A dual-targeting drug co-delivery system for tumor chemo- and gene combined therapy

Nanoplatform-Mediated Autophagy Regulation and Combined Anti-Tumor Therapy for Resistant Tumors

The overall cancer incidence and death toll have been increasing worldwide. However, the conventional therapies have some obvious limitations, such as non-specific targeting, systemic toxic effects, especially the multidrug resistance (MDR) of tumors, in which, autophagy plays a vital role. Therefore, there is an urgent need for new treatments to reduce adverse reactions, improve the treatment efficacy and expand their therapeutic indications more effectively and accurately. Combination therapy based on autophagy regulators is a very feasible and important method to overcome tumor resistance and sensitize anti-tumor drugs. However, the less improved efficacy, more systemic toxicity and other problems limit its clinical application. Nanotechnology provides a good way to overcome this limitation. Co-delivery of autophagy regulators combined with anti-tumor drugs through nanoplatforms provides a good therapeutic strategy for the treatment of tumors, especially drug-resistant tumors. Notably, the nanomaterials with autophagy regulatory properties have broad therapeutic prospects as carrier platforms, especially in adjuvant therapy. However, further research is still necessary to overcome the difficulties such as the safety, biocompatibility, and side effects of nanomedicine. In addition, clinical research is also indispensable to confirm its application in tumor treatment.

Lipid nanoparticles for targeted delivery of anticancer therapeutics: Recent advances in development of siRNA and lipoprotein-mimicking nanocarriers

The limitations inherent in conventional cancer treatment methods have stimulated recent efforts towards the design of safe nanomedicines with high efficacy for combating cancer through various promising approaches. A plethora of nanoparticles has been introduced in the development of cancer nanomedicines. Among them, different lipid nanoparticles are attractive for use due to numerous advantages and unique opportunities, including biocompatibility and targeted drug delivery. However, a comprehensive understanding of nano-bio interactions is imperative to facilitate the translation of recent advancements in the development of cancer nanomedicines into clinical practice. In this contribution, we focus on lipoprotein-mimicking nanoparticles, which possess unique features and compositions facilitating drug transport through receptor binding mechanisms. Additionally, we describe potential applications of siRNA lipid nanoparticles in the future design of anticancer nanomedicines. Thus, this review highlights recent progress, challenges, and opportunities of lipid-based lipoprotein-mimicking nanoparticles and siRNA nanocarriers designed for the targeted delivery of anticancer therapeutic agents.

An enzyme-responsive and NIR-triggered lipid-polymer hybrid nanoplatform for synergistic photothermal/chemo cancer therapy

A combination of photothermal therapy (PTT) and chemotherapy is an emerging therapeutic strategy with promising clinical prospects in cancer treatment. Despite the huge progress achieved in the past years, a number of obstacles still hamper the therapeutic efficacy of this synergistic modality such as uneven heat distribution, lack of targetability of anti-cancer agents and dosage-related side effects. Thus, developing a nanoplatform for targeted drug delivery against cancer is of great necessity. Herein, a lipid-polymer hybrid nanosystem (LP/ID) based on polyethyleneimine (PEI)-lecithin-polyethylene glycol (PEG) was fabricated to co-load indocyanine green (ICG) and dichloroacetate (DCA) for combined photothermal/chemotherapy. DCA and ICG were linked to the PEI backbone to form a dense hydrophobic core through amide bonds and electrostatic interactions, which increased the payload of DCA and ICG as well as achieved enzyme-responsive drug release because of the overexpressed amidase in tumor cells. Lecithin and DSPE-PEG₂₀₀₀ self-assembled around the hydrophobic complexes to obtain prolonged blood circulation and attenuated systemic toxicity of the hybrid nanosystem. The prepared LP/ID exhibited favourable stability in a physiological environment, good tumor imaging properties, and satisfactory photothermal/chemotherapeutic performance. Moreover, LP/ID could also enhance the cellular uptake and tumor retention capacity in comparison with free drug administration. Notably, by co-loading two therapeutic agents with different anti-cancer mechanisms, an obvious inhibitory effect on tumor growth was observed with negligible damage to normal tissues and organs because of the synergistic photothermal/chemotherapy effect, indicating the great potential of LP/ID as a robust nanoplatform for cancer treatment.

