Efficient Synthetic Approach to Linear Dasatinib-DNA Conjugates by Click Chemistry

Drug-Grafted DNA for Cancer Therapy

With the development of solid-phase synthesis and DNA nanotechnology, DNA-based drug delivery systems have seen large advancements over the past decades. By combining various drugs (small-molecular drugs, oligonucleotides, peptides, and proteins) with DNA technology, drug-grafted DNA has demonstrated great potential as a promising platform in recent years, in which complementary properties of both components have been discovered; for instance, the synthesis of amphiphilic drug-grafted DNA has enabled the production of DNA nanomedicines for gene therapy and chemotherapy. Through the design of linkages between drug and DNA parts, stimuli-responsiveness can be instilled, which has boosted the application of drug-grafted DNA in various biomedical applications such as cancer therapy. This review discusses the progress of various drug-grafted DNA therapeutic agents, exploring the synthetic techniques and anticancer applications afforded through the combination of drug and nucleic acids.

Nanotechnology of Tyrosine Kinase Inhibitors in Cancer Therapy: A Perspective

Nanotechnology is an important application in modern cancer therapy. In comparison with conventional drug formulations, nanoparticles ensure better penetration into the tumor mass by exploiting the enhanced permeability and retention effect, longer blood circulation times by a reduced renal excretion and a decrease in side effects and drug accumulation in healthy tissues. The most significant classes of nanoparticles (i.e., liposomes, inorganic and organic nanoparticles) are here discussed with a particular focus on their use as delivery systems for small molecule tyrosine kinase inhibitors (TKIs). A number of these new compounds (e.g., Imatinib, Dasatinib, Ponatinib) have been approved as first-line therapy in different cancer types but their clinical use is limited by poor solubility and oral bioavailability. Consequently, new nanoparticle systems are necessary to ameliorate formulations and reduce toxicity. In this review, some of the most important TKIs are reported, focusing on ongoing clinical studies, and the recent drug delivery systems for these molecules are investigated.

TrkC-Targeted Kinase Inhibitors And PROTACs

A small molecule motif (IY-IY), which binds the tropomyosin receptor kinase C (TrkC), was used to deliver the promiscuous kinase inhibitor (KI) dasatinib into breast cancer. Conjugates with noncleavable (1) and cleavable (2) linkers were compared in cellular assays and shown to have more impact on the cell viabilities of TrkC⁺ breast cancer cells over TrkC^- epithelial cells. The IY-IY fragment was also used to recruit the E3 ligase cereblon, giving a potent proteolysis targeting chimeric (PROTAC) for TrkC degradation in metastatic breast cancer cells.

Drug "Clicking" on Cell-Penetrating Fluorescent Nanoparticles for In Cellulo Chemical Proteomics

Chemical proteomics approaches are widely used to identify molecular targets of existing or novel drugs. This manuscript describes the development of a straightforward approach to conjugate azide-labeled drugs via click chemistry to alkyne-tagged cell-penetrating fluorescent nanoparticles as a novel tool to study target engagement and/or identification inside living cells. A modification of the Baeyer test for alkynes allows monitoring the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, guaranteeing the presence of the drug on the solid support. As a proof of concept, the conjugation of the promiscuous kinase inhibitor dasatinib to Cy5-labeled nanoparticles is presented. Dasatinib-decorated fluorescent nanoparticles efficiently inhibited its protein target SRC in vitro, entered cancer cells, and colocalized with SRC in cellulo.

SN-38 Conjugated Gold Nanoparticles Activated by Ewing Sarcoma Specific mRNAs Exhibit In Vitro and In Vivo Efficacy

The limited delivery of chemotherapy agents to cancer cells and the nonspecific action of these agents are significant challenges in oncology. We have previously developed a customizable drug delivery and activation system in which a nucleic acid functionalized gold nanoparticle (Au-NP) delivers a drug that is selectively activated within a cancer cell by the presence of an mRNA unique to the cancer cell. The amount of drug released from sequestration to the Au-NP is determined by both the presence and the abundance of the cancer cell specific mRNA in a cell. We have now developed this technology for the potent, but difficult to deliver, topoisomerase I inhibitor SN-38. Herein, we demonstrate both the efficient delivery and selective release of SN-38 from gold nanoparticles in Ewing sarcoma cells with resulting efficacy in vitro and in vivo. These results provide further preclinical validation for this novel cancer therapy and may be extendable to other cancers that exhibit sensitivity to topoisomerase I inhibitors.

Facile access to modified and functionalized PNAs through Ugi-based solid phase oligomerization

Peptide nucleic acids (PNAs) derivatized with functional molecules are increasingly used in diverse biosupramolecular applications. PNAs have proven to be highly tolerant to modifications and different applications benefit from the use of modified PNAs, in particular modifications at the γ position. Herein we report simple protocols to access modified PNAs from iterative Ugi couplings which allow modular modifications at the α, β or γ position of the PNA backbone from simple starting materials. We demonstrate the utility of the method with the synthesis of several bioactive small molecules (a peptide ligand, a kinase inhibitor and a glycan)-PNA conjugates.