Prostate-targeted biodegradable nanoparticles loaded with androgen receptor silencing constructs eradicate xenograft tumors in mice

PLGA nanomedical consignation: A novel approach for the management of prostate cancer

The malignancy of the prostate is a complicated ailment which impacts millions of male populations around the globe. Despite the multitude of endeavour accomplished within this domain, modalities that are involved in the ameliorative management of predisposed infirmity are still relent upon non-specific and invasive procedures, thus imposing a detrimental mark on the living standard of the individual. Also, the orchestrated therapeutic interventions are still incompetent in substantiating a robust and unabridged therapeutic end point owing to their inadequate solubility, low bioavailability, limited cell assimilation, and swift deterioration, thereby muffling the clinical application of these existing treatment modalities. Nanotechnology has been employed in an array of modalities for the medical management of malignancies. Among the assortment of available nano-scaffolds, nanocarriers composed of a bio-decomposable and hybrid polymeric material like PLGA hold an opportunity to advance as standard chemotherapeutic modalities. PLGA-based nanocarriers have the prospect to address the drawbacks associated with conventional cancer interventions, owing to their versatility, durability, nontoxic nature, and their ability to facilitate prolonged drug release. This review intends to describe the plethora of evidence-based studies performed to validate the applicability of PLGA nanosystem in the amelioration of prostate malignancies, in conjunction with PLGA focused nano-scaffold in the clinical management of prostate carcinoma. This review seeks to explore numerous evidence-based studies confirming the applicability of PLGA nanosystems in ameliorating prostate malignancies. It also delves into the role of PLGA-focused nano-scaffolds in the clinical management of prostate carcinoma, aiming to provide a comprehensive perspective on these advancements.

Recent advances and future perspectives in the therapeutics of prostate cancer

Prostate cancer (PC) is one of the most common cancers in males and the fifth leading reason of death. Age, ethnicity, family history, and genetic defects are major factors that determine the aggressiveness and lethality of PC. The African population is at the highest risk of developing high-grade PC. It can be challenging to distinguish between low-risk and high-risk patients due to the slow progression of PC. Prostate-specific antigen (PSA) is a revolutionary discovery for the identification of PC. However, it has led to an increase in over diagnosis and over treatment of PC in the past few decades. Even if modifications are made to the standard PSA testing, the specificity has not been found to be significant. Our understanding of PC genetics and proteomics has improved due to advances in different fields. New serum, urine, and tissue biomarkers, such as PC antigen 3 (PCA3), have led to various new diagnostic tests, such as the prostate health index, 4K score, and PCA3. These tests significantly reduce the number of unnecessary and repeat biopsies performed. Chemotherapy, radiotherapy, and prostatectomy are standard treatment options. However, newer novel hormone therapy drugs with a better response have been identified. Androgen deprivation and hormonal therapy are evolving as new and better options for managing hormone-sensitive and castration-resistant PC. This review aimed to highlight and discuss epidemiology, various risk factors, and developments in PC diagnosis and treatment regimens.

siRNA-based approaches for castration-resistant prostate cancer therapy targeting the androgen receptor signaling pathway

Androgen deprivation therapy is a common treatment method for metastatic prostate cancer through lowering androgen levels; however, this therapy frequently leads to the development of castration-resistant prostate cancer (CRPC). This is attributed to the activation of the androgen receptor (AR) signaling pathway. Current treatments targeting AR are often ineffective mostly due to AR gene overexpression and mutations, as well as the presence of splice variants that accelerate CRPC progression. Thus there is a critical need for more specific medication to treat CRPC. Small interfering RNAs have shown great potential as a targeted therapy. This review discusses prostate cancer progression and the role of AR signaling in CRPC, and proposes siRNA-based targeted therapy as a promising strategy for CRPC.

Nuclear-targeted carbon quantum dot mediated CRISPR/Cas9 delivery for fluorescence visualization and efficient editing

Nuclear targeted delivery has great potential in improving the efficiency of non-viral carrier mediated genome editing. However, direct and efficient delivery of CRISPR/Cas9 plasmid into the nucleus remains a challenge. In this study, a nuclear targeted gene delivery platform based on fluorescent carbon quantum dots (CQDs) was developed. Polyethylenimine (PEI) and polyethylene glycol (PEG) synergistically passivated the surface of CQDs, providing an excitation-independent green-emitting fluorescent CQDs-PEI-PEG conjugate (CQDs-PP) with an ultra-small size and positive surface charge. Here we show that CQDs-PP could bind CRISPR/Cas9 plasmid to form a nano-complex by electrostatic attraction, which can bypass lysosomes and enter the nucleus by passive diffusion, and thereby improve the transfection efficiency. Also, CQDs-PP could deliver CRISPR/Cas9 plasmid into HeLa cells, resulting in the insertion/deletion mutation of the target EFHD1 gene. More importantly, CQDs-PP exhibited a considerably higher gene editing efficiency as well as comparable or lower cytotoxicity relative to Lipo2000 and PEI-passivated CQDs-PEI (CQDs-P). Thus, the nuclear-targeted CQDs-PP is expected to constitute an efficient CRISPR/Cas9 delivery carrier in vitro with imaging-trackable ability.

