activation usually limits the antitumor potency. A cooperative strategy that utilizes combretastatin A4 nanodrug (CA4-NPs) and matrix metalloproteinase 9 (MMP9)-activated doxorubicin prodrug (MMP9-DOX-NPs) is developed. CA4 is a typical vascular disrupting agent that can selectively disrupt immature tumor blood vessels and exacerbate the tumor hypoxia state. After treatment with CA4-NPs, MMP9 expression can be significantly enhanced by 5.6-fold in treated tumors, which further boosts tumor-selective active drug release of MMP9-DOX-NPs by 3.7-fold in an orthotopic 4T1 mammary adenocarcinoma mouse model. The sequential delivery of CA4-NPs and MMP9-DOX-NPs exhibits enhanced antitumor efficacy with reduced systemic toxicity compared with the noncooperative controls.

Low density lipoprotein-inspired nanostructured lipid nanoparticles containing pro-doxorubicin to enhance tumor-targeted therapeutic efficiency.

Inefficient tumor accumulation and controlling drug release at the tumor site are two major obstacles limiting the antitumor efficacy of nanoparticle delivery systems. Inspired by the biological structure and function of low-density lipoprotein (LDL), a pH-sensitive ApoB-100/Oleic acid-DOX/NLC (AODN) nanoparticle based on nanostructured lipid carrier (NLC) was prepared in this study. The biological composition of ApoB-containing NLC nanoparticles is similar to that of LDL, which can effectively increase the cycle time and targeting efficiency of nanoparticles. Meantime, the doxorubicin prodrug strategy was used to increase the drug loading of the nanoparticles and achieve drug-sensitive release. In vitro results indicated that AODN nanoparticles can cause more drugs to be phagocytosed by LDL receptor-mediated endocytosis, thus showing high cytotoxicity in 4T1 cells. In vivo experiments have shown that pH-sensitive AODN nanoparticles can cause more drugs to accumulate in the tumor site, reducing systemic toxicity and effectively inhibiting orthotopic breast cancer. These data provide strong evidence that the strategy of combining bionics and prodrug technology provides a new approach to improving the efficiency of chemotherapy drugs in cancer treatment. STATEMENT OF SIGNIFICANCE: Inefficient tumor accumulation and controlling drug release at the tumor site are two major obstacles limiting the antitumor efficacy of nanoparticle delivery systems. Inspired by low density lipoprotein, a pH-sensitive ApoB-100/oleic acid-DOX/NLC (AODN) nanoparticle based on nanostructured lipid carrier (NLC) was prepared. Its biological composition is similar to that of LDL, which can effectively increase the cycle time and targeting efficiency of drugs. Then, the doxorubicin prodrug strategy was used to increase the drug loading of the nanoparticles and achieve drug-sensitive release. AODN nanoparticles can effectively inhibit tumor by effectively accumulating at tumor site and controlling release. The strategy of combining bionics and prodrug technology provides a new approach to improving the efficiency of chemotherapy drugs in cancer treatment.

Lectin-Mediated pH-Sensitive Doxorubicin Prodrug for Pre-Targeted Chemotherapy of Colorectal Cancer with Enhanced Efficacy and Reduced Side Effects.

Doxorubicin (DOX) has been clinically used as a broad-spectrum chemotherapeutic agent for decades, but its clinical application is hindered by the lack of tumour specificity, severe cardiotoxicity and haematotoxicity. Pre-targeted strategies are highly tumour-specific, therapeutic approaches. Herein, a novel pre-targeted system was constructed, aiming to enhance anticancer efficacy of DOX and maximally reduce its side effects. Methods: The DOX prodrug (bDOX) was first synthesized by conjugating DOX with mini-PEGylated (mPEGylated) biotin through a pH-sensitive bond. During the pre-targeted treatment, avidin was first administrated. After an optimized interval, bDOX was second administrated. The nontoxic prodrug bDOX was eventually transformed into the toxic anticancer form (DOX) by a pH-triggered cleavage specifically in tumour cells. The drug efficacy and side effect of the two-step, pre-targeted treatment were fully compared with free DOX in vitro and in vivo. Results: The prodrug bDOX was quite stable under neutral conditions and nearly nontoxic, but was immediately transformed into the toxic anticancer form (DOX) under acidic conditions. Compared to free DOX, the pre-targeted bDOX exhibited a higher cellular uptake by human colorectal tumour cells (LS180 and HT-29 cells). In vivo evaluation performed on LS180 xenograft animal model demonstrated that the pre-targeted bDOX achieved a much more significant tumour inhibition than free DOX. The largely decreased, unwanted bystander toxicity was demonstrated by changes in body weight, cardiomyocyte apoptosis, blood routine examination and splenic pathological changes. Conclusion: The high therapeutic efficacy, together with the minimal side effects, of this easily synthesized, pre-targeted system exhibited immense potentiality for the clinical application of DOX delivery.

