Nanoscale drug delivery platforms overcome platinum-based resistance in cancer cells due to abnormal membrane protein trafficking

Bioelectrocatalytic Activity of One-Dimensional Porous Pt Nanoribbons for Efficient Inhibition of Tumor Growth and Metastasis

Designing and synthesizing one-dimensional porous Pt nanocrystals with unique optical, electrocatalytic, and theranostic properties are gaining lots of attention, especially to overcome the challenges of tumor recurrence and resistance to platinum-based chemotherapy. Herein, we represented an interesting report of a one-step and facile strategy for synthesizing multifunctional one-dimensional (1D) porous Pt nanoribbons (PtNRBs) with highly efficient therapeutic effects on cancer cells based on inherent electrocatalytic activity. The critical point in the formation of luminescent porous PtNRBs was the use of human hemoglobin (Hb) as a shape-regulating, stabilizing, and reducing agent with facet-specific domains on which fluorescent platinum nanoclusters at first are aggregated by aggregation-induced emission phenomena (AIE) and then crystallized into contact and penetration twins, as intermediate products, followed by shaping of the final luminescent porous ribbon nanomaterials, owing to oriented attachment association via the Ostwald ripening mechanism. From a medical point of view, the key strategy for effective cancer therapy occured via using low-dosage ethanol in the presence of electroactive porous PtNRBs based on intracellular ethanol oxidation-mediated reactive oxygen species (ROS) generation. The role of heme groups of Hb, as electrocatalytically active centers, was successfully demonstrated in both kinetically controlled anisotropic growth of NRBs for slowing down the reduction of Pt(II) followed by oligomerization of Pt(II)-Hb complexes via platinophilic interactions as well as electrocatalytic ethanol oxidation for therapy. Interestingly, hyaluronic acid-targeted (HA) Hb-PtNRB in the presence of low-dose ethanol caused extraordinary arrest of tumor growth and metastasis with no recurrence even after the treatment course stopped, which caused elongation of tumor-bearing mice survival. HA/Hb-PtNRB was completely biocompatible and exhibited high tumor-targeting efficacy for fluorescent imaging of breast tumors. Therefore, the synergistic electrocatalytic activity of PtNRBs is presented as an efficient and safe cancer theranostic method for the first time.

Stability-Enhanced Cisplatin Gold Nanoparticles As Therapeutic Anticancer Agents

Using dendron chemistry, we developed stability enhanced, carboxylate surface modified (negatively charged dendron) AuNPs (Au-NCD). Since the carboxylate surface of Au-NCD is optimal for complexation with cisplatin (Pt) moieties, we further synthesized Pt loaded Au-NCD (Au-NCD/Pt) to serve as potential therapeutic anticancer agents. The size distribution, zeta potential and surface plasmon resonance of both Au-NCDs and Au-NCD/Pt were characterized via dynamic light scattering, scanning transmission electron microscopy and ultraviolet-visible spectrophotometry. Surface chemistry, Pt uptake, and Pt release were evaluated using inductively coupled plasma-mass spectrometry and X-ray photoelectron spectroscopy. Colloidal stability in physiological media over a wide pH range (1 to 13) and shelf-life stability (up to 6 months) were also assessed. Finally, the cytotoxicity of both Au-NCD and Au-NCD/Pt to Chinese hamster ovary cells (CHO K1; as a normal cell line) and to human lung epithelial cells (A549; as a cancer cell line) were evaluated. The results of these physicochemical and functional cytotoxicity studies with Au-NCD/Pt demonstrated that the particles exhibited superlative colloidal stability, cisplatin uptake and in vitro anticancer activity despite low amounts of Pt release from the conjugate.

Anticancer Activity of Nonpolar Pt(CH3)2I2{bipy} is Found to be Superior among Four Similar Organoplatinum(IV) Complexes

The anticancer properties of well-defined molecules serve to bolster the field of metals in medicine. Such compounds, particularly those of platinum and their closely related structural analogs, continue to be potentially highly interesting to researchers and clinicians alike. The four octahedral organoplatinum(IV) compounds [Pt(CH3)2X2{bipy-R 2 }] (X = Br, I; bipy-R 2 = 2,2'-bipyridine, 2,2'-bipyridine-4,4'-dicarboxylic acid) have been isolated and structurally characterized by single-crystal X-ray diffraction. Nuclear magnetic resonance and infrared spectroscopic data are also tabulated as useful reference values. The anticancer potential of each compound was assessed via in vitro MTT assays, using human breast cancer cells (cell line ZR-75-1). EC50 values were determined as 11.5 μM for Pt(CH3)2Br2{bipy}; 3020 μM, for Pt(CH3)2Br2{bipy-(CO 2 H) 2 }; 6.1 μM, for Pt(CH3)2I2{bipy}; and 86.0 μM, for Pt(CH3)2I2{bipy-(CO 2 H) 2 }; for comparison, the EC50 value for cisplatin against the ZR-75-1 cells was 16.4 μM. The most cytotoxic of the four compounds Pt(CH3)2I2{bipy} undergoes reaction with glutathione in a THF/water mixture at 68°C very slowly.

A Recent Advancement in Nanotechnology Approaches for the Treatment of Cervical Cancer

BACKGROUND

Cervical cancer is one of the leading causes of female death, with a mortality rate of over 200,000 per year in developing countries. Despite a decrease in cervical cancer occurrences in developed countries over the last decade, the frequency of the disease in developing nations continues to rise at an alarming rate, particularly when it is linked to the human papillomavirus (HPV). With just a few highly invasive conventional therapies available, there is a clear need for novel treatment options such as nanotechnology-based chemotherapeutic drug delivery.

