Effects of γ-radiation on cell growth, cell cycle and promoter methylation of 22 cell cycle genes in the 1321NI astrocytoma cell line

Ruthenium (II) complex cis-[RuII(ŋ2-O2CC7H7O2)(dppm)2]PF6-hmxbato induces ROS-mediated apoptosis in lung tumor cells producing selective cytotoxicity

Ruthenium complexes have been extensively explored as potential molecules for cancer treatment. Considering our previous findings on the remarkable cytotoxic activity exhibited by the ruthenium (II) complex 3-hydroxy-4-methoxybenzoate (hmxbato)-cis-[RuII(ŋ2-O2CC7H7O2)(dppm)2]PF6 against Leishmania promastigotes and also the similar metabolic characteristics between trypanosomatids and tumor cells, the present study aimed to analyze the anticancer potential of hmxbato against lung tumor cells, as well as the partial death mechanisms involved. Hmxbato demonstrated selective cytotoxicity against A549 lung tumor cells. In addition, this complex at a concentration of 3.8 µM was able to expressively increase the generation of reactive oxygen species (ROS) in tumor cells, causing an oxidative stress that may culminate in: (1) reduction in cellular proliferation; (2) changes in cell morphology and organization patterns of the actin cytoskeleton; (3) cell arrest in the G2/M phase of the cell cycle; (4) apoptosis; (5) changes in the mitochondrial membrane potential and (6) initial DNA damage. Furthermore, we demonstrated that the induction of programmed cell death can occur by the intrinsic apoptotic pathway through the activation of caspases. It is also worth highlighting that hmxbato exhibited predominant actions on A549 tumor cells in comparison to BEAS-2B normal bronchial epithelium cells, which makes this complex an interesting candidate for the design of new drugs against lung cancer.

Combination of RERG and ZNF671 methylation rates in circulating cell-free DNA: A novel biomarker for screening of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a prevalent malignancy in Southeast Asia, hence, identifying easily detectable biomarkers for NPC screening is essential for better diagnosis and prognosis. Using genome-wide and targeted analyses based on next-generation sequencing approaches, we previously showed that gene promoters are hypermethylated in NPC tissues. To confirm whether DNA methylation rates of genes could be used as biomarkers for NPC screening, 79 histologically diagnosed NPC patients and 29 noncancer patients were recruited. A convenient quantitative analysis of DNA methylation using real-time PCR (qAMP) was carried out, involving pretreatment of tissue DNA, and circulating cell-free DNA (ccfDNA) from nonhemolytic plasma, with methylation-sensitive and/or methylation-dependent restriction enzymes. The qAMP analyses revealed that methylation rates of RERG, ZNF671, ITGA4, and SHISA3 were significantly higher in NPC primary tumor tissues compared to noncancerous tissues, with sufficient diagnostic accuracy of the area under receiver operating characteristic curves (AUC). Interestingly, higher methylation rates of RERG in ccfDNA were statistically significant and yielded a very good AUC; however, those of ZNF671, ITGA4, and SHISA3 were not significant. Furthermore, the combination of methylation rates of RERG and ZNF671 in ccfDNA showed higher diagnostic accuracy than either of them individually. In conclusion, the methylation rates of specific genes in ccfDNA can serve as novel biomarkers for early detection and screening of NPC.

Development of four ruthenium polypyridyl complexes as antitumor agents: Design, biological evaluation and mechanism investigation

