Aspirin-/TMZ-coloaded microspheres exert synergistic antiglioma efficacy via inhibition of β-catenin transactivation

Exploiting Nanomedicine for Cancer Polychemotherapy: Recent Advances and Clinical Applications

The most important limitations of chemotherapeutic agents are severe side effects and the development of multi-drug resistance. Recently, the clinical successes achieved with immunotherapy have revolutionized the treatment of several advanced-stage malignancies, but most patients do not respond and many of them develop immune-related adverse events. Loading synergistic combinations of different anti-tumor drugs in nanocarriers may enhance their efficacy and reduce life-threatening toxicities. Thereafter, nanomedicines may synergize with pharmacological, immunological, and physical combined treatments, and should be increasingly integrated in multimodal combination therapy regimens. The goal of this manuscript is to provide better understanding and key considerations for developing new combined nanomedicines and nanotheranostics. We will clarify the potential of combined nanomedicine strategies that are designed to target different steps of the cancer growth as well as its microenvironment and immunity interactions. Moreover, we will describe relevant experiments in animal models and discuss issues raised by translation in the human setting.

Advantages and drawbacks of dexamethasone in glioblastoma multiforme

The most widespread, malignant, and deadliest type of glial tumor is glioblastoma multiforme (GBM). Despite radiation, chemotherapy, and radical surgery, the median survival of afflicted individuals is about 12 months. Unfortunately, existing therapeutic interventions are abysmal. Dexamethasone (Dex), a synthetic glucocorticoid, has been used for many years to treat brain edema and inflammation caused by GBM. Several investigations have recently shown that Dex also exerts antitumoral effects against GBM. On the other hand, more recent disputed findings have questioned the long-held dogma of Dex treatment for GBM. Unfortunately, steroids are associated with various undesirable side effects, including severe immunosuppression and metabolic changes like hyperglycemia, which may impair the survival of GBM patients. Current ideas and concerns about Dex's effects on GBM cerebral edema, cell proliferation, migration, and its clinical outcomes were investigated in this study.

Nanoparticle-based drug delivery systems in cancer: A focus on inflammatory pathways

It has become necessary to accept the clinical reality of therapeutic agents targeting the cancer-associated immune system. In recent decades, several investigations have highlighted the role of inflammation in cancer development. It has now been recognized that inflammatory cells secrete mediators, including enzymes, chemokines, and cytokines. These secreted substances produce an inflammatory microenvironment that is critically involved in cancer growth. Inflammation may enhance genomic instability leading to DNA damage, activation of oncogenes, or compromised tumor suppressor activity, all of which may promote various phases of carcinogenesis. Conventional cancer treatment includes surgery, radiation, and chemotherapy. However, treatment failure occurs because current strategies are unable to achieve complete local control due to metastasis. Nanoparticles (NPs) are a broad spectrum of drug carriers typically below the size of 100 nm, targeting tumor sites while reducing off-target consequences. More importantly, NPs can stimulate innate and adaptive immune systems in the tumor microenvironment (TME); hence, they induce a cancer-fighting immune response. Strikingly, targeting cancer cells with NPs helps eliminate drug resistance and tumor recurrence, as well as prevents inflammation. Throughout this review, we provide recent data on the role of inflammation in cancer and explore nano-therapeutic initiatives to target significant mediators, for example, nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α), and interleukins (ILs) associated with cancer-related inflammation, to escort the immunomodulators to cancer cells and associated systemic compartments. We also highlight the necessity of better identifying inflammatory pathways in cancer pathophysiology to develop effective treatment plans.

Nanotherapeutics Overcoming the Blood-Brain Barrier for Glioblastoma Treatment

Glioblastoma (GBM) is the most common malignant primary brain tumor with a poor prognosis. The current standard treatment regimen represented by temozolomide/radiotherapy has an average survival time of 14.6 months, while the 5-year survival rate is still less than 5%. New therapeutics are still highly needed to improve the therapeutic outcome of GBM treatment. The blood-brain barrier (BBB) is the main barrier that prevents therapeutic drugs from reaching the brain. Nanotechnologies that enable drug delivery across the BBB hold great promise for the treatment of GBM. This review summarizes various drug delivery systems used to treat glioma and focuses on their approaches for overcoming the BBB to enhance the accumulation of small molecules, protein and gene drugs, etc. in the brain.

