Synthesis, structural characterization and antitumor activity of six rare earth metal complexes with 8-hydroxyquinoline derivatives.

The rare earth metal Gd(III), Yb(III), Lu(III), Eu(III), Tb(III) and Ho(III) complexes 1-6 with 2-((2-(pyridin-2-yl)hydrazono)methyl)quinolin-8-ol (H-L) as ligands were synthesized. The in vitro cytotoxicity assay indicated that the cytotoxicity of 1 was equivalent to cisplatin and higher than that of H-L and other complexes towards T24 tumor cells. The mechanism study indicated that 1 caused significant up-regulation of the proteins p27, p21 and p53 in T24 cells and cell cycle arrest in G2 phase. In addition, 1 induced effective T24 cells apoptosis via mitochondrial dysfunction pathway, which was indicated by changes in mitochondrial membrane potential (Δψ), reactive oxygen species (ROS), intracellular Ca2+ and the mitochondria-related proteins (including cytochrome C (Cyt C), B-cell lymphoma-2 (Bcl-2), Bcl-2-associated x (Bax) and apoptotic protease activating factor-1 (Apaf-1)). Moreover, 1 could activate caspase-3/8/9 in T24 cells. Therefore, complex 1 is a promising and potent anticancer drug candidate.

Synthesis and in vitro antitumor activity evaluation of copper(II) complexes with 5-pyridin-2-yl-[1,3]dioxolo[4,5-g]isoquinoline derivatives.

Seven Cu(II) complexes with 5-pyridin-2-yl-[1,3]dioxolo[4,5-g]isoquinoline derivatives as ligands: [Cu2(L1)2Cl4] (1), [Cu(L2)Cl2] (2), [Cu(L1)(NO3)2] (3), [Cu(L2)(NO3)2] (4), [Cu(L3)Cl2] (5), [Cu(L3)Br2] (6) and [Cu(L3)(NO3)2] (7){L1=9-nitro-5-pyridin-2-yl-[1,3]dioxolo[4,5-g]isoquinoline, L2=4-nitro-5-pyridin-2-yl-[1,3]dioxolo[4,5-g]isoquinoline, L3=9-bromo-5-pyridin-2-yl-[1,3]dioxolo[4,5-g]isoquinoline}, were synthesized and characterized. Their in vitro anticancer activities against T-24, MGC-80-3, HeLa, Hep-G2, A549 and SK-OV-3 were evaluated. Compared with their corresponding ligands, most of these complexes exhibited enhanced anticancer activities in contrast to their corresponding ligands and copper salt. Among them, complexes 1 and 3 displayed selective cytotoxicity to HeLa cells comparing with normal liver cell HL-7702, with IC50 values of 5.03 ±â€¯1.20 µM and 10.05 ±â€¯0.52 µM, respectively. Complexes 1 and 3 inhibited telomerase activity by interacting with c-myc promoter elements, and therefore exerted their antitumor activity. Furthermore, complexes 1 and 3 could trigger cell apoptosis via disruption of mitochondrial pathway through notably increased reactive oxygen species (ROS) levels, loss of mitochondrial membrane potential (Δψm), increase of the cytochrome c and apaf-1, decrease of bcl-2, and activation of caspases 3/9. Complexes 1 and 3 exhibited enhanced cytotoxicity, presenting synergetic effect after the ligands coordinated to copper(II) center.

Alteration of Androgen Receptor Protein Stability by Triptolide in LNCaP Cells.

