Applying recommended definition of aggressive prostate cancer: a validation study using high-quality data from the Cancer Registry of Norway.

BACKGROUND: The Prostate Cancer Cohort Consortium (PC3) Working Group proposed a definition for aggressive prostate cancer (PC) for aetiologic epidemiologic research. We aimed to validate this definition as well as a second approach utilising only information on stage at diagnosis. METHODS: First primary PCs diagnosed 2004 - 2009 in the population-based Janus Serum Bank (JSB) cohort were identified by linkage to the population-based Cancer Registry of Norway (CRN) (n = 3568). The CRN and Norwegian Prostate Cancer Registry provided clinicopathological data for these cases. Approach 1 classified PC as aggressive if it was clinically T4, or N1, or M1, or had a Gleason score ≥8 at diagnosis (as proposed). Approach 2 classified PC as aggressive if CRN stage at diagnosis was 'regional spread' or 'distant metastases'. Both approaches were validated by calculating the sensitivity and positive predictive value (PPV) against PC-death within 10 years of diagnosis. RESULTS: Overall, 555 died from PC within 10 years. Approach 1 classified 24.7% of cases as aggressive and 13.6% were unclassified due to missing information. Approach 2 classified 19.6% as aggressive and 29% were unclassified. Sensitivity was highest for Approach 1 (0.76, 95% CI: 0.72 - 0.80 vs 0.69, 95% CI: 0.64 - 0.73), while PPVs were similar for both approaches (0.43, 95% CI: 0.40 - 0.46 and 0.40, 95% CI: 0.36 - 0.44). We observed similarly high sensitivity and higher PPVs than those reported by the PC3 Working Group. CONCLUSIONS: The proposed definition of aggressive PC was applicable and valid in the JSB cohort. Stage at diagnosis can be useful if data on cTNM or Gleason score is unavailable.

Expression of myeloperoxidase in acute myeloid leukemia blasts mirrors the distinct DNA methylation pattern involving the downregulation of DNA methyltransferase DNMT3B.

Myeloperoxidase (MPO) has been associated with both a myeloid lineage commitment and favorable prognosis in patients with acute myeloid leukemia (AML). DNA methyltransferase inhibitors (decitabine and zeburaline) induced MPO gene promoter demethylation and MPO gene transcription in AML cells with low MPO activity. Therefore, MPO gene transcription was directly and indirectly regulated by DNA methylation. A DNA methylation microarray subsequently revealed a distinct methylation pattern in 33 genes, including DNA methyltransferase 3 beta (DNMT3B), in CD34-positive cells obtained from AML patients with a high percentage of MPO-positive blasts. Based on the inverse relationship between the methylation status of DNMT3B and MPO, we found an inverse relationship between DNMT3B and MPO transcription levels in CD34-positive AML cells (P=0.0283). In addition, a distinct methylation pattern was observed in five genes related to myeloid differentiation or therapeutic sensitivity in CD34-positive cells from AML patients with a high percentage of MPO-positive blasts. Taken together, the results of the present study indicate that MPO may serve as an informative marker for identifying a distinct and crucial DNA methylation profile in CD34-positive AML cells.

Sporadic isolations of a multi-drug resistant Pseudomonas aeruginosa clone during a 14-month epidemic in a general hospital in Hiroshima.

BACKGROUND: During 2005-2007, we experienced sporadic isolations of multidrug-resistant (MDRP) Pseudomonas aeruginosa from wards in a general hospital in Hiroshima. The objective of this study was to analyze epidemiology relationships and the mode of spread of the strains. METHODS: Clonality was assessed using pulsed-field gel electrophoresis (PFGE) and serotyping. MICs were determined using the microdilution broth method. Investigations of the affected patients' movements and environmental sampling from the affected wards were conducted. RESULTS: An abrupt increase in MDRP isolations began at the end of 2005 and ended in February 2007. A total of 25 MDRP strains were sporadically isolated from nine wards. Fourteen strains were genotypically and serologically identical. Analysis of the patients' movements identified that six of the 14 MDRP-positive patients became positive for MDRP when they were in the intensive care unit (ICU), and two became positive after the patients moved from the ICU to another nursing unit. Four MDRP strains were isolated from patients who did not stay in the ICU and were in ward E6, which had the second highest number of isolations. In July 2006, environmental sampling of the hospital identified a toilet brush in ward E6 that was contaminated with MDRP that was genotypically and serologically identical to the clinical isolates. CONCLUSIONS: Our study suggests that the sporadic increase in MDRP isolates during 2005-2007 in the general hospital in Hiroshima was due to an epidemic of an MDRP clone. Continuity and spread of infection was probably due to cross infection and contamination in the hospital with the MDRP strain.

