RNAi Screening of the Glucose-Regulated Chaperones in Cancer with Self-Assembled siRNA Nanostructures

Functional Materials for Subcellular Targeting Strategies in Cancer Therapy: Progress and Prospects

Neoadjuvant and adjuvant therapies have made significant progress in cancer treatment. However, tumor adjuvant therapy still faces challenges due to the intrinsic heterogeneity of cancer, genomic instability, and the formation of an immunosuppressive tumor microenvironment. Functional materials possess unique biological properties such as long circulation times, tumor-specific targeting, and immunomodulation. The combination of functional materials with natural substances and nanotechnology has led to the development of smart biomaterials with multiple functions, high biocompatibilities, and negligible immunogenicities, which can be used for precise cancer treatment. Recently, subcellular structure-targeting functional materials have received particular attention in various biomedical applications including the diagnosis, sensing, and imaging of tumors and drug delivery. Subcellular organelle-targeting materials can precisely accumulate therapeutic agents in organelles, considerably reduce the threshold dosages of therapeutic agents, and minimize drug-related side effects. This review provides a systematic and comprehensive overview of the research progress in subcellular organelle-targeted cancer therapy based on functional nanomaterials. Moreover, it explains the challenges and prospects of subcellular organelle-targeting functional materials in precision oncology. The review will serve as an excellent cutting-edge guide for researchers in the field of subcellular organelle-targeted cancer therapy.

Nucleic acid-based artificial nanocarriers for gene therapy

Nucleic acid nanotechnology is a powerful tool in the fields of biosensing and nanomedicine owing to their high editability and easy synthesis and modification. Artificial nucleic acid nanostructures have become an emerging research hotspot as gene carriers with low cytotoxicity and immunogenicity for therapeutic approaches. In this review, recent progress in the design and functional mechanisms of nucleic acid-based artificial nano-vectors especially for exogenous siRNA and antisense oligonucleotide delivery is summarized. Different types of DNA nanocarriers, including DNA junctions, tetrahedrons, origami, hydrogels and scaffolds, are introduced. The enhanced targeting strategies to improve the delivery efficacy are demonstrated. Furthermore, RNA based gene nanocarrier systems by self-assembly of short strands, rolling circle transcription, chemical crosslinking and using RNA motifs and DNA-RNA hybrids are demonstrated. Finally, the outlook and potential challenges are highlighted. The nucleic acid-based artificial nanocarriers offer a promising and precise tool for gene delivery and therapy.

HSP70s in Breast Cancer: Promoters of Tumorigenesis and Potential Targets/Tools for Therapy

The high frequency of breast cancer worldwide and the high mortality among women with this malignancy are a serious challenge for modern medicine. A deeper understanding of the mechanisms of carcinogenesis and emergence of metastatic, therapy-resistant breast cancers would help development of novel approaches to better treatment of this disease. The review is dedicated to the role of members of the heat shock protein 70 subfamily (HSP70s or HSPA), mainly inducible HSP70, glucose-regulated protein 78 (GRP78 or HSPA5) and GRP75 (HSPA9 or mortalin), in the development and pathogenesis of breast cancer. Various HSP70-mediated cellular mechanisms and pathways which contribute to the oncogenic transformation of mammary gland epithelium are reviewed, as well as their role in the development of human breast carcinomas with invasive, metastatic traits along with the resistance to host immunity and conventional therapeutics. Additionally, intracellular and cell surface HSP70s are considered as potential targets for therapy or sensitization of breast cancer. We also discuss a clinical implication of Hsp70s and approaches to targeting breast cancer with gene vectors or nanoparticles downregulating HSP70s, natural or synthetic (small molecule) inhibitors of HSP70s, HSP70-binding antibodies, HSP70-derived peptides, and HSP70-based vaccines.

Bifunctional Au-templated RNA nanoparticles enable direct cell uptake detection and GRP75 knockdown in prostate cancer

