Polyplex-mediated inhibition of chemokine receptor CXCR4 and chromatin-remodeling enzyme NCOA3 impedes pancreatic cancer progression and metastasis

Therapeutic Perspectives of HIV-Associated Chemokine Receptor (CCR5 and CXCR4) Antagonists in Carcinomas

The interaction between malignant cells and the tumor microenvironment is critical for tumor progression, and the chemokine ligand/receptor axes play a crucial role in this process. The CXCR4/CXCL12 and CCR5/CCL5 axes, both related to HIV, have been associated with the early (epithelial-mesenchymal transition and invasion) and late events (migration and metastasis) of cancer progression. In addition, these axes can also modulate the immune response against tumors. Thus, antagonists against the receptors of these axes have been proposed in cancer therapy. Although preclinical studies have shown promising results, clinical trials are needed to include these drugs in the oncological treatment protocols. New alternatives for these antagonists, such as dual CXCR4/CCR5 antagonists or combined therapy in association with immunotherapy, need to be studied in cancer therapy.

DNA-cloaked nanoparticles for tumor microenvironment-responsive activation

Although progress has been made in developing tumor microenvironment-responsive delivery systems, the list of cargo-releasing stimuli remains limited. In this study, we report DNA nanothread-cloaked nanoparticles for reactive oxygen species (ROS)-rich tumor microenvironment-responsive delivery systems. ROS is well known to strongly induce DNA fragmentation via oxidative stress. As a model anticancer drug, hydrophobic omacetaxine was entrapped in branched cyclam ligand-modified nanoparticles (BNP). DNA nanothreads were prepared by rolling-circle amplification and complexed to BNP, yielding DNA nanothread-cloaked BNP (DBNP). DBNP was unmasked by DNA nanothread-degrading ROS and culture supernatants of LNCaP cells. The size and zeta potential of DBNP were changed by ROS. In ROS^high LNCaP cells, but not in ROS^low fibroblast cells, the uptake of DBNP was higher than that of other nanoparticles. Molecular imaging revealed that DBNP exhibited greater distribution to tumor tissues, compared to other nanoparticles. Ex vivo mass spectrometry-based imaging showed that omacetaxine metabolites were distributed in tumor tissues of mice treated with DBNP. Intravenous administration of DBNP reduced the tumor volume by 80% compared to untreated tumors. Profiling showed that omacetaxine treatment altered the transcriptional profile. These results collectively support the feasibility of using polymerized DNA-masked nanoparticles for selective activation in the ROS-rich tumor microenvironment.

An Evaluation of CXCR4 Targeting with PAMAM Dendrimer Conjugates for Oncologic Applications

The chemokine receptor 4 (CXCR4) is a promising diagnostic and therapeutic target for the management of various cancers. CXCR4 has been utilized in immunotherapy, targeted drug delivery, and endoradiotherapy. Poly(amidoamine) [PAMAM] dendrimers are well-defined polymers with unique properties that have been used in the fabrication of nanomaterials for several biomedical applications. Here, we describe the formulation and pharmacokinetics of generation-5 CXCR4-targeted PAMAM (G5-X4) dendrimers. G5-X4 demonstrated an IC₅₀ of 0.95 nM to CXCR4 against CXCL12-Red in CHO-SNAP-CXCR4 cells. Single-photon computed tomography/computed tomography imaging and biodistribution studies of ¹¹¹In-labeled G5-X4 showed enhanced uptake in subcutaneous U87 glioblastoma tumors stably expressing CXCR4 with 8.2 ± 2.1, 8.4 ± 0.5, 11.5 ± 0.9, 10.4 ± 2.6, and 8.8 ± 0.5% injected dose per gram of tissue at 1, 3, 24, 48, and 120 h after injection, respectively. Specific accumulation of [¹¹¹In]G5-X4 in CXCR4-positive tumors was inhibited by the peptidomimetic CXCR4 inhibitor, POL3026. Our results demonstrate that while CXCR4 targeting is beneficial for tumor accumulation at early time points, differences in tumor uptake are diminished over time as passive accumulation takes place. This study further confirms the applicability of PAMAM dendrimers for imaging and therapeutic applications. It also emphasizes careful consideration of image acquisition and/or treatment times when designing dendritic nanoplatforms for tumor targeting.

