Effective platinum(IV) prodrugs conjugated with lonidamine as a functional group working on the mitochondria

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.

Mitochondria-Targeted Multifunctional Nanoprodrugs by Inhibiting Metabolic Reprogramming for Combating Cisplatin-Resistant Lung Cancer

How to address the resistance of cisplatin (CDDP) has always been a clinical challenge. The resistance mechanism of platinum-based drugs is very complex, including nuclear DNA damage repair, apoptosis escape, and tumor metabolism reprogramming. Tumor cells can switch between mitochondrial oxidative phosphorylation (OXPHOS) and glycolysis and develop resistance to chemotherapy drugs through metabolic variability. In addition, due to the lack of histone protection and a relatively weak damage repair ability, mitochondrial DNA (mtDNA) is more susceptible to damage, which in turn affects mitochondrial OXPHOS and can become a potential target for platinum-based drugs. Therefore, mitochondria, as targets of anticancer drugs, have become a hot topic in tumor resistance research. This study constructed a self-assembled nanotargeted drug delivery system LND-SS-Pt-TPP/HA-CD. β-Cyclodextrin-grafted hydronic acid (HA-CD)-encapsulated prodrug nanoparticles can target CD44 on the tumor surface and further deliver the prodrug to intracellular mitochondria through a triphenylphosphine group (TPP+). Disulfide bonds can be selectively degraded by glutathione (GSH) in mitochondria, releasing lonidamine (LND) and the cisplatin prodrug (Pt(IV)). Under the action of GSH and ascorbic acid, Pt(IV) is further reduced to cisplatin (Pt(II)). Cisplatin can cause mtDNA damage, induce mitochondrial dysfunction and mitophagy, and then affect mitochondrial OXPHOS. Meanwhile, LND can reduce the hexokinase II (HK II) level, induce destruction of mitochondria, and block energy supply by glycolysis inhibition. Ultimately, this self-assembled nano targeted delivery system can synergistically kill cisplatin-resistant lung cancer cells, which supplies an overcome cisplatin resistance choice via the disrupt mitochondria therapy.

Pt(IV) Complexes in the Search for Novel Platinum Prodrugs with Promising Activity

The kinetically inert, six coordinated, octahedral Pt(IV) complexes are termed dual-, triple-, or multi-action prodrugs based on the nature of the axially substituted ligands. These ligands are either inert or biologically active, where the nature of these axial ligands provides additional stability, synergistic biological activity or cell-targeting ability. There are many literature reports from each of these classes, mentioning the varied nature of these axial ligands. The ligands comprise drug molecules such as chlorambucil, doxorubicin, valproic acid, ethacrynic acid, biologically active chalcone, coumarin, combretastatin, non-steroidal anti-inflammatory drugs (NSAIDs) and many more, potentiating the anti-proliferative profile or reducing the side effects associated with cisplatin therapy. The targeting and non-targeting nature of these moieties exert additive or synergistic effects on the anti-cancer activity of Pt(II) moieties. Herein, we discuss the effects of these axially oriented ligands and the changes in the non-leaving am(m)ine groups and in the leaving groups on the biological activity. In this review, we have presented the latest developments in the field of Pt(IV) complexes that display promising activity with a reduced resistance profile. We have discussed the structure activity relationship (SAR) and the effects of the ligands on the biological activity of Pt(IV) complexes with cisplatin, oxaliplatin, carboplatin and the Pt core other than approved drugs. This literature work will help researchers to get an idea about Pt(IV) complexes that have been classified based on the aspects of their biological activity.

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.

Is antitumor Pt(IV) complex containing two axial lonidamine ligands a true dual- or multi-action prodrug?

