Targeted delivery of small interfering RNA using reconstituted high-density lipoprotein nanoparticles

Scavenger Receptor Class B Type 1 (SR-B1) being a Potential Biomarker for the Diagnosis of Liposarcoma and Associated with the Degree of Differentiation of Liposarcomas

Background: Soft tissue sarcomas include multiple histological subtypes and are highly aggressive. Moreover, SR-B1 is associated with malignant behavior and poor prognosis in a variety of cancers. However, there have been no attempts to assess whether SR-B1 expression in soft tissue sarcoma. We aimed to detect the expression levels of the SR-B1 protein in soft tissue sarcoma.

Methods: We assessed SR-B1 expression via immunohistochemistry and tissue microarrays in 107 soft tissue sarcomas with 4 phenotypes: 26 liposarcomas, 18 Ewing's sarcomas, 20 rhabdomyosarcomas and 43 leiomyosarcomas.

Results: Tumor cell SR-B1 expression was seen in 18/26 (69.2%) liposarcomas, 1/18 (5.55%) Ewing's sarcomas, 1/20 (5.00%) rhabdomyosarcomas, 2/43 (4.70%) leiomyosarcomas and was stained in the cell membrane. We found that SR-B1 expression in liposarcomas (18/26) was significantly higher than that in non-lipomatous sarcomas (4/77) (χ2 = 49.811, p = 0.000) and in well-differentiated liposarcoma (13/15) was significantly higher than that in dedifferentiated liposarcoma (5/11) (p = 0.038). No significant correlation was found between SR-B1 and gender, nationality, size and tumor location (p > 0.05), but it was significantly associated with ages (χ2 = 11.426, p = 0.001) and sarcoma phenotypes (χ2 = 49.817, p = 0.000).

Conclusion: Our findings highlight the highly expression of SR-B1 in liposarcomas. SR-B1 may be a potential biomarker for the diagnosis of liposarcoma and may indicate the degree of differentiation of liposarcomas.

The role of high-density lipoproteins in antitumor drug delivery

High-density lipoproteins (HDLs) are the smallest lipoprotein with the highest level of protein in their surface. The main role of HDLs are reverse transport of cholesterol from peripheral tissues to the liver. More recently, HDLs have been considered as a new drug delivery system because of their small size, proper surface properties, long circulation time, biocompatibility, biodegradability, and low immune stimulation. Delivery of anticancer drug to the tumor tissue is a major obstacle against successful chemotherapy, which is because of the toxicity and poor aqueous solubility of these drugs. Loading chemotherapeutic drugs in the lipid core of HDLs can overcome the aforementioned problems and increase the efficiency of drug delivery. In this review, we discuss the use of HDLs particles in drug delivery to the tumor tissue and explain some barriers and limitations that exist in the use of HDLs as an ideal delivery vehicle.

Identifying and targeting angiogenesis-related microRNAs in ovarian cancer

Current anti-angiogenic therapy for cancer is based mainly on inhibition of the vascular endothelial growth factor pathway. However, due to the transient and only modest benefit from such therapy, additional approaches are needed. Deregulation of microRNAs (miRNAs) has been demonstrated to be involved in tumor angiogenesis and offers opportunities for a new therapeutic approach. However, effective miRNA-delivery systems are needed for such approaches to be successful. In this study, miRNA profiling of patient data sets, along with in vitro and in vivo experiments, revealed that miR-204-5p could promote angiogenesis in ovarian tumors through THBS1. By binding with scavenger receptor class B type 1 (SCARB1), reconstituted high-density lipoprotein-nanoparticles (rHDL-NPs) were effective in delivering miR-204-5p inhibitor (miR-204-5p-inh) to tumor sites to suppress tumor growth. These results offer a new understanding of miR-204-5p in regulating tumor angiogenesis.

Role of cholesterol homeostasis and its efflux pathways in cancer progression

Tumor cells show high avidity for cholesterol in order to support their inherent nature to divide and proliferate. This results in the rewiring of cholesterol homeostatic pathways by influencing not only de novo synthesis but also uptake or efflux pathways of cholesterol. Recent findings have pointed towards the importance of cholesterol efflux in tumor pathogenesis. Cholesterol efflux is the first and foremost step in reverse cholesterol transport and any perturbation in this pathway may lead to the accumulation of intracellular cholesterol, thereby altering the cellular equilibrium. This review addresses the different mechanisms of cholesterol efflux from the cell and highlights their role and regulation in context to tumor development. There are four different routes by which cholesterol can be effluxed from the cell namely, 1) passive diffusion of cholesterol to mature HDL particles, 2) SR-B1 mediated facilitated diffusion, 3) Active efflux to apo A1 via ABCA1 and 4) ABCG1 mediated efflux to mature HDL. These molecular players facilitating cholesterol efflux are engaged in a complex interplay with different signaling pathways. Thus, an understanding of the efflux pathways, their regulation and cross-talk with signaling molecules may provide novel prognostic markers and therapeutic targets to combat the onset of carcinogenesis.

Clinical relevance of cholesterol homeostasis genes in colorectal cancer

Accumulation of cholesterol is a well-known feature in cancer. Preclinical studies suggest the contribution of various cholesterol regulators in CRC. However, their clinical relevance remains poorly understood. The aim of the present study is to evaluate the expression of these modulators in CRC and elucidate their diagnostic and prognostic value. mRNA levels of HMGCR, SREBF2, NR1H3 and NR1H2 were downregulated in tumors in local and TCGA cohort. The expression of LDLR, ABCA1 and SCARB1 was not consistent in the two cohorts. Western Blot analysis showed the increased levels of LDLR and reduced levels of LXR in early stage patients. Tumoral SREBP2 levels were enhanced in early stage whereas decreased in late stage. The individual expression of HMGCR, SREBF2, NR1H3 and NR1H2 did not have the potential to be used as independent prognostic marker, however, the combined expression of these genes associated with poor clinical outcome independent of lymph node metastasis, distant metastasis and advanced stage. This work sheds light on deregulation of cholesterol uptake and efflux pathways and provides novel leads in the development of biomarkers and therapeutic regimens that can detect and target CRC at initial stages.

The SR-B1 Receptor as a Potential Target for Treating Glioblastoma

Purpose

The goal of these studies was to provide proof of concept for a novel targeted therapy for Glioblastoma Multiforme (GBM). Methods. These studies involve the evaluation of reconstituted high density lipoprotein (rHDL) nanoparticles (NPs) as delivery agents for the drug, mammalian Target of Rapamycin (mTOR) inhibitor Everolimus (EVR) to GBM cells. Cytotoxicity studies and assessment of downstream effects, including apoptosis, migration, and cell cycle events, were probed, in relation to the expression of scavenger receptor B type 1 (SR-B1) by GBM cells.

