Notch signaling pathway and cancer metastasis

Cancer metastasis is the leading cause of cancer-related deaths all over the world at present. Accumulated researches have demonstrated that cancer metastasis is composed of a series of successive incidents, mainly including epithelial-mesenchymal transition (EMT), malignant cell migration, resistance to anoikis, and angiogenesis and lymphangiogenesis processes. However, the complicated cellular and molecular mechanisms underlying and modulating these processes have not been well elucidated. Thus, studies on cancer metastasis mechanism may propose possibilities to therapeutically interfere with signaling pathways required for each step of cancer metastasis, therefore inhibiting the outgrowth of distant metastasis of tumors. Recent insights have linked the Notch signaling pathway, a critical pathways governing embryonic development and maintaining tumor stemness, to cancer metastasis. This chapter highlights the current evidence for aberration of the Notch signaling in metastasis of tumors such as osteosarcoma, breast cancer, prostate cancer, and melanoma. In these studies, Notch activity seems to participate in cancer metastasis by modulating the EMT, tumor angiogenesis processes, and the anoikis-resistance of tumor cells. Therefore, manipulating Notch signaling may represent a promising alternative/ complement therapeutic strategy targeting cancer metastasis besides cancer stemness.

[Clinical analysis of peripheral blood stem cell mobilization regimens in autologous transplantation for treating non-Hodgkin's lymphoma]

The purpose of this study was to compare the efficacy of CEP plus G-CSF and CVP plus G-CSF regimens in the mobilization and collection of peripheral blood hematopoietic stem cells (PBHSC), and in the hematopoietic recovery. 57 patients with non-Hodgkin's lymphoma (NHL) underwent autologous PBHSC transplantation were analyzed retrospectively. The PBHSC were mobilized and collected by using CEP plus G-CSF and CVP plus G-CSF respectively, and were retransfused into these NHL patients after preconditioning, then the mobilization efficacy, adverse reactions and hematopoietic recovery were analyzed. The results showed that the WBC count decreased to ≤ 1.0 × 10(9)/L, platelet amount dropped to ≤ 40 × 10(9)/L during peripheral blood stem cell mobilization of all patients, which indicated successful collection of PBHSC. The mean value of (4.38 ± 3.40) × 10(8)/kg mononuclear cells (MNC) containing (2.79 ± 2.53) × 10(6)/kg CD34(+) cells were collected in CEP plus G-CSF group, while the mean value of (3.31 ± 1.23) × 10(8)/kg MNC containing (2.02 ± 0.87) × 10(6)/kg CD34(+) cells were collected in CVP plus G-CSF group. The efficacy of mobilization in CEP plus G-CSF group was significantly higher than that in CVP plus G-CSF group (p < 0.05). After preconditioning, bone marrow was suppressed in all patients. The average time of WBC count recovery to ≥ 1.0 × 10(9)/L was 11.4 days in CEP plus G-CSF group and 12.3 days in CVP plus G-CSF group; the average time of platelet amount recovery to ≥ 50 × 10(9)/L was 18.6 days in CEP plus G-CSF group and 19.3 days in CVP plus G-CSF group. The statistical analysis showed no significant difference in the average time of hematopoietic recovery between 2 groups. It is concluded that autologous PBHSC transplantation shows significant effect for treatment of patients with NHL. Either modified CEP or CVP plus G-CSF regimen is safe and effective in PBHSC mobilization. The CEP plus G-CSF regimen is better than CVP plus G-CSF regimen.

The hypoglycemic activity of Lithocarpus polystachyus Rehd. leaves in the experimental hyperglycemic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Leaves of Lithocarpus polystachyus Rehd. are used for the treatment of disorders such as diabetes, hypertension, and epilepsy in folk medicine of South China. The possible antidiabetic effects of the leaves were investigated in experimental type 2 and type 1 diabetic rats.

