Enhanced Cytotoxicity and Reactivity of a Novel Platinum(IV) Family with DNA-Targeting Naphthalimide Ligands

Advancements in platinum-based anticancer drug development: A comprehensive review of strategies, discoveries, and future perspectives

Platinum-based anticancer drugs have been at the forefront of cancer chemotherapy, with cisplatin emerging as a pioneer in the treatment of various malignancies. This review article provides a comprehensive overview of the evolution of platinum-based anticancer therapeutics, focusing on the development of cisplatin, platinum(IV) prodrugs, and the integration of photodynamic therapy (PDT) for enhanced cancer treatment results. The first section of the review delves into the historical context and molecular mechanisms underlying the success of cisplatin, highlighting its DNA binding properties and subsequent interference with cellular processes. Despite its clinical efficacy, the inherent limitations, including dose-dependent toxicities and acquired resistance, accelerated the exploration of novel platinum derivatives. This led to the emergence of platinum(IV) prodrugs, designed to overcome resistance mechanisms and enhance selectivity through targeted drug delivery. The subsequent section provides an in-depth analysis of the principles of design and structural modifications employed in the development of platinum(IV) prodrugs. The transitions to the incorporation of photodynamic therapy (PDT) stands out as a synergistic approach to platinum-based anticancer treatment. The photophysical properties of platinum complexes are discussed in the context of their potential application in PDT, emphasizing on combined cytotoxic effects of platinum-based drugs and light-induced reactive oxygen species generation. This dual-action approach holds great promise for overcoming the limitations of traditional chemotherapy as well as producing superior therapeutic outcomes. Overall, the present report explores the latest developments in the development and use of platinum complexes, highlighting novel strategies such combination treatments, targeted delivery methods, and the generation of multifunctional complexes. It also provides a comprehensive overview of the current landscape while proposing future directions for the development of next-generation platinum-based anticancer therapeutics.

Lysosome blockade induces divergent metabolic programs in macrophages and tumours for cancer immunotherapy

BACKGROUND

Platinum-drugs based chemotherapy in clinic increases the potency of tumor cells to produce M2 macrophages, thus leading to poor anti-metastatic activity and immunosuppression. Lysosome metabolism is critical for cancer cell migration and invasion, but how it promotes antitumor immunity in tumours and macrophages is poorly understood and the underlying mechanisms are elusive. The present study aimed to explore a synergistic strategy to dismantle the immunosuppressive microenvironment of tumours and metallodrugs discovery by using the herent metabolic plasticity.

METHODS

Naphplatin was prepared by coordinating an active alkaline moiety to cisplatin, which can regulate the lysosomal functions. Colorectal carcinoma cells were selected to perform the in vivo biological assays. Blood, tumour and spleen tissues were collected and analyzed by flow cytometry to further explore the relationship between anti-tumour activity and immune cells. Transformations of bone marrow derived macrophage (BMDM) and M2-BMDM to the M1 phenotype was confirmed after treatment with naphplatin. The key mechanisms of lysosome-mediated mucolipin-1(Mcoln1) and mitogen-activated protein kinase (MAPK) activation in M2 macrophage polarization have been unveiled. RNA sequencing (RNA-seq) was used to further explore the key mechanism underlying high-mobility group box 1(HMGB1)-mediated Cathepsin L(CTSL)-lysosome function blockade.

RESULTS

We demonstrated that naphplatin induces divergent lysosomal metabolic programs and reprograms macrophages in tumor cells to terminate the vicious tumour-associated macrophages (TAMs)-MDSCs-Treg triangle. Mechanistically, macrophages treated with naphplatin cause lysosome metabolic activation by triggering Ca2+ release via Mcoln1, which induces the activation of p38 and nuclear factor-κB (NF-κB) and finally results in polarizing M2 macrophages. In contrast, HMGB1-mediated lysosome metabolic blockade in cancer cells is strongly linked to antitumor effects by promoting cytoplasmic translocation of HMGB1.