Results

Findings from cytotoxicity studies indicate that the rHDL/EVR formulation was 185 times more potent than free EVR against high SR-B1 expressing cell line (LN 229). Cell cycle analysis revealed that rHDL/EVR treated LN229 cells had a 5.8 times higher apoptotic cell population than those treated with EVR. The sensitivity of GBM cells to EVR treatment was strongly correlated with SR-B1 expression.

Conclusions

These studies present strong proof of concept regarding the efficacy of delivering EVR and likely other agents, via a biocompatible transport system, targeted to the SR-B1 receptor that is upregulated in most cancers, including GBM. Targeting the SR-B1 receptor could thus lead to effective personalized therapy of GBM.

Peptide-mediated delivery of therapeutic mRNA in ovarian cancer

Ovarian cancer is the most lethal gynecological malignancy in the developed world. In spite of intensive research, the mortality has hardly decreased over the past twenty years. This necessitates the exploration of novel therapeutic modalities. Transient protein expression through delivery of mRNA is emerging as a highly promising option. In contrast to gene therapy there is no risk of integration into the genome. Here, we explore the expression of mRNA in models of ovarian cancer of increasing complexity. The cell-penetrating peptide (CPP) PepFect 14 (PF14) was used to formulate CPP-mRNA nanoparticles. Efficient expression of a reporter protein was achieved in two-dimensional tissue cultures and in three-dimensional cancer cell spheroids. PF14 nanoparticles greatly outperformed a lipid-based transfection agent in vivo, leading to expression in various cell types of tumor associated tissue. Protein expression was restricted to the peritoneal cavity. Messenger RNA expression across different cell types was confirmed in primary ovarian cancer explants. As ovarian cancer is confined to the peritoneal cavity in most cases, the results create the basis for applications in which the tumor microenvironment is transiently modified through protein expression.

A TRAIL-Delivered Lipoprotein-Bioinspired Nanovector Engineering Stem Cell-Based Platform for Inhibition of Lung Metastasis of Melanoma

Genetically engineered mesenchymal stem cells (MSCs), as non-viral gene delivery platforms, are rapidly evolving in tumor therapy due to their low immunogenicity and natural tumor-homing capacity. Methods: In this paper, we selected reconstituted high-density lipoprotein (rHDL), a lipoprotein-bioinspired nanovector with specific binding ability to scavenger receptor B type I (SR-BI) expressed on MSCs, as a transfection agent to genetically modify MSCs. pDNA encoding tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) was used as a functional gene to be transfected into the nucleus of MSCs for TRAIL expression. Lauric acid-coupled polyethyleneimine (PEI-LA) as an amphiphilic cationic polymer was synthesized to electrostatically bind to pDNA, and then incorporated into rHDL to form rHDL/PEI-LA/pDNA nanoparticles. Results: The nanoparticles exhibited homogenous particle size and excellent serum stability in vitro. Meanwhile, this SR-BI-targeted rHDL performed efficient intracellular gene delivery, specific lysosome-independent mechanism of cellular uptake and high transfection of pDNA towards MSCs. Moreover, high TRAIL expression in MSCs was detected after rHDL-mediated transfection. In vitro and in vivo results indicated that genetically engineered MSCs could accurately target to B16F10 cells, thereby producing significant apoptosis-inducing effect on aggressive melanoma. Conclusion: TRAIL-expressing MSCs engineered by rHDL nanovector was an efficient and hypotoxic method for stem cells-based pulmonary melanoma metastasis-targeting therapy.

Secretome of adipose-derived mesenchymal stem cells promotes skeletal muscle regeneration through synergistic action of extracellular vesicle cargo and soluble proteins

BACKGROUND

The mechanisms underpinning the regenerative capabilities of mesenchymal stem cells (MSC) were originally thought to reside in their ability to recognise damaged tissue and to differentiate into specific cell types that would replace defective cells. However, recent work has shown that molecules produced by MSCs (secretome), particularly those packaged in extracellular vesicles (EVs), rather than the cells themselves are responsible for tissue repair.

METHODS

Here we have produced a secretome from adipose-derived mesenchymal stem cells (ADSC) that is free of exogenous molecules by incubation within a saline solution. Various in vitro models were used to evaluate the effects of the secretome on cellular processes that promote tissue regeneration. A cardiotoxin-induced skeletal muscle injury model was used to test the regenerative effects of the whole secretome or isolated extracellular vesicle fraction in vivo. This was followed by bioinformatic analysis of the components of the protein and miRNA content of the secretome and finally compared to a secretome generated from a secondary stem cell source.

RESULTS

Here we have demonstrated that the secretome from adipose-derived mesenchymal stem cells shows robust effects on cellular processes that promote tissue regeneration. Furthermore, we show that the whole ADSC secretome is capable of enhancing the rate of skeletal muscle regeneration following acute damage. We assessed the efficacy of the total secretome compared with the extracellular vesicle fraction on a number of assays that inform on tissue regeneration and demonstrate that both fractions affect different aspects of the process in vitro and in vivo. Our in vitro, in vivo, and bioinformatic results show that factors that promote regeneration are distributed both within extracellular vesicles and the soluble fraction of the secretome.

CONCLUSIONS

Taken together, our study implies that extracellular vesicles and soluble molecules within ADSC secretome act in a synergistic manner to promote muscle generation.

RNA interference-based therapy and its delivery systems

RNA interference (RNAi) is considered a highly specific approach for gene silencing and holds tremendous potential for treatment of various pathologic conditions such as cardiovascular diseases, viral infections, and cancer. Although gene silencing approaches such as RNAi are widely used in preclinical models, the clinical application of RNAi is challenging primarily because of the difficulty in achieving successful systemic delivery. Effective delivery systems are essential to enable the full therapeutic potential of RNAi. An ideal nanocarrier not only addresses the challenges of delivering naked siRNA/miRNA, including its chemically unstable features, extracellular and intracellular barriers, and innate immune stimulation, but also offers "smart" targeted delivery. Over the past decade, great efforts have been undertaken to develop RNAi delivery systems that overcome these obstacles. This review presents an update on current progress in the therapeutic application of RNAi with a focus on cancer therapy and strategies for optimizing delivery systems, such as lipid-based nanoparticles.

Protein-based vehicles for biomimetic RNAi delivery

Broad translational success of RNA interference (RNAi) technology depends on the development of effective delivery approaches. To that end, researchers have developed a variety of strategies, including chemical modification of RNA, viral and non-viral transfection approaches, and incorporation with delivery vehicles such as polymer- and lipid-based nanoparticles, engineered and native proteins, extracellular vesicles (EVs), and others. Among these, EVs and protein-based vehicles stand out as biomimetically-inspired approaches, as both proteins (e.g. Apolipoprotein A-1, Argonaute 2, and Arc) and EVs mediate intercellular RNA transfer physiologically. Proteins specifically offer significant therapeutic potential due to their biophysical and biochemical properties as well as their ability to facilitate and tolerate manipulation; these characteristics have made proteins highly successful translational therapeutic molecules in the last two decades. This review covers engineered protein vehicles for RNAi delivery along with what is currently known about naturally-occurring extracellular RNA carriers towards uncovering design rules that will inform future engineering of protein-based vehicles.

