Quercetin and doxorubicin co-delivery using mesoporous silica nanoparticles enhance the efficacy of gastric carcinoma chemotherapy

A pH/ROS dual-responsive system for effective chemoimmunotherapy against melanoma via remodeling tumor immune microenvironment

Chemotherapeutics can induce immunogenic cell death (ICD) in tumor cells, offering new possibilities for cancer therapy. However, the efficiency of the immune response generated is insufficient due to the inhibitory nature of the tumor microenvironment (TME). Here, we developed a pH/reactive oxygen species (ROS) dual-response system to enhance chemoimmunotherapy for melanoma. The system productively accumulated in tumors by specific binding of phenylboronic acid (PBA) to sialic acids (SA). The nanoparticles (NPs) rapidly swelled and released quercetin (QUE) and doxorubicin (DOX) upon the stimulation of tumor microenvironment (TME). The in vitro and in vivo results consistently demonstrated that the NPs improved anti-tumor efficacy and prolonged survival of mice, significantly enhancing the effects of the combination. Our study revealed DOX was an ICD inducer, stimulating immune responses and promoting maturation of dendritic cells (DCs). Additionally, QUE served as a TME regulator by inhibiting the cyclooxygenase-2 (COX2)-prostaglandin E2 (PGE2) axis, which influenced various immune cells, including increasing cytotoxic T cells (CLTs) infiltration, promoting M1 macrophage polarization, and reducing regulatory T cells (Tregs) infiltration. The combination synergistically facilitated chemoimmunotherapy efficacy by remodeling the immunosuppressive microenvironment. This work presents a promising strategy to increase anti-tumor efficiency of chemotherapeutic agents.

Natural compounds: Wnt pathway inhibitors with therapeutic potential in lung cancer

The Wnt/β-catenin pathway is abnormally activated in most lung cancer tissues and considered to be an accelerator of carcinogenesis and lung cancer progression, which is closely related to increased morbidity rates, malignant progression, and treatment resistance. Although targeting the canonical Wnt/β-catenin pathway shows significant potential for lung cancer therapy, it still faces challenges owing to its complexity, tumor heterogeneity and wide physiological activity. Therefore, it is necessary to elucidate the role of the abnormal activation of the Wnt/β-catenin pathway in lung cancer progression. Moreover, Wnt inhibitors used in lung cancer clinical trials are expected to break existing therapeutic patterns, although their adverse effects limit the treatment window. This is the first study to summarize the research progress on various compounds, including natural products and derivatives, that target the canonical Wnt pathway in lung cancer to develop safer and more targeted drugs or alternatives. Various natural products have been found to inhibit Wnt/β-catenin in various ways, such as through upstream and downstream intervention pathways, and have shown encouraging preclinical anti-tumor efficacy. Their diversity and low toxicity make them a popular research topic, laying the foundation for further combination therapies and drug development.

Enhancing chemotherapy for pancreatic cancer through efficient and sustained tumor microenvironment remodeling with a fibroblast-targeted nanosystem

Pancreatic cancer (PC) carries a poor prognosis among all malignancies and poses great challenges to clinical drug accessibility due to the severely fibrotic and hypoxic tumor microenvironment (TME). Therein, cancer-associated fibroblasts (CAFs), which are extremely abundant in PC, play a key role in forming the complex PC microenvironment. Therefore, a highly efficient TME reprogramming therapeutic paradigm that can specifically inhibit CAF function is urgently needed. Herein, we successfully developed a novel CAF-tailored nanosystem (Dex-GP-DOCA, DPD) loaded with a potent anti-fibrosis flavonoid compound (Quercetin, QUE), which possesses biological responsiveness to fibroblast activation protein alpha (FAP-α), prolonged TME remodeling and enhancement of clinical chemotherapeutics. Specifically, DPD/QUE allowed for extracellular matrix (ECM) reduction, vessel normalization, hypoxia-induced drug resistance reversal, and blockade of Wnt16 paracrine in CAFs. More importantly, this chemotherapy conducive microenvironment persisted for at least 8 days following treatment with DPD/QUE. It should also be noted that the effective and prolonged microenvironment modulation induced by DPD/QUE significantly improved the chemotherapy sensitivity of Abraxane and gemcitabine, the first-line chemotherapeutic drugs for PC, with inhibition rates increasing from 37.5% and 40.0% to 87.5% and 85.2%, respectively. Overall, our CAFs-targeted nanosystem showed promising prospects for remodeling the TME and facilitating chemotherapy for refractory pancreatic cancer.

Challenges and opportunities for improving the druggability of natural product: Why need drug delivery system?

Bioactive natural products (BNPs) are the marrow of medicinal plants, which are the secondary metabolites of organisms and have been the most famous drug discovery database. Bioactive natural products are famous for their enormous number and great safety in medical applications. However, BNPs are troubled by their poor druggability compared with synthesis drugs and are challenged as medicine (only a few BNPs are applied in clinical settings). In order to find a reasonable solution to improving the druggability of BNPs, this review summarizes their bioactive nature based on the enormous pharmacological research and tries to explain the reasons for the poor druggability of BNPs. And then focused on the boosting research on BNPs loaded drug delivery systems, this review further concludes the advantages of drug delivery systems on the druggability improvement of BNPs from the perspective of their bioactive nature, discusses why BNPs need drug delivery systems, and predicts the next direction.

Enhanced delivery of quercetin and doxorubicin using β-cyclodextrin polymer to overcome P-glycoprotein mediated multidrug resistance

In this study, we prepared a β-cyclodextrin polymer (β-CDP) co-loaded quercetin (QCT) and doxorubicin (DOX) nanocarrier (β-CDP/QD NCs) by freeze-dried method to combat P-glycoprotein (P-gp) mediated multidrug resistance (MDR) in KB-Ch^R 8-5 cancer cells. Various microscopic and spectroscopic techniques were employed to characterize the prepared nanocarrier. The molecular docking studies confirm the effective binding interactions of QCT and DOX with the synthesized β-CD polymer. The in vitro drug release study illustrates the sustainable release of DOX and QCT from the β-CDP nanocarrier. Further, we noticed that the QCT released from the β-CDP nanocarrier improved the intracellular availability of DOX via modulating P-gp drug efflux function in KB-Ch^R 8-5 cells and MCF-7/DOX cancer cells. Cell uptake results confirmed the successful internalization of DOX in KB-Ch^R 8-5 cells compared with free DOX. Cell-based assays such as nuclear condensation, alteration in the mitochondrial membrane potential (MMP), and apoptosis morphological changes confirmed the enhanced anticancer effect of β-CDP/QD NCs in the resistant cancer cells. Hence, QCT and DOX co-loaded β-CDP may be considered effective in achieving maximum cell death in the P-gp overexpressing MDR cancer cells.

