Alendronate-functionalized porous nano-crystalsomes mitigate osteolysis and consequent inhibition of tumor growth in a tibia-induced metastasis model

Bone is one of the most prevalent sites of metastases in various epithelial malignancies, including breast cancer and this metastasis to bone often leads to severe skeletal complications in women due to its osteolytic nature. To address this, we devised a novel drug delivery approach using an Alendronate (ALN) functionalized self-assembled porous crystalsomes for concurrent targeting of Oleanolic acid (OA) and ALN (ALN + OA@NCs) to bone metastasis. Initially, the conjugation of both PEG-OA and OA-PEG-ALN with ALN and OA was achieved, and this conjugation was then self-assembled into porous crystalsomes (ALN + OA@NCs) by nanoemulsion crystallization. The reconstruction of a 3D single particle using transmission electron microscopy ensured the crystalline porous structure of ALN + OA@NCs, was well aligned with characteristic nanoparticle attributes including size distribution, polydispersity, and zeta potential. Further, ALN + OA@NCs showed enhanced efficacy in comparison to OA@NCs suggesting the cytotoxic roles of ALN towards cancer cells, followed by augmentation ROS generation (40.81%), mitochondrial membrane depolarization (57.20%), and induction of apoptosis (40.43%). We found that ALN + OA@NCs facilitated inhibiting osteoclastogenesis and bone resorption followed by inhibited osteolysis. In vivo activity of ALN + OA@NCs in the 4 T1 cell-induced tibia model rendered a reduced bone loss in the treated mice followed by restoring bone morphometric markers which were further corroborated bone-targeting effects of ALN + OA@NCs to reduce RANKL-stimulated osteoclastogenesis. Further, In vivo intravenous pharmacokinetics showed the improved therapeutic profile of the ALN + OA@NCs in comparison to the free drug, prolonging the levels of the drug in the systemic compartment by reducing the clearance culminating the higher accumulation at the tumor site. Our finding proposed that ALN + OA@NCs can effectively target and treat breast cancer metastasis to bone and its associated complications.

Extracellular vesicles-powered immunotherapy: Unleashing the potential for safer and more effective cancer treatment

Cancer treatment has seen significant advancements with the introduction of Onco-immunotherapies (OIMTs). Although some of these therapies have received approval for use, others are either undergoing testing or are still in the early stages of development. Challenges persist in making immunotherapy widely applicable to cancer treatment. To maximize the benefits of immunotherapy and minimize potential side effects, it's essential to improve response rates across different immunotherapy methods. A promising development in this area is the use of extracellular vesicles (EVs) as novel delivery systems. These small vesicles can effectively deliver immunotherapies, enhancing their effectiveness and reducing harmful side effects. This article discusses the importance of integrating nanomedicines into OIMTs, highlighting the challenges with current anti-OIMT methods. It also explores key considerations for designing nanomedicines tailored for OIMTs, aiming to improve upon existing immunotherapy techniques. Additionally, the article looks into innovative approaches like biomimicry and the use of natural biomaterial-based nanocarriers (NCs). These advancements have the potential to transform the delivery of immunotherapy. Lastly, the article addresses the challenges of moving OIMTs from theory to clinical practice, providing insights into the future of using advanced nanotechnology in cancer treatment.

Exploring nanocarriers as innovative materials for advanced drug delivery strategies in onco-immunotherapies

In recent years, Onco-immunotherapies (OIMTs) have been shown to be a potential therapy option for cancer. Several immunotherapies have received regulatory approval, while many others are now undergoing clinical testing or are in the early stages of development. Despite this progress, a large number of challenges to the broad use of immunotherapies to treat cancer persists. To make immunotherapy more useful as a treatment while reducing its potentially harmful side effects, we need to know more about how to improve response rates to different types of immunotherapies. Nanocarriers (NCs) have the potential to harness immunotherapies efficiently, enhance the efficiency of these treatments, and reduce the severe adverse reactions that are associated with them. This article discusses the necessity to incorporate nanomedicines in OIMTs and the challenges we confront with current anti-OIMT approaches. In addition, it examines the most important considerations for building nanomedicines for OIMT, which may improve upon current immunotherapy methods. Finally, it highlights the applications and future scenarios of using nanotechnology.

Carbosilane Dendritic Amphiphiles from Cholesterol or Vitamin E for Micelle Formation

Cationic dendritic amphiphiles were prepared through the linkage of interesting hydrophobic molecules such as cholesterol or vitamin E to the focal point of carbosilane dendrons. These new dendritic systems self-assembled in saline, producing micellar aggregates with hydrodynamic diameters ranging from 6.5 to 9.2 nm, and critical micelle concentrations of approximately 5 and 10 μM for second- and third-generation systems, respectively. The assemblies were able to encapsulate drugs of different charges (anionic, neutral, and cationic). Surprisingly, a 92% encapsulation efficiency for diclofenac was achieved in micelles prepared from second-generation dendrons. Toxicity measurements on peripheral blood mononuclear cells indicated different behavior depending on the generation, corresponding to the micellar regime. In contrast to the third-generation system, the second-generation system was non-toxic up to 20 μM, opening a window for its use in a micellar regimen, thereby operating as a drug delivery system for different biomedical applications.