Topical application of Aggregatibacter actinomycetemcomitans cytolethal distending toxin induces cell cycle arrest in the rat gingival epithelium in vivo.

BACKGROUND: Aggregatibacter actinomycetemcomitans is one of the etiological pathogens implicated in the onset of periodontal disease. This pathogen produces cytolethal distending toxin (CDT) that acts as a genotoxin to induce cell cycle arrest and cellular distension in cultured cell lines. Therefore, CDT is a possible virulence factor; however, the in vivo activity of CDT on periodontal tissue has not been explored. Here, CDT was topically applied into the rat molar gingival sulcus; and the periodontal tissue was histologically and immunohistochemically examined. MATERIALS AND METHODS: Recombinant purified A. actinomycetemcomitans CDT was applied to gingival sulcus of male Wistar rats and tissue samples were immunohistochemmically examined. RESULTS: One day after application, infiltration of neutrophils and dilation of blood vessels in the gingival connective tissue were found. At day three, desquamation and detachment of cells in the junctional epithelium was observed. This abrasion of junctional epithelium was not observed in rats treated with mutated CDT, in which a His274Ala mutation is present in the CdtB subunit. This indicates the tissue abrasion may be caused by the genotoxicity of CdtB. Expression of the proliferating cell nuclear antigen (PCNA), a marker for proliferating cells, was significantly suppressed using CDT treatment in the junctional epithelium and gingival epithelium. CONCLUSION: Using the rat model, these data suggest CDT intoxication induces cell cycle arrest and damage in periodontal epithelial cells in vivo.

LBH589, a deacetylase inhibitor, induces apoptosis in adult T-cell leukemia/lymphoma cells via activation of a novel RAIDD-caspase-2 pathway.

Adult T-cell leukemia/lymphoma (ATLL), an aggressive neoplasm etiologically associated with human T-lymphotropic virus type-1 (HTLV-1), is resistant to treatment. In this study, we examined the effects of a new inhibitor of deacetylase enzymes, LBH589, on ATLL cells. LBH589 effectively induced apoptosis in ATLL-related cell lines and primary ATLL cells and reduced the size of tumors inoculated in SCID mice. Analyses, including with a DNA microarray, revealed that neither death receptors nor p53 pathways contributed to the apoptosis. Instead, LBH589 activated an intrinsic pathway through the activation of caspase-2. Furthermore, small interfering RNA experiments targeting caspase-2, caspase-9, RAIDD, p53-induced protein with a death domain (PIDD) and RIPK1 (RIP) indicated that activation of RAIDD is crucial and an event initiating this pathway. In addition, LBH589 caused a marked decrease in levels of factors involved in ATLL cell proliferation and invasion such as CCR4, IL-2R and HTLV-1 HBZ-SI, a spliced form of the HTLV-1 basic zipper factor HBZ. In conclusion, we showed that LBH589 is a strong inducer of apoptosis in ATLL cells and uncovered a novel apoptotic pathway initiated by activation of RAIDD.

Clonal distribution of enterotoxigenic Staphylococcus aureus on handles of handheld shopping baskets in supermarkets.

AIMS: Shopping carts and handheld shopping baskets in supermarkets are subject to accidental bacterial contamination through contacts with a variety of food. We investigated the prevalence of Staphylococcus aureus on the handles of handheld shopping baskets in four supermarkets distantly located in Osaka district, Japan. METHODS AND RESULTS: Fifty two strains of Staph. aureus were isolated from 760 basket handles. Among these, six strains were positive for staphylococcal enterotoxin B (SEB) production, representing 12% of total. This SEB producer ratio is considerably higher than among Staph. aureus isolated from nasal swabs of the supermarket workers (2%) and from independently collected clinical specimens (4%). These SEB-producing Staph. aureus strains from the basket handles are clonal and belong to ST12. Coagulase typing showed that they are in group VII, which is the most common cause of food poisoning in Japan. Biofilm assays indicated that SEB gene (seb)-positive strains including this clone produced a significantly higher amount of biofilm than seb-negative strains. CONCLUSIONS: The frequent isolation of seb-positive Staph. aureus on shopping basket handles raises the possibility that they could be a hidden reservoir for Staph. aureus with a potential to cause food poisoning and draws attention to the importance of shopping basket sanitation.