Dual-drug codelivery nanosystems: An emerging approach for overcoming cancer multidrug resistance

Multidrug resistance (MDR) promotes tumor recurrence and metastasis and heavily reduces anticancer efficiency, which has become a primary reason for the failure of clinical chemotherapy. The mechanisms of MDR are so complex that conventional chemotherapy usually fails to achieve an ideal therapeutic effect and even accelerates the occurrence of MDR. In contrast, the combination of chemotherapy with dual-drug has significant advantages in tumor therapy. A novel dual-drug codelivery nanosystem, which combines dual-drug administration with nanotechnology, can overcome the application limitation of free drugs. Both the characteristics of nanoparticles and the synergistic effect of dual drugs contribute to circumventing various drug-resistant mechanisms in tumor cells. Therefore, developing dual-drug codelivery nanosystems with different multidrug-resistant mechanisms has an important reference value for reversing MDR and enhancing the clinical antitumor effect. In this review, the advantages, principles, and common codelivery nanocarriers in the application of dual-drug codelivery systems are summarized. The molecular mechanisms of MDR and the dual-drug codelivery nanosystems designed based on different mechanisms are mainly introduced. Meanwhile, the development prospects and challenges of codelivery nanosystems are also discussed, which provide guidelines to exploit optimized combined chemotherapy strategies in the future.

Interaction of quercetin and 5-fluorouracil: cellular and pharmacokinetic study

5-fluorouracil (5-FU) is a widely used chemotherapeutic agent, and its uncontrolled blood levels contribute to toxicity. Quercetin, as an important flavonoid, has many biological effects, including anti-tumor and anti-inflammatory features. The current study investigated the synergistic effect between 5-FU and quercetin using HT-29 cell line and fibroblast cells. Rats were assigned to two groups. The 5-FU/quercetin group received intraperitoneal quercetin (10 mg/kg) and the Tween was injected to the control group for 14 consecutive days. On the 15th day, both groups received 50 mg/kg of 5-FU. Upon the final injection, blood samples were obtained at different times. Pharmacokinetic parameters were evaluated using high-performance liquid chromatography (HPLC). The mean (±SD) of maximum plasma concentration (C_max) of 5-FU in combination therapy group was 3.10 ± 0.18 μg/ml and the area under the curve (AUC) was 153.89 ± 21.36, which increased by 113% and 128% compared to control group, respectively. Quercetin increased anti-tumor activity of 5-FU and enhanced C_max and AUC of 5-FU. These findings confirm the synergistic effects between quercetin and 5-FU at the usual doses in cancer treatment, which may lead to reduced toxicity.

Natural bioactive compounds-doxorubicin combinations targeting topoisomerase II-alpha: Anticancer efficacy and safety

Cancer is one of the leading causes of death worldwide, so pursuing effective and safe therapeutics for cancer is a key research objective nowadays. Doxorubicin (DOX) is one of the commonly prescribed chemotherapeutic agents that has been used to treat cancer with its antimitotic properties via inhibition of topoisomerase II (TOP2) activity. However, many problems hinder the broad use of DOX in clinical practice, including cardiotoxicity and drug resistance. Research in drug discovery has confirmed that natural bioactive compounds (NBACs) display a wide range of biological activities correlating to anticancer outcomes. The combination of NBACs has been seen to be an ideal candidate that might increase the effectiveness of DOX therapy and decreases its unfavorable adverse consequences. The current review discusses the chemo-modulatory mechanism and the protective effects of combined DOX with NBACs with a binding affinity (pKi) toward TOP2A more than pKi of DOX. This review will also discuss and emphasize the molecular mechanisms to provide a pathway for further studies to reveal other signaling pathways. Taken together, understanding the fundamental mechanisms and implications of combined therapy may provide a practical approach to battling cancer diseases.

Recent advances in flavonoid-based nanocarriers as an emerging drug delivery approach for cancer chemotherapy

Flavonoids are an interesting class of biomolecules, which exhibit cancer-inhibitory effects through both chemopreventive and chemotherapeutic activities. However, their therapeutic efficacy is affected by poor pharmacokinetics (PK) and biopharmaceutical attributes. One of the most promising approaches to resolve these issues is to formulate flavonoids in nanosystems. Different flavonoid nanoformulations have shown therapeutic superiority over free flavonoids. Functionalization of nanoparticles (NPs) further improves their therapeutic efficacy by facilitating site-specific delivery and reducing nonspecific toxicities. In this review, we highlight recent developments in the field of flavonoid-based NPs to gain translational insights into the potential applications of flavonoid-based nanocarriers in cancer management.

Co-Delivery System of Curcumin and Colchicine Using Functionalized Mesoporous Silica Nanoparticles Promotes Anticancer and Apoptosis Effects

