Proliferative and anti-proliferative effects of titanium- and iron-based metallocene anti-cancer drugs

In previous work we have found that Cp₂TiCl₂ and its corresponding derivative of tamoxifen, Titanocene tamoxifen, show an unexpected proliferative effect on hormone dependent breast cancer cells MCF-7. In order to check if this behavior is a general trend for titanocene derivatives we have tested two other titanocene derivatives, Titanocene Y and Titanocene K, on this cell line. Interestingly, these two titanocene complexes behave in a totally different manner. Titanocene K is highly proliferative on MCF-7 cells even at low concentrations (0.5 μM), thus behave almost similarly to Cp₂TiCl₂. This proliferative effect is also observed in the presence of bovine serum albumin (BSA). In contrast, Titanocene Y alone has almost no effect on MCF-7 at a concentration of 10 μM, but exhibits a significant dose dependent cytotoxic effect of up to 50% when incubated with BSA (20-50 μg/mL). This confirms the crucial role played by the binding to serum proteins in the expression of the in vivo, cytotoxicity of the titanocene complexes. From the hydridolithiation reaction of 6-p-anisylfulvene with LiBEt₃H followed by transmetallation with iron dichloride [bis-[(p-methoxy-benzyl)cyclopentadienyl]iron(II)] (Ferrocene Y) was synthesised. This complex, which was characterised by single crystal X-ray diffraction, contains the robust ferrocenyl unit instead of Ti associated with easily leaving groups such as chlorine and shows only a modest cytotoxicity against MCF-7 or MDA-MB-231 cells.     

Organometallic diphenols: The importance of the organometallic moiety on the expression of a cytotoxic effect on breast cancer cells

We have recently reported that the ferrocenyl diphenol compound 1,1-di(4-hydroxyphenyl)-2-ferrocenyl-but-1-ene 1 exhibited strong in vitro anti-proliferative effects on both hormone dependent (MCF7, IC₅₀ = 0.7 μM) and hormone independent (MDA-MB231, IC₅₀ = 0.6 μM) breast cancer cells. In order to assess the importance of the ferrocenyl motif, we have prepared a series of analogs using the organometallic fragments (η⁵-C₅H₄)Cp^∗Fe (7), ((η⁵-C₅H₄)(CH₃)₂phospholyl)Fe (9), (η⁵-C₅H₄)CpRu (10), (η⁵-C₅H₄)Re(CO)₃ (11), and (η⁵-C₅H₄)Mn(CO)₃ (12), and the chlorinated ferrocenyl derivative 1,1-di(4-hydroxyphenyl)-2-ferrocenyl-4-chloro-but-1-ene (4). The nature of the organometallic moiety had a strong influence on estrogen receptor alpha (ERα) recognition, with relative binding affinity (RBA) values ranging from 0.55% to 10.8%. The second isoform of the estrogen receptor, ERβ, was better able to accommodate these compounds, with RBA values ranging from 8.9% to 17.1%. Molecular modeling studies suggest that the orientation of the compounds and their interactions with the residues of ERα and ERβ binding sites are very similar. A study on the MCF7 hormone dependent breast cancer cell line revealed an anti-proliferative effect for the ferrocenyl phenols 1 and 4, while the other compounds displayed either a proliferative effect (9-12), or no effect (7). The anti-proliferative effect of 1 and 4 is also evident in the MDA-MB231 hormone independent breast cancer cell line (IC₅₀(4) = 1 μM), and can be attributed to the cytotoxicity of these compounds, while the other compounds showed no effect on this cell line. The cytotoxicity of 1 and 4 may arise from electron delocalization in the radical cation in alkaline conditions, possibly resulting in a cytotoxic quinone methide formation, while the other complexes do not undergo the formation of this entity, as evidenced by the electrochemical results.     

