Tat peptide and hexadecylphosphocholine introduction into pegylated liposomal doxorubicin: An in vitro and in vivo study on drug cellular delivery, release, biodistribution and antitumor activity

The effect of m2 peptide targeted nanoliposomes containing crocin on induction of phenotypic change in tumor macrophages to M1 state

AIMS

Crocin has immunomodulatory and anticancer effects. In this study, crocin was used to induce the M1 phenotype in mouse tumor macrophages.

MAIN METHODS

A targeted liposomal formulation with m2 peptide was prepared and characterized to deliver crocin to the M2 macrophages present in the tumor environment. RT-qPCR and IHC were performed for in vitro and in vivo (in C26 colon carcinoma mouse model at a dose of 50 mg/kg) assessment of M1 induction, respectively.

KEY FINDINGS

In vitro results indicated that liposome modified with m2 peptide was non-toxic to macrophages and had an improved uptake by macrophages compared to the non-targeted formulation and induced M1 phenotype through an IL6-independent pathway. M2 peptide- modified liposome showed considerable tumor accumulation and anti-tumor effects and significantly shifted the phenotype of tumor macrophages towards an anti-tumor M1 phenotype.

SIGNIFICANCE

Probably the remarkable anti-tumor responses observed in this study with m2 peptide-targeted liposomal formulations containing crocin were due to the enhanced delivery of crocin to the tumor macrophage and the subsequent initiation of anti-tumor immune responses.

Recent Preclinical and Clinical Progress in Liposomal Doxorubicin

Doxorubicin (DOX) is a potent anti-cancer agent that has garnered great interest in research due to its high efficacy despite dose-limiting toxicities. Several strategies have been exploited to enhance the efficacy and safety profile of DOX. Liposomes are the most established approach. Despite the improvement in safety properties of liposomal encapsulated DOX (in Doxil and Myocet), the efficacy is not superior to conventional DOX. Functionalized (targeted) liposomes present a more effective system to deliver DOX to the tumor. Moreover, encapsulation of DOX in pH-sensitive liposomes (PSLs) or thermo-sensitive liposomes (TSLs) combined with local heating has improved DOX accumulation in the tumor. Lyso-thermosensitive liposomal DOX (LTLD), MM-302, and C225-immunoliposomal(IL)-DOX have reached clinical trials. Further functionalized PEGylated liposomal DOX (PLD), TSLs, and PSLs have been developed and evaluated in preclinical models. Most of these formulations improved the anti-tumor activity compared to the currently available liposomal DOX. However, the fast clearance, the optimization of ligand density, stability, and release rate need more investigations. Therefore, we reviewed the latest approaches applied to deliver DOX more efficiently to the tumor, preserving the benefits obtained from FDA-approved liposomes.

Therapeutic silencing of mTOR by systemically administered siRNA-loaded neutral liposomal nanoparticles inhibits DMBA-induced mammary carcinogenesis

BACKGROUND

Mammary carcinogenesis possesses great challenges due to the lack of effectiveness of the multiple therapeutic options available. Gene therapy-based cancer treatment strategy provides more targeting accuracy, fewer side effects, and higher therapeutic efficiency. Downregulation of the oncogene mTOR by mTOR-siRNA is an encouraging approach to reduce cancer progression. However, its employment as means of therapeutic strategy has been restricted due to the unavailability of a suitable delivery system.

METHODS

A suitable nanocarrier system made up of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) has been developed to prevent degradation and for proficient delivery of siRNA. This was followed by in vitro and in vivo anti-breast cancer efficiency analysis of the mTOR siRNA-loaded neutral liposomal formulation (NL-mTOR-siRNA).

RESULTS

In our experiment, a profound reduction in MCF-7 cell growth, proliferation and invasion was ascertained following extensive downregulation of mTOR expression. NL-mTOR-siRNA suppressed tumour growth and restored morphological alterations of DMBA-induced breast cancer. In addition, neutral liposome enhanced accumulation of siRNA in mammary cancer tissues facilitating its deep cytosolic distribution within the tumour, which allows apoptosis thereby facilitating its anti-tumour potential.

CONCLUSION

Hence, the current study highlighted the augmented ground for therapies aiming toward cancerous cells to diminish mTOR expression by RNAi in managing mammary carcinoma.