Purpose: Many natural agents have a high anticancer potential, and their combination may be advantageous for improved anticancer effects. Such agents, however, often are not water soluble and do not efficiently target cancer cells, and the kinetics of their action is poorly controlled. One way to overcome these barriers is to combine natural agents with nanoparticles. Our aim in the current study was to fabricate an anticancer nanoformulation for co-delivery of two natural agents, curcumin (CR) and colchicine (CL), with a core-shell structure. Using cancer cell lines, we compared the anticancer efficacy between the combination and a nanoformulation with CL alone. Methods: For the single-drug nanoformulation, we used phosphonate groups to functionalize mesoporous silica nanoparticles (MSNs) and loaded the MSNs with CL. Additional loading of this nanoformulation with CR achieved the co-delivery format. To create the structure with a core shell, we selected a chitosan−cellulose mixture conjugated with targeting ligands of folic acid for the coating. For evaluating anticancer and apoptosis effects, we assessed changes in important genes and proteins in apoptosis (p53, caspase-3, Bax, Bcl-2) in several cell lines (MCF-7, breast adenocarcinoma; HCT-116, colon carcinoma; HOS, human osteosarcoma; and A-549, non−small cell lung cancer). Results: Nanoformulations were successfully synthesized and contained 10.9 wt.% for the CL single-delivery version and 18.1 wt.% for the CL+CR co-delivery nanoformulation. Anticancer effects depended on treatment, cell line, and concentration. Co-delivery nanoformulations exerted anticancer effects that were significantly superior to those of single delivery or free CL or CR. Anticancer effects by cell line were in the order of HCT-116 > A549 > HOS > MCF-7. The lowest IC50 value was obtained for the nanoformulation consisting of CL and CR coated with a polymeric shell conjugated with FA (equivalent to 4.1 ± 0.05 µg/mL). With dual delivery compared with the free agents, we detected strongly increased p53, caspase-3, and Bax expression, but inhibition of Bcl-2, suggesting promotion of apoptosis. Conclusions: Our findings, although preliminary, indicate that the proposed dual delivery nanoformulation consisting of nanocore: MSNs loaded with CL and CR and coated with a shell of chitosan−cellulose conjugated folic acid exerted strong anticancer and apoptotic effects with potent antitumor activity against HCT-116 colon cells. The effect bested CL alone. Evaluating and confirming the efficacy of co-delivery nanoformulations will require in vivo studies.

Dual role of quercetin in enhancing the efficacy of cisplatin in chemotherapy and protection against its side effects: a review

Chemotherapy has opened a new window in cancer therapy. However, the resistance of cancer cells has dramatically reduced the efficacy of chemotherapy. Cisplatin is a chemotherapeutic agent and its potential in cancer therapy has been restricted by resistance of cancer cells. As a consequence, the scientists have attempted to find new strategies in elevating chemotherapy efficacy. Due to great anti-tumour activity, naturally occurring compounds are of interest in polychemotherapy. Quercetin is a flavonoid with high anti-tumour activity against different cancers that can be used with cisplatin to enhance its efficacy and also are seen to sensitise cancer cells into chemotherapy. Furthermore, cisplatin has side effects such as nephrotoxicity and ototoxicity. Administration of quercetin is advantageous in reducing the adverse effects of cisplatin without compromising its anti-tumour activity. In this review, we investigate the dual role of quercetin in enhancing anti-tumour activity of cisplatin and simultaneous reduction in its adverse effects.

Nano-drug co-delivery system of natural active ingredients and chemotherapy drugs for cancer treatment: a review

Chemotherapy drugs have been used for a long time in the treatment of cancer, but serious side effects are caused by the inability of the drug to be solely delivered to the tumor when treating cancer with chemotherapy. Natural products have attracted more and more attention due to the antitumor effect in multiple ways, abundant resources and less side effects. Therefore, the combination of natural active ingredients and chemotherapy drugs may be an effective antitumor strategy, which can inhibit the growth of tumor and multidrug resistance, reduce side effects of chemotherapy drugs. Nano-drug co-delivery system (NDCDS) can play an important role in the combination of natural active ingredients and chemotherapy drugs. This review provides a comprehensive summary of the research status and application prospect of nano-delivery strategies for the combination of natural active ingredients and chemotherapy drugs, aiming to provide a basis for the development of anti-tumor drugs.

Recent Trends in Nanomedicine-Based Strategies to Overcome Multidrug Resistance in Tumors

Cancer is the leading cause of economic and health burden worldwide. The commonly used approaches for the treatment of cancer are chemotherapy, radiotherapy, and surgery. Chemotherapy frequently results in undesirable side effects, and cancer cells may develop resistance. Combating drug resistance is a challenging task in cancer treatment. Drug resistance may be intrinsic or acquired and can be due to genetic factors, growth factors, the increased efflux of drugs, DNA repair, and the metabolism of xenobiotics. The strategies used to combat drug resistance include the nanomedicine-based targeted delivery of drugs and genes using different nanocarriers such as gold nanoparticles, peptide-modified nanoparticles, as well as biomimetic and responsive nanoparticles that help to deliver payload at targeted tumor sites and overcome resistance. Gene therapy in combination with chemotherapy aids in this respect. siRNA and miRNA alone or in combination with chemotherapy improve therapeutic response in tumor cells. Some natural substances, such as curcumin, quercetin, tocotrienol, parthenolide, naringin, and cyclosporin-A are also helpful in combating the drug resistance of cancer cells. This manuscript summarizes the mechanism of drug resistance and nanoparticle-based strategies used to combat it.

Combination Anticancer Therapies Using Selected Phytochemicals

Cancer is still one of the most widespread diseases globally, it is considered a vital health challenge worldwide and one of the main barriers to long life expectancy. Due to the potential toxicity and lack of selectivity of conventional chemotherapeutic agents, discovering alternative treatments is a top priority. Plant-derived natural products have high potential in cancer treatment due to their multiple mechanisms of action, diversity in structure, availability in nature, and relatively low toxicity. In this review, the anticancer mechanisms of the most common phytochemicals were analyzed. Furthermore, a detailed discussion of the anticancer effect of combinations consisting of natural product or natural products with chemotherapeutic drugs was provided. This review should provide a strong platform for researchers and clinicians to improve basic and clinical research in the development of alternative anticancer medicines.

Opportunities and challenges for co-delivery nanomedicines based on combination of phytochemicals with chemotherapeutic drugs in cancer treatment

The therapeutic limitations such as insufficient efficacy, drug resistance, metastasis, and undesirable side effects are frequently caused by the long duration monotherapy based on chemotherapeutic drugs. multiple combinational anticancer strategies such as nucleic acids combined with chemotherapeutic agents, chemotherapeutic combinations, chemotherapy and tumor immunotherapy combinations have been embraced, holding great promise to counter these limitations, while still taking including some potential risks. Nowadays, an increasing number of research has manifested the anticancer effects of phytochemicals mediated by modulating cancer cellular events directly as well as the tumor microenvironment. Specifically, these natural compounds exhibited suppression of cancer cell proliferation, apoptosis, migration and invasion of cancer cells, P-glycoprotein inhibition, decreasing vascularization and activation of tumor immunosuppression. Due to the low toxicity and multiple modulation pathways of these phytochemicals, the combination of chemotherapeutic agents with natural compounds acts as a novel approach to cancer therapy to increase the efficiency of cancer treatments as well as reduce the adverse consequences. In order to achieve the maximized combination advantages of small-molecule chemotherapeutic drugs and natural compounds, a variety of functional nano-scaled drug delivery systems, such as liposomes, host-guest supramolecules, supramolecules, dendrimers, micelles and inorganic systems have been developed for dual/multiple drug co-delivery. These co-delivery nanomedicines can improve pharmacokinetic behavior, tumor accumulation capacity, and achieve tumor site-targeting delivery. In that way, the improved antitumor effects through multiple-target therapy and reduced side effects by decreasing dose can be implemented. Here, we present the synergistic anticancer outcomes and the related mechanisms of the combination of phytochemicals with small-molecule anticancer drugs. We also focus on illustrating the design concept, and action mechanisms of nanosystems with co-delivery of drugs to synergistically improve anticancer efficacy. In addition, the challenges and prospects of how these insights can be translated into clinical benefits are discussed.

