Non-Platinum Metal Complexes as Potential Anti-Triple Negative Breast Cancer Agents

Pd2Spermine as an Alternative Therapeutics for Cisplatin-Resistant Triple-Negative Breast Cancer

Cisplatin (cDDP) resistance is a matter of concern in triple-negative breast cancer therapeutics. We measured the metabolic response of cDDP-sensitive (S) and -resistant (R) MDA-MB-231 cells to Pd2Spermine(Spm) (a possible alternative to cDDP) compared to cDDP to investigate (i) intrinsic response/resistance mechanisms and (ii) the potential cytotoxic role of Pd2Spm. Cell extracts were analyzed by untargeted nuclear magnetic resonance metabolomics, and cell media were analyzed for particular metabolites. CDDP-exposed S cells experienced enhanced antioxidant protection and small deviations in the tricarboxylic acid cycle (TCA), pyrimidine metabolism, and lipid oxidation (proposed cytotoxicity signature). R cells responded more strongly to cDDP, suggesting a resistance signature of activated TCA cycle, altered AMP/ADP/ATP and adenine/uracil fingerprints, and phospholipid biosynthesis (without significant antioxidant protection). Pd2Spm impacted more markedly on R/S cell metabolisms, inducing similarities to cDDP/S cells (probably reflecting high cytotoxicity) and strong additional effects indicative of amino acid depletion, membrane degradation, energy/nucleotide adaptations, and a possible beneficial intracellular γ-aminobutyrate/glutathione-mediated antioxidant mechanism.

G2/M-Phase-Inhibitory Mitochondrial-Depolarizing Re(I)/Ru(II)/Ir(III)-2,2'-Bipyrimidine-Based Heterobimetallic Luminescent Complexes: An Assessment of In Vitro Antiproliferative Activity and Bioimaging for Targeted Therapy toward Human TNBC Cells

Triple-negative breast cancer (TNBC) is an extremely vicious subtype of human breast cancer having the worst prognosis along with strong invasive and metastatic competency. Hence, it can easily invade into blood vessels, and presently, no targeted therapeutic approach is available to annihilate this type of cancer. Metal complexes have successfully stepped into the anticancer research and are now being applauded due to their anticancer potency after the discovery of cisplatin. Many of these metal complexes are also well recognized for their activity toward breast cancer. As the TNBC is a very dangerous subtype and has long been a challenging ailment to treat, we have intended to develop a few brand new mixed metallic Ru(II)/Ir(III)/Re(I)-2,2'-bipyrimidine complexes [L'Re2], [L'RuRe], and [L'IrRe] to abate the unbridled proliferation of TNBC cells. The potency of the complexes against TNBC cells has been justified using MDA-MB-468 TNBC cell lines where complex [L'IrRe] has displayed significant potency among all the three complexes with an IC₅₀ value of 24.12 μM. The complex [L'IrRe] has been competent to cause apoptosis of TNBC cells through inhibition of the G2/M phase in the cell cycle in association with a profuse amount of ROS generation and mitochondrial depolarization.

Preparation, cytotoxic activity and DNA interaction studies of new platinum(II) complexes with 1,10-phenanthroline and 5-alkyl-1,3,4-oxadiazol-2(3H)-thione derivatives

This work describes the synthesis, characterization and in vitro anticancer activity of two platinum(II) complexes of the type [Pt(L1)₂(1,10-phen)] 1 and [Pt(L2)₂(1,10-phen)] 2, where L1 = 5-heptyl-1,3,4-oxadiazole-2-(3H)-thione, L2 = 5-nonyl-1,3,4-oxadiazole-2-(3H)-thione and 1,10-phen = 1,10-phenanthroline. As to the structure of these complexes, the X-ray structural analysis of 1 indicates that the geometry around the platinum(II) ion is distorted square-planar, where two 5-alkyl-1,3,4-oxadiazol-2-thione derivatives coordinate a platinum(II) ion through the sulfur atom. A chelating bidentate phenanthroline molecule completes the coordination sphere. We tested these complexes in two breast cancer cell lines, namely, MCF-7 (a hormone responsive cancer cell) and MDA-MB-231 (triple negative breast cancer cell). In both cells, the most lipophilic platinum compound, complex 2, was more active than cisplatin, one of the most widely used anticancer drugs nowadays. DNA binding studies indicated that such complexes are able to bind to ct-DNA with K_b values of 10⁴ M^-1. According to data from dichroism circular and fluorescence spectroscopy, these complexes appear to bind to the DNA in a non-intercalative, probably via minor groove. Molecular docking followed by semiempirical simulations indicated that these complexes showed favorable interactions with the minor groove of the double helix of ct-DNA in an A-T rich region. Thereafter, flow cytometry analysis showed that complex 2 induced apoptosis and necrosis in MCF-7 cells.