Nanocarrier-based drug combination therapy for glioblastoma

The current achievements in treating glioblastoma (GBM) patients are not sufficient because many challenges exist, such as tumor heterogeneity, the blood brain barrier, glioma stem cells, drug efflux pumps and DNA damage repair mechanisms. Drug combination therapies have shown increasing benefits against those challenges. With the help of nanocarriers, enhancement of the efficacy and safety could be gained using synergistic combinations of different therapeutic agents. In this review, we will discuss the major issues for GBM treatment, the rationales of drug combinations with or without nanocarriers and the principle of enhanced permeability and retention effect involved in nanomedicine-based tumor targeting and promising nanodiagnostics or -therapeutics. We will also summarize the recent progress and discuss the clinical perspectives of nanocarrier-based combination therapies. The goal of this article was to provide better understanding and key considerations to develop new nanomedicine combinations and nanotheranostics options to fight against GBM.

Local strategies and delivery systems for the treatment of malignant gliomas

Glioma is one of the most common type of malignant tumours with high morbidity and mortality rates. Due to the particular features of the brain, such as blood-brain barrier or blood-tumour barrier, therapeutic agents are ineffective by systemic administration. The tumour inevitably recurs and devitalises patients. Herein, an overview of the localised gliomas treatment strategies is provided, including direct intratumoural/intracerebral injection, convection-enhanced delivery, and the implant of biodegradable polymer systems. The advantages and disadvantages of each therapy are discussed. Subsequently, we have reviewed the recent developments of therapeutic delivery systems aimed at transporting sufficient amounts of antineoplastic drugs into the brain tumour sites while minimising the potential side effects. To treat gliomas, localised and controlled delivery of drugs at their desired site of action is preferred as it reduces toxicity and increases treatment efficiency. Simultaneously, various drug delivery systems (DDS) have been used to enhance drug delivery to the brain. Use of non-conventional DDS for localised therapy has greatly expanded the spectrum of drugs available for the treatment of malignant tumours. Use smart DDS via localised delivery strategies, in combination with radiotherapy and multiple drug loading would serve as a promising approach to treat gliomas.

Survival as a Function of Nonsteroidal Anti-inflammatory Drug Use in Patients with Glioblastoma

Background Findings of both case control and in vitro investigations suggest that non-steroidal anti-inflammatory drugs (NSAIDs) may play a beneficial role in the occurrence, growth, and subsistence of glioblastoma multiforme (GBM) brain tumor in humans. Objective In the present retrospective cohort study, we assessed the impact of NSAID use on survival in patients diagnosed with and treated for GBM brain tumors. Methods The impact of NSAID use and six other potential prognostic indicators of survival were assessed in 71 patients treated for GBM brain tumors from February 2011 to June 2016. Survival analysis and cross-tabulation analyses were performed to examine the potential relationship between NSAID use and occurrence of intracranial hemorrhage over the course of treatment for GBM. Results Kaplan-Meier analysis revealed no significant difference in survival between patients with and without NSAID use (p = 0.75; 95% CI: 10.12, 18.13). Multiple Cox regression analysis identified only treatment with chemotherapy as imposing any statistically significant effect on survival (Hazard Ratio (HR) = 3.31; p < 0.001; 95% CI: 1.80, 6.07). Cross-tabulation revealed no significant effect of NSAID use on occurrence of hemorrhage during treatment, X² (2, N = 71) = 0.65, p_2-Sided = 0.42, (Fisher's Exact Test: p2-sided = 0.56, p1-sided = 0.31). Conclusion These results suggest that history of NSAID use is not a determinant of survival in GBM patients. More rigorous, prospective investigations of the effect of NSAID use on tumor progression are necessary before the utility of this family of drugs in the treatment of GBM can be adequately appraised.

Multiregion whole-exome sequencing of matched primary and metastatic tumors revealed genomic heterogeneity and suggested polyclonal seeding in colorectal cancer metastasis

Background

Distant metastasis accounts for 90% of deaths from colorectal cancer (CRC). Genomic heterogeneity has been reported in various solid malignancies, but remains largely under-explored in metastatic CRC tumors, especially in primary to metastatic tumor evolution.