Intracellular Activation of a Prostate Specific Antigen-Cleavable Doxorubicin Prodrug: A Key Feature Toward Prodrug-Nanomedicine Design.

L-377,202 prodrug (Dox-PSA) was in phase I clinical trials for patients with metastatic castration-resistant prostate cancer (mCRPC). It consists of doxorubicin (Dox) conjugated to a prostate specific antigen (PSA)-cleavable peptide that can be selectively activated by secreted PSA at the tumor site. However, despite the initial promising results, further clinical testing with Dox-PSA was halted due to toxicity concerns emerging from non-PSA-specific cleavage, following systemic administration. In the present study, we have reported, for the first time, the intracellular activation of Dox-PSA, where Dox nuclear uptake was specific to C4-2B (PSA-expressing) cells, which agreed with the cytotoxicity studies. This finding was confirmed by encapsulating Dox-PSA prodrug into pH-sensitive liposomes to enable prodrug intracellular release, followed by its enzymatic activation. Interestingly, our results demonstrated that Dox-PSA loaded into pH-responsive nanoparticles exhibited cytotoxicity comparable to free prodrug in C4-2B monolayers, with superior activity in tumor spheroids, due to deeper penetration within tumor spheroids. Our approach could open the doors for novel Dox-PSA nanomedicines with higher safety and efficacy to treat advanced and metastatic prostate cancer.

Enhancing the Efficacy and Safety of Doxorubicin against Hepatocellular Carcinoma through a Modular Assembly Approach: The Combination of Polymeric Prodrug Design, Nanoparticle Encapsulation, and Cancer Cell-Specific Drug Targeting.

Intervention is urgently required to improve the therapeutic outcome for patients with unresectable hepatocellular carcinomas (HCCs). However, current chemotherapeutics, such as sorafenib and doxorubicin (DOX), provide only limited therapeutic benefits for this devastating disease. In this context, we present a modular assembly approach to the construction of a systemically injectable nanotherapeutic that can efficiently and safely deliver DOX in vivo. To achieve this goal, we covalently attached DOX to a polylactide (PLA) building block (Mw = 2800, n = 36), yielding DOX-PLA conjugate 1. Due to the lipophilicity imparted by PLA, the conjugate 1 coassembled with an amphiphilic lipid, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol) 2000] (DSPE-PEG2000), to form nanoparticles (NPs). To achieve preferential tumor accumulation, we additionally decorated the particle surface with an HCC-specific peptide moiety (i.e., SP94). The resulting HCC-targetable DOX-encapsulating NPs (termed tNP-PLA-DOX) exhibited several unique characteristics, including the feasible fabrication of sub-100 nm NPs, substantially delayed drug release profiles of several weeks, HCC cell-specific uptake and tumor accumulation in an in vivo mouse model, as well as alleviated drug toxicity in animals. Collectively, these results show that the integration of multiple components within a single nanocarrier via modular assembly is cost-effective for the creation of safe anticancer nanotherapeutics. The presented DOX-based nanomedicines have potential for enhancing the therapeutic index in patients.

A Novel Doxorubicin Prodrug with GRP78 Recognition and Nucleus-Targeting Ability for Safe and Effective Cancer Therapy.

