Abstract IA-22: Cellular responses to telomerase perturbations

Telomerase is a ribonucleoprotein that replenishes the DNA at telomeres, thereby counteracting telomere shortening. Telomerase is highly active in many human malignancies. Telomerase functions in cancer maintenance include replenishing telomeric DNA and maintaining cell immortality. The telomerase RNA component provides a short template that is copied to make telomeric DNA. We found that mutating the template to cause various aberrant telomeric sequences to be added in human cancer cells rapidly caused massive ATM-dependent and ATM-independent chromosome fusions and cell death.

We also showed previously that human cancer cells responded rapidly to abrupt depletion of telomerase RNA by rapid and distinctive cellular/transcriptional responses, despite no obvious bulk telomere shortening or loss of telomere integrity. This and evidence from others indicates that, in addition to its telomere-elongating role, telomerase may play other roles in cells: cells lacking or overexpressing telomerase show a variety of responses even in the absence of detectable effects on telomere integrity or functionality. We are performing ChIP—SEQ experiments to identify genomic sites of telomerase interaction. New results of experiments exploring these roles of telomerase in cancer will be presented. Together, these and other findings indicate that telomerase, both via its roles in telomere maintenance and other roles, provides potential new inroads into cancer therapies.

Citation Information: Cancer Res 2009;69(23 Suppl):IA-22.

Ulinastatin suppresses systemic inflammatory response following lung ischemia-reperfusion injury in rats

OBJECTIVE

We sought to investigate whether ulinastatin (urinary trypsin inhibitor) inhibited systemic inflammatory responses following lung ischemia-reperfusion (I/R) injury.

MATERIALS AND METHODS

Establishing a steady left lung warm I/R model in rats, we randomly divided 32 animals into 4 groups: sham (n = 8); I/R (n = 8); low-dose ulinastatin (5000 U/kg pre-ischemia) + I/R (n = 8); and high-dose ulinastatin (10,000 U/kg pre-ischemia) + I/R (n = 8). Measured variables included plasma concentrations of tumor necrosis factor-alpha (TNF-alpha), as well as interleukin (IL)-6 and IL-8.

RESULTS

The serum concentrations of TNF-alpha, IL-6, and IL-8 in the ulinastatin pretreated groups were markedly decreased compared with those of the I/R group (P < .05). The levels of TNF-alpha, IL-6, and IL-8 were lower in the high-dose ulinastatin group compared with the low-dose ulinastatin group (P < .05).

CONCLUSION

Ulinastatin produced dose-dependent attenuation of the systemic inflammatory response of rats following lung I/R injury.

Selective albumin exchange: a novel and simple method to remove bilirubin

PURPOSE

Owing to its non-selectivity, plasma exchange has limited use in the treatment of patients with hepatic failure, although it is effective in removal of protein-bound toxins. This study reports a novel way to perform selective albumin exchange (SAE) by using a secondary plasma separator and aims to study its depurative capacity in the removal of bilirubin.

METHOD

In ex vivo experiments, the sieving coefficients (SCs) of plasma proteins for two secondary plasma separators, EC20W and EC30W (Asahi Medical, Tokyo, Japan), were measured. The EC20W membrane was chosen for use in clinical treatment because of its higher selectivity in separating albumin from plasma than the EC30W. The SCs of albumin, immunoglobumin G, A and M (IgG, IgA, IgM) for the EC20W were 0.3+/-0.021, 0.017+/-0.012, and 0, respectively. Five inpatients with plasma total bilirubin (TB) more than 200 micromol/L were enrolled in the present study and received a total of 10 SAE therapy sessions. Each session lasted 10 hours. SAE using the EC20W was conducted, making it similar to post-dilution continuous veno-venous hemofiltration (CVVH), with a filtrate rate of 2000 ml/h. Replacement fluid was composed by adding human albumin into conventional CVVH replacement fluid, with a final albumin concentration of 0.6%. During each treatment, the parameters of plasma and filtrate TB, direct bilirubin (DB), indirect bilirubin (IDB), and proteins were dynamically monitored. Hemostasis parameters were measured before and after sessions.

