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Autoantibodies from primary biliary cirrhosis patients with anti-p95c antibodies bind to recombinant p97/VCP and inhibit in vitro nuclear envelope assembly.

We have reported previously that p95c, a novel 95-kDa cytosolic protein, was the target of autoantibodies in sera of patients with autoimmune hepatic diseases. We studied 30 sera that were shown previously to immunoprecipitate a 95 kDa protein from [(35)S]-methionine-labelled HeLa lysates and had a specific precipitin band in immunodiffusion. Thirteen sera were available to test the ability of p95c antibodies to inhibit nuclear envelope assembly in an in vitro assay in which confocal fluorescence microscopy was also used to identify the stages at which nuclear assembly was inhibited. The percentage inhibition of nuclear envelope assembly of the 13 sera ranged from 7% to 99% and nuclear envelope assembly and the swelling of nucleus was inhibited at several stages. The percentage inhibition of nuclear assembly was correlated with the titre of anti-p95c as determined by immunodiffusion. To confirm the identity of this autoantigen, we used a full-length cDNA of the p97/valosin-containing protein (VCP) to produce a radiolabelled recombinant protein that was then used in an immunoprecipitation (IP) assay. Our study demonstrated that 12 of the 13 (93%) human sera with antibodies to p95c immunoprecipitated recombinant p97/VCP. Because p95c and p97 have similar molecular masses and cell localization, and because the majority of sera bind recombinant p97/VCP and anti-p95c antibodies inhibit nuclear assembly, this is compelling evidence that p95c and p97/VCP are identical.

Adenosine Triphosphatases↗

Characterization of a Mycobacterium tuberculosis proteasomal ATPase homologue.

A screen for Mycobacterium tuberculosis (Mtb) mutants sensitive to reactive nitrogen intermediates identified transposon insertions in the presumptive proteasomal ATPase gene mpa (mycobacterium proteasome ATPase; Rv2115c). mpa mutants are attenuated in both wild type and nitric oxide synthase 2 deficient mice. In this work, we show that attenuation of mpa mutants is severe, and that Mpa is an ATPase associated with various cellular activities (AAA) ATPase that forms hexameric rings resembling the eukaryotic complex p97/valosin-containing protein (VCP). Point mutations in the conserved Walker box ATPase motifs of Mpa greatly reduced or abolished ATPase activity in vitro and abrogated protection of Mtb against acidified nitrite. A mutant Mpa protein missing only its last two amino acids retained ATPase activity, yet failed to protect Mtb against nitrite. The corresponding strain was attenuated in mice. Thus, Mpa is an ATPase whose enzymatic activity is necessary but not sufficient to protect against reactive nitrogen intermediates.

Adenosine Triphosphatases↗

Evaluation of intraocular pressure in association with cardiovascular parameters in normocapnic dogs anesthetized with sevoflurane and desflurane.

The objective of this study was to determine intraocular pressure (IOP) and cardiac changes in normocapnic dogs maintained under controlled ventilation and anesthetized using sevoflurane or desflurane. Sixteen healthy adult mixed-breed dogs, seven males and nine females, weighing 10-15 kg were used. The dogs were randomly assigned to one of two groups composed of eight animals anesthetized with sevoflurane (SEVO) or desflurane (DESF). In both groups, anesthesia was induced with propofol (10 mg/kg), and neuromuscular blockade was achieved with rocuronium (0.6 mg/kg/h i.v.). No premedication was given. Ventilation was adjusted to maintain end-tidal carbon dioxide partial pressure at 35 mmHg. Anesthesia was maintained with 1.5 minimum alveolar concentration (MAC) of sevoflurane or desflurane. In both groups IOP was measured by applanation tonometry (Tono-Pen) before induction of anesthesia. IOP, mean arterial pressure (MAP), heart rate (HR), cardiac index (CI) and central venous pressure (CVP) were also measured 45 min after the beginning of inhalant anesthesia and then every 20 min for 60 min. A one-way repeated measures anova was used to compare data within the same group and Student's t-test was used to assess differences between groups. P < 0.05 was considered statistically significant. Measurements showed normal IOP values in both groups, even though IOP increased significantly from baseline during the use of desflurane. IOP did not differ between groups. CI in the desflurane group was significantly greater than in the sevoflurane group. Sevoflurane and desflurane have no clinically significant effects on IOP, MAP, HR, CI or VCP in the dog.