Glucose-regulated protein of 78 kDa (GRP78) has become an attractive and novel target for tumor therapy. Design and construction of powerful delivery systems that could efficiently transport doxorubicin (DOX) to a tumor-cell nucleus remains a formidable challenge for improving the tumor therapeutic index and mitigating side effects to normal tissues. Herein, a novel doxorubicin prodrug (NDP) with GRP78 recognition and nucleus-targeting ability was synthesized by a facile chemical route. NDP exhibited an enhanced antiproliferative activity against colorectal cancer cells and could efficiently enter the cell nucleus. Furthermore, it is inspiring to note that NDP displayed a much stronger inhibitory efficacy against the growth of colorectal cancer xenografts in nude mice than free DOX and showed superior in vivo safety. Together, the work provides a novel GRP78 and nucleus-targeting strategy, and the NDP holds great promise to be used as a potent and safe chemotherapeutic agent.

A UPLC-MS/MS method for quantification of a novel doxorubicin conjugation prodrug in tumor cells / 药学学报

In this study, we developed a rapid and sensitive ultra high-performance liquid chromatographytandem mass spectrometry (UPLC-MS/MS) method to detect a sulfide bond doxorubicin conjugation prodrug (DOX-S-DOX) in human breast cancer tumor cells (MCF-7). The samples were prepared by acetonitrile precipitation using daunorubicin as internal standard (IS). A reversed phase C18 analytical column (Agilent Eclipse plus C18 RRHD 1.8 μm, 2.1 mm×50 mm) was utilized to separate the samples under gradient elution conditions. Mobile phase was a mixture of 0.1% formic acid in water and methanol at a flow rate of 0.4 mL ·min-1. The analysis was conducted on the mass spectrometer using an electrospray interface (ESI) in the positive ionization model. The calibration range was 20.0-400 ng·mL-1 with the correlation coefficients (r2) ≥ 0.99. The inter-and intra-assay precision (relative standard deviation, RSD%) of quality control samples was within 3.77%-8.35% and relative error (RE%) for accuracy was between -2.04% and 2.62%. Recovery (97.67%-104.2%) and matrix effect (104.8%-113.9%) were consistent, precise, and reproducible at different quality control levels in accordance with FDA guidance. The assay was successfully used in the cellular pharmacokinetics study of DOX-S-DOX, which may provide a clue to explore analytical methods of other prodrug forms of DOX.

A sensitive liquid chromatography/electrospray tandem mass spectroscopy method for simultaneous quantification of a disulfide bond doxorubicin conjugation prodrug and activated doxorubicin: Application to cellular pharmacokinetic and catabolism studies.

In recent years, drug conjugates as a prodrug strategy have been widely studied, especially combined with nanotechnology. Disulfide-linked doxorubicin drug-drug conjugate (DOX-S-S-DOX) nanoparticles, have recently been developed as a doxorubicin prodrug nanoparticles with greater anticancer activity and less toxicity than doxorubicin in vivo, while its intracellular kinetics and metabolism is unclear which may provide us with a deeper understanding of its pharmacological mechanism and antitumor effect. Hence, in this study, a rapid and sensitive ultra high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to detect doxorubicin (DOX) activated from DOX-S-S-DOX, as well as the prodrug itself in human breast cancer tumor cells (MCF-7). Sample preparation involved acetonitrile precipitation to extract the analytes simultaneously and bath sonication to remove intercalated DOX from DNA. The calibration range was 3-60ng/mL for DOX and 20-400ng/mL for DOX-S-S-DOX with the correlation coefficients (r2)≥0.99, using daunorubicin as internal standard (IS). The inter- and intra-assay precision (relative standard deviation, RSD%) of quality control samples was in the acceptable range (<15%) and relative error (RE%) for accuracy was between -5.35 and 9.18% for all analytes. Recovery (59.28-69.53% for DOX-S-S-DOX and 99.13-100.10% for DOX) and matrix effect (99.69-111.19%) was consistent, precise, and reproducible at different quality control levels in accordance with FDA guidance. Stability studies showed that DOX-S-S-DOX was unstable both during the bench-top and long-term storage, while the stability during sample preparation and LC-MS runtime was suitable for all the analytes. Hence, the samples should be prepared as soon as possible at the time point to prevent the catabolism of DOX-S-S-DOX. The assay was successfully used in the cellular metabolism and pharmacokinetics study of DOX-S-S-DOX and it may give a clue to explore analytical methods of other prodrug forms of DOX.