Signal Transducer and Activator of Transcription (STATs) Proteins in Cancer and Inflammation: Functions and Therapeutic Implication

Signal Transducer and Activator of Transcription (STAT) pathway is connected upstream with Janus kinases (JAK) family protein and capable of integrating inputs from different signaling pathways. Each family member plays unique functions in signal transduction and crucial in mediating cellular responses to different kind of cytokines. STAT family members notably STAT3 and STAT5 have been involved in cancer progression whereas STAT1 plays opposite role by suppressing tumor growth. Persistent STAT3/5 activation is known to promote chronic inflammation, which increases susceptibility of healthy cells to carcinogenesis. Here, we review the role of STATs in cancers and inflammation while discussing current therapeutic implications in different cancers and test models, especially the delivery of STAT3/5 targeting siRNA using nanoparticulate delivery system.

siRNA-Conjugated Nanoparticles to Treat Ovarian Cancer

Ovarian cancer is the fifth-most lethal cancer among women due to a lack of early detection and late-stage treatment options, and it is responsible for more than 14,000 deaths each year in the United States. Recently, there have been advances in RNA interference therapy, specifically with small interfering RNA (siRNA), to reduce tumor burden for ovarian cancer via gene down-regulation. However, delivery of siRNA poses its own challenges, as siRNA is unstable in circulation, is unable to be effectively internalized by cells, and may cause toxicity in off-target sites. To address such challenges, nanoparticle carriers have emerged as delivery platforms for the biocompatible, targeted delivery of siRNA-based therapies. Several preclinical studies have shown the promising effects of siRNA therapy to reduce chemotherapy resistance and proliferation of ovarian cancer cells. This review evaluates the recent advances, clinical applications, and future potential of nanoparticle-mediated delivery of siRNA therapeutics to target genes implicated in ovarian cancer.

[99mTc-HYNIC-N-dodecylamide]: a new hydrophobic tracer for labelling reconstituted high-density lipoproteins (rHDL) for radioimaging

Despite the widespread use of nanotechnology in radio-imaging applications, lipoprotein based delivery systems have received only limited attention so far. These studies involve the synthesis of a novel hydrophobic radio-imaging tracer consisting of a hydrazinonicotinic acid (HYNIC)-N-dodecylamide and 99mTc conjugate that can be encapsulated into rHDL nanoparticles (NPs). These rHDL NPs can selectively target the Scavenger Receptor type B1 (SR-B1) that is overexpressed on most cancer cells due to excess demand for cholesterol for membrane biogenesis and thus can target tumors in vivo. We provide details of the tracer synthesis, characterization of the rHDL/tracer complex, in vitro uptake, stability studies and in vivo application of this new radio-imaging approach.

Targeting triple-negative breast cancer cells using Dengue virus-mimicking pH-responsive framboidal triblock copolymer vesicles

Dengue fever-mimicking pH-responsive framboidal triblock copolymer vesicles enable delivery of a nucleic acid payload to the nuclei of triple-negative breast cancer cells.

KIAA1199 promotes invasion and migration in non-small-cell lung cancer (NSCLC) via PI3K-Akt mediated EMT

KIAA1199 is often upregulated in cancer cells, including non-small-cell lung cancer (NSCLC). Although KIAA1199 is associated with aggressive tumor phenotype and poor survival in NSCLC, little is known about its functional role in NSCLC progression. Using archived clinical samples, we evaluated KIAA1199 messenger RNA (mRNA) and protein expression in NSCLC tissues and correlated with NSCLC clinicopathological characteristics as well as overall survival. Using NSCLC cell lines, KIAA1199 was either silenced using gene-specific shRNA or overexpressed to assess the impact on EMT signaling pathways. Finally, in a mouse xenograft NSCLC model, we determine the therapeutic potential of KIAA1199 repression. Our data showed that KIAA1199 was significantly upregulated in NSCLC tissues compared to adjacent normal tissues both at the mRNA (P < 0.001) and protein levels (P < 0.05). KIAA1199 overexpression is an independent prognostic marker for overall survival (HR = 1.833). In NSCLC cell lines, KIAA1199 expression directly influences the expression of EMT markers, EMT-inducing transcription factors (EMT-TFs), and EMT signaling molecules. Knocking down of KIAA1199 expression in the mouse NSCLC xenograft model significantly suppressed tumor growth and augmented the efficacy of chemotherapy (n = 5; P < 0.05). We conclude that KIAA1199 is not only a prognostic marker but a novel therapeutic target in NSCLC through regulating EMT signaling pathway. KEY MESSAGES: KIAA1199 overexpression is an independent prognostic marker in NSCLC. KIAA1199 expression directly influences the expression of EMT markers. KIAA1199 promotes invasion and migration in NSCLC via PI3K-Akt mediated EMT.

Reconstituted HDL: Drug Delivery Platform for Overcoming Biological Barriers to Cancer Therapy

Drug delivery to malignant tumors is limited by several factors, including off-target toxicities and suboptimal benefits to cancer patient. Major research efforts have been directed toward developing novel technologies involving nanoparticles (NPs) to overcome these challenges. Major obstacles, however, including, opsonization, transport across cancer cell membranes, multidrug-resistant proteins, and endosomal sequestration of the therapeutic agent continue to limit the efficiency of cancer chemotherapy. Lipoprotein-based drug delivery technology, "nature's drug delivery system," while exhibits highly desirable characteristics, it still needs substantial investment from private/government stakeholders to promote its eventual advance to the bedside. Consequently, this review focuses specifically on the synthetic (reconstituted) high-density lipoprotein rHDL NPs, evaluating their potential to overcome specific biological barriers and the challenges of translation toward clinical utilization and commercialization. This highly robust drug transport system provides site-specific, tumor-selective delivery of anti-cancer agents while reducing harmful off-target effects. Utilizing rHDL NPs for anti-cancer therapeutics and tumor imaging revolutionizes the future strategy for the management of a broad range of cancers and other diseases.

