Nano-assembly of ursolic acid with platinum prodrug overcomes multiple deactivation pathways in platinum-resistant ovarian cancer

A mitochondria-targeting heptamethine cyanine-chlorambucil formulated polymeric nanoparticle to potentiate native tumor chemotherapeutic efficacy

Chlorambucil (Cbl) is a DNA alkylating drug in the nitrogen mustard family, but the clinical applications of nitrogen mustard antitumor drugs are frequently limited by their poor aqueous solubility, poor cellular uptake, lack of targeting, and severe side effects. Additionally, mitochondria are the energy factories for cells, and tumor cells are more susceptible to mitochondrial dysfunction than some healthy cells, thus making mitochondria an important target for tumor therapy. As a proof-of-concept, direct delivery of Cbl to tumor cells' mitochondria will probably bring about new opportunities for the nitrogen mustard family. Furthermore, IR775 chloride is a small-molecule lipophilic cationic heptamethine cyanine dye with potential advantages of mitochondria targeting, near-infrared (NIR) fluorescence imaging, and preferential internalization towards tumor cells. Here, an amphiphilic drug conjugate was facilely prepared by covalently coupling chlorambucil with IR775 chloride and further self-assembly to form a carrier-free self-delivery theranostic system, in which the two components are both functional units aimed at theranostic improvement. The theranostic IR775-Cbl potentiated typical "1 + 1 > 2" tumor inhibition through specific accumulation in mitochondria, which triggered a remarkable decrease in mitochondrial membrane potential and ATP generation. In vivo biodistribution and kinetic monitoring were achieved by real-time NIR fluorescence imaging to observe its transport inside a living body. Current facile mitochondria-targeting modification with clinically applied drugs was promising for endowing traditional drugs with targeting, imaging, and improved potency in disease theranostics.

Self-assembled nanodrug delivery systems for anti-cancer drugs from traditional Chinese medicine

Traditional Chinese medicine (TCM) is a combination of raw herbs and herbal extracts with a plethora of documented beneficial bioactivities, which has unique advantages in anti-tumor therapy, and many of its major bioactive molecules have been identified in recent years due to advances in chemical separation and structural analysis. However, the major chemical classes of plant-derived bioactive compounds frequently possess chemical properties, including poor water solubility, stability, and bioavailability, that limit their therapeutic application. Alternatively, natural small molecules (NSMs) containing these components possess modifiable groups, multiple action sites, hydrophobic side chains, and a rigid skeleton with self-assembly properties that can be exploited to construct self-assembled nanoparticles with therapeutic effects superior to their individual constituents. For instance, the construction of a self-assembled nanodrug delivery system can effectively overcome the strong hydrophobicity and poor in vivo stability of NSMs, thereby greatly improving their bioavailability and enhancing their anti-tumor efficacy. This review summarizes the self-assembly methods, mechanisms, and applications of a variety of NSMs, including terpenoids, flavonoids, alkaloids, polyphenols, and saponins, providing a theoretical basis for the subsequent research on NSMs and the development of SANDDS.

Three-pronged attacks by hybrid nanoassemblies involving a natural product, carbon dots, and Cu2+ for synergistic HCC therapy

Tumor microenvironment (TME) stimuli-responsive nanoassemblies are emerging as promising drug delivery systems (DDSs), which acquire controlled release by structural transformation under exogenous stimulation. However, the design of smart stimuli-responsive nanoplatforms integrated with nanomaterials to achieve complete tumor ablation remains challenging. Therefore, it is of utmost importance to develop TME-based stimuli-responsive DDSs to enhance drug-targeted delivery and release at tumor sites. Herein, we proposed an appealing strategy to construct fluorescence-mediated TME stimulus-responsive nanoplatforms for synergistic cancer therapy by assembling photosensitizers (PSs) carbon dots (CDs), chemotherapeutic agent ursolic acid (UA), and copper ions (Cu2+). First, UA nanoparticles (UA NPs) were prepared by self-assembly of UA, then UA NPs were assembled with CDs via hydrogen bonding force to obtain UC NPs. After combining with Cu2+, the resulting particles (named UCCu2+ NPs) exhibited quenched fluorescence and photosensitization due to the aggregation of UC NPs. Upon entering the tumor tissue, the photodynamic therapy (PDT) and the fluorescence function of UCCu2+ were recovered in response to TME stimulation. The introduction of Cu2+ triggered the charge reversal of UCCu2+ NPs, thereby promoting lysosomal escape. Furthermore, Cu2+ resulted in additional chemodynamic therapy (CDT) capacity by reacting with hydrogen peroxide (H2O2) as well as by consuming glutathione (GSH) in cancer cells through a redox reaction, hence magnifying intracellular oxidative stress and enhancing the therapeutic efficacy due to reactive oxygen species (ROS) therapy. In summary, UCCu2+ NPs provided an unprecedented novel approach for improving the therapeutic efficacy through the three-pronged (chemotherapy, phototherapy, and heat-reinforced CDT) attacks to achieve synergistic therapy.