This work studied the mechanism of action of a Pt(IV) complex 2 bearing two axial lonidamine ligands, which are selective inhibitors of aerobic glycolysis. The presence of two lonidamine ligands in 2 compared to the parent Pt(II) complex increased its antiproliferative activity, cellular accumulation, and changed its cell cycle profile and mechanism of cell death. In 3D cell culture, 2 showed exceptional antiproliferative activity with IC50 values as low as 1.6 μM in MCF7 cells. The study on the influence of the lonidamine ligands in the Pt complex on glycolysis showed only low potency of ligands to affect metabolic processes in cancer cells, making the investigated complex, not a dual- or multi-action prodrug. However, the Pt(IV) prodrug effectively delivers the cytotoxic Pt(II) complex into cancer cells.

Carrier-free prodrug nanoparticles based on lonidamine and cisplatin for synergistic treatment of breast cancer

Herein, we combined a derivative of cisplatin (CP) and the chemosensitizer lonidamine (LND) to design an amphiphilic prodrug, in which the ratio of LND to cisplatin was fixed at 2:1. Diaminedichlorodihydroxyplatinum (DH-CP) is a hydrophilic cisplatin derivative. Due to its appropriate amphiphilicity, this prodrug could self-assemble into stable nanoparticles (denoted as LNP-NPs). Under the action of excessive glutathione (GSH) in tumor cells, DH-CP could be reduced to cytotoxic cisplatin. In addition, the released LND could inhibit the metabolic process of tumor cells, and improving the sensitivity of tumor cells to cisplatin. In vitro studies demonstrated that LNP-NPs displayed significantly cytotoxicity on breast cancer cells, and the cell viability after co-incubation for 48 h (CP 16 μg/mL) were 18.77% (MCF-7) and 20.01% (EMT6), respectively. LNP-NPs could also significantly inhibit the growth of MCF-7 tumor-like spheroids, which were realized through the high coordination and cooperation between CP and LND. Therefore, the carrier-free drug delivery system based on LND and DH-CP is expected to achieve a good synergistic anti-tumor effect.

Cu(I) and Cu(II) Complexes Based on Lonidamine-Conjugated Ligands Designed to Promote Synergistic Antitumor Effects

Bis(pyrazol-1-yl)- and bis(3,5-dimethylpyrazol-1-yl)-acetates were conjugated with the 2-hydroxyethylester and 2-aminoethylamide derivatives of the antineoplastic drug lonidamine to prepare Cu(I) and Cu(II) complexes that might act through synergistic mechanisms of action due to the presence of lonidamine and copper in the same chemical entity. Synchrotron radiation-based complementary techniques [X-ray photorlectron spectroscopy and near-edge X-ray absorption fine structure (NEXAFS)] were used to characterize the electronic and molecular structures of the complexes and the local structure around the copper ion (XAFS) in selected complexes. All complexes showed significant antitumor activity, proving to be more effective than the reference drug cisplatin in a panel of human tumor cell lines, and were able to overcome oxaliplatin and multidrug resistance. Noticeably, these Cu complexes appeared much more effective than cisplatin against 3D spheroids of pancreatic PSN-1 cancer cells; among these, PPh₃-containing Cu(I) complex 15 appeared to be the most promising derivative. Mechanistic studies revealed that 15 induced cancer cell death by means of an apoptosis-alternative cell death.

Investigation on Optical and Biological Properties of 2-(4-Dimethylaminophenyl)benzothiazole Based Cycloplatinated Complexes

The optical and biological properties of 2-(4-dimethylaminophenyl)benzothiazole cycloplatinated complexes featuring bioactive ligands ([{Pt(Me2 N-pbt)(C6 F5 )}L] [L=Me2 N-pbtH 1, p-dpbH (4-(diphenylphosphino)benzoic acid) 2, o-dpbH (2-(diphenylphosphino)benzoic acid) 3), [Pt(Me2 N-pbt)(o-dpb)] 4, [{Pt(Me2 N-pbt)(C6 F5 )}2 (μ-PRn P)] [PR4 P=O(CH2 CH2 OC(O)C6 H4 PPh2 )2 5, PR12 P=O{(CH2 CH2 O)3 C(O)C6 H4 PPh2 }2 6] are presented. Complexes 1-6 display 1 ILCT and metal-perturbed 3 ILCT dual emissions. The ratio between both bands is excitation dependent, accomplishing warm-white emissions for 2, 5 and 6. The phosphorescent emission is lost in aerated solutions owing to photoinduced electron transfer to 3 O2 and the formation of 1 O2 , as confirmed in complexes 2 and 4. They also exhibit photoinduced phosphorescence enhancement in non-degassed DMSO due to local oxidation of DMSO by sensitized 1 O2 , which causes a local degassing. Me2 N-pbtH and the complexes specifically accumulate in the Golgi apparatus, although only 2, 3 and 6 were active against A549 and HeLa cancer cell lines, 6 being highly selective in respect to nontumoral cells. The potential photodynamic property of these complexes was demonstrated with complex 4.