RESULTS

The reduction ratio of plasma TB, DB, and IDB after a single session was 29.1+/-3.0%, 31.3+/-4.5%, and 18.7+/-10.2%, respectively. The clearance of TB at initiation was 11.1+/-1.3 mL/min and declined to 4.4+/-0.5 ml/min at the end (p<0.01). This decline was accompanied by a reduction in albumin SC from 0.3+/-0.021 to 0.13+/-0.05. The molar ratio of bilirubin to albumin in filtrate was comparable to that in plasma. After a single treatment, plasma protein concentration including total protein, albumin, IgA and IgM remained unaffected, except for globulin and IgG, which were reduced by 11.5+/-7.8% and 11.1+/-2.3%, respectively. An improvement in hemostasis parameters, including plasma fibrinogen, prothrombase time and INR, was found after treatment. No obvious side effects were reported during any of the sessions.

CONCLUSION

Selective albumin exchange is a simple and effective method to remove bilirubin. However, further studies are required to verify its effects on clinical outcome.

Population pharmacokinetics of mycophenolic acid in senile Chinese kidney transplant recipients

To explore the pharmacokinetic characteristics of mycophenolic acid (MPA) among elderly Chinese kidney transplant recipients, we enrolled 24 patients over 60 years old (65.6 +/- 3.6) as the (Gs) group and 24 patients of 39.6 +/- 14.3 years old as a control group (Ga). Venous blood samples were taken at 0 (predose), 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, and 12 hours after the morning dose of mycophenolate mofetil at 10 to 12 weeks posttransplant. Plasma MPA concentrations were measured by a validated high-performance liquid chromatography method. Within 6-month posttransplant follow-up, there had not been an acute rejection episode when five elderly and one other adult experienced severe adverse events (SAEs), such as pneumonia and leukocytopenia. MPA area under the curve (AUC) in Gs was significantly lower than that among Ga (P < .05), while there was no significant difference in predose, peak concentrations, or peak times (P > .05). The concentration-time curve of Gs showed a bipeak pattern in five patients (20.8%) during the early stage (2 to 4 hours postdose). AUC in the subgroup of Gs with SAEs (n = 5) was significantly higher than that of elderly subjects without SAEs (n = 19) (P = .042). When Gs were subdivided at a cutting AUC point of 25 mug/mL, the SAE incidence was significantly higher in the subgroup with a higher AUC than than those with the lower AUC (P = .047). Through multiple stepwise regression, we obtained a minimal model to estimate MPA AUC of elderly recipients: AUC = 3.0410 + 9.8588 x C(0) + 0.5963 x C(0.5) + 2.5612 x C(3) (R(2) = .893).

Long-term correction of diabetes in rats after lentiviral hepatic insulin gene therapy

AIMS/HYPOTHESIS

Type 1 diabetes results from the autoimmune destruction of pancreatic beta cells. Exogenous insulin therapy cannot achieve precise physiological control of blood glucose concentrations, and debilitating complications develop. Lentiviral vectors are promising tools for liver-directed gene therapy. However, to date, transduction rates in vivo remain low in hepatocytes, without the induction of cell cycling. We investigated long-term transgene expression in quiescent hepatocytes in vitro and determined whether the lentiviral delivery of furin-cleavable insulin to the liver could reverse diabetes in rats.

MATERIALS AND METHODS

To improve transduction efficiency in vitro, we optimised hepatocyte isolation and maintenance protocols and, using an improved surgical delivery method, delivered furin-cleavable insulin alone or empty vector to the livers of streptozotocin-induced diabetic rats by means of a lentiviral vector. Rats were monitored for changes in body weight and blood glucose, and intravenous glucose tolerance tests were performed. Expression of insulin was determined by RT-PCR, immunohistochemistry and electron microscopy.

RESULTS

We achieved long-term transgene expression in quiescent hepatocytes in vitro (87 +/- 1.2% transduction efficiency), with up to 60 +/- 3.2% transduction in vivo. We normalised blood glucose for 500 days-a significantly longer period than previously reported-making this the first successful study using a lentiviral vector. This procedure resulted in the expression of genes encoding several beta cell transcription factors, some pancreatic endocrine transdifferentiation, hepatic insulin storage in granules, and restoration of glucose tolerance. Liver function tests remained normal. Importantly, pancreatic exocrine transdifferentiation did not occur.

CONCLUSIONS/INTERPRETATION

Our data suggest that this regimen may ultimately be employed for the treatment of type 1 diabetes.