High-nuclearity Luminescent Lanthanide Nanocages for Tumor Drug Delivery

There is an unmet need for easy-to-visualize drug carriers that can deliver therapeutic cargoes deep into solid tumors. Herein, we report the preparation of ultrasmall luminescent imine-based lanthanide nanocages, Eu60 and Tb60 (collectively Ln60 ), designed to encapsulate anticancer chemotherapeutics for tumor therapy. The as-prepared nanocages possess large cavities suitable for the encapsulation of doxorubicin (DOX), yielding DOX@Ln60 nanocages with diameters around 5 nm. DOX@Ln60 are efficiently internalized by breast cancer cells, allowing the cells to be visualized via the intrinsic luminescent property of Ln(III). Once internalized, the acidic intracellular microenvironment promotes imine bond cleavage and the release of the loaded DOX. DOX@Ln60 inhibits DNA replication and triggers tumor cell apoptosis. In a murine triple negative breast cancer (TNBC) model, DOX@Ln60 was found to inhibit tumor growth with negligible side effects on normal tissues. It proved more effective than various controls, including DOX and Ln60 . The present nanocages thus point the way to the development of precise nanomedicines for tumor imaging and therapy.

Surface-Modified Lyotropic Crystalline Nanoconstructs Bearing Doxorubicin and Buparvaquone Target Sigma Receptors through pH-Sensitive Charge Conversion to Improve Breast Cancer Therapy

In the current study, we aimed to develop lyotropic crystalline nanoconstructs (LCNs) based on poly(l-glutamic acid) (PLG) with a two-tier strategy. The first objective was to confer pH-responsive charge conversion properties to facilitate the delivery of both doxorubicin (DOX) and buparvaquone (BPQ) in combination (B + D@LCNs) to harness their synergistic effects. The second goal was to achieve targeted delivery to sigma receptors within the tumor tissues. To achieve this, we designed a pH-responsive charge conversion system using a polymer consisting of poly(ethylenimine), poly(l-lysine), and poly(l-glutamic acid) (PLG), which was then covalently coupled with methoxybenzamide (MBA) for potential sigma receptor targeting. The resulting B + D@LCNs were further modified by surface functionalization with PLG-MBA to confer both sigma receptor targeting and pH-responsive charge conversion properties. Our observations indicated that at physiological pH 7.4, P/B + D-MBA@LCNs exhibited a negative charge, while under acidic conditions (pH 5.5, characteristic of the tumor microenvironment), they acquired a positive charge. The particle size of P/B + D-MBA@LCNs was determined to be 168.23 ± 2.66 nm at pH 7.4 and 201.23 ± 1.46 nm at pH 5.5. The crystalline structure of the LCNs was confirmed through small-angle X-ray scattering (SAXS) diffraction patterns. Receptor-mediated endocytosis, facilitated by P/B + D-MBA@LCNs, was confirmed using confocal laser scanning microscopy and flow cytometry. The P/B + D-MBA@LCNs formulation demonstrated a higher rate of G2/M phase arrest (55.20%) compared to free B + D (37.50%) and induced mitochondrial depolarization (59.39%) to a greater extent than P/B + D@LCNs (45.66%). Pharmacokinetic analysis revealed significantly improved area under the curve (AUC) values for both DOX and BPQ when administered as P/B + D-MBA@LCNs, along with enhanced tumor localization. Tumor regression studies exhibited a substantial reduction in tumor size, with P/B + D-MBA@LCNs leading to 3.2- and 1.27-fold reductions compared to B + D and nontargeted P/B + D@LCNs groups, respectively. In summary, this two-tier strategy demonstrates substantial promise for the delivery of a drug combination through the prototype formulation. It offers a potential chemotherapeutic option by minimizing toxic effects on healthy cells while maximizing therapeutic efficacy.