Antennapedia-derived positively-charged peptide faces multiple problems upon their usage as targeting ligand for liposomal doxorubicin

The positively-charged peptide antp derived from Antennapedia transcription protein is demonstrated to mediate the liposome translocation across the cell membrane. In the current investigation, we prepared a stable liposomal doxorubicin (Dox) formulation and targeted it with the antp peptide from 0 to 200 ligand/liposome. These antp-containing liposomes were investigated in terms of physical stability on storage in the refrigerator and upon incubation in blood. Also, other features like cell binding, uptake, biodistribution, and treatment efficiency were evaluated in C26 colon carcinoma BALB/c mice. The Antp in liposomes resulted in enhanced particle growth with the development of the enormously large liposomes from 2000 to 6000 nm. Upon incubation in blood, these large liposomes were removed. The antp also enhanced the cell binding affinity and cell uptake rate of the liposomes and resulted in the restriction of the cancer cell proliferation, but it failed to improve the chemotherapeutic property of the Dox-liposome. The i.v. injection of antp-liposomes (15 mg Dox/kg) caused severe body weight loss and early death incidence due to probably increased toxicity. The antp targeting offered no advantage to the Dox-liposome in the delivery of Dox to the tumor, and failed to enhance the treatment efficiency of the liposomes.

pH-Sensitive PEGylated Liposomal Silybin: Synthesis, In Vitro and In Vivo Anti-Tumor Evaluation

The drug delivery systems improve the efficacy of chemotherapeutics through enhanced targeting and controlled release however, biological barriers of tumor microenvironment greatly impede the penetration of nanomedicine within the tumor. We report herein the fabrication of a PEG-detachable silybin (SLB) pH-sensitive liposome decorated with TAT-peptide. For this, Acyl hydrazide-activated PEG₂₀₀₀ was prepared and linked with ketone-derivatized DPPE via an acid-labile hydrazone bond to form mPEG₂₀₀₀-HZ-DPPE. TAT peptide was conjugated with a shorter -PEG₁₀₀₀-DSPE spacer and post-inserted into PEGylated liposome (DPPC: mPEG₂₀₀₀-DSPE: Chol). To prepare nanoliposomes (around 100 nm), first, a novel method was used to prepare SLB-Soya PC (SLB-SPC) complex, then this complex was incorporated into nanoliposomes. The pH-sensitivity and shielding effect of long PEG chain on TAT peptide was investigated using DiI liposome and FACS analysis. Pre-treatment to the lowered pH enhanced cellular association of TAT-modified pH-sensitive liposome due to the cleavage of hydrazone bond and TAT exposure. Besides, TAT-modified pH-sensitive liposomes significantly reduced cell viability compared to the plain liposome. In vivo results were very promising with pH-sensitive liposome by detaching PEG moieties upon exposure to the acidic tumor microenvironment, enhancing cellular uptake, retarding tumor growth, and prolonging the survival of 4T1 breast tumor-bearing BALB/c mice. TAT modification of pH-sensitive liposome improved cancer cell association and cytotoxicity and demonstrated potential intracellular delivery upon exposure to acidic pH. However, in in vivo studies, TAT as a targeting ligand significantly decreased the therapeutic efficacy of the formulation attributed to an inefficient tumor accumulation and higher release rate in the circulation. The results of this study indicated that pH-sensitive liposome containing SLB, which was prepared with a novel method with a significant SLB loading efficiency, is very effective in the treatment of 4T1 breast tumor-bearing BALB/c mice and merits further investigation.

Integrin α2β1 Targeting DGEA-Modified Liposomal Doxorubicin Enhances Antitumor Efficacy against Breast Cancer

Breast cancer was the leading cause of newly diagnosed cases of tumors in 2020, ranking as the second highest cause of female death. Chemotherapy remains the conventional treatment of choice for breast tumors in most clinical cases. However, it is often accompanied by a poor prognosis and severe side effects, resulting from an insufficient accumulation of the drug at tumor sites and an unsystematic distribution of the drug across the body. Inspired by the fact that breast tumor cells overexpress integrin α2β1 on the surface, we designed and constructed an integrin α2β1 targeting DGEA-modified liposomal doxorubicin (DGEA-Lipo-DOX) platform for application in breast cancer therapy. The DGEA-Lipo-DOX was stable with a uniform particle size of 121.1 ± 3.8 nm and satisfactory drug encapsulation. Demonstrated in vitro and in vivo, the constructed platform exhibited improved antitumor ability. The DGEA-Lipo-DOX showed 4-fold enhanced blood circulation and 6-fold increased accumulation of DOX at the tumor sites compared to those of free DOX, resulting in a significantly enhanced antitumor efficacy in tumor-bearing mice. A preliminary safety evaluation suggested that the systemic toxicity of DOX was relieved by DGEA-Lipo delivery. Collectively, binding integrin α2β1 by DGEA may represent an alternative therapeutic strategy for potentially safer breast cancer treatment.