Perfluorocarbon Nanoemulsions Enhance Therapeutic siRNA Delivery in the Treatment of Pulmonary Fibrosis

Local pulmonary administration of therapeutic siRNA represents a promising approach to the treatment of lung fibrosis, which is currently hampered by inefficient delivery. Development of perfluorooctylbromide (PFOB) nanoemulsions as a way of improving the efficiency of pulmonary polycation-based delivery of siRNA is reported. The results show that the polycation/siRNA/PFOB nanoemulsions are capable of efficiently silencing the expression of STAT3 and inhibiting chemokine receptor CXCR4-two validated targets in pulmonary fibrosis. Both in vitro and in vivo results demonstrate that the nanoemulsions improve mucus penetration and facilitate effective cellular delivery of siRNA. Pulmonary treatment of mice with bleomycin-induced pulmonary fibrosis shows strong inhibition of the progression of the disease and significant prolongation of animal survival. Overall, the study points to a promising local treatment strategy of pulmonary fibrosis.

Nanocarriers for pancreatic cancer imaging, treatments, and immunotherapies

Pancreatic tumors are highly desmoplastic and immunosuppressive. Delivery and distribution of drugs within pancreatic tumors are compromised due to intrinsic physical and biochemical stresses that lead to increased interstitial fluid pressure, vascular compression, and hypoxia. Immunotherapy-based approaches, including therapeutic vaccines, immune checkpoint inhibition, CAR-T cell therapy, and adoptive T cell therapies, are challenged by an immunosuppressive tumor microenvironment. Together, extensive fibrosis and immunosuppression present major challenges to developing treatments for pancreatic cancer. In this context, nanoparticles have been extensively studied as delivery platforms and adjuvants for cancer and other disease therapies. Recent advances in nanotechnology have led to the development of multiple nanocarrier-based formulations that not only improve drug delivery but also enhance immunotherapy-based approaches for pancreatic cancer. This review discusses and critically analyzes the novel nanoscale strategies that have been used for drug delivery and immunomodulation to improve treatment efficacy, including newly emerging immunotherapy-based approaches. This review also presents important perspectives on future research directions that will guide the rational design of novel and robust nanoscale platforms to treat pancreatic tumors, particularly with respect to targeted therapies and immunotherapies. These insights will inform the next generation of clinical treatments to help patients manage this debilitating disease and enhance survival rates.

Preferential siRNA delivery to injured kidneys for combination treatment of acute kidney injury

Acute kidney injury (AKI) is characterized by a sudden loss of renal function and is associated with high morbidity and mortality. Tumor suppressor p53 and chemokine receptor CXCR4 were both implicated in the AKI pathology. Here, we report on the development and evaluation of polymeric CXCR4 antagonist (PCX) siRNA carrier for selective delivery to injured kidneys in AKI. Our results show that PCX/siRNA nanoparticles (polyplexes) provide protection against cisplatin injury to tubule cells in vitro when both CXCR4 and p53 are inhibited. The polyplexes selectively accumulate and are retained in the injured kidneys in cisplatin and bilateral ischemia reperfusion injury models of AKI. Treating AKI with the combined CXCR4 inhibition and p53 gene silencing with the PCX/sip53 polyplexes improves kidney function and decreases renal damage. Overall, our results suggest that the PCX/sip53 polyplexes have a significant potential to enhance renal accumulation in AKI and deliver therapeutic siRNA.