Anesthetics, Inhalation↗

Effects of exercise on neurobehavioral function in community-dwelling older people more than 75 years of age.

OBJECTIVE: We evaluated the effects of exercise on neurobehavioral function in healthy older people more than 75 years of age. DESIGN: A randomized controlled trial with 6-month follow-up was conducted. SETTING: The study was performed in the rural town of Kahoku, Japan, the population of which is considered representative of the older population of Japan. PARTICIPANTS: We studied 42 healthy volunteers (18 men and 24 women; mean age, 79 years (range 75 to 87 years)) who were randomly assigned to one of two groups, exercise or control. INTERVENTION: Subjects assigned to the exercise group were instructed to exercise for 60 minutes twice a week for 6 months. Subjects in the control group were not instructed to engage in an specific exercise regimen. MEASUREMENTS: The following measurements were recorded for both groups at baseline and at 6-month follow-up: (1) Neurobehavioral function as determined by the following tests: Mini-Mental State Exam (MMSE), Hasegawa Dementia Scale Revised (HDSR), Visuospatial Cognitive Performance Test (VCP-test), Button score, Up & Go test, and Functional Reach; and (2) Body mass index and blood pressure. RESULTS: The effects of exercise were shown in the Up & Go test, and Functional Reach (ANOVA with repeated measures). CONCLUSION: This study demonstrates the acceptability and effectiveness of exercise on neurobehavioral function, even in older people more than 75 years of age.

Aged↗

Degradation of tyrosine phosphatase PTPN3 (PTPH1) by association with oncogenic human papillomavirus E6 proteins.

Oncoproteins from DNA tumor viruses associate with critical cellular proteins to regulate cell proliferation, survival, and differentiation. Human papillomavirus (HPV) E6 oncoproteins have been previously shown to associate with a cellular HECT domain ubiquitin ligase termed E6AP (UBE3A). Here we show that the E6-E6AP complex associates with and targets the degradation of the protein tyrosine phosphatase PTPN3 (PTPH1) in vitro and in living cells. PTPN3 is a membrane-associated tyrosine phosphatase with FERM, PDZ, and PTP domains previously implicated in regulating tyrosine phosphorylation of growth factor receptors and p97 VCP (valosin-containing protein, termed Cdc48 in Saccharomyces cerevisiae) and is mutated in a subset of colon cancers. Degradation of PTPN3 by E6 requires E6AP, the proteasome, and an interaction between the carboxy terminus of E6 and the PDZ domain of PTPN3. In transduced keratinocytes, E6 confers reduced growth factor requirements, a function that requires the PDZ ligand of E6 and that can in part be replicated by inhibiting the expression of PTPN3. This report demonstrates the potential of E6 to regulate phosphotyrosine metabolism through the targeted degradation of a tyrosine phosphatase.

Amino Acid Sequence↗

CD4-independent use of Rhesus CCR5 by human immunodeficiency virus Type 2 implicates an electrostatic interaction between the CCR5 N terminus and the gp120 C4 domain.