Anti-Androgen Receptor Therapies in Prostate Cancer: A Brief Update and Perspective

Prostate cancer is a major health issue in western countries and is the second leading cause of cancer death in American men. Prostate cancer depends on the androgen receptor (AR), a transcriptional factor critical for prostate cancer growth and progression. Castration by surgery or medical treatment reduces androgen levels, resulting in prostatic atrophy and prostate cancer regression. Thus, metastatic prostate cancers are initially managed with androgen deprivation therapy. Unfortunately, prostate cancers rapidly relapse after castration therapy and progress to a disease stage called castration-resistant prostate cancer (CRPC). Currently, clinical treatment for CRPCs is focused on suppressing AR activity with antagonists like Enzalutamide or by reducing androgen production with Abiraterone. In clinical practice, these treatments fail to yield a curative benefit in CRPC patients in part due to AR gene mutations or splicing variations, resulting in AR reactivation. It is conceivable that eliminating the AR protein in prostate cancer cells is a promising solution to provide a potential curative outcome. Multiple strategies have emerged, and several potent agents that reduce AR protein levels were reported to eliminate xenograft tumor growth in preclinical models via distinct mechanisms, including proteasome-mediated degradation, heat-shock protein inhibition, AR splicing suppression, blockage of AR nuclear localization, AR N-terminal suppression. A few small chemical compounds are undergoing clinical trials combined with existing AR antagonists. AR protein elimination by enhanced protein or mRNA degradation is a realistic solution for avoiding AR reactivation during androgen deprivation therapy in prostate cancers.

Targeting steroid hormone receptors for anti-cancer therapy-A review on small molecules and nanotherapeutic approaches

The steroid hormone receptors (SHRs) among nuclear hormone receptors (NHRs) are steroid ligand-dependent transcription factors that play important roles in the regulation of transcription of genes promoted via hormone responsive elements in our genome. Aberrant expression patterns and context-specific regulation of these receptors in cancer, have been routinely reported by multiple research groups. These gave an window of opportunity to target those receptors in the context of developing novel, targeted anticancer therapeutics. Besides the development of a plethora of SHR-targeting synthetic ligands and the availability of their natural, hormonal ligands, development of many SHR-targeted, anticancer nano-delivery systems and theranostics, especially based on small molecules, have been reported. It is intriguing to realize that these cytoplasmic receptors have become a hot target for cancer selective delivery. This is in spite of the fact that these receptors do not fall in the category of conventional, targetable cell surface bound or transmembrane receptors that enjoy over-expression status. Glucocorticoid receptor (GR) is one such exciting SHR that in spite of it being expressed ubiquitously in all cells, we discovered it to behave differently in cancer cells, thus making it a truly druggable target for treating cancer. This review selectively accumulates the knowledge generated in the field of SHR-targeting as a major focus for cancer treatment with various anticancer small molecules and nanotherapeutics on progesterone receptor, mineralocorticoid receptor, and androgen receptor while selectively emphasizing on GR and estrogen receptor. This review also briefly highlights lipid-modification strategy to convert ligands into SHR-targeted cancer nanotherapeutics. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Biology-Inspired Nanomaterials > Lipid-Based Structures Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Biogenic selenium nanoparticles produced by Lactobacillus casei ATCC 393 inhibit colon cancer cell growth in vitro and in vivo

Selenium compounds exhibit excellent anticancer properties but have a narrow therapeutic window. Selenium nanoparticles, however, are less toxic compared to other selenium forms, and their biogenic production leads to improved bioavailability. Herein, we used the probiotic strain Lactobacillus casei ATCC 393, previously shown to inhibit colon cancer cell growth, to synthesize biogenic selenium nanoparticles. We examined the anticancer activity of orally administered L. casei, L. casei-derived selenium nanoparticles and selenium nanoparticle-enriched L. casei, and investigated their antitumor potential in the CT26 syngeneic colorectal cancer model in BALB/c mice. Our results indicate that L. casei-derived selenium nanoparticles and selenium nanoparticle-enriched L. casei exert cancer-specific antiproliferative activity in vitro. Moreover, the nanoparticles were found to induce apoptosis and elevate reactive oxygen species levels in cancer cells. It is noteworthy that, when administered orally, selenium nanoparticle-enriched L. casei attenuated the growth of colon carcinoma in mice more effectively than the isolated nanoparticles or L. casei, suggesting a potential additive effect of the nanoparticles and the probiotic. To the best of our knowledge this is the first comparative study examining the anticancer effects of selenium nanoparticles synthesized by a microorganism, the selenium nanoparticle-enriched microorganism and the sole microorganism.

