AKT2 siRNA delivery with amphiphilic-based polymeric micelles show efficacy against cancer stem cells

A Novel Tendon Injury Model, Induced by Collagenase Administration Combined with a Thermo-Responsive Hydrogel in Rats, Reproduces the Pathogenesis of Human Degenerative Tendinopathy

Patellar tendinopathy is a common clinical problem, but its underlying pathophysiology remains poorly understood, primarily due to the absence of a representative experimental model. The most widely used method to generate such a model is collagenase injection, although this method possesses limitations. We developed an optimized rat model of patellar tendinopathy via the ultrasound-guided injection of collagenase mixed with a thermo-responsive Pluronic hydrogel into the patellar tendon of sixty male Wistar rats. All analyses were carried out at 3, 7, 14, 30, and 60 days post-injury. We confirmed that our rat model reproduced the pathophysiology observed in human patients through analyses of ultrasonography, histology, immunofluorescence, and biomechanical parameters. Tendons that were injured by the injection of the collagenase-Pluronic mixture exhibited a significant increase in the cross-sectional area (p < 0.01), a high degree of tissue disorganization and hypercellularity, significantly strong neovascularization (p < 0.01), important changes in the levels of types I and III collagen expression, and the organization and presence of intra-tendinous calcifications. Decreases in the maximum rupture force and stiffness were also observed. These results demonstrate that our model replicates the key features observed in human patellar tendinopathy. Collagenase is evenly distributed, as the Pluronic hydrogel prevents its leakage and thus, damage to surrounding tissues. Therefore, this model is valuable for testing new treatments for patellar tendinopathy.

Optimization of Statin-Loaded Delivery Nanoparticles for Treating Chronic Liver Diseases by Targeting Liver Sinusoidal Endothelial Cells

In this study, we developed functionalized polymeric micelles (FPMs) loaded with simvastatin (FPM-Sim) as a drug delivery system to target liver sinusoidal endothelial cells (LSECs) for preserving liver function in chronic liver disease (CLD). Polymeric micelles (PMs) were functionalized by coupling peptide ligands of LSEC membrane receptors CD32b, CD36 and ITGB3. Functionalization was confirmed via spectroscopy and electron microscopy. In vitro and in vivo FPM-Sim internalization was assessed by means of flow cytometry in LSECs, hepatocytes, Kupffer and hepatic stellate cells from healthy rats. Maximum tolerated dose assays were performed in healthy mice and efficacy studies of FPM-Sim were carried out in bile duct ligation (BDL) and thioacetamide (TAA) induction rat models of cirrhosis. Functionalization with the three peptide ligands resulted in stable formulations with a greater degree of in vivo internalization in LSECs than non-functionalized PMs. Administration of FPM-Sim in BDL rats reduced toxicity relative to free simvastatin, albeit with a moderate portal-pressure-lowering effect. In a less severe model of TAA-induced cirrhosis, treatment with FPM-CD32b-Sim nanoparticles for two weeks significantly decreased portal pressure, which was associated with a reduction in liver fibrosis, lower collagen expression as well as the stimulation of nitric oxide synthesis. In conclusion, CD32b-FPM stands out as a good nanotransporter for drug delivery, targeting LSECs, key inducers of liver injury.

Intracellular Delivery of Anti-Kirsten Rat Sarcoma Antibodies Mediated by Polymeric Micelles Exerts Strong In Vitro and In Vivo Anti-Tumorigenic Activity in Kirsten Rat Sarcoma-Mutated Cancers

The Kirsten rat sarcoma viral oncogene (KRAS) is one of the most well-known proto-oncogenes, frequently mutated in pancreatic and colorectal cancers, among others. We hypothesized that the intracellular delivery of anti-KRAS antibodies (KRAS-Ab) with biodegradable polymeric micelles (PM) would block the overactivation of the KRAS-associated cascades and revert the effect of its mutation. To this end, PM-containing KRAS-Ab (PM-KRAS) were obtained using Pluronic F127. The feasibility of using PM for antibody encapsulation as well as the conformational change of the polymer and its intermolecular interactions with the antibodies was studied, for the first time, using in silico modeling. In vitro, encapsulation of KRAS-Ab allowed their intracellular delivery in different pancreatic and colorectal cancer cell lines. Interestingly, PM-KRAS promoted a high proliferation impairment in regular cultures of KRAS-mutated HCT116 and MIA PaCa-2 cells, whereas the effect was neglectable in non-mutated or KRAS-independent HCT-8 and PANC-1 cancer cells, respectively. Additionally, PM-KRAS induced a remarkable inhibition of the colony formation ability in low-attachment conditions in KRAS-mutated cells. In vivo, when compared with the vehicle, the intravenous administration of PM-KRAS significantly reduced tumor volume growth in HCT116 subcutaneous tumor-bearing mice. Analysis of the KRAS-mediated cascade in cell cultures and tumor samples showed that the effect of PM-KRAS was mediated by a significant reduction of the ERK phosphorylation and a decrease in expression in the stemness-related genes. Altogether, these results unprecedently demonstrate that the delivery of KRAS-Ab mediated by PM can safely and effectively reduce the tumorigenicity and the stemness properties of KRAS-dependent cells, thus bringing up new possibilities to reach undruggable intracellular targets.