Intraperitoneal siRNA Nanoparticles for Augmentation of Gemcitabine Efficacy in the Treatment of Pancreatic Cancer

Pancreatic ductal adenocarcinoma is a deadly disease with limited treatment options due to late diagnosis and resistance to conventional chemotherapy. Among emerging therapeutic targets, the CXCR4 chemokine receptor and polo-like kinase 1 (PLK1) play critical roles in the progression, metastasis, and chemoresistance of pancreatic cancer. Here, we tested the hypothesis that combining CXCR4 inhibition by a polymeric CXCR4 antagonist PAMD-CHOL with PLK1 knockdown by siRNA will enhance the therapeutic effect of gemcitabine (GEM) in the orthotopic model of metastatic pancreatic cancer. We formulated nanoparticles with cholesterol-modified PAMD and siPLK1 and found strong synergism when combined with GEM treatment in vitro in both murine and human pancreatic cancer cell lines. The biodistribution of the nanoparticles in orthotopic pancreatic cancer models revealed strong accumulation in primary and metastatic tumors, with limited hepatic disposition. The cholesterol-containing nanoparticles showed not only increased tumor accumulation than the cholesterol-lacking control but also deeper penetration into the tumors. In a therapeutic study in vivo, the triple combination of PAMD-CHOL/siPLK1 and GEM showed superior anticancer activity when compared with single and dual combination controls. In conclusion, PAMD-CHOL/siPLK1 nanoparticles synergistically enhance anticancer activity of GEM in pancreatic cancer and represent a promising addition to the treatment arsenal.

RNAi-Based Approaches for Pancreatic Cancer Therapy

Pancreatic cancer is one of the most lethal forms of cancer, predicted to be the second leading cause of cancer-associated death by 2025. Despite intensive research for effective treatment strategies and novel anticancer drugs over the past decade, the overall patient survival rate remains low. RNA interference (RNAi) is capable of interfering with expression of specific genes and has emerged as a promising approach for pancreatic cancer because genetic aberrations and dysregulated signaling are the drivers for tumor formation and the stromal barrier to conventional therapy. Despite its therapeutic potential, RNA-based drugs have remaining hurdles such as poor tumor delivery and susceptibility to serum degradation, which could be overcome with the incorporation of nanocarriers for clinical applications. Here we summarize the use of small interfering RNA (siRNA) and microRNA (miRNA) in pancreatic cancer therapy in preclinical reports with approaches for targeting either the tumor or tumor microenvironment (TME) using various types of nanocarriers. In these studies, inhibition of oncogene expression and induction of a tumor suppressive response in cancer cells and surrounding immune cells in TME exhibited a strong anticancer effect in pancreatic cancer models. The review discusses the remaining challenges and prospective strategies suggesting the potential of RNAi-based therapeutics for pancreatic cancer.

Gene silencing delivery systems for the treatment of pancreatic cancer: Where and what to target next?

Despite intensive research efforts and development of numerous new anticancer drugs and treatment strategies over the past decades, there has been only very limited improvement in overall patient survival and in effective treatment options for pancreatic cancer. Current chemotherapy improves survival in terms of months and death rates in pancreatic cancer patients are almost equivalent to incidence rates. It is imperative to develop new therapeutic approaches. Among them, gene silencing shows promise of effectiveness in both tumor cells and stromal cells by inhibiting tumor-promoting genes. This review summarizes potential targets for gene silencing in both pancreatic cancer cells and abundant stromal cells focusing on non-viral delivery systems for small RNAs and discusses the potential immunological implications. The review concludes with the importance of multifactorial therapy of pancreatic cancer.

Development and analysis of long non-coding RNA-associated competing endogenous RNA network for osteosarcoma metastasis

Background

Osteosarcoma is the primary bone malignant neoplasm that often develops metastasis. Increasing evidences have shown that non-coding RNAs (ncRNAs) relate to the progression of osteosarcoma. However, the ncRNAs’ roles in osteosarcoma metastasis are still unknown.