Immobilized doxorubicin and ribociclib carbamate linkers encaged in surface modified cubosomes spatially target tumor reductive environment to enhance antitumor efficacy

In the present investigation, we have strategically synthesized Glutathione (GSH) stimuli-sensitive analogues using carbamate linkers (CL) of DOX (DOX-CL) and RB (RB-CL) which were then anchored to gold nanoparticles (Au-DOX-CL, Au-RB-CL) using mPEG as a spacer. It was observed that carbamate linkage (CL) with four carbon spacer is critical, to position the terminal thiol group, to access the carbamate group efficiently to achieve GSH-assisted release of DOX and RB in tumor-specific environment. When assessed for GSH reductase activity in MDA-MB 231 cell lines, Au-DOX-CL and Au-RB-CL showed nearly 4.18 and 3.13 fold higher GSH reductive activity as compared to the control group respectively. To achieve spatial tumor targeting with a high payload of DOX and RB, Au-DOX-CL and Au-RB-CL were encapsulated in the cell-penetrating peptide (CPP) modified liquid crystalline cubosomes i.e. CPP-Cu(Au@CL-DR). After internalization, the prototype nanocarriers release respective drugs at a precise GSH concentration inside the tumor tissues, amplifying drug concentration to a tune of five-fold. The drug concentrations remain within the therapeutic window for 72 h with a significant reduction of RB (7.8-fold) and DOX (6-fold) concentrations in vital organs, rendering reduced toxicity and improved survival. Overall, this constitutes a promising chemotherapeutic strategy against cancer and its potential application in the offing.

Surface modification strategies in translocating nano-vesicles across different barriers and the role of bio-vesicles in improving anticancer therapy

Nanovesicles and bio-vesicles (BVs) have emerged as promising tools to achieve targeted cancer therapy due to their ability to overcome many of the key challenges currently being faced with conventional chemotherapy. These challenges include the diverse and often complex pathophysiology involving the progression of cancer, as well as the various biological barriers that circumvent therapeutic molecules reaching their target site in optimum concentration. The scientific evidence suggests that surface-functionalized nanovesicles and BVs camouflaged nano-carriers (NCs) both can bypass the established biological barriers and facilitate fourth-generation targeting for the improved regimen of treatment. In this review, we intend to emphasize the role of surface-functionalized nanovesicles and BVs camouflaged NCs through various approaches that lead to an improved internalization to achieve improved and targeted oncotherapy. We have explored various strategies that have been employed to surface-functionalize and biologically modify these vesicles, including the use of biomolecule functionalized target ligands such as peptides, antibodies, and aptamers, as well as the targeting of specific receptors on cancer cells. Further, the utility of BVs, which are made from the membranes of cells such as mesenchymal stem cells (MSCs), white blood cells (WBCs), red blood cells (RBCs), platelets (PLTs) as well as cancer cells also been investigated. Lastly, we have discussed the translational challenges and limitations that these NCs can encounter and still need to be overcome in order to fully realize the potential of nanovesicles and BVs for targeted cancer therapy. The fundamental challenges that currently prevent successful cancer therapy and the necessity of novel delivery systems are in the offing.

Ratiometric codelivery of Paclitaxel and Baicalein loaded nanoemulsion for enhancement of breast cancer treatment

The most prevalent clinical option for treating cancer is combination chemotherapy. In combination therapy, assessment and optimization for obtaining a synergistic ratio could be obtained by various preclinical setups. Currently, in vitro optimization is used to get synergistic cytotoxicity while constructing combinations. Herein, we co-encapsulated Paclitaxel (PTX) and Baicalein (BCLN) with TPP-TPGS1000 containing nanoemulsion (TPP-TPGS1000-PTX-BCLN-NE) for breast cancer treatment. The assessment of cytotoxicity of PTX and BCLN at different molar weight ratios provided an optimized synergistic ratio (1:5). Quality by Design (QbD) approach was later applied for the optimization as well as characterization of nanoformulation for its droplet size, zeta potential and drug content. TPP-TPGS1000-PTX-BCLN-NE significantly enhanced cellular ROS, cell cycle arrest, and depolarization of mitochondrial membrane potential in the 4T1 breast cancer cell line compared to other treatments. In the syngeneic 4T1 BALB/c tumor model, TPP-TPGS1000-PTX-BCLN-NE outperformed other nanoformulation treatments. The pharmacokinetic, biodistribution and live imaging studies pivoted TPP-TPGS1000-PTX-BCLN-NE enhanced bioavailability and PTX accumulation at tumor site. Later, histology studies confirmed nanoemulsion non-toxicity, expressing new opportunities and potential to treat breast cancer. These results suggested that current nanoformulation can be a potential therapeutic approach to effectively address breast cancer therapy.