Functionalized nano-targeted moieties in management of prostate cancer

Multimodal properties of nanoparticles, such as simultaneously carrying drugs and/or diagnostic probes for site-specific delivery, make them excellent carriers for diagnosis and treatment of prostate cancer. Advantages are high permeability and selectivity to malignant cells to reduce systemic toxicity of chemotherapeutic drugs. Based on a review of current literature, the lack of efficient and highly specific prostate cancer cell targeting moieties is hindering successful in vivo prostate cancer-targeted drug delivery systems. Highly specific nano-targeting moieties as drug delivery vehicles might improve chemotherapeutic delivery via targeting to specific receptors expressed on the surface of prostate cancer cells. This review describes nano-targeting moieties for management of prostate cancer and its cancer stem cells. Descriptions of targeting moieties using anti-prostate-specific membrane antigen, aptamer, anti-cluster of differentiation 24/44, folic acid and other targeting strategies are highlighted. Current research results are promising and may yield development of next-generation nanoscale theragnostic targeted modalities for prostate cancer treatment.

Potential and Challenges of Aptamers as Specific Carriers of Therapeutic Oligonucleotides for Precision Medicine in Cancer

Due to the progress made in the area of precision and personalized medicine in the field of cancer therapy, strategies to selectively and specifically identify target molecules causative of the diseases are urgently needed. Efforts are being made by a number of different laboratories, companies, and researchers to develop therapeutic molecules that selectively recognize the tissues and the cells of interest, exhibit few or no off-target and side effects, are non-immunogenic, and have a strong action. Aptamers, artificially selected single-stranded DNA or RNA oligonucleotides, are promising molecules satisfying many of the requirements needed for diagnosis and precision medicine. Aptamers can also couple to their native mechanism of action the delivery of additional molecules (oligonucleotides, siRNAs, miRNAs) to target cells. In this review, we summarize recent progress in the aptamer-mediated strategy for the specific delivery of therapeutic oligonucleotides.

One-Step Formation of Chondrocytes through Direct Reprogramming via Polysaccharide-Based Gene Delivery

An innovative strategy for the generation of chondrocytes was thoroughly studied in this paper. Polyetherimide-modified polysaccharides of Porphyra yezoensis (pmPPY) served as a nonviral gene vector and delivered Sox9 plasmid to directly reprogram mouse embryonic fibroblasts into chondrocytes. The gene transfer efficiency was evaluated through ELISA, RT-PCR, and Western blot. The induced chondrocytes were identified through toluidine blue, Safranin O, and the immunostaining. The expression level of collagen II was finally evaluated through western blot. The pSox9/pmPPY nanoparticles (1:50) showed lower cytotoxicity as well as greater gene transfection efficiency than Lipofectamine 2000 and polyetherimide (PEI) (p<0.05). The results of toluidine blue, Safranin O, and the immunostaining of collagen II further showed that the normal MEFs were successfully reprogrammed into chondrocytes. These findings indicate that pmPPY could be a promising gene vector for the generation of chondrocytes via single-gene delivery strategy, which might provide abundant chondrocytes for cartilage repair.

Alternol eliminates excessive ATP production by disturbing Krebs cycle in prostate cancer

BACKGROUND

Alternol is a natural compound isolated from fermentation products of a mutant fungus. Our previous studies demonstrated that Alternol specifically kills cancer cells but spares benign cells.

METHODS

To investigate the mechanism underlying alternol-induced cancer cell-specific killing effect, we took a comprehensive strategy to identify Alternol's protein targets in prostate cancer cells, including PC-3, C4-2, and 22RV1, plus benign BPH1 cell lines. Major experimental techniques included biotin-streptavidin pulldown assay coupled with mass-spectrometry, in vitro enzyme activity assay for Krebs cycle enzymes and gas chromatography-mass spectrometry (GC-MS) for metabolomic analysis.

RESULTS

Among 14 verified protein targets, four were Krebs cycle enzymes, fumarate hydratase (FH), malate dehydrogenase-2 (MDH2), dihydrolipoamide acetyltransferase (DLAT) in pyruvate dehydrogenase complex (PDHC) and dihydrolipoamide S-succinyltransferase (DLST) in a-ketoglutarate dehydrogenase complex (KGDHC). Functional assays revealed that PDHC and KGDHC activities at the basal level were significantly higher in prostate cancer cells compared to benign prostate BPH1 cells, while alternol treatment reduced their activities in cancer cells close to the levels in BPH1 cells. Although FH and MDH2 activities were comparable among prostate cancer and benign cell lines at the basal level, Alternol treatment largely increased their activities in cancer cells. Metabolomic analysis revealed that Alternol treatment remarkably reduced the levels of malic acid, fumaric acid, and isocitric acid and mitochondrial respiration in prostate cancer cells. Alternol also drastically reduced mitochondrial respiration and ATP production in PC-3 cells in vitro or in xenograft tissues but not in BPH1 cells or host liver tissues.