Recent Progresses in Conjugation with Bioactive Ligands to Improve the Anticancer Activity of Platinum Compounds

Platinum (Pt) drugs, including cisplatin, are widely used for the treatment of solid tumors. Despite the clinical success, side effects and occurrence of resistance represent major limitations to the use of clinically available Pt drugs. To overcome these problems, a variety of derivatives have been designed and synthetized. Here, we summarize the recent progress in the development of Pt(II) and Pt(IV) complexes with bioactive ligands. The development of Pt(II) and Pt(IV) complexes with targeting molecules, clinically available agents, and other bioactive molecules is an active field of research. Even if none of the reported Pt derivatives has been yet approved for clinical use, many of these compounds exhibit promising anticancer activities with an improved pharmacological profile. Thus, planning hybrid compounds can be considered as a promising approach to improve the available Pt-based anticancer agents and to obtain new molecular tools to deepen the knowledge of cancer progression and drug resistance mechanisms.

Mitochondria and Endoplastic Reticulum Targeting Strategy for Enhanced Phototherapy

To ensure improved efficacy and minimized toxicity of therapeutic molecules, it is generally accepted that specifically delivering them to the subcellular site of their action will be attractive. Phototherapy has received considerable attention because of its noninvasiveness, high temporal-spatial resolution, and minimal drug resistance. As important functional organelles in cells, mitochondria and endoplasmic reticulum (ER) participate in fundamental cellular processes, which make them much more sensitive to reactive oxygen species (ROS) and hyperthermia. Thus, mitochondria- or ER-targeted phototherapy will be rational strategies for synergetic cancer therapy. In this review, we focus on the latest advances in molecules and nanomaterials currently used for mitochondria- and ER-targeted phototherapy.

Design, synthesis and biological evaluation of dihydro-2-quinolone platinum(iv) hybrids as antitumor agents displaying mitochondria injury and DNA damage mechanism

The design of novel platinum(iv) complexes with mitochondria injury competence, besides the DNA damage mechanism, is a promising way to develop new platinum drugs. Herein, dihydro-2-quinolone (DHQLO) as a mitocan was incorporated into the platinum(iv) system for the first time to prepare a new series of DHQLO platinum(iv) compounds. Complex 1b could effectively inhibit the proliferation of tumor cells in vitro and in vivo. It accumulated at higher levels in both whole cells and DNA, and easily underwent intercellular reduction to release platinum(ii) and DHQLO moieties. The released platinum(ii) complex caused serious DNA damage by covalent conjunction with the DNA duplex, and remarkably increased the expression of the γ-H2AX protein. Moreover, 1b also caused serious mitochondria injury to induce mitochondrial membrane depolarization and increase ROS generation. Such actions upon DNA and mitochondria activate the p53 apoptotic pathway synergetically in tumor cells by upregulating the protein p53 and apoptotic proteins caspase9 and caspase3, which efficiently promoted the apoptotic death of tumor cells. Compound 1b with such synergic mechanism exhibited great potential in reversing cisplatin resistance and improving antitumor efficacies.