A dual-targeting reconstituted high density lipoprotein leveraging the synergy of sorafenib and antimiRNA21 for enhanced hepatocellular carcinoma therapy

Sorafenib (So) is a multi-target kinase inhibitor extensively used in clinic for hepatocellular carcinoma therapy. It demonstrated strong inhibition both in tumor proliferation and tumor angiogenesis, while hampered by associated cutaneous side-effect and drug resistance. The knockdown of miR-21 with antisense oligonucleotides (antimiRNA21) was regarded as an efficient strategy for increasing tumor sensibility to chemotherapy, which could be employed to appreciate the efficacy of So. Herein, we successfully formulated a dual-targeting delivery system for enhanced hepatocellular carcinoma therapy by encapsulating So and antimiRNA21 in RGD pentapeptide-modified reconstituted high-density lipoprotein (RGD-rHDL/So/antimiRNA21). The RGD and apolipoprotein A-I (ApoA-I) on nanoparticles (NPs) could drive the system simultaneously to tumor neovascular and parenchyma by binding to the overexpressed ανβ3-integrin and SR-B1 receptors, achieving precise delivery of therapeutics to maximize the efficacy. A series in vitro and in vivo experiments revealed that co-delivery of So and antimiRNA21 by RGD-rHDL significantly strengthened the anti-tumor and anti-angiogenic effect of So with negligible toxicity towards major organs, reversed drug-resistance and was capable of remodeling tumor environments. The constructed RGD-rHDL/So/antimiRNA21 with improved efficacy and excellent tumor targeting ability provided new idea for chemo-gene combined therapy in hepatocellular carcinoma.

STATEMENT OF SIGNIFICANCE

Sorafenib (So) is a multi-target kinase inhibitor which was approved by FDA as first-line drug for hepatocellular carcinoma (HCC) therapy. However, long term application of So in clinic was hampered by serious dermal toxicity and drug resistance. Although numerous researchers were devoted to finding alternatives or therapies as combination treatments with So to reach more desired therapeutic efficacy, the therapeutic options were still limited. The present study prepares RGD pentapeptide decorated biomimic reconstituted high-density lipoprotein (rHDL) loaded with So and antimiRNA21 (RGD-rHDL/So/antimiRNA21) for enhanced HCC therapy. The RGD-rHDL/So/antimiRNA21 NPs offer an effective platform for anti-tumor and anti-angiogenesis therapy in HCC and provide new approach to reverse drug-resistance of So for feasible clinical application.

Endocytosis of lipoproteins

During their metabolism, all lipoproteins undergo endocytosis, either to be degraded intracellularly, for example in hepatocytes or macrophages, or to be re-secreted, for example in the course of transcytosis by endothelial cells. Moreover, there are several examples of internalized lipoproteins sequestered intracellularly, possibly to exert intracellular functions, for example the cytolysis of trypanosoma. Endocytosis and the subsequent intracellular itinerary of lipoproteins hence are key areas for understanding the regulation of plasma lipid levels as well as the biological functions of lipoproteins. Indeed, the identification of the low-density lipoprotein (LDL)-receptor and the unraveling of its transcriptional regulation led to the elucidation of familial hypercholesterolemia as well as to the development of statins, the most successful therapeutics for lowering of cholesterol levels and risk of atherosclerotic cardiovascular diseases. Novel limiting factors of intracellular trafficking of LDL and the LDL receptor continue to be discovered and to provide drug targets such as PCSK9. Surprisingly, the receptors mediating endocytosis of high-density lipoproteins or lipoprotein(a) are still a matter of controversy or even new discovery. Finally, the receptors and mechanisms, which mediate the uptake of lipoproteins into non-degrading intracellular itineraries for re-secretion (transcytosis, retroendocytosis), storage, or execution of intracellular functions, are largely unknown.

Principled multi-omic analysis reveals gene regulatory mechanisms of phenotype variation

Recent studies have analyzed large-scale data sets of gene expression to identify genes associated with interindividual variation in phenotypes ranging from cancer subtypes to drug sensitivity, promising new avenues of research in personalized medicine. However, gene expression data alone is limited in its ability to reveal cis-regulatory mechanisms underlying phenotypic differences. In this study, we develop a new probabilistic model, called pGENMi, that integrates multi-omic data to investigate the transcriptional regulatory mechanisms underlying interindividual variation of a specific phenotype—that of cell line response to cytotoxic treatment. In particular, pGENMi simultaneously analyzes genotype, DNA methylation, gene expression, and transcription factor (TF)-DNA binding data, along with phenotypic measurements, to identify TFs regulating the phenotype. It does so by combining statistical information about expression quantitative trait loci (eQTLs) and expression-correlated methylation marks (eQTMs) located within TF binding sites, as well as observed correlations between gene expression and phenotype variation. Application of pGENMi to data from a panel of lymphoblastoid cell lines treated with 24 drugs, in conjunction with ENCODE TF ChIP data, yielded a number of known as well as novel (TF, Drug) associations. Experimental validations by TF knockdown confirmed 41% of the predicted and tested associations, compared to a 12% confirmation rate of tested nonassociations (controls). An extensive literature survey also corroborated 62% of the predicted associations above a stringent threshold. Moreover, associations predicted only when combining eQTL and eQTM data showed higher precision compared to an eQTL-only or eQTM-only analysis using pGENMi, further demonstrating the value of multi-omic integrative analysis.

Experimental challenges regarding the in vitro investigation of the nanoparticle-biocorona in disease states

Toxicological evaluation of nanoparticles (NPs) requires the utilization of in vitro techniques due to their number and diverse properties. Cell culture systems are often lacking in their ability to perform comparative toxicity assessment due to dosimetry issues and capacity to simulate in vivo environments. Upon encountering a physiological environment, NPs become coated with biomolecules forming a biocorona (BC), influencing function, biodistribution, and toxicity. Disease-induced alterations in the biological milieu can alter BC formation. This study evaluates the role of low-density lipoprotein (LDL) in altering macrophage responses to iron oxide (Fe₃O₄) NPs. BCs were formed by incubating Fe₃O₄ NPs in serum-free media, or 10% fetal bovine serum with or without LDL present. Following exposures to a normalized dose (25 μg/mL), macrophage association of Fe₃O₄ NPs with a LDL-BC was enhanced. TNF-α mRNA expression and protein levels were differentially induced due to BCs. Cell surface expression of SR-B1 was reduced following all Fe₃O₄ NPs exposures, while only NPs with an LDL-BC enhanced mitochondrial membrane potential. These findings suggest that elevations in LDL may contribute to distinct BC formation thereby influencing NP-cellular interactions and response. Further, our study highlights challenges that may arise during the in vitro evaluation of disease-related variations in the NP-BC.