Improving anti-tumour efficacy of PEGylated liposomal doxorubicin by dual targeting of tumour cells and tumour endothelial cells using anti-p32 CGKRK peptide

The aim of this study was to surface-functionalize PEGylated liposomal doxorubicin (PLD) using anti-p32 CGKRK peptide to evaluate its anti-angiogenic and anti-tumour activities. CGKRK was conjugated to DSPE-mPEG₂₀₀₀-maleimide and post-inserted into PLD at 25, 50, 100, 200 and 400 peptides per each liposome and characterised for their size, zeta potential, drug loading, release properties; and cell binding, cell uptake and cytotoxicity on three C26, 4T1 and human umbilical vein endothelial cell (HUVEC) cell lines. The in vitro results indicated the better efficiency of the PLD-100 (PLD with 100 CGKRK) formulation on 4T1 and HUVEC cell lines. The results of anti-tube formation and spheroid assay indicated the efficiencies of the PLD-100 formulation compared with Caelyx^® in vitro. The in vivo studies indicated the higher tumour accumulation of PLD-100 formulation in comparison with Caelyx^® which also implied the higher survival rates in mice treated with PLD-100 formulation. Histological evaluations demonstrated that PLD-100 had no side-effects on major organs. In conclusion, the results of this study indicated that PLD-CGKRK- could efficiently target endothelial and tumour parenchymal cells which enhance the therapeutic efficacy of PLD and merits further investigation.

PEGylation and Cell-Penetrating Peptides: Glimpse into the Past and Prospects in the Future

Several drug molecules have shown low bioavailability and pharmacokinetic profile due to metabolism by enzymes, excretion by the renal system, or due to other physiochemical properties of drug molecules. These problems have resulted in the loss of efficacy and the gain of side effects associated with drug molecules. PEGylation is one of the strategies to overcome these pharmacokinetic issues and has been successful in the clinic. Cell-penetrating Peptides (CPPs) help to deliver molecules across biological membranes and could be used to deliver cargo selectively to the intracellular site or to the drug target. Hence CPPs could be used to improve the efficacy and selectivity of the drug. However, due to the peptidic nature of CPPs, they have a low pharmacokinetic profile. Using PEGylation and CPPs together as a component of a drug delivery system, the and efficacy of drug molecules could be improved. The other important pharmacokinetic properties such as short half-life, solubility, stability, absorption, metabolism, and elimination could be also improved. Here in this review, we summarized PEGylated CPPs or PEGylation based formulations for CPPs used in a drug delivery system for several biomedical applications until August 2019.

The trip of a drug inside the body: From a lipid-based nanocarrier to a target cell

To date, enormous investigations have been conducted to enhance medicines' target-oriented delivery to improve their therapeutic index. In this regard, lipid-based carrier system might have been regarded as prime delivery systems that are very close to the naturally cell-derived vesicles used for biomolecular communication among cells from occasionally remote tissues. Upon examination of the literature, we found a chasm between groups of investigations in drug pharmaceutics and thought that maybe holistic research could provide better information with respect to drug delivery inside the body, especially when they are going to be injected directly into the bloodstream for systemic distribution. While a collection of older research in most cases dealt with the determination of drug partition coefficient between the aqueous and cell membrane compartments, the link has been overlooked in newer investigations that were mostly focused on drug formulation optimization and their association with particle biodistribution. This gap in the literature motivated us to present the current opinion paper, in which drug physicochemical properties like drug lipophilicity/hydrophilicity is considered as an important element in designing drug-carrying liposomes or micelles. How a hypothetical high throughput cell-embedded chromatographic technique might help to investigate a nanocarrier tissue distribution and to design 'multi-epitope grafted lipid-based drug carrier systems' are discussed. Whenever we would need support for our opinions, we have provided analogy from hydrophobic biomolecules like cholesterol, steroid hormones, and sex hormones and encouraged readers to consider our principle hypothesis: If these molecules could reach their targets far away from the site of production, then a large list of hydrophobic drugs could be delivered to their targets using the same principles.