METHODS

Traditional anticancer therapy is limited by poor drug potency, non-specificity, unwanted side effects, and the development of multiple drug resistance (MDR), leading to a decrease in long-term anticancer therapeutic efficacy. An ideal cancer therapy requires a personalized and specialized medication delivery method capable of eradicating even the last cancer cell responsible for disease recurrence.

RESULTS

Nanotechnology provides effective drug delivery mechanisms, allowing it to serve both therapeutic and diagnostic purposes. Nanotechnology-based formulations are widely used to accurately target the target organ, maintain drug load bioactivity, preferentially accumulate the drug at the target location, and reduce cytotoxicity.

CONCLUSION

The key benefits of this drug delivery are that it improves pharmacological activity, solubility, and bioavailability and reduces toxicity in the target tissue by targeting ligands, allowing for new innovative treatment methods in an area that is desperately required. The goal of this review is to highlight possible research on nanotechnologybased delivery systems for cancer detection and treatment.

Cytotoxic sub-nanometer aqueous platinum clusters as potential antitumoral agents

Ligand-free sub-nanometer metal clusters (MCs) of Pt, Ir, Rh, Au and Cu, are prepared here in neat water and used as extremely active (nM) antitumoral agents for HeLa and A2870 cells. The preparation just consists of adding the biocompatible polymer ethylene-vinyl alcohol (EVOH) to an aqueous solution of the corresponding metal salt, to give liters of a MC solution after filtration of the polymer. Since the MC solution is composed of just neat metal atoms and water, the intrinsic antitumoral activity of the different sub-nanometer metal clusters can now fairly be evaluated. Pt clusters show an IC50 of 0.48 μM for HeLa and A2870 cancer cells, 23 times higher than that of cisplatin and 1000 times higher than that of Pt NPs, and this extremely high cytotoxicity also occurs for cisplatin-resistant (A2870 cis) cells, with a resistance factor of 1.4 (IC50 = 0.68 μM). Rh and Ir clusters showed an IC50 ∼ 1 μM. Combined experimental and computational studies support an enhanced internalization and cytotoxic activation.

Multifunctional Nanoplatforms as a Novel Effective Approach in Photodynamic Therapy and Chemotherapy, to Overcome Multidrug Resistance in Cancer

It is more than sixty years since the era of modern photodynamic therapy (PDT) for cancer began. Enhanced selectivity for malignant cells with a reduced selectivity for non-malignant cells and good biocompatibility along with the limited occurrence of side effects are considered to be the most significant advantages of PDT in comparison with conventional therapeutic approaches, e.g., chemotherapy. The phenomenon of multidrug resistance, which is associated with drug efflux transporters, was originally identified in relation to the application of chemotherapy. Unfortunately, over the last thirty years, numerous papers have shown that many photosensitizers are the substrates of efflux transporters, significantly restricting the effectiveness of PDT. The concept of a dynamic nanoplatform offers a possible solution to minimize the multidrug resistance effect in cells affected by PDT. Indeed, recent findings have shown that the utilization of nanoparticles could significantly enhance the therapeutic efficacy of PDT. Additionally, multifunctional nanoplatforms could induce the synergistic effect of combined treatment regimens, such as PDT with chemotherapy. Moreover, the surface modifications that are associated with nanoparticle functionalization significantly improve the target potential of PDT or chemo-PDT in multidrug resistant and cancer stem cells.

Update on the Use of Nanocarriers and Drug Delivery Systems and Future Directions in Cervical Cancer

Cervical cancer represents a major health problem among females due to its increased mortality rate. The conventional therapies are very aggressive and unsatisfactory when it comes to survival rate, especially in terminal stages, which requires the development of new treatment alternatives. With the use of nanotechnology, various chemotherapeutic drugs can be transported via nanocarriers directly to cervical cancerous cells, thus skipping the hepatic first-pass effect and decreasing the rate of chemotherapy side effects. This review comprises various drug delivery systems that were applied in cervical cancer, such as lipid-based nanocarriers, polymeric and dendrimeric nanoparticles, carbon-based nanoparticles, metallic nanoparticles, inorganic nanoparticles, micellar nanocarriers, and protein and polysaccharide nanoparticles. Nanoparticles have a great therapeutic potential by increasing the pharmacological activity, drug solubility, and bioavailability. Through their mechanisms, they highly increase the toxicity in the targeted cervical tumor cells or tissues by linking to specific ligands. In addition, a nondifferentiable model is proposed through holographic implementation in the dynamics of drug delivery dynamics. As any hologram functions as a deep learning process, the artificial intelligence can be proposed as a new analyzing method in cervical cancer.

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.

Lipid, polymeric, inorganic-based drug delivery applications for platinum-based anticancer drugs

The three main FDA-approved platinum drugs in chemotherapy such as carboplatin, cisplatin, and oxaliplatin are extensively applied in cancer treatments. Although the clinical applications of platinum-based drugs are extremely effective, their toxicity profile restricts their extensive application. Therefore, recent studies focus on developing new platinum drug formulations, expanding the therapeutic aspect. In this sense, recent advances in the development of novel drug delivery carriers will help with the increase of drug stability and biodisponibility, concomitantly with the reduction of drug efflux and undesirable secondary toxic effects of platinum compounds. The present review describes the state of the art of platinum drugs with their biological effects, pre- and clinical studies, and novel drug delivery nanodevices based on lipids, polymers, and inorganic.

