Multiaction Platinum(IV) Prodrug Containing Thymidylate Synthase Inhibitor and Metabolic Modifier against Triple-Negative Breast Cancer

Platinum(IV)-Gold(I) Agents with Promising Anticancer Activity: Selected Studies in 2D and 3D Triple-Negative Breast Cancer Models

New heterometallic binuclear and trinuclear platinum(IV)-gold(I) compounds of the type [Pt(L)n Cl2 (OH){(OOC-4-C6 H4 -PPh2 )AuCl}x ] (L=NH3 , n=2; x=1, 2; L=diaminocyclohexane, DACH, n=1; x=2) are described. These compounds are cytotoxic and selective against a small panel of renal, bladder, ovarian, and breast cancer cell lines. We selected a trinuclear PtAu2 compound containing the PtIV core based on oxaliplatin, to further investigate its cell-death pathway, cell and organelle uptake and anticancer effects against the triple-negative breast cancer (TNBC) MDA-MB-231 cell line. This compound induces apoptosis and accumulates mainly in the nucleus and mitochondria. It also exerts remarkable antimigratory and antiangiogenic properties, and has a potent cytotoxic effect against TNBC 3D spheroids. Trinuclear compounds do not seem to display relevant interactions with calf thymus (CT) DNA and plasmid (pBR322) even in the presence of reducing agents, but inhibit pro-angiogenic enzyme thioredoxin reductase (TrxR) in TNBC cells.

Study on the Multimodal Anticancer Mechanism of Ru(II)/Ir(III) Complexes Bearing a Poly(ADP-ribose) Polymerase 1 Inhibitor

A series of novel ruthenium(II) and iridium(III) complexes (Ru1-Ru3 and Ir1-Ir3) with different ancillary ligands and a PARP-1-inhibitory chelating ligand 2-(2,3-dibromo-4,5-dimethoxybenzylidene)hydrazine-1-carbothioamide (L1) were designed and prepared. The target complexes were structurally characterized by NMR and ESI-MS techniques. Among them, the crystal and molecular structures of Ir1 and Ir2 were also determined by X-ray crystallography. These complexes retained the PARP-1 enzyme inhibitory effect of L1 and showed potent antiproliferative activity on the tested cancer cell lines. The ruthenium(II) complexes Ru1-Ru3 were found to be more cytotoxic than the iridium(III) complexes Ir1-Ir3. Further investigations revealed that the most active complex Ru3 induced apoptosis in MCF-7 cells by multiple modes, inclusive of inducing DNA damage, suppressing DNA damage repair, disturbing cell cycle distribution, decreasing the mitochondrial membrane potential, and increasing the intracellular reactive oxygen species levels.

Deciphering the Mysterious Relationship between the Cross-Pathogenetic Mechanisms of Neurodegenerative and Oncological Diseases

The relationship between oncological pathologies and neurodegenerative disorders is extremely complex and is a topic of concern among a growing number of researchers around the world. In recent years, convincing scientific evidence has accumulated that indicates the contribution of a number of etiological factors and pathophysiological processes to the pathogenesis of these two fundamentally different diseases, thus demonstrating an intriguing relationship between oncology and neurodegeneration. In this review, we establish the general links between three intersecting aspects of oncological pathologies and neurodegenerative disorders, i.e., oxidative stress, epigenetic dysregulation, and metabolic dysfunction, examining each process in detail to establish an unusual epidemiological relationship. We also focus on reviewing the current trends in the research and the clinical application of the most promising chemical structures and therapeutic platforms that have a modulating effect on the above processes. Thus, our comprehensive analysis of the set of molecular determinants that have obvious cross-functional pathways in the pathogenesis of oncological and neurodegenerative diseases can help in the creation of advanced diagnostic tools and in the development of innovative pharmacological strategies.

Therapeutic Potential of Tumor Metabolic Reprogramming in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, with clinical features of high metastatic potential, susceptibility to relapse, and poor prognosis. TNBC lacks the expression of the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). It is characterized by genomic and transcriptional heterogeneity and a tumor microenvironment (TME) with the presence of high levels of stromal tumor-infiltrating lymphocytes (TILs), immunogenicity, and an important immunosuppressive landscape. Recent evidence suggests that metabolic changes in the TME play a key role in molding tumor development by impacting the stromal and immune cell fractions, TME composition, and activation. Hence, a complex inter-talk between metabolic and TME signaling in TNBC exists, highlighting the possibility of uncovering and investigating novel therapeutic targets. A better understanding of the interaction between the TME and tumor cells, and the underlying molecular mechanisms of cell-cell communication signaling, may uncover additional targets for better therapeutic strategies in TNBC treatment. In this review, we aim to discuss the mechanisms in tumor metabolic reprogramming, linking these changes to potential targetable molecular mechanisms to generate new, physical science-inspired clinical translational insights for the cure of TNBC.

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.