Organometallic analogues of tamoxifen: Effect of the amino side-chain replacement by a carbonyl ferrocenyl moiety in hydroxytamoxifen

Since the widely prescribed selective estrogen receptor modulator (SERM) tamoxifen encounters growing cases of resistance in long-term treatments, alternative drugs with different therapeutic scopes have to be developed. Many investigators have modified the triphenylethylene scaffold, but very few have changed its amino side chain, essential for the antiestrogenic activity. For the first time, a lipophilic and stable organometallic entity, -OCH₂CO-[(η⁵-C₅H₄)FeCp], has replaced this key functional side chain, while keeping a good affinity for the estrogen receptor and an antiproliferative activity on cancer cells (MCF-7 and PC-3). Its mechanism of action is likely to be different from the antihormonal pathway followed by hydroxytamoxifen, and from the cytotoxicity observed for the ferrocifens.     

The synthesis, structural characterization and in vitro anti-cancer activity of novel N-(3-ferrocenyl-2-naphthoyl) dipeptide ethyl esters and novel N-(6-ferrocenyl-2-naphthoyl) dipeptide ethyl esters

N-(3-ferrocenyl-2-naphthoyl) dipeptide esters (5-7) and N-(6-ferrocenyl-2-naphthoyl) dipeptide esters (8-10) were prepared by coupling either 3-ferrocenylnaphthalene-2-carboxylic acid 2 or 6-ferrocenylnaphthalene-2-carboxylic acid 4 to the dipeptide ethyl esters GlyAla(OEt) (5, 8), AlaGly(OEt) (6, 9), and AlaAla(OEt) (7, 10) using the standard N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC), 1-hydroxybenzotriazole (HOBt) protocol. All the compounds were fully characterized using a combination of ¹H NMR, ¹³C NMR, DEPT-135 and ¹H-¹³C COSY (HMQC) spectroscopy, electrospray ionization mass spectrometry (ESI-MS) and cyclic voltammetry (CV). In vitro, the cytotoxic effects of compounds 5-10 show improvements over the corresponding N-(ferrocenyl)benzoyl derivatives, with IC₅₀ values against the H1299 lung cancer cells ranging from 1.2 μM to 8.0 μM. N-(6-ferrocenyl-2-naphthoyl)-glycine-l-alanine ethyl ester 8 was found to be the most active derivative of the naphthoyl series so far, displaying an IC₅₀ value of 1.3 ± 0.1 μM. This value is slightly lower than that found for the clinically employed anti-cancer drug cisplatin (IC₅₀ = 1.5 ± 0.1 μM against H1299).     

Cell cycle-dependent characterization of single MCF-7 breast cancer cells by 2-D CE

The composition of single MCF-7 breast cancer cells is characterized using 2-D CE. Individual MCF-7 cells were aspirated into a 30 mum inner diameter fused-silica capillary and lysed by contact with an SDS-containing buffer. Proteins and other primary amines were fluorescently labeled on-column using the fluorogenic dye 3-(2-furoyl)quinoline-2-carboxaldehyde. Labeled components were separated first according to molecular weight using capillary sieving electrophoresis (CSE) and then by MEKC. Analytes were detected in a sheath-flow cuvette using LIF. The expression profiles for MCF-7 cellular homogenate and a single MCF-7 cell are compared. As a proof-of-principle investigation, variation in expression was also compared within and between G1 and G2/M cell cycle phases for MCF-7 cells. Following their treatment with the viable nuclear stain Hoechst 33342, MCF-7 cells were sorted by flow cytometry on the basis of their ploidy. Sorted cells were then analyzed by 2-D CE. The degree of variability was >2.5 times larger between cells of different phases than between cells of the same phase. In typical 1 h 2-D CE separations using MCF-7 cells, over 100 components are resolved.     

Exploring the mechanism of Cremastra Appendiculata (SUANPANQI) against breast cancer by network pharmacology and molecular docking