Elucidating Role of Reactive Oxygen Species (ROS) in Cisplatin Chemotherapy: A Focus on Molecular Pathways and Possible Therapeutic Strategies

The failure of chemotherapy is a major challenge nowadays, and in order to ensure effective treatment of cancer patients, it is of great importance to reveal the molecular pathways and mechanisms involved in chemoresistance. Cisplatin (CP) is a platinum-containing drug with anti-tumor activity against different cancers in both pre-clinical and clinical studies. However, drug resistance has restricted its potential in the treatment of cancer patients. CP can promote levels of free radicals, particularly reactive oxygen species (ROS) to induce cell death. Due to the double-edged sword role of ROS in cancer as a pro-survival or pro-death mechanism, ROS can result in CP resistance. In the present review, association of ROS with CP sensitivity/resistance is discussed, and in particular, how molecular pathways, both upstream and downstream targets, can affect the response of cancer cells to CP chemotherapy. Furthermore, anti-tumor compounds, such as curcumin, emodin, chloroquine that regulate ROS and related molecular pathways in increasing CP sensitivity are described. Nanoparticles can provide co-delivery of CP with anti-tumor agents and by mediating photodynamic therapy, and induce ROS overgeneration to trigger CP sensitivity. Genetic tools, such as small interfering RNA (siRNA) can down-regulate molecular pathways such as HIF-1α and Nrf2 to promote ROS levels, leading to CP sensitivity. Considering the relationship between ROS and CP chemotherapy, and translating these findings to clinic can pave the way for effective treatment of cancer patients.

Cyclodextrin-Based Hybrid Polymeric Complex to Overcome Dual Drug Resistance Mechanisms for Cancer Therapy

Drug resistance always reduces the efficacy of chemotherapy, and the classical mechanisms of drug resistance include drug pump efflux and anti-apoptosis mediators-mediated non-pump resistance. In addition, the amphiphilic polymeric micelles with good biocompatibility and high stability have been proven to deliver the drug molecules inside the cavity into the cell membrane regardless of the efflux of the cell membrane pump. We designed a cyclodextrin (CD)-based polymeric complex to deliver chemotherapeutic doxorubicin (DOX) and Nur77ΔDBD gene for combating pumps and non-pump resistance simultaneously. The natural cavity structure of the polymeric complex, which was comprised with β-cyclodextrin-graft-(poly(ε-caprolactone)-adamantly (β-CD-PCL-AD) and β-cyclodextrin-graft-(poly(ε-caprolactone)-poly(2-(dimethylamino) ethyl methacrylate) (β-CD-PCL-PDMAEMA), can achieve the efficient drug loading and delivery to overcome pump drug resistance. The excellent Nur77ΔDBD gene delivery can reverse Bcl-2 from the tumor protector to killer for inhibiting non-pump resistance. The presence of terminal adamantyl (AD) could insert into the cavity of β-CD-PCL-PDMAEMA via host-guest interaction, and the releasing rate of polymeric inclusion complex was higher than that of the individual β-CD-PCL-PDMAEMA. The polymeric inclusion complex can efficiently deliver the Nur77ΔDBD gene than polyethylenimine (PEI-25k), which is a golden standard for nonviral vector gene delivery. The higher transfection efficacy, rapid DOX cellular uptake, and significant synergetic tumor cell viability inhibition were achieved in a pump and non-pump drug resistance cell model. The combined strategy with dual drug resistance mechanisms holds great potential to combat drug-resistant cancer.

Multifunctional tumor-targeted PLGA nanoparticles delivering Pt(IV)/siBIRC5 for US/MRI imaging and overcoming ovarian cancer resistance

Cisplatin (Pt(II)) resistance is an important factor in the high mortality rates of ovarian cancer. Herein, we synthesized multifunctional tumor-targeted poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs-cRGD) for monitoring therapeutic effects by dual-mode imaging and overcoming cisplatin resistance. Uniformly sized NPs-cRGD demonstrated controlled and sustained release of drugs and genes, excellent gene loading and gene protection capacity, good storage stability and no serum-induced aggregation in vitro. NPs-cRGD demonstrated clear, targeting and prolonged ultrasound imaging and magnetic resonance imaging (MRI) in vivo. The targeting of NPs-cRGD combined with ultrasound facilitated nanoparticle penetrattion into cells; entry was time-dependent. NPs-cRGD escaped from lysosomes, thereby preventing siBIRC5 degradation, which enabled siBIRC5 to efficiently inhibit the antiapoptosis effects of BIRC5 in SKO3-DDP to overcome the antiapoptosis properties of resistant cells. Furthermore, Pt(IV) in NPs-cRGD exhausted glutathione (GSH), thereby increasing drug accumulation to effectively increase Pt(II) levels. The subsequent combination of Pt(II) with DNA prevented the expressions of genes and upregulated the expression of p53 to induce the mitochondria apoptosis pathway. The reduced GSH activity and the generation of Pt(II) further promoted high levels of reactive oxygen species (ROS) to induce cell apoptosis. Therefore, NPs-cRGD with ultrasound promoted the apoptosis of resistant ovarian cancer cells by multiple mechanisms, including increased cellular drug accumulation, reversed antiapoptotic effects by siBIRC5, and enhanced ROS levels. In a tumor-bearing nude mice model, NPs-cRGD with US demonstrated excellent tumor-targeting, high efficiency tumor inhibition and low systemic toxicity. Therefore, NPs-cRGD provides a means to monitor treatment processes and can be combined with ultrasound treatment to overcome ovarian cancer resistance in vitro and in vivo.