AKR1B1 inhibition using NARI-29-an Epalrestat analogue-alleviates Doxorubicin-induced cardiotoxicity via modulating Calcium/CaMKII/MuRF-1 axis

The clinical use of doxorubicin (Dox) is narrowed due to its carbonyl reduction to doxorubicinol (Doxol) implicating resistance and cardiotoxicity. Hence, in the present study we have evaluated the cardioprotective effect of AKR1B1 (or aldose reductase, AR) inhibitor NARI-29 (epalrestat (EPS) analogue) and its effect in the Dox-modulated calcium/CaMKII/MuRF1 axis. Initially, the breast cancer patient survival associated with AKR1B1 expression was calculated using Kaplan Meier-plotter (KM-plotter). Further, breast cancer, cardiomyoblast (H9c2), and macrophage (RAW 264.7) cell lines were used to establish the in vitro combination effect of NARI-29 and Dox. To develop the cardiotoxicity model, mice were given Dox 2.5 mg/kg (i.p.), biweekly. The effect of AKR1B1 inhibition using NARI-29 on molecular and cardiac functional changes was measured using echocardiography, fluorescence-imaging, ELISA, immunoblotting, flowcytometry, High-Performance Liquid Chromatography with Fluorescence Detection (HPLC-FD) and cytokine-bead array methods. The bioinformatics data suggested that a high expression of AKR1B1 is associated with significantly low survival of breast cancer patients undergoing chemotherapy; hence, it could be a target for chemo-sensitization and chemo-prevention. Further, in vitro studies showed that AKR1B1 inhibition with NARI-29 has increased the accumulation and sensitized Dox to breast cancer cell lines. However, treatment with NARI-29 has alleviated the Dox-induced toxicity to cardiomyocytes and decreased the secretion of inflammatory cytokines from RAW 264.7 cells. In vivo studies revealed that the NARI-29 (25 and 50 mg/kg) has prevented the functional, histological, biochemical, and molecular alterations induced by Dox treatment. Moreover, we have shown that NARI-29 has prevented the carbonyl reduction of Dox to Doxol in the mouse heart, which reduced the calcium overload, prevented phosphorylation of CaMKII, and reduced the expression of MuRF1 to protect from cardiac injury and apoptosis. Hence in conclusion, AKR1B1 inhibitor NARI-29 could be used as an adjuvant therapeutic agent with Dox to prevent cardiotoxicity and synergize anti-breast cancer activity.

Enhanced apoptosis and mitochondrial cell death by paclitaxel-loaded TPP-TPGS1000-functionalized nanoemulsion

Background: The present research was designed to develop a nanoemulsion (NE) of triphenylphosphine-D-α-tocopheryl-polyethylene glycol succinate (TPP-TPGS₁₀₀₀) and paclitaxel (PTX) to effectively deliver PTX to improve breast cancer therapy. Materials & methods: A quality-by-design approach was applied for optimization and in vitro and in vivo characterization were performed. Results: The TPP-TPGS₁₀₀₀-PTX-NE enhanced cellular uptake, mitochondrial membrane depolarization and G₂M cell cycle arrest compared with free-PTX treatment. In addition, pharmacokinetics, biodistribution and in vivo live imaging studies in tumor-bearing mice showed that TPP-TPGS₁₀₀₀-PTX-NE had superior performance compared with free-PTX treatment. Histological and survival investigations ascertained the nontoxicity of the nanoformulation, suggesting new opportunities and potential to treat breast cancer. Conclusion: TPP-TPGS₁₀₀₀-PTX-NE improved the efficacy of breast cancer treatment by enhancing its effectiveness and decreasing drug toxicity.

Synergistic delivery of Imatinib through multifunctional nano-crystalline capsules, in response to redox environment for improved breast cancer therapy

Chondroitin anchored crystalline nano-capsules bearing Imatinib (IMT), and simvastatin (SMV) was developed using Poly (L-lactic acid) (PLLA) by two-step method, i.e., firstly, by synthesizing chondroitin (CSA) anchored simvastatin (SMV) using cystamine as a spacer (SMV-SS-CSA) for disulfide triggered glutathione (GSH) sensitive release and secondly, by developing phenyl boronic ester grafted Pluronic F68 (PEPF) for H₂O₂ responsive release. By combining these conjugates, we have prepared crystalline nano-capsules (CNs) for preferential targeting of CD44 receptors. The developed CNs were spherical when characterized through SEM, TEM, and AFM for surface morphology, while changes in particle size and crystalline structure were confirmed through Quasi-Elastic light scattering (QELS) and Wide Angle X-ray Scattering (WAXS). The enhanced cellular uptake was noted in chondroitin-modified nano-capsules IMT/SMV-SS-CSA@CNs compared to unmodified nano-capsules IMT+SMV@CNs. IMT/SMV-SS-CSA@CNs displayed significantly higher G2/M phase arrest (76.9%) than unmodified nano-capsules. The prototype formulation (IMT/SMV-SS-CSA@CNs) showed an overall improved pharmacokinetic profile in terms of both half-life and AUC_0-α. When tested in the 4T1 subcutaneously injected tumor-bearing Balb/c mice model, the tumor growth inhibition rate of IMT/SMV-SS-CSA@CNs was significantly higher (91%) than the IMT+SMV combination. Overall, the findings suggest that the proposed dual responsive chondroitin-modified drug delivery could have a step forward in achieving spatial and temporal targeting at the tumor site.