All-optical flip-flop operation based on asymmetric active-multimode interferometer bi-stable laser diodes.

We demonstrate fast and low energy all optical flip-flop devices based on asymmetric active-multimode interferometer using high-mesa waveguide structure. The implemented devices showed high speed all-optical flip-flop operation with 25 ps long pulses. The rising and falling times of the output signal were 121 ps and 25 ps, respectively. The required set and reset pulse energies were only 7.1 fJ and 3.4 fJ, respectively.

Activation of p53 by Nutlin-3a, an antagonist of MDM2, induces apoptosis and cellular senescence in adult T-cell leukemia cells.

It has been reported that the induction of cellular senescence through p53 activation is an effective strategy in tumor regression. Unfortunately, however, tumors including adult T-cell leukemia/lymphoma (ATL) have disadvantages such as p53 mutations and a lack of p16(INK4a) and/or p14(ARF). In this study we characterized Nutlin-3a-induced cell death in 16 leukemia/lymphoma cell lines. Eight cell lines, including six ATL-related cell lines, had wild-type p53 and Nutlin-3a-activated p53, and the cell lines underwent apoptosis or cell-cycle arrest, whereas eight cell lines with mutated p53 were resistant. Interestingly, senescence-associated-beta-galactosidase (SA-beta-gal) staining revealed that only ATL-related cell lines with wild-type p53 showed cellular senescence, although they lack both p16(INK4a) and p14(ARF). These results indicate that cellular senescence is an important event in p53-dependent cell death in ATL cells and is inducible without p16(INK4a) and p14(ARF). Furthermore, knockdown of Tp53-induced glycolysis and apoptosis regulator (TIGAR), a novel target gene of p53, by small interfering RNA(siRNA) indicated its important role in the induction of cellular senescence. As many patients with ATL carry wild-type p53, our study suggests that p53 activation by Nutlin-3a is a promising strategy in ATL. We also found synergism with a combination of Nutlin-3a and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), suggesting the application of Nutlin-3a-based therapy to be broader than expected.

Detection of a single bacterial cell using a 16S ribosomal RNA-specific oligonucleotide probe designed to investigate periodontal pathogens.

INTRODUCTION: The current detection methods for periodontopathogens mainly use polymerase chain reactions. However, there are few methods available for visualizing the bacteria that impact on patients with periodontal disease for use in health education. The purpose of this study was to develop a specific detection method to visualize periodontopathogenic bacteria. METHODS: Fluorescently-labeled oligonucleotide probes directed to specific 16S ribosomal RNA (rRNA) sequences of Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans were synthesized. Cultured individual bacterial species were fixed with 4% paraformaldehyde and smeared on glass slides. Fluorescein isothiocyanate-labeled oligonucleotide probes were hybridized under stringent conditions with smeared whole cells, and then probe specificity was investigated by epifluorescence microscopy. RESULTS: Comparatively long (50-mer) oligonucleotide probes for P. gingivalis and A. actinomycetemcomitans were designed. These probes clearly hybridized with 16S rRNA of the target species in situ and single bacterial cells were detectable visually. The probes exhibited no cross-hybridization against the additional organisms that were closely related to the target species. CONCLUSIONS: The fluorescence in situ hybridization technique is a specific and reliable method by which to visually identify the target organisms. The oligonucleotide probes designed in this study will be useful for detecting P. gingivalis and A. actinomycetemcomitans populations.

Serum cytochrome c to indicate the extent of ongoing tumor cell death.

