Antisense therapy for cancer

Targeting pediatric solid tumors in the new era of RNA therapeutics

Despite substantial progress in pediatric cancer treatment, poor prognosis remained for patients with recurrent or metastatic disease, given the limitations of approved targeted treatments and immunotherapies. RNA therapeutics offer significant potential for addressing a broad spectrum of diseases, including cancer. Advances in manufacturing and delivery systems are paving the way for the rapid development of therapeutic RNAs for clinical applications. This review summarizes therapeutic RNA classifications and the mechanisms of action, highlighting their potential in manipulating major cancer-related pathways and biological effects. We also focus on the pre-clinical investigation of RNA molecules with efficient delivery systems for their therapeutic potential targeting pediatric solid tumors.

Study of prognostic splicing factors in cancer using machine learning approaches

Splicing factors (SFs) are the major RNA-binding proteins (RBPs) and key molecules that regulate the splicing of mRNA molecules through binding to mRNAs. The expression of splicing factors is frequently deregulated in different cancer types, causing the generation of oncogenic proteins involved in cancer hallmarks. In this study, we investigated the genes that encode RNA-binding proteins and identified potential splicing factors that contribute to the aberrant splicing applying a random forest classification model. The result suggested 56 splicing factors were related to the prognosis of 13 cancers, two SF complexes in liver hepatocellular carcinoma, and one SF complex in esophageal carcinoma. Further systematic bioinformatics studies on these cancer prognostic splicing factors and their related alternative splicing events revealed the potential regulations in a cancer-specific manner. Our analysis found high ILF2-ILF3 expression correlates with poor prognosis in LIHC through alternative splicing. These findings emphasize the importance of SFs as potential indicators for prognosis or targets for therapeutic interventions. Their roles in cancer exhibit complexity and are contingent upon the specific context in which they operate. This recognition further underscores the need for a comprehensive understanding and exploration of the role of SFs in different types of cancer, paving the way for their potential utilization in prognostic assessments and the development of targeted therapies.

Circ_0007432 promotes non-small cell lung cancer progression and macrophage M2 polarization through SRSF1/KLF12 axis

Circular RNAs (circRNAs) plays critical roles in non-small cell lung cancer (NSCLC) development. Herein, we illustrated the effects of circ_0007432 on malignant features of NSCLC. We found that circ_0007432 played a promoting role in NSCLC progression, lying in accelerating cell viability, migration and invasion of NSCLC cells, promoting M2 macrophage polarization, suppressing cell apoptosis of NSCLC cells, and enhancing tumor growth in vivo. Mechanistically, the interactions among circ_0007432, SRSF1, KLF12, and IL-8 were validated by RNA-binding protein immunoprecipitation (RIP), electrophoretic mobility shift assay (EMSA), RNA pull-down, dual luciferase reporter assay and chromatin immunoprecipitation (ChIP) assays. Circ_0007432 upregulated KLF12 by recruiting SRSF1. KLF12 facilitated IL-8 expression and release by binding to IL-8 promoter. Furthermore, the role of circ_0007432/SRSF1/KLF12/IL-8 axis in malignant phenotypes of tumor cells or macrophage polarization was investigated using rescue experiments. In conclusion, circ_0007432 bound with SRSF1 to stabilize KLF12 and then promote IL-8 release, thus promoting malignant behaviors of NSCLC cells and M2 macrophage polarization.

LncRNA LUESCC promotes esophageal squamous cell carcinoma by targeting the miR-6785-5p/NRSN2 axis

Esophageal squamous cell carcinoma (ESCC) is one of the most prevalent gastrointestinal malignancies with high mortality worldwide. Emerging evidence indicates that long noncoding RNAs (lncRNAs) are involved in human cancers, including ESCC. However, the detailed mechanisms of lncRNAs in the regulation of ESCC progression remain incompletely understood. LUESCC was upregulated in ESCC tissues compared with adjacent normal tissues, which was associated with gender, deep invasion, lymph node metastasis, and poor prognosis of ESCC patients. LUESCC was mainly localized in the cytoplasm of ESCC cells. Knockdown of LUESCC inhibited cell proliferation, colony formation, migration, and invasion in vitro and suppressed tumor growth in vivo. Mechanistic investigation indicated that LUESCC functions as a ceRNA by sponging miR-6785-5p to enhance NRSN2 expression, which is critical for the malignant behaviors of ESCC. Furthermore, ASO targeting LUESCC substantially suppressed ESCC both in vitro and in vivo. Collectively, these data demonstrate that LUESCC may exerts its oncogenic role by sponging miR-6785-5p to promote NRSN2 expression in ESCC, providing a potential diagnostic marker and therapeutic target for ESCC patients.

Enhancing Endosomal Escape and Gene Regulation Activity for Spherical Nucleic Acids

The therapeutic potential of small interfering RNAs (siRNAs) is limited by their poor stability and low cellular uptake. When formulated as spherical nucleic acids (SNAs), siRNAs are resistant to nuclease degradation and enter cells without transfection agents with enhanced activity compared to their linear counterparts; however, the gene silencing activity of SNAs is limited by endosomal entrapment, a problem that impacts many siRNA-based nanoparticle constructs. To increase cytosolic delivery, SNAs are formulated using calcium chloride (CaCl2 ) instead of the conventionally used sodium chloride (NaCl). The divalent calcium (Ca2+ ) ions remain associated with the multivalent SNA and have a higher affinity for SNAs compared to their linear counterparts. Importantly, confocal microscopy studies show a 22% decrease in the accumulation of CaCl2 -salted SNAs within the late endosomes compared to NaCl-salted SNAs, indicating increased cytosolic delivery. Consistent with this finding, CaCl2 -salted SNAs comprised of siRNA and antisense DNA all exhibit enhanced gene silencing activity (up to 20-fold), compared to NaCl-salted SNAs regardless of sequence or cell line (U87-MG and SK-OV-3) studied. Moreover, CaCl2 -salted SNA-based forced intercalation probes show improved cytosolic mRNA detection.

Functional Nucleic Acid-Based Immunomodulation for T Cell-Mediated Cancer Therapy

T cell-mediated immunity plays a pivotal role in cancer immunotherapy. The anticancer actions of T cells are coordinated by a sequence of biological processes, including the capture and presentation of antigens by antigen-presenting cells (APCs), the activation of T cells by APCs, and the subsequent killing of cancer cells by activated T cells. However, cancer cells have various means to evade immune responses. Meanwhile, these vulnerabilities provide potential targets for cancer treatments. Functional nucleic acids (FNAs) make up a class of synthetic nucleic acids with specific biological functions. With their diverse functionality, good biocompatibility, and high programmability, FNAs have attracted widespread interest in cancer immunotherapy. This Review focuses on recent research progress in employing FNAs as molecular tools for T cell-mediated cancer immunotherapy, including corresponding challenges and prospects.