Platinum-based combination nanomedicines for cancer therapy

The relatively low success rate of cancer nanomedicines has raised debate on the roles of the enhanced permeability and retention (EPR) effect in enhancing drug delivery to tumors and improving therapeutic efficacy. In this review, we highlight new strategies beyond the EPR effect for enhancing nanoparticle delivery to tumors. We discuss the roles of transcellular extravasation, receptor-mediated pathways, and protein corona interactions on nanoparticle deposition in tumors. We summarize recent progress in platinum-based combination nanomedicines containing multiple chemotherapeutics with synergistic anticancer mechanisms and multiple anticancer therapies with novel mechanisms to enhance drug delivery and antitumor activities. We also highlight future opportunities in platinum-based combination nanomedicines and key hurdles for the translation of these combination nanomedicines into the clinic.

Reduction-responsive dextran-based Pt(IV) nano-prodrug showed a synergistic effect with doxorubicin for effective melanoma treatment

Melanoma, the deadliest skin cancer with high metastasis potential, has posed a great threat to human health. Accordingly, early efficient blocking of melanoma progression is vital in antitumor treatment. Herein, a reduction-responsive dextran-based Pt(IV) nano-prodrug (PDPN) was synthesized and used for doxorubicin (DOX) delivery to combat melanoma synergistically. First, PDPN was prepared by one-pot chemical coupling of carboxylated methoxy poly(ethylene glycol) (mPEG), dextran (Dex), and the crosslinking agent cisPt (IV)-COOH. PDPN had a spherical structure (R_h = 34 ± 11.3 nm). Then, DOX was encapsulated into the PDPN core to form DOX-loaded PDPN (PDPN-DOX). The obtained PDPN-DOX displayed reduction-responsive release of DOX and Pt, thus showing a synergistic anticancer effect in B16F10 cells (combination index, 0.46). Furthermore, in vivo experiments demonstrated that PDPN-DOX was effective for the synergistic treatment of subcutaneous melanoma. Collectively, the as-prepared PDPN could serve as a promising and versatile nano-prodrug carrier for the co-delivery of chemotherapeutics in tumor combination therapy.

Charge-conversional click polyprodrug nanomedicine for targeted and synergistic cancer therapy

Polyprodrug nanomedicines hold great potential for combating tumors. However, the functionalization of polyprodrug nanomedicines to improve therapeutic efficacy is restricted by conventional polymerization methods. Herein, we fabricated a charge-conversional click polyprodrug nanomedicine system by metal-free azide-alkyne cycloaddition click polymerization (AACCP) for targeted and synergistic cancer therapy. Specifically, Pt(IV) prodrug-backboned diazide monomer, DMC prodrug-pendent diazide monomer, dialkyne-terminated PEG monomer and azide-modified folate were click polymerized to obtain the target polyprodrug (P1). P1 could self-assemble into nano-micelles (1-NM), where PEG was the hydrophilic shell with folate on the surface, Pt(IV) and DMC prodrugs as the hydrophobic core. Taking advantage of PEGylation and folate-mediated tumor cell targeting, 1-NM achieved prolonged blood circulation time and high tumor accumulation efficiency. Tumor acidic microenvironment-responsive cleavage and cascade activation of pendant DMC prodrug induced surface charge conversion of 1-NM from negative to positive, which promoted tumor penetration and cellular internalization of the remaining 1-NM. After internalization into tumor cells, the reduction-responsive activation of Pt(IV) prodrug to Pt(II) further showed synergetic effect with DMC for enhanced apoptosis. This first designed charge-conversional click polyprodrug nanomedicine exhibited targeted and synergistic efficacy to suppress tumor proliferation in living mice bearing human ovarian tumor model.