Co-encapsulation of flavonoids with anti-cancer drugs: a challenge ahead

Flavonoids have been considered as promising molecules for cancer treatment due to their pleiotropic properties such as anti-carcinogenic, anti-angiogenic or efflux proteins inhibition. However, due to their lipophilic properties and their chemical instability, vectorization seems compulsory to administer flavonoids. Flavonoids have been co-encapsulated with other anti-cancer agents in a broad range of nanocarriers aiming to i) achieve a synergistic/additive effect at the tumor site, ii) delay drug resistance apparition by combining agents with different action mechanisms or iii) administer a lower dose of the anti-cancer drug, reducing its toxicity. However, co-encapsulation could lead to a change in the nanoparticles' diameter and drug-loading, as well as a decrease in their stability during storage. The preparation process should also take into accounts the physico-chemical properties of both the flavonoid and the anti-cancer agent. Moreover, the co-encapsulation could affect the release and activity of each drug. This review aims to study the formulation, preparation and characterization strategies of these co-loaded nanomedicines, as well as their stability. The in vitro assays to predict the nanomedicines' behavior in biological fluids, as well as their in vivo efficacy, are also discussed. A special focus concerns the evaluation of their synergistic effect on tumor treatment.

Strategies and Mechanism in Reversing Intestinal Drug Efflux in Oral Drug Delivery

Efflux transporters distributed at the apical side of human intestinal epithelial cells actively transport drugs from the enterocytes to the intestinal lumen, which could lead to extremely poor absorption of drugs by oral administration. Typical intestinal efflux transporters involved in oral drug absorption process mainly include P-glycoprotein (P-gp), multidrug resistance proteins (MRPs) and breast cancer resistance protein (BCRP). Drug efflux is one of the most important factors resulting in poor absorption of oral drugs. Caco-2 monolayer and everted gut sac are sued to accurately measure drug efflux in vitro. To reverse intestinal drug efflux and improve absorption of oral drugs, a great deal of functional amphiphilic excipients and inhibitors with the function of suppressing efflux transporters activity are generalized in this review. In addition, different strategies of reducing intestinal drugs efflux such as silencing transporters and the application of excipients and inhibitors are introduced. Ultimately, various nano-formulations of improving oral drug absorption by inhibiting intestinal drug efflux are discussed. In conclusion, this review has significant reference for overcoming intestinal drug efflux and improving oral drug absorption.

Reactive Oxygen Species-Responsive Nanococktail With Self-Amplificated Drug Release for Efficient Co-Delivery of Paclitaxel/Cucurbitacin B and Synergistic Treatment of Gastric Cancer

Application of drug combinations is a powerful strategy for the therapy of advanced gastric cancer. However, the clinical use of such combinations is greatly limited by the occurrence of severe systemic toxicity. Although polymeric-prodrug-based nanococktails can significantly reduce toxicity of drugs, they have been shown to have low intracellular drug release. To balance between efficacy and safety during application of polymeric-prodrug-based nanococktails, a reactive oxygen species (ROS)-responsive nanococktail (PCM) with self-amplification drug release was developed in this study. In summary, PCM micelles were co-assembled from ROS-sensitive cucurbitacin B (CuB) and paclitaxel (PTX) polymeric prodrug, which were fabricated by covalently grafting PTX and CuB to dextran via an ROS-sensitive linkage. To minimize the side effects of the PCM micelles, a polymeric-prodrug strategy was employed to prevent premature leakage. Once it entered cancer cells, PCM released CuB and PTX in response to ROS. Moreover, the released CuB further promoted ROS generation, which in turn enhanced drug release for better therapeutic effects. In vivo antitumor experiments showed that the PCM-treated group had lower tumor burden (tumor weight was reduced by 92%), but bodyweight loss was not significant. These results indicate that the developed polymeric prodrug, with a self-amplification drug release nanococktail strategy, can be an effective and safe strategy for cancer management.

Applications and Biocompatibility of Mesoporous Silica Nanocarriers in the Field of Medicine

Mesoporous silica nanocarrier (MSN) preparations have a wide range of medical applications. Studying the biocompatibility of MSN is an important part of clinical transformation. Scientists have developed different types of mesoporous silica nanocarriers (MSNs) for different applications to realize the great potential of MSNs in the field of biomedicine, especially in tumor treatment. MSNs have achieved good results in diagnostic bioimaging, tissue engineering, cancer treatment, vaccine development, biomaterial application and diagnostics. MSNs can improve the therapeutic efficiency of drugs, introduce new drug delivery strategies, and provide advantages that traditional drugs lack. It is necessary not only to innovate MSNs but also to comprehensively understand their biological distribution. In this review, we summarize the various medical uses of MSN preparations and explore the factors that affect their distribution and biocompatibility in the body based on metabolism. Designing more reasonable therapeutic nanomedicine is an important task for the further development of the potential clinical applications of MSNs.

Modern Nanocarriers as a Factor in Increasing the Bioavailability and Pharmacological Activity of Flavonoids

This review is devoted to modern systems of nanocarriers that ensure the targeted delivery of flavonoids to various organs and systems. Flavonoids have wide range of effects on the human body due to their antioxidant, anti-inflammatory, antitumor, antimicrobial, antiplatelet and other types of activity. However, the low bioavailability of flavonoids significantly limits their practical application. To overcome this disadvantage, serious efforts have been made in recent years to develop nanoscale carriers for flavonoids. This is particularly important in view of the known antitumor effect of these compounds, which allows them to target tumor cells without affecting surrounding healthy tissues. Nanocarriers provide increased penetration of biologicals into specific organs in combination with controlled and prolonged release, which markedly improves their effectiveness. This review summarizes data on the use of phytosomes, lipid-based nanoparticles, as well as polymeric and inorganic nanoparticles; their advantages and drawbacks are analyzed; the prospect of their use is discussed that opens new possibilities for the clinical application of flavonoids.