BackgroundSUANPANQI, the pseudo phosphorous stem of Cremastra appendiculata, is one of the most well-known traditional Chinese medicine, which has been shown to inhibit tumorigenesis in various human cancers. However, the underlying mechanism of SUANPANQI treatment against breast cancer (BRCA) remains unclear. In this study. we aim to investigate the bioactive compounds and mechanisms of SUANPANQI in the treatment of BRCA based on network pharmacology and molecular docking.MethodsThe compounds were collected from previous research. SwissADME was used to screen bioactive compounds. The targets corresponding to SUANPANQI and BRCA were obtained using MalaCards and SwissTargetPrediction. SUANPANQI-related and BRCA-related targets were found and then overlapped to get intersections, which represented potential anti-BRCA targets of SUANPANQI. The Cytoscape software was used to construct bioactive compounds targeting the BRCA network. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of the targets was extracted from the metascape database, then conducted using the Cluster Profiler package in R software. Protein-Protein interaction (PPI) network was constructed using the STRING online database and analyzed using Cytoscape software. Pivotal genes were screened using the topological analysis, survival analysis, and pathological stage analysis. Molecular docking analysis was used to verify whether the bioactive compounds had a definite affinity with the pivotal targets.ResultsSixty-five bioactive compounds of SUANPANQI were involved with 225 predicted BRCA targets. Then, a compound-target network and a PPI network were constructed. The GO analysis and KEGG enrichment analysis suggested that SUANPANQI worked against BRCA via PI3K-Akt, Ras, FoxO, Rap1, and ErbB signaling pathways, etc. After topological analysis, survival analysis, and pathological stage analysis of the SUANPANQI potential targets against BRCA, 6 pivotal target genes (AR, HSP90AA1, MMP9, PGR, PTGS2, TNF) that were highly responsible for the therapeutic effects of SUANPANQI against BRCA were obtained. Molecular docking results showed that 6 bioactive compounds of SUANPANQI had strong binding efficiency with the 6 pivotal genes.ConclusionsThe present study clarifies the mechanism of SUANPANQI against BRCA through multiple targets and pathways, and provides evidence to support its clinical use.     

Application of organometallic chemistry in the formulation of a modern therapeutic drug by Ag nanoparticles green-mediated by Allium to treat the breast cancer

In the recent study, we decided to survey the capacities of metallic nanoparticles formulated by Allium monanthum (AgNPs) as a novel chemotherapeutic drug in the treatment of several types of breast cancers. Characterization of AgNPs was done by UV–Visible Spectroscopy (UV–Vis), Fourier Transformed Infrared Spectroscopy (FT‐IR), Transmission Electron Microscopy (TEM), and Field Emission Scanning Electron Microscopy (FE‐SEM). For investigating the antioxidant properties of AgNO₃, Allium monanthum, and AgNPs, the DPPH test was used in the presence of butylated hydroxytoluene as the positive control. To survey the cytotoxicity and anti-breast cancer effects of AgNO₃, Allium monanthum, and AgNPs, MTT assay was used on the breast adenocarcinoma (MCF7), breast carcinoma (Hs 578Bst), infiltrating ductal cell carcinoma (Hs 319.T), infiltrating lobular carcinoma of breast (UACC-3133), inflammatory carcinoma of the breast (UACC-732), and metastatic carcinoma (MDA-MB-453) cell lines. DPPH test revealed similar antioxidant potentials for Allium monanthum, AgNPs, and butylated hydroxytoluene. Silver nanoparticles had very low cell viability and anti-breast cancer properties dose-dependently against MCF7, Hs 578Bst, Hs 319.T, UACC-3133, UACC-732, and MDA-MB-453 cell lines without any cytotoxicity on the normal cell line. The best result of anti-breast cancer properties of AgNPs against the above cell lines was seen in the case of the UACC-3133 cell line. According to the above findings, the silver nanoparticles containing Allium monanthum aqueous extract can be administrated in humans for the treatment of several types of breast cancer especially breast adenocarcinoma, breast carcinoma, infiltrating ductal cell carcinoma, infiltrating lobular carcinoma of breast, inflammatory carcinoma of the breast, and metastatic carcinoma.     

Adenovirus adenine nucleotide translocator-2 shRNA effectively induces apoptosis and enhances chemosensitivity by the down-regulation of ABCG2 in breast cancer stem-like cells