CONCLUSIONS

Alternol interacts with multiple Krebs cycle enzymes, resulting in reduced mitochondrial respiration and ATP production in prostate cancer cells and xenograft tissues, providing a novel therapeutic strategy for prostate cancer treatment.

Advances in Receptor-Mediated, Tumor-Targeted Drug Delivery

Receptor-mediated drug delivery presents an opportunity to enhance therapeutic efficiency by accumulating drug within the tissue of interest and reducing undesired, off-target effects. In cancer, receptor overexpression is a platform for binding and inhibiting pathways that shape biodistribution, toxicity, cell binding and uptake, and therapeutic function. This review will identify tumor-targeted drug delivery vehicles and receptors that show promise for clinical translation based on quantitative in vitro and in vivo data. The authors describe the rationale to engineer a targeted drug delivery vehicle based on the ligand, chemical conjugation method, and type of drug delivery vehicle. Recent advances in multivalent targeting and ligand organization on tumor accumulation are discussed. Revolutionizing receptor-mediated drug delivery may be leveraged in the therapeutic delivery of chemotherapy, gene editing tools, and epigenetic drugs.

Targeted cancer drug delivery with aptamer-functionalized polymeric nanoparticles

Based on exceptional advantages of aptamers, increasing attention has been presented in the utilise of them as targeted ligands for cancer drug delivery. Recently, the progress of aptamer-targeted nanoparticles has presented new therapeutic systems for several types of cancer with decreased toxicity and improved efficacy. We highlight some of the promising formulations of aptamer-conjugated polymeric nanoparticles for specific targeted drug delivery to cancer cells. This review paper focuses on the current progresses in the use of the novel strategies to aptamer-targeted drug delivery for chemotherapy. An extensive literature review was performed using internet database, mainly PubMed based on MeSH keywords. The searches included full-text publications written in English without any limitation in date. The abstracts, reviews, books as well as studies without obvious relating of aptamers as targeted ligands for cancer drug delivery were excluded from the study. The reviewed literature revealed that aptamers with ability to modify and conjugate to various molecules can be used as targeted cancer therapy agents. However, development of aptamers unique to each individual's tumour to the development of personalised medicine seems to be needed.

Photoluminescent Cationic Carbon Dots as efficient Non-Viral Delivery of Plasmid SOX9 and Chondrogenesis of Fibroblasts

With the increasing demand for higher gene carrier performance, a multifunctional vector could immensely simplify gene delivery for disease treatment; nevertheless, the current non- viral vectors lack self-tracking ability. Here, a type of novel, dual-functional cationic carbon dots (CDs), produced through one-step, microwave-assisted pyrolysis of arginine and glucose, have been utilized as both a self-imaging agent and a non-viral gene vector for chondrogenesis from fibroblasts. The cationic CDs could condense the model gene plasmid SOX9 (pSOX9) to form ultra-small (10–30 nm) nanoparticles which possessed several favorable properties, including high solubility, tunable fluorescence, high yield, low cytotoxicity and outstanding biocompatibility. The MTT assay indicated that CDs/pSOX9 nanoparticles had little cytotoxicity against mouse embryonic fibroblasts (MEFs) compared to Lipofectamine2000 and PEI (25 kDa). Importantly, the CDs/pSOX9 nanoparticles with tunable fluorescence not only enabled the intracellular tracking of the nanoparticles, but also could successfully deliver the pSOX9 into MEFs with significantly high efficiency. Furthermore, the CDs/pSOX9 nanoparticles-mediated transfection of MEFs showed obvious chondrogenic differentiation. Altogether, these findings demonstrated that the CDs prepared in this study could serve as a paradigmatic example of the dual-functional reagent for both self-imaging and effective non-viral gene delivery.

Aptamer delivery of siRNA, radiopharmaceutics and chemotherapy agents in cancer

Aptamers are oligonucleotide reagents with high affinity and specificity, which among other therapeutic and diagnostic applications have the capability of acting as delivery agents. Thus, aptamers are capable of carrying small molecules, nanoparticles, radiopharmaceuticals or fluorescent agents as well as nucleic acid therapeutics specifically to their target cells. In most cases, the molecules may possess interesting therapeutic properties, but their lack of specificity for a particular cell type, or ability to internalise in such a cell, hinders their clinical development, or cause unwanted side effects. Thus, chemotherapy or radiotherapy agents, famous for their side effects, can be coupled to aptamers for specific delivery. Equally, siRNA have great therapeutic potential and specificity, but one of their shortcomings remain the delivery and internalisation into cells. Various methodologies have been proposed to date, including aptamers, to resolve this problem. Therapeutic or imaging reagents benefit from the adaptability and ease of chemical manipulation of aptamers, their high affinity for the specific marker of a cell type, and their internalisation ability via cell mediated endocytosis. In this review paper, we explore the potential of the aptamers as delivery agents and offer an update on current status and latest advancements.

