Anticancer Melatplatin Prodrugs: High Effect and Low Toxicity, MT1-ER-Target and Immune Response In Vivo

Discovery of Novel p53-MDM2 Inhibitor (RG7388)-Conjugated PlatinumIV Complexes as Potent Antitumor Agents

While a number of p53-MDM2 inhibitors have progressed into clinical trials for the treatment of cancer, their progression has been hampered by a variety of problems, including acquired drug resistance, dose-dependent toxicity, and limited clinical efficiency. To make more progress, we integrated the advantages of MDM2 inhibitors and platinum drugs to construct novel PtIV-RG7388 (a selective MDM2 inhibitor) complexes. Most complexes, especially 5a and 5b, displayed greatly improved antiproliferative activity against both wild-type and mutated p53 cancer cells. Remarkably, 5a exhibited potent in vivo tumor growth inhibition in the A549 xenograft model (66.5%) without apparent toxicity. It arrested the cell cycle at both the S phase and the G2/M phase and efficiently induced apoptosis via the synergistic effects of RG7388 and cisplatin. Altogether, PtIV-RG7388 complex 5a exhibited excellent in vitro and in vivo antitumor activities, highlighting the therapeutic potential of PtIV-RG7388 complexes as antitumor agents.

Exploring cyclopropylamine containing cyanopyrimidines as LSD1 inhibitors: Design, synthesis, ADMET, MD analysis and anticancer activity profiling

In this series we report the structure-based design, synthesis and anticancer activity evaluation of a series of eighteen cyclopropylamine containing cyanopyrimidine derivatives. The computational predictions of ADMET properties revealed appropriate aqueous solubility, high GI absorption, no BBB permeability, no Lipinski rule violations, medium total clearance and no mutagenic, tumorigenic, irritant and reproductive toxic risks for most of the compounds. Compounds VIIb, VIIi and VIIm emerged as the most potent anticancer agents among all compounds evaluated against 60 cancer cell lines through the one-dose (10 µM) sulforhodamine B assay. Further, the multiple dose cell viability studies against cancer cell lines MOLT-4, A549 and HCT-116 revealed results consistent with the one-dose assay, besides sparing normal cell line HEK-293. The three potent compounds also displayed potent LSD1 inhibitory activity with IC50 values of 2.25, 1.80 and 6.08 µM. The n-propyl-thio/isopropyl-thio group bonded to the pyrimidine ring and unsubstituted/ electron donating group (at the para- position) attached to the phenyl ring resulted in enhanced anticancer activity. However, against leukemia cancer, the electron donating isopropyl group remarkably enhanced anti-cancer activity. Our findings provide important leads, which merit further optimization to result in better cancer therapeutics.

Inhibition of NF-κB-Mediated Proinflammatory Transcription by Ru(II) Complexes of Anti-Angiogenic Ligands in Triple-Negative Breast Cancer

Nuclear factor kappa beta (NF-κB) plays a pivotal role in breast cancer, particularly triple-negative breast cancer, by promoting inflammation, proliferation, epithelial-mesenchymal transition, metastasis, and drug resistance. Upregulation of NF-κB boosts vascular endothelial growth factor (VEGF) expression, assisting angiogenesis. The Ru(II) complexes of methyl- and dimethylpyrazolyl-benzimidazole N,N donors inhibit phosphorylation of ser536 in p65 and translocation of the NF-κB heterodimer (p50/p65) to the nucleus, disabling transcription to upregulate inflammatory signaling. The methyl- and dimethylpyrazolyl-benzimidazole inhibit VEGFR2 phosphorylation at Y1175, disrupting downstream signaling through PLC-γ and ERK1/2, ultimately suppressing Ca(II)-signaling. Partial release of the antiangiogenic ligand in a reactive oxygen species-rich environment is possible as per our observation to inhibit both NF-κB and VEGFR2 by the complexes. The complexes are nontoxic to zebrafish embryos up to 50 μM, but the ligands show strong in vivo antiangiogenic activity at 3 μM during embryonic growth in Tg(fli1:GFP) zebrafish but no visible effect on the adult phase.

Indole-containing pharmaceuticals: targets, pharmacological activities, and SAR studies

Indole is a prestigious heterocyclic skeleton widely found in both naturally-occurring and biologically-active compounds. Pharmaceutical agents containing an indole skeleton in their framework possess a wide range of pharmacological properties, including antiviral, antitumor, analgesic, and other therapeutic activities, and many indole-containing drugs have been proven to have excellent pharmacokinetic and pharmacological effects. Over the past few decades, the FDA has approved over 40 indole-containing drugs for the treatment of various clinical conditions, and the development of indole-related drugs has attracted significant attention from medicinal chemists. This review aims to provide an overview of all the approved drugs that contain an indole nucleus, focusing on their targets, pharmacological activities, and SAR studies.