Membrane Trafficking and Subcellular Drug Targeting Pathways

The movement of micro and macro molecules into and within a cell significantly governs several of their pharmacokinetic and pharmacodynamic parameters, thus regulating the cellular response to exogenous and endogenous stimuli. Trafficking of various pharmacological agents and other bioactive molecules throughout and within the cell is necessary for the fidelity of the cells but has been poorly investigated. Novel strategies against cancer and microbial infections need a deeper understanding of membrane as well as subcellular trafficking pathways and essentially regulate several aspects of the initiation and spread of anti-microbial and anti-cancer drug resistance. Furthermore, in order to avail the maximum possible bioavailability and therapeutic efficacy and to restrict the unwanted toxicity of pharmacological bioactives, these sometimes need to be functionalized with targeting ligands to regulate the subcellular trafficking and to enhance the localization. In the recent past the scenario drug targeting has primarily focused on targeting tissue components and cell vicinities, however, it is the membranous and subcellular trafficking system that directs the molecules to plausible locations. The effectiveness of the delivery platforms largely depends on their physicochemical nature, intracellular barriers, and biodistribution of the drugs, pharmacokinetics and pharmacodynamic paradigms. Most subcellular organelles possess some peculiar characteristics by which membranous and subcellular targeting can be manipulated, such as negative transmembrane potential in mitochondria, intraluminal delta pH in a lysosome, and many others. Many specialized methods, which positively promote the subcellular targeting and restrict the off-targeting of the bioactive molecules, exist. Recent advancements in designing the carrier molecules enable the handling of membrane trafficking to facilitate the delivery of active compounds to subcellular localizations. This review aims to cover membrane trafficking pathways which promote the delivery of the active molecule in to the subcellular locations, the associated pathways of the subcellular drug delivery system, and the role of the carrier system in drug delivery techniques.

Design of a Novel Theranostic Nanomedicine (III): Synthesis and Physicochemical Properties of Tumor-Targeting Cisplatin Conjugated to a Hydrophilic Polyphosphazene

Purpose

A new theranostic nanomedicine involving anticancer-active cisplatin moiety was designed to study its tumor-targeting properties as well as its drug efficacy and toxicity.

Methods

A cisplatin carrier polymer was prepared by grafting equimolar polyethylene glycol of a molecular weight of 550 (PEG550) and aminoethanol to the poly(dichlorophosphazene) backbone. Cisplatin was conjugated to the carrier polymer using cis-aconitic acid as a linker.

Results

The cisplatin-loaded polyphosphazene, named "Polycisplatin" was found to be amphiphilic in aqueous solution and self-assembled into nanoparticles with an average particle size of 18.6 nm in diameter. The time-dependent organ distribution study of Cy5.5-labeled Polycisplatin in the A549-tumor-bearing mice exhibited a high tumor selectivity of Polycisplatin by EPR effect despite the relatively small particle size. In order to compare the in vivo efficacy of Polycisplatin and cisplatin, their xenograft trials were performed using nude mice against the human gastric cell line MKN-28. Polycisplatin exhibited slightly less tumor suppression effect compared with cisplatin at the same dose of 1.95 mg Pt/kg, which is the maximum tolerate dose of cisplatin, but at the higher double dose of 3.9 mg Pt/kg, Polycisplatin exhibited a little better efficacy than cisplatin. Furthermore, mice treated with cisplatin at the dose of 1.95 mg Pt/kg exhibited severe body weight decrease by about 25%, while mice treated with Polycisplatin did not show serious body weight decrease even at its double dose of 3.9 mg Pt/kg. Furthermore, kidney indicators including kidney index, BUN, and creatinine values measured displayed that Polycisplatin is much less nephrotoxic than cisplatin.

Conclusion

Nanoparticular Polycisplatin was successfully prepared by conjugating cisplatin to a hydrophilic polyphosphazene carrier polymer using the acid-cleavable cis-aconitic acid. Polycisplatin nanoparticles exhibit excellent tumor-targeting properties by EPR effect. The xenograft trials exhibited excellent antitumor efficacy and reduced systemic toxicity of Polycisplatin.

MWCNT-mediated combinatorial photothermal ablation and chemo-immunotherapy strategy for the treatment of melanoma

DOX and CpG loaded MWCNT with NIR irradiation could destroy tumor cells by photothermal and chemotherapy and release tumor-associated antigens, thus generating melanoma specific immune response to achieve synergistic therapeutic effect.

Antitumor Activity of Cyclodextrin-based Supramolecular Platinum Prodrug In vitro and In vivo

Background:

Considering the limitations of cisplatin in clinical application, there is ongoing research to fabricate new platinum-containing prodrug which are highly effective to tumor cells and have low toxicity to normal cells.

Methods:

In this study, a cyclodextrin-based supramolecular platinum prodrug that is 6,6’-ophenylenediseleno- bridged bis (β-cyclodextrin)s (CD) and its potassium tetrachloroplatinate(II) complex was reported. The cytotoxicity experiments were performed to evaluate the anticancer activities of supramolecular prodrug in vitro by means of MTT assay. The practical application of supramolecular prodrug in tumor treatment in vivo were evaluated using BALB/c nude mice model bearing Hela cancer cells.

Results:

Compared with commercial anticancer drug cisplatin, the resultant cyclodextrin-based platinum prodrug exhibited comparative anticancer effect but with much lower toxicity side effects in vitro and in vivo.

Conclusion:

The cyclodextrin-based supramolecular platinum prodrug displayed antitumor activity comparable to the commercial antitumor drug cisplatin but with lower side effects both in vitro and in vivo, implying that the two adjacent cyclodextrin cavities not merely act as desired solubilizer, but also endowed the prodrug with cell permeability through the interaction of cyclodextrin with phospholipids and cholesterol on cell membrane.

Computational and biological investigation of the soybean lecithin-gallic acid complex for ameliorating alcoholic liver disease in mice with iron overload

Alcoholic liver disease (ALD) is associated with significant morbidity and mortality globally. In this study, the soybean lecithin-gallic acid complex was synthesized, and its physicochemical properties were evaluated, which confirmed the complex formation. Compared with the free state of the drug, gallic acid exhibited significantly different physicochemical properties after it was complexed with soybean lecithin. To clarify the binding mode between two monomers, computational investigation was performed. From the computational data, we deduced the structure of the compound and predicted that it has a high affinity for human phosphatidylcholine transfer protein and exhibits strong pharmacological activities in vivo. The complex not only effectively ameliorated liver fibrosis, lipid peroxidation, and oxidative stress, but also reduced liver iron overload in a mouse ALD model induced by alcohol (p < 0.05). Additionally, it regulated iron metabolism by inhibiting TfR1 expression (p < 0.05) and promoting hepcidin expression (p < 0.05). These results suggest that the soybean lecithin-gallic acid complex ameliorates hepatic damage and iron overload induced by alcohol and exert hepatoprotective effects.

