New chimeric HDAC inhibitors for the treatment of colorectal cancer

Colorectal cancer is the third most common cause of cancer-associated deaths due to a high recurrence rate and an increasing occurrence of resistance to established therapies. This highlights the importance of developing new chemotherapeutic agents. The current study focuses on cancer-specific targets such as apoptosis-inhibiting survivin, which distinguishes cancer cells from healthy tissue. A combination of pharmacophores of established anticancer agents to afford chimeric pleiotropic chemotherapeutic agents was tested on this cancer entity. We analysed the effects of the dual mode anticancer agents, animthioxam, brimbam, troxbam, and troxham, as well as their structural congeners suberoylanilide hydroxamic acid and combretastatin A-4 on human cancer cell lines. Their cytotoxicity was determined using the MTT assay, further techniques for detecting apoptotic events, cell cycle analyses, clonogenic and wound healing assays, immunostaining, histone deacetylase (HDAC) activity measurements, and Western blot analysis for the detection of survivin expression in HCT116 colon cancer cells. Molecular docking studies were conducted to assess potential molecular targets of the test compounds. The test compounds were found selectively cytotoxic toward cancer cells by inducing apoptosis. The metastatic potential was effectively reduced by disruption of the microtubular cytoskeleton. The test compounds were also proven to be general HDAC inhibitors and to lead to reduced survivin expression.

Trans-[bis(benzimidazol-2-ylidene)dichlorido]platinum(II) complexes with peculiar modes of action and activity against cisplatin-resistant cancer cells

Three series of cis- and trans-[bis(benzimidazol-2-ylidene)dichlorido]platinum(II) and cis-[(benzimidazol-2-ylidene)(DMSO)dichlorido]platinum(II) complexes were synthesised and screened for cytotoxicity against six human cancer cell lines. Depending on their N-alkyl and 5-alkoxycarbonyl substituents, two-digit nanomolar to single-digit micromolar IC₅₀ values against cancer cell lines intrinsically resistant to or ill-responding to cisplatin were reached by both cis- and trans-configured complexes. The stability of the complexes under aqueous biotest conditions was shown via ¹H and ¹⁹⁵Pt NMR monitoring to be dependent on their configuration and their N-substituents. Localisation studies employing click reactions with 1-alkyne- or cyclopropene-tagged derivatives revealed that the cis-complexes accumulated in the cell nuclei and the trans-complexes in the mitochondria. While the most active cis-complexes showed modes of action akin to those of cisplatin, the most active trans-complexes differed from cisplatin by much lower rates of cellular uptake and ROS production, and by their non-interaction with the cell cycle and the DNA of cancer cells. Thus, we identified structural key elements for the synthesis of optimised trans-configured NHC platinum(II) complexes with high activity also against cisplatin-refractory cancer cells.

Ruthenium(II)-Tris-pyrazolylmethane Complexes Inhibit Cancer Cell Growth by Disrupting Mitochondrial Calcium Homeostasis

While ruthenium arene complexes have been widely investigated for their medicinal potential, studies on homologous compounds containing a tridentate tris(1-pyrazolyl)methane ligand are almost absent in the literature. Ruthenium(II) complex 1 was obtained by a modified reported procedure; then, the reactions with a series of organic molecules (L) in boiling alcohol afforded novel complexes 2–9 in 77–99% yields. Products 2–9 were fully structurally characterized. They are appreciably soluble in water, where they undergo partial chloride/water exchange. The antiproliferative activity was determined using a panel of human cancer cell lines and a noncancerous one, evidencing promising potency of 1, 7, and 8 and significant selectivity toward cancer cells. The tested compounds effectively accumulate in cancer cells, and mitochondria represent a significant target of biological action. Most notably, data provide convincing evidence that the mechanism of biological action is mediated by the inhibiting of mitochondrial calcium intake.

Distinct mechanism of action for antitumoral neutral cyclometalated Pt(II)-complexes bearing antifungal imidazolyl-based drugs