Methods

Differentially expressed (DE) RNAs were identified from Gene Expression Omnibus (GEO) database. Protein-protein interaction (PPI) of DE messenger RNAs (DEmRNAs) was built through STRING database. The target mRNAs and long ncRNAs (lncRNAs) of microRNAs (miRNA) were predicted through miRDB, Targetscan and Genecode databases, which then cross-checked with previously obtained DERNAs to construct competing endogenous RNA (ceRNA) network. All networks were visualized via Cytoscape and the hub RNAs were screened out through Cytoscape plug-in Cytohubba. The gene functional and pathway analyses were performed through DAVID and MirPath databases. The survival analyses of hub RNAs were obtained through Kaplan-Meier (KM) survival curves.

Results

Five hundred sixty-four DEmRNAs, 16 DElncRNAs and 22 DEmiRNAs were screened out. GO functional and KEGG pathway analyses showed that DERNAs were significantly associated with tumor metastasis. The ceRNA network including 6 lncRNAs, 55 mRNAs and 20 miRNAs were constructed and the top 10 hub RNAs were obtained. Above all, PI3K/AKT signaling pathway was identified as the most important osteosarcoma metastasis-associated pathway and its hub ceRNA module was constructed. The survival analyses showed that the RNAs in hub ceRNA module closely related to osteosarcoma patients’ prognosis.

Conclusions

The current study provided a new perspective on osteosarcoma metastasis. More importantly, the RNAs in hub ceRNA module might act as the novel therapeutic targets and prognostic factors for osteosarcoma patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41065-021-00174-0.

Cyclam-Modified Polyethyleneimine for Simultaneous TGFβ siRNA Delivery and CXCR4 Inhibition for the Treatment of CCl4-Induced Liver Fibrosis

BACKGROUND

Liver fibrosis is a chronic liver disease with excessive production of extracellular matrix proteins, leading to cirrhosis, hepatocellular carcinoma, and death.

PURPOSE

This study aimed at the development of a novel derivative of polyethyleneimine (PEI) that can effectively deliver transforming growth factor β (TGFβ) siRNA and inhibit chemokine receptor 4 (CXCR4) for TGFβ silencing and CXCR4 Inhibition, respectively, to treat CCl₄-induced liver fibrosis in a mouse model.

METHODS

Cyclam-modified PEI (PEI-Cyclam) was synthesized by incorporating cyclam moiety into PEI by nucleophilic substitution reaction. Gel electrophoresis confirmed the PEI-Cyclam polyplex formation and stability against RNAase and serum degradation. Transmission electron microscopy and zeta sizer were employed for the morphology, particle size, and zeta potential, respectively. The gene silencing and CXCR4 targeting abilities of PEI-Cyclam polyplex were evaluated by luciferase and CXCR4 redistribution assays, respectively. The histological and immunohistochemical staining determined the anti-fibrotic activity of PEI-Cyclam polyplex. The TGFβ silencing of PEI-Cyclam polyplex was authenticated by Western blotting.

RESULTS

The ¹H NMR of PEI-Cyclam exhibited successful incorporation of cyclam content onto PEI. The PEI-Cyclam polyplex displayed spherical morphology, positive surface charge, and stability against RNAse and serum degradation. Cyclam modification decreased the cytotoxicity and demonstrated CXCR4 antagonistic and luciferase gene silencing efficiency. PEI-Cyclam/siTGFβ polyplexes decreased inflammation, collagen deposition, apoptosis, and cell proliferation, thus ameliorating liver fibrosis. Also, PEI-Cyclam/siTGFβ polyplex significantly downregulated α-smooth muscle actin, TGFβ, and collagen type III.

CONCLUSION

Our findings validate the feasibility of using PEI-Cyclam as a siRNA delivery vector for simultaneous TGFβ siRNA delivery and CXCR4 inhibition for the combined anti-fibrotic effects in a setting of CCl₄-induced liver fibrosis.

Overlapping variants in the blood, tissues and cell lines for patients with intracranial meningiomas are predominant in stem cell-related genes

OBJECTIVE

Bulk tissue genomic analysis of meningiomas identified common somatic mutations, however, it often excluded blood-related variants. In contrast, genomic characterisation of primary cell lines that can provide critical information regarding growth and proliferation, have been rare. In our work, we identified the variants that are present in the blood, tissues and corresponding cell lines that are likely to be predictive, tumorigenic and progressive.