Smart Drug Delivery Strategies for Cancer Therapy

Chemotherapy is one of the most widely used strategies to fight cancer, although it has disadvantages such as accumulation in healthy organs and lack of specificity by cancer cells (non-targeted molecules), among others, resulting in adverse effects on patients that limit the dose or follow-up with the same. However, the treatment can also fail due to the resistance mechanisms that cancer cells have to these agents. Because of these limitations, smart drug delivery strategies have been developed to overcome treatment challenges. These smart drug strategies are made with the aim of passively or actively releasing the drug into the tumor environment, increasing the uptake of the chemotherapeutic agent by the cancer cells, thus reducing the adverse effects on other vital organs. Also, these strategies can be guided with molecules on their surface that interact with the tumor microenvironment or with specific receptors on the cancer cell membrane, thus conferring high affinity. This mini review summarizes advances in the development of drug delivery techniques for cancer treatment, including different smart nanocarriers with single or multifunctional stimuli responsiveness. At the same time, we highlight the toxicity and delivery of these strategies in in vivo models. Despite innovation in smart delivery techniques, there are still biodistribution and customization challenges to be overcome in future research.

Insights on functionalized carbon nanotubes for cancer theranostics

Despite the exciting breakthroughs in medical technology, cancer still accounts for one of the principle triggers of death and conventional therapeutic modalities often fail to attain an effective cure. Recently, nanobiotechnology has made huge advancement in cancer therapy with gigantic application potential because of their ability in achieving precise and controlled drug release, elevating drug solubility and reducing adverse effects. Carbon nanotubes (CNTs), one of the most promising carbon-related nanomaterials, have already achieved much success in biomedical field. Due to their excellent optical property, thermal and electronic conductivity, easy functionalization ability and high drug loading capacity, CNTs can be applied in a multifunctional way for cancer treatment and diagnosis. In this review, we will give an overview of the recent progress of CNT-based drug delivery systems in cancer theranostics, which emphasizes their targetability to intracellular components of tumor cells and extracellular elements in tumor microenvironment. Moreover, a detailed introduction on how CNTs penetrate inside the tumor cells to reach their sites of action and achieve the therapeutic effects, as well as their diagnostic applications will be highlighted.

Connecting Cholesterol Efflux Factors to Lung Cancer Biology and Therapeutics

Cholesterol is a foundational molecule of biology. There is a long-standing interest in understanding how cholesterol metabolism is intertwined with cancer biology. In this review, we focus on the known connections between lung cancer and molecules mediating cholesterol efflux. A major take-home lesson is that the roles of many cholesterol efflux factors remain underexplored. It is our hope that this article would motivate others to investigate how cholesterol efflux factors contribute to lung cancer biology.

Reconstituted high density lipoprotein (rHDL), a versatile drug delivery nanoplatform for tumor targeted therapy

rHDL is a synthesized drug delivery nanoplatform exhibiting excellent biocompatibility, which possesses most of the advantages of HDL. rHDL shows almost no toxicity and can be degraded to non-toxic substances in vivo. The severe limitation of the application of various antitumor agents is mainly due to their low bioavailability, high toxicity, poor stability, etc. Favorably, antitumor drug-loaded rHDL nanoparticles (NPs), which are known as an important drug delivery system (DDS), help to change the situation a lot. This DDS shows an outstanding active-targeting ability towards tumor cells and improves the therapeutic effect during antitumor treatment while overcoming the shortcomings mentioned above. In the following text, we will mainly focus on the various applications of rHDL in tumor targeted therapy by describing the properties, preparation, receptor active-targeting ability and antitumor effects of antineoplastic drug-loaded rHDL NPs.