Interferon regulatory factor-1-induced apoptosis mediated by a ligand-independent fas-associated death domain pathway in breast cancer cells

Interferon (IFN) regulatory factor-1 (IRF-1) is a transcription factor that has apoptotic anti-tumor activity. In breast cancer cell types, IRF-1 is implicated in mediating apoptosis by both novel and established anti-tumor agents, including the anti-estrogens tamoxifen and faslodex. Here we demonstrate that in MDA468 breast cancer cells, apoptosis by IFN-gamma is mediated by IRF-1 and IFN-gamma, and IRF-1-induced apoptosis is caspase-mediated. IRF-1 induction results in cleavage of caspase-8, -3 and -7, and application of caspase inhibitors attenuate activated cleavage products. IRF-1-induced apoptosis involves caspase-8 since apoptosis is significantly decreased by the caspase-8-specific inhibitor IETD, c-FLIP expression and in caspase-8-deficient cancer cells. Furthermore, we demonstrate that IRF-1-induced apoptosis requires fas-associated death domain (FADD) since dominant-negative FADD expressing cells resist IRF-1-induced apoptosis and activated downstream products. Immunofluorescent studies demonstrate perinuclear colocalization of FADD and caspase-8. Despite the known role of FADD in mediating death-ligand induced apoptosis, neutralizing antibodies against classical death receptors do not inhibit IRF-1 induced apoptosis, and no secreted ligand appears to be involved since MDA468 coincubated with IRF-1 transfected cells do not apoptose. Therefore, we demonstrate that IRF-1 induces a ligand-independent FADD/caspase-8-mediated apoptosis in breast cancer cells.

Ulinastatin attenuates lung ischemia-reperfusion injury in rats by inhibiting tumor necrosis factor alpha

Ischemia-reperfusion (I/R) injury may influence graft function following transplantation. Ulinastatin, a urinary trypsin inhibitor has been shown to attenuate I/R injury in various organs such as intestine, heart, and kidney in animals. The present experiment was designed to evaluate the effect of pretreatment with ulinastatin on I/R-induced lung injury.

METHODS

After establishing a constant left lung warm ischemia-reperfusion model in rats, 45 animals were randomly divided into three experimental groups: sham group (n = 15), IR group (n = 15), and ulinastatin (5000 U/kg pre-ischemia) + IR group (n = 15). The lung injury was evaluated by tissue myeloperoxidase activity, with simultaneous estimation of the serum concentration of TNFalpha.

RESULTS

The ulinastatin-pretreated animals exhibited markedly decreased lung tissue myeloperoxidase activity (P < .05). Blood gas analysis demonstrated, that the treated animals had significantly ameliorated pulmonary oxygenation (P < .05). The serum concentration of TNF-alpha in the ulinastatin-pretreated group was markedly decreased compared with that of the I/R group (P < .05).

CONCLUSIONS

Ulinastatin attenuated I/R-induced lung injury. This function is partly related to the capacity of the agent to inhibit myeloperoxidase activity in lung tissue and decrease systemic expression to TNF-alpha.

The gateway to transcription: identifying, characterizing and understanding promoters in the eukaryotic genome

Eukaryotic transcriptional regulation requires the integration of complex signals by the transcriptional promoter. Distinct sequence elements, characteristic chromatin modifications and coordinated protein-DNA interactions at these sequences constitute a transcriptional regulatory code that remains poorly understood today. Here, we review recent experimental and computational advances that have enabled the identification and analysis of transcriptional promoters on an unprecedented scale, laying a foundation for systematic determination of the transcriptional regulatory networks in eukaryotic cells. The knowledge gained from these large-scale investigations has challenged some conventional concepts of promoter structure and function, and provided valuable insights into the complex gene regulatory mechanisms in a variety of organisms.

Influence of hydroxyethyl starch 130/0.4 in pulmonary neutrophil recruitment and acute lung injury during polymicrobial sepsis in rats

BACKGROUND

Acute lung injury (ALI) is a progressive syndrome associated with significant mortality in sepsis patients. Neutrophils are key cells in the inflammatory response that characterizes ALI. This study was designed to explore the effects of hydroxyethyl starch (HES) 130/0.4 (a novel plasma substitute) on pulmonary neutrophil recruitment and associated ALI in a rat sepsis model induced by cecal ligation and puncture (CLP).