Enhancing DPYSL3 gene expression via a promoter-targeted small activating RNA approach suppresses cancer cell motility and metastasis

To explore a novel strategy in suppressing tumor metastasis, we took the advantage of a recent RNA activation (RNAa) theory and used small double-strand RNA molecules, termed as small activating RNAs (saRNA) that are complimentary to target gene promoter, to enhance transcription of metastasis suppressor gene. The target gene in this study is Dihydro-pyrimidinase-like 3 (DPYSL3, protein name CRMP4), which was identified as a metastatic suppressor in prostate cancers. There are two transcriptional variants of DPYSL3 gene in human genome, of which the variant 2 is the dominant transcript (DPYSL3v2, CRMP4a) but is also significantly down-regulated in primary prostate cancers. A total of 8 saRNAs for DPYSL3v1 and 14 saRNAs for DPYSL3v2 were tested in multiple prostate cancer cell lines. While none of the saRNAs significantly altered DPYSL3v1 expression, 4 saRNAs showed a strong enhancing effect on DPYSL3v2 expression, resulting in reduced cell mobility in vitro. To achieve a prostate cancer-specific delivery for in vivo testing, we conjugated the most potent saV2-9 RNA molecule with the prostate-specific membrane antigen (PSMA)-targeting aptamer A10-3.2. The conjugates successful increased DPYSL3v2 gene expression in PSMA-positive but not PSMA-negative prostate cancer cells. In nude mice bearing orthotopic xenograft of prostate cancer, a 10-day consecutive treatment with the saV2-9 conjugates significantly suppress distal metastasis compared to the control saRNAs. Analysis of xenograft tissues revealed that DPYSL3v2 expression was largely increased in saV2-9 conjugate-treated group compared to the control group. In conclusion, DPYSL3v2 promoter-targeted saRNA molecules might be used as an adjunctive therapy to suppress prostate cancer metastasis.

Polymeric nanoparticles: the future of nanomedicine

Polymeric nanoparticles (NPs) are one of the most studied organic strategies for nanomedicine. Intense interest lies in the potential of polymeric NPs to revolutionize modern medicine. To determine the ideal nanosystem for more effective and distinctly targeted delivery of therapeutic applications, particle size, morphology, material choice, and processing techniques are all research areas of interest. Utilizations of polymeric NPs include drug delivery techniques such as conjugation and entrapment of drugs, prodrugs, stimuli-responsive systems, imaging modalities, and theranostics. Cancer, neurodegenerative disorders, and cardiovascular diseases are fields impacted by NP technologies that push scientific boundaries to the leading edge of transformative advances for nanomedicine.

Genetic Engineering of Mesenchymal Stem Cells for Regenerative Medicine

Mesenchymal stem cells (MSCs), which can be obtained from various organs and easily propagated in vitro, are one of the most extensively used types of stem cells and have been shown to be efficacious in a broad set of diseases. The unique and highly desirable properties of MSCs include high migratory capacities toward injured areas, immunomodulatory features, and the natural ability to differentiate into connective tissue phenotypes. These phenotypes include bone and cartilage, and these properties predispose MSCs to be therapeutically useful. In addition, MSCs elicit their therapeutic effects by paracrine actions, in which the metabolism of target tissues is modulated. Genetic engineering methods can greatly amplify these properties and broaden the therapeutic capabilities of MSCs, including transdifferentiation toward diverse cell lineages. However, cell engineering can also affect safety and increase the cost of therapy based on MSCs; thus, the advantages and disadvantages of these procedures should be discussed. In this review, the latest applications of genetic engineering methods for MSCs with regenerative medicine purposes are presented.

siRNA Lipid Nanoparticle Potently Silences Clusterin and Delays Progression When Combined with Androgen Receptor Cotargeting in Enzalutamide-Resistant Prostate Cancer

PURPOSE

Lipid nanoparticle (LNP) formulations facilitate tumor uptake and intracellular processing through an enhanced permeation and retention effect (EPR), and currently multiple products are undergoing clinical evaluation. Clusterin (CLU) is a cytoprotective chaperone induced by androgen receptor (AR) pathway inhibition to facilitate adaptive survival pathway signaling and treatment resistance. In our study, we investigated the efficacy of siRNA tumor delivery using LNP systems in an enzalutamide-resistant (ENZ-R) castration-resistant prostate cancer (CRPC) model.