Despite the significant implication of apoptosis in tumorigenesis, there is no biomarker to assess the extent of ongoing apoptosis in vivo for hematological malignancies. We investigated the potential of serum cytochrome c (cyto-c) as a biomarker for apoptosis. Cyto-c and lactate dehydrogenase (LD) were released into the culture medium from apoptotic cells induced by tumor necrosis factor-related apoptosis-inducing ligand in a time-dependent manner in vitro, with different kinetic patterns. Only one-third of 153 patients with hematological malignancies showed high levels of serum cyto-c (>20 ng/ml). Although serum cyto-c level was roughly correlated to serum LD activity, their different kinetic patterns from serial measurements indicated that serum cyto-c rather than LD is a more sensitive indicator for tracking changes of tumor status. Furthermore, serum cyto-c level stratified patients with acute adult T-cell leukemia into favorable and unfavorable subgroups with 5-year survival rates of 67%vs. 11%. In conclusion, serum cyto-c may provide a fast real-time biomarker for tracking changes of tumor status involved in apoptotic cell death, but lacking disease or cell-type specificity.

Rapid and high-resolution detection of IgH gene rearrangements using PCR and melting curve analysis.

The analytical methods of Southern blot hybridization (SBH) and the polymerase chain reaction (PCR) for complementarity determining region-3 (CDR3) are fundamental for detecting IgH gene rearrangement. However, there are problems stemming from the characteristics of both methods; especially, the long turn around time (TAT) because of the complex process in the SBH, and the low analytical sensitivity for amplicons in the PCR. Thus, to improve the PCR procedure, we investigated the application of detecting the clonal amplicons based on the different melting Temperature (T(m)) in internal melting domains corresponding to the CDR3 hypervariable region. Our new protocol is based on the combination of a LightCycler Technology with high-speed amplification, and Idaho-Technology with rapid and high-resolution melting curve analysis (MCA), designated PCR-MCA. This method can provide the results within 3 h with an analytical sensitivity of 10(-3). The diagnostic sensitivity and specificity relative to the results documented with the SBH analysis were 89.2% and 100%, respectively. This indicates that the new protocol of PCR-MCA is acceptable for clinical testing; especially, PCR-MCA is relevant in terms of the rapid and sensitive detection of IgH clonality within amplicons.

Proviral status of HTLV-1 integrated into the host genomic DNA of adult T-cell leukemia cells.

Human T-cell leukemia virus type-1 (HTLV-1) is the etiological agent of adult T-cell leukemia (ATL), and leukemic cells always carry the proviral genome monoclonally integrated into their host genomes at the same sequence site, designated as the monoclonal integration. Using Southern blot hybridization (SBH) and sequenced tagged site polymerase chain reaction assays, we examined the proviral status in 558 clinical specimens from 350 patients who are suspected to have ATL. A total of 321 specimens (57.5%) from 241 patients showed positive results for the monoclonal integration according to SBH, using EcoR1 and Pst1. The 241 patients consisted of 136 patients (56.4%) with the complete provirus (C-type), 62 patients (25.7%) with a defective provirus (D-type), and 43 patients (17.8%) with multibands (M-type). The incidence of the D- and M-types were in the order of smoldering, chronic, and acute subtypes of ATL, suggesting that such an aberrant proviral status is generated on the way to multistep carcinogenesis and is subsequently clinically important for the malignant behavior of the disease. Moreover, our data showed that the partial deletion of the proviral genome is initiated first at the site of the gag region and spreads into the sites of the pol and env regions, whereas the long terminal repeats and pX regions are almost always conserved. These results suggest that analysis of the proviral status provides useful diagnostic and virologic-oncological information about ATL and HTLV-1 pathology, especially the important role of pX gene in tumorigenesis.

Sensitivity of adult T-cell leukaemia lymphoma cells to tumour necrosis factor-related apoptosis-inducing ligand.

Tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) induces apoptosis in many transformed cells, but not in normal cells, and hence TRAIL has recently emerged as a novel anti-cancer agent. Adult T-cell leukaemia lymphoma (ATLL) is a neoplasm of T-lymphocyte origin aetiologically associated with human T-lymphotropic virus type 1 (HTLV-I), and is resistant to standard anti-cancer therapy. We thus characterized the sensitivity of ATLL cells to TRAIL in this study. Although most primary ATLL cells and cell lines expressed TRAIL death receptors on their surface, they showed only restricted sensitivity to TRAIL. Among the 10 ATLL cell lines examined, one was sensitive, but two had insufficient death-receptor expression, two had an unknown resistant mechanism with abrogation of the death signal upstream of caspase-8, and the remaining five showed attenuation of the signal in both extrinsic and intrinsic pathways by X-linked inhibitor of apoptosis and Bcl-2/Bcl-xL respectively. Furthermore, the level of HTLV-I tax expression was significantly correlated to TRAIL resistance. Interestingly, ATLL cells themselves expressed TRAIL on the cell surface. Constitutive production of TRAIL may offer resistance, thus allowing the development of TRAIL-resistant ATLL cells. Consequently, the resistant mechanism in ATLL cells against TRAIL was assigned to multiple factors and was not explained by a definitive single agent.

