Flow cytometric detection of the mitochondrial BCL-2 protein in normal and neoplastic human lymphoid cells

Myrtle (Myrtus communis) leaf extract suppresses hepatotoxicity induced by monosodium glutamate and acrylamide through obstructing apoptosis, DNA fragmentation, and cell cycle arrest

A large number of plant extracts have demonstrated to provide health benefits and mitigate several disease conditions. However, at the molecular and cellular levels, few studies have been conducted. The present work was designed to study the effect of Myrtus communis leaf extract (ME) (300 mg/kg bw) against hepatotoxicity induced by monosodium glutamate (MSG) (100 mg/kg bw), and acrylamide (ACR) (20 mg/kg bw) in male rats and determining its molecular and cellular mechanisms. The data showed that the treatment with MSG and/or ACR induced significant changes in numerous biomarkers (Bcl-2 and the programmed cell death protein-1) related to liver damage, as recorded by genotoxicity, apoptosis, and histopathological changes. On the other side, the oral administration of ME (300 mg/kg bw) improved the hepatic conditions as confirmed by the improvement in cell viability, programmed cell death, and histopathological alterations. It can be concluded that the consumption of ME might be useful for minimizing the occurred hepatotoxicity through up-regulation of the key apoptotic regulators as well as the improvement of DNA content and cell cycle restoration. Graphical abstract.

Marjoram and sage oils protect against testicular apoptosis, suppressed Ki-67 expression and cell cycle arrest as a therapy for male infertility in the obese rats

Alterations in testicular apoptosis, cell cycle progression and proliferation rate in dietary-induced obese male rats and role of oral administration of marjoram (0.16 ml/kg BW) and sage (0.05 ml/kg BW) oils were evaluated. Results showed increased body weight, serum leptin, testicular lipid peroxidation, protein oxidation and nitric oxide, with reduction in serum testosterone, sperm count and endogenous enzymatic and non-enzymatic antioxidants in testis of the obese rats. Flow cytometry results revealed increased number of annexin-V (+ve) cells with activation of apoptotic proteins (Bax, caspase-3) and reduction of anti-apoptotic Bcl-2. Cell cycle arrest at phases S and G2/M with decline in expression of Bcl-2 and germ cell proliferation marker ki-67 was also validated, indicating lowered spermatogenesis in the obese rats. Supplementation of marjoram or sage oils displayed normalized body weight, sperm count, germ cells apoptosis and proliferation, suggesting the two oils as a new therapeutic approach against obesity promoted male infertility. PRACTICAL APPLICATIONS: Obese men have a greater chance of fertility problems compared to those with normal weight. Obesity-associated oxidative stress and free radicals production have shown to adversely affect sperm quality with activation of pro-apoptotic pathways, allowing germ cell death. Marjoram and sage essential oils are now being widely studied due to their antioxidant and radical scavenging properties. Our findings indicated effectiveness of the two oils for combating body weight gain, testicular oxidative stress, and apoptosis, which seemed to aid in increasing sperm count. The outcomes of this study may help scientists to formulate novel medications for improving fertility problems in men.

Radiosensitizing effect of ellagic acid on growth of Hepatocellular carcinoma cells: an in vitro study

Failure of treatment for cancer in clinic by radio/chemotherapy is generally attributed to tumour resistance. Therefore, it is important to develop strategies to increase the cytotoxicity of tumour cells by radiation in combination with unique tumour selective cytotoxic agents. We evaluated the potential of ellagic acid (EA) as an enhancer of oxidative stress in cancer cells. HepG2 cells were treated with EA (10 µM) for 12 h prior to exposure of single 7.5 Gy dose of irradiation. Treatment of HepG2 cells with EA and gamma radiation showed increased reactive oxygen species generation, up regulation of p53 protein expression, decreased survival markers level like p-Akt, p-NF-kB and p-STAT3 which were significantly higher after radiation treatment alone. We also found that combination treatment increased G2/M phase cell population, decreased IL-6, COX–2 and TNF-α expression and caused a loss in mitochondrial membrane potential with decreased level of angiogenesis marker MMP-9. Over expression of Bax and activation of caspase 3 indicated the apoptosis of the cells. The results provided a strong unique strategy to kill cancer cells HepG2, using less radiation dose along with effective pro-oxidant dose of EA.

