In vivo anti-tumor effect of PEG liposomal doxorubicin (DOX) in DOX-resistant tumor-bearing mice: Involvement of cytotoxic effect on vascular endothelial cells. J Control Release. 2009;133:4-10. [PMID: 18840484 DOI: 10.1016/j.jconrel.2008.09.008]

Manipulating Redox Homeostasis of Cancer Stem Cells Overcome Chemotherapeutic Resistance through Photoactivatable Biomimetic Nanodiscs

Tumor heterogeneity remains a significant obstacle in cancer therapy due to diverse cells with varying treatment responses. Cancer stem-like cells (CSCs) contribute significantly to intratumor heterogeneity, characterized by high tumorigenicity and chemoresistance. CSCs reside in the depth of the tumor, possessing low reactive oxygen species (ROS) levels and robust antioxidant defense systems to maintain self-renewal and stemness. A nanotherapeutic strategy is developed using tumor-penetrating peptide iRGD-modified high-density lipoprotein (HDL)-mimetic nanodiscs (IPCND) that ingeniously loaded with pyropheophorbide-a (Ppa), bis (2-hydroxyethyl) disulfide (S-S), and camptothecin (CPT) by synthesizing two amphiphilic drug-conjugated sphingomyelin derivatives. Photoactivatable Ppa can generate massive ROS which as intracellular signaling molecules effectively shut down self-renewal and trigger differentiation of the CSCs, while S-S is utilized to deplete GSH and sustainably imbalance redox homeostasis by reducing ROS clearance. Simultaneously, the depletion of GSH is accompanied by the release of CPT, which leads to subsequent cell death. This dual strategy successfully disturbed the redox equilibrium of CSCs, prompting their differentiation and boosting the ability of CPT to kill CSCs upon laser irradiation. Additionally, it demonstrated a synergistic anti-cancer effect by concurrently eliminating therapeutically resistant CSCs and bulk tumor cells, effectively suppressing tumor growth in CSC-enriched heterogeneous colon tumor mouse models.

Phosphatidylserine and/or Sialic Acid Modified Liposomes Increase Uptake by Tumor-associated Macrophages and Enhance the Anti-tumor Effect

DOX liposomes have better therapeutic effects and lower toxic side effects. The targeting ability of liposomes is one of the key factors affecting the therapeutic effect of DOX liposomes. This study developed two types of targeted liposomes. Sialic acid (SA)-modified liposomes were designed to target the highly expressed Siglec-1 receptor on tumor-associated macrophages surface. Phosphatidylserine (PS)-modified liposomes were designed to promote phagocytosis by monocyte-derived macrophages through PS apoptotic signaling. In order to assess and compare the therapeutic potential of different targeted pathways in the context of anti-tumor treatment, we compared four phosphatidylserine membrane materials (DOPS, DSPS, DPPS and DMPS) and found that liposomes prepared using DOPS as material could significantly improve the uptake ability of RAW264.7 cells for DOX liposomes. On this basis, normal DOX liposomes (CL-DOX) and SA-modified DOX liposomes (SAL-DOX), PS-modified DOX liposomes (PS-CL-DOX), SA and PS co-modified DOX liposomes (PS-SAL-DOX) were prepared. The anti-tumor cells function of each liposome on S180 and RAW264.7 in vitro was investigated, and it was found that SA on the surface of liposomes can increase the inhibitory effect. In vivo efficacy results exhibited that SAL-DOX and PS-CL-DOX were superior to other groups in terms of ability to inhibit tumor growth and tumor inhibition index, among which SAL-DOX had the best anti-tumor effect. Moreover, SAL-DOX group mice had high expression of IFN-γ as well as IL-12 factors, which could significantly inhibit mice tumor growth, improve the immune microenvironment of the tumor site, and have excellent targeted delivery potential.

Efficient Drug Loading Method for Poorly Water-Soluble Drug into Bicelles through Passive Diffusion

The bicelle, a type of solid lipid nanoparticle, comprises phospholipids with varying alkyl chain lengths and possesses the ability to solubilize poorly water-soluble drugs. Bicelle preparation is complicated and time-consuming because conventional drug-loading methods in bicelles require multiple rounds of thermal cycling or co-grinding with drugs and lipids. In this study, we proposed a simple drug-loading method for bicelles that utilizes passive diffusion. Drug-unloaded bicelles were placed inside a dialysis device and incubated in a saturated solution of ketoconazole (KTZ), which is a model drug. KTZ was successfully loaded into bare bicelles over time with morphological changes, and the final encapsulated concentration was dependent on the lipid concentration of the bicelles. When polyethylene glycol (PEG) chains of two different lengths (PEG2K and 5K) were incorporated into bicelles, PEG2k and PEG5k bicelles mitigated the morphological changes and improved the encapsulation rate. This mitigation of morphological changes enhanced the encapsulated drug concentration. Specifically, PEG5k bicelles, which exhibited the greatest prevention of morphological changes, had a lower encapsulated concentration after 24 h than that of PEG2k bicelles, indicating that PEGylation with a longer PEG chain length improved the loading capacity but decreased the encapsulation rate owing to the presence of a hydration layer of PEG. Thus, PEG with a certain length is more suitable for passive loading. Moreover, loading factors, such as temperature and vehicles used in the encapsulation process, affected the encapsulation rate of the drug. Taken together, the passive loading method offers high throughput with minimal resources, making it a potentially valuable approach during early drug development phases.

Bradykinin receptor participates in doxorubicin-induced cardiotoxicity by modulating iNOS signal pathway

Doxorubicin (DOX), an effective and broad-spectrum anthracycline antibiotic, is widely used in the treatment of numerous malignancies. However, dose-dependent cardiotoxicity limits the clinical application of DOX, and the molecular mechanisms are still unknown. In this study, we used the BK receptor B1/B2 double-knockout (B1B2 -/- ) mice to observe the role of BK receptor in cardiotoxicity induced by DOX and the underlying mechanisms. DOX induced myocardial injury with increased serum levels of AST, CK, and LDH, upregulated tissue expression of bradykinin B1/B2 receptor, FABP4 and iNOS, and downregulated expression of eNOS. However, these altered releases of myocardial enzyme and the expression level of iNOS were significantly prevented in the B1B2-/- mice. We concluded that the activation of both B1 and B2 receptors of BK were involved in the DOX-induced acute myocardial injury, possibly mediated through iNOS signaling pathways.