An Up-to-Date Review of Natural Nanoparticles for Cancer Management

Cancer represents one of the leading causes of morbidity and mortality worldwide, imposing an urgent need to develop more efficient treatment alternatives. In this respect, much attention has been drawn from conventional cancer treatments to more modern approaches, such as the use of nanotechnology. Extensive research has been done for designing innovative nanoparticles able to specifically target tumor cells and ensure the controlled release of anticancer agents. To avoid the potential toxicity of synthetic materials, natural nanoparticles started to attract increasing scientific interest. In this context, this paper aims to review the most important natural nanoparticles used as active ingredients (e.g., polyphenols, polysaccharides, proteins, and sterol-like compounds) or as carriers (e.g., proteins, polysaccharides, viral nanoparticles, and exosomes) of various anticancer moieties, focusing on their recent applications in treating diverse malignancies.

Polysaccharide/mesoporous silica nanoparticle-based drug delivery systems: A review

Mesoporous silica nanoparticles (MSNs) have been well-researched in the design and fabrication of advanced drug delivery systems (DDSs) due to their advantages such as good biocompatibility, large specific surface area and pore volume for drug loading, easily surface modification, adjusted size and good thermal/chemical stability. For MSN-based DDSs, gate materials are also necessary. And natural polysaccharides, one kind of the most abundant natural resource, have been widely applied as the "gatekeepers" in MSN-based DDSs. Polysaccharides are cheap and rich in sources with good biocompatibility, and some of them have important biological functions. In this review article, polysaccharides including chitosan, hyaluronic acid, sodium alginate and dextran, et al. are briefly introduced. And the preparation processes and properties such as controlled drug release, cancer targeting and disease diagnosis of functional polysaccharide/MSN-based DDSs are discussed.

Emerging nanoformulation strategies for phytocompounds and applications from drug delivery to phototherapy to imaging

Over thousands of years, natural bioactive compounds derived from plants (bioactive phytocompounds, BPCs) have been used worldwide to address human health issues. Today, they are a significant resource for drug discovery in the development of modern medicines. Although many BPCs have promising biological activities, most of them cannot be effectively utilized in drugs for therapeutic applications because of their inherent limitations of low solubility, structural instability, short half-life, poor bioavailability, and non-specific distribution to organs. Researchers have utilized emerging nanoformulation (NF) technologies to overcome these limitations as they have demonstrated great potential to improve the solubility, stability, and pharmacokinetic and pharmacodynamic characteristics of BPCs. This review exemplifies NF strategies for resolving the issues associated with BPCs and summarizes recent advances in their preclinical and clinical applications for imaging and therapy. This review also highlights how innovative NF technologies play a leading role in next-generation BPC-based drug development for extended therapeutic applications. Finally, this review discusses the opportunities to take BPCs with meaningful clinical impact from bench to bedside and extend the patent life of BPC-based medicines with new formulations or application to new adjacent diseases beyond the primary drug indications.

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Natural bioactive phytocompounds derived from plants have been used worldwide to address human health issues. However, most of them cannot be effectively utilized in drugs for therapeutic applications because of their inherent limitations.

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Nanoformulation approach has recently been underlined as an emerging pharmaceutical strategy to overcome the intrinsic drawbacks of bioactive phytocompounds.

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Various types of nanoformulation and their up-to-date applications for targeted delivery, phototherapy, and imaging are reviewed. Finally, their clinical implications for the repurposing of bioactive phytocompounds are deliberated.

Advances in understanding the role of P-gp in doxorubicin resistance: Molecular pathways, therapeutic strategies, and prospects

P-glycoprotein (P-gp) is a drug efflux transporter that triggers doxorubicin (DOX) resistance. In this review, we highlight the molecular avenues regulating P-gp, such as Nrf2, HIF-1α, miRNAs, and long noncoding (lnc)RNAs, to reveal their participation in DOX resistance. These antitumor compounds and genetic tools synergistically reduce P-gp expression. Furthermore, ATP depletion impairs P-gp activity to enhance the antitumor activity of DOX. Nanoarchitectures, including liposomes, micelles, polymeric nanoparticles (NPs), and solid lipid nanocarriers, have been developed for the co-delivery of DOX with anticancer compounds and genes enhancing DOX cytotoxicity. Surface modification of nanocarriers, for instance with hyaluronic acid (HA), can promote selectivity toward cancer cells. We discuss these aspects with a focus on P-gp expression and activity.

Current Advances and Outlook in Gastric Cancer Chemoresistance: A Review

BACKGROUND

Surgical resection of the lesion is the standard primary treatment of gastric cancer. Unfortunately, most patients are already in the advanced stage of the disease when they are diagnosed with gastric cancer. Alternative therapies, such as radiation therapy and chemotherapy, can achieve only very limited benefits. The emergence of cancer drug resistance has always been the major obstacle to the cure of tumors. The main goal of modern cancer pharmacology is to determine the underlying mechanism of anticancer drugs.

OBJECTIVE

Here, we mainly review the latest research results related to the mechanism of chemotherapy resistance in gastric cancer, the application of natural products in overcoming the chemotherapy resistance of gastric cancer, and the new strategies currently being developed to treat tumors based on immunotherapy and gene therapy.

CONCLUSION

The emergence of cancer drug resistance is the main obstacle in achieving alleviation and final cure for gastric cancer. Mixed therapies are considered to be a possible way to overcome chemoresistance. Natural products are the main resource for discovering new drugs specific for treating chemoresistance, and further research is needed to clarify the mechanism of natural product activity in patients. .