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.

Development of Platinum Complexes for Tumor Chemoimmunotherapy

Platinum complexes are potential antitumor drugs in chemotherapy. Their impact on tumor treatment could be greatly strengthened by combining with immunotherapy. Increasing evidences indicate that the antitumor activity of platinum complexes is not limited to chemical killing effects, but also extends to immunomodulatory actions. This review introduced the general concept of chemoimmunotherapy and summarized the progress of platinum complexes as chemoimmunotherapeutic agents in recent years. Platinum complexes could be developed into inducers of immunogenic cell death, blockers of immune checkpoint, regulators of immune signaling pathway, and modulators of tumor immune microenvironment, etc. The synergy between chemotherapeutic and immunomodulatory effects reinforces the antitumor activity of platinum complexes, and helps them circumvent the drug resistance and systemic toxicity. The exploration of platinum complexes for chemoimmunotherapy may create new opportunities to revive the discovery of metal anticancer drugs.

Current Status of Novel Multifunctional Targeted Pt(IV) Compounds and Their Reductive Release Properties

Platinum-based drugs are widely used in chemotherapy for various types of cancer and are considered crucial. Tetravalent platinum (Pt(IV)) compounds have gained significant attention and have been extensively researched among these drugs. Traditionally, Pt(IV) compounds are reduced to divalent platinum (Pt(II)) after entering cells, causing DNA lesions and exhibiting their anti-tumor effect. However, the available evidence indicates that some Pt(IV) derivatives may differ from the traditional mechanism and exert their anti-tumor effect through their overall structure. This review primarily focuses on the existing literature regarding targeted Pt(II) and Pt(IV) compounds, with a specific emphasis on their in vivo mode of action and the properties of reduction release in multifunctional Pt(IV) compounds. This review provides a comprehensive summary of the design and synthesis strategies employed for Pt(II) derivatives that selectively target various enzymes (glucose receptor, folate, telomerase, etc.) or substances (mitochondria, oleic acid, etc.). Furthermore, it thoroughly examines and summarizes the rational design, anti-tumor mechanism of action, and reductive release capacity of novel multifunctional Pt(IV) compounds, such as those targeting p53-MDM2, COX-2, lipid metabolism, dual drugs, and drug delivery systems. Finally, this review aims to provide theoretical support for the rational design and development of new targeted Pt(IV) compounds.

Novel Pt(IV) prodrug self-assembled nanoparticles with enhanced blood circulation stability and improved antitumor capacity of oxaliplatin for cancer therapy

Pt(IV) compounds are regarded as prodrugs of active Pt(II) drugs (i.e. cisplatin, carboplatin, and oxaliplatin) and burgeoned as the most ideal candidates to substitute Pt(II) anticancer drugs with severe side effects. Nanoparticle drug delivery systems have been widely introduced to deliver Pt(IV) prodrugs more effectively and safely to tumors, but clinical outcomes were unpredictable owing to limited in vivo pharmacokinetics understanding. Herein, a novel Pt(IV) prodrug of oxaliplatin(OXA) was synthesized and prepared as self-assembled micellar nanoparticles(PEG-OXA NPs). In vitro, PEG-OXA NPs rapidly released biologically active OXA within 5 min in tumor cells while remaining extremely stable in whole blood or plasma. Importantly, the pharmacokinetic results showed that the AUC_0-∞, and t_1/2 values of PEG-OXA NPs were 1994 ± 117 h·µg/mL and 3.28 ± 0.28 h, respectively, which were much higher than that of free OXA solution (2.03 ± 0.55 h·µg/mL and 0.16 ± 0.07 h), indicating the longer drug circulation of PEG-OXA NPs in vivo. The altered pharmacokinetic behavior of PEG-OXA NPs remarkably contributed to improve antitumor efficacy, decrease systemic toxicity and increase tumor growth inhibition compared to free OXA. These findings establish that PEG-OXA NPs have the potential to offer a desirable self-delivery platform of platinum drugs for anticancer therapeutics.