Ferulic acid (FA) abrogates γ-radiation induced oxidative stress and DNA damage by up-regulating nuclear translocation of Nrf2 and activation of NHEJ pathway

The present study was aimed to evaluate the radioprotective effect of ferulic acid (FA), a naturally occurring plant flavonoid in terms of DNA damage and damage related alterations of repair pathways by gamma radiation. FA was administered at a dose of 50 mg/kg body weight for five consecutive days prior to exposing the swiss albino mice to a single dose of 10 Gy gamma radiation. Ionising radiation induces oxidative damage manifested by decreased expression of Cu, Zn-SOD (SOD stands for super oxide dismutase), Mn-SOD and catalase. Gamma radiation promulgated reactive oxygen species (ROS) mediated DNA damage and modified repair pathways. ROS enhanced nuclear translocation of p53, activated ATM (ataxia telangiectasia-mutated protein), increased expression of GADD45a (growth arrest and DNA-damage-inducible protein) gene and inactivated Non homologous end joining (NHEJ) repair pathway. The comet formation in irradiated mice peripheral blood mononuclear cells (PBMC) reiterated the DNA damage in IR exposed groups. FA pretreatment significantly prevented the comet formation and regulated the nuclear translocation of p53, inhibited ATM activation and expression of GADD45a gene. FA promoted the nuclear translocation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and activated NHEJ repair pathway to overcome ROS mediated oxidative stress and DNA damage. Therefore, the current study stated that FA can challenge the oxidative stress by (i) inducing nuclear translocation of Nrf2, (ii) scavenging ROS, and (iii) activating NHEJ DNA repair process.

Herbicide exposure induces apoptosis, inflammation, immune modulation and suppression of cell survival mechanism in murine model

The present study demonstrates paraquat induced cellular toxicity in spleen and associated ROS generation, mitochondria dependent cellular apoptosis, inflammation and splenomegaly inSwiss Albinomice.

Melatonin controlled apoptosis and protected the testes and sperm quality against bisphenol A-induced oxidative toxicity

Epidemiological reports have indicated a correlation between the increasing bisphenol A (BPA) levels in the environment and the incidence of male infertility. In this study, the protective effects of melatonin on BPA-induced oxidative stress and apoptosis were investigated in the rat testes and epididymal sperm. Melatonin (10 mg/kg body weight (bw)) was injected concurrently with BPA (50 mg/kg bw) for 3 and 6 weeks. The administration of BPA significantly increased oxidative stress in the testes and epididymal sperm. This was associated with a decrease in the serum testosterone level as well as sperm quality, chromatin condensation/de-condensation level, and the percentage of haploid germ cells in the semen. BPA administration caused a significant increase in apoptosis accompanied by a decrease in the expression of the antiapoptotic proteins Bcl-2 in the testes and epididymal sperm. The concurrent administration of melatonin decreased oxidative stress by modulating the levels of glutathione, superoxide dismutase, and catalase as well as the malondialdehyde and hydrogen peroxide concentrations in the testes and sperm. Melatonin sustained Bcl-2 expression and controlled apoptosis. Furthermore, melatonin maintained the testosterone levels, ameliorated histopathological changes, increased the percentages of seminal haploid germ cells, and protected sperm chromatin condensation process, indicating appropriate spermatogenesis with production of functional sperm. In conclusion, melatonin protected against BPA-induced apoptosis by controlling Bcl-2 expression and ameliorating oxidative stress in the testes and sperm. Thus, melatonin is a promising pharmacological agent for preventing the potential reproductive toxicity of BPA following occupational or environmental exposures.

Smokeless tobacco consumption impedes metabolic, cellular, apoptotic and systemic stress pattern: A study on Government employees in Kolkata, India

Smokeless tobacco (SLT) remains a threat amongst a large population across the globe and particularly in India. The oral use of tobacco has been implicated to cause physiological stress leading to extreme toxicological challenge. The study included 47 SLT-users and 44 non-users providing a spectrum of pathophysiological, clinico-biochemical, antioxidant parameters, cell cycle progression study of PBMC and morphological changes of red blood cells (RBC). The expressions of p53, p21, Bax, Bcl-2, IL-6, TNF- α, Cox-2, iNOS were analyzed from thirteen representative SLT-users and twelve non-users. Difference in CRP, random glucose, serum cholesterol, TG, HLDL-C, LDL-C, VLDL-C, neutrophil count, monocyte count, ESR, SOD (PBMC) and TBARS (RBC membrane) were found to be statistically significant (p < 0.05) between the studied groups. The current study confers crucial insight into SLT mediated effects on systemic toxicity and stress. This has challenged the metabolic condition leading to a rise in the inflammatory status, increased apoptosis and RBC membrane damage. The above findings were substantiated with metabolic, clinical and biochemical parameters. This is possibly the first ever in-depth report and remains an invaluable document on the fatal effects of SLT.