METHOD

Whole-exome sequencing was used to identify variants and distinguish related pathways that exist in 42 blood, tissues and corresponding cell lines (BTCs) samples for patients with intracranial meningiomas. Conventional sequencing was used for the confirmation of variants. Integrative analysis of the gene expression for the corresponding samples was utilised for further interpretations.

RESULTS

In total, 926 BTC variants were detected, implicating 845 genes. A pathway analysis of all BTC genes with damaging variants indicated the 'cell morphogenesis involved in differentiation' stem cell-related pathway to be the most frequently affected pathway. Concordantly, five stem cell-related genes, GPRIN2, ALDH3B2, ASPN, THSD7A and SIGLEC6, showed BTC variants in at least five of the patients. Variants that were heterozygous in the blood and homozygous in the tissues or the corresponding cell lines were rare (average: 1.3 ± 0.3%), and included variants in the RUNX2 and CCDC114 genes. An analysis comparing the variants detected only in tumours with aggressive features indicated a total of 240 BTC genes, implicating the 'homophilic cell adhesion via plasma membrane adhesion molecules' pathway, and identifying the stem cell-related transcription coactivator NCOA3/AIB1/SRC3 as the most frequent BTC gene. Further analysis of the possible impact of the poly-Q mutation present in the NCOA3 gene indicated associated deregulation of 15 genes, including the up-regulation of the stem cell related SEMA3D gene and the angiogenesis related VEGFA gene.

CONCLUSION

Stem cell-related pathways and genes showed high prevalence in the BTC variants, and novel variants in stem cell-related genes were identified for meningioma. These variants can potentially be used as predictive, tumorigenic and progressive biomarkers for meningioma.

Targeting pulmonary tumor microenvironment with CXCR4-inhibiting nanocomplex to enhance anti-PD-L1 immunotherapy

Anti-programmed cell death 1 ligand 1 (PD-L1) therapy is extraordinarily effective in select patients with cancer. However, insufficient lymphocytic infiltration, weak T cell-induced inflammation, and immunosuppressive cell accumulation in the tumor microenvironment (TME) may greatly diminish the efficacy. Here, we report development of the FX@HP nanocomplex composed of fluorinated polymerized CXCR4 antagonism (FX) and paclitaxel-loaded human serum albumin (HP) for pulmonary delivery of anti-PD-L1 small interfering RNA (siPD-L1) to treat orthotopic lung tumors. FX@HP induced T cell infiltration, increased expression of calreticulin on tumor cells, and reduced the myeloid-derived suppressor cells/regulatory T cells in the TME, thereby acting synergistically with siPD-L1 for effective immunotherapy. Our work suggests that the CXCR4-inhibiting nanocomplex decreases tumor fibrosis, facilitates T cell infiltration and relieves immunosuppression to modulate the immune process to improve the objective response rate of anti-PD-L1 immunotherapy.

Stromal Modulation and Treatment of Metastatic Pancreatic Cancer with Local Intraperitoneal Triple miRNA/siRNA Nanotherapy