Aldose reductase and cancer metabolism: The master regulator in the limelight

It is strongly established that metabolic reprogramming mediates the initiation, progression, and metastasis of a variety of cancers. However, there is no common biomarker identified to link the dysregulated metabolism and cancer progression. Recent studies strongly advise the involvement of aldose reductase (AR) in cancer metabolism. AR-mediated glucose metabolism creates a Warburg-like effect and an acidic tumour microenvironment in cancer cells. Moreover, AR overexpression is associated with the impairment of mitochondria and the accumulation of free fatty acids in cancer cells. Further, AR-mediated reduction of lipid aldehydes and chemotherapeutics are involved in the activation of factors promoting proliferation and chemo-resistance. In this review, we have delineated the possible mechanisms by which AR modulates cellular metabolism for cancer proliferation and survival. An in-depth understanding of cancer metabolism and the role of AR might lead to the use of AR inhibitors as metabolic modulating agents for the therapy of cancer.

Self-Assembled Redox-Sensitive Polymeric Nanostructures Facilitate the Intracellular Delivery of Paclitaxel for Improved Breast Cancer Therapy

A two-tier approach has been proposed for targeted and synergistic combination therapy against metastatic breast cancer. First, it comprises the development of a paclitaxel (PX)-loaded redox-sensitive self-assembled micellar system using betulinic acid-disulfide-d-α-tocopheryl poly(ethylene glycol) succinate (BA-Cys-T) through carbonyl diimidazole (CDI) coupling chemistry. Second, hyaluronic acid is anchored to TPGS (HA-Cys-T) chemically through a cystamine spacer to achieve CD44 receptor-mediated targeting. We have established that there is significant synergy between PX and BA with a combination index of 0.27 at a molar ratio of 1:5. An integrated system comprising both BA-Cys-T and HA-Cys-T (PX/BA-Cys-T-HA) exhibited significantly higher uptake than PX/BA-Cys-T, indicating preferential CD44-mediated uptake along with the rapid release of drugs in response to higher glutathione concentrations. Significantly higher apoptosis (42.89%) was observed with PX/BA-Cys-T-HA than those with BA-Cys-T (12.78%) and PX/BA-Cys-T (33.38%). In addition, PX/BA-Cys-T-HA showed remarkable enhancement in the cell cycle arrest, improved depolarization of the mitochondrial membrane potential, and induced excessive generation of ROS when tested in the MDA-MB-231 cell line. An in vivo administration of targeted micelles showed improved pharmacokinetic parameters and significant tumor growth inhibition in 4T1-induced tumor-bearing BALB/c mice. Overall, the study indicates a potential role of PX/BA-Cys-T-HA in achieving both temporal and spatial targeting against metastatic breast cancer.

Trans-(±)-Kusunokinin Binding to AKR1B1 Inhibits Oxidative Stress and Proteins Involved in Migration in Aggressive Breast Cancer

Synthetic trans-(±)-kusunokinin ((±)KU), a potential anticancer substance, was revealed to have an inhibitory effect on breast cancer. According to the computational modeling prediction, AKR1B1, an oxidative stress and cancer migration protein, could be a target protein of trans-(-)-kusunokinin. In this study, we determined the binding of (±)KU and AKR1B1 on triple-negative breast and non-serous ovarian cancers. We found that (±)KU exhibited a cytotoxic effect that was significantly stronger than zopolrestat (ZP) and epalrestat (EP) (known AKR1B1 inhibitors) on breast and ovarian cancer cells. (±)KU inhibited aldose reductase activity that was stronger than trans-(-)-arctiin ((-)AR) but weaker than ZP and EP. Interestingly, (±)KU stabilized AKR1B1 on SKOV3 and Hs578T cells after being heated at 60 and 75 °C, respectively. (±)KU decreased malondialdehyde (MDA), an oxidative stress marker, on Hs578T cells in a dose-dependent manner and the suppression was stronger than EP. Furthermore, (±)KU downregulated AKR1B1 and its downstream proteins, including PKC-δ, NF-κB, AKT, Nrf2, COX2, Twist2 and N-cadherin and up-regulated E-cadherin. (±)KU showed an inhibitory effect on AKR1B1 and its downstream proteins, similar to siRNA-AKR1B1. Interestingly, the combination of siRNA-AKR1B1 with EP or (±)KU showed a greater effect on the suppression of AKR1B1, N-cadherin, E-cadherin and NF-κB than single treatments. Taken together, we concluded that (±)KU-bound AKR1B1 leads to the attenuation of cellular oxidative stress, as well as the aggressiveness of breast cancer cell migration.