N6-methyladenosine-modified circPLPP4 sustains cisplatin resistance in ovarian cancer cells via PIK3R1 upregulation

BACKGROUND

Cisplatin (CDDP) is the first-line chemotherapeutic strategy to treat patients with ovarian cancer (OC). The development of CDDP resistance remains an unsurmountable obstacle in OC treatment and frequently induces tumor recurrence. Circular RNAs (circRNAs) are noncoding RNAs with important functions in cancer progression. Whether circRNAs function in CDDP resistance of OC is unclear.

METHODS

Platinum-resistant circRNAs were screened via circRNA deep sequencing and examined using in situ hybridization (ISH) in OC. The role of circPLPP4 in CDDP resistance was assessed by clone formation and Annexin V assays in vitro, and by OC patient-derived xenografts and intraperitoneal tumor models in vivo. The mechanism underlying circPLPP4-mediated activation of miR-136/PIK3R1 signaling was examined by luciferase reporter assay, RNA pull-down, RIP, MeRIP and ISH.

RESULTS

circPLPP4 was remarkably upregulated in platinum resistant OC. circPLPP4 overexpression significantly enhanced, whereas circPLPP4 silencing reduced, OC cell chemoresistance. Mechanistically, circPLPP4 acts as a microRNA sponge to sequester miR-136, thus competitively upregulating PIK3R1 expression and conferring CDDP resistance. The increased circPLPP4 level in CDDP-resistant cells was caused by increased RNA stability, mediated by increased N6-methyladenosine (m6A) modification of circPLPP4. In vivo delivery of an antisense oligonucleotide targeting circPLPP4 significantly enhanced CDDP efficacy in a tumor model.

CONCLUSIONS

Our study reveals a plausible mechanism by which the m6A -induced circPLPP4/ miR-136/ PIK3R1 axis mediated CDDP resistance in OC, suggesting that circPLPP4 may serve as a promising therapeutic target against CDDP resistant OC. A circPLPP4-targeted drug in combination with CDDP might represent a rational regimen in OC.

Oncofetal reprogramming in tumor development and progression: novel insights into cancer therapy

Emerging evidence indicates that cancer cells can mimic characteristics of embryonic development, promoting their development and progression. Cancer cells share features with embryonic development, characterized by robust proliferation and differentiation regulated by signaling pathways such as Wnt, Notch, hedgehog, and Hippo signaling. In certain phase, these cells also mimic embryonic diapause and fertilized egg implantation to evade treatments or immune elimination and promote metastasis. Additionally, the upregulation of ATP-binding cassette (ABC) transporters, including multidrug resistance protein 1 (MDR1), multidrug resistance-associated protein 1 (MRP1), and breast cancer-resistant protein (BCRP), in drug-resistant cancer cells, analogous to their role in placental development, may facilitate chemotherapy efflux, further resulting in treatment resistance. In this review, we concentrate on the underlying mechanisms that contribute to tumor development and progression from the perspective of embryonic development, encompassing the dysregulation of developmental signaling pathways, the emergence of dormant cancer cells, immune microenvironment remodeling, and the hyperactivation of ABC transporters. Furthermore, we synthesize and emphasize the connections between cancer hallmarks and embryonic development, offering novel insights for the development of innovative cancer treatment strategies.

miRNA-Based Technologies in Cancer Therapy

The discovery of therapeutic miRNAs is one of the most exciting challenges for pharmaceutical companies. Since the first miRNA was discovered in 1993, our knowledge of miRNA biology has grown considerably. Many studies have demonstrated that miRNA expression is dysregulated in many diseases, making them appealing tools for novel therapeutic approaches. This review aims to discuss miRNA biogenesis and function, as well as highlight strategies for delivering miRNA agents, presenting viral, non-viral, and exosomic delivery as therapeutic approaches for different cancer types. We also consider the therapeutic role of microRNA-mediated drug repurposing in cancer therapy.

Oligo-Not Only for Silencing: Overlooked Potential for Multidirectional Action in Plants

Oligo technology is a low-cost and easy-to-implement method for direct manipulation of gene activity. The major advantage of this method is that gene expression can be changed without requiring stable transformation. Oligo technology is mainly used for animal cells. However, the use of oligos in plants seems to be even easier. The oligo effect could be similar to that induced by endogenous miRNAs. In general, the action of exogenously introduced nucleic acids (Oligo) can be divided into a direct interaction with nucleic acids (genomic DNA, hnRNA, transcript) and an indirect interaction via the induction of processes regulating gene expression (at the transcriptional and translational levels) involving regulatory proteins using endogenous cellular mechanisms. Presumed mechanisms of oligonucleotides' action in plant cells (including differences from animal cells) are described in this review. Basic principles of oligo action in plants that allow bidirectional changes in gene activity and even those that lead to heritable epigenetic changes in gene expression are presented. The effect of oligos is related to the target sequence at which they are directed. This paper also compares different delivery methods and provides a quick guide to using IT tools to help design oligonucleotides.

Intra- and Intermolecular Cooperativity in the Catalytic Activity of Phosphodiester Cleavage by Self-Assembled Systems Based on Guanidinylated Calix[4]arenes

The calix[4]arene scaffold, blocked in the cone conformation through alkylation with long alkyl chains, and decorated at the upper rim with four guanidine or arginine units, effectively catalyzes the cleavage of the phosphodiester bond of DNA and RNA model compounds in water. An exhaustive kinetic investigation unequivocally points to the existence of spontaneous aggregation phenomena, driven by hydrophobic effect, occurring at different critical concentrations that depend on the identity of the compound. A pronounced superiority of the assembled structures compared with the monomers in solution was observed. Moreover, the catalytically active units, clustered on the macrocyclic tetrafunctional scaffold, were proved to efficiently cooperate in the catalytic mechanism and result in improved reaction rates compared to those of the monofunctional model compounds. The kinetic analysis is also integrated and corroborated with further experiments based on fluorescence spectroscopy and light scattering. The advantage of the supramolecular assemblies based on tetrafunctional calixarenes leads to believe that the active units can cooperate not only intramolecularly but also intermolecularly. The molecules in the aggregates can probably mold, flex and rearrange but, at the same time, keep an ordered structure that favors phosphodiester bond cleavage. This dynamic preorganization can allow the catalytic units to reach a better fitting with the substrates and perform a superior catalytic activity.