Targeting Cancer Stem Cells as the Key Driver of Carcinogenesis and Therapeutic Resistance

The emerging concept of cancer stem cells (CSCs) as the key driver behind carcinogenesis, progression, and diversity has displaced the prior model of a tumor composed of cells with similar subsequently acquired mutations and an equivalent capacity for renewal, invasion, and metastasis. This significant change has shifted the research focus toward targeting CSCs to eradicate cancer. CSCs may be characterized using cell surface markers. They are defined by their capacity to self-renew and differentiate, resist conventional therapies, and generate new tumors following repeated transplantation in xenografted mice. CSCs' functional capabilities are governed by various intracellular and extracellular variables such as pluripotency-related transcription factors, internal signaling pathways, and external stimuli. Numerous natural compounds and synthetic chemicals have been investigated for their ability to disrupt these regulatory components and inhibit stemness and terminal differentiation in CSCs, hence achieving clinical implications. However, no cancer treatment focuses on the biological consequences of these drugs on CSCs, and their functions have been established. This article provides a biomedical discussion of cancer at the time along with an overview of CSCs and their origin, features, characterization, isolation techniques, signaling pathways, and novel targeted therapeutic approaches. Additionally, we highlighted the factors endorsed as controlling or helping to promote stemness in CSCs. Our objective was to encourage future studies on these prospective treatments to develop a framework for their application as single or combined therapeutics to eradicate various forms of cancer.

Polymeric micelles and cancer therapy: an ingenious multimodal tumor-targeted drug delivery system

Since the beginning of pharmaceutical research, drug delivery methods have been an integral part of it. Polymeric micelles (PMs) have emerged as multifunctional nanoparticles in the current technological era of nanocarriers, and they have shown promise in a range of scientific fields. They can alter the release profile of integrated pharmacological substances and concentrate them in the target zone due to their improved permeability and retention, making them more suitable for poorly soluble medicines. With their ability to deliver poorly soluble chemotherapeutic drugs, PMs have garnered considerable interest in cancer. As a result of their remarkable biocompatibility, improved permeability, and minimal toxicity to healthy cells, while also their capacity to solubilize a wide range of drugs in their micellar core, PMs are expected to be a successful treatment option for cancer therapy in the future. Their nano-size enables them to accumulate in the tumor microenvironment (TME) via the enhanced permeability and retention (EPR) effect. In this review, our major aim is to focus primarily on the stellar applications of PMs in the field of cancer therapeutics along with its mechanism of action and its latest advancements in drug and gene delivery (DNA/siRNA) for cancer, using various therapeutic strategies such as crossing blood-brain barrier, gene therapy, photothermal therapy (PTT), and immunotherapy. Furthermore, PMs can be employed as "smart drug carriers," allowing them to target specific cancer sites using a variety of stimuli (endogenous and exogenous), which improve the specificity and efficacy of micelle-based targeted drug delivery. All the many types of stimulants, as well as how the complex of PM and various anticancer drugs react to it, and their pharmacodynamics are also reviewed here. In conclusion, commercializing engineered micelle nanoparticles (MNPs) for application in therapy and imaging can be considered as a potential approach to improve the therapeutic index of anticancer drugs. Furthermore, PM has stimulated intense interest in research and clinical practice, and in light of this, we have also highlighted a few PMs that have previously been approved for therapeutic use, while the majority are still being studied in clinical trials for various cancer therapies.