Nucleic acids templated on gold (Au) surfaces have led to a wide range of functional materials ranging from microarrays, sensors and probes in addition to drug delivery and treatment. In this application, we describe a simple and novel method for templating amino-functionalized RNA onto Au surfaces and their self-assembly into small, discrete nanoparticles. In our method, sample hybridization with a complementary RNA strand with and without a fatty acid (palmitamide) appendage produced functionalized double-stranded RNA on the Au surface. The resulting Au-functionalized RNA particles were found to be stable under reducing conditions according to UV-Vis spectroscopy. Sample characterization by DLS and TEM confirmed self-assembly into primarily small (∼10-40 nm) spherical shaped nanoparticles expected to be amenable to cell biology. However, fluorescence emission (λexc: 350 nm, λem: 650 nm) revealed radiative properties which limited cell uptake detection. Introduction of FITC within the Au-functionalized RNA particles produced a bifunctional probe, in which FITC fluorescence emission (λexc: 494 nm, λem: 522 nm) facilitated cell uptake detection, in a time-dependent manner. The dual encapsulation-release profiles of the FITC-labeled Au-functionalized RNA particles were validated by time-dependent UV-Vis spectroscopy and spectrofluorimetry. These experiments respectively indicated an increase in FITC absorption (λabs: 494 nm) and fluorescence emission (λem: 522 nm) with increased sample incubation times, under physiological conditions. The release of Au-functionalized siRNA particles in prostate cancer (PC-3) cells resulted in concomitant knockdown of GRP75, which led to detectable levels of cell death in the absence of a transfection vector. Thus, the formulation of stable, small and discrete Au-functionalized RNA nanoparticles may prove to be valuable bifunctional probes in the theranostic study of cancer cells.

Size Matters: Arginine-Derived Peptides Targeting the PSMA Receptor Can Efficiently Complex but Not Transfect siRNA

Oligoarginine sequences conjugated to a short cancer-targeting peptide (CTP) selective for the prostate-specific membrane antigen (PSMA) receptor was developed for selective small interfering RNA (siRNA) delivery to a human metastatic/castration-resistant prostate cancer (PCa) cell line, which expresses PSMA on the surface. The PSMA-Rn (n = 6 and 9) peptides were synthesized by solid-phase peptide synthesis, characterized by liquid chromatography-mass spectrometry (LC-MS) and condensed with glucose-regulated protein (GRP)-silencing siRNAs. Native gels showed formation of stable CTP:siRNA ionic complexes. Furthermore, siRNA release was effected by heparin competition, supporting the peptides' capabilities to act as condensing and releasing agents. However, dynamic light scattering (DLS) and transmission electron microscopy (TEM) studies revealed large anionic complexes that were prone to aggregation and limited cell uptake for RNAi activity. Taken together, these data support the notion that the development of efficient peptide-based siRNA delivery systems is in part contingent on the formulation of discrete nanoparticles that can effectively condense and release siRNA in cells.

Solid phase synthesis and self-assembly of higher-order siRNAs and their bioconjugates

New methods for the synthesis of higher-order siRNA motifs and their bioconjugates have recently gained widespread attention in the development of new and improved gene therapeutics. Our efforts aim to produce new chemical tools and protocols for the generation of modified siRNAs that screen for important oncogene targets as well as silence their activity for effective gene therapy in cancer models. More specifically, we have developed an efficient solution-phase synthesis for the production of a ribouridine branchpoint synthon that can be effectively incorporated by solid phase synthesis within higher-order RNA structures, including those adopting V-, and Y- and >-< shape RNA templates. Self-assembly of complementary RNA to the template strands produced higher-order siRNA nanostructures that were characterized by a combination of PAGE, DLS, and TEM techniques. In an effort to extend the repertoire of functionally diverse siRNAs, we have also developed solid phase bioconjugation strategies for incorporating bio-active probes such as fatty acid appendages and fluorescent reporters. Taken together, these methods highlight the ability to generate higher-order siRNAs and their bioconjugates for exploring the influence of modified siRNA structure on anti-cancer activity.

Enhanced Cancer Theranostics with Self-Assembled, Multilabeled siRNAs

The integration of therapy and diagnostics, termed "theranostics", has recently gained widespread utility in the development of new and improved therapeutics that effectively diagnose and treat diseases, such as cancer. In this study, the covalent attachment of multiple fluorescent labels (i.e., fluorescein isothiocyanate (FITC)) to a wide range of siRNAs, including those adopting linear, V- and Y-shape nanostructures, was successfully accomplished by solid-phase bioconjugation for monitoring cell uptake, co-localization, and biological activity in cell culture. The FITC-labeled higher-order V- and Y-shape siRNAs maintained the requisite hybrid stabilities and A-type helical structures for invoking RNAi activity. The FITC-siRNA hybrids with sense-strand modifiers enabled efficient mRNA knockdown (∼50-90%), which also translated to increased cell death (∼20-95%) in a bone metastatic prostate cancer cell line, over a 72 h incubation period. Significantly, the Y-shaped siRNA containing three FITC probes enhanced fluorescent signaling relative to the siRNA constructs containing single and double fluorophores while retaining potent knockdown and cell death effects post-transfection. Taken together, this data highlights the theranostic utility of the multilabeled FITC-siRNA constructs for potential cancer gene therapy applications.

