Tumor-Specific Delivery and Therapy by Double-Targeted DTX-CMCS-PEG-NGR Conjugates

Advances in Chitosan-based Drug Delivery Systems in Melanoma: A Narrative Review

Melanoma accounts for the minority of skin cancer cases. However, it has the highest mortality rate among the subtypes of skin cancer. At the early stages of the disease, patients show a good prognosis after the surgery, but developing metastases leads to a remarkable drop in patients' 5-year survival rate. Despite the advances made in the therapeutic approaches to this disease, melanoma treatment is still facing several obstacles. Systemic toxicity, water insolubility, instability, lack of proper biodistribution, inadequate cellular penetration, and rapid clearance are some of the challenges that should be addressed in the field of melanoma treatment. While various delivery systems have been developed to circumvent these challenges, chitosan-based delivery platforms have indicated significant success. Chitosan that is produced by the deacetylation of chitin can be formulated into different materials (e.g., nanoparticle, film, and hydrogel) due to its characteristics. Both in vitro and in vivo studies have reported that chitosan-based materials can be used in drug delivery systems while offering a solution for the common problems in this area, such as enhancing biodistribution and skin penetration as well as the sustained release of the drugs. Herein, we reviewed the studies concerning the role of chitosan as a drug delivery system in melanoma and discussed how these drug systems are used for delivering chemotherapeutic drugs (e.g., doxorubicin and paclitaxel), genes (e.g., TRAIL), and RNAs (e.g., miRNA199a and STAT3 siRNA) successfully. Furthermore, we take a look into the role of chitosan-based nanoparticles in neutron capture therapy.

NGR-Based Radiopharmaceuticals for Angiogenesis Imaging: A Preclinical Review

Angiogenesis plays a crucial role in tumour progression and metastatic spread; therefore, the development of specific vectors targeting angiogenesis has attracted the attention of several researchers. Since angiogenesis-associated aminopeptidase N (APN/CD13) is highly expressed on the surface of activated endothelial cells of new blood vessels and a wide range of tumour cells, it holds great promise for imaging and therapy in the field of cancer medicine. The selective binding capability of asparagine-glycine-arginine (NGR) motif containing molecules to APN/CD13 makes radiolabelled NGR peptides promising radiopharmaceuticals for the non-invasive, real-time imaging of APN/CD13 overexpressing malignancies at the molecular level. Preclinical small animal model systems are major keystones for the evaluation of the in vivo imaging behaviour of radiolabelled NGR derivatives. Based on existing literature data, several positron emission tomography (PET) and single-photon emission computed tomography (SPECT) radioisotopes have been applied so far for the labelling of tumour vasculature homing NGR sequences such as Gallium-68 (68Ga), Copper-64 (64Cu), Technetium-99m (99mTc), Lutetium-177 (177Lu), Rhenium-188 (188Re), or Bismuth-213 (213Bi). Herein, a comprehensive overview is provided of the recent preclinical experiences with radiolabelled imaging probes targeting angiogenesis.

Co-delivery of microRNA-150 and quercetin by lipid nanoparticles (LNPs) for the targeted treatment of age-related macular degeneration (AMD)

Age-related macular degeneration (AMD) is characterized by choroidal neovascularization (CNV), which leads to severe vision loss in middle-aged and elderly patients. Current treatments for CNV show weak, transient efficacy, and they can cause several adverse effects. A potential new treatment is to use microRNA-150 (mR150), which regulates physiological and pathological angiogenesis by modulating the expression of CXCR4 at the post-transcriptional level. Here, we developed solid lipid nanoparticles that we modified with an Asp-Gly-Arg peptide to target endothelial cells during abnormal angiogenesis, then we co-loaded them with mR150 and the anti-angiogenic drug quercetin. The resulting nanoparticles had an average size around 200 nm and showed strong ability to target the fundus and inhibit CNV for up to two weeks in a mouse model without causing retinal toxicity. They significantly enhanced the uptake of mR150 in vitro compared to free mR150 or nanoparticles without peptide. Our study suggests that co-administration of mR150 and quercetin has potential for treating age-related macular degeneration and that nanoparticles modified with Asp-Gly-Arg peptide are an effective platform for the co-delivery of small-molecule and nucleic acid drugs via intravitreal injection.

