Reductive nanocomplex encapsulation of cRGD-siRNA conjugates for enhanced targeting to cancer cells

Recent Advancements of Aptamers in Cancer Therapy

Aptamers are chemical antibodies possessing the capability of overcoming the limitations posed by conventional antibodies, particularly for diagnostic, therapeutic, and theranostic applications in cancer. The ease of chemical modifications or functionalization, including conjugations with nucleic acids, drug molecules, and nanoparticles, has made these aptamers to gain priorities in research. In this Mini-review, various reports on therapeutics with aptamer-functionalized nanomaterials for controlled or multistep drug release, targeted delivery, stimuli-responsive drug release, etc. are discussed. In the case of nucleic-acid-conjugated aptamers, DNA nanotrains and DNA beacons are discussed in terms of the possibility of multidrug loading for chemotherapy and gene therapy. Developments with electrochemical aptasensors and signal-enhanced immune aptasensors are also discussed. Further, the future scope of aptamer technology in cancer theranostics and the prevailing limitations are discussed.

Activity and Tissue Distribution of Antisense Oligonucleotide CT102 Encapsulated with Cytidinyl/Cationic Lipid against Hepatocellular Carcinoma

Insulin-like growth factor 1 receptor (IGF1R), a cell surface receptor with tyrosine kinase (TK) activity, has ligands abnormally expressed in acute leukemia, multiple myeloma, breast, prostate, cervical, and nonsmall cell lung cancers, Ewing's sarcoma, and other malignant tumors. IGF1R mediates the malignant proliferation, invasion, and metastasis of tumor cells through a variety of signal transduction pathways, and it is also involved in tumor angiogenesis and tumor cell antiapoptosis. In this study, the neutral cytidinyl lipid DNCA and cystine skeleton cationic lipid CLD from our laboratory could be optimized to encapsulate antisense oligonucleotide (ASO) CT102 to form stable and uniform Mix/CT102 nanoparticles (NPs), which could specifically target tumor cells that highly expressed IGF1R in vivo by intravenous administration. Compared with naked CT102, the lipid complex could promote the uptake and late apoptosis levels of HepG2 and Huh-7 cells, inhibiting cell proliferation efficiently. We also found that Mix/CT102 could enter nucleus in about 2 h, effectively downregulating the mRNA level of IGF1R. The in vivo efficacy experiment demonstrated that in the group that received the optimal dose of Mix/CT102, tumor volume was reduced 8-fold compared with the naked dose group. Meanwhile, in vivo distribution studies showed that the nanoparticles had a predominant accumulation capacity in liver tissue. These results indicated that clinicians can expect the Mix/CT102 nanocomposite to be very effective in reducing the dose and frequency of clinically administered CT102, thereby reducing the side effects of ASOs.

Emerging nanotechnology based combination therapies of taxanes for multiple drug-resistant cancers

'One drug- one target' to 'multiple drug- multiple targets' paradigm shifted to produce combination therapies, have found great outcomes to overcome multiple drug resistance (MDR). MDR is a significant barrier to the delivery of taxane-based anticancer medicines such as docetaxel, paclitaxel, and cabazitaxel. Due to MDR induced by drug efflux transporters, clinical application of these medications is impeded. To date, nanoformulations such as liposomes, micelles, polymeric nanoparticles, and gold nanoparticles have been investigated to deliver taxanes alone and in combination to reverse drug resistance. Despite the fact that various groups have already looked into taxane nano formulations in the literature, there isn't much in the way of polypharmacology and advanced nanoformulations with a focus on MDR. In this overview, we briefly covered the insights regarding MDR, difficulties related to current pharmaceutical products of taxanes, combination therapies of taxanes to combat MDR, all of which can be used to delve into cancer treatment.

Delivery of small interfering RNAs by nanovesicles for cancer therapy

Small interfering ribonucleic acids (siRNAs) are originally recognized as an intermediate of the RNA interference (RNAi) pathway. They can inhibit or silence various cellular pathways by knocking down specific messenger RNA molecules. In cancer cells, siRNAs can suppress the expression of several multidrug-resistant genes, leading to the increased deposition of chemotherapeutic drugs at the tumor site. siRNA therapy can be used to selectively increase apoptosis of cancer cells or activate an immune response to the cancer. However, delivering siRNAs to the targeted location is the main limitation in achieving safe and effective delivery of siRNAs. This review highlights some representative examples of nonviral delivery systems, especially nanovesicles such as exosomes, liposomes, and niosomes. Nanovesicles can improve the delivery of siRNAs by increasing their intracellular delivery, and they have demonstrated excellent potential for cancer therapy. This review focuses on recent discoveries of siRNA targets for cancer therapy and the use of siRNAs to successfully silence these targets. In addition, this review summarizes the recent progress in designing nanovesicles (liposomes or niosomes) for siRNA delivery to cancer cells and the effects of a combination of anticancer drugs and siRNA therapy in cancer therapy.