Resveratrol-modified mesoporous silica nanoparticle for tumor-targeted therapy of gastric cancer

Resveratrol (Res) has been shown to exhibit anti-cancer properties in gastric cancer. However, its clinical application is limited by its poor pharmacokinetics, stability, and low solubility. Hence, this study aimed to explore and verify a better delivery system for gastric cancer therapy. Using transmission electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and ultraviolet (UV) spectrometry, we observed the shape and encapsulation of resveratrol-modified mesoporous silica nanoparticles (MSN-Res) that were synthesized by chemical methods. To explore the anti-cancer effects of these MSN-Res in vivo and in vitro, we established AGS and HGC-27 tumor-bearing mouse models. Meanwhile, the proliferation of gastric cancer cells in vitro and in vivo was assessed by Cell Counting Kit-8, EdU, and Ki-67 immunohistochemical staining methods, while cellular apoptosis, and invasion and migration were detected by TdT-mediated dUTP nick end labeling (TUNEL) and Transwell assays, respectively. FTIR and UV results showed that we successfully synthesized and loaded drugs. Safety evaluation experiments showed that neither MSN-SH nor MSN-Res had toxic effects on the normal tissues of animals. Moreover, in vitro experiments revealed that MSN-Res significantly inhibited the proliferation, invasion, and migration of gastric cancer cells. Furthermore, TUNEL assay showed that MSN-Res promoted apoptosis in gastric cancer. These results were confirmed by the nude mouse tumorigenesis experiment. In conclusion, we demonstrated that MSN-Res showed better inhibitory effect on the development of gastric cancer than Res alone, indicating that MSN-Res could be a promising drug delivery system for gastric cancer treatment.

Phytochemicals reverse P-glycoprotein mediated multidrug resistance via signal transduction pathways

P-glycoprotein, encoded by ATP-binding cassette transporters B1 gene (ABCB1), renders multidrug resistance (MDR) during cancer chemotherapy. Several synthetic small molecule inhibitors affect P-glycoprotein (P-gp) transport function in MDR tumor cells. However, inhibition of P-gp transport function adversely accumulates chemotherapeutic drugs in non-target normal tissues. Moreover, most small-molecule P-gp inhibitors failed in the clinical trials due to the low therapeutic window at the maximum tolerated dose. Therefore, downregulation of ABCB1-gene expression (P-gp) in tumor tissues seems to be a novel approach rather than inhibiting its transport function for the reversal of multidrug resistance (MDR). Several plant-derived phytochemicals modulate various signal transduction pathways and inhibit translocation of transcription factors, thereby reverses P-gp mediated MDR in tumor cells. Therefore, phytochemicals may be considered an alternative to synthetic small molecule P-gp inhibitors for the reversal of MDR in cancer cells. This review discussed the role of natural phytochemicals that modulate ABCB1 expression through various signal transduction pathways in MDR cancer cells. Therefore, modulating the cell signaling pathways by phytochemicals might play crucial roles in modulating ABCB1 gene expression and the reversal of MDR.

Nanoplatform-based natural products co-delivery system to surmount cancer multidrug-resistant

The emergence of multidrug resistance (MDR) in malignant tumors is the primary reason for invalid chemotherapy. Antitumor drugs are often adversely affected by the MDR of tumor cells. Treatments using conventional drugs, which have specific drug targets, hardly regulate the complex signaling pathway of MDR cells because of the complex formation mechanism of MDR. However, natural products have positive advantages, such as high efficiency, low toxicity, and ability to target multiple mechanism pathways associated with MDR. Natural products, as MDR reversal agents, synergize with chemotherapeutics and enhance the sensitivity of tumor cells to chemotherapeutics, and the co-delivery of natural products and antitumor drugs with nanocarriers maximizes the synergistic effects against MDR in tumor cells. This review summarizes the molecular mechanisms of MDR, the advantages of natural products combined with chemotherapeutics in offsetting complicated MDR mechanisms, and the types and mechanisms of natural products that are potential MDR reversal modulators. Meanwhile, aiming at the low bioavailability of cocktail combined natural products and chemotherapeutic in vivo, the advantages of nanoplatform-based co-delivery system and recent research developments are illustrated on the basis of our previous research. Finally, prospective horizons are analyzed, which are expected to considerably improve the nano-co-delivery of natural products and chemotherapeutic systems for MDR reversal in cancer.

The Ph paradigm in cancer

Malignant tissues show a peculiar feature regarding pH: while normal tissues have a higher extracellular pH than intracellular pH, in cancer is exactly the opposite. This phenomenon is called the inversion of the pH gradient and is now considered a hallmark of malignancy. For some time, this inverted pH gradient was believed to be a secondary effect of cancer. Now, it is becoming clear that pH inversion is not an innocent consequence, but a key player in the etiopathogenesis of cancer. Therefore, addressing this issue as part of an integral treatment of neoplasia should be a necessary step for improving cancer patients' outcomes. However, the knowledge acquired in this regard through basic research has not reached bedside treatments. The most striking fact is that there are repurposed drugs and nutraceuticals with low or no toxicity that can modify the pH gradient inversion. However, these drugs have not even been tested in cancer treatment.

Protective Effect of Quercetin Nanoemulsion on 5-Fluorouracil-Induced Oral Mucositis in Mice

The target of this study was to evaluate the efficacy, histopathological, oxidative stress, and molecular effects of quercetin (QRC) in mice with oral mucositis induced by 5-fluorouracil (5-FU). Thirty-six albino male mice with oral mucositis induced by 5-FU as a chemotherapeutic agent were used in this study. The animals were randomly divided into 6 groups: control group, mucositis (MUC) group, pretreatment group, posttreatment group, and two last groups including nanoemulsion form of QRC with a dose of 5 mg/kg in both pretreatment and posttreatment. In the present evaluation, fewer oral lesions were observed in the QRC posttreatment groups compared to the pretreatment and nanoemulsion receiving groups. In the SOD assay, the most significant difference was observed in the posttreatment nanogroup (41.073 ± 1.24) and pretreatment nanogroup (43.453 ± 2.60) in comparison to the 5-FU group (30.897 ± 1.93). The results of CAT assay also showed a significant difference in nano-posttreatment (124.60 ± 10.85), posttreatment (135.4 ± 9.82), and nano-pretreatment groups (128.80 ± 7.20) compared to the 5-FU group (55.07 ± 8.91). The expression of inflammatory genes such as Hif-1α and NfκB in this group was lower than in the other groups, although this difference was not significant. It seems that the use of QRC can improve the treatment process of oral mucositis induced by 5-FU.