EXPERIMENTAL DESIGN

Gene silencing of a luciferase reporter gene in the PC-3M-luc stable cell line was first assessed in subcutaneous and metastatic PC-3 xenograft tumors. Upon validation, the effect of LNP siRNA targeting CLU in combination with AR antisense oligonucleotides (ASO) was assessed in ENZ-R CRPC LNCaP in vitro and in vivo models.

RESULTS

LNP LUC-siRNA silenced luciferase expression in PC-3M-luc subcutaneous xenograft and metastatic models. LNP CLU-siRNA potently suppressed CLU and AR ASO-induced CLU and AKT and ERK phosphorylation in ENZ-R LNCaP cells in vitro, more potently inhibiting ENZ-R cell growth rates and increased apoptosis when compared with AR-ASO monotherapy. In subcutaneous ENZ-R LNCaP xenografts, combinatory treatment of LNP CLU-siRNA plus AR-ASO significantly suppressed tumor growth and serum PSA levels compared with LNP LUC-siRNA (control) and AR-ASO.

CONCLUSIONS

LNP siRNA can silence target genes in vivo and enable inhibition of traditionally non-druggable genes like CLU and other promising cotargeting approaches in ENZ-R CRPC therapeutics.

Targeting tumor vasculature with aptamer-functionalized doxorubicin-polylactide nanoconjugates for enhanced cancer therapy

An A10 aptamer (Apt)-functionalized, sub-100 nm doxorubicin-polylactide (Doxo-PLA) nanoconjugate (NC) with controlled release profile was developed as an intravenous therapeutic strategy to effectively target and cytoreduce canine hemangiosarcoma (cHSA), a naturally occurring solid tumor malignancy composed solely of tumor-associated endothelium. cHSA consists of a pure population of malignant endothelial cells expressing prostate-specific membrane antigen (PSMA) and is an ideal comparative tumor model system for evaluating the specificity and feasibility of tumor-associated endothelial cell targeting by A10 Apt-functionalized NC (A10 NC). In vitro, A10 NCs were selectively internalized across a panel of PSMA-expressing cancer cell lines, and when incorporating Doxo, A10 Doxo-PLA NCs exerted greater cytotoxic effects compared to nonfunctionalized Doxo-PLA NCs and free Doxo. Importantly, intravenously delivered A10 NCs selectively targeted PSMA-expressing tumor-associated endothelial cells at a cellular level in tumor-bearing mice and dramatically increased the uptake of NCs by endothelial cells within the local tumor microenvironment. By virtue of controlled drug release kinetics and selective tumor-associated endothelial cell targeting, A10 Doxo-PLA NCs possess a desirable safety profile in vivo, being well-tolerated following high-dose intravenous infusion in mice, as supported by the absence of any histologic organ toxicity. In cHSA-implanted mice, two consecutive intravenous infusions of A10 Doxo-PLA NCs exerted rapid and substantial cytoreductive activities within a period of 7 days, resulting in greater than 70% reduction in macroscopic tumor-associated endothelial cell burden as a consequence of enhanced cell death and necrosis.

Nanomicellar TGX221 blocks xenograft tumor growth of prostate cancer in nude mice

BACKGROUND

Combination of androgen ablation along with early detection and surgery has made prostate cancer highly treatable at the initial stage. However, this cancer remains the second leading cause of cancer death among American men due to castration-resistant progression, suggesting that novel therapeutic agents are urgently needed for this life-threatening condition. Phosphatidylinositol 3-kinase p110β is a major cellular signaling molecule and has been identified as a critical factor in prostate cancer progression. In a recent report, we established a nanomicelle-based strategy to deliver p110β-specific inhibitor TGX221 to prostate cancer cells by conjugating the surface of nanomicelles with a RNA aptamer against prostate specific membrane antigen (PSMA) present in all clinical prostate cancers. In this study, we tested this nanomicellar TGX221 for its in vivo anti-tumor effect in mouse xenograft models.

METHODS

Prostate cancer cell lines LAPC-4, LNCaP, C4-2 and 22RV1 were used to establish subcutaneous xenograft tumors in nude mice. Paraffin sections from xenograft tumor specimens were used in immunohistochemistry assays to detect AKT phosphorylation, cell proliferation marker Ki67 and proliferating cell nuclear antigen (PCNA), as well as 5-bromo-2-deoxyuridine (BrdU) incorporation. Quantitative PCR assay was conducted to determine prostate-specific antigen (PSA) gene expression in xenograft tumors.

RESULTS

Although systemic delivery of unconjugated TGX221 significantly reduced xenograft tumor growth in nude mice compared to solvent control, the nanomicellar TGX221 conjugates completely blocked tumor growth of xenografts derived from multiple prostate cancer cell lines. Further analyses revealed that AKT phosphorylation and cell proliferation indexes were dramatically reduced in xenograft tumors received nanomicellar TGX221 compared to xenograft tumors received unconjugated TGX221 treatment. There was no noticeable side effect by gross observation or at microscopic level of organ tissue section.

