siRNA Packaged with Neutral Cytidinyl/Cationic/PEG Lipids for Enhanced Antitumor Efficiency and Safety In Vitro and In Vivo

Bis-2'-F-cGSASMP isomers encapsulated in cytidinyl/cationic lipids act as potent in situ autologous tumor vaccines

Cancer immunotherapy has greatly improved the prognosis of tumor-bearing patients. Nevertheless, cancer patients exhibit low response rates to current immunotherapy drugs, such as PD1 and PDL1 antibodies. Cyclic dinucleotide analogs are a promising class of immunotherapeutic agents. In this study, in situ autologous tumor vaccines, composed of bis-2'-F-cGSASMP phosphonothioate isomers (FGA-di-pS-2 or FGA-di-pS-4) and cytidinyl/cationic lipids (Mix), were constructed. Intravenous and intratumoral injection of FGA-di-pS-2/Mix or FGA-di-pS-4/Mix enhanced the immunogenic cell death of tumor cells in vivo, leading to the exposure and presentation of whole tumor antigens, inhibiting tumor growth in both LLC and EO771 tumor in situ murine models and increasing their survival rates to 50% and 23%, respectively. Furthermore, the tumor-bearing mice after treatment showed potent immune memory efficacy and exhibited 100% protection against tumor rechallenge. Intravenous administration of FGA-di-pS-2/Mix potently promoted DC maturation, M1 macrophage polarization and CD8+ T cell activation and decreased the proportion of Treg cells in the tumor microenvironment. Notably, two doses of ICD-debris (generated by FGA-di-pS-2 or 4/Mix-treated LLC cells) protected 100% of mice from tumor growth. These tumor vaccines showed promising results and may serve as personalized cancer vaccinations in the future.

Design and synthesis of nucleotidyl lipids and their application in the targeted delivery of siG12D for pancreatic cancer therapy

Nucleic acid drugs are attracting significant attention as prospective therapeutics. However, their efficacy is hindered by challenges in penetrating cell membranes and reaching target tissues, limiting their applications. Nucleotidyl lipids, with their specific intermolecular interactions such as H-bonding and π-π stacking, offer a promising solution as gene delivery vehicles. In this study, a novel series of nucleotide-based amphiphiles were synthesized. These lipid molecules possess the ability to self-assemble into spherical vesicles of appropriate size and zeta potential in aqueous solution. Furthermore, their complexes with oligonucleotides demonstrated favorable biocompatibility and exhibited antiproliferative effects against a broad range of cancer cells. Additionally, when combined with the cationic lipid CLD, these complexes displayed promising in vitro performance and in vivo efficacy. By incorporating DSPE-PEGylated cRGD into the formulation, targeted accumulation of siG12D in pancreatic cancer cells increased from approximately 6% to 18%, leading to effective treatment outcomes (intravenous administration, 1 mg/kg). This finding holds significant importance for the liposomal delivery of nucleic acid drugs to extrahepatic tissues.

Modified ASO conjugates encapsulated with cytidinyl/cationic lipids exhibit more potent and longer-lasting anti-HCC effects

Antisense oligonucleotides (ASOs) are a class of therapeutics targeting mRNAs or genes that have attracted much attention. However, effective delivery and optimal accumulation in target tissues in vivo are still challenging issues. CT102 is an ASO that targets IGF1R mRNA and induces cell apoptosis. Herein, a detailed exploration of the tissue distribution of ASOs delivered by liposomes was carried out. A formulation that resulted in increased hepatic accumulation was identified based on multiple intermolecular interactions between DCP (cytidinyl/cationic lipid DNCA/CLD and DSPE-PEG) and oligonucleotides, including hydrogen bonding, π-π stacking, and electrostatic interactions. The structurally optimized CT102s present a novel strategy for the treatment of hepatocellular carcinoma. The gapmer CT102_MOE5 and conjugate Glu-CT102_MOE5 showed superior antiproliferation and IGF1R mRNA suppression effects at 100 nM in vitro and achieved greater efficacy at a lower dose and administration frequency in vivo. Combined transcriptome and proteome analyses revealed that additional associated targets and functional regulations might simultaneously exist in ASO therapy. These results showed that a combination of lipid encapsulation and structural optimization in the delivery of oligonucleotide drugs has favorable prospects for clinical application.