Feasibility of cRGD conjugation at 5'-antisense strand of siRNA by phosphodiester linkage extension

Small interfering RNAs (siRNAs) are widely studied for their highly specific gene silencing activity. However, obstacles remain to the clinical application of siRNAs. Attaching conjugates to siRNAs can improve their stability and broaden their application, and most functional conjugates of siRNAs locate at the 3'-terminus of the sense or antisense strand. In this work, we found that conjugating a group at the 5'-terminus of the antisense strand via phosphodiester was practicable, especially when the group was a flexible moiety such as an alkyl linker. When conjugating a bulky ligand, such as cRGD, the length of the 5'-phosphodiester linker between the ligand and the 5'-terminus of the antisense strand was the key in terms of RNA interference (RNAi). With a relative longer linker, the conjugates showed potency similar to siRNA. A highly efficient transfection system composed of a neutral cytidinyl lipid (DNCA) and a gemini-like cationic lipid (CLD) was employed to deliver siRNAs or their conjugates. The cRGD conjugates showed superior targeting delivery and antitumor efficacy in vivo and also selective cellular uptake in vitro. This unity of encapsulation and conjugation strategy may provide potential strategies for siRNA-based gene therapy.

Functionalized selenium nanoparticles for targeted siRNA delivery silence Derlin1 and promote antitumor efficacy against cervical cancer

Small interfering RNA (siRNA) exhibits great potential as a novel therapeutic option due to its highly sequence-specific ability to silence genes. However, efficient and safe delivery carriers are required for developing novel therapeutic paradigms. Thus, the successful development of efficient delivery platforms for siRNA is a crucial issue for the development of siRNA-based drugs in cancer treatments. In this study, biocompatible selenium nanoparticles (SeNPs) were loaded with RGDfC peptide to fabricate tumor-targeting gene delivery vehicle RGDfC-SeNPs. Subsequently, RGDfC-SeNPs were loaded with Derlin1-siRNA to fabricate RGDfC-Se@siRNA, which are functionalized selenium nanoparticles. RGDfC-Se@siRNA showed greater uptake in HeLa cervical cancer cells in comparison with that in human umbilical vein endothelial cells (HUVECs), verifying the RGDfC-mediated specific uptake of RGDfC-Se@siRNA. RGDfC-Se@siRNA was capable of entering HeLa cells via clathrin-associated endocytosis, and showed faster siRNA release in a cancer cell microenvironment in comparison with a normal physiological environment. qPCR and western blotting assays both indicated that RGDfC-Se@siRNA exhibited an obvious gene silencing efficacy in HeLa cells. RGDfC-Se@siRNA suppressed the invasion, migration and the proliferation of HeLa cells, and triggered HeLa cell apoptosis. Moreover, RGDfC-Se@siRNA induced the disruption of mitochondrial membrane potentials. Meanwhile, RGDfC-Se@siRNA enhanced the generation of reactive oxygen species (ROS) in HeLa cell, suggesting that mitochondrial dysfunction mediated by ROS might play a significant role in RGDfC-Se@siRNA-induced apoptosis. Interestingly, RGDfC-SeNPs@siRNA exhibited significant antitumor activity in a HeLa tumor-bearing mouse model. Additionally, RGDfC-SeNPs@siRNA is nontoxic to main organ of mouse. The above results indicate that RGDfC-Se@siRNA provides a promising potential for cervical cancer therapy.

Disulfide bridge as a linker in nucleic acids' bioconjugation. Part II: A summary of practical applications

Disulfide conjugation invariably remains a key tool in research on nucleic acids. This versatile and cost-effective method plays a crucial role in structural studies of DNA and RNA as well as their interactions with other macromolecules in a variety of biological systems. In this article we review applications of disulfide-bridged conjugates of oligonucleotides with other (bio)molecules such as peptides, proteins etc. and present key findings obtained with their help.