A Review on Drug Delivery System for Tumor Therapy

In recent years, with the development of nanomaterials, the research of drug delivery systems has become a new field of cancer therapy. Compared with conventional antitumor drugs, drug delivery systems such as drug nanoparticles (NPs) are expected to have more advantages in antineoplastic effects, including easy preparation, high efficiency, low toxicity, especially active tumor-targeting ability. Drug delivery systems are usually composed of delivery carriers, antitumor drugs, and even target molecules. At present, there are few comprehensive reports on a summary of drug delivery systems applied for tumor therapy. This review introduces the preparation, characteristics, and applications of several common delivery carriers and expounds the antitumor mechanism of different antitumor drugs in delivery carriers in detail which provides a more theoretical basis for clinical application of personalized cancer nanomedicine in the future.

"Layer peeling" co-delivery system for enhanced RNA interference-based tumor associated macrophages-specific chemoimmunotherapy

RNA interference (RNAi)-based immunotherapy combined with chemotherapy has emerged as a promising therapeutic strategy for cancer treatment. The transport of siRNA and small molecular agents from the tumor vasculature to a separate therapeutic target has been impeded by multiple physiological barriers, which has restricted the development of RNAi-based chemoimmunotherapy. A nanotechnology-based co-delivery system was superior in improving the co-localization of gene and drug in the same tumor cell, while a co-delivery system for chemoimmunotherapy was expected to realize xenotype cell-targeting, which means delivering immunotherapy agents and chemotherapy drugs to immune cells and tumor cells, respectively. A multilayer structure co-delivery system was outstanding in crossing these barriers and targeting different cells in tumor tissue. Herein, a "layer peeling" co-delivery system (CDMPR) was developed with co-loaded IKKβ-siRNA and doxorubicin (DOX), in which IKKβ-siRNA was used for RNAi-based tumor associated macrophages (TAMs) polarization for immunotherapy and DOX was used for chemotherapy. A transwell assay in vitro and an immunofluorescence assay in Hepa1-6 tumor-bearing mice indicated that CDMPR exhibited a pH-sensitive disassembly ability in tumor tissue, IKKβ-siRNA was precisely delivered to M2-type TAMs and DOX was internalized into tumor cells. An M2-type TAMs polarization ability study of CDMPR demonstrated that M2-type TAMs could be polarized to M1-type TAMs by CDMPR in vitro and in vivo. In Hepa1-6 tumor-bearing mice, CDMPR exhibited improved antitumor efficiency with M2-type re-polarization ability by the precise delivery of IKKβ-siRNA and DOX to M2-type TAMs and tumor cells, respectively. Consequently, the combination of RNAi-based TAMs polarization and chemotherapy by the "layer peeling" co-delivery system would achieve an enhanced chemoimmunotherapy effect, which provides a novel strategy to improve cancer therapeutic effects.

Effective treatment of drug-resistant lung cancer via a nanogel capable of reactivating cisplatin and enhancing early apoptosis

Cisplatin resistance is a daunting obstacle in cancer therapy and one of the major causes for treatment failure due to the inadequate drug activity and apoptosis induction. To overcome cisplatin resistance, we proposed a multifunctional nanogel (designated as Valproate-D-Nanogel) capable of reactivating cisplatin and enhancing early apoptosis. This Valproate-D-Nanogel was prepared through copolymerizing carboxymethyl chitosan with diallyl disulfide and subsequent grafting with valproate to reverse the drug-resistance in cisplatin-resistant human lung adenocarcinoma cancer. It can significantly increase the proportion of G2/M phase (up to 3.2-fold enhancement) to reactivate cisplatin via high level of G2/M arrest induced by valproate. Meanwhile, the intracellular ROS-P53 crosstalk can be upregulated by diallyl disulfide (up to 8-fold increase of ROS) and valproate (up to 18-fold increase of P53) to enhance early apoptosis. The synchronization of enhanced G2/M arrest and ROS-P53 crosstalk devotes to reverse the cisplatin resistance with a high level of resistance reversion index (50.22). As a result, improved in vivo tumor inhibition (up to 15-fold higher compared to free cisplatin) and decreased systemic toxicity was observed after treatment with Valproate-D-Nanogels. Overall, this nanogel can effectively inhibit cisplatin-resistance cancer through combined pathways and provides an effective approach for overcoming cisplatin-resistance in cancer treatment.

