Ni(II), Cu(II), and Zn(II) Diethyldithiocarbamate Complexes Show Various Activities Against the Proteasome in Breast Cancer Cells

A series of three complexes with diethyldithiocarbamate ligand and three different metals (Ni, Cu, Zn) was prepared, confirmed by X-ray crystallography, and tested in human breast cancer MDA-MB-231 cells. Zinc and copper complexes, but not nickel complex, were found to be more active against cellular 26S proteasome than against purified 20S proteasome core particle. One of the possible explanations is inhibition of JAMM domain in the 19S proteasome lid

Synthesis, Characterization, and Reactivity of the Stable Iron Carbonyl Complex [Fe(CO)(N4Py)](ClO₄)₂: Photoactivated Carbon Monoxide Release, Growth Inhibitory Activity, and Peptide Ligation

Photoactivated carbon monoxide (CO) release by the iron carbonyl complex [FeII(CO)(N4Py)](ClO4)2 (1) is described. Compound 1 is a low-spin ferrous complex that is highly stable and soluble in aerobic aqueous solutions. CO release was studied by the substitution of MeCN for CO, which displays saturation kinetics, and by the transfer of CO to deoxymyoglobin, which is slow in the dark but fast upon irradiation with UV light (365 nm). Compound 1 is active against PC-3 prostate cancer cells and shows potent photoinduced cytotoxicity. In addition, the iron carbonyl complex was attached to a short peptide toward the goal of tissue or cell-specific delivery

Synthesis, Characterization, and Reactivity of the Stable Iron Carbonyl Complex [Fe(CO)(N4Py)](ClO₄)₂: Photoactivated Carbon Monoxide Release, Growth Inhibitory Activity, and Peptide Ligation

Photoactivated carbon monoxide (CO) release by the iron carbonyl complex [FeII(CO)(N4Py)](ClO4)2 (1) is described. Compound 1 is a low-spin ferrous complex that is highly stable and soluble in aerobic aqueous solutions. CO release was studied by the substitution of MeCN for CO, which displays saturation kinetics, and by the transfer of CO to deoxymyoglobin, which is slow in the dark but fast upon irradiation with UV light (365 nm). Compound 1 is active against PC-3 prostate cancer cells and shows potent photoinduced cytotoxicity. In addition, the iron carbonyl complex was attached to a short peptide toward the goal of tissue or cell-specific delivery

Western blot <i>in vivo</i> analysis.

<p>Female nude mice bearing MDA-MB-231 tumors were treated with either vehicle (control) or the compounds AuD6 and AuD8 at 1 mg kg⁻¹ d⁻¹. Tumors were collected and the corresponding tissues prepared for Western blot analysis after either 13-day treatment (<b>A</b>) or 27-day treatment (<b>B</b>) [I and II denote distinct experiments]. Tissues were also prepared for the assays of caspase-3 activity (<b>C</b>) and of proteasomal CT-like activity (<b>D</b>) after 27 days of treatment.</p

Annexin–V FITC/PI assay.

<p>MDA-MB-231 cells were treated with the complexes AuD6 and AuD8 (20 µM) for 16 and 24 h. Then, cells were labeled with Annexin–V FITC and PI and analyzed by flow cytometry in order to evaluate the percentage of apoptotic cells. Apoptotic cells at early stage occur in the lower right quadrant while apoptotic cells at late stage set in the up-right part. The percentage in the lower left quadrant is due to viable cells whereas the upper left part to non-apoptotic cell death.</p

Schematic diagram showing the various mechanisms associated with inhibition of tumor growth and induction of apoptosis by B-DIM.

<p>Schematic diagram showing the various mechanisms associated with inhibition of tumor growth and induction of apoptosis by B-DIM.</p

Western blot and morphological analysis (concentration-dependent study).

<p><b>A</b>, Western blot analysis of breast cancer MDA-MB-231 cell extracts. Cells were treated with the complexes AuD6 and AuD8 at the indicated concentrations for 24 h. <b>B</b>, Western blot analysis of the p27 protein amount in MDA-MB-231 cell extract after treatment with the compound AuD8 at the indicated concentrations for 24 h. The solvent DMSO was used as a control while GAPDH as a loading control. <b>C</b>, Apoptotic morphological changes of MDA-MB-231 cells after treatment with AuD6 and AuD8 at the indicated concentrations for 24 h (phase contrast imaging, 100× magnification).</p

<i>In vitro</i> inhibition of proteasome.

<p>IC₅₀ values (µM±SD) obtained for the three proteasomal activities on the purified 20S proteasome and on MDA-MB-231 cell extract after 2 h incubation.</p

Chemical structures of investigated gold(III)-based compounds AuD6 (A) and AuD8 (B).

<p>Chemical structures of investigated gold(III)-based compounds AuD6 (A) and AuD8 (B).</p

Antitumor activity <i>in vivo</i> on MDA-MB-231 xenografts.

<p>Female nude mice bearing MDA-MB-231 tumors were treated with either vehicle (control) or the compounds AuD6 and AuD8 at 1 mg kg⁻¹ d⁻¹. <b>A,</b> Inhibition of xenograft growth by both complexes. Tumor volumes were measured every other day using a caliper. Points represent the mean ± SD (bars) of seven mice per group. The insert depicts representative tumors from each treatment group; * = p<0.05. <b>B</b>, If only the most responsive mice are considered, the xenograft growth inhibition is greater. The insert shows average weights of mice over time; ** = p<0.01. <b>C</b>, Immunohistochemical p27 and TUNEL staining of tumor samples indicates proteasome inhibition and apoptosis as a result of both compounds. Stronger p27 staining is observed following AuD8 treatment, and more TUNEL positive cells are observed following AuD6 treatment. Brown colored cells are considered positive.</p