Construction of a Targeting Nanoparticle of 3',3″-Bis-Peptide-siRNA Conjugate/Mixed Lipid with Postinserted DSPE-PEG2000-cRGD

The cyclic Arg-Gly-Asp (cRGD) peptides are widely used as tumor-targeting ligands due to their specific binding ability to integrin α_vβ₃, which is overexpressed on the surface of various cancer cells and the endothelial cells of new blood vessels within tumor tissues. In this paper, the postinsertion strategy of DSPE-PEG2000-cRGD has been applied to the nanoparticles of 3',3″-bis-peptide-siRNA (pp-siRNA) encapsulated by gemini-like cationic lipid (CLD) and neutral cytosin-1-yl lipid (DNCA) from our lab. It was confirmed that the nanoparticles of pp-siRNA/CLD/DNCA/DSPE-PEG2000-cRGD (PCNR) were able to specifically target tumor cells with highly expressed integrin α_vβ₃; moreover, it efficiently downregulated the levels of BRAF mRNA and the BRAF protein and inhibited cell proliferation in A375 cells, in comparison with the nontargeted nanocomplex of pp-siRNA/CLD/DNCA/cRAD (PCNA). The uptake pathways of PCNR are mostly dependent on CvME-mediated endocytosis and macropinocytosis in A375 cells, which could bypass lysosome or quickly lead to the lysosomal escape to reduce siRNA degradation. Finally, the biodistribution study showed that PCNR exhibited a high ability to accumulate in tumor tissues. These results suggest that the nanocomplex of PCNR is promising to be highly effective in the treatment of melanomas including their mutation.

Current Transport Systems and Clinical Applications for Small Interfering RNA (siRNA) Drugs

Small interfering RNAs (siRNAs) are an attractive new agent with potential as a therapeutic tool because of its ability to inhibit specific genes for many conditions, including viral infections and cancers. However, despite this potential, many challenges remain, including off-target effects, difficulties with delivery, immune responses, and toxicity. Traditional genetic vectors do not guarantee that siRNAs will silence genes in vivo. Rational design strategies, such as chemical modification, viral vectors, and non-viral vectors, including cationic liposomes, polymers, nanocarriers, and bioconjugated siRNAs, provide important opportunities to overcome these challenges. We summarize the results of research into vector delivery of siRNAs as a therapeutic agent from their design to clinical trials in ophthalmic diseases, cancers, respiratory diseases, and liver virus infections. Finally, we discuss the current state of siRNA delivery methods and the need for greater understanding of the requirements.

Current Aspects of siRNA Bioconjugate for In Vitro and In Vivo Delivery

Studies on siRNA delivery have seen intense growth in the past decades since siRNA has emerged as a new class of gene therapeutics for the treatment of various diseases. siRNA bioconjugate, as one of the major delivery strategies, offers the potential to enhance and broaden pharmacological properties of siRNA, while minimizing the heterogeneity and stability-correlated toxicology. This review summarizes the recent developments of siRNA bioconjugate, including the conjugation with antibody, peptide, aptamer, small chemical, lipidoid, cell-penetrating peptide polymer, and nanoparticle. These siRNA bioconjugate, either administrated alone or formulated with other agents, could significantly improve pharmacokinetic behavior, enhance the biological half-life, and increase the targetability while maintaining sufficient gene silencing activity, with a concomitant improvement of the therapeutic outcomes and diminishment of adverse effects. This review emphasizes the delivery application of these siRNA bioconjugates, especially the conjugation strategy that control the integrity, stability and release of siRNA bioconjugates. The limitations conferred by these conjugation strategies have also been covered.

RGD peptide-modified, paclitaxel prodrug-based, dual-drugs loaded, and redox-sensitive lipid-polymer nanoparticles for the enhanced lung cancer therapy

One approach to improve the targeted therapeutic efficiency of lung cancer is to deliver drugs using nano-scaled systems. In this study, RGD peptide-modified, paclitaxel (PTX) prodrug-based, dual-drugs loaded, and redox-sensitive lipid-polymer nanoparticles were developed and the in vitro and in vivo antitumor efficiency was evaluated in lung cancer cells and tumor bearing animal models. RGD-modified PTX and cisplatin (CDDP) loaded LPNs (RGD-ss-PTX/CDDP LPNs) have sizes around 190 nm, and zeta potentials of -35 mV. The half-maximal inhibitory concentration (IC50) values were 26.7 and 75.3 μg/mL for drugs loaded LPNs and free drugs combination, which indicates significantly higher antitumor activity of LPNs than free drugs. RGD-ss-PTX/CDDP LPNs also exhibited the best antitumor efficiency in vivo, which inhibited the tumor size of mice from 1486 mm³ to 263 mm³. The results illustrated that the system could successfully load drugs and achieve synergistic combination lung cancer treatment efficiency with lower systemic toxicity compared with free drugs counterparts. The resulting system could be facilitated as a promising targeted nanomedicine for the treatment of lung cancer.