ANTs and cancer: Emerging pathogenesis, mechanisms, and perspectives

Adenine nucleotide translocases (ANTs) are a class of transporters located in the inner mitochondrial membrane that not only couple processes of cellular productivity and energy expenditure, but are also involved in the composition of the mitochondrial membrane permeability transition pore (mPTP). The function of ANTs has been found to be most closely related to their own conformational changes. Notably, as multifunctional proteins, ANTs play a key role in oncogenesis, which provides building blocks for tumor anabolism, control oxidative phosphorylation and glycolysis homeostasis, and govern cell death. Thus, ANTs constitute promising targets for the development of novel anticancer agents. Here, we review the recent findings regarding ANTs and their important mechanisms in cancer, with a focus on the therapeutic potential of targeting ANTs for cancer therapy.

The Potential of Lonidamine in Combination with Chemotherapy and Physical Therapy in Cancer Treatment

Simple Summary

The unique characteristics of tumor energy metabolism (highly dependent on aerobic glycolysis, namely, the Warburg effect) make it an interesting and attractive target for drug discovery. Radio- and chemoresistance are closely associated with the Warburg effect. Lonidamine (LND), as a glycolytic inhibitor, although having low anticancer activity when used alone, exhibits selectivity to various tumors, and its adverse effects do not overlap when combined with other chemotherapeutic drugs. Therefore, LND may be very promising as a sensitizer of tumors to chemotherapeutic agents and physical therapies. This review summarizes the advance of LND in combination with chemotherapy and physical therapy over the past several decades, as well as the promising LND derivative adjudin (ADD). The underlying sensitizing mechanisms were also analyzed and discussed, which may contribute to an improved therapeutic effect in future clinical cancer treatment.

Abstract

Lonidamine (LND) has the ability to resist spermatogenesis and was first used as an anti-spermatogenic agent. Later, it was found that LND has a degree of anticancer activity. Currently, LND is known to target energy metabolism, mainly involving the inhibition of monocarboxylate transporter (MCT), mitochondrial pyruvate carrier (MPC), respiratory chain complex I/II, mitochondrial permeability transition (PT) pore, and hexokinase II (HK-II). However, phase II clinical studies showed that LND alone had a weak therapeutic effect, and the effect was short and reversible. Interestingly, LND does not have the common side effects of traditional chemotherapeutic drugs, such as alopecia and myelosuppression. In addition, LND has selective activity toward various tumors, and its toxic and side effects do not overlap when combined with other chemotherapeutic drugs. Therefore, LND is commonly used as a chemosensitizer to enhance the antitumor effects of chemotherapeutic drugs based on its disruption of energy metabolism relating to chemo- or radioresistance. In this review, we summarized the combination treatments of LND with several typical chemotherapeutic drugs and several common physical therapies, such as radiotherapy (RT), hyperthermia (HT), and photodynamic therapy (PDT), and discussed the underlying mechanisms of action. Meanwhile, the development of novel formulations of LND in recent years and the research progress of LND derivative adjudin (ADD) as an anticancer drug were also discussed.

Multifunctional Pt(iv) complexes containing a glutathione S-transferase inhibitor lead to enhancing anticancer activity and preventing metastasis of osteosarcoma cells

Cisplatin has been clinically applied in the treatment of osteosarcoma (OS), but its efficacy is severely limited due to drug resistance and metastasis. One of the chief culprits is the overexpression of glutathione S-transferases (GSTs) in cancer cells, which can accelerate the interaction of glutathione (GSH) with cisplatin, reducing its biological effects. In this study, three Pt(iv) complexes derived from cisplatin conjugated with a GST inhibitor (NBDHEX) were designed and synthesized. The stabilities and releasing capabilities of these complexes, as well as their abilities to inhibit GSTs, were investigated together with their in vitro anticancer activities toward osteosarcoma cells. Among them, complex 2, bearing one NBDHEX derivative and a hydroxyl group at the axial positions, could markedly kill human OS cells due to its suitable stability and prominent ability to inhibit GSTs. Meanwhile, it can prevent the metastasis of OS via down-regulating Akt. Thus, complex 2 has the potential for further research for the treatment of OS.