Vav1 Selectively Down-Regulates Akt2 through miR-29b in Certain Breast Tumors with Triple Negative Phenotype

Triple negative breast cancer (TNBC) represents the most aggressive breast tumor, showing a high intrinsic variability in terms of both histopathological features and response to therapies. Blocking the Akt signaling pathway is a well-studied approach in the treatment of aggressive breast tumors. The high homology among the Akt isoforms and their distinct, and possibly opposite, oncogenic functions made it difficult to develop effective drugs. Here we investigated the role of Vav1 as a potential down-regulator of individual Akt isozymes. We revealed that the over-expression of Vav1 in triple negative MDA-MB-231 cells reduced only the Akt2 isoform, acting at the post-transcriptional level through the up-modulation of miR-29b. The Vav1/miR-29b dependent decrease in Akt2 was correlated with a reduced lung colonization of circulating MDA-MB-231 cells. In cell lines established from PDX, the Vav1 induced down-modulation of Akt2 is strongly dependent on miR-29b and occurs only in some TNBC tumors. These findings may contribute to better classify breast tumors having the triple negative phenotype, and suggest that the activation of the Vav1/miR-29b axis, precisely regulating the amount of an Akt isozyme crucial for tumor dissemination, could have great potential for driving more accurate therapies to TNBCs, often not eligible or resistant to treatments.

Colorectal cancer inhibition by BET inhibitor JQ1 is MYC-independent and not improved by nanoencapsulation

Bromodomain and extraterminal domain protein inhibitors (BETi) for cancer treatment did not convince during their first clinical trials. Their epigenetic mechanism of action is still not well understood, even if MYC is generally considered as its main downstream target. In this context, we intended to assess two new nanoformulations of the BETi JQ1 for the treatment of colorectal cancer (CRC). JQ1 was encapsulated at 10 mg/mL in lipid nanocapsules (LNC) or polymeric micelles (PM), both compatible for an intravenous administration. Their effect was compared with free JQ1 on several CRC cell lines in vitro and with daily intraperitoneal cyclodextrin (CD)-loaded JQ1 on the CT26 CRC tumor model in vivo. We showed that LNC preferentially accumulated in tumor, liver, and lymph nodes. LNC-JQ1 and CD-JQ1 similarly delayed tumor growth and increased median survival from 15 to 23 or 20.5 days. JQ1 altered MYC in only two among four CRC cell lines. This MYC-independence found in CT26 was confirmed in vivo by PCR and immunohistochemistry. The main explanation of the JQ1 anticancer effect was an increase in apoptosis. The investigation of its impact on the tumor microenvironment did not show significant effects. Finally, JQ1 association with irinotecan did not synergize in vivo with JQ1 nanoformulations. In conclusion, we demonstrated that the JQ1 anticancer effect was not improved by nanoencapsulation even if their tumor delivery was probably higher. MYC inhibition was not associated to JQ1 efficacy in the case of the CT26 CRC murine model.

RNA-Based Therapeutics: Current Developments in Targeted Molecular Therapy of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a highly heterogeneous and aggressive cancer that has the highest mortality rate out of all breast cancer subtypes. Conventional clinical treatments targeting ER, PR, and HER2 receptors have been unsuccessful in the treatment of TNBC, which has led to various research efforts in developing new strategies to treat TNBC. Targeted molecular therapy of TNBC utilizes knowledge of key molecular signatures of TNBC that can be effectively modulated to produce a positive therapeutic response. Correspondingly, RNA-based therapeutics represent a novel tool in oncology with their ability to alter intrinsic cancer pathways that contribute to poor patient prognosis. Current RNA-based therapeutics exist as two major areas of investigation-RNA interference (RNAi) and RNA nanotherapy, where RNAi utilizes principles of gene silencing, and RNA nanotherapy utilizes RNA-derived nanoparticles to deliver chemotherapeutics to target cells. RNAi can be further classified as therapeutics utilizing either small interfering RNA (siRNA) or microRNA (miRNA). As the broader field of gene therapy has advanced significantly in recent years, so too have efforts in the development of effective RNA-based therapeutic strategies for treating aggressive cancers, including TNBC. This review will summarize key advances in targeted molecular therapy of TNBC, describing current trends in treatment using RNAi, combination therapies, and recent efforts in RNA immunotherapy, utilizing messenger RNA (mRNA) in the development of cancer vaccines.

Au-Fe3O4 nanoagent coated cell membrane for targeted delivery and enhanced chem/photo therapy

Here, we propose a cancer cell membrane (CM) coated Au-Fe₃O₄ complex (AFTP@CM), loaded with tannic acid and phorbol 12-myristate 13-acetate for targeted drug delivery and enhanced chem/photo therapy.

