Single and Combinational siRNA Therapy of Cancer Cells: Probing Changes in Targeted and Nontargeted Mediators after siRNA Treatment

Current Advancements in Self-assembling Nanocarriers-Based siRNA Delivery for Cancer Therapy

Different therapeutic practices for treating cancers have significantly evolved to compensate and/or overcome the failures in conventional methodologies. The demonstrated potentiality in completely inhibiting the tumors and in preventing cancer relapse has made nucleic acids therapy (NAT)/gene therapy as an attractive practice. This has been made possible because NAT-based cancer treatments are highly focused on the fundamental mechanisms - i.e., silencing the expression of oncogenic genes responsible for producing abnormal proteins (via messenger RNAs (mRNAs)). However, the future clinical translation of NAT is majorly dependent upon the effective delivery of the exogenous nucleic acids (especially RNAs - e.g., short interfering RNAs (siRNAs) - herein called biological drugs). Moreover, nano-based vehicles (i.e., nanocarriers) are involved in delivering them to prevent degradation and undesired bioaccumulation while enhancing the stability of siRNAs. Herein, we have initially discussed about three major types of self-assembling nanocarriers (liposomes, polymeric nanoparticles and exosomes). Later, we have majorly reviewed recent developments in non-targeted/targeted nanocarriers for delivery of biological drugs (individual/dual) to silence the most important genes/mRNAs accountable for inducing protein abnormality. These proteins include polo-like kinase 1 (PLK1), survivin, vascular endothelial growth factor (VEGF), B-cell lymphoma/leukaemia-2 (Bcl-2) and multi-drug resistance (MDR). Besides, the consequent therapeutic effects on cancer growth, invasion and/or metastasis have also been discussed. Finally, we have comprehensively reviewed the improvements achieved in the cutting-edge cancer therapeutics while delivering siRNAs in combination with clinically approved chemotherapeutic drugs.

Pulmonary surfactant as a versatile biomaterial to fight COVID-19

The COVID-19 pandemic has wielded an enormous pressure on global health care systems, economics and politics. Ongoing vaccination campaigns effectively attenuate viral spreading, leading to a reduction of infected individuals, hospitalizations and mortality. Nevertheless, the development of safe and effective vaccines as well as their global deployment is time-consuming and challenging. In addition, such preventive measures have no effect on already infected individuals and can show reduced efficacy against SARS-CoV-2 variants that escape vaccine-induced host immune responses. Therefore, it is crucial to continue the development of specific COVID-19 targeting therapeutics, including small molecular drugs, antibodies and nucleic acids. However, despite clear advantages of local drug delivery to the lung, inhalation therapy of such antivirals remains difficult. This review aims to highlight the potential of pulmonary surfactant (PS) in the treatment of COVID-19. Since SARS-CoV-2 infection can progress to COVID-19-related acute respiratory distress syndrome (CARDS), which is associated with PS deficiency and inflammation, replacement therapy with exogenous surfactant can be considered to counter lung dysfunction. In addition, due to its surface-active properties and membrane-interacting potential, PS can be repurposed to enhance drug spreading along the respiratory epithelium and to promote intracellular drug delivery. By merging these beneficial features, PS can be regarded as a versatile biomaterial to combat respiratory infections, in particular COVID-19.

R, Bousoik E, Hall R, Barbarino A, Thapa B, Coyle M, Mahdipoor P, Uludağ H. A systematic comparison of lipopolymers for siRNA delivery to multiple breast cancer cell lines: In vitro studies

Small interfering RNA (siRNA) therapy is a promising approach for treatment of a wide range of cancers, including breast cancers that display variable phenotypic features. To explore the general utility of siRNA therapy to control aberrant expression of genes in breast cancer, we conducted a detailed analysis of siRNA delivery and silencing response in vitro in 6 separate breast cancer cell models (MDA-MB-231, MDA-MB-231-KRas-CRM, MCF-7, AU565, MDA-MB-435 and MDA-MB-468 cells). Using lipopolymers for siRNA complexation and delivery, we found a large variation in siRNA delivery efficiency depending on the specific lipopolymer used for siRNA complexation and delivery. Some lipopolymers were effective in all cell types used in this study, indicating the possibility of universal carriers for siRNA therapy. The delivery efficiency for effective lipopolymers was not correlated with dextran uptake in the cells tested, which indicated a receptor-mediated internalization for siRNA complexes with lipopolymers, unlike fluid-phase transfer associated with dextran uptake. Consistent with this, specific inhibitors involved in clathrin- and caveolin-mediated endocytosis significantly (>50%) reduced the internalization of siRNA complexes in all cell types. Using JAK2 and STAT3 silencing in MDA-MB-231 and MDA-MB-468 cells, a general correlation between the uptake and silencing efficiency at the mRNA level was evident, but it appeared that the choice of the target rather than the cell type was more critical for consistent silencing. We conclude that siRNA therapy with lipopolymers can be undertaken in multiple breast cancer cell phenotypes with similar efficiency, indicating the general applicability of non-viral RNAi in clinical management of molecularly heterogeneous breast cancers. STATEMENT OF SIGNIFICANCE: The manuscript investigated the efficacy of siRNA carriers across multiple breast cancer cell lines. The lipopolymeric carriers were capable of delivering effective dose of siRNA to a range of breast cancer cells. Despite some differences in uptake efficiency among cell types, the mechanism of delivery was similar, with CME and CvME significantly involved in the internalization of polyplexes, while fluid-phase endocytosis was not significant. Specific target silencing was correlated to delivery efficiency, but we did notice the presence of lipopolymers that achieved high silencing with minimal siRNA delivery. Silencing specific targets in different cell types were more uniformly achieved as compared to targeting different targets in the same cells. Our studies enhance the feasibility of delivering siRNA to different types of breast cancer cells.