Dual-targeted and pH-sensitive Doxorubicin Prodrug-Microbubble Complex with Ultrasound for Tumor Treatment.

In this study, we investigated the potential of a dual-targeted pH-sensitive doxorubicin prodrug-microbubble complex (DPMC) in ultrasound (US)-assisted antitumor therapy. The doxorubicin prodrug (DP) consists of a succinylated-heparin carrier conjugated with doxorubicin (DOX) via hydrazone linkage and decorated with dual targeting ligands, folate and cRGD peptide. Combination of microbubble (MB) and DP, generated via avidin-biotin binding, promoted intracellular accumulation and improved therapeutic efficiency assisted by US cavitation and sonoporation. Aggregates of prepared DP were observed with an inhomogeneous size distribution (average diameters: 149.6±29.8 nm and 1036.2±38.8 nm, PDI: 1.0) while DPMC exhibited a uniform distribution (average diameter: 5.804±2.1 µm), facilitating its usage for drug delivery. Notably, upon US exposure, DPMC was disrupted and aggregated DP dispersed into homogeneous small-sized nanoparticles (average diameter: 128.6±42.3 nm, PDI: 0.21). DPMC could target to angiogenic endothelial cells in tumor region via αvß3-mediated recognition and subsequently facilitate its specific binding to tumor cells mediated via recognition of folate receptor (FR) after US exposure. In vitro experiments showed higher tumor specificity and killing ability of DPMC with US than free DOX and DP for breast cancer MCF-7 cells. Furthermore, significant accumulation and specificity for tumor tissues of DPMC with US were detected using in vivo fluorescence and ultrasound molecular imaging, indicating its potential to integrate tumor imaging and therapy. In particular, through inducing apoptosis, inhibiting cell proliferation and antagonizing angiogenesis, DPMC with US produced higher tumor inhibition rates than DOX or DPMC without US in MCF-7 xenograft tumor-bearing mice while inducing no obvious body weight loss. Our strategy provides an effective platform for the delivery of large-sized or aggregated particles to tumor sites, thereby extending their therapeutic applications in vivo.

Simultaneous delivery of anti-miR21 with doxorubicin prodrug by mimetic lipoprotein nanoparticles for synergistic effect against drug resistance in cancer cells.

The development of drug resistance in cancer cells is one of the major obstacles to achieving effective chemotherapy. We hypothesized that the combination of a doxorubicin (Dox) prodrug and microRNA (miR)21 inhibitor might show synergistic antitumor effects on drug-resistant breast cancer cells. In this study, we aimed to develop new high-density lipoprotein-mimicking nanoparticles (HMNs) for coencapsulation and codelivery of this potential combination. Dox was coupled with a nuclear localization signal (NLS) peptide to construct a prodrug (NLS-Dox), thereby electrostatically condensing miR21 inhibitor (anti-miR21) to form cationic complexes. The HMNs were formulated by shielding these complexes with anionic lipids and Apo AI proteins. We have characterized that the coloaded HMNs had uniformly dispersed distribution, favorable negatively charged surface, and high coencapsulation efficiency. The HMN formulation effectively codelivered NLS-Dox and anti-miR21 into Dox-resistant breast cancer MCF7/ADR cells and wild-type MCF7 cells via a high-density-lipoprotein receptor-mediated pathway, which facilitated the escape of Pgp drug efflux. The coloaded HMNs consisting of NLS-Dox/anti-miR21 demonstrated greater cytotoxicity with enhanced intracellular accumulation in resistant MCF7/ADR cells compared with free Dox solution. The reversal of drug resistance by coloaded HMNs might be attributed to the suppression of miR21 expression and the related antiapoptosis network. Furthermore, the codelivery of anti-miR21 and NLS-Dox by HMNs showed synergistic antiproliferative effects in MCF7/ADR-bearing nude mice, and was more effective in tumor inhibition than other drug formulations. These data suggested that codelivery of anti-miR21 and chemotherapeutic agents by HMNs might be a promising strategy for antitumor therapy, and could restore the drug sensitivity of cancer cells, alter intracellular drug distribution, and ultimately enhance chemotherapeutic effects.