Ruthenium complexes are expected to be new opportunities for the development of antitumor agents. Herein, four ruthenium polypyridyl complexes ([Ru(bpy)₂(CAPIP)](ClO₄)₂ (Ru(II)-1, bpy = 2,2'-bipyridine; CAPIP = (E)-2-(2-(furan-2-yl)vinyl)-1H-imidazo[4,5-f][1,10]phenanthroline), [Ru(phen)₂(CA-PIP)](ClO₄)₂ (Ru(II)-2, phen = 1,10-phenanthroline), [Ru(dmb)₂(CAPIP)](ClO₄)₂ (Ru(II)-3, dmb = 4,4'-dimethyl-2,2'-bipyridine), [Ru(dmb)₂(ETPIP)](ClO₄)₂ (Ru(II)-4, ETPIP = 2-(4-(thiophen-2-ylethynyl)phenyl)-1H-imidazo[4,5-f][1,10]phen-anthroline)) have been investigated as mitochondria-targeted antitumor metallodrugs. DNA binding studies indicated that target Ru(II) complexes interacts with CT DNA (calf thymus DNA) by an intercalative mode. Cytotoxicity assay results demonstrate that Ru(II) complexes show high cytotoxicity against A549 cells with low IC₅₀ value of 23.6 ± 2.3, 20.1 ± 1.9, 22.7 ± 1.8 and 18.4 ± 2.3 μM, respectively. Flow cytometry and morphological analysis revealed that these Ru(II) complexes can induce apoptosis in A549 cells. Intracellular reactive oxygen species (ROS) and mitochondrial membrane potential were also investigated by ImageXpress Micro XLS system. The experimental results indicate that the reactive oxygen species in A549 cells increased significantly and mitochondrial membrane potential decreased obviously. In addition, colocalization studies shown these complexes could get to the cytoplasm through the cell membrane and accumulate in the mitochondria. Furthermore, Ru(II) complexes can effectively induces cell cycle arrest at the S phase in A549 cells. Finally, cell invasion assay and quantitative studies were also performed to investigate the mechanism of this process. All in together, this study suggested that these Ru(II) complexes could induce apoptosis in A549 cells through cell cycle arrest and ROS-mediated mitochondrial dysfunction pathway.

Design and synthesis of new ruthenium polypyridyl complexes with potent antitumor activity in vitro

We herein report the synthesis, characterization and anticancer activity of BTPIP (2-(4-(benzo[b]thiophen-2-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline) and its four ruthenium(II) polypyridyl complexes [Ru(NN)₂(BTPIP)](ClO₄)₂ (N-N = bpy = 2,2'-bipyridine, Ru(II)-1; phen = 1,10-phenanthroline, Ru(II)-2; dmb = 4,4'-dimethyl-2,2'-bipyridine, Ru(II)-3; dmp = 2,9-dimethyl-1,10-phenanthroline, Ru(II)-4). The DNA binding behaviors reveal that the complexes bind to calf thymus DNA by intercalation. Cytotoxicity of the complexes against A549, HepG-2, SGC-7901 and Hela cells were evaluated in vitro. Complexes Ru(II)-1, Ru(II)-2, Ru(II)-3, Ru(II)-4 show moderate activity on the cell proliferation in A549 cells with IC₅₀ values of 9.3 ± 1.2, 12.1 ± 1.6, 10.3 ± 1.6, 8.9 ± 1.2 μM, respectively. Apoptosis assessment, intracellular mitochondrial membrane potential (MMP), location in mitochondria, reactive oxygen species (ROS), cell invasion assay and cell cycle arrest were also performed to explore the mechanism of this action. When the concentration of the ruthenium(II) complexes is increased, the amount of reactive oxygen species increases obviously and the mitochondrial membrane potential decreases dramatically in A549 cells. Most importantly, the ruthenium(II) polypyridyl complexes could arrive the cytoplasm through the cell membrane and accumulate in the mitochondria. These results showed that the ruthenium(II) complexes could induce apoptosis in A549 cells through an ROS-mediated mitochondrial dysfunction pathway.

Study of the Potential Radiomitigator Effect of Quercetin on Human Lymphocytes

Several substances of synthetic and natural origin have been studied to determine their ability to protect the body from damage caused by ionizing radiation. Among these substances, quercetin has been shown to be a naturally occurring molecule with high radioprotective and radiomitigator potential due to its antioxidant properties. The objective of this work was to ascertain the potential radiomitigator effect of quercetin on chromosome aberration yield in lymphocytes of in vitro-irradiated human peripheral blood. At first, the DPPH (2,2-diphenyl-1-picryl-hydrazyl) radical capture test was performed to determine the antioxidant activity of quercetin and to select the concentrations to be tested. The blood was irradiated at doses of 2.5, 3.5, and 4.5 Gy and lymphocytes were cultured with quercetin at preselected concentrations of 37.5 and 75 μM. Then, the slides were prepared for scoring unstable chromosome aberrations (dicentrics, rings, and fragments). The results showed that the lymphocytes irradiated and later exposed to quercetin presented a lower frequency of chromosomal alterations compared to the control sample which was irradiated and not exposed to quercetin. The results suggest a potential radiomitigator effect of the flavonoid quercetin on human lymphocytes exposed, in vitro, to ionizing radiation. This effect may be related to decrease in the release of cytokines (INF-γ, PGE2, IL-1β, IL6, IL-8) involved in the proinflammatory processes as well as downregulation of NF-kB and reduction of expression TGF-β.