Patients and methods

We conducted high-depth whole-exome sequencing in multiple regions of matched primary and metastatic CRC tumors. Using a total of 28 tumor, normal, and lymph node tissues, we analyzed inter- and intra-individual heterogeneity, inferred the tumor subclonal architectures, and depicted the subclonal evolutionary routes from primary to metastatic tumors.

Results

CRC has significant inter-individual but relatively limited intra-individual heterogeneity. Genomic landscapes were more similar within primary, metastatic, or lymph node tumors than across these types. Metastatic tumors exhibited less intratumor heterogeneity than primary tumors, indicating that single-region sequencing may be adequate to identify important metastasis mutations to guide treatment. Remarkably, all metastatic tumors inherited multiple genetically distinct subclones from primary tumors, supporting a possible polyclonal seeding mechanism for metastasis. Analysis of one patient with the trio samples of primary, metastatic, and lymph node tumors supported a mechanism of synchronous parallel dissemination from the primary to metastatic tumors that was not mediated through lymph nodes.

Conclusions

In CRC, metastatic tumors have different but less heterogeneous genomic landscapes than primary tumors. It is possible that CRC metastasis is, at least partly, mediated through a polyclonal seeding mechanism. These findings demonstrated the rationale and feasibility for identifying and targeting primary tumor-derived metastasis-potent subclones for the prediction, prevention, and treatment of CRC metastasis.

Aspirin inhibits the SHH/GLI1 signaling pathway and sensitizes malignant glioma cells to temozolomide therapy

Aberrant activation of sonic hedgehog (SHH)/glioma-associated oncogene homolog 1 (GLI1) pathway plays an important role in the tumorigenicity of malignant glioma cells and resistance to temozolomide (TMZ). Here we investigated the aspirin's antineoplastic molecular route by targeting SHH/GLI1 pathway and examined the feasibility of aspirin combined with TMZ therapy. Western blot and quantitative real-time polymerase chain reaction (qRT-PCR) revealed that the activity of the SHH/GLI1 pathway was strongly inhibited by aspirin. Aspirin acted as the glioma growth-inhibitory and pro-apoptosis roles by inhibiting the SHH/GLI1 pathway and reprogramming the epithelial to mesenchymal transition (EMT). The immunofluorescence assay showed aspirin could prevent the nuclear translocation of GLI1 to inhibit its transcriptional regulation. The stable lentiviral overexpression of GLI1 reversed the DNA double strand breaks (DSBs) caused by the GANT61 and TMZ. Furthermore, aspirin combined with TMZ enhanced chemosensitivity and GLI1-induced chemoprotection was partly blocked by aspirin in vitro and in vivo. Collectively, aspirin has a therapeutic potential for SHH/GLI1 targeted therapy against glioma cells. Acquired activation of GLI1 protects glioma cells against TMZ therapy. Impairment of DNA DSBs repair activity might be involved in the route of aspirin-induced chemosensitivity. Combined aspirin with TMZ may be a promising strategy against malignant glioma.

FoxO3a induces temozolomide resistance in glioblastoma cells via the regulation of β-catenin nuclear accumulation

Glioblastoma multiforme (GBM), the most common malignant brain tumor, is currently treated with temozolomide (TMZ), but GBM often exhibits resistance to TMZ. Although several mechanisms underlying GBM resistance to TMZ have been identified, these mechanisms are yet to fully explain how GBM gains resistance to TMZ. Our previous work has shown that FoxO3a, a member of the FoxO subfamily of transcription factors, promotes glioma cell proliferation and invasion. In this study, we sought to determine whether FoxO3a participates in TMZ resistance in GBM cells. Parental cell lines (also designated as sensitive cell lines) U87-MG and U251-MG, as well as the corresponding resistant cell lines U87-TR and U251-TR (generated by repeated TMZ treatments), were subjected to western blot analysis. Our results showed that the resistant cells (both U87-TRand U251-TR) exhibited higher levels of FoxO3a and β-catenin relative to their corresponding sensitive counterparts. Depletion of FoxO3a in the resistant cells enhanced the cytotoxic effect of TMZ. Further investigation showed that FoxO3a depletion did not affect the total protein level of β-catenin, but otherwise markedly reduced the nuclear β-catenin level. Taken together, these findings strongly support that FoxO3a renders GBM cells resistant to TMZ treatment, at least in part, through the regulation of β-catenin nuclear accumulation.