Recent advances in platinum-based chemotherapeutics that exhibit inhibitory and targeted mechanisms of action

Current platinum-based drugs used in chemotherapy, like cisplatin and its derivatives, are greatly limited due to side-effects and drug resistance. This has inspired the search for novel platinum-based drugs that deviate from the conventional mechanism of action seen with current chemotherapeutics. This review highlights recent advances in platinum(II) and platinum(IV)-based complexes that have been developed within the past six years. The platinum compounds explored within this review are those that display a more targeted approach by incorporating ligands that act on selected cellular targets within cancer cells. This includes mitochondria, overexpressed receptors or proteins and enzymes that contribute to cancer cell proliferation. These types of platinum compounds have shown significant improvements in anticancer activity and as such, this review highlights the importance of pursuing these new designed platinum drugs for cancer therapy, with the potential of undergoing clinical trials.

Investigations of the Kinetics and Mechanism of Reduction of a Carboplatin Pt(IV) Prodrug by the Major Small-Molecule Reductants in Human Plasma

The development of Pt(IV) anticancer prodrugs to overcome the detrimental side effects of Pt(II)-based anticancer drugs is of current interest. The kinetics and reaction mechanisms of the reductive activation of the carboplatin Pt(IV) prodrug cis,trans-[Pt(cbdca)(NH₃)₂Cl₂] (cbdca = cyclobutane-1,1-dicarboxylate) by the major small-molecule reductants in human plasma were analyzed in this work. The reductants included ascorbate (Asc), the thiol-containing molecules L-cysteine (Cys), DL-homocysteine (Hcy), and glutathione (GSH), and the dipeptide Cys–Gly. Overall second-order kinetics were established in all cases. At the physiological pH of 7.4, the observed second-order rate constants k′ followed the order Asc << Cys–Gly ~ Hcy < GSH < Cys. This reactivity order together with the abundances of the reductants in human plasma indicated Cys as the major small-molecule reductant in vivo, followed by GSH and ascorbate, whereas Hcy is much less important. In the cases of Cys and GSH, detailed reaction mechanisms and the reactivity of the various protolytic species at physiological pH were derived. The rate constants of the rate-determining steps were evaluated, allowing the construction of reactivity-versus-pH distribution diagrams for Cys and GSH. The diagrams unraveled that species III of Cys (⁻SCH₂CH(NH₃⁺)COO⁻) and species IV of GSH (⁻OOCCH(NH₃⁺)CH₂CH₂CONHCH(CH₂S⁻)- CONHCH₂COO⁻) were exclusively dominant in the reduction process. These two species are anticipated to be of pivotal importance in the reduction of other types of Pt(IV) prodrugs as well.

A cisplatin-based platinum(IV) prodrug containing a glutathione s-transferase inhibitor to reverse cisplatin-resistance in non-small cell lung cancer

A Pt(IV) prodrug of cisplatin containing a glutathione s-transferase (GSTs) inhibitor 6-(7-nitro-2,1,3-benzoxadiazol-4-ylthio)hexanol (NBDHEX), complex 1, was designed and studied aiming to overcome cisplatin-resistance and reduce its toxicity by inhibiting GSTs overexpressed in cancer cells. The complex could be reduced to release its active Pt(II) species and axial ligand in the presence of ascorbic acid. In cytotoxicity study, complex 1 showed more potent anticancer activity than cisplatin and NBDHEX against all the tested cancer cells, especially toward cisplatin resistant A549/DDP cells with a resistance factor value of 0.37. By effectively inhibiting GSTs, complex 1 was found to be able to promote higher platinum uptake and cause more severe DNA damage in both A549 cells and A549/DDP cells as compared with cisplatin. Further mechanism study indicated that it could trigger cell death via an apoptotic pathway. In vivo tests on A549 xenograft tumor mice model showed that complex 1 presented higher tumor inhibiting rate and lower toxicity than cisplatin as well. In all, the Pt(IV) prodrug has potential to be developed as an anticancer agent.

Toward Multi-Targeted Platinum and Ruthenium Drugs-A New Paradigm in Cancer Drug Treatment Regimens?