Envelope glycoproteins (Envs) of human immunodeficiency virus type 2 (HIV-2) are frequently able to use chemokine receptors, CXCR4 or CCR5, in the absence of CD4. However, while these Envs are commonly dual-tropic, no isolate has been described to date that is CD4 independent on both CXCR4 and CCR5. In this report we show that a variant of HIV-2/NIHz, termed HIV-2/vcp, previously shown to utilize CXCR4 without CD4, is also CD4 independent on rhesus (rh) CCR5, but requires CD4 to fuse with human (hu) CCR5. The critical determinant for this effect was an acidic amino acid at position 13 in the CCR5 N terminus, which is an asparagine in huCCR5 and an aspartic acid in rhCCR5. Transferring the huCCR5 N terminus with an N13D substitution to CCR2b or CXCR2 was sufficient to render these heterologous chemokine receptors permissive for CD4-independent fusion. Chimeric Envs between HIV-2/vcp and a CD4-dependent clone of HIV-2/NIHz as well as site-directed Env mutations implicated a positively charged amino acid (lysine or arginine) at position 427 in the C4 region of the HIV-2/vcp env gene product (VCP) gp120 as a key determinant for this phenotype. Because CD4-independent use of CCR5 mapped to a negatively charged amino acid in the CCR5 N terminus and a positively charged amino acid in the gp120 C4 domain, an electrostatic interaction between these residues or domains is likely. Although not required for CD4-dependent fusion, this interaction may serve to increase the binding affinity of Env and CCR5 and/or to facilitate subsequent conformational changes that are required for fusion. Because the structural requirements for chemokine receptor use by HIV are likely to be more stringent in the absence of CD4, CD4-independent viruses should be particularly useful in dissecting molecular events that are critical for viral entry.

Amino Acid Sequence↗

A novel GATA factor transcriptionally represses yolk protein precursor genes in the mosquito Aedes aegypti via interaction with the CtBP corepressor.

In anautogenous mosquitoes, vitellogenesis, the key event in egg maturation, requires a blood meal. Consequently, mosquitoes are vectors of many devastating human diseases. An important adaptation for anautogenicity is the previtellogenic arrest (the state of arrest) preventing the activation of the yolk protein precursor (YPP) genes Vg and VCP prior to blood feeding. A novel GATA factor (AaGATAr) that recognizes GATA binding motifs (WGATAR) in the upstream region of the YPP genes serves as a transcriptional repressor at the state of arrest. Importantly, AaGATAr can override the 20-hydroxyecdysone transactivation of YPP genes, and its transcriptional repression involves the recruitment of CtBP, one of the universal corepressors. AaGATAr transcript is present only in the adult female fat body. Furthermore, in nuclear extracts of previtellogenic fat bodies with transcriptionally repressed YPP genes, there is a GATA binding protein forming a band with mobility similar to that of AaGATAr. The specific repression of YPP genes by AaGATAr in the fat body of the female mosquito during the state of arrest represents an important molecular adaptation for anautogenicity.

Aedes↗

Changes in microvascular fluid filtration capacity during 120 days of 6 degrees head-down tilt.

We used venous congestion strain gauge plethysmography (VCP) to measure the changes in fluid filtration capacity (K(f)), isovolumetric venous pressure (Pv(i)), and blood flow in six volunteers before, on the 118th day (D118) of head-down tilt (HDT), and 2 days after remobilization (Post). We hypothesized that 120 days of HDT cause significant micro- and macrovascular changes. We observed a significant increase in K(f) from 3.6 +/- 0.4 x 10(-3) to 5.7 +/- 0.9 x 10(-3) ml. min(-1). 100 ml(-1). mmHg(-1) (+51.4%; P < 0.003), which returned to pretilt values (4.0 + 0.4 x 10(-3) ml. min(-1). 100 ml(-1). mmHg(-1)) after remobilization. Similarly, Pv(i) increased from 13.4 +/- 2.1 mmHg to 28.9 +/- 2.8 mmHg (+105.8%; P < 0.001) at D118 and was not significantly different at Post (12.4 +/- 2.6 mmHg). Blood flow decreased significantly from 2.3 +/- 0.3 to 1.3 +/- 0.2 ml. min(-1). 100 ml tissue(-1) at D118 and was found elevated to 3.4 +/- 0.7 ml. min(-1). 100 ml tissue(-1) at Post. We believe that the increased K(f) is caused by a higher microvascular water permeability. Because this may result in edema formation, it could contribute to the alterations in fluid homeostasis after exposure to microgravity.