The role of environmental exposures and the epigenome in health and disease

The genetic material of every organism exists within the context of regulatory networks that govern gene expression, collectively called the epigenome. Epigenetics has taken center stage in the study of diseases such as cancer and diabetes, but its integration into the field of environmental health is still emerging. As the Environmental Mutagenesis and Genomics Society (EMGS) celebrates its 50th Anniversary this year, we have come together to review and summarize the seminal advances in the field of environmental epigenomics. Specifically, we focus on the role epigenetics may play in multigenerational and transgenerational transmission of environmentally induced health effects. We also summarize state of the art techniques for evaluating the epigenome, environmental epigenetic analysis, and the emerging field of epigenome editing. Finally, we evaluate transposon epigenetics as they relate to environmental exposures and explore the role of noncoding RNA as biomarkers of environmental exposures. Although the field has advanced over the past several decades, including being recognized by EMGS with its own Special Interest Group, recently renamed Epigenomics, we are excited about the opportunities for environmental epigenetic science in the next 50 years. Environ. Mol. Mutagen. 61:176-192, 2020. © 2019 Wiley Periodicals, Inc.

Heterogeneity and Plasticity of Human Breast Cancer Cells in Response to Molecularly-Targeted Drugs

Non-responsive subpopulation of tumor cells, and acquired resistance in initially responsive cells are major challenges for cancer therapy with molecularly-targeted drugs. While point mutations are considered the major contributing factor to acquired resistance, in this study we explored the role of heterogeneity and plasticity of selected human breast cancer cell lines (MDA-MB-231, MDA-MB-468, and AU565) in their initial and adjusted response, respectively, to ruxolitinib, everolimus, and erlotinib. After determination of lethal concentration for 50% cell death (LC50), cells were exposed to selected drugs using three different approaches: single exposure to 4 × LC50 and collection of surviving cells, multiple exposures to 1.5 × LC50 and monitoring the surviving population, and exposure to gradually increasing concentrations of selected drugs (range of concentrations equivalent to 10% of LC50 to 1.5 × LC50). Surviving cells were studied for adjustments in expression level of selected proteins using quantitative PCR and Western Blot. Our data indicated overexpression of a variety of proteins in resistant populations, which included cell membrane receptors EGFR and HER2, anti-apoptotic proteins Bcl-2 and BIRC8, and other proteins involved in cell signaling (e.g., Akt1, MAPK7, and RPS6KA5). Silencing the identified alternative proteins via siRNA resulted in significant drop in the LC50 of the selected molecularly-targeted drugs cells resistant to ruxolitinib (via targeting Akt), everolimus (via targeting EGFR, MAPK7, RPS6KA5, and HER2), and erlotinib (via silencing Bcl2 and BIRC8). Our data indicates that targeting well-selected alternative proteins could potentially sensitize the resistant cells to the effect of the molecularly-targeted treatment.

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.

Difatty Acyl-Conjugated Linear and Cyclic Peptides for siRNA Delivery

A number of amphiphilic difatty acyl linear and cyclic R5K2 peptide conjugates were synthesized by solid-phase peptide methods to enhance the interaction with the hydrophobic cellular phospholipid bilayer and to improve siRNA delivery and silencing. Binding to siRNA molecules was significantly less for the cyclic peptide conjugates. A gradual decrease was observed in the particle size of the complexes with increasing peptide/siRNA ratio for most of the synthesized peptides, suggesting the complex formation. Most of the complexes showed a particle size of less than 200 nm, which is considered an appropriate size for in vitro siRNA delivery. A number of fatty acyl-conjugated peptides, such as LP-C16 and LP-C18, displayed near complete protection against serum degradation. Flow cytometry studies demonstrated significantly higher internalization of fluorescence-labeled siRNA (FAM-siRNA) in the presence of LP-C16, LP-C18, and CP-C16 with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) addition. Confocal microscopy confirmed the cellular internalization of fluorescence-labeled siRNA in the presence of LP-C16 and LP-C18 with DOPE when compared with cells exposed to DOPE/FAM-siRNA. While C16- and C18-conjugated peptides (especially linear peptides) showed silencing against kinesin spindle protein (KSP) and janus kinase 2 (JAK2) proteins, the addition of DOPE enhanced the silencing efficiency significantly for all selected peptides, except for CP-C16. In conclusion, C16 and C18 difatty acyl peptide conjugates were found to enhance siRNA delivery and generate silencing of targeted proteins in the presence of DOPE. This study provides insights for the design and potential application of optimized difatty acyl peptide/lipid nanoparticles for effective siRNA delivery.

Therapeutic potentials of short interfering RNAs

Short interfering RNA (siRNA) is one of the members of the family of RNA interference (RNAi). Coupled with the RNA-induced silencing complex (RISC), siRNA is able to trigger the cleavage of target RNAs which serve as a defensive system against pathogens. Meanwhile, siRNA in gene silencing opens a new avenue for the treatment of various diseases. SiRNA can effectively inhibit viral infection and replication and suppress tumorigenesis and various inflammation-associated diseases and cardiovascular diseases by inactivation of viral genes and downregulation of oncogene expression. Recently, endogenous siRNAs (endo-siRNAs) were discovered in the reproductive cells of animals which may be associated with regulation of cell division. Structural modification of siRNA enhances the delivery, specificity and efficacy and bioavailability to the target cells. There are at least five categories of siRNA delivery systems including viral vectors, lipid-based nanoparticles, peptide-based nanoparticles, polymer-based nanoparticles and inorganic small molecules like metal ions, silica and carbon. Sufficient preclinical and clinical studies supported that siRNA may be a potential medicine for targeted therapy of various diseases in the near future.