Cancer-cell-membrane-camouflaged supramolecular self-assembly of antisense oligonucleotide and chemodrug for targeted combination therapy

The anti-apoptotic B-cell lymphoma-2 (Bcl-2) family of proteins are critical regulators of cell death that are overexpressed in many cancer cells, especially in multi-drug resistant cancer cells. Combinatorial gene- and chemotherapies using antisense oligonucleotides (ASOs) to suppress the expression of Bcl-2-family mRNA and restore the sensitivity of the cell to chemodrugs provide a promising pathway for anticancer treatment. However, intrinsic differences between macromolecular ASOs and small molecular chemodrugs make their co-delivery challenging. Moreover, extraneous carriers may induce immunogenicity and inflammation problems. Herein, we develop a targeted nanodrug delivery system using the cationic amphiphilic chemodrug mitoxantrone (Mito), which interacts with Bcl-2 ASO through electrostatic interaction and self-assembles into nanoparticles (NP_[Bcl-2/Mito]), whose size can be controlled by regulating the ratio of ASO and Mito. NP_[Bcl-2/Mito] can protect the ASO from degradation during delivery and combine gene- and chemotherapies to improve the anticancer effect. Furthermore, cancer cell membranes (CCMs) derived from homologous tumors were used to camouflage NP_[Bcl-2/Mito] (NP_[Bcl-2/Mito]@CCM) to achieve immune escape and tumor targeting. Both in vitro and in vivo assessments demonstrate the excellent performance of NP_[Bcl-2/Mito]@CCM for drug-resistant breast tumor therapy. This CCM-camouflaged ASO/chemodrug nanoplatform provides a promising pathway for the targeted delivery of ASOs and chemodrugs for tumor combination therapy.

Near-Quantitative Preparation of Short Single-Stranded DNA Circles

Small, single-stranded DNA (ssDNA) circles have many applications, such as templating rolling circle amplification (RCA), capturing microRNAs, and scaffolding DNA nanostructures. However, it is challenging to prepare such ssDNA circles, particularly when the DNA size becomes very small (e.g. a 20 nucleotide (nt) long ssDNA circle). Often, such short ssDNA dominantly form concatemers (either linear or circular) due to intermolecular ligation, instead of forming monomeric ssDNA circles by intramolecular ligation. Herein, a simple method to overcome this problem by designing the complementary linker molecules is reported. It is demonstrated that ssDNA, as short as 16 nts, can be enzymatically ligated (by the commonly used T4 DNA ligase) into monomeric ssDNA circles at high concentration (100 μM) with high yield (97 %). This method does not require any special sequence, thus, it is expected to be generally applicable. The experimental protocol is identical to regular DNA ligation, thus, is expected to be user friendly for general chemists and biologists.

Preparation and characterization of a gemini surfactant-based biomimetic complex for gene delivery

Gemini surfactants (GS) have been explored as non-viral gene delivery systems. Nevertheless, their cytotoxicity and the limitations in the in vivo studies have impeded their development. To attenuate toxicity and further explore their possibilities in gene delivery, a series of GS (18-7-18)-based gene delivery systems complexed with red blood cell membranes (RBCM) or/and DOPE-PEG₂₀₀₀ (DP) were prepared and evaluated. EGFP-encoding plasmids were delivered via GS-based complexes and the efficiency of gene transfection was evaluated by imaging of the major organs after intravenous administration in mice and qPCR quantification in hepatocytes. In order to assess the safety of GS-based complexes, the hemolysis test, serum biochemical indices, H&E staining and CCK-8 test were examined. The results revealed that EGFP was primarily expressed in livers, and all complexes showed minimal acute toxicity to major organs. Moreover, we found that the dual incorporation of RBCM and DP could significantly elevate the transfection efficiency and cell viability in hepatocytes. Overall, the results indicated that GS-based complexes possessed great potential as vectors for gene delivery both in vivo and in vitro and the dual incorporation of RBCM and DP could be a promising gene delivery approach with high transfection efficacy and low toxicity.

Antisense oligonucleotide is a promising intervention for liver diseases

As the body's critical metabolic organ, the liver plays an essential role in maintaining proper body homeostasis. However, as people's living standards have improved and the number of unhealthy lifestyles has increased, the liver has become overburdened. These have made liver disease one of the leading causes of death worldwide. Under the influence of adverse factors, liver disease progresses from simple steatosis to hepatitis, to liver fibrosis, and finally to cirrhosis and cancer, followed by increased mortality. Until now, there has been a lack of accepted effective treatments for liver disease. Based on current research, antisense oligonucleotide (ASO), as an alternative intervention for liver diseases, is expected to be an effective treatment due to its high efficiency, low toxicity, low dosage, strong specificity, and additional positive characteristics. In this review, we will first introduce the design, modification, delivery, and the mechanisms of ASO, and then summarize the application of ASO in liver disease treatment, including in non-alcoholic fatty liver disease (NAFLD), hepatitis, liver fibrosis, and liver cancer. Finally, we discuss challenges and perspectives on the transfer of ASO drugs into clinical use. This review provides a current and comprehensive understanding of the integrative and systematic functions of ASO for its use in liver disease.

Roles of TGF-β in cancer hallmarks and emerging onco-therapeutic design

Transforming growth factor-beta (TGF-β) is a double-edged sword in cancer treatment because of its pivotal yet complex and roles played during cancer initiation/development. Current anti-cancer strategies involving TGF-β largely view TGF-β as an onco-therapeutic target that not only substantially hinders its full utilisation for cancer control, but also considerably restricts innovations in this field. Thereby, how to take advantages of therapeutically favourable properties of TGF-β for cancer management represents an interesting and less investigated problem. Here, by categorising cancer hallmarks into four critical transition events and one enabling characteristic controlling cancer initiation and progression, and delineating TGF-β complexities according to these cancer traits, we identify the suppressive role of TGF-β in tumour initiation and early-stage progression and its promotive functionalities in cancer metastasis as well as other cancer hallmarks. We also propose the feasibility and possible scenarios of combining cold atmospheric plasma (CAP) with onco-therapeutics utilising TGF-β for cancer control given the intrinsic properties of CAP against cancer hallmarks.

Microflow LC-MS/MS to improve sensitivity for antisense oligonucleotides bioanalysis: critical role of sample cleanness

Background: Quantitative bioanalysis of antisense oligonucleotides (ASOs) is crucial to study their pharmacokinetic properties. An ultrasensitive bioanalytical method is often desired for quantifying low-concentration ASOs. Results: Effects of microflow LC and sample cleanness on sensitivity improvement of ASOs were evaluated. Sixfold sensitivity improvement of ASO-001 was achieved using microflow LC-MS/MS compared with conventional analytical flow method. Different sample extracts (hybridization, SPE and protein precipitation) were evaluated for sensitivity improvement by microflow LC. More sensitivity improvement was observed in the cleaner sample extract. Conclusion: Microflow LC increases sensitivity for ASO bioanalysis. The cleaner the sample extract, the better the sensitivity improvement. An ultrasensitive hybridization microflow LC-MS/MS method with lower limit of quantification of 0.100 ng/ml was developed and qualified for quantifying ASO-001 in plasma.