Research Progress in Flavonoids as Potential Anticancer Drug Including Synergy with Other Approaches

BACKGROUND

In chemotherapy for cancer, conventional drugs aim to target the rapidly growing and dividing cells at the early stages. However, at an advanced stage, cancer cells become less susceptible because of the multidrug resistance and the recruitment of alternative salvage pathways for their survival. Besides, owing to target non-selectivity, healthy proliferating cells also become vulnerable to the damage. The combination therapies offered using flavonoids to cure cancer not only exert an additive effect against cancer cells by targetting supplementary cell carnage pathways but also hampers the drug resistance mechanisms. Thus, the review aims to discuss the potential and pharmacokinetic limitations of flavonoids in cancer treatment. Further successful synergistic studies reported using flavonoids to treat cancer has been described along with potential drug delivery systems.

METHODS

A literature search was done by exploring various online databases like Pubmed, Scopus, and Google Scholar with the specific keywords like "Anticancer drugs", "flavonoids", "oncology research", and "pharmacokinetics".

RESULTS

Dietary phytochemicals, mainly flavonoids, hinder cell signalling responsible for multidrug resistance and cancer progression, primarily targeting cancer cells sparing normal cells. Such properties establish flavonoids as a potential candidate for synergistic therapy. However, due to low absorption and high metabolism rates, the bioavailability of flavonoids becomes a challenge. Such challenges may be overcome using novel approaches like derivatization, and single or co-delivery nano-complexes of flavonoids with conventional drugs. These new approaches may improve the pharmacokinetic and pharmacodynamic of flavonoids.

CONCLUSION

This review highlights the application of flavonoids as a potential anticancer phytochemical class in combination with known anti-cancer drugs/nanoparticles. It also discusses flavonoid's pharmacokinetics and pharmacodynamics issues and ways to overcome such issues. Moreover, it covers successful methodologies employed to establish flavonoids as a safe and effective phytochemical class for cancer treatment.

Adaptive Mechanisms of Tumor Therapy Resistance Driven by Tumor Microenvironment

Cancer is a disease which frequently has a poor prognosis. Although multiple therapeutic strategies have been developed for various cancers, including chemotherapy, radiotherapy, and immunotherapy, resistance to these treatments frequently impedes the clinical outcomes. Besides the active resistance driven by genetic and epigenetic alterations in tumor cells, the tumor microenvironment (TME) has also been reported to be a crucial regulator in tumorigenesis, progression, and resistance. Here, we propose that the adaptive mechanisms of tumor resistance are closely connected with the TME rather than depending on non-cell-autonomous changes in response to clinical treatment. Although the comprehensive understanding of adaptive mechanisms driven by the TME need further investigation to fully elucidate the mechanisms of tumor therapeutic resistance, many clinical treatments targeting the TME have been successful. In this review, we report on recent advances concerning the molecular events and important factors involved in the TME, particularly focusing on the contributions of the TME to adaptive resistance, and provide insights into potential therapeutic methods or translational medicine targeting the TME to overcome resistance to therapy in clinical treatment.

Molecular targeted treatment and drug delivery system for gastric cancer

Gastric cancer is still a major cancer worldwide. The early diagnosis rate of gastric cancer in most high incidence countries is low. At present, the overall treatment effect of gastric cancer is poor, and the median overall survival remains low. Most of the patients with gastric cancer are in an advanced stage when diagnosed, and drug treatment has become the main means. Thus, new targeted drugs and therapeutic strategies are the hope of improving the therapeutic effect of gastric cancer. In this review, we summarize the new methods and advances of targeted therapy for gastric cancer, including novel molecular targeted therapeutic agents and drug delivery systems, with a major focus on the development of drug delivery systems (drug carriers and targeting peptides). Elaborating these new methods and advances will contribute to the management of gastric cancer.

Delivery of Natural Agents by Means of Mesoporous Silica Nanospheres as a Promising Anticancer Strategy

Natural prodrugs derived from different natural origins (e.g., medicinal plants, microbes, animals) have a long history in traditional medicine. They exhibit a broad range of pharmacological activities, including anticancer effects in vitro and in vivo. They have potential as safe, cost-effective treatments with few side effects, but are lacking in solubility, bioavailability, specific targeting and have short half-lives. These are barriers to clinical application. Nanomedicine has the potential to offer solutions to circumvent these limitations and allow the use of natural pro-drugs in cancer therapy. Mesoporous silica nanoparticles (MSNs) of various morphology have attracted considerable attention in the search for targeted drug delivery systems. MSNs are characterized by chemical stability, easy synthesis and functionalization, large surface area, tunable pore sizes and volumes, good biocompatibility, controlled drug release under different conditions, and high drug-loading capacity, enabling multifunctional purposes. In vivo pre-clinical evaluations, a significant majority of results indicate the safety profile of MSNs if they are synthesized in an optimized way. Here, we present an overview of synthesis methods, possible surface functionalization, cellular uptake, biodistribution, toxicity, loading strategies, delivery designs with controlled release, and cancer targeting and discuss the future of anticancer nanotechnology-based natural prodrug delivery systems.

Carbon nano-onion-mediated dual targeting of P-selectin and P-glycoprotein to overcome cancer drug resistance

The transmembrane P-glycoprotein (P-gp) pumps that efflux drugs are a major mechanism of cancer drug resistance. They are also important in protecting normal tissue cells from poisonous xenobiotics and endogenous metabolites. Here, we report a fucoidan-decorated silica-carbon nano-onion (FSCNO) hybrid nanoparticle that targets tumor vasculature to specifically release P-gp inhibitor and anticancer drug into tumor cells. The tumor vasculature targeting capability of the nanoparticle is demonstrated using multiple models. Moreover, we reveal the superior light absorption property of nano-onion in the near infrared region (NIR), which enables triggered drug release from the nanoparticle at a low NIR power. The released inhibitor selectively binds to P-gp pumps and disables their function, which improves the bioavailability of anticancer drug inside the cells. Furthermore, free P-gp inhibitor significantly increases the systemic toxicity of a chemotherapy drug, which can be resolved by delivering them with FSCNO nanoparticles in combination with a short low-power NIR laser irradiation.