Design, synthesis, and biological evaluation of new arjunolic acid derivatives as anticancer agents

Arjunolic acid (AA) is a pentacyclic triterpenoid with promising anticancer properties. A series of novel AA derivatives containing a pentameric A-ring with an enal moiety, combined with additional modifications at C-28, were designed and prepared. The biological activity on the viability of human cancer and non-tumor cell lines was evaluated in order to identify the most promising derivatives. Additionally, a preliminary study of the structure-activity relationship was carried out. The most active derivative, derivative 26, also showed the best selectivity between malignant cells and non-malignant fibroblasts. For compound 26, the anticancer molecular mechanism of action in PANC-1 cells was further studied and the results showed that this derivative induced a cell-cycle arrest at G0/G1 phase and significantly inhibited the wound closure rate of PANC-1 cancer cells in a concentration-dependent manner. Additionally, compound 26 synergistically increased the cytotoxicity of Gemcitabine, especially at a concentration of 0.24 μM. Moreover, a preliminary pharmacological study indicated that at lower doses this compound did not demonstrate toxicity in vivo. Taken together, these findings suggest that compound 26 may be a valuable compound for the development of new pancreatic anticancer treatment, and further studies are needed to explore its full potential.

The role of Platinum(IV)-based antitumor drugs and the anticancer immune response in medicinal inorganic chemistry. A systematic review from 2017 to 2022

Platinum-based antitumor drugs have been used in many types of tumors due to its broad antitumor spectrum in clinic. Encouraged by the cisplatin's (CDDP) worldwide success in cancer chemotherapy, the research in platinum-based antitumor drugs has evolved from traditional platinum drug to multi-ligand and multifunctional platinum prodrugs over half a century. With the rapid development of metal drugs and the anticancer immune response, challenges and opportunities in platinum drug research have been shifted from traditional platinum-based drugs to platinum-based hybrids and the direction of development is tending toward photodynamic therapy, nano-delivery therapy, drug combination, targeted therapy, diagnostic therapy, immune-combination therapy and tumor stem cell therapy. In this review, we first exhaustively overviewed the role of platinum-based antitumor prodrugs and the anticancer immune response in medicinal inorganic chemistry based on the special nanomaterials, the modification of specific ligands, and the multiple functions obtained that are beneficial for tumor therapy in the last five years. We also categorized them according to drug potency and function. There hasn't been a comprehensive evaluation of precursor platinum drugs in prior articles. And a multifarious approach to distinguish and detail the variety of alterations of platinum-based precursors in various valence states also hasn't been summarized. In addition, this review points out the main problems at the interface of chemistry, biology, and medicine from their action mechanisms for current platinum drug development, and provides up-to-date potential strategies from drug design perspectives to circumvent those drawbacks. And a promising idea is also enlightened for researchers in the development and discovery of platinum prodrugs.

Self-targeting platinum(IV) amphiphilic prodrug nano-assembly as radiosensitizer for synergistic and safe chemoradiotherapy of hepatocellular carcinoma

Chemoradiotherapy is a widely used treatment for patients with malignancies such as hepatocellular carcinoma (HCC). However, it remains challenging to realize safe and synergistic chemotherapy and radiation sensitization. Herein, we design a self-targeting nano-assembly (STNA) based on platinum(IV)-lactose amphiphilic prodrug for synergistic and safe chemoradiotherapy of HCC. The Pt STNA would improve the tumor accumulation due to the targeting ability of lactose to HCC cells. After receptor-mediated endocytosis, Pt STNA would release cisplatin(II) in cancer cells to form DNA-binding, thus inducing DNA damage and cell apoptosis. Meanwhile, the DNA-binding also causes cell cycle arrest in the radiation-sensitive G2/M phase by the up-regulation of phosphorylated checkpoint kinase 1 (p-Chk1) expression. Furthermore, under X-ray irradiation, Pt STNA as radiosensitizer possesses a strong X-ray attenuation ability to deposit more energy, thus elevating the level of reactive oxygen species (ROS) to amplify the cell-killing effect of radiotherapy in the G2/M phase with increased DNA damage. As a result, Pt STNA exhibits significant synergistic therapeutic effects in chemoradiotherapy with no adverse effects in vitro and in vivo. Overall, we present a novel self-targeting nano-assembly strategy based on widely used Pt drugs for synergistic chemotherapy and radiation sensitization of HCC treatment.