Targeted Fusogenic Liposomes for Effective Tumor Delivery and Penetration of Lipophilic Cargoes

Nanoparticle-based drug delivery has been widely used for effective anticancer treatment. However, a key challenge restricting the efficacy of nanotherapeutics is limited tissue penetration within solid tumors. Here, we report a targeted fusogenic liposome (TFL) that can selectively deliver lipophilic cargo to the plasma membranes of tumor cells. TFL is prepared by directly attaching tumor-targeting peptides to the surface of FL instead of the cationic moieties. The lipophilic cargo loaded in the membrane of TFL is transferred to the plasma membranes of tumor cells and subsequently packaged in the extracellular vesicles (EVs) released by the cells. Systemically administered TFL accumulates in the perivascular region of tumors, where the lipophilic cargo is unloaded to the tumor cell membranes and distributed autonomously throughout the tumor tissue via extracellular vesicle-mediated intercellular transfer. When loaded with a lipophilic pro-apoptotic drug, thapsigargin (Tg), TFL significantly inhibits tumor growth in a mouse colorectal cancer model. Furthermore, the combination treatment with TFL (Tg) potentiates the antitumor efficacy of FDA-approved liposomal doxorubicin, whose therapeutic effect is limited to perivascular regions without significant toxicity.

BioMOF-Based Anti-Cancer Drug Delivery Systems

A variety of nanomaterials have been developed specifically for biomedical applications, such as drug delivery in cancer treatment. These materials involve both synthetic and natural nanoparticles and nanofibers of varying dimensions. The efficacy of a drug delivery system (DDS) depends on its biocompatibility, intrinsic high surface area, high interconnected porosity, and chemical functionality. Recent advances in metal-organic framework (MOF) nanostructures have led to the achievement of these desirable features. MOFs consist of metal ions and organic linkers that are assembled in different geometries and can be produced in 0, 1, 2, or 3 dimensions. The defining features of MOFs are their outstanding surface area, interconnected porosity, and variable chemical functionality, which enable an endless range of modalities for loading drugs into their hierarchical structures. MOFs, coupled with biocompatibility requisites, are now regarded as highly successful DDSs for the treatment of diverse diseases. This review aims to present the development and applications of DDSs based on chemically-functionalized MOF nanostructures in the context of cancer treatment. A concise overview of the structure, synthesis, and mode of action of MOF-DDS is provided.

Oncogenic lncRNA MALAT-1 recruits E2F1 to upregulate RAD51 expression and thus promotes cell autophagy and tumor growth in non-small cell lung cancer

INTRODUCTION

LncRNA MALAT-1 expression is involved in regulating activities of non-small-cell lung cancer (NSCLC) cells. This study aimed to investigate the effects of lncRNA MALAT-1 on chemosensitivity of NSCLC cells by regulating autophagy.

METHODS

We first validated the expression of lncRNA MALAT-1 in NSCLC cell lines. NSCLC cell lines with high lncRNA MALAT-1 expression were exposed to doxorubicin (DOX) to assess chemosensitivity. Further LncMAP database retrieval and ChIP, RIP and luciferase activity assays were conducted to explore interplay between lncRNA MALAT-1, RAD51, and E2F1. Immunofluorescence staining was performed to evaluate formation of autophagosomes in NSCLC cells. Ectopic expression and knockdown methods were used for in vitro mechanism experiments and in vivo substantiation.

RESULTS

LncRNA MALAT-1 was overexpressed in NSCLC cells, and could promote NSCLC cell autophagy and inhibit its chemosensitivity. In vitro cell mechanism verification experiments showed that lncRNA MALAT-1 could recruit transcription factor E2F1 to bind to the promoter of RAD51, so as to promote the transcriptional expression of RAD51. In addition, cell function experiments in vitro showed that ectopically expressed lncRNA MALAT-1 promoted NSCLC cell autophagy and inhibited its chemosensitivity, while RAD51 knockdown negated its effect. Finally, in vivo animal experiments confirmed that lncRNA MALAT-1 silencing could impede the tumor growth.

CONCLUSIONS

Taken together, this study revealed that silencing lncRNA MALAT-1 enhanced chemosensitivity of NSCLC cells by promoting autophagy, highlighting a feasible approach to prevent chemoresistance in NSCLC treatment.

One-Step Pharmaceutical Preparation of PEG-Modified Exosomes Encapsulating Anti-Cancer Drugs by a High-Pressure Homogenization Technique

The use of exosomes encapsulating therapeutic agents for the treatment of diseases is of increasing interest. However, some concerns such as limited efficiency and scalability of conventional drug encapsulation methods to exosomes have still remained; thus, a new approach that enables encapsulation of therapeutic agents with superior efficiency and scalability is required. Herein, we used RAW264 macrophage cell-derived exosomes (RAW-Exos) and demonstrated that high-pressure homogenization (HPH) using a microfluidizer decreased their particle size without changing their morphology, the amount of exosomal marker proteins, and cellular uptake efficiency into RAW264 and colon-26 cancer cells. Moreover, HPH allowed for modification of polyethylene glycol (PEG)-conjugated lipids onto RAW-Exos, as well as encapsulation of the anti-cancer agent doxorubicin. Importantly, the doxorubicin encapsulation efficiency became higher upon increasing the process pressure and simultaneous HPH with PEG-lipids. Moreover, treatment with PEG-modified RAW-Exos encapsulating doxorubicin significantly suppressed tumor growth in colon-26-bearing mice. Taken together, these results suggest that HPH using a microfluidizer could be useful to prepare PEG-modified Exos encapsulating anti-cancer drugs via a one-step pharmaceutical process, and that the prepared functional Exos could be applied for the treatment of cancer in vivo.

