Advances in targeting the folate receptor in the treatment/imaging of cancers

Guiding Drugs to Target-Harboring Organelles: Stretching Drug-Delivery to a Higher Level of Resolution

The ratio between the dose of drug required for optimal efficacy and the dose that causes toxicity is referred to as the therapeutic window. This ratio can be increased by directing the drug to the diseased tissue or pathogenic cell. For drugs targeting fungi and malignant cells, the therapeutic window can be further improved by increasing the resolution of drug delivery to the specific organelle that harbors the drug's target. Organelle targeting is challenging and is, therefore, an under-exploited strategy. Here we provide an overview of recent advances in control of the subcellular distribution of small molecules with the focus on chemical modifications. Highlighted are recent examples of active and passive organelle-specific targeting by incorporation of organelle-directing molecular determinants or by chemical modifications of the pharmacophore. The outstanding potential that lies in the development of organelle-specific drugs is becoming increasingly apparent.

Enhancement of Binding Affinity of Folate to Its Receptor by Peptide Conjugation

(1) Background: The folate receptor (FR) is a target for cancer treatment and detection. Expression of the FR is restricted in normal cells but overexpressed in many types of tumors. Folate was conjugated with peptides for enhancing binding affinity to the FR. (2) Materials and Methods: For conjugation, folate was coupled with propargyl or dibenzocyclooctyne, and 4-azidophenylalanine was introduced in peptides for “click” reactions. We measured binding kinetics including the rate constants of association (k_a) and dissociation (k_d) of folate-peptide conjugates with purified FR by biolayer interferometry. After optimization of the conditions for the click reaction, we successfully conjugated folate with designed peptides. (3) Results: The binding affinity, indicated by the equilibrium dissociation constant (K_D), of folate toward the FR was enhanced by peptide conjugation. The enhanced FR binding affinity by peptide conjugation is a result of an increase in the number of interaction sites. (4) Conclusion: Such peptide-ligand conjugates will be important in the design of ligands with higher affinity. These high affinity ligands can be useful for targeted drug delivery system.

Dual Drugs Anticancer Nanoformulation using Graphene Oxide-PEG as Nanocarrier for Protocatechuic Acid and Chlorogenic Acid

BACKGROUND

The chemotherapy of cancer has been complicated by poor bioavailability, adverse side effects, high dose requirement, drug resistance and low therapeutic indices. Cancer cells have different ways to inhibit the chemotherapeutic drugs, use of dual/multiple anticancer agents may be achieve better therapeutic effects in particular for drug resistant tumors. Designing a biocompatible delivery system, dual or multiple drugs could addressing these chemotherapy drawbacks and it is the focus of many current biomedical research.

METHODS

In the present study, graphene oxide-polyethylene glycol (GOPEG) nanocarrier is designed and loaded with two anticancer drugs; Protocatechuic acid (PCA) and Chlorogenic acid (CA). The designed anticancer nanocomposite was further coated with folic acid to target the cancer cells, as their surface membranes are overexpressed with folate receptors.

RESULTS

The particle size distribution of the designed nanocomposite was found to be narrow, 9-40 nm. The release profiles of the loaded drugs; PCA and CA was conducted in human body simulated PBS solutions of pH 7.4 (blood pH) and pH 4.8 (intracellular lysosomal pH). Anticancer properties were evaluated against cancerous cells i.e. liver cancer, HEPG2 and human colon cancer, HT-29 cells. The cytocompatbility was assessed on normal 3T3 fibroblasts cells.

CONCLUSION

The size of the final designed anticancer nanocomposite formulation, GOPEG-PCACA-FA was found to be distributed at 9-40 nm with a median of 8 nm. The in vitro release of the drugs PCA and CA was found to be of sustained manner which took more than 100 h for the release. Furthermore, the designed formulation was biocompatible with normal 3T3 cells and showed strong anticancer activity against liver and colon cancer cells.

Multifunctional titanium phosphate nanoparticles for site-specific drug delivery and real-time therapeutic efficacy evaluation

Receptor-targeted delivery systems have been proposed as means of concentrating therapeutic agents to improve therapeutic effects on disease sites and reduce side effects on normal issues. Herein, we synthesized biocompatible folic acid (FA)-functionalized DHE-modified TiP (TiP-PAH-DHE-FA) nanoparticles as a drug delivery system that possessed high drug loading capability and enhanced folate-receptor-mediated cellular uptake. Moreover, it also allowed drug effect evaluation based on the real-time monitoring of the fluorescence intensity of HE molecules that are triggered by intercellular ROS. This acquired drug delivery system provided a novel platform to integrate efficient cell-specific drug delivery with real-time monitoring of therapeutic efficacy.

Development of miRNA-based therapeutic approaches for cancer patients

Over the past few decades, siRNA and miRNA have attracted a great deal of attention from researchers and clinicians. These molecules have been extensively studied from the standpoint of developing biopharmaceuticals against various diseases, including heart disease, diabetes and cancers. siRNA suppresses only a single target, whereas each miRNA regulates the expression of multiple target genes. More importantly, because miRNA are also secreted from cancer cells, and their aberrant expression is associated with tumor development and progression, they represent not only therapeutic targets but also promising biomarkers for diagnosis and prognosis. Therefore, miRNA may be more effective tools against cancers, in which multiple signal pathways are dysregulated. In this review, we summarize recent progress in the development of miRNA therapeutics for the treatment of cancer patients, and describe delivery systems for oligonucleotide therapeutics.