MATERIALS AND METHODS

Type 2 diabetic rats received orally three different extracts of Lithocarpus polystachyus Rehd. leaves for 4 weeks (aqueous extract [ST-1], ethanol extract [ST-2], flavonoid-rich fraction [ST-3]). At the end of the experiment biochemical parameters were tested and livers and pancreases were excised for histological study. After the comparison of the pharmacological test results of the three extracts, the one which showed the best bioactivity was further studied to confirm its antidiabetes effect on both type 2 and type 1 diabetic rats.

RESULTS

Compared to ST-1 and ST-2, ST-3 had better effects on regulation of blood glucose, glycosylated serum protein, cholesterol, triglyceride, malondialdehyde, superoxide dismutase and attenuation of liver injury in type 2 diabetic rats (p<0.01 or p<0.05). ST-3 administration for four weeks also significantly reduced the fasting serum insulin and C-peptide level and improved the insulin tolerance (p<0.05). In type 1 diabetic rats, ST-3 supplement for three weeks caused significant reduction in fasting blood glucose, total cholesterol, triglyceride, urea nitrogen, creatinine and liver mass, along with significantly inhibiting the decline of insulin level compared to diabetic control (p<0.05 or p<0.01).

CONCLUSION

The flavonoid-rich fraction of Lithocarpus polystachyus Rehd. leaves (ST-3) had better beneficial effect than that of the ethanol or aqueous extract in experimental diabetic rats, which means that the bioactivity of the herbal leaves is probably due to the presence of flavonoids. The results also strongly suggest that the antidiabetic effect of ST-3 was possibly through multiple mechanisms of action including blood lipid and antioxidant mediation. The results indicated that the aqueous flavonoid-rich fraction of Lithocarpus polystachyus Rehd. leaves possessed significant protective activity in type 2 and type 1 diabetes.

Biochemical characterization of the cell-biomaterial interface by quantitative proteomics

Surface topography and texture of cell culture substrata can affect the differentiation and growth of adherent cells. The biochemical basis of the transduction of the physical and mechanical signals to cellular responses is not well understood. The lack of a systematic characterization of cell-biomaterial interaction is the major bottleneck. This study demonstrated the use of a novel subcellular fractionation method combined with quantitative MS-based proteomics to enable the robust and high-throughput analysis of proteins at the adherence interface of Madin-Darby canine kidney cells. This method revealed the enrichment of extracellular matrix proteins and membrane and stress fibers proteins at the adherence surface, whereas it shows depletion of extracellular matrix belonging to the cytoplasmic, nucleus, and lateral and apical membranes. The asymmetric distribution of proteins between apical and adherence sides was also profiled. Apart from classical proteins with clear involvement in cell-material interactions, proteins previously not known to be involved in cell attachment were also discovered.

[Role of Delta-like 1 in differentiation and antigen presentation of mouse bone marrow-derived dendritic cells]

The aim of this study was to investigate the role of Delta-like 1 (Dll1) in differentiation and antigen pre-sensation of mouse bone marrow-derived dendritic cells (DCs). In the presence of granulocyte macrophage colony stimulating factor (GM-CSF) and interleukin 4 (IL-4), mouse bone marrow cells were co-cultured with OP9-Dll1 and OP9-GFP cell lines respectively. After 8 days, the immature DCs were stimulated with tumor antigen. The surface molecules of the activated DCs including MHC II, CD80 and CD86 were analyzed by flow cytometry. Levels of IL-12 and IL-10 in the culture supernatant were detected by ELISA. In addition, the proliferation of T-cells co-cultured with DCs was analyzed by FACS through mixed T-lymphocyte reaction. The results showed that compared with OP9-GFP, the bone marrow cells co-cultured with OP9-Dll1 produced significantly more CD11c(+) DCs (p < 0.05), and possessed higher levels of surface molecule expression including MHC II, CD80 and CD86 after tumor antigen stimulation. The DCs secreted higher level of IL-12 (p < 0.05) and less IL-10 (p < 0.01). They also resulted in significantly stronger T-cell proliferation response. It is concluded that Dll1 can promote the differentiation of DCs from mouse bone marrow cells and enhance their antigen presentation capacity.