Thermal-Responsive Carbon Monoxide (CO) Delivery Expedites Metabolic Exhaustion of Cancer Cells toward Reversal of Chemotherapy Resistance

Multidrug resistance (MDR) is the main cause of chemotherapy failure, and the mechanism of MDR is largely associated with drug efflux mediated by the adenosine triphosphate (ATP)-binding cassette transporters. Herein, an NIR-light-triggered CO release system based on mesoporous Prussian blue nanoparticles (PB NPs) was developed to reverse MDR via CO-induced metabolic exhaustion. Pentacarbonyl iron (Fe(CO)₅) as the CO producer was coupled to PB NPs via coordination interaction, and doxorubicin (Dox) was encapsulated into the pores of PB NPs. After layer-by-layer (LBL) coating, the NPs showed desired serum stability to enhance tumor accumulation. Upon tumor-site-specific NIR light (808 nm) irradiation, the nonlethal temperature elevation cleaved the Fe-CO bond to release CO. CO then expedited mitochondrial metabolic exhaustion to block ATP synthesis and inhibit ATP-dependent drug efflux, thus reversing MDR of the Dox-resistant MCF-7/ADR tumors to potentiate the anticancer efficacy of Dox. In the meantime, CO-mediated mitochondrial exhaustion could upregulate the proapoptotic protein, caspase 3, thus inducing cellular apoptosis and enabling a synergistic anticancer effect with chemotherapy. To the best of our knowledge, this is the first time MDR has been overcome using a CO delivery system. This study provides a promising strategy to realize an effective and safe treatment against MDR tumors and reveals new insights in the use of CO for cancer treatment.

pH- and photothermal-driven multistage delivery nanoplatform for overcoming cancer drug resistance

Reversing multidrug resistance (MDR) remains a big challenge in cancer therapy. Combining the hyperthermia and chemotherapy is a promising strategy for efficient cancer treatment with MDR reversal. Gold nanocages (GNCs) are an ideal photothermal (PTT)-chemotherapy integration platform due to their good photothermal conversion efficiency and the unique hollow interiors. However, insufficient tumor cell internalization and in vivo premature drug leakage restrict the anticancer activity of GNCs-based drug delivery systems. Methods: pH low insertion peptide (pHLIP)- and thermoresponsive poly(di(ethylene glycol) methyl ether methacrylate-co-oligo(ethylene glycol) methyl ether methacrylate) polymer-conjugated GNCs were rationally constructed to load anticancer drug doxorubicin (DOX@pPGNCs). Tumor acidic environment-responsive tumor cell internalization, and near-infrared (NIR) laser-induced tumor accumulation, penetration and on-demand drug release were systematically examined. Results: DOX@pPGNCs display good photothermal efficacy and thermoresponsive property. NIR laser irradiations at the tumor site significantly enhance tumor accumulation and penetration. Once DOX@pPGNCs reach the tumor site, the conformational transformation of pHLIP at the acidic tumor microenvironment contributes to the enhanced cellular internalization. Furthermore, NIR laser-triggered photothermal effects induce the shrinkage of thermoresponsive polymer, resulting in the opening of the pores of GNCs and a rapid intracellular DOX release to the nuclei. DOX@pPGNCs exhibit synergistic antitumor effect with MDR reversal in vitro and in vivo. Conclusion: DOX@pPGNCs present strong potential to overcome MDR in cancer.

Rethinking Alkylating(-Like) Agents for Solid Tumor Management

Although old molecules, alkylating agents and platinum derivatives are still widely used in the treatment of various solid tumors. However, systemic toxicity and cellular resistance mechanisms impede their efficacy. Innovative strategies, including local administration, optimization of treatment schedule/dosage, synergistic combinations, and the encapsulation of bioactive molecules in smart, multifunctional drug delivery systems, have shown promising results in potentiating anticancer activity while circumventing such hurdles. Furthermore, questioning of the old paradigm according to which nuclear DNA is the critical target of their anticancer activity has shed light on subcellular alternative and neglected targets that obviously participate in the mediation of cytotoxicity or resistance. Thus, rethinking of the use of these pivotal antineoplastic agents appears critical to improve clinical outcomes in the management of solid tumors.

Intracellular glutathione-depleting polymeric micelles for cisplatin prodrug delivery to overcome cisplatin resistance of cancers

The intrinsic or acquired cisplatin resistance of cancer cells frequently limits the final therapeutic efficacy. Detoxification by the high level of intracellular glutathione (GSH) plays critical roles in the majority of cisplatin-resistant cancers. In this report, we designed an amphiphilic diblock copolymer composed of poly(ethylene glycol) (PEG) and polymerized phenylboronic ester-functionalized methacrylate (PBEMA), PEG-b-PBEMA, which can self-assemble into micelles in aqueous solutions to load hydrophobic cisplatin prodrug (Pt(IV)). Pt(IV)-loaded PEG-b-PBEMA micelles (PtBE-Micelle) reverse cisplatin-resistance of cancer cells through improving cellular uptake efficiency and reducing intracellular GSH level. We found that the cellular uptake amount of platinum from PtBE-Micelle was 6.1 times higher than that of free cisplatin in cisplatin-resistant human lung cancer cells (A549R). Meanwhile, GSH concentration of A549R cells was decreased to 32% upon treatment by PEG-b-PBEMA micelle at the phenyl borate-equivalent concentration of 100μM. PtBE-Micelle displayed significantly higher cytotoxicity toward A549R cells with half maximal inhibitory concentration (IC₅₀) of cisplatin-equivalent 0.20μM compared with free cisplatin of 33.15μM and Pt(IV)-loaded PEG-b-poly(ε-caprolactone) micelles of cisplatin-equivalent 0.75μM. PtBE-Micelle can inhibit the growth of A549R xenograft tumors effectively. Accordingly, PEG-b-PBEMA micelles show great potentials as drug delivery nanocarriers for platinum-based chemotherapy toward cisplatin-resistant cancers.