Ligustrazine-Derived Chalcones-Modified Platinum(IV) Complexes Intervene in Cisplatin Resistance in Pancreatic Cancer through Ferroptosis and Apoptosis

Developing multitarget platinum(IV) prodrugs is an important strategy to attenuate cisplatin (CDDP) resistance in tandem with reduced toxicity. Herein, six novel ligustrazine-derived chalcones-modified platinum(IV) complexes were synthesized and evaluated for their anti-proliferative activities. Among them, 16a displayed higher cytotoxicity toward the tested cancer cell lines and lower cytotoxicity toward the human normal cells than CDDP or the combined group. Mechanistic studies revealed that 16a efficiently induced DNA damage and initiated a mitochondria-dependent apoptosis pathway. Besides, 16a significantly triggered ferroptosis by down-regulating expression levels of nuclear factor erythroid 2-related factor 2, glutathione peroxidase 4, and solute carrier family 7 member 11. Further, 16a obtained superior in vivo anti-tumor efficiency than CDDP in CDDP-resistant pancreatic cancer xenograft models but showed no significant side effects. In summary, our study suggested that 16a acts via a different anti-cancer mechanistic pathway than CDDP and may therefore encompass a novel practical strategy for cancer treatment.

Pyrenebutyrate Pt(IV) Complexes with Nanomolar Anticancer Activity

Research on platinum-based anticancer drugs continuously strives to develop new non-classical platinum complexes. Pt(IV) prodrugs are the most promising, and their activation-by-reduction mechanism of action is being explored as a prospect for higher selectivity and efficiency. Herein, we present the anticancer potency and chemical reactivity of Pt(IV) complexes formed by linking pyrene butyric acid with cisplatin. The results from cytotoxicity screening on 10 types of cancer cell lines and non-malignant cells (HEK-293) indicated IC50 values as low as 50-70 nM for the monosubstituted Pt(IV) complex against leukemia cell lines (HL-60 and SKW3) and a cisplatin-resistant derivative (HL-60/CDDP). Interestingly, the bis-substituted complex is virtually non-toxic to both healthy and cancerous cells of adherent types. Nevertheless, it shows high cytotoxicity against multidrug-resistant derivatives HL-60/CDDP and HL-60/Dox. The reactivity of the complexes with biological reductants was monitored by the NMR method. Furthermore, the platinum uptake by the treated cells was examined on two types of cellular cultures: adherent and suspension growing, and proteome profiling was conducted to track expression changes of key apoptosis-related proteins in HL-60 cells. The general conclusion points to a possible cytoskeletal entrapment of the bulkier bis-pyrene complex that could be limiting its cytotoxicity to adherent cells, both cancerous and healthy ones.

Advances of antitumor drug discovery in traditional Chinese medicine and natural active products by using multi-active components combination

The antitumor efficacy of Chinese herbal medicines has been widely recognized. Leading compounds such as sterols, glycosides, flavonoids, alkaloids, terpenoids, phenylpropanoids, and polyketides constitute their complex active components. The antitumor monomers derived from Chinese medicine possess an attractive anticancer activity. However, their use was limited by low bioavailability, significant toxicity, and side effects, hindering their clinical applications. Recently, new chemical entities have been designed and synthesized by combining natural drugs with other small drug molecules or active moieties to improve the antitumor activity and selectivity, and reduce side effects. Such a novel conjugated drug that can interact with several vital biological targets in cells may have a more significant or synergistic anticancer activity than a single-molecule drug. In addition, antitumor conjugates could be obtained by combining pharmacophores containing two or more known drugs or leading compounds. Based on these studies, the new drug research and development could be greatly shortened. This study reviews the research progress of conjugates with antitumor activity based on Chinese herbal medicine. It is expected to serve as a valuable reference to antitumor drug research and clinical application of traditional Chinese medicine.

Novel 4-Amino-Quinazoline Moieties Ligated Platinum(IV) Prodrugs Overcome Cisplatin Resistance in EGFRWT Human Lung Cancer

Developing bioactive axial ligands ligated platinum(IV) complexes with advantages over monotherapy and drug combinations is an efficient strategy to ameliorate the clinical defects of platinum(II) drugs. In this article, a series of 4-amino-quinazoline moieties (privileged pharmacophores of well-studied EGFR inhhibitors) ligated platinum(IV) were synthesized and evaluated for their anticancer activities. Among the complex, 17b demonstrated higher cytotoxicity against the tested lung cancer cells (including CDDP-resistant A549/CDDP cells) while lower cytotoxicity toward human normal cells than Oxaliplatin (Oxa) or cisplatin (CDDP). Mechanistic investigation demonstrated that the enhanced intracellular uptake of 17b efficiently elevated the of reactive oxygen species levels by 6.1 times more than Oxa. Detailed mechanisms of overcoming CDDP resistance revealed that 17b significantly induced apoptosis via inducing severe DNA damage, disturbing mitochondrial transmembrane potentials, efficiently disturbing EGFR-PI3K-Akt signaling transduction and activating a mitochondria-dependent apoptosis pathway. Besides, 17b significantly inhibited migration and invasion in A549/CDDP cells. In vivo tests exhibited that 17b obtained superior antitumor effect and attenuated systemic toxicity in A549/CDDP xenografts. All these results emphasized that the antitumor action of 17b differed from that of. classical platinum(II) drugs and provided a novel practical method to overcome CDDP resistance in lung cancer.