Silk Fibroin-Coated Liposomes as Biomimetic Nanocarrier for Long-Term Release Delivery System in Cancer Therapy

Despite much progress in cancer therapy, conventional chemotherapy can cause poor biodistribution and adverse side-effects on healthy cells. Currently, various strategies are being developed for an effective chemotherapy delivery system. Silk fibroin (SF) is a natural protein used in a wide range of biomedical applications including cancer therapy due to its biocompatibility, biodegradability, and unique mechanical properties. In this study, SF-coated liposomes (SF-LPs) were prepared as a biomimetic drug carrier. Physicochemical properties of SF-LPs were characterized by Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering, zeta potential measurement, and transmission electron microscopy (TEM). In vitro release of SF-LPs loaded with doxorubicin (DOX-SF-LPs) was evaluated over 21 days. Anticancer activity of DOX-SF-LPs was determined against MCF-7 and MDA-MB231 cells using the MTT assay. SF-LPs containing 1% SF exhibited favorable characteristics as a drug carrier. SF coating modified the kinetics of drug release and reduced the cytotoxic effect against L929 fibroblasts as compared to the uncoated liposomes containing cationic lipid. DOX-SF-LPs showed anticancer activity against breast cancer cells after 48 h or 72 h at 20 μM of DOX. This approach provides a potential platform of long-term release that combines biocompatible SF and phospholipids for cancer therapy, achieving efficient drug delivery and reducing side-effects.

Liposomal Nanomedicine: Applications for Drug Delivery in Cancer Therapy

The increasing prevalence of cancer, a disease in which rapid and uncontrollable cell growth causes complication and tissue dysfunction, is one of the serious and tense concerns of scientists and physicians. Nowadays, cancer diagnosis and especially its effective treatment have been considered as one of the biggest challenges in health and medicine in the last century. Despite significant advances in drug discovery and delivery, their many adverse effects and inadequate specificity and sensitivity, which usually cause damage to healthy tissues and organs, have been great barriers in using them. Limitation in the duration and amount of these therapeutic agents' administration is also challenging. On the other hand, the incidence of tumor cells that are resistant to typical methods of cancer treatment, such as chemotherapy and radiotherapy, highlights the intense need for innovation, improvement, and development in antitumor drug properties. Liposomes have been suggested as a suitable candidate for drug delivery and cancer treatment in nanomedicine due to their ability to store drugs with different physical and chemical characteristics. Moreover, the high flexibility and potential of liposome structure for chemical modification by conjugating various polymers, ligands, and molecules is a significant pro for liposomes not only to enhance their pharmacological merits but also to improve the effectiveness of anticancer drugs. Liposomes can increase the sensitivity, specificity, and durability of these anti-malignant cell agents in the body and provide remarkable benefits to be applied in nanomedicines. We reviewed the discovery and development of liposomes focusing on their clinical applications to treat diverse sorts of cancers and diseases. How the properties of liposomal drugs can be improved and their opportunity and challenges for cancer therapy were also considered and discussed.

Targeting p53 for Melanoma Treatment: Counteracting Tumour Proliferation, Dissemination and Therapeutic Resistance

Simple Summary

Melanoma is a highly metastatic and therapy-resistant cancer and is therefore associated with low survival rates of patients. In melanoma, the inactivation of the wild-type form of the p53 tumour suppressor protein is a frequent event, mainly through interactions with MDM2 and MDMX. In this work, our recently disclosed p53-activating agent, SLMP53-2, displayed promising in vitro and in vivo antitumour activity, with particular impacts on melanoma migration and invasion. Moreover, SLMP53-2 (re)sensitized melanoma cells to clinically used chemotherapeutic agents, potentially overcoming the therapeutic resistance issue. As a whole, the p53 activator SLMP53-2 may represent a new therapeutic opportunity for melanoma, particularly in combination with MAPK pathway-targeting drugs.

Abstract

Melanoma is the deadliest form of skin cancer, primarily due to its high metastatic propensity and therapeutic resistance in advanced stages. The frequent inactivation of the p53 tumour suppressor protein in melanomagenesis may predict promising outcomes for p53 activators in melanoma therapy. Herein, we aimed to investigate the antitumor potential of the p53-activating agent SLMP53-2 against melanoma. Two- and three-dimensional cell cultures and xenograft mouse models were used to unveil the antitumor activity and the underlying molecular mechanism of SLMP53-2 in melanoma. SLMP53-2 inhibited the growth of human melanoma cells in a p53-dependent manner through induction of cell cycle arrest and apoptosis. Notably, SLMP53-2 induced p53 stabilization by disrupting the p53–MDM2 interaction, enhancing p53 transcriptional activity. It also promoted the expression of p53-regulated microRNAs (miRNAs), including miR-145 and miR-23a. Moreover, it displayed anti-invasive and antimigratory properties in melanoma cells by inhibiting the epithelial-to-mesenchymal transition (EMT), angiogenesis and extracellular lactate production. Importantly, SLMP53-2 did not induce resistance in melanoma cells. Additionally, it synergized with vemurafenib, dacarbazine and cisplatin, and resensitized vemurafenib-resistant cells. SLMP53-2 also exhibited antitumor activity in human melanoma xenograft mouse models by repressing cell proliferation and EMT while stimulating apoptosis. This work discloses the p53-activating agent SLMP53-2 which has promising therapeutic potential in advanced melanoma, either as a single agent or in combination therapy. By targeting p53, SLMP53-2 may counteract major features of melanoma aggressiveness.

Lipid bubbles combined with low-intensity ultrasound enhance the intratumoral accumulation and antitumor effect of pegylated liposomal doxorubicin in vivo

Pegylated liposomal doxorubicin (PLD) is a representative nanomedicine that has improved tumor selectivity and safety profile. However, the therapeutic superiority of PLD over conventional doxorubicin has been reported to be insignificant in clinical medicine. Combination treatment with microbubbles and ultrasound (US) is a promising strategy for enhancing the antitumor effects of chemotherapeutics by improving drug delivery. Recently, several preclinical studies have shown the drug delivery potential of lipid bubbles (LBs), newly developed monolayer microbubbles, in combination with low-intensity US (LIUS). This study aimed to elucidate whether the combined use of LBs and LIUS enhanced the intratumoral accumulation and antitumor effect of PLD in syngeneic mouse tumor models. Contrast-enhanced US imaging using LBs showed a significant decrease in contrast enhancement after LIUS, indicating that LIUS exposure induced the destruction of LBs in the tumor tissue. A quantitative evaluation revealed that the combined use of LBs and LIUS improved the intratumoral accumulation of PLD. Furthermore, tumor growth was inhibited by combined treatment with PLD, LBs, and LIUS. Therefore, the combined use of LBs and LIUS enhanced the antitumor effect of PLD by increasing its accumulation in the tumor tissue. In conclusion, the present study provides important evidence that the combination of LBs and LIUS is an effective method for enhancing the intratumoral delivery and antitumor effect of PLD in vivo.