HDL-AuNPs-BMS Nanoparticle Conjugates as Molecularly Targeted Therapy for Leukemia

Gold nanoparticles (AuNPs) with adsorbed high-density lipoprotein (HDL) have been utilized to deliver oligonucleotides, yet HDL-AuNPs functionalized with small-molecule inhibitors have not been systematically explored. Here, we report an AuNP-based therapeutic system (HDL-AuNPs-BMS) for acute myeloid leukemia (AML) by delivering BMS309403 (BMS), a small molecule that selectively inhibits AML-promoting factor fatty acid-binding protein 4. To synthesize HDL-AuNPs-BMS, we use AuNP as a template to control conjugate size ensuring a spherical shape to engineer HDL-like nanoparticles containing BMS. The zeta potential and size of the HDL-AuNPs obtained from transmission electron microscopy demonstrate that the HDL-AuNPs-BMS are electrostatically stable and 25 nm in diameter. Functionally, compared to free drug, HDL-AuNPs-BMS conjugates are more readily internalized by AML cells and have more pronounced effects on downregulation of DNA methyltransferase 1 (DNMT1), induction of DNA hypomethylation, and restoration of epigenetically silenced tumor suppressor p15^INK4B coupled with AML growth arrest. Importantly, systemic administration of HDL-AuNPs-BMS conjugates into AML-bearing mice inhibits DNMT1-dependent DNA methylation, induces AML cell differentiation, and diminishes AML disease progression without obvious side effects. In summary, these data, for the first time, demonstrate HDL-AuNPs as an effective delivery platform with great potential to attach distinct inhibitors and HDL-AuNPs-BMS conjugates as a promising therapeutic platform to treat leukemia.

High-density lipoprotein-mimicking nanodiscs carrying peptide for enhanced therapeutic angiogenesis in diabetic hindlimb ischemia

Therapeutic strategies using endogenous stem cell mobilizer can provide effective cell-free therapy for addressing various ischemic diseases. In particular, substance P (SP) exhibited therapeutic regeneration by facilitating mobilization of endogenous stem cells from bone marrow to the injured sites. However, its therapeutic effect has been limited due to short half-life and rapid degradation of administered SP peptides in vivo. Here we sought to develop high-density lipoprotein (HDL)-mimicking nanodiscs conjugated with SP (HDL-SP) in order to increase the in vivo half-life, bone marrow targeting, and therapeutic efficacy of SP for the treatment of diabetic peripheral ischemia. Conjugation of SP onto HDL nanodisc led to remarkable ∼3215- and ∼1060-fold increase in the ex vivo and in vivo half-lives of SP, respectively. Accordingly, HDL-SP nanodiscs improved retention of SP in bone marrow after systemic administration, leading to efficient mobilization of stem cells from bone marrow into blood circulation and reduction of systemic inflammation. Consequently, nanodisc based SP peptide delivery promoted blood vessel formation, blood perfusion recovery and markedly improved limb salvage in diabetic hindlimb ischemia model relative to administration of free SP without nanodisc modification. Therefore, HDL-SP nanodisc can provide a novel strategy for the treatment of diabetic ischemia and HDL nanodisc modification could be potentially useful for the extension of plasma circulation of other labile peptides.

Sonication-Based Basic Protocol for Liposome Synthesis

Liposomes are spherical vesicles with a wide range of sizes from nano- to micrometer scale. For the past 7-8 decades, these vesicles have occupied the interest of a variety of scientists due to its physical, chemical, and mathematical properties and, to say the least, for its immense utility and potential as delivery vehicles for toxic and nontoxic excipients into biological tissues. Methods related to selection of reagents for creation of specific liposomes of certain properties are beyond the scope of this chapter, but here, we would outline a simplistic protocol to prepare and qualify an uniform batch of simple liposome with basic cargo. This chapter will attempt to provide the reader with a starting point for this immensely potent tool to build upon the right kind of liposome, appropriate for their studies.

Low scavenger receptor class B type I expression is associated with gastric adenocarcinoma tumor aggressiveness

Scavenger receptor class B type I (SR-BI), a well-documented high-density lipoprotein receptor, has been implicated in the development and progression of human cancer. However, little is known regarding the expression profile and clinical value of SR-BI in gastric adenocarcinoma. In the present study immunohistochemistry analysis was performed on a well-annotated gastric adenocarcinoma tissue microarray to investigate the association between SR-BI expression and clinicopathological parameters or patient outcome. The results revealed that SR-BI expression was detected in 69% of the 84 gastric adenocarcinomas. Moreover, a significant association was observed between low SR-BI expression and poor histological grade, higher Tumor-Node-Metastasis T stage, higher N stage and diffuse type carcinoma. Low SR-BI expression was also significantly associated with a shorter overall survival time in patients with gastric adenocarcinoma, although it was not an independent prognostic factor. Overall, the results of the present study demonstrated that SR-BI was possibly involved in gastric carcinogenesis and could be used as a biomarker to predict malignancy of gastric adenocarcinoma.

Lipoproteins for therapeutic delivery: recent advances and future opportunities

The physiological role(s) of mammalian plasma lipoproteins is to transport hydrophobic molecules (primarily cholesterol and triacylglycerols) to their respective destinations. Lipoproteins have also been studied as drug-delivery agents due to their advantageous payload capacity, long residence time in the circulation and biocompatibility. The purpose of this review is to briefly discuss current findings with the focus on each type of formulation's potential for clinical applications. Regarding utilizing lipoprotein type formulation for cancer therapeutics, their potential for tumor-selective delivery is also discussed.

Trans10,cis12 conjugated linoleic acid inhibits proliferation and migration of ovarian cancer cells by inducing ER stress, autophagy, and modulation of Src

The goal of this study was to investigate the anti-cancer effects of Trans10,cis12 conjugated linoleic acid (t10,c12 CLA). MTT assays and QCM™ chemotaxis 96-wells were used to test the effect of t10,c12 CLA on the proliferation and migration and invasion of cancer cells. qPCR and Western Blotting were used to determine the expression of specific factors. RNA sequencing was conducted using the Illumina platform and apoptosis was measured using a flow cytometry assay. t10,c12 CLA (IC50, 7 μM) inhibited proliferation of ovarian cancer cell lines SKOV-3 and A2780. c9,t11 CLA did not attenuate the proliferation of these cells. Transcription of 165 genes was significantly repressed and 28 genes were elevated. Genes related to ER stress, ATF4, CHOP, and GADD34 were overexpressed whereas EDEM2 and Hsp90, genes required for proteasomal degradation of misfolded proteins, were downregulated upon treatment. While apoptosis was not detected, t10,c12 CLA treatment led to 9-fold increase in autophagolysosomes and higher levels of LC3-II. G1 cell cycle arrest in treated cells was correlated with phosphorylation of GSK3β and loss of β-catenin. microRNA miR184 and miR215 were upregulated. miR184 likely contributed to G1 arrest by downregulating E2F1. miR215 upregulation was correlated with increased expression of p27/Kip-1. t10,c12 CLA-mediated inhibition of invasion and migration correlated with decreased expression of PTP1b and decreased Src activation by inhibiting phosphorylation at Tyr416. Due to its ability to inhibit proliferation and migration, t10,c12 CLA should be considered for treatment of ovarian cancer.