Cancer stem cells (CSCs) are resistant to chemo- and radio-therapy, and can survive to regenerate new tumors. This is an important reason why various anti- cancer therapies often fail to completely control tumors, although they kill and eliminate the bulk of cancer cells. In this study, we determined whether or not adenine nucleotide translocator-2 (ANT2) suppression could also be effective in inducing cell death of breast cancer stem-like cells. A sub-population (SP; CD44+/ CD24-) of breast cancer cells has been reported to have stem/progenitor cell properties. We utilized the adeno- ANT2 shRNA virus to inhibit ANT2 expression and then observed the treatment effect in a SP of breast cancer cell line. In this study, MCF7, MDA-MB-231 cells, and breast epithelial cells (MCF10A) mesenchymally-transdifferentiated through E-cadherin knockdown were used. ANT2 expression was high in both stem-like cells and non-stem-like cells of MCF7 and MDA-MB-231 cells, and was induced and up-regulated by mesenchymal transdifferentiation in MCF10A cells (MCF10A(EMT)). Knockdown of ANT2 by adeno-shRNA virus efficiently induced apoptotic cell death in the stem-like cells of MCF7 and MDA-MB-231 cells, and MCF10A(EMT). Stem-like cells of MCF7 and MDA-MB-231, and MCF10A(EMT) cells exhibited increased drug (doxorubicin) resistance, and expressed a multi-drug resistant related molecule, ABCG2, at a high level. Adeno-ANT2 shRNA virus markedly sensitized the stem-like cells of MCF7 and MDA-MB-231, and the MCF10A(EMT) cells to doxorubicin, which was accompanied by down-regulation of ABCG2. Our results suggest that ANT2 suppression by adeno-shRNA virus is an effective strategy to induce cell death and increase the chemosensitivity of stem-like cells in breast cancer.     

Antiproliferative effect of 2-Hydroxy-6-tridecylbenzoic acid from ginkgo biloba sarcotestas through the aryl hydrocarbon receptor pathway in triple-negative breast cancer cells

Abstract

This study aims to isolate the potential antiproliferative and cytotoxic compounds from ginkgo biloba sarcotestas (GBS) and investigates the underlying mechanism in human MDA-MB-231 and mouse 4T-1 triple-negative breast cancer cells. Our results showed that 2-Hydroxy-6-tridecylbenzoic acid was isolated by cytotoxicity-guided fractionation where different fractions were assessed using MTT assay against MDA-MB-231 and 4T-1 cells. Colony formation assay showed that 2-Hydroxy-6-tridecylbenzoic acid significantly inhibited cell proliferation. The inhibition was associated with the enhancement of cytochrome P450 (CYP) 1B1 expression in a dose- and time-dependent manner and no significant change of CYP1A1 expression by qPCR and Western blot assays in MDA-MB-231 and 4T-1 cells. The mechanism was further demonstrated by the activation of aryl hydrocarbon receptor (AhR) pathway with the upregulation of AhR, AhR nuclear translocator (ARNT) and AhR-dependent xenobiotic response elements (XRE) activity. These findings may have implications for development of anticancer agents containing 2-Hydroxy-6-tridecylbenzoic acid as functional additives.     

Exploring the anticancer effects of tin oxide nanoparticles synthesized by pulsed laser ablation technique against breast cancer cell line through downregulation of PI3K/AKT/mTOR signaling pathway

Tin oxide nanoparticles (SnO₂ NPs) demonstrate potential anti-cancer functions. However, the anti-cancer mechanisms of SnO₂ NPs have not been explored in detail. In the present study, we synthesized SnO₂ NPs through laser ablation technique and examined their anticancer mechanisms and the probable involvement of the PI3K/AKT mediated pathways in human breast cancer cells (MCF-7) in vitro. The synthesized SnO₂ NPs were characterized by transmission electron microcopy (TEM), dynamic light scattering (DLS), and Fourier-transform infrared spectroscopy (FTIR) techniques. Afterwards, the breast cancer cells were incubated with increasing concentrations of SnO₂ NPs, and inhibition of cell proliferation was assessed by the viability assay. Furthermore, the quantification of reactive oxygen species (ROS) and apoptosis were examined by flow cytometry followed by superoxide dismutase (SOD) and catalase (CAT) activity as well as mitochondrial membrane potential assays. The expression levels of phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), mechanistic target of rapamycin (mTOR), B-cell lymphoma 2 (Bcl-2), and Bax were also assessed by western blot and quantitative real time PCR (qRT-PCR). It was shown that SnO₂ NPs, 30 nm, with potential colloidal stability selectively prevented the proliferation of MCF-7 in comparison with MCF-10A cells and triggered ROS production, apoptosis, deactivation of SOD and CAT activity, and mitigation of mitochondrial membrane potential. Moreover, SnO₂ NPs stimulated mitochondrial-mediated apoptosis pathway by overexpression of Bax/Bcl-2 and downregulation of p-PI3K/p-AKT/p-mTOR signaling pathway. This data elucidates the possible mechanisms by which SnO₂ NPs may stimulate their anticancer effects.     