Beyond Triphosphates: Reagents and Methods for Chemical Oligophosphorylation

Oligophosphates play essential roles in biochemistry, and considerable research has been directed toward the synthesis of both naturally occurring oligophosphates and their synthetic analogues. Greater attention has been given to mono-, di-, and triphosphates, as these are present in higher concentrations biologically and easier to synthesize. However, extended oligophosphates have potent biochemical roles, ranging from blood coagulation to HIV drug resistance. Sporadic reports have slowly built a niche body of literature related to the synthesis and study of extended oligophosphates, but newfound interests and developments have the potential to rapidly expand this field. Here we report on current methods to synthesize oligophosphates longer than triphosphates and comment on the most important future directions for this area of research. The state of the art has provided fairly robust methods for synthesizing nucleoside 5'-tetra- and pentaphosphates as well as dinucleoside 5',5'-oligophosphates. Future research should endeavor to push such syntheses to longer oligophosphates while developing synthetic methodologies for rarer morphologies such as 3'-nucleoside oligophosphates, polyphosphates, and phosphonate/thiophosphate analogues of these species.

Targeted Osmotic Lysis: A Novel Approach to Targeted Cancer Therapies

The conventional treatment of cancer has been based on the delivery of non-selective toxins and/or ionizing energy that affect both the cancer and normal tissues in the hope of destroying the offending disease before killing the patient. Unfortunately, resistance often develops to these treatments and patients experience severe, dose-limiting adverse effects that reduce treatment efficacy and compromise quality of life. Recent advances in our knowledge of the biology of tumor cells and their microenvironment, the recognition of surface proteins that are unique to specific cancers and essential to cell growth and survival and signaling pathways associate with invasion and metastasis have led to the development of targeted therapies that are able to identify specific cellular markers and more selectively deliver lethal treatment to the invading cancer thus improving efficacy and limiting adverse effects. In the context of targeted approaches to cancer therapy, we present targeted osmotic lysis as a novel and fundamentally different approach for treating advanced-stage carcinoma that exploits the conserved relationship between voltage-gated sodium channels and Na⁺, K⁺-ATPase and has the potential to increase survival without compromising quality of life in a broad spectrum of highly malignant forms of cancer.

MicroRNA as a Potential Therapeutic Molecule in Cancer

Small noncoding RNAs, as post-translational regulators of many target genes, are not only markers of neoplastic disease initiation and progression, but also markers of response to anticancer therapy. Hundreds of miRNAs have been identified as biomarkers of drug resistance, and many have demonstrated the potential to sensitize cancer cells to therapy. Their properties of modulating the response of cells to therapy have made them a promising target for overcoming drug resistance. Several methods have been developed for the delivery of miRNAs to cancer cells, including introducing synthetic miRNA mimics, DNA plasmids containing miRNAs, and small molecules that epigenetically alter endogenous miRNA expression. The results of studies in animal models and preclinical studies for solid cancers and hematological malignancies have confirmed the effectiveness of treatment protocols using microRNA. Nevertheless, the use of miRNAs in anticancer therapy is not without limitations, including the development of a stable nanoconstruct, delivery method choices, and biodistribution. The aim of this review was to summarize the role of miRNAs in cancer treatment and to present new therapeutic concepts for these molecules. Supporting anticancer therapy with microRNA molecules has been verified in numerous clinical trials, which shows great potential in the treatment of cancer.

Long non-coding RNA LINC00680 functions as a ceRNA to promote esophageal squamous cell carcinoma progression through the miR-423-5p/PAK6 axis

Background

Esophageal squamous cell carcinoma (ESCC) is a common invasive malignancy worldwide with poor clinical outcomes. Increasing amount of long non-coding RNAs (lncRNAs) have been reported to be involved in cancer development. However, lncRNAs that are functional in ESCC and the underlying molecular mechanisms remain largely unknown.

Methods

Transcriptomic analysis was performed to identify dysregulated lncRNAs in ESCC tissue samples. The high expression of LINC00680 in ESCC was validated by RT-qPCR, and the oncogenic functions of LINC00680 was investigated by cell proliferation, colony formation, migration and invasion assays in ESCC cells in vitro and xenografts derived from ESCC cells in mice. RNA-seq, competitive endogenous RNA (ceRNA) network analysis, and luciferase reporter assays were carried out to identify LINC00680 target genes and the microRNAs (miRNAs) bound to LINC00680. Antisense oligonucleotides (ASOs) were used for in vivo treatment.

Results

Transcriptome profiling revealed that a large number of lncRNAs was dysregulated in ESCC tissues. Notably, LINC00680 was highly expressed, and upregulation of LINC00680 was associated with large tumor size, advanced tumor stage, and poor prognosis. Functionally, knockdown of LINC00680 restrained ESCC cell proliferation, colony formation, migration, and invasion in vitro and inhibited tumor growth in vivo. Mechanistically, LINC00680 was found to act as a ceRNA by sponging miR-423-5p to regulate PAK6 (p21-activated kinase 6) expression in ESCC cells. The cell viability and motility inhibition induced by LINC00680 knockdown was significantly reversed upon PAK6 restoration and miR-423-5p inhibition. Furthermore, ASO targeting LINC00680 substantially suppressed ESCC both in vitro and in vivo.

Conclusions

An oncogenic lncRNA, LINC00680, was identified in ESCC, which functions as a ceRNA by sponging miR-423-5p to promote PAK6 expression and ESCC. LINC00680/miR-423-5p/PAK6 axis may serve as promising diagnostic and prognostic biomarkers and therapeutic targets for ESCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01539-3.

Supramolecular grafting of stimuli-responsive, carrier-free, self-deliverable nanoparticles of camptothecin and antisense DNA for combination cancer therapy

A supramolecular approach for the crafting of self-deliverable nanoparticles of antisense DNA and camptothecin for combination cancer therapy is reported.

Advances in Therapeutic L-Nucleosides and L-Nucleic Acids with Unusual Handedness

Nucleic-acid-based small molecule and oligonucleotide therapies are attractive topics due to their potential for effective target of disease-related modules and specific control of disease gene expression. As the non-naturally occurring biomolecules, modified DNA/RNA nucleoside and oligonucleotide analogues composed of L-(deoxy)riboses, have been designed and applied as innovative therapeutics with superior plasma stability, weakened cytotoxicity, and inexistent immunogenicity. Although all the chiral centers in the backbone are mirror converted from the natural D-nucleic acids, L-nucleic acids are equipped with the same nucleobases (A, G, C and U or T), which are critical to maintain the programmability and form adaptable tertiary structures for target binding. The types of L-nucleic acid drugs are increasingly varied, from chemically modified nucleoside analogues that interact with pathogenic polymerases to nanoparticles containing hundreds of repeating L-nucleotides that circulate durably in vivo. This article mainly reviews three different aspects of L-nucleic acid therapies, including pharmacological L-nucleosides, Spiegelmers as specific target-binding aptamers, and L-nanostructures as effective drug-delivery devices.