GGNBP2 Suppresses the Proliferation, Invasion, and Migration of Human Glioma Cells

Gliomas are the most common and aggressive type of primary adult brain tumors. Although GGNBP2 has previously been considered to be a tumor suppressor gene, little is known about the association between GGNBP2 and glioma. In this study, we clearly demonstrated that GGNBP2 was downexpressed in glioma tissues, and its downexpression is related to the pathological grade and overall survival of patients with gliomas. Overexpression of GGNBP2 suppressed the proliferation, migration, and invasion of glioma cells. Mechanistically, we demonstrated that the PI3K/Akt and Wnt/β-catenin signaling pathways were suppressed by GGNBP2 overexpression. In contrast, knockdown of GGNBP2 has precisely the opposite effect. Collectively, these data indicate that GGNBP2 shows tumor suppressive activity in human glioma cells and may stand out as a potential therapeutic target for glioma.

Downregulation of MicroRNA-320d predicts poor overall survival and promotes the growth and invasive abilities in glioma

Previous studies have demonstrated that miRNAs play an important role in tumor development and progression. The role of miR-320d has been studied in several cancers except for glioma. The aim of the study was to investigate the expression levels, biological function, and mechanism of miR-320d in glioma. The expression levels of miR-320d were detected in glioma tissues and cell lines (U87 and U251) by RT-qPCR. Cell proliferation, colony formation, apoptosis, cell cycle, and transwell assays were performed in glioma cell lines transfected with miR-320d mimics or controls to evaluate the effects of miR-320d in vitro. The expression levels of invasive-related proteins were determined by Western blot analysis. Results showed that the expression of miR-320d was significantly decreased in glioma tissues and cell lines. Overexpression of miR-320d could significantly suppress cell growth, migration and invasion, and induced cell apoptosis as well as cell cycle at G0/G1 arrest in U87 and U251 cell lines. Additionally, expression levels of MMP-2, MMP-9, N-cadherin, and integrin-β1 reduced, while E-cadherin increased in miR-320d mimic group. Overall, this study is the first to demonstrate that miR-320d may serve as an independent prognostic factor, indicating that miR-320d is a biomarker for prognosis and therapy in glioma.

Proteomic level changes associated with S3I201 treated U87 glioma cells

Glioblastoma multiforme is Grade IV brain tumor associated with high mortality and limited therapeutics. Signal Transducer and Activator of Transcription 3 (STAT3) is persistently active in several cancers including gliomas, and plays a major role in disease progression and survival of glioma patients, thus being a potential therapeutic target for treatment. S3I201 and its analogs inhibit the transcriptional functions of STAT3 and reduce growth of tumor tissues. Here we have studied proteomic alteration associated with S3I201 treated U87 cells using 2-DE and Isobaric tags for relative and absolute quantitation coupled with mass spectrometry. This analysis revealed 136 differentially expressed proteins which were functionally classified with gene ontology analysis. Results showed metabolism, apoptosis, cytoskeletal behaviour, cell redox homeostasis and immune response as the most affected biological processes on S3I201 treatment. Apoptosis-inducing factor 1 mitochondrial, cyclophilin A and chloride intra-cellular channel protein 1 were found to be up-regulated which possibly contributes to its anti-tumorigenic function. Several glycolytic enzymes like phosphoglycerate mutase 1 were also found to be up-regulated and its expression was validated using immunoblot. Conclusively, our study shows the downstream effects of S3I201 in U87 glioma cells and suggests its therapeutic potential.

SIGNIFICANCE

Gliomas with constitutive expression can be treated with STAT3 inhibitors. S3I201, a STAT3 inhibitor, reduces the growth of glioma cells thus could be studied further for its application as anti-glioma agent. This study investigated proteomic alteration associated with S3I201 in U87 cells using complementary proteomic approaches, and our findings suggest that S3I201 influences central metabolism, apoptosis, cytoskeletal behaviour, cell redox homeostasis and immune response as the most affected biological processes which altogether contribute to its anti-tumorigenic activity. Several proteins were identified which may serve as prognostic or predictive markers in GBM. Apoptosis-inducing factor 1 mitochondrial and cyclophilin A were identified as potential therapeutic targets and further investigations on these candidates may facilitate therapeutic development and suggests that GBM therapy can be improved by targeting cellular metabolism and by using immunotherapy.