CuS Nanoparticles-Loaded and Cisplatin Prodrug Conjugated Fe(III)-MOFs for MRI-Guided Combination of Chemotherapy and NIR-II Photothermal Therapy

Ovarian cancer has become an urgent threat to global female healthcare. Cisplatin, as the traditional chemotherapeutic agent against ovarian cancer, retains several limitations, such as drug resistance and dose-limiting toxicity. In order to solve the above problems and promote the therapeutic effect of chemotherapy, combining chemotherapy and phototherapy has aroused wide interest. In this study, we constructed a versatile cisplatin prodrug-conjugated therapeutic platform based on ultrasmall CuS-modified Fe(III)-metal-organic frameworks (MIL-88) (named M-Pt/PEG-CuS) for tumor-specific enhanced synergistic chemo-/phototherapy. After intravenous injection, M-Pt/PEG-CuS presented obvious accumulation in tumor and Fe(III)-MOFs possessed magnetic resonance imaging (MRI) to guide synergy therapy. Both in vitro and in vivo experimental results showed that M-Pt/PEG-CuS could not only successfully inhibit tumor growth by combining chemotherapy and NIR-II PTT but also avoid the generation of liver damage by the direct treatment of cisplatin(II). Our work presented the development of the nanoplatform as a novel NIR-II photothermal agent, as well as gave a unique combined chemo-photothermal therapy strategy, which might provide new ways of ovarian cancer therapy for clinical translation.

A Fe(III)-porphyrin-oxaliplatin(IV) nanoplatform for enhanced ferroptosis and combined therapy

Since there are several limitations in cancer treatment for traditional chemotherapy, such as side effects, poor prognosis and drug resistance, developing new combined therapy is urgently needed. In this work, a biocompatible, simple and tumor microenvironment-responsive nanotheranostics (PCN-Oxpt/PEG) was built to favor the chemotherapy/ferroptosis/immunomodulation synergism in cancer. This nanotheranostics is constructed by modifying oxaliplatin prodrug and PEG on Fe(III) - porphyrin metal-organic frameworks (PCN(Fe) MOFs). After intravenous injection, the cloak of PEG leads to long circulation, and the Fe(III)-porphyrin MOFs enables dual-model guidance with fluorescence (FL) and magnetic resonance imaging (MRI). Inside the tumor, the intracellular H₂O₂ would be transferred into hydroxyl radicals (•OH) by iron ions released from MOFs, which could trigger the lethal ferroptosis to cancer cells. Meanwhile, oxaliplatin(II) transformed from the loaded oxaliplatin prodrug would result in the chemotherapy, as well as immunogenic cell death (ICD), and the prodrug strategy could also avoid the occurring of liver damage by the direct administration of oxaliplatin(II). It was noticed that the ferroptosis effect was enhanced by triple-assistance during the combined therapy, as followed: (1) glutathione (GSH) would be consumed in the process of oxaliplatin(II) generation from oxaliplatin prodrug; (2) the increased CD8⁺ T cells induced by ICD were able to produce interferon-γ (IFN-γ), which could inhibit the transport of cystine by tumor cells, and impair the activation of glutathione peroxidase 4 (GPX4); (3) the amount of H₂O₂ could be increased by the internalized oxaliplatin and thus further promote the Fenton reaction and ferroptosis. Both in vivo and in vitro results revealed that tumor growing was significantly inhibited by PCN-Oxpt/PEG, taken together, the concomitant of oxaliplatin-mediated chemotherapy and ICD with triple-enhanced ferroptosis offer great prospect in the clinical treatment of cancer.