Background and Objective: Although triptolide was effective for prostate cancer (PCa), the mechanism is still unclear. Androgen receptor (AR) plays a large role in the development and progression of PCa, even after castration. The present study aimed at investigating the effects of triptolide on AR protein stability and the possible mechanism. Materials and Methods: By blocking protein synthesis with cycloheximide (CHX), the effect of triptolide on AR protein stability was investigated with western blot assay. The potential role of calpains in triptolide reduced AR protein stability was investigated with calpain inhibitor and Ca2+ chelator. Results: Triptolide down-regulated AR protein level when protein synthesis was blocked by CHX, demonstrating the decrease of AR protein stability. The AR protein level was restored when the cells were co-treated with triptolide and calpain inhibitor or Ca2+ chelator, indicating the important role of calpains. Conclusions: The results indicate that triptolide can activate calpain via promoting intracellular Ca2+ accumulation, and thus decrease the stability of AR protein, subsequently resulting in the breakdown of the AR protein in LNCaP cells. This work provides an experimental basis and evidence to elucidate the anti-PCa mechanisms of triptolide.

Syntheses, Crystal Structures, and Antitumor Activities of Copper(II) and Nickel(II) Complexes with 2-((2-(Pyridin-2-yl)hydrazono)methyl)quinolin-8-ol.

Two transition metal complexes with 2-((2-(pyridin-2-yl)hydrazono)methyl)quinolin-8-ol (L), [Cu(L)Cl2]2 (1) and [Ni(L)Cl2]·CH2Cl2 (2), were synthesized and fully characterized. Complex 1 exhibited high in vitro antitumor activity against SK-OV-3, MGC80-3 and HeLa cells with IC50 values of 3.69 ± 0.16, 2.60 ± 0.17, and 3.62 ± 0.12 µM, respectively. In addition, complex 1 caused cell arrest in the S phase, which led to the down-regulation of Cdc25 A, Cyclin B, Cyclin A, and CDK2, and the up-regulation of p27, p21, and p53 proteins in MGC80-3 cells. Complex 1 induced MGC80-3 cell apoptosis via a mitochondrial dysfunction pathway, as shown by the significantly decreased level of bcl-2 protein and the loss of Δψ, as well as increased levels of reactive oxygen species (ROS), intracellular Ca2+, cytochrome C, apaf-1, caspase-3, and caspase-9 proteins in MGC80-3 cells.

Synthesis, crystal structure, cytotoxicity and action mechanism of a Rh(iii) complex with 8-hydroxy-2-methylquinoline as a ligand.

A rhodium(iii) complex, [Rh(MQ)(DMSO)2Cl2] (1), with 8-hydroxy-2-methylquinoline as the ligand was synthesized and characterized. Complex 1 exhibited cytotoxicity against BEL-7404, Hep-G2, NCI-H460, T-24, and A549 cell lines with IC50 values in the micromolar range (6.52-17.86 µM). Various experiments on the Hep-G2 cells showed that complex 1 caused cell cycle arrest at the S phase, downregulation of cdc25 A, cyclin A, cyclin B and CDK2, and upregulation of p21, p27 and p53. Furthermore, cytotoxicity mechanism studies suggested that complex 1-induced apoptosis was achieved via disruption of the mitochondrial function, which led to a significant loss of the mitochondrial membrane potential, an increase in the cellular levels of reactive oxygen species, cytochrome c, and apaf-1, and a fluctuation of the intracellular Ca2+ concentration. Taken altogether, complex 1 can trigger cancer cell death by inducing apoptosis through a mitochondrial dysfunction pathway.

Synthesis and antitumor mechanism of a new iron(iii) complex with 5,7-dichloro-2-methyl-8-quinolinol as ligands.

A new iron(iii) complex with 5,7-dichloro-2-methyl-8-quinolinol (HClMQ) as ligands, i.e., [Fe(ClMQ)2Cl] (1), was synthesized and evaluated for its anticancer activity. Compared to the HClMQ ligand, complex 1 showed a higher cytotoxicity towards a series of tumor cell lines, including Hep-G2, BEL-7404, NCI-H460, A549, and T-24, with IC50 values in the range of 5.04-14.35 µM. Notably, the Hep-G2 cell line was the most sensitive to complex 1. Mechanistic studies indicated that complex 1 is a telomerase inhibitor targeting c-myc G-quadruplex DNA and can trigger cell apoptosis via inducing cell cycle arrest and DNA damage.