Hitting Multiple Cellular Targets in Triple-Negative Breast Cancer Using Dual-Action Cisplatin(IV) Prodrugs for Safer Synergistic Chemotherapy

Triple-negative breast cancer (TNBC) cells show improved sensitivity for cisplatin therapy due to their defective DNA damage repair system. However, the clinical utilization of cisplatin is limited by dose-dependent systemic toxicities and chemoresistance. Cisplatin Pt(IV) derivatives having kinetically inert octahedral geometry provide an effective strategy to overcome these limitations. Upon cellular reduction, these derivatives release cisplatin and axial ligands, acting as dual-action prodrugs. Hereby, we have developed three cisplatin(IV) conjugates using distinct bioactive axial moieties (valproate, tocopherol, and chlorambucil), which can synergistically complement cisplatin activity and attack multiple cellular targets. The designed derivatives showcased enhanced antiproliferative activity and improved therapeutic synergism along with a noteworthy cisplatin dose reduction index in a panel of six cancer cells. These Pt(IV) derivatives remarkably improved cellular drug uptake and showed lower dependency on copper transporter 1 (Ctr1) for uptake than cisplatin. The results of enhanced in vitro activity were well corroborated by in vivo efficacy testing in the 4T1 cell-based TNBC model, showcasing ∼2-7-folds higher tumor volume reduction for Pt(IV) derivatives than cisplatin. In addition, the designed derivatives significantly reduced the nephrotoxicity risk involved in cisplatin therapy, indicated by systemic toxicity biomarkers and organ histopathology. The results indicated that cisplatin(IV) derivatives could open new avenues for safer synergistic chemotherapy in TNBC.

Multifunctional platinum(IV) complex bearing HDAC inhibitor and biotin moiety exhibits prominent cytotoxicity and tumor-targeting ability

Despite the wide clinical use of platinum drugs in cancer treatment, their severe side effects and lack of tumor selectivity seriously limit their further clinical application. To address the limitations of the current platinum drugs, herein a multifunctional platinum(IV) compound 1 containing a histone deacetylase (HDAC) inhibitor (4-phenylbutyric acid, 4-PBA) and a tumor-targeting group (biotin) has been designed and prepared. An in vitro cytotoxicity study indicated that compound 1 exhibits comparable or superior cytotoxicity to cisplatin against the tested cancer cell lines, but greatly reduced toxicity in human normal liver LO2 cells, implying the potential tumor-targeting ability of compound 1. Molecular docking results indicate that compound 1 can effectively interact with a biotin-specific receptor (streptavidin) through its biotin moiety, enabling potential tumor-targeting capability. Further studies indicated that compound 1's cytotoxicity stems from inducing DNA damage via the mitochondrial apoptotic pathway and inhibiting HDACs. Consequently, this compound can not only take advantage of the tumor selectively of biotin to improve its tumor-targeting ability but also strengthen its anticancer activity via simultaneously targeting DNA and HDACs.

Dithiocarbazate-FeIII, -CoIII, -NiII, and -ZnII Complexes: Design, Synthesis, Structure, and Anticancer Evaluation

Non-platinum-metal complexes show great potential as anticancer agents. Herein, a series of dithiocarbazate non-Pt-metal complexes, including [Fe^III(L)₂]·Cl·2H₂O 1, [Co^III(L)₂]·NO₃·2.5H₂O 2, [Ni^II(L)₂] 3, and [Zn^II(L)₂] 4, have been designed and evaluated for their efficacy as antineoplastic agents. Among them, complex 2 exhibited higher anticancer efficacy than complexes 1, 3, 4, and cisplatin against several cancer cell lines. Hemolysis assays revealed that complex 2 showed comparable hemolysis with cisplatin. In vivo anticancer evaluations showed that complex 2 could retard tumor xenograft growth effectively with low systemic toxicity. Further studies revealed that complex 2 suppressed cancer cells by triggering multiple mechanisms involving the simultaneous inhibition of mitochondria and glycolytic bioenergetics. Overall, our study provides new insights into the anticancer mechanism of Co complexes, which can be used as a good strategy to overcome the flexibility of cancer cells to chemotherapy adaptation.

Metallodrugs in cancer nanomedicine

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

Ptxplatin: a multifunctional Pt(iv) antitumor prodrug

Ptxplatin, comprising paclitaxel and cisplatin, intervened in several cellular processes including the p53 apoptosis pathway, mitochondrial damage and ER stress to kill cancer cells.