HOXA13 is a potential GBM diagnostic marker and promotes glioma invasion by activating the Wnt and TGF-β pathways

Homeobox (HOX) genes, including HOXA13, are involved in human cancer. We found that HOXA13 expression was associated with glioma grade and prognosis. Bioinformatics analysis revealed that most of the HOXA13-associated genes were enriched in cancer-related signaling pathways and mainly involved in the regulation of transcription. We transfected four glioma cell lines with Lenti-si HOXA13. HOXA13 increased cell proliferation and invasion and inhibited apoptosis. HOXA13 decreased β-catenin, phospho-SMAD2, and phospho-SMAD3 in the nucleus and increased phospho-β-catenin in the cytoplasm. Furthermore, downregulation of HOXA13 in orthotopic tumors decreased tumor growth. We suggest that HOXA13 promotes glioma progression in part via Wnt- and TGF-β-induced EMT and is a potential diagnostic biomarker for glioblastoma and an independent prognostic factor in high-grade glioma.

The novel agent phospho-glycerol-ibuprofen-amide (MDC-330) inhibits glioblastoma growth in mice: an effect mediated by cyclin D1

Given that glioblastoma multiforme (GBM) is associated with poor prognosis, new agents are urgently needed. We developed phospho-glycerol-ibuprofen-amide (PGIA), a novel ibuprofen derivative, and evaluated its safety and efficacy in preclinical models of GBM, and its mechanism of action using human GBM cells and animal tumor models. Furthermore, we explored whether formulating PGIA in polymeric nanoparticles could enhance its levels in the brain. PGIA was 3.7- to 5.1-fold more potent than ibuprofen in suppressing the growth of human GBM cell lines. PGIA 0.75× IC50 inhibited cell proliferation by 91 and 87% in human LN-229 and U87-MG GBM cells, respectively, and induced strong G1/S arrest.In vivo, compared with control, PGIA reduced U118-MG and U87-MG xenograft growth by 77 and 56%, respectively (P< 0.05), and was >2-fold more efficacious than ibuprofen. Normal human astrocytes were resistant to PGIA, indicating selectivity. Mechanistically, PGIA reduced cyclin D1 levels in a time- and concentration-dependent manner in GBM cells and in xenografts. PGIA induced cyclin D1 degradation via the proteasome pathway and induced dephosphorylation of GSK3β, which was required for cyclin D1 turnover. Furthermore, cyclin D1 overexpression rescued GBM cells from the cell growth inhibition by PGIA. Moreover, the formulation of PGIA in poly-(L)-lactic acid poly(ethylene glycol) polymeric nanoparticles improved its pharmacokinetics in mice, delivering PGIA to the brain. PGIA displays strong efficacy against GBM, crosses the blood-brain barrier when properly formulated, reaching the target tissue, and establishes cyclin D1 as an important molecular target. Thus, PGIA merits further evaluation as a potential therapeutic option for GBM.

Sustained release of hydrophilic drug from polyphosphazenes/poly(methyl methacrylate) based microspheres and their degradation study

Drug delivery system is referred as an approach to deliver the therapeutic agents to the target site safely in order to achieve the maximum therapeutic effects. In this perspective, synthesis of three new polyphosphazenes and their blend fabrication system with poly(methyl methacrylate) is described and characterized with (1)H NMR, (31)P NMR, GPC and DSC. Furthermore, these novel blends were used to fabricate microspheres and evaluated for sustain release of hydrophilic drug (aspirin as model drug). Microspheres of the two blends showed excellent encapsulation efficacy (about 93%), controlled burst release (2.3% to 7.93%) and exhibited sustain in vitro drug release (13.44% to 32.77%) up to 218 h. At physiological conditions, the surface degradation of microspheres and diffusion process controlled the drug release sustainability. Furthermore, it was found that the degree of porosity was increased with degradation and the resulting porous network was responsible for water retention inside the microspheres. The percentage water retention was found to be interrelated with degradation time and percentage drug release.

Efficient delivery of therapeutic miRNA nanocapsules for tumor suppression

miRNA nanocapsules are synthesized with enhanced stability for miRNA delivery with high transduction efficiency, offering a novel class of miRNA vectors for cancer therapy.