Moving toward a new horizon for the aldose reductase inhibitor epalrestat to treat drug-resistant cancer

Epalrestat (EPA) is a potent inhibitor of aldose reductases AKR1B1 and AKR1B10, used for decades in Japan for the treatment of diabetic peripheral neuropathy. This orally-active, brain-permeable small molecule, with a relatively rare and essential 2-thioxo-4-thiazolidinone motif, functions as a regulator intracellular carbonyl species. The repurposing of EPA for the treatment of pediatric rare diseases, brain disorders and cancer has been proposed. A detailed analysis of the mechanism of action, and the benefit of EPA to combat advanced malignancies is offered here. EPA has revealed marked anticancer activities, alone and in combination with cytotoxic chemotherapy and targeted therapeutics, in experimental models of liver, colon, and breast cancers. Through inhibition of AKR1B1 and/or AKR1B10 and blockade of the epithelial-mesenchymal transition, EPA largely enhances the sensitivity of cancer cells to drugs like doxorubicin and sorafenib. EPA has revealed a major anticancer effect in an experimental model of basal-like breast cancer and clinical trials have been developed in patients with triple-negative breast cancer. The repurposing of the drug to treat chemo-resistant solid tumors seems promising, but more studies are needed to define the best trajectory for the positioning of EPA in oncology.

Smart nanomaterials for cancer diagnosis and treatment

Innovations in nanomedicine has guided the improved outcomes for cancer diagnosis and therapy. However, frequent use of nanomaterials remains challenging due to specific limitations like non-targeted distribution causing low signal-to-noise ratio for diagnostics, complex fabrication, reduced-biocompatibility, decreased photostability, and systemic toxicity of nanomaterials within the body. Thus, better nanomaterial-systems with controlled physicochemical and biological properties, form the need of the hour. In this context, smart nanomaterials serve as promising solution, as they can be activated under specific exogenous or endogenous stimuli such as pH, temperature, enzymes, or a particular biological molecule. The properties of smart nanomaterials make them ideal candidates for various applications like biosensors, controlled drug release, and treatment of various diseases. Recently, smart nanomaterial-based cancer theranostic approaches have been developed, and they are displaying better selectivity and sensitivity with reduced side-effects in comparison to conventional methods. In cancer therapy, the smart nanomaterials-system only activates in response to tumor microenvironment (TME) and remains in deactivated state in normal cells, which further reduces the side-effects and systemic toxicities. Thus, the present review aims to describe the stimulus-based classification of smart nanomaterials, tumor microenvironment-responsive behaviour, and their up-to-date applications in cancer theranostics. Besides, present review addresses the development of various smart nanomaterials and their advantages for diagnosing and treating cancer. Here, we also discuss about the drug targeting and sustained drug release from nanocarriers, and different types of nanomaterials which have been engineered for this intent. Additionally, the present challenges and prospects of nanomaterials in effective cancer diagnosis and therapeutics have been discussed.

A two-pronged photodynamic nanodrug to prevent metastasis of basal-like breast cancer

A two-pronged concept combining photodynamic therapy (PDT) and epithelial-mesenchymal transition (EMT) blockade in a minimalist nanoplatform was proposed to combat basal-like breast cancer (BLBC) metastasis. Based on PDT-mediated tumor killing and epalrestat (Epa)-mediated EMT blockade, as-prepared Ce6/Epa nanoparticles prevented BLBC metastasis effectively in vivo, providing a very promising two-pronged strategy against BLBC metastasis.

Preparation and in vitro evaluation of amphiphilic paclitaxel small molecule prodrugs and enhancement of oral absorption

A series of novel amphiphilic paclitaxel (PTX) small molecule prodrugs, PTX-succinic anhydride-cystamine (PTX-Cys), PTX-dithiodipropionic anhydride (PTX-SS-COOH) and PTX-succinic anhydride-cystamine-valine (PTX-SS-Val) were designed, synthesized and evaluated against cancer cell lines. Compared with paclitaxel, these prodrugs contained water-soluble groups such as amino, carboxyl and amino acid, which improved the aqueous solubility of the prodrugs. More importantly, the valine was introduced in PTX-SS-Val molecule and made the molecule conform to the structural characteristics of intestinal oligopeptide transporter PEPT1 substrate. Thus the oral bioavailability of prodrug could be improved because of the mediation of PEPT1 transporter. These small molecule paclitaxel prodrugs could self-assemble into nanoparticles in aqueous solution, which effectively improved the solubility of paclitaxel, and had certain stability in pH 6.5, pH 7.4 buffer solutions and simulated gastrointestinal fluids. Some of these prodrugs, especially for PTX-Cys and PTX-SS-Val, exhibited nearly equal or slightly better anticancer activity when compared to paclitaxel. Further studies on PTX-Cys and PTX-SS-Val showed that both had good intestinal absorption in the rat single-pass intestinal perfusion (SPIP) experiments. Oral pharmacokinetic experiments showed that PTX-SS-Val could effectively improve the oral bioavailability of PTX.

