Zinc as a potential regulator of the BCR-ABL oncogene in chronic myelocytic leukemia cells.

BACKGROUND: Generally, decreased zinc in the serum of tumor patients but increased zinc in tumor cells can be observed. However, the role of zinc homeostasis in myeloid leukemia remains elusive. BCR-ABL is essential for the initiation, maintenance, and progression of chronic myelocytic leukemia (CML). We are currently investigating the association between zinc homeostasis and CML. METHODS: Genes involved in zinc homeostasis were examined using three GEO datasets. Western blotting and qPCR were used to investigate the effects of zinc depletion on BCR-ABL expression. Furthermore, the effect of TPEN on BCR-ABL promoter activity was determined using the dual-luciferase reporter assay. MRNA stability and protein stability of BCR-ABL were assessed using actinomycin D and cycloheximide. RESULTS: Transcriptome data mining revealed that zinc homeostasis-related genes were associated with CML progression and drug resistance. Several zinc homeostasis genes were affected by TPEN. Additionally, we found that zinc depletion by TPEN decreased BCR-ABL mRNA stability and transcriptional activity in K562 CML cells. Zinc supplementation and sodium nitroprusside treatment reversed BCR-ABL downregulation by TPEN, suggesting zinc- and nitric oxide-dependent mechanisms. CONCLUSION: Our in vitro findings may help to understand the role of zinc homeostasis in BCR-ABL regulation and thus highlight the importance of zinc homeostasis in CML.

Suppression of MIF-induced neuronal apoptosis may underlie the therapeutic effects of effective components of Fufang Danshen in the treatment of Alzheimer's disease.

Fufang Danshen (FFDS or Compound Danshen) consists of three Chinese herbs Danshen (Salviae miltiorrhizae radix et rhizome), Sanqi (Notoginseng radix et rhizome) and Tianranbingpian (Borneolum, or D-borneol), which has been show to significantly improve the function of the nervous system and brain metabolism. In this study we explored the possible mechanisms underlying the therapeutic effects of the combination of the effective components of FFDS (Tan IIA, NG-R1 and Borneol) in the treatment of Alzheimer's disease (AD) based on network pharmacology. We firstly constructed AD-related FFDS component protein interaction networks, and revealed that macrophage migration inhibitory factor (MIF) might regulate neuronal apoptosis through Bad in the progression of AD. Then we investigated the apoptosis-inducing effects of MIF and the impact of the effective components of FFDS in human neuroblastoma SH-SY5Y cells. We observed the characteristics of a "Pendular state" of MIF, where MIF (8 ng/mL) increased the ratio of p-Bad/Bad by activating Akt and the IKKα/ß signaling pathway to assure cell survival, whereas MIF (50 ng/mL) up-regulated the expression of Bad to trigger apoptosis of SH-SY5Y cells. MIF displayed neurotoxicity similar to Aß1-42, which was associated with the MIF-induced increased expression of Bad. Application of the FFDS composite solution significantly decreased the expression levels of Bad, suppressed MIF-induced apoptosis in SH-SY5Y cells. In a D-galactose- and AlCl3-induced AD mouse model, administration of the FFDS composite solution significantly improved the learning and memory, as well as neuronal morphology, and decreased the serum levels of INF-γ. Therefore, the FFDS composite solution exerts neuroprotective effects through down-regulating the level of Bad stimulated by MIF.

Small molecule RL71 targets SERCA2 at a novel site in the treatment of human colorectal cancer.

While targeted agents are an important part of the treatment arsenal for colorectal cancer, there is still a lack of efficient small-molecule targeted agents based on the understanding of pathogenic molecular mechanisms. In this study, curcumin analog RL71 displayed potent cytotoxicity towards human colon cancer cells with an IC50 of 0.8 µM in SW480 cells and inhibited xenotransplanted tumor growth in a dose-dependent manner. Using affinity chromatography, we identified sarco/endoplasmic reticulum calcium-ATPase (SERCA) 2 as the binding target of RL71. Most notably, RL71 demonstrated special binding to SERCA2 at a novel site with the lowest estimated free energy -8.89 kcal mol(-1), and the SERCA2 residues critical for RL71 binding were identified. RL71 suppressed the Ca(2+)-ATPase activity of SERCA2 both in vitro and in vivo, accompanied by the induction of endoplasmic reticulum stress leading to apoptosis and G2/M cycle arrest in SW480 cells. In addition, RL71 showed synergistic cytotoxicity with the pan-SERCA inhibitor thapsigargin. These results suggest that RL71 could be a selective small-molecule inhibitor of SERCA2, and that it may serve as a lead compound for the study of targeted colorectal cancer therapy.

Thioredoxin glutathione reductase as a novel drug target: evidence from Schistosoma japonicum.

BACKGROUND: Schistosomiasis remains a major public health concern affecting billions of people around the world. Currently, praziquantel is the only drug of choice for treatment of human schistosomiasis. The emergence of drug resistance to praziquantel in schistosomes makes the development of novel drugs an urgent task. Thioredoxin glutathione reductase (TGR) enzymes in Schistosoma mansoni and some other platyhelminths have been identified as alternative targets. The present study was designed to confirm the existense and the potential value of TGR as a target for development of novel antischistosomal agents in Schistosoma japonicum, a platyhelminth endemic in Asia. METHODS AND FINDINGS: After cloning the S. japonicum TGR (SjTGR) gene, the recombinant SjTGR selenoprotein was purified and characterized in enzymatic assays as a multifunctional enzyme with thioredoxin reductase (TrxR), glutathione reductase (GR) and glutaredoxin (Grx) activities. Immunological and bioinformatic analyses confirmed that instead of having separate TrxR and GR proteins in mammalian, S. japonicum only encodes TGR, which performs the functions of both enzymes and plays a critical role in maintaining the redox balance in this parasite. These results were in good agreement with previous findings in Schistosoma mansoni and some other platyhelminths. Auranofin, a known inhibitor against TGR, caused fatal toxicity in S. japonicum adult worms in vitro and reduced worm and egg burdens in S. japonicum infected mice. CONCLUSIONS: Collectively, our study confirms that a multifunctional enzyme SjTGR selenoprotein, instead of separate TrxR and GR enzymes, exists in S. japonicum. Furthermore, TGR may be a potential target for development of novel agents against schistosomes. This assumption is strengthened by our demonstration that the SjTGR is an essential enzyme for maintaining the thiol-disulfide redox homeostasis of S. japonicum.