Trifluoromethyl substitution enhances photoinduced activity against breast cancer cells but reduces ligand exchange in Ru(ii) complex

A series of five ruthenium complexes containing triphenyl phosphine groups known to enhance both cellular penetration and photoinduced ligand exchange, cis-[Ru(bpy)2(P(p-R-Ph)3)(CH3CN)]2+, where bpy = 2,2'-bipyridine and P(p-R-Ph)3 represent para-substituted triphenylphosphine ligands with R = -OCH3 (1), -CH3 (2) -H (3), -F (4), and -CF3 (5), were synthesized and characterized. The photolysis of 1-5 in water with visible light (λ irr ≥ 395 nm) results in the substitution of the coordinated acetonitrile with a solvent molecule, generating the corresponding aqua complex as the single photoproduct. A 3-fold variation in quantum yield was measured with 400 nm irradiation, Φ 400, where 1 is the most efficient with a Φ 400 = 0.076(2), and 5 the least photoactive complex, with Φ 400 = 0.026(2). This trend is unexpected based on the red-shifted metal-to-ligand charge transfer (MLCT) absorption of 1 as compared to that of 5, but can be correlated to the substituent Hammett para parameters and pK a values of the ancillary phosphine ligands. Complexes 1-5 are not toxic towards the triple negative breast cancer cell line MDA-MB-231 in the dark, but 3 and 5 are >4.2 and >19-fold more cytotoxic upon irradiation with blue light, respectively. A number of experiments point to apoptosis, and not to necrosis or necroptosis, as the mechanism of cell death by 5 upon irradiation. These findings provide a foundation for understanding the role of phosphine ligands on photoinduced ligand substitution and show the enhancement afforded by -CF3 groups on photochemotherapy, which will aid the future design of photocages for photochemotherapeutic drug delivery.

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.

Redirecting Cisplatin and Doxorubicin to Mitochondria Affords Highly Effective PlatinumIV Prodrug Against Triple Negative Breast Cancer

A mitochondria targeting dual-action platinum^IV prodrug exhibits high anticancer activity in triple negative breast cancer cells. The complex intervenes in several cellular processes including DNA damage, perturbation of mitochondrial bioenergetics and induction of necrosis to kill cancer cells.

Hetero-Bis-Conjugation of Bioactive Molecules to Half-Sandwich Ruthenium(II) and Iridium(III) Complexes Provides Synergic Effects in Cancer Cell Cytotoxicity

Four bipyridine-type ligands variably derivatized with two bioactive groups (taken from ethacrynic acid, flurbiprofen, biotin, and benzylpenicillin) were prepared via sequential esterification steps from commercial 2,2'-bipyridine-4,4'-dicarboxylic acid and subsequently coordinated to ruthenium(II) p-cymene and iridium(III) pentamethylcyclopentadienyl scaffolds. The resulting complexes were isolated as nitrate salts in high yields and fully characterized by analytical and spectroscopic methods. NMR and MS studies in aqueous solution and in cell culture medium highlighted a substantial stability of ligand coordination and a slow release of the bioactive fragments in the latter case. The complexes were assessed for their antiproliferative activity on four cancer cell lines, showing cytotoxicity to the low micromolar level (equipotent with cisplatin). Additional biological experiments revealed a multimodal mechanism of action of the investigated compounds, involving DNA metalation and enzyme inhibition. Synergic effects provided by specific combinations of metal and bioactive fragments were identified, pointing toward an optimal ethacrynic acid/flurbiprofen combination for both Ru(II) and Ir(III) complexes.

Metabolic changes in triple negative breast cancer-focus on aerobic glycolysis

Among breast cancer subtypes, the triple negative breast cancer (TNBC) has the worst prognosis. In absence of any permitted targeted therapy, standard chemotherapy is the mainstay for TNBC treatment. Hence, there is a crucial need to identify potential druggable targets in TNBCs for its effective treatment. In recent times, metabolic reprogramming has emerged as cancer cells hallmark, wherein cancer cells display discrete metabolic phenotypes to fuel cell progression and metastasis. Altered glycolysis is one such phenotype, in which even in oxygen abundance majority of cancer cells harvest considerable amount of energy through elevated glycolytic-flux. In the present review, we attempt to summarize the role of key glycolytic enzymes i.e. HK, Hexokinase; PFK, Phosphofructokinase; PKM2, Pyruvate kinase isozyme type 2; and LDH, Lactate dehydrogenase in TNBCs, and possible therapeutic options presently available.

Platinum(IV) complexes conjugated with chalcone analogs as dual targeting anticancer agents: In vitro and in vivo studies

For the sake to develop novel platinum(IV) complexes to reverse cisplatin (CDDP) resistence, four multifunctional platinum(IV) prodrugs via conjugating chalcones with the related platinum(IV) complexes derived from cisplatin were designed and evaluated for anti-tumor actyivities in vitro and in vivo. Among them, complex 9 exhibited excellent anticancer activities in vitro with IC₅₀ values at the submicromolar level against the tested human cancer cells, whereas showed low cytotoxicity towards human normal liver cells HL-7702. Further mechanistic studies indicated that complex 9 induced G2/M phase arrest and apoptosis in A549 cells, which was associated with a collapse of the mitochondrial membrane potential (MMP), alterations in the expression of some apoptosis-related proteins, and enhanced level of the intracellular reactive oxygen species (ROS). More importantly, complex 9 significantly suppressed the tumor growth in the A549 xenograft model without obvious hints of toxicity.