Antisense Oligonucleotide-Mediated Splice Switching: Potential Therapeutic Approach for Cancer Mitigation

Splicing is an essential process wherein precursor messenger RNA (pre-mRNA) is reshaped into mature mRNA. In alternative splicing, exons of any pre-mRNA get rearranged to form mRNA variants and subsequently protein isoforms, which are distinct both by structure and function. On the other hand, aberrant splicing is the cause of many disorders, including cancer. In the past few decades, developments in the understanding of the underlying biological basis for cancer progression and therapeutic resistance have identified many oncogenes as well as carcinogenic splice variants of essential genes. These transcripts are involved in various cellular processes, such as apoptosis, cell signaling and proliferation. Strategies to inhibit these carcinogenic isoforms at the mRNA level are promising. Antisense oligonucleotides (AOs) have been developed to inhibit the production of alternatively spliced carcinogenic isoforms through splice modulation or mRNA degradation. AOs can also be used to induce splice switching, where the expression of an oncogenic protein can be inhibited by the induction of a premature stop codon. In general, AOs are modified chemically to increase their stability and binding affinity. One of the major concerns with AOs is efficient delivery. Strategies for the delivery of AOs are constantly being evolved to facilitate the entry of AOs into cells. In this review, the different chemical modifications employed and delivery strategies applied are discussed. In addition to that various AOs in clinical trials and their efficacy are discussed herein with a focus on six distinct studies that use AO-mediated exon skipping as a therapeutic strategy to combat cancer.

Role of immunotherapy in Ewing sarcoma

Ewing sarcoma (ES) is thought to arise from mesenchymal stem cells and is the second most common bone sarcoma in pediatric patients and young adults. Given the dismal overall outcomes and very intensive therapies used, there is an urgent need to explore and develop alternative treatment modalities including immunotherapies. In this article, we provide an overview of ES biology, features of ES tumor microenvironment (TME) and review various tumor-associated antigens that can be targeted with immune-based approaches including cancer vaccines, monoclonal antibodies, T cell receptor-transduced T cells, and chimeric antigen receptor T cells. We highlight key reasons for the limited efficacy of various immunotherapeutic approaches for the treatment of ES to date. These factors include absence of human leukocyte antigen class I molecules from the tumor tissue, lack of an ideal surface antigen, and immunosuppressive TME due to the presence of myeloid-derived suppressor cells, F2 fibrocytes, and M2-like macrophages. Lastly, we offer insights into strategies for novel therapeutics development in ES. These strategies include the development of gene-modified T cell receptor T cells against cancer–testis antigen such as XAGE-1, surface target discovery through detailed profiling of ES surface proteome, and combinatorial approaches. In summary, we provide state-of-the-art science in ES tumor immunology and immunotherapy, with rationale and recommendations for future therapeutics development.

iRGD-liposomes enhance tumor delivery and therapeutic efficacy of antisense oligonucleotide drugs against primary prostate cancer and bone metastasis

Nucleotide-based drugs, such as antisense oligonucleotides (ASOs), have unique advantages in treating human diseases as they provide virtually unlimited ability to target any gene. However, their clinical translation faces many challenges, one of which is poor delivery to the target tissue in vivo. This problem is particularly evident in solid tumors. Here, we functionalized liposomes with a tumor-homing and -penetrating peptide, iRGD, as a carrier of an ASO against androgen receptor (AR) for prostate cancer treatment. The iRGD-liposomes exhibited a high loading efficiency of AR-ASO, and an efficient knockdown of AR gene products was achieved in vitro, including AR splice variants. In vivo, iRGD-liposomes significantly increased AR-ASO accumulation in the tumor tissue and decreased AR expression relative to free ASOs in prostate tumors established as subcutaneous xenografts. Similar results were obtained with intra-tibial xenografts modeling metastasis to bones, the predominant site of metastasis for prostate cancer. In treatment studies, iRGD-liposomes markedly improved the AR-ASO efficacy in suppressing the growth of both subcutaneous xenografts and intra-tibial xenografts. The inhibitory effect on tumor growth was also significantly prolonged by the delivery of the AR-ASO in the iRGD-liposomes. Meanwhile, iRGD-liposomes did not increase ASO accumulation or toxicity in healthy organs. Overall, we provide here a delivery system that can significantly increase ASO accumulation and efficacy in solid tumors. These benefits are achieved without significant side effects, providing a way to increase the antitumor efficacy of ASOs.

Hydrogel based lipid-oligonucleotides: a new route to self-delivery of therapeutic sequences

Synthetic OligoNucleotides (ON) provide promising therapeutic tools for controlling specifically genetic expression in a broad range of diseases from cancers to viral infections. Beside their chemical stability and intracellular delivery, the controlled release of therapeutic sequences remains an important challenge for successful clinical applications. In this work, Lipid-OligoNucleotide (LON) conjugates stabilizing hydrogels are reported and characterized by rheology and cryo-scanning electron microscopy (cryo-SEM). These studies revealed that lipid conjugation of antisense oligonucleotides featuring partial self-complementarity resulted in entangled pearl-necklace networks, which were obtained through micelle-micelle interaction driven by duplex formation. Owing to these properties, the Lipid AntiSense Oligonucleotide (LASO) sequences exhibited a prolonged release after subcutaneous administration compared to the non-lipidic antisense (ASO) one. The LASO self-assembly based hydrogels obtained without adjuvant represent an innovative approach for the sustained self-delivery of therapeutic oligonucleotides.