Adult↗

Improving the comparative map of porcine chromosome 10 with respect to human chromosomes 1, 9 and 10.

ZOO-FISH mapping shows human chromosomes 1, 9 and 10 share regions of homology with pig chromosome 10 (SSC10). A more refined comparative map of SSC10 has been developed to help identify positional candidate genes for QTL on SSC10 from human genome sequence. Genes from relevant chromosomal regions of the public human genome sequence were used to BLAST porcine EST databases. Primers were designed from the matching porcine ESTs to assign them to porcine chromosomes using the INRA somatic cell hybrid panel (INRA-SCHP) and the INRA-University of Minnesota Radiation Hybrid Panel (IMpRH). Twenty-eight genes from HSA1, 9 and 10 were physically mapped: fifteen to SSC10 (ACO1, ATP5C1, BMI1, CYB5R1, DCTN3, DNAJA1, EPHX1, GALT, GDI2, HSPC177, OPRS1, NUDT2, PHYH, RGS2, VIM), eleven to SSC1 (ADFP, ALDHIB1, CLTA, CMG1, HARC, PLAA, STOML2, RRP40, TESK1, VCP and VLDLR) and two to SSC4 (ALDH9A1 and TNRC4). Two anonymous markers were also physically mapped to SSC10 (SWR1849 and S0070) to better connect the physical and linkage maps. These assignments have further refined the comparative map between SSC1, 4 and 10 and HSA1, 9 and 10.

Animals↗

Feasibility and efficacy of verbal consents.

Refusal rates for participation in geriatric research have been surprisingly high. This may be due in part to inherent difficulties with a written consent procedure. A simple, easily administered, standardized verbal consent procedure (VCP) for the institutionalized elderly was developed to address this problem. Of 114 patients eligible for enrollment in a study evaluating outcomes of group psychotherapy, 100 gave verbal consent. When written consent was requested, 60 signed immediately; 35, only after substantial coaxing. Five patients refused to sign a consent form, although verbally agreeing to participate. It is estimated that the number of study participants would have been reduced by 40% had written consent been required. The findings raise ethical and logistical issues pertaining to a verbal consent procedure.

Behavioral Research↗

Phenotyping of post-fertilization sperm mitophagy determinants discovered in a mammalian gamete-based cell-free system.

The targeted, substrate-specific degradation of paternal mitochondria inside the zygote, known as post-fertilization sperm mitophagy, is a crucial and evolutionarily conserved early embryonic event. It ensures the exclusive maternal inheritance of the mitochondrial genome. Post-fertilization sperm mitophagy was initially thought to only be achieved via the ubiquitin-proteasome system. Until pro-autophagic receptor proteins such as SQSTM1, GABARAP, as well as the proteasome-interacting ubiquitinated protein dislocase VCP, were identified as contributors to the degradation of the sperm mitochondria early after mammalian fertilization. This synergy of proteasomal and autophagic pathways ensures a timely degradation of sperm mitochondria shortly after fertilization. The discovery of these autophagic receptors lead researchers to believe there might be other autophagic receptors and determinants necessary for proper post-fertilization sperm mitophagy. Based on the established inventory of proteins from mass spectrometry trials of boar spermatozoa exposed to porcine oocyte extracts in an intra-specific porcine cell-free system (CFS), five candidate mitophagy determinants were further investigated in this study, namely LACTB, PRDX3, PSMA8, TOMM34, and FUNDC1. These proteins of interest were studied and validated by using in vitro fertilization (IVF) protocols, cell imaging of spermatids, spermatozoa, oocytes and zygotes, protein interactome analysis, and the porcine CFS. The proteins PSMA8 and TOMM34 behaved in accordance with our proteomic study predictions. The PSMA8 labeling increased after exposure to CFS; in agreement with the classification PSMA8 was given from the mass spectrometry findings. TOMM34 underwent a visible decrease in labeling after exposure to CFS, which also agreed with its proteomic classification; this labeling persisted in IVF zygotes. Except for LACTB, the examined proteins showed mutual interactions as well as interactions with previously identified sperm mitophagy factors in the STRING interactome analysis. Results from this study validate the novel porcine CFS as a valuable tool for the exploration of early fertilization events at a molecular level. Future phenotyping and functional studies using porcine CFS will advance the understanding of mitochondrial inheritance and zygotic development and potentially shed light on the origins of certain mitochondrial diseases arising from the failure of post-fertilization sperm mitophagy.

