Gold nanoparticle-siRNA mediated oncogene knockdown at RNA and protein level, with associated gene effects

The Promise of Nanoparticles-Based Radiotherapy in Cancer Treatment

Radiation has been utilized for a long time for the treatment of cancer patients. However, radiotherapy (RT) has many constraints, among which non-selectivity is the primary one. The implementation of nanoparticles (NPs) with RT not only localizes radiation in targeted tissue but also provides significant tumoricidal effect(s) compared to radiation alone. NPs can be functionalized with both biomolecules and therapeutic agents, and their combination significantly reduces the side effects of RT. NP-based RT destroys cancer cells through multiple mechanisms, including ROS generation, which in turn damages DNA and other cellular organelles, inhibiting of the DNA double-strand damage-repair system, obstructing of the cell cycle, regulating of the tumor microenvironment, and killing of cancer stem cells. Furthermore, such combined treatments overcome radioresistance and drug resistance to chemotherapy. Additionally, NP-based RT in combined treatments have shown synergistic therapeutic benefit(s) and enhanced the therapeutic window. Furthermore, a combination of phototherapy, i.e., photodynamic therapy and photothermal therapy with NP-based RT, not only reduces phototoxicity but also offers excellent therapeutic benefits. Moreover, using NPs with RT has shown promise in cancer treatment and shown excellent therapeutic outcomes in clinical trials. Therefore, extensive research in this field will pave the way toward improved RT in cancer treatment.

Simultaneous nanocarrier-mediated delivery of siRNAs and chemotherapeutic agents in cancer therapy and diagnosis: Recent advances

Recently, investigations have revealed that RNA interference (RNAi) has a remarkable potential to decrease cancer burden by downregulating genes. Among various RNAi molecules, small interfering RNA (siRNA) has been more attractive for this goal and is able to silence a target pathological path and promote the degradation of a certain mRNA, resulting in either gain or loss of function of proteins. Moreover, therapeutic siRNAs have exhibited low side effects compared to other therapeutic molecular candidates. Nevertheless, siRNA delivery has its own limitations including quick degradation in circulation, ineffective internalization and low passive uptake by cells, possible toxicity against off-target sites, and inducing unfavorable immune responses. Therefore, delivery tools must be able to specifically direct siRNAs to their target locations without inflicting detrimental effects on other sites. To conquer the mentioned problems, nanocarrier-mediated delivery of siRNAs, using inorganic nanoparticles (NPs), polymers, and lipids, has been developed as a biocompatible delivery approach. In this review, we have discussed recent advances in the siRNA delivery methods that employ nanoparticles, lipids, and polymers, as well as the inorganic-based co-delivery systems used to deliver siRNAs and anticancer agents to target cells.

Peptide generated anisotropic gold nanoparticles as efficient siRNA vectors

Based on the cell penetrating ability of tryptophan-containing peptides, eight linear hexapeptides have been designed, synthesized and explored their efficiency toward the synthesis of gold nanoparticles under sunlight. The peptide generated gold nanoparticles (LP-GNPs) have been characterized by UV-visible spectroscopy, Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS) techniques. The binding ability of LP-GNPs toward siRNA, evaluated by gel electrophoresis indicates that sequence-selective-GNPs without any surface modifications exhibit strong affinity toward negatively charged biomolecules. Cellular uptake studies suggest that LP-GNPs exhibit significant uptake of fluorescence-labeled siRNA inside the cells as evidenced from Fluorescence Microscopy. In vitro gene silencing efficiency using newly generated GNPs revealed that above mentioned LP-GNPs efficiently down-regulate the level of GAPGH gene in colon cancer cells. Comparative gene silencing efficiency results indicate that anisotropic LP7-GNPs exhibit comparable efficacy to other existing carrier systems, such as Lipofectamine 2000 in presence of serum, mimicking in-vivo system. In conclusion, our results demonstrate that peptide-GNPs based delivery system for siRNA emerges to be effective to deliver RNAi therapeutics, uncovering new avenue in oncotherapy.

GLUT1 and GLUT3 involvement in anthocyanin gastric transport- Nanobased targeted approach

Anthocyanins may protect against a myriad of human diseases. However few studies have been conducted to evaluate their bioavailability so their absorption mechanism remains unclear. This study aimed to evaluate the role of two glucose transporters (GLUT1 and GLUT3) in anthocyanins absorption in the human gastric epithelial cells (MKN-28) by using gold nanoparticles to silence these transporters. Anthocyanins were purified from purple fleshed sweet potatoes and grape skin. Silencing of GLUT1 and/or GLUT3 mRNA was performed by adding AuNP@GLUT1 and/or AuNP@GLUT3 to MKN-28 cells. Downregulation of mRNA expression occurred concomitantly with the reduction in protein expression. Malvidin-3-O-glucoside (Mv3glc) transport was reduced in the presence of either AuNP@GLUT1 and AuNP@GLUT3, and when both transporters were blocked simultaneously. Peonidin-3-(6'-hydroxybenzoyl)-sophoroside-5-glucoside (Pn3HBsoph5glc) and Peonidin-3-(6'-hydroxybenzoyl-6″-caffeoyl)-sophoroside-5-glucoside (Pn3HBCsoph5glc) were assayed to verify the effect of the sugar moiety esterification at glucose B in transporter binding. Both pigments were transported with a lower transport efficiency compared to Mv3glc, probably due to steric hindrance of the more complex structures. Interestingly, for Pn3HBCsoph5glc although the only free glucose is at C5 and the inhibitory effect of the nanoparticles was also observed, reinforcing the importance of glucose on the transport regardless of its position or substitution pattern. The results support the involvement of GLUT1 and GLUT3 in the gastric absorption of anthocyanins.

