A novel ruthenium(II)-polypyridyl complex inhibits cell proliferation and induces cell apoptosis by impairing DNA damage repair

A comparative study of novel ruthenium(III) and iron(III) complexes containing uracil; docking and biological studies

Structural and biological studies were conducted on the novel complexes [Fe(U)2(H2O)2]Cl3 (FeU) and [Ru(U)2(H2O)2]Cl3 (RuU) (U = 5,6-Diamino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione) to develop an anticancer drug candidate. The two complexes have been synthesized and characterized. Based on our findings, these complexes have octahedral geometry. The DNA-binding study proved that both complexes coordinated with CT-DNA. The docking study confirmed the potency of both complexes in downregulating the topoisomerase I protein through their high binding affinity. Biological studies have established that both complexes can act as potent anticancer agents against three cancer cell lines. RuU or FeU complexes induce apoptosis in breast cancer cells by increasing caspase9 protein and inhibiting proliferating cell nuclear antigen (PCNA) activity. In addition, both complexes down-regulate topoisomerase I expression in breast cancer cells. Therefore, the RuU and FeU complexes' anticancer activities were mediated via both apoptosis induction and topoisomerase I down-regulation. In conclusion, both complexes have dual anticancer activity pathways that may be responsible for the selective cytotoxicity of the complexes. This makes them more suitable for the development of novel cancer treatment strategies.

Chiral ruthenium(II) complex Δ-[Ru(bpy)2(o-FMPIP)] (bpy = bipyridine, o-FMPIP = 2-(2'-trifluoromethyphenyl) imidazo[4,5-f][1,10]phenanthroline) as potential apoptosis inducer via DNA damage

Chiral ruthenium(II) complexes have long been considered as potential anticancer agents. Herein, in vivo inhibitory activity of a chiral ruthenium(II) complex coordinated by ligand 2-(2'-trifluoromethyphenyl) imidazo [4,5-f][1,10]phenanthroline, Δ-[Ru(bpy)₂(o-FMPIP)] (D0402) on Kunming(KM) mice bearing tumor (H22 hepatic cancer) has been evaluated, and the results showed that the tumor weight of mice treated with 0.22 mg/(kg·day) D0402 via i.v. administration for 7 days decreased about 31.79% compared to the control group, while the body weight, as well as the thymus, spleen, liver, lung, and kidney indices of mice treated with D0402 observed almost no loss compared to the control group. Furthermore, the mechanism studies on anti-angiogenic showed that D0402 could inhibit the formation of angiogenesis in the transgenic Tg(fli1a: EGFP) zebrafish. After treated with D0402, the sub-intestinal vessels(SIVs) of the zebrafish became disordered and chaotic, and was dosage dependent. Moreover, the TUNEL analysis and comet assays revealed that D0402 can induce apoptosis of HepG2 cell through DNA damage, and this was further demonstrated by immunofluorescence analysis with the number of γ-H2AX increased following the increasing amount of D0402. Besides, in vivo toxicity of D0402 has also been investigated on the development of zebrafish embryo, and the results showed that there were no death or development delay occurred for zebrafish embryo treated with D0402 up to concentration of 60 μM. All in together, this study suggested that D0402 can be developed as a potential inhibitor against liver cancer through co-junction of anti-angiogenesis and apoptosis-inducing via DNA damage in the near future.