Novel therapies emerging in oncology to target the TGF-β pathway

The TGF-β signaling pathway governs key cellular processes under physiologic conditions and is deregulated in many pathologies, including cancer. TGF-β is a multifunctional cytokine that acts in a cell- and context-dependent manner as a tumor promoter or tumor suppressor. As a tumor promoter, the TGF-β pathway enhances cell proliferation, migratory invasion, metastatic spread within the tumor microenvironment and suppresses immunosurveillance. Collectively, the pleiotropic nature of TGF-β signaling contributes to drug resistance, tumor escape and undermines clinical response to therapy. Based upon a wealth of preclinical studies, the TGF-β pathway has been pharmacologically targeted using small molecule inhibitors, TGF-β-directed chimeric monoclonal antibodies, ligand traps, antisense oligonucleotides and vaccines that have been now evaluated in clinical trials. Here, we have assessed the safety and efficacy of TGF-β pathway antagonists from multiple drug classes that have been evaluated in completed and ongoing trials. We highlight Vactosertib, a highly potent small molecule TGF-β type 1 receptor kinase inhibitor that is well-tolerated with an acceptable safety profile that has shown efficacy against multiple types of cancer. The TGF-β ligand traps Bintrafusp alfa (a bifunctional conjugate that binds TGF-β and PD-L1), AVID200 (a computationally designed trap of TGF-β receptor ectodomains fused to an Fc domain) and Luspatercept (a recombinant fusion that links the activin receptor IIb to IgG) offer new ways to fight difficult-to-treat cancers. While TGF-β pathway antagonists are rapidly emerging as highly promising, safe and effective anticancer agents, significant challenges remain. Minimizing the unintentional inhibition of tumor-suppressing activity and inflammatory effects with the desired restraint on tumor-promoting activities has impeded the clinical development of TGF-β pathway antagonists. A better understanding of the mechanistic details of the TGF-β pathway should lead to more effective TGF-β antagonists and uncover biomarkers that better stratify patient selection, improve patient responses and further the clinical development of TGF-β antagonists.

General Method for Post-Synthetic Modification of Oligonucleotides Based on Oxidative Amination of 4-Thio-2'-deoxyuridine

Functionalized oligonucleotides (ONs) are widely applied as target binding molecules for biosensing and regulators for gene expression. Numerous efforts have been focused on developing facile methods for preparing these useful ONs carrying diverse modifications. Herein, we present a general method for postsynthetic modification of ONs via oxidative amination of 4-thio-2'-deoxyuridine (4SdU). 4SdU-containing ON can be derived by both alkyl and aromatic amines. Using this approach, ONs are successfully attached with alkyne/azide, biotin and dansylamide moieties, and these as-prepared ONs possess the expected biorthogonal reactivity, streptavidin affinity and fluorescent property, respectively. Furthermore, we also directly install fluorophores to the ON nucleobase based on oxidative amination of 4SdU, and these fluorophores exhibit distinct luminescence behaviors before and after conjugation. We believe our method will be a versatile strategy for constructing various functionalized ONs used in a wide range of nucleic acid applications.

AlphaB-crystallin and breast cancer: role and possible therapeutic strategies

AlphaB-crystallin (HSPB5) is one of the most prominent and well-studied members of the small heat shock protein (sHsp) family. To date, it is known that this protein modulates significant cellular processes and therefore, it is not surprising that its deregulation is involved in various human pathologies, including cancer diseases. Despite the pathogenic significance of HSPB5 in cancer and its regulatory mechanism related to aggressiveness is poorly understood, several reports describe the association of breast carcinoma progression with HSPB5, whose expression is also considered an independent predictor of breast cancer metastasis to the brain. Indeed, numerous authors indicate HSPB5 as a new valuable biomarker for clinicopathological parameters and poor prognosis in breast cancer. Considering the cytoprotective, anti-apoptotic, pro-angiogenic, and pro-metastatic properties of the sHsps, it is not surprising that they are considered as promising targets for anticancer treatment, even though, at present, a deeper understanding of their mode of action is needed to allow the development of precise therapeutic interventions. Data on the direct inhibition of different sHsps demonstrate promising results in cancer pathologies; however, specific strategies against HSPB5 have not been considered. This review highlights the most relevant findings on HSPB5 and its role in breast cancer, as well as the possible strategies in using HSPB5 inhibition for therapeutic purposes.

Role of Lipid-Based and Polymer-Based Non-Viral Vectors in Nucleic Acid Delivery for Next-Generation Gene Therapy

The field of gene therapy has experienced an insurgence of attention for its widespread ability to regulate gene expression by targeting genomic DNA, messenger RNA, microRNA, and short-interfering RNA for treating malignant and non-malignant disorders. Numerous nucleic acid analogs have been developed to target coding or non-coding sequences of the human genome for gene regulation. However, broader clinical applications of nucleic acid analogs have been limited due to their poor cell or organ-specific delivery. To resolve these issues, non-viral vectors based on nanoparticles, liposomes, and polyplexes have been developed to date. This review is centered on non-viral vectors mainly comprising of cationic lipids and polymers for nucleic acid-based delivery for numerous gene therapy-based applications.

pH-sensitive PEG-coated hyper-branched β-d-glucan derivative as carrier for CpG oligodeoxynucleotide delivery

β-d-glucan is a natural non-digestible polysaccharide that can be selectively recognized by recognition receptors such as Dectin-1 receptors, resulting in an emerging interest on exploring its capacity for carrying biological information to desired organs or cells. CpG oligodeoxynucleotide (ODN) has the potentiality to initiate an immune-stimulatory cascade via activating B cells inducing proinflammatory cytokines, which is conducive to immunotherapy and nucleic acid vaccine. Herein, we developed a pH-sensitive delivery system loading with CpG ODN by introducing poly-ethylenimine (PEI) to a hyperbranched β-d-glucan (HBB) and coating with poly-ethylene glycol (PEG) shell via acidic liable Schiff bond. This delivery system exhibited a favorable biocompatibility and facilitated the cellular uptake of CpG ODN at pH 6.8 with the possibility of having higher accumulation in acidic cancer microenvironment. Furthermore, this carrier together with class B CpG ODN could enhance the secretion of cytokines including interleukin-6 and interferon-α as well as capable of interferon-α induction.

Cytochalasin-B-Inducible Nanovesicle Mimics of Natural Extracellular Vesicles That Are Capable of Nucleic Acid Transfer

Extracellular vesicles provide cell-to-cell communication and have great potential for use as therapeutic carriers. This study was aimed at the development of an extracellular vesicle-based system for nucleic acid delivery. Three types of nanovesicles were assayed as oligonucleotide carriers: mesenchymal stem cell-derived extracellular vesicles and mimics prepared either by cell treatment with cytochalasin B or by vesicle generation from plasma membrane. Nanovesicles were loaded with a DNA oligonucleotide by freezing/thawing, sonication, or permeabilization with saponin. Oligonucleotide delivery was assayed using HEK293 cells. Extracellular vesicles and mimics were characterized by a similar oligonucleotide loading level but different efficiency of oligonucleotide delivery. Cytochalasin-B-inducible nanovesicles exhibited the highest level of oligonucleotide accumulation in HEK293 cells and a loading capacity of 0.44 ± 0.05 pmol/µg. The loaded oligonucleotide was mostly protected from nuclease action.