Nano-bio interactions: A major principle in the dynamic biological processes of nano-assemblies

Controllable nano-assembly with stimuli-responsive groups is emerging as a powerful strategy to generate theranostic nanosystems that meet unique requirements in modern medicine. However, this prospective field is still in a proof-of-concept stage due to the gaps in our understanding of complex-(nano-assemblies)-complex-(biosystems) interactions. Indeed, stimuli-responsive assembly-disassembly is, in and of itself, a process of nano-bio interactions, the key steps for biological fate and functional activity of nano-assemblies. To provide a comprehensive understanding of these interactions in this review, we first propose a 4W1H principle (Where, When, What, Which and How) to delineate the relevant dynamic biological processes, behaviour and fate of nano-assemblies. We further summarize several key parameters that govern effective nano-bio interactions. The effects of these kinetic parameters on ADMET processes (absorption, distribution, metabolism, excretion and transformation) are then discussed. Furthermore, we provide an overview of the challenges facing the evaluation of nano-bio interactions of assembled nanodrugs. We finally conclude with future perspectives on safe-by-design and application-driven-design of nano-assemblies. This review will highlight the dynamic biological and physicochemical parameters of nano-bio interactions and bridge discrete concepts to build a full spectrum understanding of the biological outcomes of nano-assemblies. These principles are expected to pave the way for future development and clinical translation of precise, safe and effective nanomedicines with intelligent theranostic features.

Alantolactone-Loaded Pegylated Prodrug Nanocarriers for Synergistic Treatment of Cisplatin-Resistant Ovarian Cancer via Reactivating Mitochondrial Apoptotic Pathway

Ovarian cancer (OV) seriously damages women's health because of refractory OV and the development of platinum (Pt) resistance. New treatment strategies are urgently needed to deal with the treatment of cisplatin-resistant OV. Here, a reduction-sensitive pegylated Pt(IV) prodrug was synthesized by amidation of methoxy polyethylene glycol amine (PEG₇₅₀-NH₂) with monocarboxylic Pt(IV) prodrug (Pt(IV)-COOH). Then alantolactone (AL) loaded PEG-Pt(IV) nanocarriers (NP(Pt)@AL) were prepared. In the cisplatin-resistant model of OV, cancer cells actively ingest NP(Pt)@AL through endocytosis, and AL and Pt(II) were disintegrated and released under high intracellular reductant condition. The activity of thioredoxin reductase 1 (TrxR1) inhibited by AL and the adducts of Pt(II) with mitochondrial DNA (mDNA) can costimulate reactive oxygen species (ROS) and reactivate the mitochondrial pathway of apoptosis. Meanwhile, Pt(II) binds with nuclear DNA (nDNA) to jointly promote cell apoptosis. Both in vitro and in vivo results demonstrated that NP(Pt)@AL could effectively reverse the drug resistance and displayed excellent synergistic therapeutic efficacy on platinum-resistant OV with high safety. Therefore, reactivation of the mitochondrial pathway of apoptosis would be a potential strategy to improve the therapeutic effect of Pt-based chemotherapy and even reverse drug resistance.

Engineering CpG-ASO-Pt-loaded Macrophages (CAP@M) For Synergistic Chemo-/Gene-/Immuno-Therapy

Adoptive cell therapy by natural cells for drug delivery has achieved encouraging progress in cancer treatment over small-molecule drugs. Macrophages have a great potential in antitumor drug delivery due to their innate capability of sensing chemotactic cues and homing toward tumors. However, major challenge in current macrophage-based cell therapy is loading macrophages with adequate amounts of therapeutic, while allowing them to play a role in immunity without compromising cell functions. Herein, we demonstrate a potent strategy to construct a macrophage-mediated drug delivery platform loaded with a nanosphere (CpG-ASO-Pt) composed of functional nucleic acid therapeutic (CpG-ASO) and chemotherapeutic drug cisplatin (Pt). These CpG-ASO-Pt nanosphere loaded macrophages (CAP@M) are employed not only as carriers to deliver this nanosphere toward the tumor sites, but also simultaneously to guide the differentiation and maintain immunostimulatory effects. Both in vitro and in vivo experiments have indicated that CAP@M is a promising nanomedicine by macrophage-mediated nanospheres delivery and synergistically immunostimulatory activities. Taken together, this study provides a new strategy to construct a macrophage-based drug delivery system for synergistic chemo-/gene-/immuno-therapy. This article is protected by copyright. All rights reserved.