Nanomedicines achieve tumor-targeted delivery mainly through enhanced permeability and retention (EPR) effect following intravenous (IV) administration. Unfortunately, the EPR effect is severely compromised in pancreatic cancer due to hypovascularity and dense desmoplastic stroma. Intraperitoneal (IP) administration may be an effective EPR-independent local delivery approach to target peritoneal tumors. Besides improved delivery, effective combination delivery strategies are needed to improve pancreatic cancer therapy by targeting both cancer cells and cellular interactions within the tumor stroma. Here, we described simple cholesterol-modified polymeric CXCR4 antagonist (PCX) nanoparticles (to block cancer-stroma interactions) for codelivery of anti-miR-210 (to inactivate stroma-producing pancreatic stellate cells (PSCs)) and siKRAS^G12D (to kill pancreatic cancer cells). IP administration delivered the nanoparticles to an orthotopic syngeneic pancreatic tumors as a result of preferential localization to the tumors and metastases with disrupted mesothelium and effective tumor penetration. The local IP delivery resulted in nearly 15-fold higher tumor accumulation than delivery by IV injection. Through antagonism of CXCR4 and downregulation of miR-210/KRAS^G12D, the triple-action nanoparticles favorably modulated desmoplastic tumor microenvironment via inactivating PSCs and promoting the infiltration of cytotoxic T cells. The combined therapy displayed improved therapeutic effect when compared with individual therapies as documented by the delayed tumor growth, depletion of stroma, reduction of immunosuppression, inhibition of metastasis, and prolonged survival. Overall, we present data that a local IP delivery of a miRNA/siRNA combination holds the potential to improve pancreatic cancer therapy.

Increased Survival by Pulmonary Treatment of Established Lung Metastases with Dual STAT3/CXCR4 Inhibition by siRNA Nanoemulsions

Lung metastasis is a common and deadly occurrence in many types of solid tumors. Chemokine receptor CXCR4 and transcription factor signal transducer and activator of transcription 3 (STAT3) are among potential therapeutic targets in lung metastatic cancer. Both CXCR4 and STAT3 play important roles in the proliferation, angiogenesis, and metastasis of cancer cells. Here, we report on the development of a pulmonary delivery (p.d.) system based on perfluorocarbon (PFC) nanoemulsions for combined delivery of a partially fluorinated polymeric CXCR4 antagonist (FM) and anti-STAT3 small interfering RNA (siRNA). We have prepared FM-stabilized PFC (FM@PFC) as a delivery system of therapeutic siRNA adsorbed on the surface of the emulsion. These FM@PFC/siRNA nanoemulsions inhibited both CXCR4 and STAT3, as demonstrated by effective anti-invasive ability in vitro and related antimetastatic activity in vivo. The combined nanoemulsions provided a comprehensive anticancer effect in the model of established lung metastasis of breast carcinoma, which was dependent on induction of cancer cell apoptosis, anti-angiogenic effect, anti-invasive activity, and overcoming of the immunosuppressive tumor microenvironment. Direct comparison with intravenous (i.v.) injection showed superior activity of pulmonary administration as indicated by significantly increased animal survival. Overall, this work established the suitability of the PFC nanoemulsions for p.d. of combination anticancer treatments and as a promising method to treat lung metastasis.

Use of polymeric CXCR4 inhibitors as siRNA delivery vehicles for the treatment of acute myeloid leukemia

Acute myeloid leukemia (AML) is the most common type of acute leukemia in adults and is associated with poor long-term survival often owing to relapse. Current treatments for AML are associated with considerable toxicity and are frequently not effective after relapse. Thus, it is important to develop novel therapeutic strategies. Short interfering RNA (siRNA)-based therapeutics targeting key oncogenes have been proposed as treatments for AML. We recently developed novel siRNA delivery polycations (PCX) based on AMD3100 (plerixafor), an FDA-approved inhibitor of the CXC chemokine receptor 4 (CXCR4). Inhibitors of CXCR4 have been shown to sensitize leukemia cells to chemotherapy. Therefore, PCX has the potential to target leukemia cells via two mechanisms: inhibition of CXCR4 and delivery of siRNAs against critical genes. In this report, we show that PCX exerts a cytotoxic effect on leukemia cells more effectively than other CXCR4 inhibitors, including AMD3100. In addition, we show that PCX can deliver siRNAs against the transcription factor RUNX1 to mouse and human leukemia cells. Overall, our study provides the first evidence that dual-function PCX/siRNA nanoparticles can simultaneously inhibit CXCR4 and deliver siRNAs, targeting key oncogenes in leukemia cells and that PCX/siRNA has clinical potential for the treatment of AML.