Mitochondria-targeted half-sandwich iridium(iii)-Cp*-arylimidazophenanthroline complexes as antiproliferative and bioimaging agents against triple negative breast cancer cells MDA-MB-468

To reduce the side effects of marketed cancer drugs against triple negative breast cancer cells we have reported mitochondria targeting half-sandwich iridium(iii)-Cp*-arylimidazophenanthroline complexes for MDA-MB-468 cell therapy and diagnosis. Out of five Ir(iii) complexes (IrL1–IrL5), [iridium(iii)-Cp*-2-(naphthalen-1-yl)-1H-imidazo[4,5-f][1,10]phenanthroline]PF₆ (IrL1) has exhibited the best cytoselectivity against MDA-MB-468 cells compared to normal HaCaT cells along with excellent binding efficacy with DNA as well as serum albumin. The subcellular localization study of the complex revealed the localization of the compound in cytoplasm thereby pointing to a possible mitochondrial localization and consequent mitochondrial dysfunction via MMP alteration and ROS generation. Moreover, the IrL1 complex facilitated a substantial G₁ phase cell-cycle arrest of MDA-MB-468 cells at the highest tested concentration of 5 μM. The study verdicts support the prospective therapeutic potential of the IrL1 complex in the treatment and eradication of triple negative breast cancer cells. These results validate that these types of scaffolds will be fairly able to exert great potential for tumor diagnosis as well as therapy in the near future.

Mitochondria targeting half-sandwich Iridium(iii)-Cp*-arylimidazophenanthroline complexes have been developed for MDA-MB-468 cell therapy and diagnosis.

Anticancer activity of RAPTA-EA1 in triple-negative BRCA1 proficient breast cancer cells: single and combined treatment with the PARP inhibitor olaparib

RAPTA-EA1 is a promising glutathione transferase (GSTP-1) inhibitor that has previously been shown to inhibit the growth of various breast cancer cells. We studied the anticancer activity of RAPTA-EA1 on triple-negative BRCA1 competent breast cancer MDA-MB-231 cells. MDA-MB-231 cells are significantly more sensitive to RAPTA-EA1 than MCF-7 cells. Treatment reveals a higher degree of cytotoxicity than cisplatin against both cell lines. Ruthenium accumulation in MDA-MB-231 cells is mainly in the nuclear fraction (43%), followed by the cytoplasm (30%), and the mitochondria (27%). RAPTA-EA1 blocks cell growth at the G2/M phase, leading to nuclear condensation and cell death. The compound slightly inhibits DNA replication of the 3,426-bp fragment of the BRCA1 exon 11 of the cells, with approximately 0.6 lesion per the BRCA1 fragment. The expression of BRCA1 mRNA and its protein in the Ru-treated cells is curtailed by 50–80% compared to the untreated controls. Growth inhibition of the triple-negative BRCA1 wild-type MDA-MB-231 and the sporadic BRCA1 wild-type MCF-7 cells by olaparib (a poly [ADP-ribose] polymerase (PARP) inhibitor) is dose-dependent, with MDA-MB-231 cells being two-fold less susceptible to the drug than MCF-7 cells. Combining olaparib with RAPTA-EA1 results in a combination index (CI) of 0.78 (almost additive) in MDA-MB-231 cells and 0.24 (potent synergy) in the MCF-7 cells. The PARP inhibitor alone differently regulates the expression of BRCA1 mRNA in both cell lines, whereas the olaparib-RAPTA-EA1 combination induces overexpression of BRCA1 mRNA in these cells. However, the expression level of the BRCA1 protein is dramatically reduced after treatment with the combined inhibitors, compared with the untreated controls. This observation highlights the cellular responses of triple-negative BRCA1 proficient breast cancer MDA-MB-231 cells to RAPTA-EA1 through BRCA1 inhibition and provides insights into alternative treatments for breast cancer.

Cytotoxicity, anti-tumor effects and structure-activity relationships of nickel and palladium S,C,S pincer complexes against double and triple-positive and triple-negative breast cancer (TNBC) cells

Triple-Negative Breast Cancer (TNBC) is a highly aggressive form of breast cancer. The high rate of metastasis associated with TNBC is attributed to its multidrug resistance, making the treatment of this metastatic condition difficult. The development of metal-based antitumor agents was launched with the discovery of cisplatin, followed by the development of related antitumor drugs such as carboplatin and oxaliplatin. Yet, the severe side effects of this approach represent a limitation for its clinical use. The current search for new metal-based antitumor agents possessing less severe side effects than these platinum-based complexes has focused on various complexes of nickel and palladium, the group 10 congeners of platinum. In this work, we have prepared a series of SCS-type pincer complexes of nickel and palladium featuring a stable meta-phenylene central moiety and two chelating but labile thioamide donor moieties at the peripheries of the ligand. We have demonstrated that the complexes in question, namely L1NiCl, L1NiBr, L1PdCl, L2PdCl, and L3PdCl, are active on the proliferation of estrogen-dependent breast tumor cells (MCF-7 and MC4L2) and triple-negative breast cancer (4 T1). Among the complexes studied, the palladium derivatives were found to be much safer anticancer agents than nickel counterparts; these were thus selected for further investigations for their effects on tumor cell adhesion and migration as well. The results of our studies show that palladium complexes are effective for inhibiting TNBC 4 T1 cells adhesion and migration. Finally, the HOMO and LUMO analysis was used to determine the reactivity and charge transfer within the compounds.