Current status and future perspectives of gold nanoparticle vectors for siRNA delivery

Discovering the vast therapeutic potential of siRNA opened up new clinical research areas focussing on a number of diseases and applications; however significant problems with siRNA stability and delivery have hindered its clinical applicability. As a result, interest in the development of practical siRNA delivery systems has grown in recent years. Of the numerous siRNA delivery strategies currently on offer, gold nanoparticles (AuNPs) stand out thanks to their biocompatibility and capacity to protect siRNA against degradation; not to mention the versatility offered by their tuneable shape, size and optical properties. Herein this review provides a complete summary of the methodologies for functionalizing AuNPs with siRNA, paying singular attention to the AuNP shape, size and surface coating, since these key factors heavily influence cellular interaction, internalization and, ultimately, the efficacy of the hybrid particle. The most noteworthy hybridization strategies have been highlighted along with the most innovative and outstanding in vivo studies with a view to increasing clinical interest in the use of AuNPs as siRNA nanocarriers.

Baptista P, Mullin M, Dalby MJ, Berry CC. Nanoparticle-antagomiR based targeting of miR-31 to induce osterix and osteocalcin expression in mesenchymal stem cells

Mesenchymal stem cells are multipotent adult stem cells capable of generating bone, cartilage and fat, and are thus currently being exploited for regenerative medicine. When considering osteogenesis, developments have been made with regards to chemical induction (e.g. differentiation media) and physical induction (e.g. material stiffness, nanotopography), targeting established early transcription factors or regulators such as runx2 or bone morphogenic proteins and promoting increased numbers of cells committing to osteo-specific differentiation. Recent research highlighted the involvement of microRNAs in lineage commitment and terminal differentiation. Herein, gold nanoparticles that confer stability to short single stranded RNAs were used to deliver MiR-31 antagomiRs to both pre-osteoblastic cells and primary human MSCs in vitro. Results showed that blocking miR-31 led to an increase in osterix protein in both cell types at day 7, with an increase in osteocalcin at day 21, suggesting MSC osteogenesis. In addition, it was noted that antagomiR sequence direction was important, with the 5 prime reading direction proving more effective than the 3 prime. This study highlights the potential that miRNA antagomiR-tagged nanoparticles offer as novel therapeutics in regenerative medicine.

Atom Transfer Radical Polymerization of Multishelled Cationic Corona for the Systemic Delivery of siRNA

We propose an effective siRNA delivery system by preparing poly(DAMA-HEMA)-multilayered gold nanoparticles using multiple surface-initiated atom transfer radical polymerization processes. The polymeric multilayer structure is characterized by transmission electron microscopy, matrix-associated laser desorption/ionization time-of-flight mass spectrometry, UV-vis spectroscopy, Fourier transform infrared spectroscopy, dynamic light scattering, and ζ-potential. The amount of siRNA electrostatically incorporated into the nanoparticle can be tuned by the number of polymeric shells, which in turn influences the cellular uptake and gene silencing effect. In a bioreductive environment, the interlayer disulfide bond breaks to release the siRNA from the degraded polymeric shells. Intravenously injected c-Myc siRNA-incorporated particles accumulate in the tumor site of a murine lung carcinoma model and significantly suppress the tumor growth. Therefore, the combination of a size-tunable AuNP core and an ATRP-functionalized shell offers control and versatility in the effective delivery of siRNA.

Biogenic selenium nanoparticles induce ROS-mediated necroptosis in PC-3 cancer cells through TNF activation

BACKGROUND

Selenium is well documented to inhibit cancer at higher doses; however, the mechanism behind this inhibition varies widely depending on the cell type and selenium species. Previously, we have demonstrated that Bacillus licheniformis JS2 derived biogenic selenium nanoparticles (SeNPs) induce non-apoptotic cell death in prostate adenocarcinoma cell line, PC-3, at a minimal concentration of 2 µg Se/ml, without causing toxicity to the primary cells. However, the mechanism behind its anticancer activity was elusive.

RESULTS

Our results have shown that these SeNPs at a concentration of 2 µg Se/ml were able to induce reactive oxygen species (ROS) mediated necroptosis in PC-3 cells by gaining cellular internalization. Real-time qPCR analysis showed increased expression of necroptosis associated tumor necrotic factor (TNF) and interferon regulatory factor 1 (IRF1). An increased expression of RIP1 protein was also observed at the translational level upon SeNP treatment. Moreover, the cell viability was significantly increased in the presence of necroptosis inhibitor, Necrostatin-1.

CONCLUSION

Data suggest that our biogenic SeNPs induce cell death in PC-3 cells by the ROS-mediated activation of necroptosis, independent to RIP3 and MLKL, regulated by a RIP1 kinase.

Powering up the molecular therapy of RNA interference by novel nanoparticles

With more suitable for disease treatment due to reduced cellular toxicity, higher loading capacity, and better biocompatibility, nanoparticle-based siRNA delivery systems have proved to be more potent, higher specific and less toxic than the traditional drug therapy.