6‐Propyl‐2‐thiouracil versus 6‐methoxymethyl‐2‐thiouracil: enhancing the hydrogen‐bonded synthon motif by replacement of a methylene group with an O atom

The understanding of intermolecular interactions is a key objective of crystal engineering in order to exploit the derived knowledge for the rational design of new molecular solids with tailored physical and chemical properties. The tools and theories of crystal engineering are indispensable for the rational design of (pharmaceutical) cocrystals. The results of cocrystallization experiments of the antithyroid drug 6‐propyl‐2‐thiouracil (PTU) with 2,4‐diaminopyrimidine (DAPY), and of 6‐methoxymethyl‐2‐thiouracil (MOMTU) with DAPY and 2,4,6‐triaminopyrimidine (TAPY), respectively, are reported. PTU and MOMTU show a high structural similarity and differ only in the replacement of a methylene group (–CH₂–) with an O atom in the side chain, thus introducing an additional hydrogen‐bond acceptor in MOMTU. Both molecules contain an ADA hydrogen‐bonding site (A = acceptor and D = donor), while the coformers DAPY and TAPY both show complementary DAD sites and therefore should be capable of forming a mixed ADA/DAD synthon with each other, i.e. N—H…O, N—H…N and N—H…S hydrogen bonds. The experiments yielded one solvated cocrystal salt of PTU with DAPY, four different solvates of MOMTU, one ionic cocrystal of MOMTU with DAPY and one cocrystal salt of MOMTU with TAPY, namely 2,4‐diaminopyrimidinium 6‐propyl‐2‐thiouracilate–2,4‐diaminopyrimidine–N,N‐dimethylacetamide–water (1/1/1/1) (the systematic name for 6‐propyl‐2‐thiouracilate is 6‐oxo‐4‐propyl‐2‐sulfanylidene‐1,2,3,6‐tetrahydropyrimidin‐1‐ide), C₄H₇N₄⁺·C₇H₉N₂OS⁻·C₄H₆N₄·C₄H₉NO·H₂O, (I), 6‐methoxymethyl‐2‐thiouracil–N,N‐dimethylformamide (1/1), C₆H₈N₂O₂S·C₃H₇NO, (II), 6‐methoxymethyl‐2‐thiouracil–N,N‐dimethylacetamide (1/1), C₆H₈N₂O₂S·C₄H₉NO, (III), 6‐methoxymethyl‐2‐thiouracil–dimethyl sulfoxide (1/1), C₆H₈N₂O₂S·C₂H₆OS, (IV), 6‐methoxymethyl‐2‐thiouracil–1‐methylpyrrolidin‐2‐one (1/1), C₆H₈N₂O₂S·C₅H₉NO, (V), 2,4‐diaminopyrimidinium 6‐methoxymethyl‐2‐thiouracilate (the systematic name for 6‐methoxymethyl‐2‐thiouracilate is 4‐methoxymethyl‐6‐oxo‐2‐sulfanylidene‐1,2,3,6‐tetrahydropyrimidin‐1‐ide), C₄H₇N₄⁺·C₆H₇N₂O₂S⁻, (VI), and 2,4,6‐triaminopyrimidinium 6‐methoxymethyl‐2‐thiouracilate–6‐methoxymethyl‐2‐thiouracil (1/1), C₄H₈N₅⁺·C₆H₇N₂O₂S⁻·C₆H₈N₂O₂S, (VII). Whereas in (I) only an AA/DD hydrogen‐bonding interaction was formed, the structures of (VI) and (VII) both display the desired ADA/DAD synthon. Conformational studies on the side chains of PTU and MOMTU also revealed a significant deviation for cocrystals (VI) and (VII), leading to the desired enhancement of the hydrogen‐bond pattern within the crystal.