Fluacrypyrim, a novel STAT3 activation inhibitor, induces cell cycle arrest and apoptosis in cancer cells harboring constitutively-active STAT3.

STAT3 protein has an important role in oncogenesis and is a promising anticancer target. Herein, we demonstrate that a novel small molecule fluacrypyrim (FAPM) inhibits the growth of leukemia cells by a predominant G1 arrest with significant decrease of the protein and mRNA levels of cyclin D1. As cyclin D1 is transcriptionally regulated by STAT3, FAPM is then shown to markedly inhibit the STAT3 phosphorylation with marginal effect on the other signal transducers and activators of transcription, and without effect on phosphoinositide-3-kinase and mitogen-activated protein kinase pathways. Further analysis shows that FAPM significantly increases the protein tyrosine phosphatases (PTPs) activity in a dose-dependent manner, and the inhibition of PTP activation by sodium pervanadate reverses FAPM-induced suppression of STAT3 tyrosine phosphorylation, indicating an important role of PTP in the action of FAPM. Finally, FAPM treatment results in selective suppression of STAT3-mediated transcriptional activity and its downstream effectors, and subsequent induction of growth arrest and apoptosis in STAT3-dependent cancer cell lines. This study therefore identifies FAPM as a potent STAT3 activation inhibitor with possible therapeutic potential against malignancies with constitutive STAT3 activation.

[Identification of differentially expressed genes of acute hypoxia-treated HepG2 cells and hypoxia-acclimatized HepG2 cells].

To provide necessary information for further understanding of molecular mechanism of hypoxia acclimatization, the differentially expressed genes of HepG2 cells exposed to normoxia, acute hypoxia-treated cells which were exposed to 1% oxygen for 48 h, and hypoxia-acclimatized HepG2 cells which were cultured for 6 circles of alternate low oxygen (1% oxygen for 24 h) and normal oxygen (21% oxygen for 24 h), were identified respectively by combining the suppression subtractive hybridization (SSH) and cDNA microarray. Thirty-seven genes were expressed differentially in cells exposed to 1% oxygen for 48 h compared with those in cells exposed to normoxia. The expression of all these 37 genes was down-regulated, including the genes participating in cell cycle, cell response to stimulus, and cell signal transduction, and cell cytoskeleton formation, the genes associated with transcription and cell metabolism, 4 expressed sequence tags (ESTs), and 12 genes of which the functions are not known. There is a novel gene sequence, which has not been found in existing databases. There were only 6 genes differentially expressed in the hypoxia-acclimatized cells compared with cells exposed to normoxia, including two mitochondrion genes, metalloprotease-1 gene, ferritin gene, thymosin beta-4 and TPT1 genes. The expressions of mitochondrion ND4, ferritin, thymosin beta-4 and TPT1 were up-regulated, while the expressions of mitochondrion ND1 gene and metalloproease-1 gene were down-regulated. Cell tolerance to hypoxia increased after the cells were hypoxia-acclimatized. The different gene expression patterns of the acute hypoxia-treated cells and the hypoxia-acclimatized cells may be related to the increased tolerance of the cells to hypoxia.

High dose granulocyte colony-stimulating factor enhances survival and hematopoietic reconstruction in canines irradiated by 2.3 Gy mixed fission neutron and gamma ray.

This study was purposed to evaluate the effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on hematopoietic reconstruction and survival in beagles exposed to mixed fission neutron and γ-ray. 13 beagles were unilaterally exposed to single dose of 2.3 Gy 90% neutrons. The experiments were divided into 3 groups: irradiation control group (no any treatment, n = 4), supportive care group (n = 5) and rhG-CSF plus supportive care group (n = 4, abbreviated as rhG-CSF group) in which the beagles were subcutaneously injected with 200 µg/kg of rhG-CSF early at half an hour and 24 hours post-irradiation respectively. The results showed that 2.3 Gy 90% neutron irradiation induced a severe acute radiation sickness of bone marrow type. The administration of rhG-CSF increased the survival rate from 60% in supportive care group to 100%. Twice injection of rhG-CSF in the first 24 hours reduced duration of neutropenia, enhanced neutrophil nadir and promoted neutrophil recovery when compared with control cohort administered clinical support. The number of colony-forming cells (CFU-GM, CFU-E, and BFU-E) in peripheral blood of rhG-CSF treated canines increased 2-to 5-fold relative to those of the supportive care group on day 3. All canines treated with rhG-CSF achieved hematopoietic reconstruction as evidenced by the pathological section of sternum while severe shortage of hemopoietic cells remained in the cohorts given supportive care alone. It is concluded that the combination of supportive care and high-dose rhG-CSF can accelerate hematopoietic recovery and enhance survival of dogs exposed to 2.3 Gy mixed neutron and gamma ray.