The intracellular fate and transport mechanism of shape, size and rigidity varied nanocarriers for understanding their oral delivery efficiency

Nanocarriers have become an effective strategy to overcome epithelial absorption barriers. During the absorption process, the endocytosis mechanisms, cell internalization pathways, and transport efficiency of nanocarriers are greatly impacted by their physical properties. To understand the relationship between physical properties of nanocarriers and their abilities overcoming multiple absorption barriers, nanocarriers with variable physical properties were prepared via self-assembly of hydrolyzed α-lactalbumin peptide fragments. The impacts of size, shape, and rigidity of nanocarriers on epithelial cells endocytosis mechanisms, internalization pathways, transport efficiency, and bioavailability were studied systematically. The results showed that nanospheres were mainly internalized via clathrin-mediated endocytosis, which was then locked in lysosomes and degraded enzymatically in cytoplasm. While macropinocytosis was the primary pathway of nanotubes and transported to the endoplasmic reticulum and Golgi apparatus, resulting in a high drug concentration and sustained release in cytoplasm. Besides, nanotubes can overcome the multi-drug resistance by inhibiting the P-glycoprotein efflux. Furthermore, nanotubes can open intercellular tight-junctions instantaneously and reversibly, which promotes transport into blood circulation. The aqueous solubility of hydrophobic bioactive mangiferin (Mgf) was improved by nanocarriers. Most importantly, the bioavailability of Mgf was the highest for cross-linked short nanotube (CSNT) which outperformed free Mgf and other formulations by in vivo pharmacokinetic studies. Finally, Mgf-loaded CSNT showed an excellent therapeutic efficiency in vivo for the intervention of streptozotocin-induced diabetes. These results indicate that cross-linked α-lactalbumin nanotubes could be an effective nanocarrier delivery system for improving the epithelium cellular absorption and bioavailability of hydrophobic bioactive compounds.

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.

Photothermally Responsive siRNA Delivery by PEGylated Poly(amido amine)s for Improved Tumor Therapy

Polycations have a high siRNA binding efficiency, however, their cytotoxicity and poor transfection efficiency prevent their use in siRNA delivery. This study combined PEGylation for enhanced safety with a photothermally controlled endolysosomal escape to improve the cytoplasmic delivery of polycations.We first synthesized PEGylated cationic polymers (denoted as PEG-PHD), which were then used to prepare polyplexes with siRNA and ICG through electrostatic interactions. We found that the cytotoxicity of PEG-PHD and its polyplexes were significantly decreased compared with unPEGylated PHD. The prepared polyplexes successfully induced endolysosomal escape under laser irradiation, thereby showing better siRNA delivery efficiency in vitro and in vivo. Finally, polyplexes carrying siBcl-2 achieved significant inhibition of 4T1 tumor mediated by specific gene silencing after intravenous injection. In conclusion, this biocompatible photothermal controlled delivery platform is suitable for improving the efficiency of siRNA transfection. Overall, this study suggests that combing PEGylation and photoresponsive delivery is a promising strategy for designing siRNA delivery carriers.

Optimization in Chemical Modification of Single-Stranded siRNA Encapsulated by Neutral Cytidinyl/Cationic Lipids

Single-stranded siRNA (ss-siRNA) refers to the antisense strand of siRNA, which plays the role of gene silencing. Since single-stranded RNA is unstable, the present study employed a homemade neutral cytidinyl/cationic lipid delivery system and chemical modifications to improve its stability. The results showed that with the aid of mixed lipids, ss-siRNA could knock down 40% of target mRNA at 25 nM. With 2ʹ-F/2ʹ-OMe, phosphorothioate and 5ʹ-terminal phosphorylation, the optimized ss-siRNA could knock down 80% of target mRNA at 25 nM. Further knocking down AGO2, the ss-siRNAs could not effectively silence target mRNAs. Analysis of the biodistribution in vivo showed that ss-siRNA was less durable than siRNA, but spread more quickly to tissues. This study provides a safe and efficient ss-siRNA delivery and modification strategy, which lays the foundation for future works.

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.