Notch signaling determines the M1 versus M2 polarization of macrophages in antitumor immune responses

Macrophages are important tumor-infiltrating cells and play pivotal roles in tumor growth and metastasis. Macrophages participate in immune responses to tumors in a polarized manner: classic M1 macrophages produce interleukin (IL) 12 to promote tumoricidal responses, whereas M2 macrophages produce IL10 and help tumor progression. The mechanisms governing macrophage polarization are unclear. Here, we show that the M2-like tumor-associated macrophages (TAM) have a lower level of Notch pathway activation in mouse tumor models. Forced activation of Notch signaling increased M1 macrophages which produce IL12, no matter whether M1 or M2 inducers were applied. When Notch signaling was blocked, the M1 inducers induced M2 response in the expense of M1. Macrophages deficient in canonical Notch signaling showed TAM phenotypes. Forced activation of Notch signaling in macrophages enhanced their antitumor capacity. We further show that RBP-J-mediated Notch signaling regulates the M1 versus M2 polarization through SOCS3. Therefore, Notch signaling plays critical roles in the determination of M1 versus M2 polarization of macrophages, and compromised Notch pathway activation will lead to the M2-like TAMs. These results provide new insights into the molecular mechanisms of macrophage polarization and shed light on new therapies for cancers through the modulation of macrophage polarization through the Notch signaling.

Lipopolysaccharide-induced maturation of bone marrow-derived dendritic cells is regulated by notch signaling through the up-regulation of CXCR4

Dendritic cells (DCs) are professional antigen presenting cells to initiate immune response against pathogens, but mechanisms controlling the maturation of DCs are unclear. Here we report that, in the absence of recombination signal binding protein-Jkappa (RBP-J, the transcription factor mediating Notch signaling), lipopolysaccharide-stimulated monocyte-derived DCs are arrested at a developmental stage with few dendrites, low major histocompatibility complex II (MHC II) expression, and reduced motility and antigen presentation ability. RBP-J null DCs had lower expression of CXCR4. Transduction with a CXCR4-expressing lentivirus rescued developmental arrest of RBP-J-deficient DCs. Activation of Notch signaling in DCs up-regulated CXCR4 expression and increased the outgrowth of dendrites and the expression of MHC II. These effects were abrogated by a CXCR4 inhibitor. Therefore, Notch signaling is essential for DCs to transit from a dendrite(low)MHC II(low) immature state into a dendrite(high)MHC II(high) mature state, during the lipopolysaccharide-induced DC maturation, most likely through the up-regulation of CXCR4.

Disruption of the transcription factor recombination signal-binding protein-Jkappa (RBP-J) leads to veno-occlusive disease and interfered liver regeneration in mice

Liver sinusoid (LS) endothelial cells (LSECs) support hepatocytes in resting livers and proliferate during liver regeneration to revascularize regenerated liver parenchyma. We report that recombination signal-binding protein-Jkappa (RBP-J), the critical transcription factor mediating Notch signaling, regulates both resting and regenerating LSECs. Conditional deletion of RBP-J resulted in LSEC proliferation and a veno-occlusive disease-like phenotype in the liver, as manifested by liver congestion, deposition of fibrin-like materials in LSs, edema in the space of Disse, and increased apoptosis of hepatocytes. Regeneration of liver was remarkably impaired, with reduced LSEC proliferation and destroyed sinusoidal structure. LSEC degeneration was obvious in the regenerating liver of RBP-J-deficient mice, with some LSECs losing cytoplasm, and organelles protruding into the remnant plasma-membrane of LSs to hamper the microcirculation and intensify veno-occlusive disease during liver regeneration. Hepatocytes were also degenerative, as shown by dilated endoplasmic reticulum, decreased proliferation, and increased apoptosis during liver regeneration. Molecular analyses revealed that the dynamic expression of several related molecules-such as vascular endothelial growth factor, vascular endothelial growth factor receptors 1 and 2, interleukin-6, and hepatocyte growth factor-was disturbed.