Quercetin nanoformulations: a promising strategy for tumor therapy

Phytochemicals as dietary constituents are being widely explored for the prevention and treatment of various diseases. Quercetin, a major constituent of various dietary products, has attracted extensive interest due to its anti-proliferative capability, reversal of multidrug resistance, autophagy promotion and tumor microenvironment modulation on different cancer types. Although quercetin has shown potent medical value, its application as an antitumor drug is limited. Problems like poor solubility, bioavailability and stability, short half-life and weak tumor-targeting biodistribution make quercetin an unreliable candidate for cancer therapy. Nanoparticle based platforms have shown a number of advantages in delivering a hydrophobic drug like quercetin to diseased tissues. Quercetin nanoparticles have demonstrated high encapsulation efficiency, stability, sustained release, prolonged circulation time, improved accumulation at tumor sites and therapeutic efficiency. Moreover, a combination of quercetin with other diagnostic or therapeutic agents in one nanocarrier has achieved enhancements in detecting or treating tumors. In this review, we have tried to summarize the pharmacological activities of quercetin with regard to tumor cells and microenvironments in vitro and in vivo. Furthermore, various nanoformulations have been highlighted for quercetin delivery for cancer treatment. These results suggest that quercetin nanoparticles may be a promising antitumor therapeutic agent.

Role of flavonoids against adriamycin toxicity

Doxorubicin (DOX), or adriamycin, is an anthracycline antineoplastic drug widely used in the chemotherapy of a large variety of cancers due to its potency and action spectrum. However, its use is limited by the toxicity on healthy cells and its acute and chronic side effects. One of the developed strategies to attenuate DOX toxicity is the combined therapy with bioactive compounds such as flavonoids. This review embraces the role of flavonoids on DOX treatment side effects. Protective properties of some flavonoidss against DOX toxicity have been investigated and observed mainly in heart but also in liver, kidney, brain, testis or bone marrow. Protective mechanisms involve reduction of oxidative stress by decrease of ROS levels and/or increase antioxidant defenses and interferences with autophagy, apoptosis and inflammation. Studies in cancer cells have reported that the anticancer activity of DOX was not compromised by the flavonoids. Moreover, some of them increased DOX efficiency as anti-cancer drug even in multidrug resistant cells.

Nanostructured Lipid Carriers Delivering Sorafenib to Enhance Immunotherapy Induced by Doxorubicin for Effective Esophagus Cancer Therapy

The tumor microenvironment (TME) plays a significant role in weakening the effect of cancer immunotherapy, which calls for the remodeling of TME. Herein, we fabricated a nanostructured lipid carrier (NLC) to codeliver doxorubicin (Dox) and sorafenib (Sfn) as a drug delivery system (NLC/D-S). The Sfn was expected to regulate the TME of esophagus cancer. As a result, the immune response induced by Dox-related immunogenicity cell death could be fully realized. Our results demonstrated that Sfn was able to remodel the TME through downregulation of regulatory T cells (Treg), activation of effector T cells, and relieving of PD-1 expression, which achieved synergistic effect on the inhibition of primary tumor but also subsequent strong immune response on the regeneration of distant tumor.

iRGD-targeted hybrid nanoparticles reverses multi-drug resistant to effectively combat liver cancer

The off-target delivery as well as multi-drug resistance (MDR) are generally recognised as two keys difficulties responsible for the poor performance of chemotherapy in clinical treatment of cancer. With the aim to address the problems, we herein constructed iRGD modified and lipid-coated silica (LSC) nanoparticles co-delivering Ca²⁺ channel siRNA and adriamycin (Adr) to reverse the MDR in liver cancer (LSC/R-A). The iRGD decoration was suggested to elevate the tumour accumulation of the drug delivery system (DDS). In addition, the introduction of Ca²⁺ channel siRNA was proved to reverse the MDR within the cells of cancer by regulation the T-type Ca²⁺ channels. Our results showed that decreased expression of T-type Ca²⁺ channels resulted in lowered cytosolic Ca²⁺ level responsible for the cell cycle arrest (at G0/G1 phase) as well as elevated cellular drug retention in HepG2/Adr. B in vitro/in vivo experiments revealed that LSC/R-A exerted highly elevated therapeutic outcome on HepG2/Adr, than administration of single siRNA or Adr.

Nanoformulated Ajwa (Phoenix Dactylifera) Bioactive Compounds Improve the Safety of Doxorubicin without Compromising its Anticancer Efficacy in Breast Cancer

One of the major causes of women's death in the world is breast cancer. Consequently, numerous regimens for the control of this severe disease have been created. The chemotherapeutic agent doxorubicin (DOX) is frequently used to treat breast cancer, but DOX can also cause cardiotoxic effects that lead to heart failure. Therefore, many research studies have been done to find a natural product that effectively potentiates or does not interfere with DOX's anticancer effect and protects against its cardiotoxicity. We studied the impact of combined nanoformulated Ajwa (Phoenix dactylifera) selected bioactive compounds (BAC) rutin (R) and quercetin (Q) in nude mice breast cancer xenografts on DOX-mediated anticancer efficacy. We also studied if this Ajwa BAC could safeguard against DOX-mediated cardiomyopathies by evaluating plasma cardiac troponin-I (cTn-I) levels and cardiac histopathology. Nanoformulated Ajwa BAC effectively alleviated weight loss induced by DOX in mice and significantly decreased the elevated cTn-I. Furthermore, 5 mg RQ-NPs/kg of nude mice that subcutaneously daily injected for 11 days, attenuated the histopathological alterations induced in cardiac muscles due to DOX without any interference with the anticancer effects of DOX against breast cancer.

Small Molecule Wnt Pathway Modulators from Natural Sources: History, State of the Art and Perspectives

The Wnt signaling is one of the major pathways known to regulate embryonic development, tissue renewal and regeneration in multicellular organisms. Dysregulations of the pathway are a common cause of several types of cancer and other diseases, such as osteoporosis and rheumatoid arthritis. This makes Wnt signaling an important therapeutic target. Small molecule activators and inhibitors of signaling pathways are important biomedical tools which allow one to harness signaling processes in the organism for therapeutic purposes in affordable and specific ways. Natural products are a well known source of biologically active small molecules with therapeutic potential. In this article, we provide an up-to-date overview of existing small molecule modulators of the Wnt pathway derived from natural products. In the first part of the review, we focus on Wnt pathway activators, which can be used for regenerative therapy in various tissues such as skin, bone, cartilage and the nervous system. The second part describes inhibitors of the pathway, which are desired agents for targeted therapies against different cancers. In each part, we pay specific attention to the mechanisms of action of the natural products, to the models on which they were investigated, and to the potential of different taxa to yield bioactive molecules capable of regulating the Wnt signaling.