Targeted Antitumor Mechanism of C-PC/CMC-CD55sp Nanospheres in HeLa Cervical Cancer Cells

In vitro studies had shown that C-Phycocyanin (C-PC) inhibited cervical cancer HeLa cells growth. We constructed C-PC/CMC-CD55sp nanospheres using C-PC, Carboxymethyl Chitosan (CMC), and CD55 ligand peptide (CD55sp) to allow for targeted antitumor effects against HeLa cells in vitro and in vivo. The characteristics of the nanospheres were determined using FTIR, electron microscopy, and laser particle size analysis. Flow cytometry, laser confocal microscopy and small animal imaging system showed the targeting of C-PC/CMC-CD55sp nanospheres on HeLa cells. Subsequently, the proliferation and apoptosis were analyzed by Cell Counting Kit-8 (CCK-8), flow cytometry, TUNEL assay and electron microscopy. The expression of the apoptosis-related protein was determined using western blot. The stainings of Hematoxylin and Eosin (HE) were employed to evaluate the cell condition of tumor tissue sections. The cytokines in the blood in tumor-bearing nude mice was determined using ELISA. These results showed that C-PC/CMC-CD55sp nanospheres were successfully constructed and targeted HeLa cells. The constructed nanospheres were more effective than C-PC alone in inhibiting the proliferation and inducing apoptosis in HeLa cells. We also found that C-PC/CMC-CD55sp nanospheres had a significant inhibitory effect on the expression of antiapoptotic protein Bcl-2 and a promotion on the transformation of caspase 3 to cleaved caspase 3. C-PC/CMC-CD55sp nanospheres played an important role in tumor suppression, reduced the expression TGF-β, and increased IL-6 and TNF-α. This study demonstrates that the constructed new C-PC/CMC-CD55sp nanospheres exerted targeted antitumor effects in vivo and in vitro which provided a novel idea for application of C-PC, and provided experimental basis for comprehensive targeted treatment of tumors.

Ceramide lipid-based nanosuspension for enhanced delivery of docetaxel with synergistic antitumor efficiency

Ceramide (CE), a bioactive lipid with tumor suppression, has been widely used as a drug carrier and enhancer for cancer therapy. CE-based combination therapy was prone to be attractive in cancer therapy. In our previous study, the combination of CE and docetaxel (DTX) was proved to be an effective strategy for cancer therapy. To further improve the antitumor efficiency of DTX, the CE lipid-based nanosuspensions (LNS) was prepared for the delivery of DTX to exhibit synergistic therapeutic effect. The enhanced delivery and synergistic therapeutic effect of DTX-loaded CE-LNS (CE + DTX-LNS) were evaluated. CE + DTX-LNS exhibited spherical or ellipsoidal shape, uniform particle size distribution (108.1 ± 3.8 nm), sustained release characteristics and good stability in vitro. Notably, CE + DTX-LNS could effectively co-localize CE and DTX into same tumor cell and subsequently play synergistic cell damage effect compared with CE-LNS + DTX-LNS (p < 0.05). The in vivo fluorescence imaging results showed that CE + DTX-LNS could effectively prolong the in vivo circulation time and enhance the accumulation in tumor sites. Moreover, the antitumor efficacy of CE + DTX-LNS observed in B16 murine melanoma model was 93.94 ± 2.77%, significantly higher than that of CE-LNS, DTX-LNS, Duopafei® (p < 0.01) and CE-LNS + DTX-LNS (p < 0.05), respectively, demonstrating that co-delivery of CE and DTX into same tumor cell was the basis for enhanced synergistic therapeutic effect. Furthermore, histological examination of Blank-LNS showed no visible tissue toxicity compared to normal saline. Consequently, CE-LNS could effectively delivery DTX and CE + DTX-LNS exhibit synergistic inhibition of tumor growth due to the co-localization of CE and DTX. CE-LNS hold great potential to be an appropriate carrier for CE-based combination chemotherapy.