Unraveling the molecular mechanism of photosynthetic toxicity of highly fluorescent silver nanoclusters to Scenedesmus obliquus

While the discovery of numerous attractive properties of silver at the nanoscale has increased their demand in many sectors including medicine, optics, sensing, painting and cosmetics, it has also raised wide public concerns about their effect on living organisms in aquatic environment. Despite the continuous effort to understand the various aspects of the toxicity of silver nanomaterials, the molecular level understanding on their cytotoxicity mechanism to biological organisms has remained unclear. Herein, we demonstrated the underlying mechanism of the photosynthetic toxicity against green algae namely, Scenedesmus obliquus by using an emerging silver nanomaterial, called silver nanoclusters (defined as r-Ag NCs). By exploiting the unique fluorescence properties of r-Ag NCs along with various other analytical/biological tools, we proposed that the photosynthetic toxicity of r-Ag NCs was largely attributed to the "joint-toxicity" effect of particulate form of r-Ag NCs and its released Ag+, which resulted in the disruption of the electron transport chain of light reaction and affected the content of key enzymes (RuBP carboxylase/ oxygenase) of Calvin cycle of algae cells. We believe that the present study can also be applied to the assessment of the ecological risk derived from other metal nanoparticles.

Phosphatase-triggered cell-selective release of a Pt(iv)-backboned prodrug-like polymer for an improved therapeutic index

A Pt(iv)-backboned prodrug-like polymer was synthesized and formulated to a phosphatase-responsive polyion complex for cell-selective delivery.

Dual aptamer modified dendrigraft poly-l-lysine nanoparticles for overcoming multi-drug resistance through mitochondrial targeting

Dox/Mito-DGL could selectively unload the encapsulated Dox/duplex and induce dissociation of the DNA duplex upon the high levels of ATP in mitochondria, which thereby causes a rapid release of Dox. The strategy could significantly enhance the anticancer efficacy of the drug.

Well-defined podophyllotoxin polyprodrug brushes: preparation via RAFT polymerization and evaluation as drug carriers

Novel poly(triethylene glycol methacrylate)-b-poly(podophyllotoxin methacrylate) copolymers (PTP) with a well-defined structure were designed and synthesized by direct RAFT polymerization with the hydrophobic monomer derivative from the anticancer drug podophyllotoxin.

pH-Sensitive Pt Nanocluster Assembly Overcomes Cisplatin Resistance and Heterogeneous Stemness of Hepatocellular Carcinoma

Response rates to conventional chemotherapeutics remain unsatisfactory for hepatocellular carcinoma (HCC) due to the high rates of chemoresistance and recurrence. Tumor-initiating cancer stem-like cells (CSLCs) are refractory to chemotherapy, and their enrichment leads to subsequent development of chemoresistance and recurrence. To overcome the chemoresistance and stemness in HCC, we synthesized a Pt nanocluster assembly (Pt-NA) composed of assembled Pt nanoclusters incorporating a pH-sensitive polymer and HCC-targeting peptide. Pt-NA is latent in peripheral blood, readily targets disseminated HCC CSLCs, and disassembles into small Pt nanoclusters in acidic subcellular compartments, eventually inducing damage to DNA. Furthermore, treatment with Pt-NA downregulates a multitude of genes that are vital for the proliferation of HCC. Importantly, CD24+ side population (SP) CSLCs that are resistant to cisplatin are sensitive to Pt-NA, demonstrating the immense potential of Pt-NA for treating chemoresistant HCC.

Synthesis, characterization and in vivo evaluation of a magnetic cisplatin delivery nanosystem based on PMAA-graft-PEG copolymers

The development of anticancer drug delivery systems which retain or enhance the cytotoxic properties of the drug to tumorous tissues, while reducing toxicity to other organs is of key importance. We investigated different poly(methacrylic acid)-g-poly(ethyleneglycol methacrylate) polymers as in situ coating agents for magnetite nanocrystallites. The obtained magnetic nano-assemblies were in turn thoroughly characterized for their structural, colloidal and physicochemical properties (drug loading capacity/release, magnetic field triggered drug release, cell uptake and localization) in order to select the best performing system. With the focus on in vivo validation of such magnetic drug delivery systems for first time, we selected cisplatin as the drug, since it is a potent anticancer agent which exhibits serious side effects due to lack of selectivity. In addition, cisplatin would offer facile determination of the metal content in the animal tissues for biodistribution studies. Alongside post-mortem Pt determination in the tissues, the biodistribution of the drug nanocarriers was also monitored in real time with PET-CT (positron emission tomography/computed tomography) with and without the presence of magnetic field gradients; using a novel chelator-free method, the nanoparticles were radiolabeled with ⁶⁸Ga without having to alter their structure with chemical modifications for conjugation of radiochelators. The ability to be radiolabeled in such a straightforward but very robust way, along with their measured high MRI response, renders them attractive for dual imaging, which is an important functionality for translational investigations. Their anticancer properties were evaluated in vitro and in vivo, in a cisplatin resistant HT-29 human colon adenocarcinoma model, with and without the presence of magnetic field gradients. Enhanced anticancer efficacy and reduced toxicity was recorded for the cisplatin-loaded nanocarriers in comparison to the free cisplatin, particularly when a magnetic field gradient was applied at the tumor site. Post mortem and real-time tissue distribution studies did not reveal increased cisplatin concentration in the tumor site, suggesting that the enhanced anticancer efficacy of the cisplatin-loaded nanocarriers is driven by mechanisms other than increased cisplatin accumulation in the tumors.