Surface engineering of nanomaterials with phospholipid-polyethylene glycol-derived functional conjugates for molecular imaging and targeted therapy

In recent years, phospholipid-polyethylene glycol-derived functional conjugates have been widely employed to decorate different nanomaterials, due to their excellent biocompatibility, long blood circulation characteristics, and specific targeting capability. Numerous in vivo studies have demonstrated that nanomedicines peripherally engineered with phospholipid-polyethylene glycol-derived functional conjugates show significantly increased selective and efficient internalization by target cells/tissues. Targeting moieties including small-molecule ligands, peptides, proteins, and antibodies are generally conjugated onto PEGylated phospholipids to decorate liposomes, micelles, hybrid nanoparticles, nanocomplexes, and nanoemulsions for targeted delivery of diagnostic and therapeutic agents to diseased sites. In this review, the synthesis methods of phospholipid-polyethylene glycol-derived functional conjugates, biophysicochemical properties of nanomedicines decorated with these conjugates, factors dominating their targeting efficiency, as well as their applications for in vivo molecular imaging and targeted therapy were summarized and discussed.

Co-delivery nanoparticles of doxorubicin and chloroquine for improving the anti-cancer effect in vitro

To increase the efficacy of small molecule chemotherapeutic drug (SMCD) and reduce its toxic and side effects, we selected two model drugs doxorubicin (DOX) and chloroquine (CQ). DOX is a SMCD and CQis a chemosensitizer with autophagy inhibition. Poly(lactic-co-glycolic acid) (PLGA) and alpha-tocopherol polyethylene glycol 1000 succinate were chosen as delivery carriers to design and prepare a novel type of drug co-delivery single-nanoparticles by emulsification-solvent volatilisation, named NP_DOX+CQ. The physicochemical properties of NP_DOX+CQ were characterised. Then A549 cells and A549/Taxol cells were used for the in vitro anti-cancer effect study. At the same time, cellular uptake, intracellular migration and anti-cancer mechanism of nanoparticles were studied. The NPs showed a uniform spherical shape with good dispersibility, and both drugs had good encapsulation efficiency and loading capacity. In all formulations, NP_DOX+CQ showed the highest in vitro cytotoxicity. The results showed that NPs could protect drugs from being recognised and excluded by P-glycoprotein (P-gp). Moreover, the results of the mechanistic study demonstrated that NPs were transported by autophagy process after being taken up by the cells. Therefore, during the migration of NP_DOX+CQ, CQ could exert its efficacy and block autophagy so that DOX would not be hit by autophagy. Western Blot results showed that NP_DOX+CQ had the best inhibition effect of autophagy. It can be concluded that the system can prevent the drug from being recognised and excluded by P-gp, and CQ blocks the process of autophagy so that the DOX is protected and more distributed to the nucleus of multidrug resistance (MDR) cell. The NP_DOX+CQ constructed in this study provides a feasible strategy for reversing MDR in tumour cells.

Co-delivery nanoparticles of anti-cancer drugs for improving chemotherapy efficacy

To achieve superior therapeutic efficacy, the combination chemotherapy using two or more anticancer drugs in clinical practice has been generally accepted as a feasible strategy. On account of the concept of combination chemotherapy, co-delivery of anticancer drugs with nanotechnology gradually becomes a desired strategy and one of the research frontiers on modern drug delivery. In recent years, nano drug co-delivery system (NDCDS), which loads at least two anticancer drugs with different physicochemical and pharmacological properties into a combination delivery system, has achieved rapid development. NDCDS synergistically inhibited the growth of the tumor compared with the free drugs. In this review, we highlighted the current state of co-delivery nanoparticles and the most commonly used nanomaterial, discussed challenges and strategies, and prospect future development.