Nano-delivery system targeting to cancer stem cell cluster of differentiation biomarkers

Cancer stem cells (CSCs) are one of the most important origins of cancer progression and metastasis. CSCs have unique self-renewal properties and diverse cell membrane receptors that induced the resistance to the conventional chemotherapeutic agents. Therefore, the therapeutic removal of CSCs could result in the cancer cure with lack of recurrence and metastasis. In this regard, targeting CSCs in accordance to their specific biomarkers is a talented attitude in cancer therapy. Various CSCs surface biomarkers have been described, which some of them exhibited similarities on different cancer cell types, while the others are cancer specific and have just been reported on one or a few types of cancers. In this review, the importance of CSCs in cancer development and therapeutic response has been stated. Different CSCs cluster of differentiation (CD) biomarkers and their specific function and applications in the treatment of cancers have been discussed, Special attention has been made on targeted nano-delivery systems. In this regard, several examples have been illustrated concerning specific natural and artificial ligands against CSCs CD biomarkers that could be decorated on various nanoparticulated drug delivery systems to enhance therapeutic index of chemotherapeutic agents or anticancer gene therapy. The outlook of CSCs biomarkers discovery and therapeutic/diagnostic applications was discussed.

Recent developments in nanomedicine for melanoma treatment

Melanoma is a most aggressive skin cancer with limited therapeutic options and its incidence is increasing rapidly in recent years. The discovery and application of new targeted therapy agents have shown significant benefits. However, adverse side-effects and resistance to chemotherapy remain formidable challenges in the clinical treatment of malignant melanoma. Nanotherapeutics offers an important prospect of overcoming these drawbacks. The anti-tumoral applications of nanomedicine are varied, including those in chemotherapy, RNA interference, photothermal therapy, and photodynamic therapy. Furthermore, nanomedicine allows delivery of the effector structures into the tumor site via passive or active targeting, thereby allowing increased therapeutic specificity and reduced side effects. In this review, we summarize the latest developments in the application of nanocarrier-mediated targeted drug delivery to melanoma and nanomedicine-related clinical trials in melanoma treatment. We also discuss existing problems and opportunities for future developments, providing direction and new thoughts for further studies.

In vivo biodistribution, biocompatibility, and efficacy of sorafenib-loaded lipid-based nanosuspensions evaluated experimentally in cancer

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. In this study, sorafenib-loaded lipid-based nanosuspensions (sorafenib-LNS) were first developed as an intravenous injectable formulation to increase the efficacy of sorafenib against HCC. LNS were used as nanocarriers for sorafenib owing to their desired features in increasing the solubility and dissolution velocity, improving the bioavailability of sorafenib. Sorafenib-LNS were prepared by nanoprecipitation and consisted of spherical particles with a uniform size distribution (164.5 nm, polydispersity index =0.202) and negative zeta potential (-11.0 mV). The drug loading (DL) was 10.55%±0.16%. Sorafenib-LNS showed higher in vitro cytotoxicity than sorafenib against HepG2 cells (P<0.05) and Bel-7402 cells (P<0.05). The in vivo biodistribution, biocompatibility, and antitumor efficacy of sorafenib-LNS were evaluated in H22-bearing liver cancer xenograft murine model. The results showed that sorafenib-LNS (9 mg/kg) exhibited significantly higher antitumor efficacy by reducing the tumor volume compared with the sorafenib oral group (18 mg/kg, P<0.05) and sorafenib injection group (9 mg/kg, P<0.05). Furthermore, the results of the in vivo biodistribution experiments demonstrated that sorafenib-LNS injected into H22 tumor-bearing mice exhibited increased accumulation in the tumor tissue, which was confirmed by in vivo imaging. In the current experimental conditions, sorafenib-LNS did not show significant toxicity both in vitro and in vivo. These results suggest that sorafenib-LNS are a promising nanomedicine for treating HCC.