While medicinal inorganic chemistry has been practised for over 5000 years, it was not until the late 1800s when Alfred Werner published his ground-breaking research on coordination chemistry that we began to truly understand the nature of the coordination bond and the structures and stereochemistries of metal complexes. We can now readily manipulate and fine-tune their properties. This had led to a multitude of complexes with wide-ranging biomedical applications. This review will focus on the use and potential of metal complexes as important therapeutic agents for the treatment of cancer. With major advances in technologies and a deeper understanding of the human genome, we are now in a strong position to more fully understand carcinogenesis at a molecular level. We can now also rationally design and develop drug molecules that can either selectively enhance or disrupt key biological processes and, in doing so, optimize their therapeutic potential. This has heralded a new era in drug design in which we are moving from a single- toward a multitargeted approach. This approach lies at the very heart of medicinal inorganic chemistry. In this review, we have endeavored to showcase how a "multitargeted" approach to drug design has led to new families of metallodrugs which may not only reduce systemic toxicities associated with modern day chemotherapeutics but also address resistance issues that are plaguing many chemotherapeutic regimens. We have focused our attention on metallodrugs incorporating platinum and ruthenium ions given that complexes containing these metal ions are already in clinical use or have advanced to clinical trials as anticancer agents. The "multitargeted" complexes described herein not only target DNA but also contain either vectors to enable them to target cancer cells selectively and/or moieties that target enzymes, peptides, and intracellular proteins. Multitargeted complexes which have been designed to target the mitochondria or complexes inspired by natural product activity are also described. A summary of advances in this field over the past decade or so will be provided.

Current Developments in Pt(IV) Prodrugs Conjugated with Bioactive Ligands

To overcome the side effects of and resistance to cisplatin, a variety of Pt(IV) prodrugs were designed and synthesized via different modifications including combination with lipid chains to increase hydrophobicity, conjugation with short peptide chains or nanoparticles to improve drug delivery, or addition of bioactive ligands to the axial positions of Pt(IV) complexes to exert dual-function effects. This review summarizes the recent progress in the development of Pt(IV) prodrugs conjugated with bioactive-targeting ligands, including histone deacetylase inhibitors, p53 agonists, alkylating agents, and nonsteroidal anti-inflammatory agents. Although Pt(IV) complexes that conjugated with bioactive ligands show satisfactory anticancer effects, none has been approved for clinical use. Therefore, we hope that this review will contribute to further study and development of Pt(IV) complexes conjugated with bioactive and other ligands.

Chlorambucil-conjugated platinum(IV) prodrugs to treat triple-negative breast cancer in vitro and in vivo

Modification of platinum (II) into lipophilic platinum (IV) compounds by introducing biologically active molecules were widely employed to develop new platinum-based prodrugs in the past decade. In this paper, two chlorambucil platinum (IV) complexes, CLB-Pt and CLB-Pt-CLB, were synthesized and displayed very potent antiproliferative activity against all the tested cancer cell lines, such as A549, HeLa and MCF-7, especially to treat the well-known refractory triple-negative breast cancer. CLB-Pt-CLB significantly improved cell-killing effect in triple-negative subtype MDA-MB-231 cells, and showed much stronger cytotoxicity than either monotherapy or combination of cisplatin and chlorambucil. CLB-Pt-CLB prodrug entered cells in dramatically increased amount compared with cisplatin and enhanced DNA damage, inducing cancer cell apoptosis. It exhibited high anticancer activity and no observable toxicity in BALB/c nude mice bearing MDA-MB-231 tumors. The chlorambucil moiety not only greatly assisted the passive diffusion of CLB-Pt-CLB into cells, but also produced the synergism with cisplatin in targeting DNA.

α-Diimine homologues of cisplatin: synthesis, speciation in DMSO/water and cytotoxicity

α-Diimine Pt(ii) complexes display variable stability in DMSO and DMSO/water mixtures, depending on the nature of the N-substituents. The most stable compounds are moderately cytotoxic, or are essentially inactive, against A2780 and A2780cisR cancer cell lines.