Redox responsive Pluronic micelle mediated delivery of functional siRNA: a modular nano-assembly for targeted delivery

There is an unmet need to develop strategies that allow site-specific delivery of short interfering RNA (siRNA) without any associated toxicity. To address this challenge, we have developed a novel siRNA delivery platform using chemically modified pluronic F108 as an amphiphilic polymer with a releasable bioactive disulfide functionality. The micelles exhibited thermoresponsive properties and showed a hydrodynamic size of ∼291 nm in DLS and ∼200-250 nm in SEM at 37 °C. The grafting of free disulfide pyridyl groups enhanced the transfection efficiency and was successfully demonstrated in human colon carcinoma (HCT116; 88%) and glioma cell lines (U87; 90%), non-cancerous human dermal fibroblast (HDF; 90%) cells as well as in mouse embryonic stem (mES; 54%) cells. To demonstrate the versatility of our modular nanocarrier design, we conjugated the MDGI receptor targeting COOP peptide on the particle surface that allowed the targeted delivery of the cargo molecules to human patent-derived primary BT-13 gliospheres. Transfection experiments with this design resulted in ∼65% silencing of STAT3 mRNA in BT-13 gliospheres, while only ∼20% of gene silencing was observed in the absence of the peptide. We believe that our delivery method solves current problems related to the targeted delivery of RNAi drugs for potential in vivo applications.

Lysosomal escaped protein nanocarriers for nuclear-targeted siRNA delivery

In the process of drug carrier design, lysosome degradation in cells is often neglected, which makes a considerable number of drugs not play a role. Here, we have constructed a tumor treatment platform (Apn/siRNA/NLS/HA/Apt) with unique lysosomal escape function and excellent cancer treatment effect. Apoferritin (Apn) has attracted more and more attention because of its high uniformity, modifiability, and controllability. Meanwhile, its endogenous nature can avoid the risk of immune response being eliminated. We used aptamer modified iron deficient protein nanocages (Apn) to tightly encapsulate the combination of siRNA and NLS (siRNA/NLS) with influenza virus hemagglutinin (HA peptide). After Apn/siRNA/NLS/HA/Apt was targeted into cells, the acidic environment of lysosome led to the cleavage of Apn nanocages, and the release of siRNA/NLS and HA peptide. HA peptide can destroy lysosome membrane, make siRNA/NLS escape lysosome, and enter the nucleus under the action of NLS, resulting in efficient gene silencing effect. This kind of cancer treatment strategy based on Apn nanocage shows high biocompatibility and unique lysosome escape property, which significantly improves the drug delivery and treatment efficiency. Lysosomal escape protein nanocarriers for nuclear-targeted siRNA delivery.

Perspectives of nano-carrier drug delivery systems to overcome cancer drug resistance in the clinics

Advanced cancer is still considered an incurable disease because of its metastatic spread to distal organs and progressive gain of chemoresistance. Even though considerable treatment progress and more effective therapies have been achieved over the past years, recurrence in the long-term and undesired side effects are still the main drawbacks of current clinical protocols. Moreover, a majority of chemotherapeutic drugs are highly hydrophobic and need to be diluted in organic solvents, which cause high toxicity, in order to reach effective therapeutic dose. These limitations of conventional cancer therapies prompted the use of nanomedicine, the medical application of nanotechnology, to provide more effective and safer cancer treatment. Potential of nanomedicines to overcome resistance, ameliorate solubility, improve pharmacological profile, and reduce adverse effects of chemotherapeutical drugs is thus highly regarded. Their use in the clinical setting has increased over the last decade. Among the various existing nanosystems, nanoparticles have the ability to transform conventional medicine by reducing the adverse effects and providing a controlled release of therapeutic agents. Also, their small size facilitates the intracellular uptake. Here, we provide a closer review of clinical prospects and mechanisms of action of nanomedicines to overcome drug resistance. The significance of specific targeting towards cancer cells is debated as well.

Nanosized Drug Delivery Systems for Breast Cancer Stem Cell Targeting

Breast cancer stem cells (BCSCs), also known as breast cancer initiating cells, are reported to be responsible for the initiation, progression, therapeutic resistance, and relapse of breast cancer. Conventional therapeutic agents mainly kill the bulk of breast tumor cells and fail to eliminate BCSCs, even enhancing the fraction of BCSCs in breast tumors sometimes. Therefore, it is essential to develop specific and effective methods of eliminating BCSCs that will enhance the efficacy of killing breast tumor cells and thereby, increase the survival rates and quality of life of breast cancer patients. Despite the availability of an increasing number of anti-BCSC agents, their clinical translations are hindered by many issues, such as instability, low bioavailability, and off-target effects. Nanosized drug delivery systems (NDDSs) have the potential to overcome the drawbacks of anti-BCSC agents by providing site-specific delivery and enhancing of the stability and bioavailability of the delivered agents. In this review, we first briefly introduce the strategies and agents used against BCSCs and then highlight the mechanism of action and therapeutic efficacy of several state-of-the-art NDDSs that can be used to treat breast cancer by eliminating BCSCs.