Lipidated Peptidomimetic Ligand-Functionalized HER2 Targeted Liposome as Nano-Carrier Designed for Doxorubicin Delivery in Cancer Therapy

The therapeutic index of chemotherapeutic agents can be improved by the use of nano-carrier-mediated chemotherapeutic delivery. Ligand-targeted drug delivery can be used to achieve selective and specific delivery of chemotherapeutic agents to cancer cells. In this study, we prepared a peptidomimetic conjugate (SA-5)-tagged doxorubicin (Dox) incorporated liposome (LP) formulation (SA-5-Dox-LP) to evaluate the targeted delivery potential of SA-5 in human epidermal growth factor receptor-2 (HER2) overexpressed non-small-cell lung cancer (NSCLC) and breast cancer cell lines. The liposome was prepared using thin lipid film hydration and was characterized for particle size, encapsulation efficiency, cell viability, and targeted cellular uptake. In vivo evaluation of the liposomal formulation was performed in a mice model of NSCLC. The cell viability studies revealed that targeted SA-5-Dox-LP showed better antiproliferative activity than non-targeted Dox liposomes (Dox-LP). HER2-targeted liposome delivery showed selective cellular uptake compared to non-targeted liposomes on cancer cells. In vitro drug release studies indicated that Dox was released slowly from the formulations over 24 h, and there was no difference in Dox release between Dox-LP formulation and SA-5-Dox-LP formulation. In vivo studies in an NSCLC model of mice indicated that SA-5-Dox-LP could reduce the lung tumors significantly compared to vehicle control and Dox. In conclusion, this study demonstrated that the SA-5-Dox-LP liposome has the potential to increase therapeutic efficiency and targeted delivery of Dox in HER2 overexpressing cancer.

Reversal of Multidrug Resistance by Apolipoprotein A1-Modified Doxorubicin Liposome for Breast Cancer Treatment

Multidrug resistance (MDR) remains a major problem in cancer therapy and is characterized by the overexpression of p-glycoprotein (P-gp) efflux pump, upregulation of anti-apoptotic proteins or downregulation of pro-apoptotic proteins. In this study, an Apolipoprotein A1 (ApoA1)-modified cationic liposome containing a synthetic cationic lipid and cholesterol was developed for the delivery of a small-molecule chemotherapeutic drug, doxorubicin (Dox) to treat MDR tumor. The liposome-modified by ApoA1 was found to promote drug uptake and elicit better therapeutic effects than free Dox and liposome in MCF-7/ADR cells. Further, loading Dox into the present ApoA1-liposome systems enabled a burst release at the tumor location, resulting in enhanced anti-tumor effects and reduced off-target effects. More importantly, ApoA1-lip/Dox caused fewer adverse effects on cardiac function and other organs in 4T1 subcutaneous xenograft models. These features indicate that the designed liposomes represent a promising strategy for the reversal of MDR in cancer treatment.

Doxorubicin Hydrochloride-Loaded Nonionic Surfactant Vesicles to Treat Metastatic and Non-Metastatic Breast Cancer

Doxorubicin hydrochloride (DOX) is currently used to treat orthotropic and metastatic breast cancer. Because of its side effects, the use of DOX in cancer patients is sometimes limited; for this reason, several scientists tried designing drug delivery systems which can improve drug therapeutic efficacy and decrease its side effects. In this study, we designed, prepared, and physiochemically characterized nonionic surfactant vesicles (NSVs) which are obtained by self-assembling different combinations of hydrophilic (Tween 20) and hydrophobic (Span 20) surfactants, with cholesterol. DOX was loaded in NSVs using a passive and pH gradient remote loading procedure, which increased drug loading from ∼1 to ∼45%. NSVs were analyzed in terms of size, shape, size distribution, zeta potential, long-term stability, entrapment efficiency, and release kinetics, and nanocarriers having the best physiochemical parameters were selected for further in vitro tests. NSVs with and without DOX were stable and showed a sustained drug release up to 72 h. In vitro studies, with MCF-7 and MDA MB 468 cells, demonstrated that NSVs, containing Span 20, were better internalized in MCF-7 and MDA MB 468 cells than NSVs with Tween 20. NSVs increased the anticancer effect of DOX in MCF-7 and MDA MB 468 cells, and this effect is time and dose dependent. In vitro studies using metastatic and nonmetastatic breast cancer cells also demonstrated that NSVs, containing Span 20, had higher cytotoxicity than NSVs with Tween 20. The resulting data suggested that DOX-loaded NSVs could be a promising nanocarrier for the potential treatment of metastatic breast cancer.

Treatment of Lung Cancer by Peptide-Modified Liposomal Irinotecan Endowed with Tumor Penetration and NF-κB Inhibitory Activities

Current chemotherapy for lung cancer achieved limited efficacy due to poor tumor targeting and tissue penetration. Another obstacle in the therapy is activated nuclear factor-κB (NF-κB) in tumor cells, which plays a crucial role in promotion of antiapoptosis and drug resistance. In this study, we utilized a multifunctional liposome loaded with irinotecan and surface modified with a cell-permeable NF-κB inhibitor (CB5005), for treatment of non-small-cell lung carcinoma. CB5005 downregulated the level of NF-κB-related protein in the nuclei of A549 cells, and increased cellular uptake of the modified liposomes. In vivo antitumor activity in mice bearing A549 xenografts revealed that modification with CB5005 significantly improved the tumor inhibition rate of irinotecan. Immunohistochemical assays showed that the tumors treated with CB5005-modified liposomes possessed the most apoptotic cells and the lowest level of p50 in the cell nuclei. These results strongly suggest that antitumor efficacy of the irinotecan liposomes can be enhanced by tumor-penetrating and NF-κB-inhibiting functions of CB5005. Consequently, CB5005-modified liposomes provide a possible synergistic therapy for lung cancer, and would also be appropriate for other types of tumors associated with elevated NF-κB activity.