Cholangiocarcinoma therapy with nanoparticles that combine downregulation of MicroRNA-210 with inhibition of cancer cell invasiveness

Cholangiocarcinoma (CCA) is the second most common primary liver malignancy with extremely poor therapeutic outcome due to high drug resistance, widespread metastasis and lack of effective treatment options. CCA progression and metastasis are regulated by multiple biological factors including multiple miRNAs and chemokine receptor CXCR4. The goal of this study was to test if nanotherapeutic blockade of CXCR4 by polymeric CXCR4 antagonist (PCX) combined with inhibition of hypoxia-inducible miR-210 cooperatively enhances therapeutic efficacy in CCA through reducing invasiveness, inducing cell killing, and reversing drug resistance. Methods: We first tested the activity of PCX to inhibit migration of CCA cells. We then prepared PCX/anti-miRNA nanoparticles and analyzed their miRNA delivery efficacy and anticancer activity in vitro. Finally, in vivo biodistribution assay and anticancer activity study were performed in CCA tumor-bearing mice. Results: Our results show that PCX had a broad inhibitory effect on cell migration, effectively delivered anti-miR-210, and downregulated miR-210 expression in CCA cells. Combination PCX/anti-miR-210 nanoparticles showed cytotoxic activity towards CCA cells and reduced the number of cancer stem-like cells. The nanoparticles reversed hypoxia-induced drug resistance and sensitized CCA cells to standard gemcitabine and cisplatin combination treatment. Systemic intravenous treatment with the nanoparticles in a CCA xenograft model resulted in prominent combined antitumor activity. Conclusion: Our findings support PCX-based nanoparticles as a promising delivery platform of therapeutic miRNA in combination CCA therapies.

Promise of chemokine network-targeted nanoparticles in combination nucleic acid therapies of metastatic cancer

Chemokines and chemokine receptors play key roles in cancer progression and metastasis. Although multiple chemokines and chemokine receptors have been investigated, inhibition of CXCR4 emerged as one of the most promising approaches in combination cancer therapy, especially when focused on the metastatic disease. Small RNA molecules, such as small interfering RNA (siRNA) and microRNA (miRNA), represent new class of therapeutics for cancer treatment through RNA interference-mediated gene silencing. However, the clinical applicability of siRNA and miRNA is severely limited by the lack of effective delivery systems. There is a significant therapeutic potential for CXCR4-targeted nanomedicines in combination with the delivery of siRNA and miRNA in cancer. Recently developed CXCR4-targeted polymeric drugs and nanomedicines, including cyclam- and chloroquine-based polymeric CXCR4 antagonists are introduced here and their ability to deliver functional siRNA and miRNA is discussed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Cyclam-Modified PEI for Combined VEGF siRNA Silencing and CXCR4 Inhibition To Treat Metastatic Breast Cancer

Chemokine receptor CXCR4 plays an important role in cancer cell invasion and metastasis. Recent findings suggest that anti-VEGF therapies upregulate CXCR4 expression, which contributes to resistance to antiangiogenic therapies. Here, we report the development of novel derivatives of polyethylenimine (PEI) that effectively inhibit CXCR4 while delivering anti-VEGF siRNA. PEI was alkylated with different amounts of a CXCR4-binding cyclam derivative to prepare PEI-C. Modification with the cyclam derivatives resulted in a considerable decrease in cytotoxicity when compared with unmodified PEI. All the PEI-C showed significant CXCR4 antagonism and the ability to inhibit cancer cell invasion. Polyplexes of PEI-C prepared with siVEGF showed effective silencing of the VEGF expression in vitro. In vivo testing in a syngeneic breast cancer model showed promising antitumor and antimetastatic activity of the PEI-C/siVEGF polyplexes. Our data demonstrate the feasibility of using PEI-C as a carrier for simultaneous VEGF silencing and CXCR4 inhibition for enhanced antiangiogenic cancer therapies.