Recent advances in drug delivery systems for targeting cancer stem cells

Cancer stem cells (CSCs) are a subpopulation of cancer cells with functions similar to those of normal stem cells. Although few in number, they are capable of self-renewal, unlimited proliferation, and multi-directional differentiation potential. In addition, CSCs have the ability to escape immune surveillance. Thus, they play an important role in the occurrence and development of tumors, and they are closely related to tumor invasion, metastasis, drug resistance, and recurrence after treatment. Therefore, specific targeting of CSCs may improve the efficiency of cancer therapy. A series of corresponding promising therapeutic strategies based on CSC targeting, such as the targeting of CSC niche, CSC signaling pathways, and CSC mitochondria, are currently under development. Given the rapid progression in this field and nanotechnology, drug delivery systems (DDSs) for CSC targeting are increasingly being developed. In this review, we summarize the advances in CSC-targeted DDSs. Furthermore, we highlight the latest developmental trends through the main line of CSC occurrence and development process; some considerations about the rationale, advantages, and limitations of different DDSs for CSC-targeted therapies were discussed.

Pluronic-based nanovehicles: Recent advances in anticancer therapeutic applications

Pluronics are a class of amphiphilic tri-block copolymers with wide pharmaceutical applicability. In the past decades, the ability to form biocompatible nanosized micelles was exploited to formulate stable drug nanovehicles with potential use in antitumor therapy. Due to the great potential for tuning physical and structural properties of Pluronic unimers, a panoply of drug or polynucleotide-loaded micelles was prepared and tested for their antitumoral activity. The attractive inherent antitumor properties of Pluronic polymers in combination with cell targeting and stimuli-responsive ligands greatly improved antitumoral therapeutic effects of tested drugs. In spite of that, the extraordinary complexity of biological challenges in the delivery of micellar drug payload makes their therapeutic potential still not exploited to the fullest. In this review paper we attempt to present the latest developments in the field of Pluronic based nanovehicles and their application in anticancer therapy with an overview of the chemistry involved in the preparation of these nanovehicles.

Simvastatin-loaded polymeric micelles are more effective and less toxic than conventional statins in a pre-clinical model of advanced chronic liver disease

Chronic liver disease (CLD) has no effective treatments apart from reducing its complications. Simvastatin has been tested as vasoprotective drug in experimental models of CLD showing promising results, but also limiting adverse effects. Two types of Pluronic® carriers loading simvastatin (PM108-simv and PM127-simv) as a drug delivery system were developed to avoid these toxicities while increasing the therapeutic window of simvastatin. PM127-simv showed the highest rates of cell internalization in rat liver sinusoidal endothelial cells (LSECs) and significantly lower toxicity than free simvastatin, improving cell phenotype. The in vivo biodistribution was mainly hepatic with 50% of the injected PM found in the liver. Remarkably, after one week of administration in a model of CLD, PM127-simv demonstrated superior effect than free simvastatin in reducing portal hypertension. Moreover, no signs of toxicity of PM127-simv were detected. Our results indicate that simvastatin targeted delivery to LSEC is a promising therapeutic approach for CLD.

Intracellular Delivery of Anti-SMC2 Antibodies against Cancer Stem Cells

Structural maintenance of chromosomes protein 2 (SMC2) is a central component of the condensin complex involved in DNA supercoiling, an essential process for embryonic stem cell survival. SMC2 over-expression has been related with tumorigenesis and cancer malignancy and its inhibition is regarded as a potential therapeutic strategy even though no drugs are currently available. Here, we propose to inhibit SMC2 by intracellular delivery of specific antibodies against the SMC2 protein. This strategy aims to reduce cancer malignancy by targeting cancer stem cells (CSC), the tumoral subpopulation responsible of tumor recurrence and metastasis. In order to prevent degradation and improve cellular internalization, anti-SMC2 antibodies (Ab-SMC2) were delivered by polymeric micelles (PM) based on Pluronic^® F127 amphiphilic polymers. Importantly, scaffolding the Ab-SMC2 onto nanoparticles allowed its cellular internalization and highly increased its efficacy in terms of cytotoxicity and inhibition of tumorsphere formation in MDA-MB-231 and HCT116 breast and colon cancer cell lines, respectively. Moreover, in the case of the HCT116 cell line G1, cell-cycle arrest was also observed. In contrast, no effects from free Ab-SMC2 were detected in any case. Further, combination therapy of anti-SMC2 micelles with paclitaxel (PTX) and 5-Fluorouracil (5-FU) was also explored. For this, PTX and 5-FU were respectively loaded into an anti-SMC2 decorated PM. The efficacy of both encapsulated drugs was higher than their free forms in both the HCT116 and MDA-MB-231 cell lines. Remarkably, micelles loaded with Ab-SMC2 and PTX showed the highest efficacy in terms of inhibition of tumorsphere formation in HCT116 cells. Accordingly, our data clearly suggest an effective intracellular release of antibodies targeting SMC2 in these cell models and, further, strong cytotoxicity against CSC, alone and in combined treatments with Standard-of-Care drugs.