Doxorubicin/heparin composite nanoparticles for caspase-activated prodrug chemotherapy.

Caspase-activated prodrug chemotherapy is introduced and demonstrated using the composite nanoparticles (NPs), which deliver doxorubicin (DOX) and DEVD-S-DOX together to the tumor tissue. DEVD-S-DOX, DOX linked to a peptide moiety (DEVD), is a prodrug that is cleaved into free DOX by caspase-3 upon apoptosis. DEVD-S-DOX has no therapeutic efficacy, but it changes into free DOX with the expression of caspase-3. With the accumulation of the composite NPs in the tumor tissue by the enhanced permeation and retention (EPR) effect, a small exposure of DOX in the tumor cells initiated apoptosis in a localized area of the tumor tissue, which induced caspase-3 activation. Cleavage of DEVD-S-DOX into free DOX by caspase-3 continued with repetitive activation of caspase-3 and cleavage of DEVD-S-DOX at the tumor site. The composite NPs were characterized with transmittance electron microscopy (TEM) and particle size analyzer. We then evaluated the nanoparticle drug release, therapeutic efficacy, and in vivo biodistribution for tumor targeting using a non-invasive live animal imaging technology and the quantification of DOX with high performance liquid chromatography. DOX-induced apoptosis-targeted chemotherapy (DIATC) was verified by in vitro/in vivo DEVD-S-DOX response to free DOX and cellular uptake behavior of the composite NPs with flow cytometry analysis. Significant antitumor efficacy with minimal cardiotoxicity was also observed, which supported DIATC for improved chemotherapy.

Synthesis of acid-sensitive doxorubicin prodrug nanoparticle and its application in brain glioma treatment / 天津医药

Objective To synthesize a new kind of acid-sensitive doxorubicin prodrug nanoparticles and to evaluate its anti-brain glioma effect and efficiency through blood-brain barrier (BBB). Methods The prodrug acid-sensitive poly-ethylene glycol (PEG)-doxorubicin (PEG-DOX) copolymer was synthesized by Schiff base reaction, and PEG-DOX pro-drug nanoparticles (PEG-DOX NPs) were prepared by self-assembling. The character of PEG-DOX copolymer was detected by dynamic light scattering (DLS) instrument and 1H NMR. The morphology of PEG-DOX NPs was observed by transmission electron microscopy (TEM). The character of drug release was detected by UV mothed. The cellular uptake efficiency of glio-ma cells to PEG-DOX NPs was observed by inverted fluorescence microscope. The anti-brain glioma effects of PEG-DOX NPs and Free DOX were studied by MTT mothed. PS80-PEG-DOX NPs were gained by the modification of PEG-DOX NPs with Tween 80. Nine BALB/c mice were separated into Free DOX, PEG-DOX NPs and PS80-PEG-DOX NPs groups by ran-dom drawing lots. The mean fluorescence intensity of brain and main organs were observed by in vivo imaging system. Re-sults The copolymer of PEG-DOX can self-assemble into nanoparticles with the diameter of 100 nm. PEG-DOX NPs can quickly release DOX in acid environment. Although PEG-DOX NPs had slow cancer cell uptake than Free DOX, it had lon-ger accumulation. MTT results showed that PEG-DOX NPs had concentration dependent anti-brain glioma effect. Indepen-dent samples t-test indicated that the efficiency through BBB was significantly higher in PS80-PEG-DOX NPs group than that of Free DOX group and PEG-DOX NPs group. Conclusion PEG-DOX NPs show well anti-brain glioma effect in vi-tro, and can across BBB with high efficiency after modification, which make it possible for a potential therapeutic prodrug for brain glioma.