Exploiting developments in nanotechnology for the preferential delivery of platinum-based anti-cancer agents to tumours: targeting some of the hallmarks of cancer

Platinum drugs as anti-cancer therapeutics are held in extremely high regard. Despite their success, there are drawbacks associated with their use; their dose-limiting toxicity, their limited activity against an array of common cancers and patient resistance to Pt-based therapeutic regimes. Current investigations in medicinal inorganic chemistry strive to offset these shortcomings through selective targeting of Pt drugs and/or the development of Pt drugs with new or multiple modes of action. A comprehensive overview showcasing how liposomes, nanocapsules, polymers, dendrimers, nanoparticles and nanotubes may be employed as vehicles to selectively deliver cytotoxic Pt payloads to tumour cells is provided.

Co-Delivery of Cisplatin Prodrug and Chlorin e6 by Mesoporous Silica Nanoparticles for Chemo-Photodynamic Combination Therapy to Combat Drug Resistance

Combination therapy shows great promise in circumventing cisplatin resistance. We report herein the development of a novel nanoscale drug delivery system (nDDS) based nanotherapeutic that combines chemotherapy and photodynamic therapy (PDT) into one single platform to achieve synergistic anticancer capacity to conquer cisplatin resistance. Mesoporous silica nanoparticle (MSNs) was used as the drug delivery vector to conjugate cisplatin prodrug and to load photosensitizer chlorin e6 (Ce6) to afford the dual drug loaded delivery system MSNs/Ce6/Pt. The hybrid nanoparticles have an average diameter of about 100 nm and slightly positive surface charge of about 18.2 mV. The MSNs/Ce6/Pt nanoparticles can be efficiently internalized by cells through endocytosis, thereby achieving much higher cellular Pt uptake than cisplatin in cisplatin-resistant A549R lung cancer cells. After 660 nm light irradiation (10 mW/cm(2)), the cellular reactive oxygen species (ROS) level in MSNs/Ce6/Pt treated cells was elevated dramatically. As a result of these properties, MSNs/Ce6/Pt exhibited very potent anticancer activity against A549R cells, giving a half-maximal inhibitory concentration (IC50) value for the combination therapy of 0.53 μM, much lower than that of cisplatin (25.1 μM). This study suggests the great potential of nDDS-based nanotherapeutic for combined chemo-photodynamic therapy to circumvent cisplatin resistance.

Shirazi F. FTIR Biospectroscopy Investigation on Cisplatin Cytotoxicity in Three Pairs of Sensitive and Resistant Cell Line

Fourier Transformed Infrared Spectroscopy (FTIR) has extensively been used for biological applications. Cisplatin is one the most useful antineoplastic chemotherapy drugs for a variety of different human cancers. One of the clinical problems in its application, which would consequently affect the therapeutic outcome of its application, is the occurrence of resistance to this agent. In this project three different pairs of sensitive and resistant cell lines of human ovarian A2780 and its resistant pair of A2780-CP, human ovarian OV2008 and its resistant pair of C13, and finally human lung carcinoma of HTB56 and its resistant pair of HTB56-CP were grown in the laboratory under the standard procedure. Saline was exposed to control cells, whereas 1, 5 and 10 µg/mL of cisplatin was exposed to experimental cells, for 1 h. Cells were then collected and lyophilized from which spectra were taken. According to our results, we could not trigger a well-recognized cells biomolecular band at 1015 cm(-1), being modified after exposure to cisplatin in all cell lines. On the other hand, there was a clear dose-dependent increase in protein β-sheet structure related peaks shift in resistant cell lines after exposure to cisplatin. This would probably indicate an easier protein interaction site for cisplatin in the resistant cell lines, which would probably inhibit cisplatin from binding to DNA, as the cytotoxic target. As a conclusion, FTIR biospectroscopy has proven its potency to identify the interactions, as well as the false engagement cellular sites for cisplatin in sensitive and resistant cell lines.

Novel mononuclear ruthenium(ii) complexes as potent and low-toxicity antitumour agents: synthesis, characterization, biological evaluation and mechanism of action

The ruthenium(ii) complex, [Ru(dmb)₂(salH)]PF₆(Ru-2), is considered a potential antitumour agent that could avoid the side-effects of platinum-based anti-cancer drugs, such as cisplatin, carboplatin or oxaliplatin.

Light-responsive AIE nanoparticles with cytosolic drug release to overcome drug resistance in cancer cells

A photo-active amphiphilic polymer containing a photosensitizer with aggregation-induced emission (AIE) characteristics was developed for light-responsive cytosolic drug release to overcome drug resistance.

Amphiphilic nanoparticles of resveratrol-norcantharidin to enhance the toxicity in zebrafish embryo

Direct coupling of a hydrophobic drug and a hydrophilic natural product via an ester bond produced an amphiphilic adduct that formed liposomes. Liposomes of resveratrol-norcantharidin adduct are capable of forming a tadpole-like nanoparticle and exhibited high toxicity in zebrafish embryos to give the better transportation and the effective concentration into cells. Using fluorescent chromophore showed the liposome in the stomach and intestinal villi rather than in the skin and muscle. This result may provide an insight into the mechanism of action of traditional Chinese medicines, which often contain a significant amount of flavonoids and polyphenol analogs.