Rerouting Native HDL to Predetermined Receptors for Improved Tumor-Targeted Gene Silencing Therapy

High-density lipoprotein (HDL) is an outstanding biocompatible nanovector for tumor-targeted delivery of multimodel drugs in cancer therapy. However, this seemingly promising delivery platform demonstrates an adverse accumulation in liver and adrenal due to the primary expression of natural target scavenger receptor class B type I (SR-BI), which overexpressed in malignant cells as well. Therefore, we endowed native HDLs with rerouting capacity, that is, enabling HDLs to get away from natural receptors (SR-BI) to selectively alternate tumor-rich receptors. The α_vβ₃-integrin specific cyclic-RGDyk peptide was conjugated with HDL-protein component apolipoprotein A-I (apoA-I), demonstrating high substitution degree of 26.2%. Afterward, RGD-modified apoA-I was introduced to fabricate cholesterol siRNA-loaded HDL nanoparticles (RGD-HDL/Ch-siRNA) for specific affinity with tumor angiogenesis and α_vβ₃ integrin on tumor surface. After preparation, RGD-HDL/Ch-siRNA shared desirable particle size, efficient siRNA protection during blood circulation, and favorable proton sponge effect. α_vβ₃ integrin-associated superior rerouting capacity, endocytosis pathway, and rapid endolysosome escape were confirmed both in vitro and in vivo. For targeted gene silencing therapy, Pokemon-specific siRNA (siPokemon) was introduced as RNA interference candidate; the enhanced antitumor efficacy and decreased Pokemon expression level were commendably confirmed by tumor growth inhibition, survival period extension, and western blot analysis. Collectively, cyclic-RGDyk modification endows native HDLs with rerouting capacity to specific α_vβ₃ integrin receptor, which provides a promising strategy to extend malignancy targeting potential of native HDL to a broader purview.

Nanomaterial-Enabled Cancer Therapy

While cancer remains the major cause of death worldwide, nanomaterial (NM)-based diagnosis and treatment modalities are showing remarkable potential to better tackle clinical oncology by effectively targeting therapeutic agents to tumors. NMs can selectively accumulate in solid tumors, and they can improve the bioavailability and reduce the toxicity of encapsulated cytotoxic agents. Additional noteworthy functions of NMs in cancer treatment include the delivery of contrast agents to image tumor sites, delivery of genetic materials for gene therapy, and co-delivery of multiple agents to achieve combination therapy or simultaneous diagnostic and therapeutic outcomes. Although several NM therapeutics have been successfully translated to clinical applications, the gap between the bench and the bedside remains ominously wide. Tumor heterogeneity and the disparity between pre-clinical and clinical studies have been identified as two of the major translational challenges of NM-based cancer therapies. Herein, we review a handful of recent research studies on the use of NMs in cancer therapy and imaging, with a limited discussion on the consequences of tumor heterogeneity and pre-clinical studies on translational research of NM-based delivery systems and propositions in the literature to overcome these challenges.

siRNA delivery using polyelectrolyte-gold nanoassemblies in neuronal cells for BACE1 gene silencing

Small interfering RNA (siRNA) mediated RNA interference is a versatile therapeutic tool for many intractable genetic disorders. Various nanoassemblies specifically designed to deliver the siRNAs could be utilized for efficient siRNA delivery which is one of the major concern for the success of this therapeutic. Thus, in the present study, polyelectrolyte-gold nanoassemblies (PE-Gold NAs) were selected for siRNA delivery of an in vitro verified siRNA. Three different polyelectrolytes (polyethyleneimine, citraconic anhydride modified poly (allylamine) hydrochloride and poly l-arginine) were used to formulate the PE-Gold NAs using the layer-by-layer technique. Successful physico-chemical characterizations of these PE-Gold NAs were performed using UV-Visible, FTIR, ¹H-NMR spectroscopies, XRD, TEM, DLS and Zeta potential measurements. In vitro studies for the cytotoxicity, the uptake of these nanoassemblies and the gene silencing were carried out using these PE-Gold NAs in N2a and NB4 1A3 (murine neuronal) cell lines. The three selected PE-Gold NAs showed significant BACE1 (β-site APP cleaving enzyme 1) gene silencing (50-60%). This work demonstrates the potential of PE-Gold NAs to deliver siRNA targeting BACE1 in neuronal cells. Finally, it was concluded that different polyelectrolytes used in the PE-Gold NAs achieve different gene silencing due to the variation in their delivery efficiencies.