CONCLUSION

Notch/RBP-J signaling may play dual roles in LSECs: in resting liver it represses proliferation, and in regenerating liver it supports proliferation and functional differentiation.

[Research advance of notch signal in ex vivo expansion of hematopoietic progenitor cells - review]

Ex vivo expansion of hematopoietic progenitor cells (HPCs) is valuable for clinical application, however, traditional ex vivo culture negatively affects long-term hematopoietic reconstitution ability. In the hematopoietic system, the expression of Notch receptors and their ligands has been widely reported. Active Notch signal inhibits the differentiation of HSCs while promotes their expansion, suggesting that ex vivo expansion of hematopoietic progenitor cells could be enhanced by manipulating Notch signal pathways. In this article the Notch signal pathways, Notch signal and maintenance of hematopoietic progenitor cells, Notch signal and expansion of hematopoietic progenitor cells and molecular mechanism of Notch signal maintaining undifferentiation of hematopoietic progenitor cells were reviewed.

[Construction and expression of a fusion protein containing extracellular domain of human Jagged1 and Fc fragment of human IgG1 in Pichia Pastoris]

In order to construct a pichia pastoris expression vector containing the extracellular domain of human Jagged1 and the Fc fragment of human IgG1 fusion gene, or containing only the Fc fragment of human IgG1 and to express them in pichia pastoris. The extracellular domain of human Jagged1 gene was cloned from normal human bone marrow cells. After DNA sequencing, the extracellular domain of Jagged1 gene was inserted into pIC-Fc vector constructed previously, which is Pichia pastoris expression vector containing only the Fc fragment of human IgG1. The constructed plasmid was transformed into yeast GS115 by means of electroporation. The recombinant transformants with a high copy number of the plasmid were selected on MD plate with G418. The expression of protein was induced by addition of methanol. Then, protein expression was analyzed by SDS-PAGE. The results indicated that the extracellular domain of human Jagged1 gene was effectively amplified. The DNA sequencing result showed that the constructed plasmid containing hJagged1(ext)-Fc fusion gene was the same as designed. The fusion protein was successfully expressed in Pichia pastoris. It is concluded that the hJagged1(ext) gene has been successfully cloned and expressed, which provides a new fusion protein for further experiments, the hJagged1(ext)-Fc fusion protein can be used as a new stimulator for proliferation of hematopoietic stem/progenitor cells in vitro.

Multiple primary primitive neuroectodermal tumours within the spinal epidural space with non-concurrent onset

A case of multiple primary primitive neuroectodermal tumours (PNETs), which occurred at different levels of the spinal epidural space successively over a period of 8 months, is reported. A 24-year-old male, presenting with rapidly progressive paralysis, hyperthesia and a posterior epidural mass extending from T8 to T10 revealed by magnetic resonance imaging (MRI), exhibited a good recovery after initial emergency surgery. Lower back pain, chest pain and paralysis were subsequently reported. Spinal MRI in month 7 revealed a mass extending from T12 to L1 and another mass extending from T4 to T5 was detected epidurally in month 8. Additional operations were performed and radiotherapy was given. Pathological findings were consistent with PNETs and symptoms improved with treatment, particularly following each surgical excision.

Expression, refolding, and purification of a truncated human Delta-like1, a ligand of Notch receptors

The Notch signaling pathway plays a pivotal role in proliferation, apoptosis, and cell fate specification in both embryonic and postnatal development, and is a potential therapeutic target for human diseases such as cancer. To express in Escherichia coli and purify soluble fragment of human Delta-like1 (hDll1), we cloned two extracellular fragments of hDll1 [hDll1 (127-225) and hDll1 (26-225)]. The hDll1 (127-225) fragment was successfully expressed in E. coli as a GST fusion protein (GST-hDll1). The GST-hDll1 protein, which was expressed as inclusion bodies after induction by IPTG, was refolded and purified simultaneously using affinity chromatography and size exclusion chromatography. The purified GST-hDll1 was of more than 95% purity, and had a molecular weight of 39kDa. Reporter assay showed that GST-hDll1 could activate a reporter gene that is dependent on Notch activation. Therefore, using the E. coli expression system and different chromatography systems, we successfully expressed, refolded, and purified a biologically active GST-hDll1, which might be potentially useful for therapy and studying the Notch pathway.