BASI, a potent small molecular inhibitor, inhibits glioblastoma progression by targeting microRNA-mediated β-catenin signaling

BACKGROUND AND AIMS

The nuclear localization of β-catenin, a mediator of canonical Wnt signaling, has been indicated in a variety of cancers and is frequently related to tumor progression and metastasis. Therefore, targeting β-catenin is an attractive therapeutic strategy for cancers.

METHODS

Herein, we identified a natural, small molecule inhibitor of β-catenin signaling, BASI, and evaluated its therapeutic efficacy both in vitro and in orthotopic mouse models of glioma.

RESULTS

BASI significantly suppressed proliferation and invasion and induced apoptosis in glioblastoma cells and resulted in the remarkable attenuation of orthotopic tumor growth in vivo. Furthermore, we found that BASI altered the expression of several microRNAs, which mediated the posttranscriptional silencing of β-catenin expression either directly or indirectly through a von Hippel-Lindau (VHL)-mediated β-catenin degradation pattern.

CONCLUSIONS

Taken together, our findings offer preclinical validation of BASI as a promising new type of β-catenin inhibitor with a mechanism of inhibition that has broad potential for the improved treatment of glioblastoma.

AJAP1 is dysregulated at an early stage of gliomagenesis and suppresses invasion through cytoskeleton reorganization

AIMS

Down-regulation of AJAP1 in glioblastoma multiforme (GBM) has been reported. However, the expression profiles of AJAP1 in gliomas and the underlying mechanisms of AJAP1 function on invasion are still poorly understood.

METHODS

The gene profiles of AJAP1 in glioma patients were studied among four independent cohorts. Confocal imaging was used to analyze the AJAP1 localization. After AJAP1 overexpression in GBM cell lines, cellular polarity, cytoskeleton distribution, and antitumor effect were investigated in vitro and in vivo.

RESULTS

AJAP1 expression was significantly decreased in gliomas compared with normal brain in REMBRANDT and CGCA cohorts. Additionally, low AJAP1 expression was associated with worse survival in GBMs in REMBRANDT and TCGA U133A cohorts and was significantly associated with classical and mesenchymal subtypes of GBMs among four cohorts. Confocal imaging indicated AJAP1 localized in cell membranes in low-grade gliomas and AJAP1-overexpressing GBM cells, but difficult to assess in high-grade gliomas due to its absence. AJAP1 overexpression altered the cytoskeleton and cellular polarity in vitro and inhibited the tumor growth in vivo.

CONCLUSIONS

AJAP1 is dysregulated at an early stage of gliomagenesis and may suppress glioma cell invasion and proliferation, which suggests that AJAP1 may be a potential diagnostic and prognostic marker for gliomas.

Star-branched amphiphilic PLA-b-PDMAEMA copolymers for co-delivery of miR-21 inhibitor and doxorubicin to treat glioma

The combined treatment of chemotherapeutant and microRNA (miR) has been proven to be a viable strategy for enhancing chemosensitivity due to its synergistic effect for tumor therapy. However, the co-delivery of drugs and genes remains a major challenge as they lack efficient co-delivery carriers. In this study, three amphiphilic star-branched copolymers comprising polylactic acid (PLA) and polydimethylaminoethyl methacrylate (PDMAEMA) with AB3, (AB3)2,and (AB3)3 molecular architectures were synthesized respectively by a combination of ring-opening polymerization, atom transfer radical polymerization, and click chemistry via an "arm-first" approach. The star copolymers possessed a low critical micelle concentration (CMC) and formed nano-sized micelles with positive surface charges in water as well as exhibiting a much lower cytotoxicity than PEI 25 kDa. Nevertheless, their gene transfection efficiency and tumor inhibition ability showed a remarkable dependence on their molecular architecture. The (AB3)3 architecture micelle copolymer exhibited the highest transfection efficiency, about 2.5 times higher than PEI. In addition, after co-delivering DOX and miR-21 inhibitor (miR-21i) into LN229 glioma cells, the micelles could mediate escaping miR-21i from lysosome degradation and the release of DOX to the nucleus, which significantly decreased the miR-21 expression. Moreover, co-delivery of DOX and miR-21i surprisingly exhibited an anti-proliferative efficiency compared with DOX or the miR-21i treatment alone. These results demonstrated that amphiphilic star-branched copolymers are highly promising for their combinatorial delivery of genes and hydrophobic therapeutants.