Reconstituted high-density lipoproteins: novel biomimetic nanocarriers for drug delivery

High-density lipoproteins (HDL) are naturally-occurring nanoparticles that are biocompatible, non-immunogenic and completely biodegradable. These endogenous particles can circulate for an extended period of time and transport lipids, proteins and microRNA from donor cells to recipient cells. Based on their intrinsic targeting properties, HDL are regarded as promising drug delivery systems. In order to produce on a large scale and to avoid blood borne pollution, reconstituted high-density lipoproteins (rHDL) possessing the biological properties of HDL have been developed. This review summarizes the biological properties and biomedical applications of rHDL as drug delivery platforms. It focuses on the emerging approaches that have been developed for the generation of biomimetic nanoparticles rHDL to overcome the biological barriers to drug delivery, aiming to provide an alternative, promising avenue for efficient targeting transport of nanomedicine.

SR-B1: A Unique Multifunctional Receptor for Cholesterol Influx and Efflux

The scavenger receptor, class B type 1 (SR-B1), is a multiligand membrane receptor protein that functions as a physiologically relevant high-density lipoprotein (HDL) receptor whose primary role is to mediate selective uptake or influx of HDL-derived cholesteryl esters into cells and tissues. SR-B1 also facilitates the efflux of cholesterol from peripheral tissues, including macrophages, back to liver. As a regulator of plasma membrane cholesterol content, SR-B1 promotes the uptake of lipid soluble vitamins as well as viral entry into host cells. These collective functions of SR-B1 ultimately affect programmed cell death, female fertility, platelet function, vasculature inflammation, and diet-induced atherosclerosis and myocardial infarction. SR-B1 has also been identified as a potential marker for cancer diagnosis and prognosis. Finally, the SR-B1-linked selective HDL-cholesteryl ester uptake pathway is now being evaluated as a gateway for the delivery of therapeutic and diagnostic agents. In this review, we focus on the regulation and functional significance of SR-B1 in mediating cholesterol movement into and out of cells.

Synthetic high-density lipoproteins as targeted monotherapy for chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) remains incurable despite the introduction of new drugs. Therapies targeting receptors and pathways active specifically in malignant B cells might provide better treatment options. For instance, in B cell lymphoma, our group has previously shown that scavenger receptor type B-1 (SR-B1), the high-affinity receptor for cholesterol-rich high-density lipoproteins (HDL), is a therapeutic target. As evidence suggests that targeting cholesterol metabolism in CLL cells may have therapeutic benefit, we examined SR-B1 expression in primary CLL cells from patients. Unlike normal B cells that do not express SR-B1, CLL cells express the receptor. As a result, we evaluated cholesterol-poor synthetic HDL nanoparticles (HDL NP), known for targeting SR-B1, as a therapy for CLL. HDL NPs potently and selectively induce apoptotic cell death in primary CLL cells. HDL NPs had no effect on normal peripheral blood mononuclear cells from healthy individuals or patients with CLL. These data implicate SR-B1 as a target in CLL and HDL NPs as targeted monotherapy for CLL.

SR-B1-targeted nanodelivery of anti-cancer agents: a promising new approach to treat triple-negative breast cancer

Patients with triple-negative breast cancer (TNBC) have a considerably less favorable prognosis than those with hormone-positive breast cancers. TNBC patients do not respond to current endocrine treatment and have a 5-year survival prognosis of <30%. The research presented here is intended to fill a void toward the much needed development of improved treatment strategies for metastatic TNBC. The overall goal of this research was to evaluate the effectiveness of reconstituted high-density lipoprotein (rHDL) nanoparticles (NPs) as delivery agents for anti-TNBC drugs. Using lapatinib and valrubicin as components of the rHDL/drug complexes resulted in a significantly better performance of the NP-transported drugs compared with their free (unencapsulated) counterparts. The enhancement of the therapeutic effect and the protection of normal cells (cardiomyocytes) achieved via the rHDL NPs were likely due to the overexpression of the high-density lipoprotein (HDL) (scavenger receptor class B type 1 [SR-B1]) receptor by the TNBC cells.

Effect of size and pegylation of liposomes and peptide-based synthetic lipoproteins on tumor targeting

Synthetic high-density lipoprotein nanoparticles (sHDL) are a valuable class of nanomedicines with established animal safety profile, clinical tolerability and therapeutic efficacy for cardiovascular applications. In this study we examined how the scavenger receptor B-I-mediated (SR-BI) tumor-targeting ability of sHDL, long plasma circulation half-life, and small particle size (9.6±0.2nm) impacted sHDL accumulation in SR-BI positive colorectal carcinoma cells, 3D tumor spheroids, and in vivo xenografts. We compared tumor accumulation of sHDL with that of liposomes (LIP, 130.7±0.8nm), pegylated liposomes (PEG-LIP, 101±2nm), and pegylated sHDL (12.1±0.1nm), all prepared with the same lipid components. sHDL penetrated deep (210μm) into tumor spheroids and exhibited 12- and 3-fold higher in vivo solid tumor accumulation, compared with LIP (p<0.01) and PEG-LIP (p<0.05), respectively. These results suggest that sHDL with established human safety possess promising intrinsic tumor-targeted properties.

Superparamagnetic reconstituted high-density lipoprotein nanocarriers for magnetically guided drug delivery

Current cancer chemotherapy is frequently associated with short- and long-term side effects, affecting the quality of life of cancer survivors. Because malignant cells are known to overexpress specific surface antigens, including receptors, targeted drug delivery is often utilized to reduce or overcome side effects. The current study involves a novel targeting approach using specifically designed nanoparticles, including encapsulation of the anti-cancer drug valrubicin into superparamagnetic iron oxide nanoparticle (SPION) containing reconstituted high-density lipoprotein (rHDL) nanoparticles. Specifically, rHDL–SPION–valrubicin hybrid nanoparticles were assembled and characterized with respect to their physical and chemical properties, drug entrapment efficiency and receptor-mediated release of the drug valrubicin from the nanoparticles to prostate cancer (PC-3) cells. Prussian blue staining was used to assess nanoparticle movement in a magnetic field. Measurements of cytotoxicity toward PC-3 cells showed that rHDL–SPION–valrubicin nanoparticles were up to 4.6 and 31 times more effective at the respective valrubicin concentrations of 42.4 µg/mL and 85 µg/mL than the drug valrubicin alone. These studies showed, for the first time, that lipoprotein drug delivery enhanced via magnetic targeting could be an effective chemotherapeutic strategy for prostate cancer.