Liposomal formulation of Galbanic acid improved therapeutic efficacy of pegylated liposomal Doxorubicin in mouse colon carcinoma

Galbanic acid (Gba), a sesquiterpene coumarin, with strong antiangiogenic activity could serve as an excellent anti-cancer agent. However, Gba is a poor water-solube which hampered its clinical application. In this study, a pegylated liposomal Gba (PLGba) with HSPC/Cholesterol/mPEG2000-DSPE (56.2, 38.3, 5.3% molar ratio) was developed by the thin film hydration plus extrusion and calcium acetate gradient remote loading method, to address the issue of poor Gba solubility. Moreover, an integrin-targeting ligand (RGD peptide, cyclo[Arg-Gly-Asp-D-Tyr-Cys]) was post-inserted into liposomes in order to increase Gba cell delivery. Using fluorescently-labeled model liposomes, it was found that the targeting could improve the integrin-mediated cellular uptake of the liposomes in vitro in human umbilical vein endothelial cells (HUVECs), and in vivo as evidenced by chicken chorioallantoic membrane angiogenesis (CAM) model. It also could enrich the liposome accumulation in C26 tumor. Interestingly, co-treatment with PLGba and pegylated liposomal doxorubicin (PLD, also known as Doxil®) had a synergistic and antagonistic antiproliferative effect on the C26 tumor cell line and the normal HUVEC, respectively. In C26 tumor bearing BALB/c mice, the PLGba and PLD combinatorial therapy improved the antitumor efficacy of the treatment as compared to those of single agents. This results have clear implications for cancer therapy.

Niosome-loaded antifungal drugs as an effective nanocarrier system: A mini review

Skin is an important organ of the body due to offering an accessible and convenient site for drug administration. One of the disadvantages of transdermal drug delivery is the low penetration rate of drugs through the skin. Over the past decades, nanoparticles have been used as drug delivery systems to increase therapeutic effects or reduce toxicity. Encapsulation of drugs in nanoparticulate vesicles simplifies the transports of drugs into and across the skin.

Niosome nanoparticles are among these drug delivery systems, which have numerous applications in drug delivery and targeting. Niosomes are frequently used for loading drugs serving different purposes (e.g., anticancer, antiviral, and antibacterial agents). In recent years, there has been much research on the use of niosomal systems for the delivery of fungal drugs. A review of the literature investigating the advantages of niosomes in antifungal drug delivery can elucidate the efficiency and superiority of this nanocarrier over other nanocarriers.

Liposomal CpG-ODN: An in vitro and in vivo study on macrophage subtypes responses, biodistribution and subsequent therapeutic efficacy in mice models of cancers

CpG oligodeoxynucleotides (CpG-ODN), a common immune stimulator and vaccine adjuvant, was reported to switch Tumor Associated Macrophages (TAMs) from M2 to M1 phenotype inducing anti-tumor responses. Liposomes are of the successfully applied carriers for CpG-ODN. The aim of present study was design and preparation of a liposomal formulation containing phosphodiester CpG-ODN, evaluation of its effect on macrophages responses, and subsequent antitumor responses in mice. Liposomal formulations containing phosphodiester CpG-ODN or non-CpG-ODN were prepared and characterized. MTT reduction assay in four different cell lines, uptake, arginase and iNOS activity evaluation in macrophage cell lines, biodistribution study and therapeutic anti-tumor effects of formulations in mice bearing C26 colon carcinoma or B16F0 melanoma were carried out. The size of liposomes containing CpG-ODN was ~200 nm with the encapsulation efficiency of 33%. The iNOS activity assay showed high nitric oxide (NO) level in M2 phenotype of macrophage cell lines treated by liposomes containing CpG-ODN. In mice which received liposomes containing CpG-ODN as a monotherapy, maximum tumor growth delay with remarkable survival improvement was observed compared to control groups. Biodistribution study showed the accumulation of liposomal formulation in tumor micro-environment. In conclusion, considerable anti-tumor responses observed by liposomes containing CpG-ODN was due to enhanced delivery of CpG-ODN to immune cells and subsequent initiation of anti-tumoral immune responses.

Combination of doxorubicin with harmine-loaded liposomes exerting synergistic antitumor efficacy

CONTEXT

Long-circulation (PEGLip), pH-sensitive (PEOzLip), and active targeted liposomes (PEG-TATLip)-loading doxorubicin (DOX) and harmine (HM) were prepared. Their physicochemical properties and antitumor effect were investigated.

OBJECTIVES

The aims of the present study were to evaluate synergistic antitumor efficacy.

MATERIALS AND METHODS

Liposomes were prepared by using thin-film dispersion, active drug-loading and target post-insertion method. Subsequently physiochemical properties including particle size distribution, zeta potential, entrapment efficiency (EE), drug-loading content and in-vitro release were determined. Besides, the in vitro cytotoxicity of free drugs and drug-loaded liposomes was explored by using a Sulforhodamine-B Staining assay and the combination index values (CI Value) were calculated. Finally, the cellular uptake experiments by MCF-7cells were carried out via flow cytometry.