Exploring the Potential of Metallodrugs as Chemotherapeutics for Triple Negative Breast Cancer

This review focuses on studies of coordination and organometallic compounds as potential chemotherapeutics against triple negative breast cancer (TNBC) which has one of the poorest prognoses and worst survival rates from all breast cancer types. At present, chemotherapy is still the standard of care for TNBC since only one type of targeted therapy has been recently developed. References for metal-based compounds studied in TNBC cell lines will be listed, and those of metal-specific reviews, but a detailed overview will also be provided on compounds studied in vivo (mostly in mice models) and those compounds for which some preliminary mechanistic data was obtained (in TNBC cell lines and tumors) and/or for which bioactive ligands have been used. The main goal of this review is to highlight the most promising metal-based compounds with potential as chemotherapeutic agents in TNBC.

A review of nanotechnology-based approaches for breast cancer and triple-negative breast cancer

Breast cancer (BC) is one of the most prevalent cancers in women. Triple-negative breast cancer (TNBC) in which the three major receptors i.e. estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), are absent is known to express the most aggressive phenotype and increased metastasis which results in the development of resistance to chemotherapy. It offers various therapeutic advantages in treating BC and TNBC. Nanotechnology offers various unique characteristics such as small size (nanometric), active and passive targeting, and the ability to attach multiple targeting moieties, controlled release, and site-specific targeting. This review focuses on conventional drug therapies, recent treatment strategies, and unique therapeutic approaches available for BC and TNBC. The role of breast cancer stem cells in the recurrence of BC and TNBC has also been highlighted. Several chemotherapeutic agents delivered using nanocarriers such as polymeric nanoparticles/micelles, metallic/inorganic NPs, and lipid-based NPs (Liposome, solid-lipid nanoparticles (SLNs), and nanostructured lipid carriers (NLCs)), etc. with excellent responses in the treatment of BC/TNBC along with breast cancer stem cells have been discussed in details. Moreover, the application of nanomedicine including CRISPR nanoparticle, exosomes for the treatment of BC/TNBC and other molecular targets available such as poly (ADP-ribose) polymerase (PARP), epidermal growth factor receptor (EGFR), Vascular endothelial growth factor (VEGF), etc. for further exploration have also been discussed.

Two Sides to the Same Coin-Cytotoxicity vs. Potential Metastatic Activity of AgNPs Relative to Triple-Negative Human Breast Cancer MDA-MB-436 Cells

Silver nanoparticles (AgNPs) are used in many fields of industry and medicine. Despite the well-established antimicrobial activity, AgNPs are foreseen to be used as anticancer drugs due to the unusual feature-inability to induce drug resistance in cancer cells. The aim of the study was to assess biological activity of AgNPs against MDA-MB-436 cells. The cells were derived from triple-negative breast cancer, a type of breast cancer with poor prognosis and is particularly difficult to cure. AgNPs were toxic to MDA-MB-436 cells and the probable mechanism of toxicity was the induction of oxidative stress. These promising effects, giving the opportunity to use AgNPs as an anti-cancer agent should, however, be treated with caution in the light of further results. Namely, the treatment of MDA-MB-436 cells with AgNPs was associated with the increased secretion of several cytokines and chemokines, which were important in breast cancer metastasis. Finally, changes in the actin cytoskeleton of MDA-MB-436 cells under the influence of AgNPs treatment were also observed.

Copper(ii) complexes with 2,2′:6′,2′′-terpyridine, 2,6-di(thiazol-2-yl)pyridine and 2,6-di(pyrazin-2-yl)pyridine substituted with quinolines. Synthesis, structure, antiproliferative activity, and catalytic activity in the oxidation of alkanes and alcohols with peroxides

The toxicity of six new Cu(ii) complexes was evaluated in cancer derived cell lines. A model of competitive interaction of hydroxyl radicals with CH₃CN and RH in the catalyst cavity has been proposed.

Nuclear localization of dirhodium(ii) complexes in breast cancer cells by X-ray fluorescence microscopy

X-ray fluorescence microscopy confirms the necessity of vacant axial sites in dirhodium(ii) carboxylates for their cellular uptake and cytotoxicity.