Animals↗

Intervention strategies and agents mediating the prevention of xenorejection.

Xenotransplantation, the transplantation of cells, tissues, and/or organs across species, has proven to be an enormous challenge, resulting in only limited achievements over the last century. Unlike allotransplantation, the immunologic barriers involved in xenotransplant rejection are aggressive and usually occur within minutes in a hyperacute fashion. The use of organs from phylogenetically related concordant species may not be practical. Discordant xenotransplantation is characterized by hyperacute graft rejection, and to use nonprimate discordant organs for human benefit will require manipulation of the taxonomic differences. The hyperacute rejection process is primarily due to the attachment of preformed xenoreactive antibodies to the donor vascular endothelium, which results in hyperactivation of the complement system beyond the control of the natural complement regulatory proteins. Understanding the complex and diverse immune components involved in hyperacute, acute, and accelerated rejections has resulted in the development of different hematologic and molecular strategies. Plasmapheresis has been used to remove xenoantibodies, and xenoperfusion techniques are used to create a suitable and familiar environment for the xenograft. Various molecular approaches, such as the development of transgenic animals expressing human complement regulatory proteins such as CD59 or decay accelerating factor (DAF), to downregulate complement activation or the production of pigs lacking the xenoreactive antigen by knockout of the Gal alpha-1,3-galactosyl transferase gene have also been attempted. A combination of these techniques together with the administration of soluble complement inhibitors such as the vaccinia virus complement control protein (VCP) may well contribute to prolong graft survival. However, various issues including the possible emergence of new viral infections have confounded the topic of xenotransplantation. Here the different modulatory approaches and agents mediating interventions in xenorejection are discussed.

Acute Disease↗

Filgrastim during combination chemotherapy of patients with poor-prognosis metastatic germ cell malignancy. European Organization for Research and Treatment of Cancer, Genito-Urinary Group, and the Medical Research Council Testicular Cancer Working Party, Cambridge, United Kingdom.

PURPOSE: To determine the effect of r-metHu granulocyte colony-stimulating factor (G-CSF) on the proportion of patients with metastatic poor-prognosis malignant germ cell tumors who receive full dose-intensity combination chemotherapy. PATIENTS AND METHODS: In a phase III study patients received six cycles of BEP/EP (etoposide, and cisplatin, plus or minus bleomycin) or six cycles of BOP/VIP-B (bleomycin, vincristine, cisplatin/etoposide, ifosfamide, cisplatin, bleomycin). A subset were secondarily randomized to receive or not receive filgrastim. Filgrastim 5 microg/kg/day was administered subcutaneously on days 3 through 9 after each BOP and on days 6 through 19 after each VIP, BEP, or EP cycle. RESULTS: Eighty-five percent of 120 eligible patients randomized to filgrastim received at least six chemotherapy cycles compared with 70% of 130 patients randomized to not receive filgrastim (VCP = .003). Patients in the filgrastim-arm achieved significantly higher dose-intensities. Neutropenic fever occurred in 25 of 128 filgrastim-patients and in 38 of 129 non-filgrastim-patients (P = .052). Twelve and three toxic deaths occurred in the non-filgrastim- and filgrastim-arms, respectively. Nine of the 12 toxic deaths and all of the three toxic deaths were associated with febrile grade 4 neutropenia. Failure-free and overall survival were similar in both arms. CONCLUSION: During combination chemotherapy in patients with malignant germ cell tumors, the routine use of filgrastim significantly improved the delivery of the planned treatment schedule without effect on failure-free or overall survival. The use of filgrastim was associated with a clinically important reduction in the number of toxic deaths, confined to the experimental intensified-chemotherapy schedule. This study does not support the routine use of filgrastim during standard chemotherapy with BEP.