Significance of Ligand-Anchored Polymers for Drug Targeting in the Treatment of Colonic Disorders

Treatment of a variety of bowel diseases like Crohn's disease, ulcerative colitis, colonic cancers, colonic pathologies, and systemic delivery of drugs at the target sites can be done with the help of targeted drug delivery technique. Conventional colon specific drug delivery systems lack specificity and release significant amount of drug prior reaching the target site. Hence, efficient drug delivery system that ensures effective release of the drug at the colon is still a sought after research arena. Ligand anchored therapy is a strong and effective approach to execute drug delivery in selective target cells, for both, diagnostic, as well as therapeutic reasons. Compared to the regular drugs, such ligand anchored therapy provides added benefit of minimum toxicity and few side effects. Discovery of overexpressed receptors on diseased cells, as compared to healthy cells led to the emergence of active drug targeting. Further, drug resistance constitutes one of the major reasons of the failure of chemotherapy and presents a major obstacle for the effective treatment. The reason behind drug resistance is exposure of pathological cells/pathogens to sub-therapeutic levels of drugs due lack of specificity of therapeutics. Active targeting, specifically taken up by the target cells, can warrant exposure of pathological cells/pathogens to high drug load at the target and sparing non-target cells hence minimal damage to normal cells and least chance of drug resistance. Many ligands like antibodies, aptamers, peptides, folate, and transferrin have been discovered in the past few years. The design of nanocarriers can be incorporated with many different functions which enables functions like imaging and triggered intracellular drug release. The present review article focuses on advances in ligand anchored therapy and its significance on the progress of targeted nanocarriers. It will also establish novel concepts like multi-targeting and multi-functional nanocarriers for the treatment of colonic disorders.

A. I. Colorectal cancer stem cells: a review of targeted drug delivery by gold nanoparticles

The proposed schematic mechanismviawhich 5-fluorouracil-loaded gold nanoparticles conjugated with CD133 antibody target colorectal cancer stem cells.

Targeted therapy in chronic diseases using nanomaterial-based drug delivery vehicles

The application of nanomedicines is increasing rapidly with the promise of targeted and efficient drug delivery. Nanomedicines address the shortcomings of conventional therapy, as evidenced by several preclinical and clinical investigations indicating site-specific drug delivery, reduced side effects, and better treatment outcome. The development of suitable and biocompatible drug delivery vehicles is a prerequisite that has been successfully achieved by using simple and functionalized liposomes, nanoparticles, hydrogels, micelles, dendrimers, and mesoporous particles. A variety of drug delivery vehicles have been established for the targeted and controlled delivery of therapeutic agents in a wide range of chronic diseases, such as diabetes, cancer, atherosclerosis, myocardial ischemia, asthma, pulmonary tuberculosis, Parkinson's disease, and Alzheimer's disease. After successful outcomes in preclinical and clinical trials, many of these drugs have been marketed for human use, such as Abraxane®, Caelyx®, Mepact®, Myocet®, Emend®, and Rapamune®. Apart from drugs/compounds, novel therapeutic agents, such as peptides, nucleic acids (DNA and RNA), and genes have also shown potential to be used as nanomedicines for the treatment of several chronic ailments. However, a large number of extensive clinical trials are still needed to ensure the short-term and long-term effects of nanomedicines in humans. This review discusses the advantages of various drug delivery vehicles for better understanding of their utility in terms of current medical needs. Furthermore, the application of a wide range of nanomedicines is also described in the context of major chronic diseases.

Functionalized Eu(III)-based nanoscale metal-organic framework for enhanced targeted anticancer therapy

To improve the cancer targeting and anticancer efficacy, the multifunctional Eu-based metal-organic framework (EuBTC) is post-synthetically modified with a targeting moiety folic acid and a zinc phthalocyanine photosensitizer. In addition, this nanosphere is also applied as a drug delivery system to load the chemical drug doxorubicin. Electron microscopy, powder X-ray diffraction and infrared spectometry demonstrated the formation of these multifunctional nanospheres (DOX). Our nanospheres kept the high singlet oxygen quantum yield of zinc phthalocyanine. Additionally, Cell viability experiments demonstrated the biosafety of EuBTC and the enhanced anticancer effect of DOX@FA-EuBTC-Pc under light irradiation. In short, these well-arranged DOX@FA-Eu-BTC-Pcs exhibit as promising drug delivery systems for enhanced targeted anticancer therapy.

LS. Diverse Targeted Approaches to Battle Multidrug Resistance in Cancer

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The efficacy of successful cancer therapies is frequently hindered by the development of drug resistance in the tumor. The term ‘drug resistance’ is used to illustrate the decreased effectiveness of a drug in curing a disease or alleviating the symptoms of the patient. This phenomenon helps tumors to survive the damage caused by a specific drug or group of drugs. In this context, studying the mechanisms of drug resistance and applying this information to design customized treatment regimens can improve therapeutic efficacy as well as the curative outcome. Over the years, numerous Multidrug Resistance (MDR) mechanisms have been recognized and tremendous effort has been put into developing agents to address them. The integration of data emerging from the elucidation of molecular and biochemical pathways and specific tumor-associated factors has shown tremendous promise within the oncology community for improving patient outcomes. In this review, we provide an overview of the utility of these molecular and biochemical signaling processes as well as tumor-associated factors associated with MDR, for the rational selection of cancer treatment strategies.

Improving anticancer activity towards colon cancer cells with a new p53-activating agent

BACKGROUND AND PURPOSE

Impairment of the tumour suppressor p53 pathway is a major event in human cancers, making p53 activation one of the most attractive therapeutic strategies to halt cancer. Here, we have identified a new selective p53 activator and investigated its potential as an anticancer agent.