Development of putrescine anchored nano-crystalsomes bearing doxorubicin and oleanolic acid: deciphering their role in inhibiting metastatic breast cancer

Angiogenesis driven tumor initiation and progression calls for a targeted therapy.

Recent advances in the redox-responsive drug delivery nanoplatforms: A chemical structure and physical property perspective

Poor water solubility, off-target toxicity, and small therapeutic window are among major obstacles for the development of drug products. Redox-responsive drug delivery nanoplatforms not only overcome the delivery and pharmacokinetic pitfalls observed in conventional drug delivery, but also leverage the site-specific delivery properties. Cleavable diselenide and disulfide bonds in the presence of elevated reactive oxygen species (ROS) and glutathione concentration are among widely used stimuli-responsive bonds to design nanocarriers. This review covers a wide range of redox-responsive chemical structures and their properties for designing nanoparticles aiming controlled loading, delivery, and release of hydrophobic anticancer drugs at tumor site.

Theranostic lyotropic liquid crystalline nanostructures for selective breast cancer imaging and therapy

Herein, we report the development of theranostic lyotropic liquid crystalline nanostructures (LCN's) loaded with unique MnO nanoparticles (MNPs) for selective cancer imaging and therapy. MNPs serves as a fluorescent agent as well as a source of manganese (Mn²⁺) and enables localized oxidative stress under the hallmarks of cancer (acidosis, high H₂O₂ level). In pursuit of synergistic amplification of Mn²⁺ antitumor activity, betulinic acid (BA) is loaded in LCN's. In this investigation, nano-architecture of LCN's phase interface is established via SAXS, Cryo-TEM and Cryo-FESEM. Intriguing in vitro studies showed that the LCN's triggered hydroxyl radical production and exhibited greater selective cytotoxicity in cancer cells, ensuring the safety of normal cells. Significant tumor ablation is realized by the 96.5 % of tumor growth inhibition index of LCN's as compared to control group. Key insights into on-site drug release, local anti-cancer response, and tumor location are gained through precise guidance of fluorescent MNPs. In addition, comprehensive assessment of the safety, pharmacokinetics and tumor distribution behavior of LCN's is performed in vivo or ex vivo. This work emphasizes the promise of modulating tumor microenvironment with smart endogenous stimuli sensitive nano systems to achieve advanced comprehensive cancer nano-theranostics without any external stimulus. STATEMENT OF SIGNIFICANCE: Effective diagnosis and treatment approaches with maximum anti-cancer activity and minimal side-effects are critical to ameliorate cancer therapy. Compared to radiation, photodynamic and photothermal therapy, the specific and selective activation of tumor microenvironmental endogenous stimuli for the logical generation of cytotoxic OH^· free radicals serves as an efficient therapeutic strategy for chemodynamic-cancer treatment. In this investigation, MnO nanoparticles fulfill two needs (fluorescence-based optical imaging and a source of Mn²⁺ based chemodynamic therapy) in one unit. This approach also ensures the safety of normal cells, as the toxic OH^· free radical activity is substantially suppressed under the mild alkaline/H₂O₂ conditions in normal cell microenvironment.

The AKR1B1 inhibitor epalrestat suppresses the progression of cervical cancer

Cervical cancer is the leading cause of cancer-related death among women worldwide. Identifying an effective treatment with fewer side effects is imperative, because all of the current treatments have unique disadvantages. Aldo-keto reductase family 1 member B1 (AKR1B1) is highly expressed in various cancers and is associated with tumor development, but has not been studied in cervical cancer. In the current study, we used CRISPR/Cas9 technology to establish a stable HeLa cell line with AKR1B1 knockout. In vitro, AKR1B1 knockout inhibited the proliferation, migration and invasion of HeLa cells, providing evidence that AKR1B1 is an innovative therapeutic target. Notably, the clinically used epalrestat, an inhibitor of aldose reductases, including AKR1B1, had the same effect as AKR1B1 knockout on HeLa cells. This result suggests that epalrestat could be used in the clinical treatment of cervical cancer, a prospect that undoubtedly requires further research. Moreover, aiming to determine the underlying regulatory mechanism of AKR1B1, we screened a series of differentially regulated genes (DEGs) by RNA sequencing and verified selected DEGs by quantitative RT-PCR. In addition, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of the DEGs revealed a correlation between AKR1B1 and cancer. In summary, epalrestat inhibits the progression of cervical cancer by inhibiting AKR1B1, and thus may be a new drug for the clinical treatment of cervical cancer.