LINC00673 is activated by YY1 and promotes the proliferation of breast cancer cells via the miR-515-5p/MARK4/Hippo signaling pathway

Background

An increasing number of studies have shown that long noncoding RNAs (lncRNAs) play essential roles in tumor initiation and progression. LncRNAs act as tumor promoters or suppressors by targeting specific genes via epigenetic modifications and competing endogenous RNA (ceRNA) mechanisms. In this study, we explored the function and detailed mechanisms of long intergenic nonprotein coding RNA 673 (LINC00673) in breast cancer progression.

Methods

Quantitative real-time PCR (qRT-PCR) was used to examine the expression of LINC00673 in breast cancer tissues and in adjacent normal tissues. Gain-of-function and loss-of function experiments were conducted to investigate the biological functions of LINC00673 in vitro and in vivo. We also explored the potential role of LINC00673 as a therapeutic target using antisense oligonucleotide (ASO) in vivo. RNA sequencing (RNA-seq), dual-luciferase reporter assays, chromatin immunoprecipitation (ChIP) assay, and rescue experiments were performed to uncover the detailed mechanism of LINC00673 in promoting breast cancer progression.

Results

In the present study, LINC00673 displayed a trend of remarkably increased expression in breast cancer tissues and was associated with poor prognosis in breast cancer patients. Importantly, LINC00673 depletion inhibited breast cancer cell proliferation by inhibiting the cell cycle and increasing apoptosis. Furthermore, ASO therapy targeting LINC00673 substantially suppressed breast cancer cell proliferation in vivo. Mechanistically, LINC00673 was found to act as a ceRNA by sponging miR-515-5p to regulate MARK4 expression, thus inhibiting the Hippo signaling pathway. Finally, ChIP assay showed that the transcription factor Yin Yang 1 (YY1) could bind to the LINC00673 promoter and increase its transcription in cis.

Conclusions

YY1-activated LINC00673 may exert an oncogenic function by acting as a sponge for miR-515-5p to upregulate the MARK4 and then inhibit Hippo signaling pathway, and may serve as a potential therapeutic target.

Development of gapmer antisense oligonucleotide with deoxyribonucleic guanidine (DNG) modifications

The properties of gapmer antisense oligonucleotide (ASO) flanked by deoxyribonucleic guanidine (DNG) were investigated for the potential application in antisense technology. DNG is a unique nucleotide analog which has a positively charged internucleotide guanidinium linkage instead of negatively charged phosphodiester backbone linkage. We prepared a gapmer ASO containing DNG units at both wings of the sequence and compared its properties with 2',4'-BNA/LNA gapmer ASOs with phosphorothioate (PS) backbone. Although DNG gapmer showed no stabilizing effect on the duplex formation with target RNA, the DNG modification was found to be tolerant to exonuclease digestion. Furthermore, DNG gapmer can induce RNase H-mediated cleavage of target RNA molecule, a requisite property for the antisense strategy. Therefore, the DNG gapmer developed in this study could be an interesting and useful candidate for the development of potent ASOs.

Dendrimer-Enabled Therapeutic Antisense Delivery Systems as Innovation in Medicine

Antisense oligonucleotide (AON)-based therapies concern the treatment for genetic disorders or infections such as a range of neurodegenerative and neuromuscular diseases and have shown benefits in animal models and patients. Nevertheless, successes in the clinic are still strongly limited by unfavorable biodistribution and poor cellular uptake of AONs. Dendrimer macromolecules are synthetically accessible and consist of a core with repeated iterations (named branches) surrounding this core, and on the periphery functional groups which can be modified for ligand attachment. The generations of these branched nanoparticles are based on the number of branches emanating from the core with layered architectures. Dendrimers show promise in several biomedical applications based on their tunable surface modifications allowing the adjustment of their in vivo behavior related to biocompatibility and pharmacokinetic parameters. Dendrimers can be used as nanocarriers of various types of drugs including AONs or nanodrugs. As nanocarriers, polycationic dendrimers can complex multiple negatively charged DNA oligonucleotides on their surface and form stable complexes to promote internalization into the cells based on a good cell membrane affinity. These nanocarriers complexing antisense oligonucleotides must be stable enough to reach the cellular target, but with adequate in vivo global clearance, and have good pharmacokinetic (PK) and pharmacodynamic (PD) profiles. This Review was designed to analyze the development of AONs carried by polycationic and polyanionic (few example) dendrimers. This Review strongly supports the idea that dendrimers, with adequate modulation of their terminal groups, could be used to carry AONs in cells.

Exploiting Signaling Pathways and Immune Targets Beyond the Standard of Care for Ewing Sarcoma

Ewing sarcoma (ES) family of tumors includes bone and soft tissue tumors that are often characterized by a specific translocation between chromosome 11 and 22, resulting in the EWS-FLI1 fusion gene. With the advent of multi-modality treatment including cytotoxic chemotherapy, surgery, and radiation therapy, the prognosis for patients with ES has substantially improved. However, a therapeutic plateau is now reached for both localized and metastatic disease over the last two decades. Burdened by the toxicity limits associated with the current frontline systemic therapy, there is an urgent need for novel targeted therapeutic strategies. In this review, we discuss the current treatment paradigm of ES, and explore preclinical evidence and emerging treatments directed at tumor signaling pathways and immune targets.

A Multifunctional Peptide-Conjugated AIEgen for Efficient and Sequential Targeted Gene Delivery into the Nucleus

Gene therapy has immense potential as a therapeutic approach to serious diseases. However, efficient delivery and real-time tracking of gene therapeutic agents have not been solved well for successful gene-based therapeutics. Herein we present a versatile gene-delivery strategy for efficient and visualized delivery of therapeutic genes into the targeted nucleus. We developed an integrin-targeted, cell-permeable, and nucleocytoplasmic trafficking peptide-conjugated AIEgen named T_D NCP for the efficient and sequential targeted delivery of an antisense single-stranded DNA oligonucleotide (ASO) and tracking of the delivery process into the nucleus. As compared with T_D NCP/siRNA-NPs (siRNA functions mainly in the cytoplasm), T_D NCP/ASO-NPs (ASO functions mainly in the nucleus) exhibited a better interference effect, which further indicates that T_D NCP is a nucleus-targeting vector. Moreover, T_D NCP/ASO-NPs showed a favorable tumor-suppressive effect in vivo.