Neutrophil Elastase Promotes Linker Cleavage and Paclitaxel Release from an Integrin-Targeted Conjugate

This work takes advantage of one of the hallmarks of cancer, that is, the presence of tumor infiltrating cells of the immune system and leukocyte-secreted enzymes, to promote the activation of an anticancer drug at the tumor site. The peptidomimetic integrin ligand cyclo(DKP-RGD) was found to accumulate on the surface of αv β3 integrin-expressing human renal cell carcinoma 786-O cells. The ligand was conjugated to the anticancer drug paclitaxel through a Asn-Pro-Val (NPV) tripeptide linker, which is a substrate of neutrophil-secreted elastase. In vitro linker cleavage assays and cell antiproliferative experiments demonstrate the efficacy of this tumor-targeting conjugate, opening the way to potential therapeutic applications.

Current Trends in Cancer Nanotheranostics: Metallic, Polymeric, and Lipid-Based Systems

Theranostics has emerged in recent years to provide an efficient and safer alternative in cancer management. This review presents an updated description of nanotheranostic formulations under development for skin cancer (including melanoma), head and neck, thyroid, breast, gynecologic, prostate, and colon cancers, brain-related cancer, and hepatocellular carcinoma. With this focus, we appraised the clinical advantages and drawbacks of metallic, polymeric, and lipid-based nanosystems, such as low invasiveness, low toxicity to the surrounding healthy tissues, high precision, deeper tissue penetration, and dosage adjustment in a real-time setting. Particularly recognizing the increased complexity and multimodality in this area, multifunctional hybrid nanoparticles, comprising different nanomaterials and functionalized with targeting moieties and/or anticancer drugs, present the best characteristics for theranostics. Several examples, focusing on their design, composition, imaging and treatment modalities, and in vitro and in vivo characterization, are detailed herein. Briefly, all studies followed a common trend in the design of these theranostics modalities, such as the use of materials and/or drugs that share both inherent imaging (e.g., contrast agents) and therapeutic properties (e.g., heating or production reactive oxygen species). This rationale allows one to apparently overcome the heterogeneity, complexity, and harsh conditions of tumor microenvironments, leading to the development of successful targeted therapies.

Magnetic Drug Delivery: Where the Field Is Going

Targeted delivery of anticancer drugs is considered to be one of the pillars of cancer treatment as it could allow for a better treatment efficiency and less adverse effects. A promising drug delivery approach is magnetic drug targeting which can be realized if a drug delivery vehicle possesses a strong magnetic moment. Here, we discuss different types of magnetic nanomaterials which can be used as magnetic drug delivery vehicles, approaches to magnetic targeted delivery as well as promising strategies for the enhancement of the imaging-guided delivery and the therapeutic action.

Emerging targeted strategies for the treatment of autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a widespread genetic disease that leads to renal failure in the majority of patients. The very first pharmacological treatment, tolvaptan, received Food and Drug Administration approval in 2018 after previous approval in Europe and other countries. However, tolvaptan is moderately effective and may negatively impact a patient's quality of life due to potentially significant side effects. Additional and improved therapies are still urgently needed, and several clinical trials are underway, which are discussed in the companion paper Müller and Benzing (Management of autosomal-dominant polycystic kidney disease-state-of-the-art) Clin Kidney J 2018; 11: i2-i13. Here, we discuss new therapeutic avenues that are currently being investigated at the preclinical stage. We focus on mammalian target of rapamycin and dual kinase inhibitors, compounds that target inflammation and histone deacetylases, RNA-targeted therapeutic strategies, glucosylceramide synthase inhibitors, compounds that affect the metabolism of renal cysts and dietary restriction. We discuss tissue targeting to renal cysts of small molecules via the folate receptor, and of monoclonal antibodies via the polymeric immunoglobulin receptor. A general problem with potential pharmacological approaches is that the many molecular targets that have been implicated in ADPKD are all widely expressed and carry out important functions in many organs and tissues. Because ADPKD is a slowly progressing, chronic disease, it is likely that any therapy will have to continue over years and decades. Therefore, systemically distributed drugs are likely to lead to potentially prohibitive extra-renal side effects during extended treatment. Tissue targeting to renal cysts of such drugs is one potential way around this problem. The use of dietary, instead of pharmacological, interventions is another.

Insights on the transport of tamoxifen by gold nanoparticles for MCF-7 breast cancer cells based on SERS spectroscopy

Gold nanoparticles (AuNP) were synthesized and modified with anti-folate receptor antibody (AB), folic acid (FA), crystal violet (CV), poly (ethyleneglycol) methyl ether thiol and the antineoplastic drug tamoxifen (TAM). Such a preparation was incubated in vitro with MCF-7 human breast cancer cells, showing a decrease in the TAM dosage for the reduction of cell viability. The adsorption of TAM on gold surface was investigated by surface-enhanced Raman scattering (SERS) spectroscopy and the assignment based on Density Functional Theory calculations showed that the ether moiety was involved in the interactions with the metal. Such a chemical affinity was correlated with the carrying of TAM in the biological media. CV was included in the preparation as a molecular probe for SERS spectroscopy, whose signal was monitored to analyse the efficiency of the modified AuNP in the target of neoplastic cells. The results showed AB, FA and TAM components had complementary roles in the cell recognition and, therefore, in the efficiency of the drug carrier nanosystem.