Evaluation of (188)Re-labeled NGR-VEGI protein for radioimaging and radiotherapy in mice bearing human fibrosarcoma HT-1080 xenografts

Vascular endothelial growth inhibitor (VEGI) is an anti-angiogenic protein, which includes three isoforms: VEGI-174, VEGI-192, and VEGI-251. The NGR (asparagine-glycine-arginine)-containing peptides can specifically bind to CD13 (Aminopeptidase N) receptor which is overexpressed in angiogenic blood vessels and tumor cells. In this study, a novel NGR-VEGI fusion protein was prepared and labeled with (188)Re for radioimaging and radiotherapy in mice bearing human fibrosarcoma HT-1080 xenografts. Single photon emission computerized tomography (SPECT) imaging results revealed that (188)Re-NGR-VEGI exhibits good tumor-to-background contrast in CD13-positive HT-1080 tumor xenografts. The CD13 specificity of (188)Re-NGR-VEGI was further verified by significant reduction of tumor uptake in HT-1080 tumor xenografts with co-injection of the non-radiolabeled NGR-VEGI protein. The biodistribution results demonstrated good tumor-to-muscle ratio (4.98 ± 0.25) of (188)Re-NGR-VEGI at 24 h, which is consistent with the results from SPECT imaging. For radiotherapy, 18.5 MBq of (188)Re-NGR-VEGI showed excellent tumor inhibition effect in HT-1080 tumor xenografts with no observable toxicity, which was confirmed by the tumor size change and hematoxylin and eosin (H&E) staining of major mouse organs. In conclusion, these data demonstrated that (188)Re-NGR-VEGI has the potential as a theranostic agent for CD13-targeted tumor imaging and therapy.

Preparation of a Thermosensitive Gel Composed of a mPEG-PLGA-PLL-cRGD Nanodrug Delivery System for Pancreatic Tumor Therapy

It is hypothesized that a gel (NP-Gel) composed of thermosensitive gel (Gel) and nanoparticles (NP) can prolong drug release time and overcome the drug resistance of pancreatic tumor cells. Paclitaxel (PTX)-loaded monomethoxy (polyethylene glycol)-poly(d,l-lactide-co-glycolide)-poly(l-lysine)-cyclic peptide (arginine-glycine-aspartic-glutamic-valine acid) (mPEG-PLGA-PLL-cRGD) NP and NP-Gel were designed, optimized, and characterized using dynamic light scattering, transmission electron microscopy, high efficiency liquid chromatography, and rheological analyses. Aspc-1/PTX cell was used in a cell uptake test. A 3D cell model was used to mimic PTX elimination in tissue. The in vivo sustained release and antitumor effects were studied in Aspc-1/PTX-loaded nude mice with xerographic and in situ tumors. The NP were 133.7 ± 28.3 nm with 85.03% entrapped efficiency, 1.612% loaded ratio, and suitable rheological properties. PTX was released as NP from NP-Gel, greatly prolonging the release and elimination times to afford long-term effects. NP-Gel enhanced the uptake of PTX by Aspc-1/PTX cells more than using NP or the Gel alone. Gel and NP-Gel remained solid in the tumor and stayed over 50 days versus the several days of NP in solution. NP-Gel exhibited a much higher inhibition rate in vivo than in solution, NP, or the Gel alone. In conclusion, the antitumor effects of NP-Gel might arise from synergic effects from NP and the Gel. NP primarily reversed drug resistance, while the Gel prolonged release time considerably in situ. This preparation proved effective with a very small PTX dose (250 μg/kg) and exhibited few toxic effects in normal tissue.