Expression of apoptotic markers BCL-2 and Bax in chronic hepatitis C virus patients

OBJECTIVES

Hepatitis C viral infection(HCV) influence the susceptibility to apoptosis. This could lead to insufficient antiviral immune response and persistent viral infection.

DESIGN AND METHODS

Group 1: chronic HCV patients with liver cirrhosis and ascites. Group 2: chronic HCV patients without liver cirrhosis and group 3: healthy subjects as control group. Bcl-2 and Bax expression were evaluated by flowcytometry.

RESULTS

HCV patients (with cirrhosis and ascites) had a statistically significantly low Bcl-2 expression, a significantly high Bax expression and a significantly decreased Bcl-2/Bax ratio compared with controls. While, the results are inverted in the other HCV group. Both groups of HCV, Bcl-2/Bax ratio showed a significant positive correlation with Bcl-2 and a significantly negative correlation with Bax.

CONCLUSIONS

Chronic HCV exhibit a deregulation of apoptosis with the disease progression. This provides an insight into the pathogenesis of chronic HCV infection, and may contribute to the therapy.

BH3-only proteins: the death-puppeteer's wires

Most cell death in vertebrates proceeds through the intrinsic pathway of apoptosis and results from unregulated increase of mitochondrial membrane permeability. Bcl2-associated X protein (Bax) and Bcl2-antagonist/killer protein (Bak), the effector proapoptotic members of the Bcl-2 family, are, in their active state, the principal accomplices for this permeabilization process. How exactly Bax and Bak are activated has been a matter of major investigation in the last decade, and suitable tools offered by quantitative cytometric methodologies have significantly contributed to the understanding of the function of Bcl-2 family members. Here, we review the most relevant findings in this field and highlight one common trait that has emerged from the diverse new theories: a crucial role in the control of Bax/Bak activation has to be attributed to the BH3-only subset of the Bcl-2 family. BH3-only proteins exert their proapoptotic activity by hierarchical and tightly tuned interactions with other Bcl-2 family members and operate as sensors of intracellular/extracellular death signals and vectors of information to the core apoptotic machinery. Given their essential role in apoptosis, BH3-only molecules are proposed as molecular targets for the cure of diseases associated with abnormal cell death, as in the case with neurodegenerative conditions. As well, they are explored as possible tools for cancer therapy, according to the concept that molecules mimicking the BH3 domain of these proteins could selectively and efficiently cooperate in the cell killing by chemotherapeutic drugs. A few BH3 mimetics are currently being tested in clinical trials of hematologic and solid tumors. Nevertheless, the knowledge about the cellular and molecular mechanisms that regulate responsiveness to BH3 therapy has to be further expanded and will benefit from recent advances in cytometric quantitative technologies.

Preparation of cells and reagents for flow cytometry

Flow cytometry is widely used for analyzing the expression of cell surface and intracellular molecules (on a per cell basis), characterizing and defining different cell types in heterogeneous populations, assessing the purity of isolated subpopulations, and analyzing cell size and volume. This technique is predominantly used to measure fluorescence intensity produced by fluorescent-labeled antibodies or ligands that bind to specific cell-associated molecules. A procedure for direct and indirect staining of single-cell suspensions of lymphoid tissue or peripheral blood lymphocytes to detect cell surface membrane antigens is presented. In addition, support protocols present methods for fluorescence labeling of purified antibodies. A protocol for flow cytometric analysis of intracellular antigens in single-cell suspensions is also included. Alternate protocols describe intracellular staining of unfixed cells in the presence of a detergent and staining of nonviable cells to facilitate discrimination of dead cells in fixed or permeabilized cell preparations.