EXPERIMENTAL APPROACH

Anti-proliferative activity of the (R)-tryptophanol-derived bicyclic lactam SYNAP was evaluated in a range of human cancer cells with different p53 status. The anticancer activity and mechanism of action of SYNAP was studied in two- and three-dimensional models of human colon adenocarcinoma HCT116 cells with wild-type p53 and corresponding p53-null isogenic derivative cells, alone and in combination with known chemotherapeutic agents.

KEY RESULTS

SYNAP showed anti-proliferative effect in human cancer cells dependent on p53 status. In HCT116 cells, SYNAP caused p53-dependent growth inhibition, associated with cell cycle arrest and apoptosis, anti-migratory activity and regulation of the expression of p53 transcriptional targets. Data also indicated that SYNAP targeted p53, inhibiting its interaction with its endogenous inhibitors, murine double minute (MDM)2 and MDMX. Moreover, SYNAP sensitized colon cancer cells to the cytotoxic effect of known chemotherapeutic agents. SYNAP did not induce acquired or cross-resistance and re-sensitized doxorubicin-resistant colon cancer cells to chemotherapy. Additionally, SYNAP was non-genotoxic and had low cytotoxicity against normal cells.

CONCLUSION AND IMPLICATIONS

SYNAP revealed encouraging anticancer activity, either alone or in combination with known chemotherapeutic agents, in colon cancer cells. Apart from its promising application in cancer therapy, SYNAP may provide a starting point for improved p53 activators.

Liposomal Formulations to Modulate the Tumour Microenvironment and Antitumour Immune Response

Tumours are complex systems of genetically diverse malignant cells that proliferate in the presence of a heterogeneous microenvironment consisting of host derived microvasculature, stromal, and immune cells. The components of the tumour microenvironment (TME) communicate with each other and with cancer cells, to regulate cellular processes that can inhibit, as well as enhance, tumour growth. Therapeutic strategies have been developed to modulate the TME and cancer-associated immune response. However, modulating compounds are often insoluble (aqueous solubility of less than 1 mg/mL) and have suboptimal pharmacokinetics that prevent therapeutically relevant drug concentrations from reaching the appropriate sites within the tumour. Nanomedicines and, in particular, liposomal formulations of relevant drug candidates, define clinically meaningful drug delivery systems that have the potential to ensure that the right drug candidate is delivered to the right area within tumours at the right time. Following encapsulation in liposomes, drug candidates often display extended plasma half-lives, higher plasma concentrations and may accumulate directly in the tumour tissue. Liposomes can normalise the tumour blood vessel structure and enhance the immunogenicity of tumour cell death; relatively unrecognised impacts associated with using liposomal formulations. This review describes liposomal formulations that affect components of the TME. A focus is placed on formulations which are approved for use in the clinic. The concept of tumour immunogenicity, and how liposomes may enhance radiation and chemotherapy-induced immunogenic cell death (ICD), is discussed. Liposomes are currently an indispensable tool in the treatment of cancer, and their contribution to cancer therapy may gain even further importance by incorporating modulators of the TME and the cancer-associated immune response.

One-Step Preparation of pH-Responsive Polymeric Nanogels as Intelligent Drug Delivery Systems for Tumor Therapy

In this work, pH-responsive polypeptide-based nanogels are reported as potential drug delivery systems. By the formation of pH-sensitive benzoic imine bonds, pH-responsive nanogels are constructed using hydrophilic methoxy poly(ethylene glycol)- b-poly[ N-[ N-(2-aminoethyl)-2-aminoethyl]-l-glutamate] (MPEG- b-PNLG) and hydrophobic terephthalaldehyde (TPA) as a cross-linker. At pH 7.4, MPEG- b-PNLG nanogels exhibit high stabilities with hydrophobic inner cores, which allow encapsulation of hydrophobic therapeutic agents. Under tumoral acidic environments (pH ∼6.4), the cleavage of benzoic imine bonds induces the destruction of MPEG- b-PNLG nanogels and leads to rapid release of their payloads. The formation and pH sensitivity of the nanogels are investigated by dynamic light scattering. These nanogels exhibit excellent stabilities in the presence of salt or against dilution. The globular morphologies of the nanogels are confirmed using transmission electron microscopy. Doxorubicin is used as a model drug to evaluate drug encapsulation and release. Finally, the anticancer activities of the drug-encapsulated nanogels are assessed in vitro.

Elimination of established tumors with nanodisc-based combination chemoimmunotherapy

Although immune checkpoint blockade has shown initial success for various cancers, only a small subset of patients benefits from this therapy. Some chemotherapeutic drugs have been reported to induce antitumor T cell responses, prompting a number of clinical trials on combination chemoimmunotherapy. However, how to achieve potent immune activation with traditional chemotherapeutics in a manner that is safe, effective, and compatible with immunotherapy remains unclear. We show that high-density lipoprotein-mimicking nanodiscs loaded with doxorubicin (DOX), a widely used chemotherapeutic agent, can potentiate immune checkpoint blockade in murine tumor models. Delivery of DOX via nanodiscs triggered immunogenic cell death of cancer cells and exerted antitumor efficacy without any overt off-target side effects. "Priming" tumors with DOX-carrying nanodiscs elicited robust antitumor CD8+ T cell responses while broadening their epitope recognition to tumor-associated antigens, neoantigens, and intact whole tumor cells. Combination chemoimmunotherapy with nanodiscs plus anti-programmed death 1 therapy induced complete regression of established CT26 and MC38 colon carcinoma tumors in 80 to 88% of animals and protected survivors against tumor recurrence. Our work provides a new, generalizable framework for using nanoparticle-based chemotherapy to initiate antitumor immunity and sensitize tumors to immune checkpoint blockade.