Dual-target platinum(IV) complexes reverse cisplatin resistance in triple negative breast via inhibiting poly(ADP-ribose) polymerase (PARP-1) and enhancing DNA damage

Platinum(II)-based drugs play an important role in many chemotherapeutic protocols, but their further clinical applications are hindered by the development of drug resistance and serious side effects. Therefore, to reverse cisplatin (CDDP) resistance in tandem with reduced side effects, nine novel platinum(IV) complexes modified with key pharmacophore of Olaparib were synthesized and evaluated for biological activities. Among them, the optimal complex 8-2 showed good inhibitory activity against PARP-1 and superior anticancer effects over CDDP on parental (MDA-MB-231, IC₅₀ = 1.13 μM) and CDDP -resistant triple-negative breast cancer (TNBC) cell line (MDA-MB-231/CDDP, IC₅₀ = 1.72 μM). Detailed mechanisms revealed that compared with Olaparib and CDDP, the enhanced intracellular accumulation of 8-2 could efficiently reverse CDDP resistance in MDA-MB-231/CDDP cells via inhibiting DNA repair-associated mechanisms, enhancing DNA damage, and activating mitochondrion-dependent apoptosis pathway. Furthermore, 8-2 obtained higher tumor growth inhibition rate (64.1 %) than CDDP (26.5 %) in MDA-MB-231/CDDP xenografts, but it did not induce significant toxicity in vivo and in intro, making it a potential drug candidate for the treatment of TNBC.

Highly potent Platinum(IV) complexes with multiple-bond ligands targeting mitochondria to overcome cisplatin resistance

The efficacy and resistance of cisplatin-based compounds are very intractable problems at present. This study reports a series of platinum(IV) compounds containing multiple-bond ligands, which exhibited better tumor cell inhibitory activity and antiproliferative and anti-metastasis activities than cisplatin. The meta-substituted compounds 2 and 5 were particularly excellent. Further research showed that compounds 2 and 5 possessed appropriate reduction potential and performed significantly better than cisplatin in cellular uptake, reactive oxygen species response, the up-regulation of apoptosis and DNA lesion-related genes, and drug-resistant cell activity. The title compounds exhibited better antitumor potential and fewer side effects than cisplatin in vivo. Multiple-bond ligands were introduced into cisplatin to form the title compounds in this study, which not only enhanced their absorption and overcame drug resistance but also demonstrated the potential to target mitochondria and inhibit the detoxification of tumor cells.

Research Progress on Bioactive Metal Complexes against ER-Positive Advanced Breast Cancer

Breast cancer is the most prevalent cancer in women and represents a serious disease that is harmful to life and health. In 1977, with the approval of tamoxifen, endocrine therapy has become the main clinical treatment for ER-positive (ER+) breast cancer. Although patients initially respond well to endocrine therapies, drug resistance often emerges and side effects can be challenging. To overcome drug resistance, the exploration for new drugs is a priority. Metal complexes have demonstrated significant antitumor activities, and platinum complexes are widely used in the clinic against various cancers, including breast cancer. In this Perspective, the first section describes the classification and mechanism of endocrine therapy drugs for ER+ breast cancer, and the second section summarizes research since 2000 into metal complexes with activity toward ER+ breast cancer. Finally, we discuss the opportunities, challenges, and future directions for metal complexes in the treatment of ER+ breast cancer.

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.

Long-acting response of COX-2-mediated metastasis inhibition by oxaliplatin-based CP-L-OHP

Among four oxaliplatin-based Pt(iv) complexes, CP-L-OHP significantly delayed BGC-823 cell metastasis via long-acting inhibition of COX-2.