Solamargine induces apoptosis and sensitizes breast cancer cells to cisplatin

Solamargine (SM), a major steroidal alkaloid glycoside, was purified from Solanum incanum plant. SM exhibited the most cytotoxic effect comparing with that of cisplatin (cDDP), methotrexate (MTX), 5-fluorouracil (5-FU), epirubicin (EPI) and cyclophosphamide (CP) against human breast cancer cells. In this study, SM induces apoptosis of the breast cancer cells and the mechanism was characterized. SM up-regulated the expressions of external death receptors, such as tumor necrosis factor receptor I (TNFR-I), Fas receptor (Fas), TNFR-I-associated death domain (TRADD), and Fas-associated death domain (FADD). SM also enhanced the intrinsic ratio of Bax to Bcl-2 by up-regulating Bax and down-regulating Bcl-2 and Bcl-xL expressions. These effects resulted in the release of mitochondrial cytochrome c and activation of caspase-8, -9 and -3 in the cells, indicating that SM triggered extrinsic and intrinsic apoptotic pathways of breast cancer cells. Similar to function way of SM, cDDP causes cancer cell apoptosis though caspase-8/caspase-3 and Bax/cytochrome c pathways, but the resistance to cDDP is correlated with Bcl-2 and Bcl-xL overexpression. However, the overexpression of Bcl-2 and Bcl-xL can be broken through by SM. The combined treatment of SM and cDDP significantly reduced Bcl-2 and Bcl-xL expressions, and enhanced Bax, cytochrome c, caspase-9 and -3 expressions in breast cancer cells. Thus, the combined use of SM and cDDP may be effective in cDDP-resistant breast cancer.

Directing DNA methylation to inhibit gene expression

: 1. DNA methylation is a critical epigenetic modification that silences gene transcription, participates in X-chromosome inactivation in females, and regulates genomic imprinting. 2. We have devised a method to inhibit transcriptional initiation by constructing short methylated oligonucleotides which induce DNA methylation at specific loci. 3. The methodology by which we devise these oligonucleotides is described, using oligonucleotides directed against the oncogene, Bcl-2.4. The human Bcl-2 gene contains two promoters, each of which contains a CpG island in its core region. Oligonucleotides are designed which can inhibit Bcl-2 transcription and lead to decreased mRNA and protein in vitro. When compared to standard anti-sense oligonucleotide action, these methylated oligonucleotides are far more sensitive and potentially, longer acting. 5. In principle, using this methodology, it should be possible to design methylated oligonucleotides that can methylate CpG islands and thereby downregulate any gene.

Idiotypic T cells specific for Morbillivirus nucleocapsid protein process and present their TCR to cognate anti-idiotypic CD8+ T cells

CD8(+) T cells are activated by the presentation of antigenic peptide through MHC class I molecules. Newly synthesized proteins formed as defective ribosomal products (DRiPs) can act as a major source of antigenic peptides for MHC class I presentation pathway. Majority of these peptides are generated from the intracellular degradation of self antigens. In the present study, we have shown that newly synthesized T cell receptor (TCR) beta chains formed as DRiPs in T cells are ubiquitinated and degraded by the proteasomes. These TCR-DRiPs are processed and presented by activated T cells to cognate anti-idiotypic CD8(+) T cells. Presentation of TCR idiopeptide (peptide derived from the variable region of idiotypic TCR) by activated T cells leads to Bcl-2 expression and cytokine secretion by anti-idiotypic CD8(+) T cells. Presentation of intracellular antigen by T cells may have important implications in immunoregulation, control of lymphotropic virus infection and autoimmune diseases.

Bcl-2 protein and DNA ploidy in renal cell carcinoma: do they affect patient prognosis?

AIM

The aim of the present study was to correlate bcl-2 protein expression and DNA-ploidy status with established prognostic parameters in renal cell carcinoma (RCC) and to examine their impact on disease progression and patient survival.

METHODS

Both parameters were prospectively measured in 50 consecutive radical nephrectomy specimens using flow cytometry. They were correlated with the tumor grade, stage and histological type. Kaplan-Meier survival analysis for all parameters was performed.

RESULTS

Bcl-2 protein expression was higher in RCC compared to normal renal tissue (P < 0.0001). Aneuploid tumors had higher bcl-2 expression compared to diploid tumors (P = 0.015). Bcl-2 expression and DNA content were not correlated with tumor histological types (P = 0.277/P = 0.419), grades (P = 0.690/P = 0.449), T categories (P = 0.637/P = 0.585) or stages (P = 0.726/P = 0.800). Median follow-up time was 46 months (range, 5-84) with a mean overall survival of 61.8 months (95% confidence interval, 53.7-69.9). Tumor stage was the only statistically important prognostic factor (P = 0.0045).

CONCLUSION

Although Bcl-2 expression was correlated with tumor DNA content, the prognostic value of these two parameters following radical nephrectomy was not established.