Simultaneous expression of guinea pig UDP-glucuronosyltransferase 2B21 and 2B22 in COS-7 cells enhances UDP-glucuronosyltransferase 2B21-catalyzed morphine-6-glucuronide formation.

Although UDP-glucuronosyltransferases (UGTs) act as an important detoxification system for many endogenous and exogenous compounds, they are also involved in the metabolic activation of morphine to form morphine-6-glucuronide (M-6-G). The cDNAs encoding guinea pig liver UGT2B21 and UGT2B22, which are intimately involved in M-6-G formation, have been cloned and characterized. Although some evidence suggests that UGTs may function as oligomers, it is not known whether hetero-oligomer formation leads to differences in substrate specificity. In this work, evidence for a functional hetero-oligomer between UGT2B21 and UGT2B22 is provided by studies on the glucuronidation of morphine in transfected COS-7 cells. Cells transfected with UGT2B21 cDNA catalyzed mainly morphine-3-glucuronide formation although M-6-G was also formed to some extent. In contrast, cells transfected with UGT2B22 cDNA did not show any significant activity toward morphine. When UGT2B21 and UGT2B22 were expressed simultaneously in different ratios in COS-7 cells, extensive M-6-G formation was observed. This stimulation of M-6-G formation was not observed, however, when microsomes containing UGT2B21were mixed with those containing UGT2B22 in the presence of detergent. Furthermore, this effect was not very marked when human UGT1A1 and UGT2B21 were coexpressed in COS-7 cells. This is the first report suggesting that UGT hetero-oligomer formation leads to altered substrate specificity.

Actinobacillus actinomycetemcomitans induces lethal effects on the macrophage-like human cell line U937.

We examined the cytotoxicity in culture medium of Actinobacillus actinomycetemcomitans against the human monocyte-macrophage-like cell line U937 using the trypan blue exclusion test and WST-1 test. We found that A. actinomycetemcomitans Y4 showed the highest cytotoxic activity among the three different serotype strains and the cytotoxic effects of both bacterial cells and culture supernatants in A. actinomycetemcomitans Y4 were stronger on phorbol-12-myristate 13-acetate (PMA)-induced U937 cells than uninduced U937 cells. Morphological changes in PMA-induced U937 cells treated with culture supernatants differed from those treated with leukotoxin, and a difference in the susceptibility to 56 degrees C heat treatment was found between culture supernatants and leukotoxin. The cytotoxic activity by WST-1 was determined more rapidly and strongly than that by trypan blue assay. These findings suggested that the cytotoxic effect of A. actinomycetemcomitans was influenced by the differentiation of U937 cells and may be more potent on the respiratory chain than the cell membrane.

Toxicity and toxin profiles of the newt, Cynops pyrrhogaster from western Japan.

A total of 382 specimens of a Japanese newt, Cynops pyrrhogaster, were collected from western Japan during 1996 to 1999, and assayed for their individual, geographical, sexual, seasonal variations, and anatomical distribution of toxicity by mouse. Most of the specimens tested showed toxicity scores ranging from 5 to 370 MU/g, where no seasonal, but large individual, sexual, and regional variations of toxicity were clearly recognized. Among the parts, skin and muscle showed higher toxicity scores (56 MU/g) than liver, stomach, intestine and gonad, whose toxicity ranged from less than 2 to 33 MU/g. The C. pyrrhogaster toxin was purified by several steps of column chromatography and was shown to consist of tetrodotoxin (TTX) and 6-epiTTX as main components, and 4-epiTTX, 4,9-anhydro-6-epiTTX, and 4,9-anhydroTTX as minor ones by means of HPLC and 1H-NMR analyses.

Occurrence of tetrodotoxin in the skin of a rhacophoridid frog Polypedates sp. from Bangladesh.