RBP-J, the transcription factor downstream of Notch receptors, is essential for the maintenance of vascular homeostasis in adult mice

In adults, angiogenic abnormalities are involved in not only tumor growth but several human inherited diseases as well. It is unclear, however, concerning how the normal vascular structure is maintained and how angiogenesis is initiated in normal adults. Using the Cre-LoxP-mediated conditional gene deletion, we show in the present study that in adult mice disruption of the transcription factor recombination signal-binding protein Jkappa (RBP-J) in endothelial cells strikingly induced spontaneous angiogenesis in multiple tissues, including retina and cornea, as well as in internal organs, such as liver and lung. In a choroidal neovascularization model, which mimics the angiogenic process in tumor growth and age-related macular degeneration, RBP-J deficiency induced a more intensive angiogenic response to injury. This could be transmitted by bone marrow, indicating that RBP-J could modulate bone marrow-derived endothelial progenitor cells in adult angiogenesis. In addition, in the absence of RBP-J, proliferation of endothelial cells increased significantly, leading to accumulative vessel outgrowth. These findings suggest that in adults RBP-J-mediated Notch signaling may play an essential role in the maintenance of vascular homeostasis by repressing endothelial cell proliferation.

Reduction of blood pressure with calcium and potassium supplementation in children with salt sensitivity: a 2-year double-blinded placebo-controlled trial

An investigation of the reductive effect of blood pressure and increment of urinary sodium excretion with calcium and potassium supplementation in children with sodium sensitivity is conducted. In total of 261 school children who had completed a 2-year double-blinded, placebo-controlled trial with calcium and potassium supplementation salt sensitivity, with a salt volume expansion and contraction protocol, was determined. The results showed that in children with salt sensitivity, the increase in blood pressure in the supplementary group was lower by 4.3/4.8 mmHg than that in the placebo group (P<0.05), while no significant change was found between the supplementary group and placebo group in children with nonsalt sensitivity. With calcium and potassium supplementation, the night urinary sodium excretion in children with salt sensitivity was significantly increased (P<0.01), and it is negatively correlated with the increase in blood pressure. It was suggested that a moderate increase of calcium and potassium intake in children with salt sensitivity, through interaction with sodium, can promote urinary sodium excretion and may play contribute to the prevention of hypertension.

Effects of intravascular perfusion of cooled crystalloid solution on cold-induced brain injury using an extracorporeal cooling-filtration system

BACKGROUND

We evaluated cerebral metabolic change during brain hypothermia with intravascular perfusion of cooled crystalloid solution using an extracorporeal cooling-filtration system and cerebroprotective effects of this hypothermia on brain injury in an animal model.

METHOD

Microdialysis probes were implanted into the bilateral parietal cortices. A cold-induced brain injury was produced behind the microdialysis probe on the right parietal cortex. Immediately after injury in the cooled group (n=9), Ringer's solution cooled to 5 degrees C was infused into the right vertebral artery after occlusion of the bilateral common carotid and the left vertebral arteries. Excessive fluid was ultrafiltrated by a dialyzer. Brain temperature was maintained at about 20 degrees C for 60 minutes. In 7 dogs, three neck arteries were occluded for 60 minutes after injury without cooled fluid infusion. The extracellular concentrations of glutamate, lactate, and pyruvate were measured serially for 180 minutes after injury.

FINDINGS

Extracellular glutamate concentrations in the cooled group did not increase, while there was a significant increase in the injured hemisphere as compared to the uninjured hemisphere in the non-cooled group ( P<0.05). Extracellular lactate concentrations increased slightly after occlusion in both groups. The depth of cortical injury was limited in the cooled group, but extended into the white matter in the non-cooled group up to 240 minutes after injury.