Insights into new mechanisms and models of cancer stem cell multidrug resistance

The acquisition of genetic alterations, clonal evolution, and the tumor microenvironment promote cancer progression, metastasis and therapy resistance. These events correspond to the establishment of the great phenotypic heterogeneity and plasticity of cancer cells that contribute to tumor progression and resistant disease. Targeting resistant cancers is a major challenge in oncology; however, the underlying processes are not yet fully understood. Even though current treatments can reduce tumor size and increase life expectancy, relapse and multidrug resistance (MDR) ultimately remain the second cause of death in developed countries. Recent evidence points toward stem-like phenotypes in cancer cells, promoted by cancer stem cells (CSCs), as the main culprit of cancer relapse, resistance (radiotherapy, hormone therapy, and/or chemotherapy) and metastasis. Many mechanisms have been proposed for CSC resistance, such as drug efflux through ABC transporters, overactivation of the DNA damage response (DDR), apoptosis evasion, prosurvival pathways activation, cell cycle promotion and/or cell metabolic alterations. Nonetheless, targeted therapy toward these specific CSC mechanisms is only partially effective to prevent or abolish resistance, suggesting underlying additional causes for CSC resilience. This article aims to provide an integrated picture of the MDR mechanisms that operate in CSCs' behavior and to propose a novel model of tumor evolution during chemotherapy. Targeting the pathways mentioned here might hold promise and reveal new strategies for future clinical therapeutic approaches.

ENS, Boer JC, Ferji K, Six JL, Chen X, Elkord E, Plebanski M, Mohamud R. Synergistic Effects of Nanomedicine Targeting TNFR2 and DNA Demethylation Inhibitor-An Opportunity for Cancer Treatment

Tumor necrosis factor receptor 2 (TNFR2) is expressed on some tumor cells, such as myeloma, Hodgkin lymphoma, colon cancer and ovarian cancer, as well as immunosuppressive cells. There is increasingly evidence that TNFR2 expression in cancer microenvironment has significant implications in cancer progression, metastasis and immune evasion. Although nanomedicine has been extensively studied as a carrier of cancer immunotherapeutic agents, no study to date has investigated TNFR2-targeting nanomedicine in cancer treatment. From an epigenetic perspective, previous studies indicate that DNA demethylation might be responsible for high expressions of TNFR2 in cancer models. This perspective review discusses a novel therapeutic strategy based on nanomedicine that has the capacity to target TNFR2 along with inhibition of DNA demethylation. This approach may maximize the anti-cancer potential of nanomedicine-based immunotherapy and, consequently, markedly improve the outcomes of the management of patients with malignancy.

Spatiotemporally controllable diphtheria toxin expression using a light-switchable transgene system combining multifunctional nanoparticle delivery system for targeted melanoma therapy

Gene therapy with external gene insertion (e. g. a suicide gene) and expression specifically in mutated tumor cells has shown to be a promising strategy in treatment of tumors. However, current tumor gene therapy often suffered from low efficiency in gene expression and off-target effects which may cause damage to normal tissues. To address these issues, in this study, a light-switchable transgene nanoparticle delivery system loaded with a diphtheria toxin A (DTA) segment encoded gene, a suicide gene for tumor cells, was developed. The nanoparticles contained vitamin E succinate-grafted polyethyleneimine core and arginylglycylaspartic acid (RGD)-modified pegylated hyaluronic acid shell for targeted delivery of the loaded gene to tumor cells via receptor-mediated (CD44 and αvβ3) endocytosis. Notably, the expression of target proteins in tumor cells could be conveniently regulated by adjusting the blue light intensity in the Light-On system. In in-vitro studies in cultured B16-F10 cells, the pG-DTA-loaded nano-micelles showed greatly improved inhibitory rate compared with the pG-DTA group. Moreover, in the tumor-bearing C57BL/6 mice model, the pG-DTA-loaded nanoparticle exhibited greatly improved efficacy and reduced systemic toxicity with significantly increased survival rate after 21 days. Significantly suppressed tumor angiogenesis was also identified in the nanoparticle-treated group likely due to the targeting ability of the RGD-modified nanoparticle. All the above results indicated that the combination of a light-switchable transgene system with a nanoparticle-based targeted delivery system have great potentials in gene therapy of malignant tumors with improved precision and efficacy.