Targeting the SR-B1 Receptor as a Gateway for Cancer Therapy and Imaging

Malignant tumors display remarkable heterogeneity to the extent that even at the same tissue site different types of cells with varying genetic background may be found. In contrast, a relatively consistent marker the scavenger receptor type B1 (SR-B1) has been found to be consistently overexpressed by most tumor cells. Scavenger Receptor Class B Type I (SR-BI) is a high density lipoprotein (HDL) receptor that facilitates the uptake of cholesterol esters from circulating lipoproteins. Additional findings suggest a critical role for SR-BI in cholesterol metabolism, signaling, motility, and proliferation of cancer cells and thus a potential major impact in carcinogenesis and metastasis. Recent findings indicate that the level of SR-BI expression correlate with aggressiveness and poor survival in breast and prostate cancer. Moreover, genomic data show that depending on the type of cancer, high or low SR-BI expression may promote poor survival. This review discusses the importance of SR-BI as a diagnostic as well as prognostic indicator of cancer to help elucidate the contributions of this protein to cancer development, progression, and survival. In addition, the SR-B1 receptor has been shown to serve as a potential gateway for the delivery of therapeutic agents when reconstituted high density lipoprotein nanoparticles are used for their transport to cancer cells and tumors. Opportunities for the development of new technologies, particularly in the areas of cancer therapy and tumor imaging are discussed.

Combining Anti-Mir-155 with Chemotherapy for the Treatment of Lung Cancers

Purpose: The oncogenic miR-155 is upregulated in many human cancers, and its expression is increased in more aggressive and therapy-resistant tumors, but the molecular mechanisms underlying miR-155-induced therapy resistance are not fully understood. The main objectives of this study were to determine the role of miR-155 in resistance to chemotherapy and to evaluate anti-miR-155 treatment to chemosensitize tumors.Experimental Design: We performed in vitro studies on cell lines to investigate the role of miR-155 in therapy resistance. To assess the effects of miR-155 inhibition on chemoresistance, we used an in vivo orthotopic lung cancer model of athymic nude mice, which we treated with anti-miR-155 alone or in combination with chemotherapy. To analyze the association of miR-155 expression and the combination of miR-155 and TP53 expression with cancer survival, we studied 956 patients with lung cancer, chronic lymphocytic leukemia, and acute lymphoblastic leukemia.Results: We demonstrate that miR-155 induces resistance to multiple chemotherapeutic agents in vitro, and that downregulation of miR-155 successfully resensitizes tumors to chemotherapy in vivo We show that anti-miR-155-DOPC can be considered non-toxic in vivo We further demonstrate that miR-155 and TP53 are linked in a negative feedback mechanism and that a combination of high expression of miR-155 and low expression of TP53 is significantly associated with shorter survival in lung cancer.Conclusions: Our findings support the existence of an miR-155/TP53 feedback loop, which is involved in resistance to chemotherapy and which can be specifically targeted to overcome drug resistance, an important cause of cancer-related death. Clin Cancer Res; 23(11); 2891-904. ©2016 AACR.

A high-density lipoprotein-mediated drug delivery system

High-density lipoprotein (HDL) is a comparatively dense and small lipoprotein that can carry lipids as a multifunctional aggregate in plasma. Several studies have shown that increasing the levels or improving the functionality of HDL is a promising target for treating a wide variety of diseases. Among lipoproteins, HDL particles possess unique physicochemical properties, including naturally synthesized physiological components, amphipathic apolipoproteins, lipid-loading and hydrophobic agent-incorporating characteristics, specific protein-protein interactions, heterogeneity, nanoparticles, and smaller size. Recently, the feasibility and superiority of using HDL particles as drug delivery vehicles have been of great interest. In this review, we summarize the structure, constituents, biogenesis, remodeling, and reconstitution of HDL drug delivery systems, focusing on their delivery capability, characteristics, applications, manufacturing, and drug-loading and drug-targeting characteristics. Finally, the future prospects are presented regarding the clinical application and challenges of using HDL as a pharmacodelivery carrier.

Properties of Native High-Density Lipoproteins Inspire Synthesis of Actively Targeted In Vivo siRNA Delivery Vehicles

Efficient systemic administration of therapeutic short interfering RNA (siRNA) is challenging. High-density lipoproteins (HDL) are natural in vivo RNA delivery vehicles. Specifically, native HDLs: 1) Load single-stranded RNA; 2) Are anionic, which requires charge reconciliation between the RNA and HDL, and 3) Actively target scavenger receptor type B-1 (SR-B1) to deliver RNA. Emphasizing these particular parameters, we employed templated lipoprotein particles (TLP), mimics of spherical HDLs, and self-assembled them with single-stranded complements of, presumably, any highly unmodified siRNA duplex pair after formulation with a cationic lipid. Resulting siRNA templated lipoprotein particles (siRNA-TLP) are anionic and tunable with regard to RNA assembly and function. Data demonstrate that the siRNA-TLPs actively target SR-B1 to potently reduce androgen receptor (AR) and enhancer of zeste homolog 2 (EZH2) proteins in multiple cancer cell lines. Systemic administration of siRNA-TLPs demonstrated no off-target toxicity and significantly reduced the growth of prostate cancer xenografts. Thus, native HDLs inspired the synthesis of a hybrid siRNA delivery vehicle that can modularly load single-stranded RNA complements after charge reconciliation with a cationic lipid, and that function due to active targeting of SR-B1.

Lipoproteins and lipoprotein mimetics for imaging and drug delivery

Lipoproteins are a set of natural nanoparticles whose main role is the transport of fats within the body. While much work has been done to develop synthetic nanocarriers to deliver drugs or contrast media, natural nanoparticles such as lipoproteins represent appealing alternatives. Lipoproteins are biocompatible, biodegradable, non-immunogenic and are naturally targeted to some disease sites. Lipoproteins can be modified to act as contrast agents in many ways, such as by insertion of gold cores to provide contrast for computed tomography. They can be loaded with drugs, nucleic acids, photosensitizers or boron to act as therapeutics. Attachment of ligands can re-route lipoproteins to new targets. These attributes render lipoproteins attractive and versatile delivery vehicles. In this review we will provide background on lipoproteins, then survey their roles as contrast agents, in drug and nucleic acid delivery, as well as in photodynamic therapy and boron neutron capture therapy.

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.