Three neutral Pt(II) complexes containing 1-Methylimidazole and the antifungal imidazolyl drugs Clotrimazole and Bifonazole have been prepared. The general formula of the new derivatives is [Pt(κ²-(C^N)Cl(L)], where C^N stands for ppy = 2-phenylpyridinate, and L = 1-Methylimidazole (MeIm) for [Pt-MeIm]; L = Clotrimazole (CTZ) for [Pt-CTZ] and L = Bifonazole (BFZ) for [Pt-BFZ]). The complexes have been completely characterized in solution and the crystal structures of [Pt-BFZ] and [Pt-CTZ] have been resolved. Complexes [Pt-MeIm] and [Pt-BFZ] present higher cytotoxicity than cisplatin in SW480 (colon adenocarcinoma), A549 (lung adenocarcinoma) and A2780 (ovarian cancer) cell lines. [Pt-MeIm] shows the highest accumulation in A549 cells, in agreement with its inability to interact with serum albumin. By contrast, [Pt-CTZ] and [Pt-BFZ] interact with serum proteins, a fact that reduces their bioavailability. The strongest interaction with bovine serum albumin (BSA) is found for [Pt-BFZ], which is the least internalized inside the cells. All the complexes are able to covalently interact with DNA. The most cytotoxic complexes, [Pt-MeIm] and [Pt-BFZ] induce cellular accumulation in G0/G1 and apoptosis by a similar pathway, probably involving a reactive oxygen species (ROS) generation mechanism. [Pt-BFZ] turns out to be the most efficient complex regarding ROS generation and causes mitochondrial membrane depolarization, whereas [Pt-MeIm] induces the opposite effect, hyperpolarization of the mitochondrial membrane. On the contrary, the least cytotoxic complex, [Pt-CTZ] cannot block the cell cycle or generate ROS and the mechanism by which it induces apoptosis could be a different one.

Synthesis and in vitro anticancer activities of selenium N-heterocyclic carbene compounds

Fourteen novel selenium N-heterocyclic carbene (Se-NHC) compounds derived from 4,5-diarylimidazole were designed, synthesized, and evaluated as antiproliferative agents. Most of them were more effective toward A2780 ovarian cancer cells than HepG2 hepatocellular carcinoma cells. Among them, the most active compound 2b was about fourfold more active than the positive control ebselen against A2780 cells. In addition, this compound displayed twofold higher cytotoxicity to A2780 cells than to IOSE80 normal ovarian epithelial cells. Further studies revealed that 2b could induce reactive oxygen species production, damage mitochondrial membrane potential, block the cells in the G0/G1 phase, and finally promote A2780 cell apoptosis.

Guided Antitumoural Drugs: (Imidazol-2-ylidene)(L)gold(I) Complexes Seeking Cellular Targets Controlled by the Nature of Ligand L

Three [1,3-diethyl-4-(p-methoxyphenyl)-5-(3,4,5-trimethoxyphenyl)imidazol-2-ylidene](L)gold(I) complexes, 4 a (L=Cl), 5 a (L=PPh3 ), and 6 a (L=same N-heterocyclic carbene (NHC)), and their fluorescent [4-(anthracen-9-yl)-1,3-diethyl-5-phenylimidazol-2-ylidene](L)gold(I) analogues, 4 b, 5 b, and 6 b, respectively, were studied for their localisation and effects in cancer cells. Despite their identical NHC ligands, the last three accumulated in different compartments of melanoma cells, namely, the nucleus (4 b), mitochondria (5 b), or lysosomes (6 b). Ligand L was also more decisive for the site of accumulation than the NHC ligand because the couples 4 a/4 b, 5 a/5 b, and 6 a/6 b, carrying different NHC ligands, afforded similar results in cytotoxicity tests, and tests on targets typically found at their sites of accumulation, such as DNA in nuclei, reactive oxygen species and thioredoxin reductase in mitochondria, and lysosomal membranes. Regardless of the site of accumulation, cancer cell apoptosis was eventually induced. The concept of guiding a bioactive complex fragment to a particular subcellular target by secondary ligand L could reduce unwanted side effects.

Luminescent terpyridine appended geminal bisazide and bistriazoles: multinuclear Pt(II) complexes and AIPE-based DNA detection with the naked eye

We report square planar Pt(ii) complexes as luminescent biosensors for DNA detection in solution. The sensing is attributed to the aggregation induced bright red photoluminescence (AIPE) of the complexes in the presence of DNA that can be seen with the naked eye using only a 360 nm light source. Terpyridine appended luminescent geminal bistriazoles (L1-L4, from geminal bisazide A through azide-alkyne 'click' cycloaddition) with versatile chelating sites were explored for metal coordination and reaction with Pt(dmso)2Cl2 yielding tetranuclear and dinuclear complexes of Pt(ii) with different N∩N ligand environments. Thermally stable gem-bisazide and bistriazoles are hardly reported in the literature and this is the first report of terpyridine appended geminal bisazide and bistriazoles.

High cytotoxic and apoptotic effects of platinum(ii) complexes bearing the 4-acridinol ligand

4-Acridinol platinum(ii) complex PtA induces SK-OV-3/DDP cell apoptosis that is mediated by the mitochondrial dysfunction pathway.