Adolescent↗

Characterization of erasin (UBXD2): a new ER protein that promotes ER-associated protein degradation.

Ubiquitin regulator-X (UBX) is a discrete protein domain that binds p97/valosin-containing protein (VCP), a molecular chaperone involved in diverse cell processes, including endoplasmic-reticulum-associated protein degradation (ERAD). Here we characterize a human UBX-containing protein, UBXD2, that is highly conserved in mammals, which we have renamed erasin. Biochemical fractionation, immunofluorescence and electron microscopy, and protease protection experiments suggest that erasin is an integral membrane protein of the endoplasmic reticulum and nuclear envelope with both its N- and C-termini facing the cytoplasm or nucleoplasm. Localization of GFP-tagged deletion derivatives of erasin in HeLa cells revealed that a single 21-amino-acid sequence located near the C-terminus is necessary and sufficient for localization of erasin to the endoplasmic reticulum. Immunoprecipitation and GST-pulldown experiments confirmed that erasin binds p97/VCP via its UBX domain. Additional immunoprecipitation assays indicated that erasin exists in a complex with other p97/VCP-associated factors involved in ERAD. Overexpression of erasin enhanced the degradation of the ERAD substrate CD3delta, whereas siRNA-mediated reduction of erasin expression almost completely blocked ERAD. Erasin protein levels were increased by endoplasmic reticulum stress. Immunohistochemical staining of brain tissue from patients with Alzheimer's disease and control subjects revealed that erasin accumulates preferentially in neurons undergoing neurofibrillary degeneration in Alzheimer's disease. These results suggest that erasin may be involved in ERAD and in Alzheimer's disease.

Adenosine Triphosphatases↗

Osteosarcoma in Paget's disease of bone.

Paget's disease of bone (PDB) is a focal disorder of bone metabolism first described by Sir James Paget in 1876. It is presumed benign in nature and mediated by abnormal osteoclast function. The incidence of osteosarcomas complicating PDB is estimated at <1%. These cancers occur mostly in persons with long-standing, polyostotic disease and affect patients in their seventh decade or when osteosarcoma is remarkably rare in the general population. Epidemiological studies suggest that this late peak of osteosarcomas is absent in regions where Paget's is infrequently reported. Whereas PDB has a predilection for the axial skeleton, skull, femurs, and tibias, pagetic osteosarcoma tend to spare the spine, and are reported more commonly in the pelvis, femur, humerus, and skull. A molecular basis for the association of osteosarcoma with Paget's disease is unclear. These osteosarcomas are osteogenic in origin, consistently arise in sites of pagetic bone, and may present as metachronous, multifocal lesions. On histopathology, the lesions are usually osteoblastic, and the tumor phenotype is sometimes characterized as an exaggerated, chaotic form of the accelerated bone remodeling that characterizes PDB. New insights from the biology of adolescent osteosarcomas, VCP and SQSTM1 mutations now defined in patients with Paget's disease, and emerging evidence that stromal lesions are present in patients with Paget's disease are changing the way we think about the pathogenesis of PDB and the rare complication of pagetic osteosarcomas.

Bone Remodeling↗

[On 23 cases of postinfartual interventricular septal rupture surgically treate. Immediate e long term results (author's transl)].