Visfatin mediates doxorubicin resistance in human colorectal cancer cells via up regulation of multidrug resistance 1 (MDR1)

Colorectal cancer (CRC) is one of the prevalent and deadly cancers worldwide. Chemotherapy resistance is one of the most challenging problems for CRC and other cancer treatments. Recent studies indicated that increasing levels of visfatin are correlated with worse clinical prognosis of CRC patients, while the effects and mechanisms of visfatin on progression of CRC remain unclear. Our present study established doxorubicin (Dox)-resistant CRC HCT-116 and SW480 cells (named HCT-116 Dox/R and SW480 Dox/R). The expression of visfatin, while not IL-6, IL-8, or TGF-β, in CRC Dox-resistant cells was significantly greater than that in their parental cells, while knockdown of visfatin by its specific siRNAs can elevate Dox sensitivity of CRC-resistant cells. In addition, si-visfatin can significantly down regulate the expression of multidrug resistance 1 (MDR1), while not multidrug resistance-associated protein 1 or lung resistance-related protein, in both HCT-116 Dox/R and SW480 Dox/R cells. Visfatin can regulate the transcription of MDR1 via modulating its promoter activities. Si-visfatin can also decrease the activation and nuclear localization of p65, one of the most important transcription factors for the expression of MDR1. Chromatin immunoprecipitation (ChIP) indicated that si-visfatin can suppress the binding between p65 and MDR1 promoter. Collectively, our present study revealed that visfatin mediates the Dox resistance of CRC cells via up regulation of MDR1. It indicated that targeted inhibition of visfatin might be helpful for overcoming Dox resistance of CRC therapy.

The Use of Anthracyclines for Therapy of CNS Tumors

Despite being long lived, anthracyclines remain the “evergreen” drugs in clinical practice of oncology, showing a potent effect in inhibiting cell growth in many types of tumors, including brain neoplasms. Unfortunately, they suffer from a poor penetration into the brain when intravenously administered due to multidrug resistance mechanism, which hampers their delivery across the blood brain barrier.

In this paper, we summarize the current literature on the role of anthracyclines in cancer therapy and highlight recent efforts on 1) development of tumor cell resistance to anthracyclines and 2) the new approaches to brain drug delivery across the blood brain barrier.

Insight to drug delivery aspects for colorectal cancer

Colorectal cancer (CRC) is the third most common cancer diagnosed worldwide in human beings. Surgery, chemotherapy, radiotherapy and targeted therapies are the conventional four approaches which are currently used for the treatment of CRC. The site specific delivery of chemotherapeutics to their site of action would increase effectiveness with reducing side effects. Targeted oral drug delivery systems based on polysaccharides are being investigated to target and deliver chemotherapeutic and chemopreventive agents directly to colon and rectum. Site-specific drug delivery to colon increases its concentration at the target site, and thus requires a lower dose and hence abridged side effects. Some novel therapies are also briefly discussed in article such as receptor (epidermal growth factor receptor, folate receptor, wheat germ agglutinin, VEGF receptor, hyaluronic acid receptor) based targeting therapy; colon targeted proapoptotic anticancer drug delivery system, gene therapy. Even though good treatment options are available for CRC, the ultimate therapeutic approach is to avert the incidence of CRC. It was also found that CRCs could be prevented by diet and nutrition such as calcium, vitamin D, curcumin, quercetin and fish oil supplements. Immunotherapy and vaccination are used nowadays which are showing better results against CRC.

How can nanomedicines overcome cellular-based anticancer drug resistance?

This review discusses the mechanisms of anticancer drug resistance according to its cellular level of action and outlines the nanomedicine-based strategies adopted to overcome it.

Improvement in the drug delivery and anti-tumor efficacy of PEGylated liposomal doxorubicin by targeting RNA aptamers in mice bearing breast tumor model

Targeted delivery by ligands such as aptamers, is a promising method to increase the efficiency of PEGylated-liposomal doxorubicin (PL-Dox). In this study, we have successfully conjugated our recently developed anti-breast cancer RNA aptamer (TSA14) to the surface of PL-Dox and characterized for their size, zeta potential, Dox percent encapsulation and release properties in the presence of fetal bovine serum. In vitro experiments showed that aptamer could improve cellular uptake and cytotoxicity of PL-Dox in TUBO breast cell line. In mice bearing TUBO breast tumor, although, the doxorubicin plasma level of liposomal doxorubicin did not significantly change after modification of nanoparticles with aptamer, however, much higher tumor accumulation of Dox as compared with non-targeted liposomes proved the tumor-targeting capability of aptamers. In the same way, aptamer-PL-Dox improved anti-tumor efficiency of liposomes in TUBO breast tumor in mice compared to non-targeted liposomes. Overall, the results showed that aptamer decoration of PL-Dox could significantly improve selectivity and the therapeutic efficacy of liposomal DOX and merits further investigation.

A novel injectable phospholipid gel co-loaded with doxorubicin and bromotetrandrine for resistant breast cancer treatment by intratumoral injection

Systemically administered anticancer treatments were greatly limited by extensive side effects mainly due to nonspecific distributions in vivo, and multidrug resistance in various tumors. A phospholipids-based in situ-forming gel platform has been developed for the concurrent delivery of doxorubicin (DOX) and bromotetrandrin (W198). Phospholipid gel containing DOX and W198 remained in a solution (sol) state before injection and underwent rapid gelation after injection in vivo. The release of DOX and W198 from phospholipid gel (PG) was sustained in vitro for over 20 days (d). DOX and W198 from PG achieved prolonged release for over two weeks in rats via subcutaneous injection. Compared with repeated injections of free drug, eliminated cardiac toxicity and less bone marrow inhibition were observed for DOX and W198-loaded PG (DOX/W198-PG) in normal rats via subcutaneous injection. Also, a single intratumoral injection of DOX/W198-PG in the resistant MCF-7/Adr xenograft-bearing mice showed much better antitumor efficacy compared to other treatment groups. In sum, DOX/W198-PG was well demonstrated to achieve sustained drug release both in vitro and in vivo with eliminated toxicity and improved antitumor efficacy by reversing the multidrug resistance in breast cancers.

Nanoparticle approaches to combating drug resistance

Multidrug resistance (MDR) among cancer cells is a serious impediment to the success of conventional chemotherapy. The emergence of nanomedicine demonstrates great promise in overcoming MDR through multiple mechanisms. Nanoparticles have been shown to overcome the MDR at the tissue level through increased intratumoral accumulation resulting from enhanced permeation and retention, neovascular cell targeting, and externally triggered local drug release. Nanoparticles have also demonstrated the ability to overcome the MDR at the cellular/subcellular level by enhancing intracellular drug accumulation, improving drug-target accessibility, or even interfering with existing MDR mechanisms.