METHODS

Animals were randomly assigned to six groups [saline control; CLP and saline; CLP and HES (7.5, 15 and 30 ml/kg); and HES control], subjected to CLP and infused with or without HES 130/0.4 4 h after CLP. Six hours later, the pulmonary capillary permeability (PCP), myeloperoxidase (MPO) activity, lung histological changes, tumor necrosis factor-alpha, interleukin-1beta and cytokine-induced neutrophil chemoattractant levels, P-selectin mRNA expression and nuclear factor-kappa B (NF-kappaB) activation were measured.

RESULTS

Resuscitation with HES 130/0.4 significantly attenuated the CLP-induced increase in PCP, MPO activity, cytokine/chemokine levels, mRNA expression of P-selectin and NF-kappaB activation, all of which are involved in the recruitment of neutrophils. Groups receiving the higher doses of HES 130/0.4 (15 and 30 ml/kg) were more adequately resuscitated.

CONCLUSION

HES 130/0.4 can inhibit CLP-induced neutrophil recruitment and subsequent ALI by attenuating cytokines/chemokines, adhesion molecule-mediated inflammation and NF-kappaB activation.

MCM7 amplification and overexpression are associated with prostate cancer progression

The genomic DNA profiles of prostate cancers with aggressive features were compared to the profiles of matched normal DNA to identify genes that are selectively amplified in the cancer cells. One of the identified genes, MCM7, which is a component of the DNA replication licensing complex, has been studied extensively both at the DNA and protein levels in human prostate tissues. Approximately half of the prostate cancer specimens studied showed MCM7 gene amplification, and 60% of the aggressive prostate cancer specimens had increased MCM7 protein expression. Amplification or overexpression of MCM7 was significantly associated with relapse, local invasion and a worse tumor grade. Constitutive expression of MCM7 in a human prostate cancer cell line, DU145, resulted in markedly increased DNA synthesis and cell proliferation compared to vector-only controls, and an increased cell invasion in vitro. Indeed, MCM7 overexpression produced primary tumors 12 times larger than vector-only controls and resulted in a rapid demise of mice bearing those tumors. These studies implicate MCM7, and the DNA replication licensing gene family, in prostate cancer progression, growth and invasion.

Crystallization and preliminary X-ray diffraction analysis of glutathione peroxidase from human plasma

The extracellular form of glutathione peroxidase from human plasma has been crystallized by the sitting-drop vapour-diffusion method. The crystals belong to tetragonal space group I4(1) with cell dimensions of a = b = 83.1 and c = 131.0 A. They diffract beyond 2.9 A resolution and have one dimer in the asymmetric unit. A self-rotation function analysis shows the possible (222) symmetry for the tetramers of this enzyme.

Could X-ray microbeams inhibit angioplasty-induced restenosis in the rat carotid artery?

BACKGROUND

Parallel, thin (<100 microm) planes of synchrotron-generated X rays, have been shown to spare normal tissues and preferentially damage tumors in animal models. The aim of the present study was to assess the effect of such microbeams directed unidirectionally on angioplasted rat carotid arteries.

METHODS AND MATERIALS

Three groups of Sprague-Dawley rats were studied: (a) rats with normal, untreated arteries, (b) rats treated by balloon angioplasty, but not irradiated, and (c) rats treated with balloon angioplasty and exposed to single fraction, unidirectional, parallel, microbeams an hour after angioplasty. The microbeam array, 15 mm widex7.6 mm high, consisting of 27-microm-wide beam slices, spaced 200 microm center-to-center laterally traversed the damaged artery. The in-depth in-beam dose was 150 Gy, the "valley" dose (dose midway between microbeams resulting mainly from X-ray scattering) was 4.5 Gy on average, and the "integrated" (averaged) dose was 26 Gy.

RESULTS

Microbeam irradiation, as given in the present study, was tolerated, but was insufficient to significantly suppress the neointimal hyperplasia.