INTERPRETATION

Occlusion of three main arteries induced ischaemia under critical threshold in canine brains. Under this condition, intravascular cooling with crystalloid solution suppressed accumulation of extracellular glutamate and reduced tissue damage in the early phase after cold-induced brain injury, as cerebroprotective effects. This information suggests that a method employing brain hypothermia via intra-arterial cooling with an extracorporeal cooling-filtration system has potential to achieve successful, safe, selective brain cooling.

[Activation effects of BCR/ABL antigen on CML T cells mediated by protein transduction domain]

AIM

To study the activation effect of BCR/ABL antigen on T cells from CML patients mediated by protein transduction domain (PTD).

METHODS

The fused plasmid containing PTD gene and b3a2 bcr/abl gene of CML was constructed by genetic engineering technique and was expressed in E.coli. The PBMCs from CML patients were stimulated in-vitro with purified PTD-BCR/ABL antigen and then expression of the activation antigen CD25 on CD8(+) and CD4(+) T cells after stimulation was detected by flow cytometry (FCM).

RESULTS

After stimulation with 100 mg/L of PTD-BCR/ABL antigen (final concentration) for 4 days in-vitro, CD8(+) T cells were activated in 5 of 10 CML patients and CD4(+) T cells were activated in 2 of 10 patients. Both CD8(+) and CD4(+) T cells were activated simultaneously in one of them. However, neither CD4(+) nor CD8(+) T cells was activated in BCR/ABL antigen stimulation group as control.

CONCLUSION

Using a PTD-mediated antigen transduction system, exogenous BCR/ABL antigen can be transferred into APCs and be processed and presented onto surface of APCs to activate Ag-specific CD8(+) and CD4(+) T cells in-vitro. The strategy outlined in this paper may provide a new approach for priming Ag-specific CD8(+) and CD4(+) T cells in-vitro and immunotherapy of CML.

The structure dependent electrochemical-response of novel 1-(4-mercaptobutyl)-4-(2-ferrocenylvinyl)pyridinium bromide SAMs on an au electrode

The 1-(4-mercaptobutyl)-4-(2-ferrocenylvinyl)pyridinium bromide (1-HS(CH2)(4)-4-[(E)-FcCH=CH]C5H4N)+Br- and its hydrogenated product [1-HS(CH2)(4)-4-(-FcCH2CH2)C5H4N]+Br- were synthesized and assembled on an Au electrode to form self-assembled monolayers which showed a structure-dependent electrochemical-response in phosphate buffer aqueous solutions (pH = 7).

[Alteration of the Cell Cycle during the Differentiation of HL-60 Cells by Induction of Retinoic Acid]

To study the alteration of the cell cycle during the differentiation of human myeloid leukemia cell line HL-60 induced with all trans-retinoic acid (RA), the flow cytometry was used to assay the various phases of cell cycle in HL-60 cells treated with RA. The results showed: (1) S + G(2)/M phase proportion kept relative invariability during the 48 hours incubation of HL-60 cells with RA, however, the proportion alteration of S-phase cells was associated with the RA concentrations. At 10(-6) mol/L RA, the proportion of S-phase cells appeared a temporarily increasing peak followed by persistent decrease of S-phase proportion. At 10(-5) mol/L RA, S-phase cell proportion only appeared the persistent decreasing tendency. (2) Re-culture of HL-60 cells without RA showed the decrease of S + G(2)/M and S-phase cells was associated with the increase of differentiated cells, but not all HL-60 cells were triggered into differentiation at the same time. Once the cells start to differentiate, even if there is no RA presence, the HL-60 cells were still differentiated until maturation. In conclusion, HL-60 cells are able to differentate and maturate after exposure to RA for a period of time. S-phase proportion is related to the concentrations of RA. Once the cells start to differentiate, even if there is no RA presence, the HL-60 cells still differentiatiated until maturation.