Evaluation of the potential of doxorubicin loaded microbubbles as a theranostic modality using a murine tumor model

In this study, a novel phospholipid-based microbubble formulation containing doxorubicin and perfluoropropane gas (DLMB) was developed. The DLMBs were prepared by mechanical agitation of a phospholipid dispersion in the presence of perfluoropropane (PFP) gas. An anionic phospholipid, distearoyl phosphatidylglycerol (DSPG) was selected to load doxorubicin in the microbubbles by means of electrostatic interaction. The particle size, zeta potential, echogenicity and stability of the DLMBs were measured. Drug loading was ⩾ 92%. The potential of the DLMBs for use as a theranostic modality was evaluated in tumor bearing mice. Gas chromatography analysis of PFP showed significant enhancement of PFP retention when doxorubicin was used at concentrations of 10-82% equivalent to DSPG. The inhibitory effects on the proliferation of B16BL6 melanoma murine cells in vitro were enhanced using a combination of ultrasound (US) irradiation and DLMBs. Moreover, in vivo DLMBs in combination with (US) irradiation significantly inhibited the growth of B16BL6 melanoma tumor in mice. Additionally, US echo imaging showed high contrast enhancement of the DLMBs in the tumor vasculature. These results suggest that DLMBs could serve as US triggered carriers of doxorubicin as well as tumor imaging agents in cancer therapy.

Remote loading of doxorubicin into liposomes by transmembrane pH gradient to reduce toxicity toward H9c2 cells

The use of doxorubicin (DOX) is limited by its dose-dependent cardiotoxicity. Entrapped DOX in liposome has been shown to reduce cardiotoxicity. Results showed that about 92% of the total drug was encapsulated in liposome. The release experiments showed a weak DOX leakage in both culture medium and in PBS, more than 98% and 90% of the encapsulated DOX respectively was still retained in liposomes after 24 h of incubation. When the release experiments were carried out in phosphate buffer pH5.3, the leakage of DOX from liposomes reached 37% after 24 h of incubation. Evaluation of cellular uptake of the liposomal DOX indicated the possible endocytosis of liposomes because the majority of visible fluorescence of DOX was mainly in the cytoplasm, whereas the nuclear compartment showed a weak intensity. When using unloaded fluorescent-liposomes, the fluorescence was absent in nuclei suggests that liposomes cannot cross the nuclear membrane. MTT assay and measurement of LDH release suggest that necrosis is the form of cellular death predominates in H9c2 cells exposed to high doses of DOX, while for weak doses apoptosis could be the predominate form. Entrapped DOX reduced significantly DOX toxicity after 3 and 6 h of incubation, but after 20 h entrapped DOX is more toxic than free one.

An improved D-α-tocopherol-based nanocarrier for targeted delivery of doxorubicin with reversal of multidrug resistance

Nanocarriers have recently emerged as an attractive platform for the delivery of various types of therapeutics including anticancer agents. Previously, we developed an improved TPGS delivery system (PEG5K-VE2) which demonstrated improved colloidal stability and greater in vivo antitumor activity. Nevertheless, the application of this system is still limited by a relatively low drug loading capacity (DLC). In this study we report that incorporation of a fluorenylmethyloxycarbonyl (Fmoc) motif at the interfacial region of PEG5K-VE2 led to significant improvement of the system through the introduction of an additional mechanism of drug/carrier interaction. Doxorubicin (DOX) could be effectively loaded into PEG5K-Fmoc-VE2 micelles at a DLC of 39.9%, which compares favorably to most reported DOX nanoformulations. In addition, PEG5K-Fmoc-VE2/DOX mixed micelles showed more sustained release of DOX in comparison to the counterpart without Fmoc motif. MTT assay showed that PEG5K-Fmoc-VE2/DOX exerted significantly higher levels of cytotoxicity over DOX, Doxil as well as PEG5K-VE2/DOX in PC-3 and 4T1.2 cells. A cytotoxicity assay with NCI/ADR-RES, a drug resistant cell line, suggested that PEG5K-Fmoc-VE2 may have the potential to reverse multidrug resistance, which was supported by its inhibition of P-gp ATPase. Pharmacokinetic (PK) and biodistribution studies showed an increased half-life in blood circulation and more effective tumor accuulation for DOX formulated in PEG5K-Fmoc-VE2 micelles. More importantly, DOX-loaded PEG5K-Fmoc-VE2 micelles showed an excellent safety profile with a MTD (~30 mgDOX/kg) that is about 3 times as much as that for free DOX. Finally, superior antitumor activity was demonstrated by PEG5K-Fmoc-VE2/DOX in both drug-sensitive (4T1.2 and PC-3) and drug-resistant (KB 8-5) tumor models compared to DOX, Doxil, and PEG5K-VE2/DOX.

Co-delivery of all-trans-retinoic acid and doxorubicin for cancer therapy with synergistic inhibition of cancer stem cells

Combination treatment through simultaneous delivery of two or more drugs with nanoparticles has been demonstrated to be an elegant and efficient approach for cancer therapy. Herein, we employ a combination therapy for eliminating both the bulk tumor cells and the rare cancer stem cells (CSCs) that have a high self-renewal capacity and play a critical role in cancer treatment failure. All-trans-retinoic acid (ATRA), a powerful differentiation agent of cancer stem cells and the clinically widely used chemotherapy agent doxorubicin (DOX) are simultaneously encapsulated in the same nanoparticle by a single emulsion method. It is demonstrated that ATRA and DOX simultaneous delivery-based therapy can efficiently deliver the drugs to both non-CSCs and CSCs to differentiate and kill the cancer cells. Differentiation of CSCs into non-CSCs can reduce their self-renewal capacity and increase their sensitivity to chemotherapy; with the combined therapy, a significantly improved anti-cancer effect is demonstrated. Administration of this combinational drug delivery system can markedly augment the enrichment of drugs both in tumor tissues and cancer stem cells, prodigiously enhancing the suppression of tumor growth while reduce the incidence of CSC in a synergistic manner.