Immunosuppression by Morphine-Induced Lymphocyte Apoptosis: Is It a Real Issue?

Morphine has been an optimal choice for cancer pain management. However, several recent studies suggested that morphine induces apoptosis in human peripheral blood lymphocytes (PBLs), raising a serious concern about the use of opioid-based analgesic strategies. In this study, therefore, we aimed to evaluate whether morphine induced apoptosis in cultured human PBLs. Apoptotic events were assessed by flow-cytometrical detection of surface phosphatidylserine and nuclear fragmentation, as well as Fas, Bcl-2, and Caspase-3 activity in PBLs gated on a light-scatter basis. Peripheral blood mononuclear cells isolated from healthy subjects were cultured with etoposide, morphine, or vehicle (medium) for 48 h. During co-culture with etoposide, apo-ptosis was significantly induced in PBLs, and the cells did not survive for 48 h. In comparison, morphine had no effect on the expression rate of any of the detected molecules, suggesting that no apparent apoptotic processes were induced during the incubation. Furthermore, co-incubation with a Fas-specific antibody did not increase apoptotic cell rates in the morphine cultures. These results do not support the hypothesis that morphine directly modulates PBL apoptosis resulting in immunosuppression. We believe that the choice of opioids for optimal pain relief should not be discouraged until further studies clarify this issue.

IMPLICATIONS

Recent reports that morphine potentially induces apoptosis in human lymphocytes in vitro have raised a concern about the use of opioid-based analgesic strategies. Regarding this issue, we present rather contradictory findings that morphine has no effects on the cell expression of various apoptosis-related molecules in cultured human lymphocytes.

Inverse relationship between the ratio of ICAM-1 expressing lymphocytes and serum TGF-β1 concentrations in acute rheumatic fever

Autoimmunity in acute rheumatic fever (ARF) is triggered by group-A beta hemolytic streptococci (GAS). Although most of the recent work has focused on the major impact of lymphocytes, the exact immunopathogenesis is still unresolved. Regulation of self-tolerance in response to GAS has been investigated in various animal experiments. This study aimed to associate the ratio of lymphocytes bearing adhesion/costimulatory molecules, Bcl-2/CD95 and serum TGF-beta1 concentrations with clinical stages of ARF. Thirty-five patients were assigned according to the clinical stages. Bcl-2 expression on CD19+ and CD3+ lymphocytes was similar within patient groups and controls. CD62p expression was higher in patients with carditis. The ratio of ICAM-1 bearing lymphocytes was significantly different between patient groups and controls and was increased through acute to remission stages longitudinally. In contrast, a gradual and significant decrease in TGF-beta1 concentrations was observed longitudinally from acute to chronic stages. A positive correlation has been documented between ICAM-1+ lymphocyte ratios and Fas+ cytotoxic T cell ratios supported by a prominent increase in CD95+ T cells. These data draw our attention to the role of ICAM-1, Fas and TGF-beta1 in ARF pathogenesis through the perspective of self-tolerance in a clinical setting.

Patensin-induced apoptosis is accompanied by decreased bcl-2 expression and telomerase activity in HL-60 cells

The present study aimed to investigate the effect of telomerase activity in patensin-induced apoptosis and the regulation of B cell leukemia/lymphoma 2 (bcl-2) gene expression in human leukemia HL-60 cells. Apoptosis of HL-60 cells was induced by patensin (100 micromol L(-1)) for 3, 6, 12 and 24 h. Apoptosis and bcl-2 were determined by flow cytometry analysis. A polymerase-chain-reaction-based telomeric repeat amplification protocol assay was used to detect the telomerase activity. Patensin induced growth arrest and apoptotic cell death in HL-60 cells. The telomerase activity was inhibited in a time-dependent manner during the patensin-induced apoptosis of HL-60 cells, and the expression of bcl-2 was progressively down-regulated by patensin. Inhibition of the telomerase activity of HL-60 cells was closely related to the patensin-induced apoptosis. The present results indicate that inhibition in telomerase and reduced bcl-2 gene expression may play a role in the patensin-induced apoptosis of HL-60 cells.