Conjugate Polyplexes with Anti-Invasive Properties and Improved siRNA Delivery In Vivo

This study reports on a simple method to prepare siRNA-polycation conjugate polyplexes by in situ thiol-disulfide exchange reaction. The conjugate polyplexes are prepared using thiol-terminated siRNA and a bioreducible branched polycationic inhibitor of the CXCR4 chemokine receptor (rPAMD). The rPAMD-SS-siRNA conjugate polyplexes exhibit improved colloidal stability and resistance against disassembly with heparin, serum, and physiological salt concentrations when compared with control conventional rPAMD/siRNA polyplexes. Coating the polyplexes with human serum albumin masks the positive surface charge and contributes to the enhanced in vitro gene silencing and improved safety in vivo. The conjugate polyplexes display improved in vivo reporter gene silencing following intravenous injection in tumor-bearing mice. Because the conjugate polyplexes retained the ability of rPAMD to inhibit CXCR4 and restrict cancer cell invasion, the developed systems show promise for future combination anti-metastatic siRNA therapies of cancer.

MUC4 mucin- a therapeutic target for pancreatic ductal adenocarcinoma

INTRODUCTION

Pancreatic cancer (PC) is characterized by mucin overexpression. MUC4 is the most differentially overexpressed membrane-bound mucin that plays a functional role in disease progression and therapy resistance. Area covered: We describe the clinicopathological significance of MUC4, summarize mechanisms contributing to its deregulated expression, review preclinical studies aimed at inhibiting MUC4, and discuss how MUC4 overexpression provides opportunities for developing targeted therapies. Finally, we discuss the challenges for developing MUC4-based therapeutics, and identify areas where efforts should be directed to effectively exploit MUC4 as a therapeutic target for PC. Expert opinion: Studies demonstrating that abrogation of MUC4 expression reduces proliferation and metastasis of PC cells and enhances sensitivity to therapeutic agents affirm its utility as a therapeutic target. Emerging evidence also supports the suitability of MUC4 as a potential immunotherapy target. However, these studies have been limited to in vitro, ex vivo or in vivo approaches using xenograft tumors in immunodeficient murine models. For translational relevance, MUC4-targeted therapies should be evaluated in murine models with intact immune system and accurate tumor microenvironment. Additionally, future studies evaluating MUC4 as a target for immunotherapy must entail characterization of immune response in PC patients and investigate its association with immunosuppression and survival.

Self-immolative nanoparticles for simultaneous delivery of microRNA and targeting of polyamine metabolism in combination cancer therapy

Combination of anticancer drugs with therapeutic microRNA (miRNA) has emerged as a promising anticancer strategy. However, the promise is hampered by a lack of desirable delivery systems. We report on the development of self-immolative nanoparticles capable of simultaneously delivering miR-34a mimic and targeting dysregulated polyamine metabolism in cancer. The nanoparticles were prepared from a biodegradable polycationic prodrug, named DSS-BEN, which was synthesized from a polyamine analog N1,N11-bisethylnorspermine (BENSpm). The nanoparticles were selectively disassembled in the cytoplasm where they released miRNA. Glutathione (GSH)-induced degradation of self-immolative linkers released BENSpm from the DSS-BEN polymers. MiR-34a mimic was effectively delivered to cancer cells as evidenced by upregulation of intracellular miR-34a and downregulation of Bcl-2 as one of the downstream targets of miR-34a. Intracellular BENSpm generated from the degraded nanoparticles induced the expression of rate-limiting enzymes in polyamine catabolism (SMOX, SSAT) and depleted cellular natural polyamines. Simultaneous regulation of polyamine metabolism and miR-34a expression by DSS-BEN/miR-34a not only enhanced cancer cell killing in cultured human colon cancer cells, but also improved antitumor activity in vivo. The reported findings validate the self-immolative nanoparticles as delivery vectors of therapeutic miRNA capable of simultaneously targeting dysregulated polyamine metabolism in cancer, thereby providing an elegant and efficient approach to combination nanomedicines.