Zileuton™ loaded in polymer micelles effectively reduce breast cancer circulating tumor cells and intratumoral cancer stem cells

Tumor recurrence, metastatic spread and progressive gain of chemo-resistance of advanced cancers are sustained by the presence of cancer stem cells (CSCs) within the tumor. Targeted therapies with the aim to eradicate these cells are thus highly regarded. However, often the use of new anti-cancer therapies is hampered by pharmacokinetic demands. Drug delivery through nanoparticles has great potential to increase efficacy and reduce toxicity and adverse effects. However, its production has to be based on intelligent design. Likewise, we developed polymeric nanoparticles loaded with Zileuton™, a potent inhibitor of cancer stem cells (CSCs), which was chosen based on high throughput screening. Its great potential for CSCs treatment was subsequently demonstrated in in vitro and in in vivo CSC fluorescent models. Encapsulated Zileuton™ reduces amount of CSCs within the tumor and effectively blocks the circulating tumor cells (CTCs) in the blood stream and metastatic spread.

Optimization of peptide-plasmid DNA vectors formulation for gene delivery in cancer therapy exploring design of experiments

The field of gene therapy still attracts great interest due to its potential therapeutic effect towards the most deadly diseases, such as cancer. For cancer gene therapy to be feasible and viable in a clinical setting, the design and development of a suitable gene delivery system is imperative. Peptide based vectors, in particular, reveal to be promising for therapeutic gene release. Following this, two different peptides, RALA and WRAP5, have been investigated mainly regarding their ability to form complexes with a p53 encoding plasmid (pDNA) with suitable properties for gene delivery. To address this issue, and after an initial screening study focused on the dependence of pDNA complexation capacity with the nitrogen to phosphate groups (N/P) ratio, a design of experiments (DoE) tool has been employed. For each peptide/pDNA system, parameters such as, the buffer pH and the N/P ratio were considered the DoE inputs and the vector size, zeta potential and pDNA complexation capacity (CC) were monitored as DoE outputs. The main goal was to find the optimal experimental conditions to minimize particle sizes, as well as, to maximize the positive surface charges of the formulated nanosystems and maximize the pDNA CC. Through the DoE method applied, the optimal RALA/pDNA and WRAP5/pDNA formulations were revealed and show interesting features related to peptide structure and pDNA complexation ability. This work illustrates the great utility of experimental design tools in optimizing the formulation of peptide/pDNA vectors in a minimum number of experiments providing relevant knowledge for the development of more suitable and efficient gene delivery systems. The new insights achieved on these carriers clearly instigate deeper research on gene therapy.

Pivotal Role of AKT2 during Dynamic Phenotypic Change of Breast Cancer Stem Cells

Therapeutic resistance seen in aggressive forms of breast cancer remains challenging for current treatments. More than half of the patients suffer from a disease relapse, most of them with distant metastases. Cancer maintenance, resistance to therapy, and metastatic disease seem to be sustained by the presence of cancer stem cells (CSC) within a tumor. The difficulty in targeting this subpopulation derives from their dynamic interconversion process, where CSC can differentiate to non-CSC, which in turn de-differentiate into cells with CSC properties. Using fluorescent CSC models driven by the expression of ALDH1A 1(aldehyde dehydrogenase 1A1), we confirmed this dynamic phenotypic change in MDA-MB-231 breast cancer cells and to identify Serine/Threonine Kinase 2 (AKT2) as an important player in the process. To confirm the central role of AKT2, we silenced AKT2 expression via small interfering RNA and using a chemical inhibitor (CCT128930), in both CSC and non-CSC from different cancer cell lines. Our results revealed that AKT2 inhibition effectively prevents non-CSC reversion through mesenchymal to epithelial transition, reducing invasion and colony formation ability of both, non-CSC and CSC. Further, AKT2 inhibition reduced CSC survival in low attachment conditions. Interestingly, in orthotopic tumor mouse models, high expression levels of AKT2 were detected in circulating tumor cells (CTC). These findings suggest AKT2 as a promising target for future anti-cancer therapies at three important levels: (i) Epithelial-to-mesenchymal transition (EMT) reversion and maintenance of CSC subpopulation in primary tumors, (ii) reduction of CTC and the likelihood of metastatic spread, and (iii) prevention of tumor recurrence through inhibition of CSC tumorigenic and metastatic potential.