Twenty-three specimens of a tree-frog Polypedates sp. were collected from two locations (Mymensingh and Barisal) of Bangladesh in 1999, and assayed for their toxicity scores and toxin principle. Among the tissues, only the skin of the Mymensingh specimens was found to be toxic in mouse test, with the toxicity scores of 31-923MU/g. The toxin isolated from the skin was analyzed by high-performance liquid chromatography, electrospray ionization-time of flight mass spectrometry and proton nuclear magnetic resonance, and characterized as tetrodotoxin, a toxin principle.

Antibacterial effect of silver-zeolite on oral bacteria under anaerobic conditions.

OBJECTIVES: The purpose of this study was to evaluate the antibacterial effect of silver-zeolite (SZ) against oral bacteria under anaerobic conditions. METHODS: The antibacterial activity of SZ was evaluated by determining the minimum inhibitory concentrations (MICs) using two-fold serial dilutions of SZ in Brain Heart Infusion broth. Release of Ag+ into the broth was measured by an atomic absorption technique. RESULTS: SZ inhibited the growth of the bacteria tested under anaerobic conditions. The MIC of SZ ranged between 256 and 2048 micrograms/ml, which corresponded to a range of 4.8-38.4 micrograms/ml of Ag+. All strains grew in broth containing 16,384 micrograms/ml of type-A zeolite. SIGNIFICANCE: These results suggested that SZ may be a useful vehicle to provide antibacterial activity to dental materials used even under anaerobic conditions such as deep in the periodontal pocket.

Lactacystin activates FLICE (caspase 8) protease and induces apoptosis in Fas-resistant adult T-cell leukemia cell lines.

Lactacystin (LC) is a specific inhibitor of the proteasome, and has recently been shown to induce apoptosis in certain cell lines. In the present study, we established Fas-resistant adult T-cell leukemia (ATL) cell subclones RSO4 and RST1 from their parental Fas-sensitive cell lines SO4 and ST1, and examined whether LC can overcome Fas resistance. LC completely inhibited proteasome function as determined by a peptidyl-MCA substrate (LLVY-MCA and LLE-MCA), and induced apoptosis in these cell lines irrespective of Fas sensitivity at low concentrations (approximately 10 microM). LC induced the activation of caspase 3 (CPP32/Yama) and caspase 6 proteases in an identical manner to Fas-mediated apoptosis. Moreover, LC induced the activation of caspase 8 (FLICE) protease, which is the initiator of the Fas-mediated apoptotic cascade. Synthesized proteasome inhibitory peptide MG-115 (ZLLnV-CHO) also induced apoptosis in these cell lines. These results indicated that proteasome inhibitors overcome Fas-resistance by bypassing the proximal part of the Fas signal. Inhibition of the proteasome function may be a new strategy for the treatment of ATL.

Qualitative and quantitative characterization of Fas (CD95) expression and its role in primary human acute leukemia cells.

Fas antigen, a cell surface molecule, directly mediates apoptosis, and is expressed on a limited number of human tissues. Blood or bone marrow samples from patients with acute myelogenous leukemia (AML), acute lymphoblastic leukemia (ALL) and mixed leukemia were examined qualitatively and quantitatively for the expression of Fas as well as its function using flow cytometry and the annexin V staining method. Fas expression was flow cytometrically unimodal with heterogeneous density, and showed quantitatively characteristic features in different diseases: undetectable in mixed leukemia, faint to weak in ALL, low in M0 and M1, and variable (low to strong) in M2, M3, M4, and M5. Both the full-length and the alternatively spliced truncated mRNAs were detected constitutively even in acute leukemia cells with qualitatively negative and quantitatively faint Fas, and the band density of the former transcripts detected by RT-PCR was correlated with the level of expression of the Fas protein. Short-term culturing of freshly isolated leukemia cells gave rise to an increase of Fas density. In acute leukemia cells, the apoptosis induced by anti-Fas MoAb was compared with that induced by etoposide (a topoisomerase II inhibitor). We found that fresh ALL and AML cells were resistant to the anti-Fas IgM antibody, while etoposide could trigger apoptosis in all types of leukemia tested. The combined effects of the anti-Fas MoAb and etoposide were not always synergistic. These results suggest that Fas is a biological marker for characterizing ALL and AML cells, and provide insight into creating a new therapeutic modality using cytotoxic drugs and cytokines together with modulation of Fas.