RhG-CSF improves radiation-induced myelosuppression and survival in the canine exposed to fission neutron irradiation.

Fission-neutron radiation damage is hard to treat due to its critical injuries to hematopoietic and gastrointestinal systems, and so far few data are available on the therapeutic measures for neutron-radiation syndrome. This study was designed to test the effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in dogs which had received 2.3 Gy mixed fission-neutron-γ irradiation with a high ratio of neutrons (~90%). Following irradiation, rhG-CSF treatment induced 100% survival versus 60% in controls. Only two of five rhG-CSF-treated dogs experienced leukopenia (white blood cells [WBC] count < 1.0 × 10(9)/L) and neutropenia (neutrophil [ANC] count < 0.5 × 10(9)/L), whereas all irradiated controls displayed a profound period of leukopenia and neutropenia. Furthermore, administration of rhG-CSF significantly delayed the onset of leukopenia and reduced the duration of leucopenia as compared with controls. In addition, individual dogs in the rhG-CSF-treated group exhibited evident differences in rhG-CSF responsiveness after neutron-irradiation. Finally, histopathological evaluation of the surviving dogs revealed that the incidence and severity of bone marrow, thymus and spleen damage decreased in rhG-CSF-treated dogs as compared with surviving controls. Thus, these results demonstrated that rhG-CSF administration enhanced recovery of myelopoiesis and survival after neutron-irradiation.

[Effect of rhG-CSF on blood coagulation in beagles irradiated by 2.3 Gy neutron].

The aim of this study was to investigate the effect of recombinant human granulocyte stimulating factor (rhG-CSF) on blood coagulation of beagles irradiated by 2.3 Gy neutron so as to provide new therapy for blood coagulation disorder after neutron irradiation. 10 beagles were exposed to 2.3 Gy neutron, and then randomly assigned into supportive care group and rhG-CSF-treated group. The rhG-CSF-treated cohorts were injected subcutaneously with rhG-CSF (10 µg/kg·d) beginning at the day of exposure for 21 consecutive days. Peripheral blood platelet counts were examined once every two days. In vitro platelet aggregation test, thromboelastography and blood clotting tetrachoric tests were also performed. The results indicated that the blood clotting system of irradiated dogs was in hypercoagulable state in the early days after 2.3 Gy neutron irradiation, and became hypocoagulable at crisis later and were mainly on intrinsic coagulation pathway. Blood fibrinogen increased markedly during the course of disease, while platelet counts and aggregation function were decreased remarkably. rhG-CSF administered daily could correct hypercoagulable state induced by 2.3 Gy neutron irradiation at the early time post exposure, shortened the thromboplastin generation time and clotting formation, down-regulated the abnormal high fibrinogen in blood, and improved platelet aggregation function. It is concluded that rhG-CSF can improve coagulation disorders of irradiated dogs.

Structural requirement of spirostanol glycosides for rat uterine contractility and mode of their synergism.

OBJECTIVES: Total steroidal saponins extracted from the rhizome of Paris polyphylla (TSSP) have been used in China for the treatment of abnormal uterine bleeding. The aim of this study was to analyse the structure-activity relationship of steroidal saponins purified from P. polyphylla Sm. var. yunnanensis on rat myometrial contractions, and investigate the synergism among themselves as well as with known inherent agonists, such as Prostaglandin F(2alpha) (PGF-2alpha). METHODS: In this study, 22 steroidal saponins purified from TSSP were screened for their contractile activity in isolated uterine strips from estrogen-primed rats. KEY FINDINGS: It was shown that spirostanol glycosides exhibited inducible or inhibitory activity in rat uterine contraction based on the difference of their structures, which was not only attributed in part to the number, the length and the position of sugar side chains attached by a glycoside, but also related to the structure of the aglycone. Furthermore, synergistic actions were observed among pennogenin or diosgenin glycosides as well as with the known inherent agonist PGF-2alpha, indicating they may share, at least in part, similar pathways with PGF-2alpha in stimulating myometrial contractions. Finally, the contractile response of rat myometrium to spirostanol glycosides was significantly enhanced with advancing pregnancy. CONCLUSIONS: Together, these data support the possibility that some spirostanol glycosides may represent a new type of contractile agonist for the uterus and their synergism may be responsible for the therapeutic effect of TSSP on abnormal uterine bleeding.