CONCLUSION

These data strongly suggest that prostate cancer cell-targeted nanomicellar TGX221 is an effective anti-cancer agent for prostate cancer.

Aptamer nanomedicine for cancer therapeutics: barriers and potential for translation

Aptamer nanomedicine, including therapeutic aptamers and aptamer nanocomplexes, is beginning to fulfill its potential in both clinical trials and preclinical studies. Especially in oncology, aptamer nanomedicine may perform better than conventional or antibody-based chemotherapeutics due to specificity compared to the former and stability compared to the latter. Many proof-of-concept studies on applying aptamers to drug delivery, gene therapy, and cancer imaging have shown promising efficacy and impressive safety in vivo toward translation. Yet, there remains ample room for improvement and critical barriers to be addressed. In this review, we will first introduce the recent progress in clinical trials of aptamer nanomedicine, followed by a discussion of the barriers at the design and in vivo application stages. We will then highlight recent advances and engineering strategies proposed to tackle these barriers. Aptamer cancer nanomedicine has the potential to address one of the most important healthcare issues of the society.

Generation 2.5 antisense oligonucleotides targeting the androgen receptor and its splice variants suppress enzalutamide-resistant prostate cancer cell growth

PURPOSE

Enzalutamide (ENZ) is a potent androgen receptor (AR) antagonist with activity in castration-resistant prostate cancer (CRPC); however, progression to ENZ-resistant (ENZ-R) CRPC frequently occurs with rising serum PSA levels, implicating AR full-length (ARFL) or variants (AR-Vs) in disease progression.

EXPERIMENTAL DESIGN

To define functional roles of ARFL and AR-Vs in ENZ-R CRPC, we designed 3 antisense oligonucleotides (ASO) targeting exon-1, intron-1, and exon-8 in AR pre-mRNA to knockdown ARFL alone or with AR-Vs, and examined their effects in three CRPC cell lines and patient-derived xenografts.

RESULTS

ENZ-R-LNCaP cells express high levels of both ARFL and AR-V7 compared with CRPC-LNCaP; in particular, ARFL levels were approximately 12-fold higher than AR-V7. Both ARFL and AR-V7 are highly expressed in the nuclear fractions of ENZ-R-LNCaP cells even in the absence of exogenous androgens. In ENZ-R-LNCaP cells, knockdown of ARFL alone, or ARFL plus AR-Vs, similarly induced apoptosis, suppressed cell growth and AR-regulated gene expression, and delayed tumor growth in vivo. In 22Rv1 cells that are inherently ENZ-resistant, knockdown of both ARFL and AR-Vs more potently suppressed cell growth, AR transcriptional activity, and AR-regulated gene expression than knockdown of ARFL alone. Exon-1 AR-ASO also inhibited tumor growth of LTL-313BR patient-derived CRPC xenografts.

CONCLUSIONS

These data identify the AR as an important driver of ENZ resistance, and while the contributions of ARFL and AR-Vs can vary across cell systems, ARFL is the key driver in the ENZ-R LNCaP model. AR targeting strategies against both ARFL and AR-Vs is a rational approach for AR-dependent CRPC.

Cell-type-specific, Aptamer-functionalized Agents for Targeted Disease Therapy

One hundred years ago, Dr. Paul Ehrlich popularized the "magic bullet" concept for cancer therapy in which an ideal therapeutic agent would only kill the specific tumor cells it targeted. Since then, "targeted therapy" that specifically targets the molecular defects responsible for a patient's condition has become a long-standing goal for treating human disease. However, safe and efficient drug delivery during the treatment of cancer and infectious disease remains a major challenge for clinical translation and the development of new therapies. The advent of SELEX technology has inspired many groundbreaking studies that successfully adapted cell-specific aptamers for targeted delivery of active drug substances in both in vitro and in vivo models. By covalently linking or physically functionalizing the cell-specific aptamers with therapeutic agents, such as siRNA, microRNA, chemotherapeutics or toxins, or delivery vehicles, such as organic or inorganic nanocarriers, the targeted cells and tissues can be specifically recognized and the therapeutic compounds internalized, thereby improving the local concentration of the drug and its therapeutic efficacy. Currently, many cell-type-specific aptamers have been developed that can target distinct diseases or tissues in a cell-type-specific manner. In this review, we discuss recent advances in the use of cell-specific aptamers for targeted disease therapy, as well as conjugation strategies and challenges.