An experimental study on myocardial viability after acute occlusion of the left anterior descending coronary artery (LAD) for period of six hours is described. For this study 24 adult dogs were used in which an acute myocardial infarction for an area of 20-30% of left ventricul were obtained with ligatures completely occluding the LAD and his collaterals. Following ligature release, on the LAD only, ECG, BP, VCP and histology were studied with the general clinical conditions. The Authors affirm that clinical and ECGraphic data became worse after reperfusion; instead histological data show the possibility of recovery of many muscolar cells of ischemic and neighbouring areas.

Animals↗

Elevation of serum riboflavin carrier protein in breast cancer.

Presently available tumor markers have had a limited clinical impact. Riboflavin carrier protein (RCP) is an estrogen inducible protein that occupies a key position in riboflavin metabolism. Because other vitamin carrier proteins (VCP) have been shown to be overexpressed in patients with malignant disease, we evaluated serum RCP levels in patients with adenocarcinoma of the breast. In this prospective blinded study, patients with breast cancer, benign breast disease, and healthy controls were analyzed for RCP levels. Using a highly sensitive RIA, we observed that serum RCP levels were significantly elevated in women with breast cancer (n = 52) as compared with control subjects [n = 50; 6.06 +/- 7.27 ng/ml versus 0.70 +/- 0.19 ng/ml (mean +/- SD), respectively; P < 0.0001]. A serum RCP level of > or = 1.0 ng/ml was highly predictive of the presence of breast cancer, detecting 88% of tumors in stages I-II and 100% of tumors in stages III-IV. Overall, this RCP assay has a sensitivity of 92.3%, a specificity of 88%, a positive predictive value of 88.9%, and a negative predictive value of 91.7%. These results show increased serum levels of RCP in breast adenocarcinoma patients and suggest that RCP levels may be useful as a new marker for breast cancer. The positive predictive value in early-stage breast cancer suggests that the RCP assay may be a useful adjunct to present screening technology.

Adenocarcinoma↗

A synergistic increase of apoptosis utilizing Fas antigen expression induced by low doses of anticancer drug.

Anticancer drugs have been known to enhance both Fas receptor and Fas ligand expression on tumor cells. Recently, low doses of cytosine arabinoside (ara-C) were reported to enhance Fas antigen expression in the human myeloid leukemia cell line HL60. Here, we showed that low doses of ara-C (LD-ara-C) and etoposide (LD-VP-16) but not vincristine (LD-VCR) induce Fas expression in the human monocytic leukemia cell line U937. We determined the concentrations of ara-C, VP-16 and VCR as 10, 100 and 1 ng/ml, respectively. The ratios for Fas antigen expression induced in non-treated U937 by 24 h incubations with ara-C, VP-16 or VCR were 1.90, 1.36 and 1.00, respectively. Utilizing the Fas antigen expression induced by low doses of anticancer drugs, we examined whether anti-Fas IgM monoclonal antibody (CH-11) combined with LD-ara-C, LD-VP-16 or LD-VCR enhances apoptosis. When CH-11 and LD-anticancer drug were added simultaneously, the ratios of annexin V positive cells were 67.8 +/- 2.4% with ara-C, 70.0 +/- 1.6% with VP-16 and 54.2 +/- 1.3% with VCR. Thus, the ratios of annexin V positive cells significantly increased when CH-11 was simultaneously added to the cells with ara-C (p < 0.0001) and VP-16 (p < 0.0001), but not with VCP (p = 0.5559), compared with the sums of annexin V positive ratios of CH-11 and LD-anticancer drug added separately. We examined whether a broad-range caspase inhibitor (C.I.) can inhibit the Fas expression enhanced by LD-anticancer drugs. However, the Fas expression enhanced by LD-ara-C or LD-VP-16 was not inhibited by a broad-range caspase inhibitor. We demonstrated that apoptosis induced by LD-ara-C or LD-VP-16 is synergistically increased by the addition of CH-11 in U937.

Antibodies, Monoclonal↗