A biomimetic Au@BSA-DTA nanocomposites-based contrast agent for computed tomography imaging

Early detection of cancer is increasingly important for being considered to increase the survival rate in the treatment process. The past decades years have witnessed the great progress in the biological detection application of gold nanoparticles. Herein, we reported a facile one-pot synthesis process to obtain gold nanoparticles (Au@BSA) with bovine serum albumin (BSA) as a biotemplate following with conjugation of diatrizoic acid (DTA) for a potential X-ray computed tomography (CT) imaging contrast agent (Au@BSA-DTA). The as-prepared biomimetic material was characterized systematically by several techniques. It was shown that the prepared biomaterial is colloid stable under the tested range of pH and temperature. The cell cytotoxicity assay, hemolytic assay and cell morphology observation showed that Au@BSA-DTA has good biocompatibility and hemocompatibility at a concentration of Au even up to 80μg/mL. Besides, the biomimetic material Au@BSA-DTA with double radiodense elements of Au and iodine displayed much stronger CT imaging effect compared with the traditional small molecule contrast agents, which paves the potential clinical application in cancer early diagnosis.

Targeting Nanocarriers with Anisamide: Fact or Artifact?

Encapsulating chemotherapeutics in nanoparticles can reduce the side effects of intravenous administration and improve their antitumor efficacy. Additionally, surface decoration of the nanocarriers with tumor-targeting ligands may enhance their specificity for cancer cells overexpressing the corresponding ligand-binding counterpart. The focus here is on anisamide, a low-molecular-weight benzamide derivative used as a tumor-directing moiety in functionalized nanosystems, based on its alleged interaction with Sigma receptors. The scintigraphic agents that initially inspired the use of anisamide for tumor targeting are described, and the published anisamide-tethered nanocarrier formulations are reviewed, together with a critical overview of the ligand's tumor-targeting properties. Moreover, anisamide's putative but dubious cellular target, the Sigma-1 receptor, is discussed with regard to its subcellular localization and implications in cancer. Data from in vivo studies reveal that the effect of anisamide on the antitumor efficacy of the decorated nanosystems varies considerably among the published reports. Together with the evidence questioning the interaction of anisamide with the Sigma receptors, the variability of anisamide's effect on the tumor deposition and the antitumor efficacy of the decorated drug carriers calls into question the extent of the ligand's tumor-targeting effect. Further research is necessary to elucidate the ligand's utility in tumor targeting.

Targeting SR-BI for Cancer Diagnostics, Imaging and Therapy

Scavenger receptor class B type I (SR-BI) plays an important role in trafficking cholesteryl esters between the core of high density lipoprotein and the liver. Interestingly, this integral membrane protein receptor is also implicated in the metabolism of cholesterol by cancer cells, whereby overexpression of SR-BI has been observed in a number of tumors and cancer cell lines, including breast and prostate cancers. Consequently, SR-BI has recently gained attention as a cancer biomarker and exciting target for the direct cytosolic delivery of therapeutic agents. This brief review highlights these key developments in SR-BI-targeted cancer therapies and imaging probes. Special attention is given to the exploration of high density lipoprotein nanomimetic platforms that take advantage of upregulated SR-BI expression to facilitate targeted drug-delivery and cancer diagnostics, and promising future directions in the development of these agents.