Cyclin-dependent kinase 9 promotes cervical cancer development via AKT2/p53 pathway

Aberrant activation of cyclin-dependent kinase 9 (CDK9) is widespread in human cancers. However, the underlying mechanisms of CDK9 activation and the therapeutic potential of CDK9 inhibition in cervical cancer remain largely unknown. Here, we report that CDK9 is gradually upregulated during cervical lesion progression and regulated by HPV16 E6. CDK9 levels are highly correlated with FIGO stage, pathological grade, deep-stromal invasion, tumor size, and lymph nodes metastasis. Knockdown of CDK9 by specific siRNA inhibits cervical cancer cell proliferation in vitro, as well as tumorigenesis in vivo. CDK9 inhibition causes a significant decreased AKT2 and increased p53 protein expression revealing novel CDK9-regulatory mechanisms. Overexpression of AKT2 rescued the suppressive effects caused by CDK9 knockdown, suggesting that AKT2 induction is essential for CDK9-induced transformation. Moreover, CDK9 expression was positively correlated with AKT2 and negatively correlated with p53 in cervical cancer tissues with HPV16 infection. Our findings demonstrate for the first time that CDK9 acts as a proto-oncogene in cervical cancer, modulating cell proliferation and apoptosis through AKT2/p53 pathway. Therefore, our data provide novel mechanistic insights into the role of CDK9 in cervical cancer development. © 2018 IUBMB Life, 71(3):347-356, 2019.

Dynamism, Sensitivity, and Consequences of Mesenchymal and Stem-Like Phenotype of Cancer Cells

There are remarkable similarities in the description of cancer stem cells (CSCs) and cancer cells with mesenchymal phenotype. Both cell types are highly tumorigenic, resistant against common anticancer treatment, and thought to cause metastatic growth. Moreover, cancer cells are able to switch between CSC and non-CSC phenotypes and vice versa, to ensure the necessary balance within the tumor. Likewise, cancer cells can switch between epithelial and mesenchymal phenotypes via well-described transition (EMT/MET) that is thought to be crucial for tumor propagation. In this review, we discuss whether, and to which extend, the CSCs and mesenchymal cancer cells are overlapping phenomena in terms of mechanisms, origin, and implication for cancer treatment. As well, we describe the dynamism of both phenotypes and involvement of the tumor microenvironment in CSC reversion and in EMT.

S. Rational Design of a siRNA Delivery System: ALOX5 and Cancer Stem Cells as Therapeutic Targets

The search for an ideal gene delivery system is a long and laborious process in which several factors from the first idea to final formulation, including main challenges, peaks and troughs, should be deeply taken into consideration to ensure adequate biological safety and in vivo efficacy endpoints. Arachidonate 5-lipoxygenase (ALOX5), a crucial player related with cancer development and in particular with cancer stem cells malignancy. In this work we describe the process behind the development of a small interfering RNA (siRNA) delivery system to inhibit ALOX5 in cancer stem cells (CSC), as a model target gene. We started by screening chitosan polyplexes, among different types of chitosan in different complexation conditions. Due to the low silencing efficacy obtained, chitosan polyplexes were combined with Pluronic®-based polymeric micelles with recognized advantages regarding gene transfection. We tested different types of polymeric particles to improve the biological efficacy of chitosan polyplexes. Nevertheless, limited transfection efficiency was still detected. The well-established polyethyleneimine (PEI) cationic polymer was used in substitution of chitosan, in combination with polymeric micelles, originating PEI-siRNA-Pluronic® systems. The presence of Pluronic® F127 in the formulation showed to be of utmost importance because not only the silencing activity of the polyplexes was improved, but also PEI-associated toxicity was clearly reduced. This, allowed to increase the amount of PEI inside the system and its overall efficacy. Indeed, different types of PEI, N/P ratios and preparation methods were tested until an optimal formulation composed by PEI 10k branched-based polyplexes at an N/P ratio of 50 combined with micelles of Pluronic® F127 was selected. This combined micelle presented adequate technological properties, safety profile, and biological efficacy, resulting in high ALOX5 gene silencing and strong reduction of invasion and transformation capabilities of a stem cell subpopulation isolated from MDA-MB-231 triple negative breast cancer cells.