Metallodrugs in cancer nanomedicine

Metal complexes are extensively used for cancer therapy. The multiple variables available for tuning (metal, ligand, and metal-ligand interaction) offer unique opportunities for drug design, and have led to a vast portfolio of metallodrugs that can display a higher diversity of functions and mechanisms of action with respect to pure organic structures. Clinically approved metallodrugs, such as cisplatin, carboplatin and oxaliplatin, are used to treat many types of cancer and play prominent roles in combination regimens, including with immunotherapy. However, metallodrugs generally suffer from poor pharmacokinetics, low levels of target site accumulation, metal-mediated off-target reactivity and development of drug resistance, which can all limit their efficacy and clinical translation. Nanomedicine has arisen as a powerful tool to help overcome these shortcomings. Several nanoformulations have already significantly improved the efficacy and reduced the toxicity of (chemo-)therapeutic drugs, including some promising metallodrug-containing nanomedicines currently in clinical trials. In this critical review, we analyse the opportunities and clinical challenges of metallodrugs, and we assess the advantages and limitations of metallodrug delivery, both from a nanocarrier and from a metal-nano interaction perspective. We describe the latest and most relevant nanomedicine formulations developed for metal complexes, and we discuss how the rational combination of coordination chemistry with nanomedicine technology can assist in promoting the clinical translation of metallodrugs.

The Synergistic Reducing Drug Resistance Effect of Cisplatin and Ursolic Acid on Osteosarcoma through a Multistep Mechanism Involving Ferritinophagy

Increasing evidence suggests that traditional Chinese medicine strategies are obviously beneficial for cancer treatment, but scientific research on the underlying molecular mechanisms is lacking. We report that ursolic acid, a bioactive ingredient isolated from Radix Actinidiae chinensis, has strong antitumour effects on osteosarcoma cells. Functional studies showed that ursolic acid inhibited tumour cell proliferation and promoted the apoptosis of a variety of osteosarcoma cells. Ursolic acid had a synergistic cytotoxic effect with cisplatin on osteosarcoma cells. In a mouse osteosarcoma xenograft model, low-dose cisplatin combined with ursolic acid significantly reduced tumour growth. Notably, ursolic acid reversed weight loss in mice treated with cisplatin. Mechanistic studies showed that ursolic acid degraded ferritin by activating autophagy and induced intracellular overload of ferrous ions, leading to ferroptosis. In addition, ursolic acid enhanced the DNA-damaging effect of cisplatin on osteosarcoma cells. Taken together, these findings suggest that ursolic acid is a nontoxic adjuvant that may enhance the effectiveness of chemotherapy in osteosarcoma.

Polyethylene glycol-derived polyelectrolyte-protein nanoclusters for protein drug delivery

Polyelectrolyte-protein nanocomplexes prepared under mild and simple conditions which could have biological activity arising from protein have emerged as fascinating protein delivery systems. However, common polyelectrolytes have problems of biocompatibility and metabolism in vivo, which may limit their further applications. Herein, a novel polyethylene glycol polyelectrolyte was synthesized and used for carrying protein drugs. Different from previously reported polyelectrolyte-protein nanoclusters, the polyethylene glycol polyelectrolyte-protein nanoclusters avoid organic solvent and protein modification, and the structure and bioactivity of proteins are well preserved. Moreover, the polyethylene glycol polyelectrolyte-protein nanoclusters have good hemocompatibility and biocompatibility. These novel polyethylene glycol polyelectrolyte-protein nanoclusters would provide a potent tool for fabrication of versatile protein drug carriers.

Platinum-based chemotherapy via nanocarriers and co-delivery of multiple drugs

Platinum-based anticancer drugs can inhibit the growth of cancer cells by disrupting DNA replication, which makes them widely applicable in clinics for treating tumors and cancers. However, owing to the intrinsic or acquired drug resistance and severe side effects caused in the treatment, their successful clinical applications have been limited. Various strategies have been used to address these challenges. Nanocarriers have been used for platinum drug delivery because they can be effectively deposited in tumor tissues to reduce the damage to normal organs for an enhanced permeability and retention (EPR) effect. Furthermore, for synergizing the function of platinum-based drugs with different mechanisms to decrease the toxicities, multicomponent chemotherapy has become an imperative strategy in clinical cancer treatments. This review aims to introduce the mechanisms of action and limitations of platinum-based drugs in clinics, followed by providing the current advancement of nanocarriers including lipids, polymers, dendrimers, micelles and albumin for platinum drug delivery in cancer treatments. In addition, multicomponent chemotherapy based on platinum drugs is introduced in detail. Finally, the prospects of multicomponent chemotherapy for cancer treatment are discussed as well.