Purification, characterization and activation of fish muscle prokallikrein

Fish prokallikrein was isolated and characterized from skeletal muscle of the black sea bass, Centropristis striata. The prokallikrein was purified to apparent homogeneity by anion exchange perfusion chromatography and reversed phase high performance liquid chromatography. Initial identification was by its weak immunoreactivity with human tissue kallikrein antiserum. Two-dimensional gel electrophoresis and immunoblotting identified the protein as 36 kDa with a pI of 4.95-5.15. The prokallikrein was trypsin-activated to produce an approximately 36 kDa active enzyme as identified on an SDS-polyacrylamide gel overlayed with a membrane impregnated with the fluorogenic tripeptidyl substrate D-Val-Leu-Arg-7-amino-4-trifluoromethyl-coumarin. A potential dimer at 72 kDa was also enzymatically active. Bass kallikrein cleaved low molecular weight dog kininogen to release kinin peptide as determined by radioimmunoassay. The enzyme's amidolytic activity, with a pH optimum at 9.0, was inhibited by aprotinin, benzamidine, and phenylmethanesulphonyl fluoride, but not by elastatinal, soybean trypsin inhibitor, or limabean trypsin inhibitor. Polyclonal antiserum raised against the purified bass muscle prokallikrein recognized 36 kDa and 72 kDa proteins in bass heart, skeletal muscle, spleen, swimbladder, gill, and kidney by Western blot analyses. The wide distribution of immunoreactive proteins in the tissues suggests a potential physiological role for fish kallikreins in muscle contraction and/or relaxation, the regulation of local blood flow, and in osmoregulation. The detection of fish prokallikrein and its activation leads the way for an evaluation of the impact of kallikreins in fish health and disease processes and for studying the evolution of kallikreins and related serine proteinases.

Kallistatin is a potent new vasodilator

Kallistatin is a serine proteinase inhibitor which binds to tissue kallikrein and inhibits its activity. The aim of this study is to evaluate if kallistatin has a direct effect on the vasculature and on blood pressure homeostasis. We found that an intravenous bolus injection of human kallistatin caused a rapid, potent, and transient reduction of mean arterial blood pressure in anesthetized rats. Infusion of purified kallistatin (0.07-1.42 nmol/kg) into cannulated rat jugular vein produced a 20-85 mmHg reduction of blood pressure in a dose-dependent manner. Hoe 140, a bradykinin B2-receptor antagonist, had no effect on the hypotensive effect of kallistatin yet it abolished the blood pressure-lowering effect of kinin and kallikrein. Relaxation of isolated aortic rings by kallistatin was observed in the presence (ED50 of 3.4 x 10(-9) M) and in the absence of endothelium (ED50 of 10(-9) M). Rat kallikrein-binding protein, but not kinin or kallikrein, induced vascular relaxation of aortic rings. Neither Hoe 140 nor Nomega-nitro--arginine methyl ester, a nitric oxide synthase inhibitor, affected vasorelaxation induced by kallistatin. Kallistatin also caused dose-dependent vasodilation of the renal vasculature in the isolated, perfused rat kidney. Specific kallistatin-binding sites were identified in rat aorta by Scatchard plot analysis with a Kd of 0.25+/-0.07 nM and maximal binding capacity of 47.9+/-10.4 fmol/mg protein (mean+/-SEM, n = 3). These results indicate that kallistatin is a potent vasodilator which may function directly through a vascular smooth muscle mechanism independent of an endothelial bradykinin receptor. This study introduces the potential significance of kallistatin in directly regulating blood pressure to reduce hypertension.