Direct Transfection of Fatty Acid Conjugated siRNAs and Knockdown of the Glucose-Regulated Chaperones in Prostate Cancer Cells

The emerging field of RNAi nanotechnology has led to rapid advances in the applications of siRNAs in chemical biology, medicinal chemistry, and biotechnology. In our RNAi approach, bioconjugation of linear, V-, and Y-shaped RNA templates were designed using a series of saturated and unsaturated fatty acids to improve cell uptake and knockdown efficacy of the oncogenic glucose regulated proteins (GRPs) in prostate (PC-3) cancer cells. An optimized HCTU-coupling procedure was developed for tagging variable saturated and unsaturated fatty acids onto the 5'-ends of linear and V-shaped RNA templates that were constructed by semiautomated solid phase RNA synthesis. Hybridization and self-assembly of complementary strands yielded linear, V-, and Y-shaped fatty acid-conjugated siRNAs which were characterized by native PAGE. CD spectroscopy confirmed their A-type helix conformations. RP IP HPLC provided trends in amphiphilic properties, whereas DLS and TEM confirmed multicomponent self-assembled structures that were prone to aggregation. Subsequently, the fatty acid conjugated siRNA bioconjugates were tested for their RNAi activity by direct transfection within PC-3 cells known to overexpress oncogenic GRP activity. The siRNA bioconjugates with sense strand modifiers provided more potent GRP knockdown relative to the antisense modified siRNAs, but to a lesser extent when compared to the unconjugated siRNA controls that were transfected with the commercial Trans-IT X2 dynamic delivery system. Flow cytometry revealed that the latter may be at least in part attributed to limited cell uptake of the fatty acid conjugated siRNAs. Nonetheless, these new constructs represent an entry point in modifying higher-order siRNA constructs that may lead to the generation of more efficient siRNA bioconjugates for screening important oncogene targets and for cancer gene therapy applications.

Self-assembled nanomaterials for synergistic antitumour therapy

Recent progress on self-assembled nanodrugs for anticancer treatment was discussed.

Synthesis of native-like crosslinked duplex RNA and study of its properties

A variety of enzymes have been found to interact with double-stranded RNA (dsRNA) in order to carry out its functions. We have endeavored to prepare the covalently crosslinked native-like duplex RNA, which could be useful for biochemical studies and RNA nanotechnology. In this study, the interstrand covalently linked duplex RNA was formed by a crosslinking reaction between vinylpurine (VP) and the target cytosine or uracil in RNA. We measured melting temperatures and CD spectra to identify the properties of the VP crosslinked duplex RNA. The crosslinking formation increased the thermodynamic stability without disturbing the natural conformation of dsRNA. In addition, a competitive binding experiment with the duplex RNA binding enzyme, ADAR2, showed the crosslinked dsRNA bound the protein with nearly the same binding affinity as the natural dsRNA, confirming that it has finely preserved the natural traits of duplex RNA.

Effects of Prolonged GRP78 Haploinsufficiency on Organ Homeostasis, Behavior, Cancer and Chemotoxic Resistance in Aged Mice

GRP78, a multifunctional protein with potent cytoprotective properties, is an emerging therapeutic target to combat cancer development, progression and drug resistance. The biological consequences of prolonged reduction in expression of this essential chaperone which so far has been studied primarily in young mice, was investigated in older mice, as older individuals are likely to be important recipients of anti-GRP78 therapy. We followed cohorts of Grp78+/+ and Grp78+/- male and female mice up to 2 years of age in three different genetic backgrounds and characterized them with respect to body weight, organ integrity, behavioral and memory performance, cancer, inflammation and chemotoxic response. Our results reveal that body weight, organ development and integrity were not impaired in aged Grp78+/- mice. No significant effect on cancer incidence and inflammation was observed in aging mice. Interestingly, our studies detected some subtle differential trends between the WT and Grp78+/- mice in some test parameters dependent on gender and genetic background. Our studies provide the first evidence that GRP78 haploinsufficiency for up to 2 years of age has no major deleterious effect in rodents of different genetic background, supporting the merit of anti-GRP78 drugs in treatment of cancer and other diseases affecting the elderly.