CONCLUSIONS

This study reveals the crucial strategies of macrophage-based metallodrugs discovery that are able to treat both immunologically "hot" and "cold" cancers. Different from traditional platinum-based antitumour drugs by inhibition of DNAs, we also deliver a strong antitumour strategy by targeting lysosome to induce divergent metabolic programs in macrophages and tumours for cancer immunotherapy.

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.

Interacting mechanism of benzo(a)pyrene with free DNA in vitro

Polycyclic aromatic hydrocarbons are environmental pollutants with strong carcinogenicity, indirect teratogenicity, and mutagenicity. This study explored the interaction mechanism of benzo(a)pyrene with free DNA in vitro by using various analytical methods. UV-vis spectra showed that benzo(a)pyrene and DNA formed a new benzo(a)pyrene-DNA complex. The thermal melting temperature of DNA increased by 12.7 °C, showing that the intercalation of benzo(a)pyrene into DNA could promote the stability of the DNA double helix structure. The intercalation of benzo(a)pyrene with DNA in vitro was further confirmed by fluorescence microscopy with magnetic beads. Fluorescence spectra showed that the interaction between DNA and benzo(a)pyrene decreased the fluorescence intensity of benzo(a)pyrene, and the maximum quenching rate was 27.89%. The quenching mode of benzo(a)pyrene was static quenching. Thermodynamic data showed that the main driving forces were van der Waals forces and hydrogen bonds, and the reaction was spontaneous. The results of this study provided a novel insight for the establishment of polycyclic aromatic hydrocarbon capture and elimination through polycyclic aromatic hydrocarbon-DNA intercalation.

A trifunctional Pt(II) complex alleviates the NHEJ/HR-related DSBs repairs to evade cisplatin-resistance in NSCLC

Cisplatin, a representative of platinum-based drug, is clinically and widely used in the treatment of various types of malignant cancer. However, its non-selectivity to almost all the cell lines and resistance in long-term use severely limit its scope of use. As biotin-specific uptake systems are overexpressed in many types of tumors but rarely occur in normal tissues, making biotin a promising target for cancer treatment. In the study, we synthesized the Pt(II) complex C2 and determined its biological activities. The existence of biotin enhanced the ability of the complex to target tumors, while the introduction of a naphthalimide compound makes it possible to diagnose tumors and monitor their progress. We have also introduced a known Pt(II) complex DN604, which not only retains the excellent cytotoxicity of platinum drugs, but also inhibits the expression of DNA double-strand breaks (DSBs) repair-related NHEJ protein Ku70 and HR protein Rad51. In summary, we report a novel trifunctional Pt(II) complex that could target tumor cells, monitor tumor progression, and reverse DSBs repair-induced cisplatin-resistance.

A Pt(IV)-based mononitro-naphthalimide conjugate with minimized side-effects targeting DNA damage response via a dual-DNA-damage approach to overcome cisplatin resistance

Platinum(Pt)(II) drugs and new Pt(IV) agents behave the dysregulation of apoptosis as the result of DNA damage repair and thus, are less effective in the treatment of resistant tumors. Herein, mononitro-naphthalimide Pt(IV) complex 10b with minimized side-effects was reported targeting DNA damage response via a dual-DNA-damage approach to overcome cisplatin resistance. 10b displayed remarkably evaluated antitumor (70.10%) activities in vivo compared to that of cisplatin (52.88%). The highest fold increase (FI) (5.08) for A549cisR cells and the lowest (0.72) for A549 indicated 10b preferentially accumulated in resistant cell lines. The possible molecular mechanism indicates that 10b targets resistant cells in a totally different way from the existing Pt drugs. The cell accumulation and the Pt levels in genomic DNA from 10b is almost 5 folds higher than that of cisplatin and oxaliplatin, indicating the naphthalimide moiety in 10b exhibits preferentially DNA damage. Using 5'-dGMP as a DNA model, the DNA-binding properties of 10b (1 mM) with 5'-dGMP (3 mM) in the presence of ascorbic acid (5 mM) deduced that 10b was generated by the combination of cisplatin with 5'-dGMP after reduction by ascorbic acid. Moreover, 10b promoted the expression of p53 gene and protein more effectively than cisplatin, leading to the increased anticancer activity. The up-regulated γH2A.X and down-regulated RAD51 indicates that 10b not only induced severe DNA damage but also inhibited the DNA damage repair, thus resulting in its higher cytotoxicity in comparison to that of cisplatin. Their preferential accumulation in cancer cells (SMMC-7721) compared to the matched normal cells (HL-7702 cells) demonstrated that they were potentially safe for clinical therapeutic use. In addition, the higher therapeutic indices of 10b for 4T1 cells in vivo indicated that naphthalimide-Pt(IV) conjugates behaved a vital function in the treatment of breast cancer. For the first time, our study implies a significant strategy for Pt drugs to treat resistance cancer targeting DNA damage repair via dual DNA damage mechanism in a totally new field.