Mesoporous Silica Nanoparticles Loaded with Cisplatin and Phthalocyanine for Combination Chemotherapy and Photodynamic Therapy in vitro

Mesoporous silica nanoparticles (MSNs) have been synthesized and loaded with both aluminum chloride phthalocyanine (AlClPc) and cisplatin as combinatorial therapeutics for treating cancer. The structural and photophysical properties of the MSN materials were characterized by different spectroscopic and microscopic techniques. Intracellular uptake and cytotoxicity were evaluated in human cervical cancer (HeLa) cells by confocal laser scanning microscopy (CLSM) and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assays, respectively. The CLSM experiments showed that the MSN materials can be readily internalized in HeLa cells. The cytotoxic experiments demonstrated that, after light exposure, the combination of both AlClPc and cisplatin compounds in the same MSN platform potentiate the toxic effect against HeLa cells in comparison to the control AlClPc-MSN and cisplatin-MSN materials. These results show the potential of using MSN platforms as nanocarriers for combination photodynamic and chemotherapies to treat cancer.

Self-assembled Multifunctional DNA Nanoflowers for the Circumvention of Multidrug Resistance in Targeted Anticancer Drug Delivery

Cancer chemotherapy has been impeded by side effects and multidrug resistance (MDR) partially caused by drug efflux from cancer cells, which call for targeted drug delivery systems additionally able to circumvent MDR. Here we report multifunctional DNA nanoflowers (NFs) for targeted drug delivery to both chemosensitive and MDR cancer cells and circumvent MDR in both leukemia and breast cancer cell models. NFs are self-assembled via liquid crystallization of DNA generated by Rolling Circle Replication, during which NFs are incorporated with aptamers for specific cancer cell recognition, fluorophores for bioimaging, and Doxorubicin (Dox)-binding DNA for drug delivery. NF sizes are tunable (down to ~200 nm in diameter), and the densely packed drug-binding motifs and porous intrastructures endow NFs with high drug loading capacity (71.4%, wt/wt). The Dox-loaded NFs (NF-Dox) are stable at physiological pH, yet drug release is facilitated in acidic or basic conditions. NFs deliver Dox into target chemosensitive and MDR cancer cells, preventing drug efflux and enhancing drug retention in MDR cells. Consequently, NF-Dox induces potent cytotoxicity in both target chemosensitive cells and MDR cells, but not nontarget cells, thus concurrently circumventing MDR and reducing side effects. Overall, these NFs are promising to circumvent MDR in targeted cancer therapy.

Multipronged Design of Light-Triggered Nanoparticles To Overcome Cisplatin Resistance for Efficient Ablation of Resistant Tumor

Chemotherapeutic drugs frequently encounter multiple drug resistance in the field of cancer therapy. The strategy has been explored with limited success for the ablation of drug-resistant tumor via intravenous administration. In this work, the rationally designed light-triggered nanoparticles with multipronged physicochemical and biological features are developed to overcome cisplatin resistance via the assembly of Pt(IV) prodrug and cyanine dye (Cypate) within the copolymer for efficient ablation of cisplatin-resistant tumor. The micelles exhibit good photostability, sustained release, preferable tumor accumulation, and enhanced cellular uptake with reduced efflux on both A549 cells and resistant A549R cells. Moreover, near-infrared light not only triggers the photothermal effect of the micelles for remarkable photothermal cytotoxicity, but also leads to the intracellular translocation of the micelles and reduction-activable Pt(IV) prodrug into cytoplasm through the lysosomal disruption, as well as the remarkable inhibition on the expression of a drug-efflux transporter, multidrug resistance-associated protein 1 (MRP1) for further reversal of drug resistance of A549R cells. Consequently, the multipronged effects of light-triggered micelles cause synergistic cytotoxicity against both A549 cells and A549R cells, and thus efficient ablation of cisplatin-resistant tumor without regrowth. The multipronged features of light-triggered micelles represent a versatile synergistic approach for the ablation of resistant tumor in the field of cancer therapy.

Functionalization of Platinum Complexes for Biomedical Applications

Platinum-based anticancer drugs are the mainstay of chemotherapy regimens in clinic. Nevertheless, the efficacy of platinum drugs is badly affected by serious systemic toxicities and drug resistance, and the pharmacokinetics of most platinum drugs is largely unknown. In recent years, a keen interest in functionalizing platinum complexes with bioactive molecules, targeting groups, photosensitizers, fluorophores, or nanomaterials has been sparked among chemical and biomedical researchers. The motivation for functionalization comes from some of the following demands: to improve the tumor selectivity or minimize the systemic toxicity of the drugs, to enhance the cellular accumulation of the drugs, to overcome the tumor resistance to the drugs, to visualize the drug molecules in vitro or in vivo, to achieve a synergistic anticancer effect between different therapeutic modalities, or to add extra functionality to the drugs. In this Account, we present different strategies being used for functionalizing platinum complexes, including conjugation with bisphosphonates, peptides, receptor-specific ligands, polymers, nanoparticles, magnetic resonance imaging contrast agents, metal chelators, or photosensitizers. Among them, bisphosphonates, peptides, and receptor-specific ligands are used for actively targeted drug delivery, polymers and nanoparticles are for passively targeted drug delivery, magnetic resonance imaging contrast agents are for theranostic purposes, metal chelators are for the treatment or prevention of Alzheimer's disease (AD), and photosensitizers are for photodynamic therapy of cancers. The rationales behind these designs are explained and justified at the molecular or cellular level, associating with the requirements for diagnosis, therapy, and visualization of biological processes. To illustrate the wide range of opportunities and challenges that are emerging in this realm, representative examples of targeted drug delivery systems, anticancer conjugates, anticancer theranostic agents, and anti-AD compounds relevant to functionalized platinum complexes are provided. All the examples exhibit new potential of platinum complexes for future applications in biomedical areas. The emphases of this Account are placed on the functionalization for targeted drug delivery and theranostic agents. In the end, a general assessment of various strategies has been made according to their major shortcomings and defects. The original information in this Account comes entirely from literature appearing since 2010.