Tissue kallikrein-binding protein reduces blood pressure in transgenic mice

The kallikrein-kinin system participates in blood pressure regulation. One of the kallikrein-kinin system components, kallikrein-binding protein, binds to tissue kallikrein and inhibits its activity in vitro. To investigate potential roles of rat kallikrein-binding protein (RKBP) in vivo, we have developed transgenic mice that express an RKBP gene under the control of the mouse metallothionein metal-responsive promoter. Expression of the transgene, RKBP, was detected in the liver, kidney, lung, heart, pancreas, salivary glands, spleen, brain, testis, and adrenal gland at the mRNA and protein levels. Systolic blood pressures of homozygous transgenic mice were 88.5 +/- 0.8 mm Hg (mean +/- S.E., n = 19, P < 0.001) for one line and 88.8 +/- 1.6 mm Hg (mean +/- S.E., n = 19, P < 0.001) for another, as compared with 100.5 +/- 0.8 mm Hg (mean +/- S.E., n = 18) for control mice. Direct blood pressure measurements of these transgenic mice through an arterial cannula showed similar reductions of blood pressure. Intravenous injection of purified RKBP into mice via a catheter produced a dose-dependent reduction of the mean arterial blood pressure. Our findings suggest that RKBP may function as a vasodilator in vivo, independent of regulating the activity of tissue kallikrein.

A study on the induction of differentiation of human leukemic cells by harringtonine combined with cytarabine

Both harringtonine (Harr) and Ara-C are effective for treatment of ANLL. Since it was suggested that Harr could induce leukemic cells to differentiate and Ara-C might be a weak inducer of leukemic cell differentiation, we investigated the effect of Harr in combination with Ara-C on inducing differentiation of leukemic cells. Ten patients with ANLL were treated with low dose Harr in combination with low dose Ara-C. Complete remission was achieved in 8 of the 10 patients. After therapy, severe pancytopenia and moderate myelosuppression occurred in two patients who achieved remission. Four patients demonstrated a decrease in blast cells with an associated transient increase in mature granulocytes during therapy. Auer bodies appeared in 7-8% mature granulocytes in peripheral blood and in bone marrow on the 14th day of combination therapy in one patient. Freshly isolated leukemic cells from six pretreatment patients were cultured in liquid in the presence of Harr in combination with Ara-C. Apparent evidence of differentiation of leukemic cells and Auer bodies in the cytoplasm of mature granulocytic cells were observed in two of the six patients. The above results seem to suggest that the therapeutic effect of low dose Harr plus low dose Ara-C may result from both differentiation induction and cytotoxicity of the leukemic cells.

Autogenous regulation of the regA gene of bacteriophage T4: derepression of translation

The regA gene of phage T4 encodes a translational repressor that inhibits utilization of its own mRNA as well as the translation of a number of other phage-induced mRNAs. In recombinant plasmids, autogenous translational repression limits production of the RegA protein when the cloned structural gene is expressed under control of a strong, plasmid-borne promoter (lambda PL). We have found that a genetic fusion which places the regA ribosome binding domain in proximity to active translation leads to partial derepression of wild-type RegA protein synthesis. The derepression is not due to increased synthesis of regA RNA, suggesting that it occurs at the translational level. Derepressed clones of the wild-type regA gene were used to overproduce and purify the repressor. In an in vitro assay the wild-type target was sensitive and a mutant target was resistant to inhibition by the added protein. The results suggest that the sensitivity of a regA-regulated cistron to translational repression may depend on the competition between ribosomes and RegA protein for overlapping recognition sequences in the translation initiation domain of the mRNA.

[Short term result of lung cancer treated by photodynamic therapy (PDT)]

Fifty four patients with cancer in the lumen of trachea-bronchus proved by histopathology were treated with PDT. 5 mg/kg hematoporphyrin derivative was given. 24-72 hr after injection, PDT was delivered, usually 1-3 times in density of 200-400 J/cm2. There were 69 cancer foci in 54 patients treated by PDT for 168 times in all. One patient, who received the highest number of treatments, was treated for 12 times intermittently. The treatment result: 14 cancer foci gave a complete response, 32 significant response, 21 minor and 2 no responses. Neither hemorrhage nor other serious complications were found. The results suggest that PDT be an effective method for lung cancer. Only being topical in nature, the implication of PDT is expected to be limited.