Melissoidesin G, a diterpenoid purified from Isodon melissoides, induces leukemic-cell apoptosis through induction of redox imbalance and exhibits synergy with other anticancer agents.

Melissoidesin G (MOG) is a new diterpenoid purified from Isodon melissoides, a plant used in Chinese traditional medicine as antitumor and anti-inflammatory agents. In our study, MOG was shown to specifically inhibit the growth of human leukemia cell lines and primary acute myeloid leukemia (AML) blasts via induction of apoptosis, with the evidence of mitochondrial DeltaPsim loss, reactive oxygen species production, caspases activation and nuclear fragmentation. Furthermore, it was shown that thiol-containing antioxidants completely blocked MOG-induced mitochondrial DeltaPsim loss and subsequent cell apoptosis, while the inhibition of apoptosis by benzyloxy-carbonyl-Val-Ala-Asp-fluoromethylketone only partially attenuated mitochondrial DeltaPsim loss, indicating that MOG-induced redox imbalance is an early event upstream to mitochondrial DeltaPsim loss and caspase-3 activation. Consistently, it was found that MOG rapidly decreased the intracellular glutathione (GSH) content in a dose-dependent manner and the significance of GSH depletion in MOG-induced apoptosis was further supported by the protective effects of tert-butylhydroquinone (tBHQ) and the facilitative effects of DL-buthionine (S,R)-sulfoximine (BSO). Furthermore, it was showed that GSH depletion induced by MOG rendered some leukemia cell lines more sensitive to arsenic trioxide (As2O3), doxorubicin or cisplatin. Additionally, the synergistic apoptotic effects of MOG with As2O3 were detected in HL-60 and primary AML cells, but not in normal cells, suggesting the selective toxicity of their combination to the malignant cells. Together, we proposed that MOG alone or administered with other anticancer agents may provide a novel therapeutic strategy for leukemia.

Molecular cloning and characterization of cDNA encoding fibrinolytic enzyme-3 from earthworm Eisenia foetida.

The earthworm fibrinolytic enzyme-3 (EFE-3, GenBank accession No: AY438622), from the earthworm Eisenia foetida, is a component of earthworm fibrinolytic enzymes. In this study, cDNA encoding the EFE-3 was cloned by RT-PCR. The cDNA contained an open reading frame of 741 nucleotides, which encoded a deduced protein of 247 amino acid residues, including signal sequences. EFE-3 showed a high degree of homology to earthworm (Lumbricus rebullus) proteases F-III-1, F-III-2, and bovine trypsin. The recombinant EFE-3 was expressed in E. coli as inclusion bodies, and the gene encoding the native form of EFE-3 was expressed in COS-7 cells in the medium. Both the refolding product of inclusion bodies and the secreted protease could dissolve the artificial fibrin plate.

[The effects of rhG-CSF and rhSCF on peripheral blood leukocytes and CFU-GM in rhesus monkeys].

To evaluate the effects of rhG-CSF and rhSCF on mobilization of the peripheral blood stem cells, 15 monkeys were divided into control, rhG-CSF 10 micro g/(kg x day) and rhG-CSF 10 micro g/(kg x day) + rhSCF 50 micro g/(kg x day) treated groups. Monkeys were administered with vehicle, rhG-CSF and rhG-CSF + rhSCF subcutaneously once daily for 14 days, respectively. The results showed that the highest counts of leukocyte of rhG-CSF treated group were 411% of baseline value on day 7 after administration, compared with that of rhG-CSF + rhSCF treated group which were 538% on day 9. The highest counts of leukocytes lasted for 3 days in combined treated group. CFU-GM from peripheral blood in the two groups were 8.37 and 11.75 times higher at 5 and 9 days respectively after the mobilization. It is concluded that rhG-CSF significantly increases the number of peripheral blood leukocytes and CFU-GM, and a better effect can be obtained by rhSCF + rhG-CSF combined administration.