Targeting ROS-AMPK pathway by multiaction Platinum(IV) prodrugs containing hypolipidemic drug bezafibrate

Alterations in lipid metabolism, commonly disregarded in the past, have been accepted as a hallmark for cancer. Exploring cancer therapeutics that interrupt the lipid metabolic pathways by monotherapy or combination with conventional chemotherapy or immunotherapy is of great importance. Here we modified cisplatin with an FDA-approved hypolipidemic drug, bezafibrate (BEZ), via the well-established Pt(IV) strategy, affording two multi-functional Pt(IV) anticancer agents cis,cis,trans-[Pt(NH₃)₂Cl₂(BEZ)(OH)] (CB) and cis,cis,trans-[Pt(NH₃)₂Cl₂(BEZ)₂] (CP) (BEZ = bezafibrate). The Pt(IV) prodrug CB exhibited an enhanced anticancer activity up to 187-fold greater than the clinical anticancer drug cisplatin. Both CB and CP had less toxicity to normal cells, showing higher efficacies and superior therapeutic indexes than cisplatin. Mechanism studies revealed that the bezafibrate-conjugated Pt(IV) complex CB, as a representative, could massively accumulate in A549 cells and genomic DNA, induce DNA damage, elevate intracellular ROS levels, perturb mitochondrial transmembrane potentials, activate the cellular metabolic sensor AMPK, and result in profound proliferation inhibition and apoptosis. Further cellular data also provided evidence that phosphorylation of AMPK, as a metabolic sensor, could suppress the downstream HMGB1, NF-κB, and VEGFA, which may contribute to the inhibition of angiogenesis and metastasis. Our study suggests that the antitumor action of CB and CP mechanistically distinct from the conventional platinum drugs and that functionalizing platinum-based agents with lipid-modulating agents may represent a novel practical strategy for cancer treatment.

A comprehensive overview of β-carbolines and its derivatives as anticancer agents

β-Carboline alkaloids are a family of natural and synthetic products with structural diversity and outstanding antitumor activities. This review summarizes research developments of β-carboline and its derivatives as anticancer agents, which focused on both natural and synthetic monomers as well as dimers. In addition, the structure-activity relationship (SAR) analysis of β-carboline monomers and dimers are summarized and mechanism of action of β-carboline and its derivatives are also presented. A few possible research directions, suggestions and clues for future work on the development of novel β-carboline-based anticancer agents with improved expected activities and lesser toxicity are also provided.

Selective and effective anticancer agents: Synthesis, biological evaluation and structure-activity relationships of novel carbazole derivatives

Carbazole alkaloids is an important class of natural products with diverse biological functions. So, the aim of this article is to explore new chemical entities containing carbazole scaffold as potential novel cytotoxic agents based on our developed three-component indole-to-carbazole reaction. Two series of carbazole derivatives were designed and synthesized, and their in vitro cytotoxic activities against three cell lines (A875, HepG2, and MARC145) were evaluated. The results indicated that some of these carbazole derivatives exhibited significantly good cytotoxic activities against tested cell lines compared with the control 5-fluorouracil (5-FU). Especially, carbazole acylhydrazone compounds 7g and 7p displayed high inhibitory activity on cancer cells, but almost no activity on normal cells. Further analysis of induced apoptosis for potential compounds indicated that the potential antitumor agents induced cell death in A875 cells at least partly (initially) by apoptosis, which might be used as promising lead scaffold for discovery of novel carbazole-type cytotoxic agents.

Novel Pt(IV) complexes to overcome multidrug resistance in gastric cancer by targeting P-glycoprotein

Systematic toxicity and drug resistance significantly limited FDA-approved platinum drugs for further clinical applications. In order to reverse the resistance (MDR) and enhance their anticancer efficiency, four Pt(IV) complexes (12-15) conjugating with P-glycoprotein (P-gp) inhibitors were designed and synthesized. Among them, complex 14 (IC₅₀ = 3.37 μM) efficiently reversed cisplatin resistance in SGC-7901/CDDP cell line and increased selectivity index (6.9) against normal HL-7702 cell line. Detailed mechanisms in SGC-7901/CDDP cells assays revealed that complex 14 efficiently induced apoptosis via down-regulating expression of P-gp for enhanced intracellular uptake of platinum, arrested cells at G2/M phase, induced DNA damage and initiated mitochondrial apoptosis pathway. Further in vivo studies demonstrated that the enhanced accumulation of complex 14 contributed to tumor inhibition of 75.6% in SGC-7901/CDDP xenografts, which was much higher than cisplatin (25.9%) and oxaliplatin (43%). Moreover, the low systematic toxicity made 14 a potential novel P-gp-mediated MDR modulator.