Targeting drug delivery system for platinum(Ⅳ)-Based antitumor complexes

Classical platinum(II) anticancer agents are widely-used chemotherapeutic drugs in the clinic against a range of cancers. However, severe systemic toxicity and drug resistance have become the main obstacles which limit their application and effectiveness. Because divalent cisplatin analogues are easily destroyed in vivo, their bioavailability is low and no selective to tumor tissues. The platinum(IV) prodrugs are attractive compounds for cancer treatment because they have great advantages, e.g., higher stability in biological media, aqueous solubility and no cross-resistance with cisplatin, which may become the next generation of platinum anticancer drugs. In addition, platinum(IV) drugs could be taken orally, which could be more acceptable to cancer patients, breaking the current situation that platinum(II) drugs can only be given by injection. The coupling of platinum(IV) complexes with tumor targeting groups avoids the disadvantages such as instability in blood, irreversible binding to plasma proteins, rapid renal clearance, and non-specific distribution in normal tissues. Because of the above advantages, the combination of platinum complexes and tumor targeting groups has become the hottest field in the research and development of new platinum drugs. These approaches can be roughly categorized into two groups: active and passive targeted strategies. This review concentrates on various targeting and delivery strategies for platinum(IV) complexes to improve the efficacy and reduce the side effects of platinum-based anticancer drugs. We have made a summary of the related articles on platinum(IV) targeted delivery in recent years. We believe the results of the studies described in this review will provide new ideas and strategies for the development of platinum drugs.

Enhancing Cytotoxicity of a Monofunctional Platinum Complex via a Dual-DNA-Damage Approach

Mitochondrial DNA (mtDNA) is an attractive cellular target for anticancer agents in addition to nuclear DNA (nDNA). The cationic platinum(II) complex cis-[Pt(NP)(NH₃)₂Cl]NO₃ (PtNP, NP = N-(2-ethylpyridine)-1,8-naphthalimide) bearing the DNA-intercalating moiety NP was designed. The structure of PtNP was fully characterized by single-crystal X-ray crystallography, NMR, and HRMS. PtNP is superior to cisplatin in both in vitro and in vivo anticancer activities with low systemic toxicity. The interaction of PtNP with CT-DNA demonstrated that PtNP could effectively bind to DNA through both covalent and noncovalent double binding modes. In addition to causing significant damage to nDNA and remarkable inhibition to DNA damage repair, PtNP also distributed in mitochondria, inducing mtDNA damage and affecting the downstream transcriptional level of mitochondrion-encoded genes. In addition, PtNP disturbed the physiological processes of mitochondria by reducing the mitochondrial membrane potential and promoting the generation of reactive oxygen species. Mechanistic studies demonstrate that PtNP induced apoptosis via mitochondrial pathways by upregulating Bax and Puma and downregulating Bcl-2 proteins, leading to the release of cytochrome c and activation of caspase-3 and caspase-9. As a dual-DNA-damage agent, PtNP is able to improve the anticancer activity by damaging both nuclear and mitochondrial DNA, thus providing a new anticancer mechanism of action for the naphthalimide monofunctional platinum(II) complexes.