Hydrophobic poly (amino acid)-modified PEI-mediated delivery of single-chain antibody scFv1C9 inhibits HepG2 cell cycle process and xenograft growth in nude mice

The safe and effective gene delivery vector remains the key step for gene therapy. Hydrophobic-modified Phe-PEI (PP80) was exhibited in advantage with biocompatibility and gene delivery with smaller size and easier penetration into cells and tissues. PP80 delivery of rev-casp-3 gene was demonstrated effectively to inhibit HeLa xenograft growth in our previous work. However, it was necessary to evaluate its applicability in other cells or tissues as gene carrier. Here, we quantitatively optimized the complex ratio of PP80 and plasmid DNA (pDNA) and evaluated the potential pyrogenicity by rabbit pyrogen test. In addition, PP80-mediated expression of scFv1C9 gene blocked HepG2 cell cycle progress in vitro. Subsequently, PP80-scFv1C9 was injected into HepG2 xenograft and significantly inhibited the xenograft growth in nude mice. Further investigation indicated that PP80 was an effective gene carrier and possible for entering hepatic xenograft. These features of PP80 made it attractive as a potential gene carrier for cancer therapy.

Polymer nanoparticles for drug and small silencing RNA delivery to treat cancers of different phenotypes

Advances in nanotechnology have provided powerful and efficient tools in the development of cancer diagnosis and therapy. There are numerous nanocarriers that are currently approved for clinical use in cancer therapy. In recent years, biodegradable polymer nanoparticles have attracted a considerable attention for their ability to function as a possible carrier for target-specific delivery of various drugs, genes, proteins, peptides, vaccines, and other biomolecules in humans without much toxicity. This review will specifically focus on the recent advances in polymer-based nanocarriers for various drugs and small silencing RNA's loading and delivery to treat different types of cancer.

Identification of RNA aptamers that internalize into HPV-16 E6/E7 transformed tonsillar epithelial cells

Human papillomavirus type 16 (HPV-16) associated oropharyngeal cancers are on a significant increase and better therapeutic strategies are needed. The HPV-16 oncogenes E6 and E7 are expressed in HPV-associated cancers and are able to transform human tonsillar epithelial cells (HTECs). We used cell-Systematic Evolution of Ligands by Exponential Enrichment (SELEX) to select for RNA aptamers that entered into HPV-16 E6/E7-HTECs. After 12 rounds of cell-SELEX, a pool of aptamers was obtained that had significantly greater internalization capacity (~5-fold) into E6/E7-HTECs as compared to primary HTECs or fibroblasts. Analysis of individual aptamers from the pool indicated variable internalization into E6/E7-HTECs (1-8-fold as compared to a negative control). Most of the individual aptamers internalized into E6/E7 and primary HTECs with similar efficiency, while one aptamer exhibited ~3-fold better internalization into E6/E7-HTECs. Aptamers that internalize into cells may be useful for delivering therapeutic agents to HPV-16 associated malignancies.

Multifunctional nanoscale strategies for enhancing and monitoring blood vessel regeneration

Nanomedicine has great potential in biomedical applications, and specifically in regenerative medicine and vascular tissue engineering. Designing nanometer-sized therapeutic and diagnostic devices for tissue engineering applications is critical because cells experience and respond to stimuli on this spatial scale. For example, nanoscaffolds, including nanoscalestructured or nanoscale surface-modified vascular scaffolds, can influence cell alignment, adhesion, and differentiation to promote better endothelization. Furthermore, nanoscale contrast agents can be extended to the field of biomedical imaging to monitor and track stem cells to better understand the process of neovascularization. In addition, nanoscale systems capable of delivering biomolecules (e.g. peptides and angiogenic genes/proteins) can influence cell behavior, function, and phenotype to promote blood vessel regeneration. This review will focus on nanomedicine and nanoscale strategies applied to vascular tissue engineering. In particular, some of the latest research and potential applications pertaining to nanoscaffolds, biomedical imaging and cell tracking using nanoscale contrast agents, and nanodelivery systems of bioactive molecules applied to blood vessel regeneration will be discussed. In addition, the overlap between these three areas and their synergistic effects will be examined as related to vascular tissue engineering.

Current progress of RNA aptamer-based therapeutics

Aptamers are single-stranded nucleic acids that specifically recognize and bind tightly to their cognate targets due to their stable three-dimensional structure. Nucleic acid aptamers have been developed for various applications, including diagnostics, molecular imaging, biomarker discovery, target validation, therapeutics, and drug delivery. Due to their high specificity and binding affinity, aptamers directly block or interrupt the functions of target proteins making them promising therapeutic agents for the treatment of human maladies. Additionally, aptamers that bind to cell surface proteins are well suited for the targeted delivery of other therapeutics, such as conjugated small interfering RNAs (siRNA) that induce RNA interference (RNAi). Thus, aptamer-siRNA chimeras may offer dual-functions, in which the aptamer inhibits a receptor function, while the siRNA internalizes into the cell to target a specific mRNA. This review focuses on the current progress and therapeutic potential of RNA aptamers, including the use of cell-internalizing aptamers as cell-type specific delivery vehicles for targeted RNAi. In particular, we discuss emerging aptamer-based therapeutics that provide unique clinical opportunities for the treatment various cancers and neurological diseases.