Systemic siRNA Delivery with a Dual pH-Responsive and Tumor-targeted Nanovector for Inhibiting Tumor Growth and Spontaneous Metastasis in Orthotopic Murine Model of Breast Carcinoma

Phenylboronic acid (PBA)-mediated tumor targeting nanovector is an attractive strategy for enhancing siRNA delivery and treatment of metastatic cancers. However, its nonspecific binding with various biological membranes containing cis-diol moieties restricts its potential application by systematic administration. Herein, we constructed a novel pH-activated “sheddable” PEG-coated nanoparticle for effective treatment of primary tumors and metastases, which was based on the conjugation of catechol group modified poly(ethylene glycol) (PEG-Cat) and PBA-terminated polyethylenimine (PEI-PBA) via the borate ester formed between PBA and Cat. By virtue of the pH-dependent stability of borate ester in an aqueous medium, the PEG-shell could “shield” the PBA ligand in systemic circulation to reduce its “off-target effect”, while PEG was detached at tumor extracellular pH (~6.5) to expose intact PBA moiety. Simultaneously, the PBA ligand could bind with overexpressed sialic acid residues on cancer cells, giving rise to enhanced cellular internalization. In addition, the PBA moieties could also couple with each 3'-end ribose of double-stranded siRNA. siRNAs were used as both a payload and a pH-responsive intermolecular cross-linker, and thereby acquired sufficient stability during circulating in blood and a rapidly triggered release in response to acidic endosomal/lysosomal pH-stimuli. As a result, this dual pH-sensitive nanoparticle showed enhanced siRNA uptake, gene silencing efficacy and anti-metastatic effects in vitro. Furthermore, in vivo studies demonstrated that PBA-based nanoparticles effectively accumulated in tumor and inhibited tumor growth and metastasis in 4T1 orthotopic mammary tumor model after intravenous administration.

Cellular Retinoic Acid Binding Protein 2 Is Strikingly Downregulated in Human Esophageal Squamous Cell Carcinoma and Functions as a Tumor Suppressor

Esophageal squamous cell carcinoma (ESCC) is the predominant pathotype of esophageal carcinoma (EC) in China, especially in Henan province, with poor prognosis and limited 5-year survival rate. Cellular retinoic acid binding protein 2 (CRABP2) is a member of the retinoic acid (RA) and lipocalin/cytosolic fatty-acid binding protein family and plays a completely contrary role in tumorigenesis through the retinoid signaling pathway, depending on the nuclear RA receptors (RAR) and PPARbeta/delta receptors. Presently, the biological role of CRABP2 in the development of ESCC has never been reported. Here, we firstly evaluated the expression of CRABP2 at both mRNA and protein levels and showed that it was remarkably downregulated in clinical ESCC tissues and closely correlated with the occurrence position, pathology, TNM stage, size, infiltration depth and cell differentiation of the tumor. Additionally, the biological function assays demonstrated that CRABP2 acted as a tumor suppressor in esophageal squamous carcinogenesis by significantly inhibiting cell growth, inducing cell apoptosis and blocking cell metastasis both in vitro and in vivo. All in all, our finding simplicate that CRABP2 is possibly an efficient molecular marker for diagnosing and predicting the development of ESCC.

A novelly synthesized phenanthroline derivative is a promising DNA-damaging anticancer agent inhibiting G1/S checkpoint transition and inducing cell apoptosis in cancer cells

PURPOSE

The study mainly aimed to determine the biological function of a novelly synthesized phenanthroimidazole derivative, named L233, and to explore its potential mechanisms.

METHODS

Cell survival was examined using the MTT assays, and the DNA-damaging role of L233 was explored using the comet assay. Moreover, the western blotting assays and immunofluorescence assays were used to detect DNA damage biomarkers. Afterward, the flow cytometry was used to assess the effects of L233 on cell cycle distribution. As for the detection of cell apoptosis upon L233 treatment, the Hoechst 33342 staining, flow cytometry, and western blotting assays were all put into practice.

RESULTS

We find that L233 inhibits tumor cell growth more efficiently and safely than cisplatin. Moreover, it is a DNA-damaging agent, interrupting the cell cycle G1/S checkpoint transition and inducing cell apoptosis by not only activating ATM/CHK1 signaling pathway, but also targeting CHK1 to reduce the expression of RAP80 and PARP-1 to compromise the DNA damage repair in tumor cells.

CONCLUSIONS

In summary, L233 is a promising anticancer drug for the development of novel chemotherapies in the future.