A Subset of New Platinum Antitumor Agents Kills Cells by a Multimodal Mechanism of Action Also Involving Changes in the Organization of the Microtubule Cytoskeleton

The substitution inert platinum agent [Pt(1 S,2 S-diaminocyclohexane)(5,6-dimethyl-1,10-phenanthroline)]²⁺ (56MeSS, 5) is a potent cytotoxic metallodrug. In contrast to conventional cisplatin or oxaliplatin, the mechanism of action (MoA) of 5 is fundamentally different. However, details of the mechanism by which the 5,6-dimethyl-1,10-phenanthroline ligand contributes to the cytotoxicity of 5 and its derivatives have not been sufficiently clarified so far. Here, we show that 5 and its Pt(IV) derivatives exhibit an intriguing potency in the triple-negative breast cancer cells MDA-MB-231. Moreover, we show that the Pt(IV) derivatives of 5 act by multimodal MoA resulting in the global biological effects, that is, they damage nuclear DNA, reduce the mitochondrial membrane potential, induce the epigenetic processes, and last but not least, the data provide evidence that changes in the organization of cytoskeleton networks are functionally important for 5 and its derivatives, in contrast to clinically used platinum cytostatics, to kill cancer cells.

A conveniently synthesized Pt (IV) conjugated alginate nanoparticle with ligand self-shielded property for targeting treatment of hepatic carcinoma

The clinical translation remains a major challenge for platinum drug loaded nanoparticle due to the complexity of composition and preparation. Here we employed only three ingredients to prepare Pt (IV) prodrug-loaded ligand-induced self-assembled nanoparticles (GA-ALG@Pt NPs) via facile one-pot route for liver tumor treatment. GA-ALG@Pt NPs were found equipped with intelligently ligand self-shielded property in which the internal GA could be induced to expose by initial cellular recognition, resulting in strengthened cellular uptake (20%-30%) and prolonged blood circulation time (3.43 times). Appreciable tumor targeting ability (2 times) and especially tumor selectivity (2.5 times) were obtained. Glutathione-triggered release of therapeutic agent generated satisfactory antitumor effect. Bio-safety is also a distinguishing feature of GA-ALG@Pt NPs that greatly relief the nephrotoxicity and systematic toxicity of cisplatin. This conveniently synthesized nanoparticle processes superior targeting capacity and biosecurity, supplying an effective approach to translational cancer therapy in the future.

l,8-Naphthalimide based DNA intercalators and anticancer agents. A systematic review from 2007 to 2017

In this review, we describe a detailed investigation about the structural variations and relative activity of 1,8-naphthalimide based intercalators and anticancer agents. The 1,8-naphthalimides binds to the DNA via intercalation, and exert their antitumor activities through Topoisomerase I/II inhibition, photoinduced DNA damage or related mechanism. Here, our discussion focused on works published over the last ten years (2007-2017) related to therapeutic applications, in the order of cancer treatment followed by other properties of 1,8-naphthalimides. In preparing for this review, we considered that several seminal reviews have appeared over the last fifteen years and focused on closely related subjects, however, none of them is exhaustive.

Design and synthesis of a new series of low toxic naphthalimide platinum(IV) antitumor complexes with dual DNA damage mechanism

Naphthalimide platinum(IV) antitumor complexes with potential dual DNA damage mechanism were designed, synthesized and evaluated for antitumor activities. The incorporation of DNA targeted naphthalimide group to the platinum(IV) system exerts much positive impacts on their antitumor efficacy. The mechanism research reveals that the title compounds could interact with dsDNA in platinum(IV) form via the naphthalimide group and cause DNA lesion. The further reduction would release platinum(II) complexes and naphthalimide acids which would induce remarkable secondary damage to DNA. Furthermore, the naphthalimide platinum(IV) compounds could combine with human serum albumin via electrostatic force, which are favourable for their storage and transport in blood. Moreover, the title compounds exhibit higher accumulation in tumor cells, and exert lower toxic and higher safe properties than oxaliplatin in vivo.