Role of aldo-keto reductase family 1 member B1 (AKR1B1) in the cancer process and its therapeutic potential

The role of aldo‐keto reductase family 1 member B1 (AKR1B1) in cancer is not totally clear but growing evidence is suggesting to have a great impact on cancer progression. AKR1B1 could participate in a complicated network of signalling pathways, proteins and miRNAs such as mir‐21 mediating mechanisms like inflammatory responses, cell cycle, epithelial to mesenchymal transition, cell survival and apoptosis. AKR1B1 has been shown to be mostly overexpressed in cancer. This overexpression has been associated with inflammatory mediators including nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NFκB), cell cycle mediators such as cyclins and cyclin‐dependent kinases (CDKs), survival proteins and pathways like mammalian target of rapamycin (mTOR) and protein kinase B (PKB) or AKT, and other regulatory factors in response to reactive oxygen species (ROS) and prostaglandin synthesis. In addition, inhibition of AKR1B1 has been shown to mostly have anti‐cancer effects. Several studies have also suggested that AKR1B1 inhibition as an adjuvant therapy could render tumour cells more sensitive to anti‐cancer therapy or alleviate the adverse effects of therapy. AKR1B1 could also be considered as a potential cancer diagnostic biomarker since its promoter has shown high levels of methylation. Although pre‐clinical investigations on the role of AKR1B1 in cancer and the application of its inhibitors have shown promising results, the lack of clinical studies on AKR1B1 inhibitors has hampered the use of these drugs to treat cancer. Thus, there is a need to conduct more clinical studies on the application of AKR1B1 inhibitors as adjuvant therapy on different cancers.

Recent Advances of D-α-tocopherol Polyethylene Glycol 1000 Succinate Based Stimuli-responsive Nanomedicine for Cancer Treatment

D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) is a pharmaceutical excipient approved by Chinese NMPA and FDA of USA. It's widely applied as a multifunctional drug carrier for nanomedicine. The advantages of TPGS include P-glycoprotein (P-gp) inhibition, penetration promotion, apoptosis induction via mitochondrial-associated apoptotic pathways, multidrug resistant (MDR) reversion, metastasis inhibition and so on. TPGS-based drug delivery systems which are responding to external stimulus can combine the inhibitory functions of TPGS towards P-gp with the environmentally responsive controlled release property and thus exerts a synergistic anti-cancer effect, through increased intracellular drug concentration in tumors cells and well-controlled drug release behavior. In this review, TPGS-based nano-sized delivery systems responsive to different stimuli were summarized and discussed, including pH-responsive, redoxresponsive and multi-responsive systems in various formulations. The achievements, mechanisms and different characteristics of TPGS-based stimuli-responsive drug-delivery systems in tumor therapy were also outlined.

pH-sensitive small molecule nanodrug self-assembled from amphiphilic vitamin B6-E analogue conjugate for targeted synergistic cancer therapy

To promote the targeted cancer therapy, the pH-sensitive small molecule nanodrug self-assembled from amphiphilic vitamin B6-E analogue conjugate was successfully constructed. Herein, water-soluble vitamin B6 with pKa (5.6) was chemically conjugated to lipid-soluble vitamin E succinate (α-TOS), which showed selective cancer cell killing ability and this amphiphilic small molecule vitamin conjugate could self-assemble to be free nanoparticles (NPs) and doxorubicin-loaded NPs (α-TOS-B6-NPs-DOX). The small molecule nanodrugs could perform the following characteristic: (i) stability in the sodium dodecyl sulfonate (SDS) solution and long-term storage stability in PBS via surface negative charge; (ii) tumor accumulation by enhanced penetration and retention (EPR) effect; (iii) improved cellular internalization by means of vitamin B6 transporting membrane carrier (VTC); and (iv) facilitating endosomal escape and rapid drug release for synergistic toxicity to tumor cells via charge reversal and ester hydrolysis at intracellular pH and/or esterase. Moreover, α-TOS-B6-NPs-DOX exhibited long blood circulation stability and significant tumor accumulation and inhibition with the decreased side effects in vivo. Thus, the pH-sensitive small molecule nanodrug self-assembled from amphiphilic vitamin B6-E analogue conjugate could be the potential drug carriers in targeted synergistic cancer therapy.

Multifunctional hybrid nanoconstructs facilitate intracellular localization of doxorubicin and genistein to enhance apoptotic and anti-angiogenic efficacy in breast adenocarcinoma

The progressive development of tumors leading to angiogenesis marks the advancement of cancer which requires specific targeted treatment preferably with combination chemotherapy.

Hyaluronic acid hydrophilic surface rehabilitating curcumin nanocrystals for targeted breast cancer treatment with prolonged biodistribution

Due to its high therapeutic efficiency and low systemic toxicity, natural bioactive curcumin has attracted more and more attention as a potential antineoplastic drug.