Preparation of pH Sensitive Pluronic-Docetaxel Conjugate Micelles to Balance the Stability and Controlled Release Issues

A novel polymer-drug conjugate was prepared by the chemical reaction between the copolymer Pluronic P123 and the docetaxel via a pH sensitive hydrazone bond. These pluronic P123-docetaxel (DTX) conjugates (P123-DTX) could form the stable drug-loaded materials that can self-assemble into the defined nano-micelles in aqueous solution because of their obvious amphiphilic property and low critical micelle concentration. The spherical morphology and particle size of the prepared nano-micelles were characterized by transmission electron microscopy and dynamic light scattering, respectively. Moreover, after the introduction of pH sensitive hydrazone bond, P123-DTX micelle showed a pH dependent drug release behavior. At pH 5.0 (in 48 h), the cumulative release amount of DTX were ~84.9%, which is about six times higher than that at pH 7.4. The prepared novel p123-DTX conjugates may offer a great benefit for drug delivery and controlling the drug release.

Co-delivery of doxorubicin and siRNA by a simplified platform with oligodeoxynucleotides as a drug carrier

The greatest challenge in combining chemotherapy and gene therapy is the construction of a suitable platform for the co-delivery of the drug and the therapeutic gene. In this study, a simplified and effective system for the co-loading and intracellular co-delivery of doxorubicin (Dox) and siRNA was developed. Oligodeoxynucleotides with CGA repeating units (CGA-ODNs) were introduced to load Dox. The loading mechanism was based on the ability of Dox to intercalate within double-stranded 5'-GC-3' or 5'-CG-3' sequences. Poly(ethyleneimine) (PEI) was used to condense siRNA and Dox loaded CGA-ODNs (CGA-ODNs-Dox) to obtain Dox and siRNA co-loaded nanocomplexes (PEI/CGA-ODNs-Dox&siRNA, PDR). The cellular uptake of PDR in A549 and HepG2 cells was 39.52% and 36.78%, respectively, indicating that the co-loading and co-delivery effect was achieved through the mono-loading method. An in vitro drug release study indicated that CMCS-poly(ethylene glycol) (PEG)-NGR (CPN) modified PDR (CPN-PDR) displayed a pH-triggered drug release property due to the reversed surface charge of CMCS in an acidic environment. Cellular uptake studies also confirmed that the disassembly of CPN-PDR was induced by an acidic pH in the extracellular matrix. Moreover, lysosomal escape of both Dox and siRNA was observed. Successful accumulation of Dox in the cell nucleus and siRNA in the cytoplasm was also demonstrated. Consequently, the novel construction of a simplified loading method and high co-delivery efficiency was proven to be a promising platform for the co-delivery of drug and siRNA.

Functionalized O-carboxymethyl-chitosan/polyethylenimine based novel dual pH-responsive nanocarriers for controlled co-delivery of DOX and genes

Dual pH-sensitive CDPD sequentially dissociates the outermost layer, CPN, and shows pH-triggered programmable release of DOX and genes.

Nanoscale drug delivery for taxanes based on the mechanism of multidrug resistance of cancer

Taxanes are one type of the most extensively used chemotherapeutic agents to treat cancers. However, their clinical use is severely limited by intrinsic and acquired resistance. A diverse variety of mechanisms has been implicated about taxane resistance, such as alterations of drug targets, overexpression of efflux transporters, defective apoptotic machineries, and barriers in drug transport. The deepening understanding of molecular mechanisms of taxane resistance has spawned a number of targets for reversing resistance. However, circumvention of taxane resistance would not only possess therapeutic potential, but also face with clinical challenge, which accelerates the development of optimal nanoscale delivery systems. This review highlights the current understanding on the mechanisms of taxane resistance, and provides a comprehensive analysis of various nanoscale delivery systems to reverse taxane resistance.