Bag-1 silencing enhanced chemotherapeutic drug-induced apoptosis in MCF-7 breast cancer cells affecting PI3K/Akt/mTOR and MAPK signaling pathways

The multifunctional anti-apoptotic Bag-1 protein has important roles in apoptosis, proteasome-mediated degradation, transcriptional regulation, and intracellular signaling. Bag-1 promotes cell survival and proliferation, and is overexpressed in breast cancer. Therefore, Bag-1-targeted therapy might be a promising strategy to treat breast cancer. However, the effects of Bag-1 silencing in combination with conventional chemotherapeutic drugs on cell viability and major signaling pathways have not yet been fully investigated in breast cancer cells. In this study, we investigated the cytotoxic effects of Bag-1 silencing, alone and in combination with cisplatin or paclitaxel treatment, in MCF-7 breast cancer cells. Bag-1 knockdown by shRNA or siRNA transfection sensitized MCF-7 cells to apoptosis induced by cisplatin or paclitaxel. Combination of Bag-1 silencing and drug treatment more potently downregulated the pro-survival PI3K/Akt/mTOR and p44/42 mitogen activated protein kinase (MAPK) pathways, and more potently upregulated the stress-activated p38 and SAPK/JNK MAPK pathways. Bag-1-silenced drug-treated cells had also highly reduced proliferative capacity, downregulated cyclin-cyclin dependent kinase complexes and upregulated tumor suppressors p21 and Rb. These results overall indicated that Bag-1 silencing enhanced cisplatin- or paclitaxel-induced cytotoxicity through multiple pathways. In conclusion, Bag-1 targeted therapy might enhance the therapeutic potential of conventional anti-cancer drugs in the treatment of breast cancer.

Rationally designing antisense therapy to keep up with evolving bacterial resistance

Antisense molecules used as antibiotics offer the potential to keep up with acquired resistance, by redesigning the sequence of an antisense. Once bacteria acquire resistance by mutating the targeted sequence, new antisense can readily be designed by using sequence information of a target gene. However, antisense molecules require additional delivery vehicles to get into bacteria and be protected from degradation. Based on progress in the last few years it appears that, while redesigning or finding new delivery vehicle will be more difficult than redesigning the antisense cargo, it will perhaps be less difficult than finding new conventional small molecule antibiotics. In this study we propose a protocol that maximizes the combined advantages of engineered delivery vehicle and antisense cargo by decreasing the immediate growth advantage to the pathogen of mutating the entry mechanisms and increasing the advantage to the pathogen of antisense target mutations. Using this protocol, we show by computer simulation an appropriately designed antisense therapy can potentially be effective many times longer than conventional antibiotics before succumbing to resistance. While the simulations describe an in-vitro situation, based on comparison with other in-vitro studies on acquired resistance we believe the advantages of the combination antisense strategy have the potential to provide much more sustainability in vivo than conventional antibiotic therapy.

Bait-and-Switch Supramolecular Strategy To Generate Noncationic RNA-Polymer Complexes for RNA Delivery

RNA interference (RNAi) requires the intracellular delivery of RNA molecules to initiate the neutralization of targeted mRNA molecules, inhibiting the expression or translation of the targeted gene. Current polymers and lipids that are used to deliver RNA molecules are generally required to be positively charged, to achieve complexation with RNA and the cellular internalization. However, positive surface charge has been implicated as the reason for toxicity in many of these systems. Herein, we report a novel strategy to generate noncationic RNA-polymer complexes for RNA delivery with low cytotoxicity. We use an in situ electrostatic complexation using a methylated pyridinium group, which is simultaneously removed during the RNA binding step. The resultant complexes demonstrate successful knockdown in preimplantation mammalian embryos, thus providing a new approach for nucleic acid delivery.

Nanoparticle-Patterned Multicompartmental Chitosan Capsules for Oral Delivery of Oligonucleotides

Orally administered antisense therapy has been introduced as an effective approach for treating cancer in the gastrointestinal tract. However, its practical application has been limited by the instability of oligonucleotides and their inefficient delivery. To overcome these problems, we synthesized size-dependent, oligonucleotide nanoparticle-patterned chitosan/phytic acid (ODN/CS/PA) capsules with protective shields via a three-step process of self-assembly, nanoparticle encapsulation, and shell formation. The multicompartmental capsule size and oligonucleotide nanoparticle-loading pattern were controlled by applying different potentials during the electrostatic extrusion process used for nanoparticle encapsulation. Over 95% of encapsulated oligonucleotides were protected from nuclease digestion (DNase I) and, depending on their size, showed 40-75% protection against simulated gastric fluid. Their controlled release from capsules correlated with the cellular delivery of released nanoparticles and the inhibition of protein expression in cancer cells. Specifically, large capsules showed approximately 32-fold greater delivery to cancer cells than nonencapsulated nanoparticles. We also confirmed delivery of oligonucleotide nanoparticles to the small intestine and colon of rats following oral administration. These findings demonstrate that the multicompartmental ODN/CS/PA capsules can facilitate efficient oral delivery of oligonucleotides for cancer treatment.

STAT3 Inhibition Combined with CpG Immunostimulation Activates Antitumor Immunity to Eradicate Genetically Distinct Castration-Resistant Prostate Cancers

PURPOSE

Prostate cancers show remarkable resistance to emerging immunotherapies, partly due to tolerogenic STAT3 signaling in tumor-associated myeloid cells. Here, we describe a novel strategy combining STAT3 inhibition with Toll-like Receptor 9 (TLR9) stimulation to unleash immune response against prostate cancers regardless of the genetic background.

EXPERIMENTAL DESIGN

We developed and validated a conjugate of the STAT3 antisense oligonucleotide (ASO) tethered to immunostimulatory TLR9 agonist (CpG oligonucleotide) to improve targeting of human and mouse prostate cancer and myeloid immune cells, such as myeloid-derived suppressor cells (MDSC).

RESULTS

CpG-STAT3ASO conjugates showed improved biodistribution and potency of STAT3 knockdown in target cells in vitro and in vivo. Systemic administration of CpG-STAT3ASO (5 mg/kg) eradicated bone-localized, Ras/Myc-driven, and Pten^{pc -/-} Smad4^{pc -/-} Trp53^{c -/-} prostate tumors in the majority of treated mice. These antitumor effects were primarily immune-mediated and correlated with an increased ratio of CD8⁺ to regulatory T cells and reduced pSTAT3⁺/PD-L1⁺ MDSCs. Both innate and adaptive immunity contributed to systemic antitumor responses as verified by the depletion of Gr1⁺ myeloid cells and CD8⁺ and CD4⁺ T cells, respectively. Importantly, only the bifunctional CpG-STAT3ASO, but not control CpG oligonucleotides, STAT3ASO alone, or the coinjection of both oligonucleotides, succeeded in recruiting neutrophils and CD8⁺ T cells into tumors. Thus, the concurrence of TLR9 activation with STAT3 inhibition in the same cellular compartment is indispensable for overcoming tumor immune tolerance and effective antitumor immunity against prostate cancer.

CONCLUSIONS

The bifunctional, immunostimulatory, and tolerance-breaking design of CpG-STAT3ASO offers a blueprint for the development of effective and safer oligonucleotide strategies for treatment of immunologically "cold" human cancers.