HDL and microRNA therapeutics in cardiovascular disease

microRNAs (miRNA) are small non-coding RNAs (sRNA) that post-transcriptionally regulate gene (mRNA) expression and are implicated in many biological processes and diseases. Many miRNAs have been reported to be altered in cardiovascular disease (CVD); both cellular and extracellular miRNA levels are affected by hypercholesterolemia and atherosclerosis. We and other groups have reported that lipoproteins transport miRNAs in circulation and these lipoprotein signatures are significantly altered in hypercholesterolemia and coronary artery disease (CAD). Extracellular miRNAs are a new class of potential biomarkers for CVD; however, they may also be new drug targets as high-density lipoproteins (HDL) transfer functional miRNAs to recipient cells in an endocrine-like form of intercellular communication that likely suppresses vascular inflammation. Recently, RNA-based drugs have emerged as the next frontier in drug therapy, and there are many miRNA inhibitors and mimics in clinical development. Here, we discuss specific miRNA drug targets and how their manipulation may impact CVD. We also address the potential for manipulating HDL-miRNA levels to treat CVD and the use of HDL as a delivery vehicle for RNA and chemical drugs. Finally, we outline the current and future challenges for HDL and miRNA-based therapeutics for the prevention and treatment of CVD.

Targeted nanoparticles for colorectal cancer

Colorectal cancer (CRC) is highly prevalent worldwide, and despite notable progress in treatment still leads to significant morbidity and mortality. The use of nanoparticles as a drug delivery system has become one of the most promising strategies for cancer therapy. Targeted nanoparticles could take advantage of differentially expressed molecules on the surface of tumor cells, providing effective release of cytotoxic drugs. Several efforts have recently reported the use of diverse molecules as ligands on the surface of nanoparticles to interact with the tumor cells, enabling the effective delivery of antitumor agents. Here, we present recent advances in targeted nanoparticles against CRC and discuss the promising use of ligands and cellular targets in potential strategies for the treatment of CRCs.

Lipoprotein-Related and Apolipoprotein-Mediated Delivery Systems for Drug Targeting and Imaging

The integration of lipoprotein-related or apolipoprotein-targeted nanoparticles as pharmaceutical carriers opens new therapeutic and diagnostic avenues in nanomedicine. The concept is to exploit the intrinsic characteristics of lipoprotein particles as being the natural transporter of apolar lipids and fat in human circulation. Discrete lipoprotein assemblies and lipoprotein-based biomimetics offer a versatile nanoparticle platform that can be manipulated and tuned for specific medical applications. This article reviews the possibilities for constructing drug loaded, reconstituted or artificial lipoprotein particles. The advantages and limitations of lipoproteinbased delivery systems are critically evaluated and potential future challenges, especially concerning targeting specificity, concepts for lipoprotein rerouting and design of innovative lipoprotein mimetic particles using apolipoprotein sequences as targeting moieties are discussed. Finally, the review highlights potential medical applications for lipoprotein-based nanoparticle systems in the fields of cardiovascular research, cancer therapy, gene delivery and brain targeting focusing on representative examples from literature.

Reconstituted high density lipoprotein mediated targeted co-delivery of HZ08 and paclitaxel enhances the efficacy of paclitaxel in multidrug-resistant MCF-7 breast cancer cells

In the past decades, reconstituted high density lipoprotein (rHDL) has been successfully developed as a drug carrier since the enhanced HDL-lipids uptake is demonstrated in several human cancers. In this paper, rHDL, for the first time, was utilized to co-encapsulate two hydrophobic drugs: an anticancer drug, paclitaxel (PTX), and a new reversal agent for P-gp (P-glycoprotein)-mediated multidrug resistance (MDR) of cancer, N-cyano-1-[(3,4-dimethoxyphenyl)methyl]-3,4-dihydro-6,7-dimethoxy-N'-octyl-2(1H)-isoquinoline-carboximidamide (HZ08). We proposed this drug co-delivery strategy to reverse PTX resistance. The study aimed to develop a biomimetic nanovector, reconstituted high density lipoprotein (rHDL), mediating targeted PTX-HZ08 delivery for cancer therapy. Using sodium cholate dialysis method, we successfully formulated dual-agent co-delivering rHDL nanoparticles (PTX-HZ08-rHDL NPs) with a typical spherical morphology, well-distributed size (~100nm), high drug encapsulation efficiency (approximately 90%), sustained drug release properties and exceptional stability even after storage for 1month or incubation in 10% fetal bovine serum (FBS) DMEM for up to 2days. Results demonstrated that PTX-HZ08-rHDL NPs significantly enhanced anticancer efficacy in vitro, including higher cytotoxicity and better ability to induce cell apoptosis against both PTX-sensitive and -resistant MCF-7 human breast cancer cell lines (MCF-7 and MCF-7/PTX cells). Mechanism studies demonstrated that these improvements could be correlated with increased cellular uptake of PTX mediated by scavenger receptor class B type I (SR-BI) as well as prolonged intracellular retention of PTX due to the HZ08 mediated drug-efflux inhibition. In addition, in vivo investigation showed that the PTX-HZ08-rHDL NPs were substantially safer, have higher tumor-targeted capacity and have stronger antitumor activity than the corresponding dosage of paclitaxel injection. These findings suggested that rHDL NPs could be an ideal tumor-targeted nanovector for simultaneous transfer of insoluble anticancer drug and drug resistance reversal agents. The PTX-HZ08-rHDL NPs co-delivery system might be a new promising strategy to overcome tumor drug resistance.

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

Regulation of gene expression using p53 is a promising strategy for treatment of numerous cancers, and chemotherapeutic drug dichloroacetate (DCA) induces apoptosis and growth inhibition in tumor, without apparent toxicity in normal tissues. Combining DCA and p53 gene could be an effective way to treat tumors. The progress towards broad applications of DCA/p53 combination requires the development of safe and efficient vectors that target to specific cells. In this study, we developed a DSPE-PEG-AA (1,2-distearoryl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethyleneglycol-2000)] ammonium salt-anisamide) modified reconstituted high-density lipoprotein-based DCA/p53-loaded nanoparticles (DSPE-PEG-AA/rHDL/DCA-PEI/p53 complexes), which was fabricated as a drug/gene dual-targeting co-delivery system for potential cancer therapy. Here, DCA-PEI was utilized to effectively condense the p53 plasmid, to incorporate the plasmid into rHDL and to act as an antitumor drug to inhibit tumor cell growth. The DSPE-PEG-AA/rHDL/DCA-PEI/p53 complexes exhibited desirable and homogenous particle size, neutral surface charge and low cytotoxicity for normal cells in vitro. The results of confocal laser scanning microscopy (CLSM) and flow cytometry confirmed that the scavenger receptor class B type I (SR-BI) and sigma receptor mediated dual-targeting function of the complexes inducing efficient cytoplasmic drug delivery and gene transfection in human lung adenocarcinoma cell line A549. And in vivo investigation on nude mice bearing A549 tumor xenografts revealed that DSPE-PEG-AA/rHDL/DCA-PEI/p53 complexes possessed specific tumor targeting and strong antitumor activity. The work described here demonstrated that the DSPE-PEG-AA/rHDL/DCA-PEI/p53 complexes might offer a promising tool for effective cancer therapy.