DISCUSSION

The microbeam dose used is considered low. Dose escalation would be necessary to reach conclusive results regarding the X-ray microbeam efficacy to control restenosis.

cDNA cloning and high-level expression of a thrombin-like enzyme from Agkistrodon acutus venom

Agkistrodon acutus (Guenther), a poisonous snake species of the family of Crotalidae, is mainly found south of the Yellow River in China. The main symptom of this poison is massive hemorrhage, in which thrombin-like enzymes (TLEs) in the venom play an important role. TLEs are abundant, especially in the venom of A. acutus. We isolated the total RNA from the venom gland tissue of A. acutus and amplified the cDNAs of the TLEs using reverse transcription-polymerase chain reaction (RT-PCR). The cDNAs were cloned into vector pThioHis B and were expressed as fusion proteins in the form of inclusion bodies, which accounted for nearly 50% of the total cell proteins. The inclusion bodies were washed, dissolved, refolded and purified by affinity chromatography. The purity was higher than 97%, as indicated by capillary zone electrophoresis. The renatured recombinant enzyme exhibited arginine esterase activity, as tested by the BAEE method, and also showed a fibrinogen cleavage effect, as detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). This method provides a fast and convenient system for studying the structure-function relationships in TLE isoenzymes, and also a practical way for mass production of TLEs in the pharmaceutical industry.

The antiangiogenic and therapeutic implications of endostatin

Angiogenesis plays a vital role in the pathology of cancer, ischemic diseases and chronic inflammation, among other conditions. Endostatin, a newly found protein that is distributed in some parts of the human body, has been demonstrated to have a strong inhibitory role in angiogenesis. It specifically inhibits the proliferation of endothelial cells and induces their apoptosis both in vitro and in vivo. Preclinical research has proven its effective role in the treatment of various experimental tumors in rodents. Although endostatin therapy has entered phase II clinical trials in the USA, the exact mechanism and its effects on antiangiogenesis, especially the action on the suppression of endothelial cell proliferation and induction of apoptosis, remain unclear. The treatment modality for malignancies and other angiogenesis-related diseases still requires further analysis.

Recombinant human endostatin is beneficial to endothelial cell growth exposed to mildly oxidized low-density lipoproteins

Endostatin significantly reduced atherosclerosis in genetically susceptible mice. One of the main factors associated with atherogenesis is oxidized low-density lipoproteins (LDL), which also causes apoptosis of endothelial cells. Therefore, we proposed that the antiatherogenic effect of endostatin was partly associated with its protective effect on the endothelial injury induced by oxidized LDL. To confirm such a hypothesis, we studied the effects of recombinant human endostatin (rhEndo) on the proliferation of cultured endothelial cells exposed to mildly oxidized LDL (mox-LDL), rhEndo did not show an obvious inhibitory effect on the proliferation of rabbit aorta endothelial cells (RAEC) (p > 0.05), while mox-LDL inhibited their proliferation (p < 0.01 or p < 0.05). Interestingly, rhEndo seemed to antagonize the role of mox-LDL in inhibiting the proliferation of RAEC. rhEndo seemed, thus, to be beneficial to the proliferating endothelial cells, suggesting that it protects RAECs from the injury caused by mox-LDL. The activity of rhEndo in endothelial cells may possibly result from the interaction of different factors in cell signaling, which remains to be further elucidated.

Preliminary research on myosin light chain kinase in rabbit liver

AIM: To study preliminarily the properties of myosin light chain kinase (MLCK) in rabbit liver.

METHODS: The expression of MLCK was detected by reverse transcription-polymerase chain reaction (RT-PCR); the MLCK was obtained from rabbit liver, and its activity was analyzed by γ-³² P incorporation technique to detect the phosphorylation of myosin light chain.

RESULTS: MLCK was expressed in rabbit liver, and the activity of the enzyme was similar to rabbit smooth muscle MLCK, and calmodulin- dependent. When the concentration was 0.65 mg •L¯¹, the activity was at the highest level.

CONCLUSION: MLCK expressed in rabbit liver may catalyze the phosphorylation of myosin light chain, which may play important roles in the regulation of hepatic cell functions.

Producing parallel x rays with a bent-crystal monochromator and an x-ray tube

A bent Laue monochromator and a conventional x-ray tube were used to produce a fan beam that was parallel in the plane perpendicular to the plane of the fan. The x-ray fan beam was tunable in energy and had about 12% energy bandwidth at a slice height of 5 mm when tuned to 50 keV. The beam's energy was slightly coupled to the vertical position on the beam's height. The slice height could be varied from 1 to 10 mm. The flux at 50 keV was approximately 2x10(6) photons/mm2/s with a rotating anode tungsten x-ray tube operating at 120 kVp and 100 mA. The narrow energy bandwidth of the beam produced is advantageous over a conventional divergent polychromatic beam for all radiography applications, while the parallelism of the beam enhances its intensity by about threefold and offers some advantages for computed tomography.