RESULTS AND DISCUSSION

All liposomes enhanced the antitumor effect significantly compared to free drugs. Among liposomes, PEG-TATLip enhanced the antitumor effect significantly compared to others. DOX and HM had moderate synergism with CI Value 0.85 for free drugs, 0.81 for PEGLip, 0.72 for PEOzLip, and 0.84 for PEG-TATLip respectively when the weight ratio of two drugs was 1:2. Moreover, the similarity between DOX and HM such as physicochemical properties, in vitro release modes and in vitro uptake kinetics characteristics when they were in the same formulations proved it possible for them to be delivered together.

CONCLUSION

Active targeting liposomes were the most effective delivery system as compared with pH-sensitive and long circulation liposomes. Additionally, DOX and HM could be co-delivered in liposomes and they could play moderate synergism effect in antitumor efficacy.

TAT-modified self-assembled cationic peptide nanoparticles as an efficient antibacterial agent

The increasing emergence of drug resistant pathogenic bacteria poses a great challenge to clinical therapy and a threat to public health. Cationic peptides have received great attention for their unique antibacterial mechanism and ability to combat drug-resistant bacteria. In this study, we designed a TAT-modified cationic peptide PA-28 which self-assembled into nanoparticles of about 150 nm. These nanoparticles showed strong antimicrobial activities against both gram-positive and gram-negative bacteria, including drug-resistant bacteria. They were more potent than the unassembled counterpart peptide nonalysine (K₉). Their antibacterial mechanism of directly destructing bacterial wall/membrane reduces the possibility of developing bacterial resistance. In vivo anti-infective experiments showed that these nanoparticles were able to penetrate the blood-brain barrier to inhibit bacterial growth in infected brains of rats. In addition, these nanoparticles induced low hemolysis below the minimum inhibitory concentration. Therefore, the peptide designed in this study is a promising and efficient antibacterial agent against bacterial infections.

Biological and pharmacological evaluation of dimethoxycurcumin: A metabolically stable curcumin analogue with a promising therapeutic potential

Dimethoxycurcumin (DiMC) is a synthetic analog of curcumin with superior inter-related pro-oxidant and anti-cancer activity, and metabolic stability. Numerous studies have shown that DiMC reserves the biologically beneficial features, including anti-inflammatory, anti-carcinogenic, and cytoprotective properties, almost to the same extent as curcumin exhibits. DiMC lacks the phenolic-OH groups as opposed to curcumin, dimethoxycurcumin, and bis-demethoxycurcumin that all vary in the number of methoxy groups per molecule, and has drawn the attentions of researchers who attempted to discover the structure-activity relationship (SAR) of curcumin. In this regard, tetrahydrocurcumin (THC), the reduced and biologically inert metabolite of curcumin, denotes the significance of the conjugated α,β diketone moiety for the curcumin activity. DiMC exerts unique molecular activities compared to curcumin, including induction of androgen receptor (AR) degradation and suppression of the transcription factor activator protein-1 (AP-1). The enhanced AR degradation on DiMC treatment suggests it as a novel anticancer agent against resistant tumors with androgenic etiology. Further, DiMC might be a potential treatment for acne vulgaris. DiMC induces epigenetic alteration more effectively than curcumin, although both showed no direct DNA hypomethylating activity. Given the metabolic stability, nanoparticulation of DiMC is more promising for in vivo effectiveness. However, studies in this regard are still in its infancy. In the current review, we portray the various molecular and biological functions of DiMC reported so far. Whenever possible, the efficiency is compared with curcumin and the reasons for DiMC being more metabolically stable are elaborated. We also provide future perspective investigations with respect to varying DiMC-nanoparticles.

One-pot synthesis of pH-responsive hyperbranched polymer–peptide conjugates with enhanced stability and loading efficiency for combined cancer therapy

Nanoparticles as drug-delivery systems have received significant attention due to their merits such as prolonged circulation time and passive targeting of a tumor site.

Peptide-Based Ligand for Active Delivery of Liposomal Doxorubicin

Doxorubicin (DOX) has been extensively used in the clinic to treat malignant tumors such as leukemias and Hodgkin’s lymphoma. However, the severe cardiotoxicity associated with the use of DOX requests the development of alternative and efficient pharmaceutical formulations. The PEGylated liposome of DOX can significantly reduce the cardiotoxicity but still lacks the active targeting towards cancer cells. Modification of liposomal DOX with active ligands would then be a rational approach to enhance the transportation of the toxin into tumor cells. Currently used targeting ligands include antibodies, proteins, small molecules, and peptides. By virtue of the advantages such as easy preparation, lower cost, and elevated resistance to enzymatic degradation, peptides are attracting a significant amount of interest as active targeting ligands for pharmaceutics. In this paper, we will briefly discuss the application of peptide ligands for the improvement of the therapeutic efficacy of liposomal DOX.