Mcl-1 and Bcl-2/Bax ratio are associated with treatment response but not with Rai stage in B-cell chronic lymphocytic leukemia

Although both Bcl-2/Bax ratio and Mcl-1 have been identified to be of clinical relevance in B-cell chronic lymphocytic leukemia (CLL), there is controversy regarding their role; further, their relative importance is not well delineated. Expression of Bcl-2, Bax, the Bcl-2/Bax ratio, and Mcl-1 in 51 consecutive previously untreated CLL patients and 16 controls was determined by Western blotting. Only 37 patients were treated, all with chlorambucil and prednisone initially. Six patients achieved complete response (CR), 14 were non-responders (NR), and 17 had a partial response (PR), as defined by NCI criteria. There was considerable inter-patient variability in protein expression and overlap with healthy volunteers (P > 0.05). All patients with CR had low Mcl-1 levels compared to the PR + NR group (0.07 +/- 0.02 vs. 0.14 +/- 0.07, P = 0.043). Higher Mcl-1 expression as determined by dichotomizing the data was associated with a failure to achieve CR (P = 0.021). The Bcl-2/Bax ratio was significantly associated with treatment response only when CR and PR were considered together (0.89 +/- 0.53 [CR + PR] vs. 3.38 +/- 4.47 [NR], P = 0.0118). There was no association with Rai stage. Low Mcl-1 appears to be a requirement for CR, while low Bcl-2/Bax ratio is indicative of some response to conventional treatment.

Bcl-2 protein is required for the adenine/uridine-rich element (ARE)-dependent degradation of its own messenger

We have shown previously that the decay of human bcl-2 mRNA is mediated by an adenine/uridine-rich element (ARE) located in the 3'-untranslated region. Here, we have utilized a non-radioactive cell-free mRNA decay system to investigate the biochemical and functional mechanisms regulating the ARE-dependent degradation of bcl-2 mRNA. Using RNA substrates, mutants, and competitors, we found that decay is specific and ARE-dependent, although maximized by the ARE-flanking regions. In unfractionated extracts from different cell types and in whole cells, the relative enzymatic activity was related to the amount of Bcl-2 protein expressed by the cells at steady state. The degradation activity was lost upon Bcl-2 depletion and was reconstituted by adding recombinant Bcl-2. Ineffective extracts from cells that constitutively do not express Bcl-2 acquire full degradation activity by adding recombinant Bcl-2 protein. We conclude that Bcl-2 is necessary to activate the degradation complex on the relevant RNA target.

23-Hydroxybetulinic acid-mediated apoptosis is accompanied by decreases in bcl-2 expression and telomerase activity in HL-60 Cells

23-Hydroxybetulinic acid, a derivative of betulinic acid, was investigated for its apoptotic effect and the associated telomerase activity in human leukemia HL-60 cells. Apoptosis and bcl-2 were determined by flow cytometry analysis. A PCR-based telomeric repeat amplification protocol assay was used to detect telomerase activity. Results showed that 23-hydroxybetulinic acid induced growth arrest and apoptotic cell death in HL-60 cells. The apoptotic events were associated with concurrent down-regulation of bcl-2 and the telomerase activity. Our data suggest that 23-hydroxybetulinic acid may be a potential cytotoxic agent for treatment of cancer.

Dexamethasone-resistant human Pre-B leukemia 697 cell line evolving elevation of intracellular glutathione level: an additional resistance mechanism

Glucocorticoids remain among the most important drugs in the treatment of acute lymphoblastic leukemia (ALL). Although the mechanisms of glucocorticoid resistance have been studied in some T-cell leukemic cell lines, less work has been done with B-cell lines. We established a dexamethasone (DEX)-resistant human pre-B lineage leukemia cell line (697/DEX) and investigated the mechanism of resistance. 697/DEX was over 430-fold more resistant to DEX compared with the parental cells (697/Neo). Overexpression of Bcl-2 protein was not observed in 697/DEX, different from the mechanism of resistance in Bcl-2-virus-infected cells (697/Bcl-2). Although the expression of p-glycoprotein (Pgp) in 697/DEX was positive, its functional activity was not detected. The numbers of glucocorticoid receptors (GR) in 697/DEX and 697/Bcl-2 were significantly lower than those in 697/Neo. In addition, 697/DEX and 697/Bcl-2 had higher levels of glutathione (GSH) than 697/Neo. In the presence of L-buthionine-(S, R)-sulfoximine (BSO), an inhibitor of GSH synthesis, both 697/DEX and 697/Bcl-2 recovered their sensitivity to DEX. Interestingly, cell death by the depletion of GSH did not involve caspase-3/7 activation in 697/Bcl-2 and 697/DEX, different from 697/Neo, suggesting a death mechanism through caspase-independent programmed cell death or necrosis. In conclusion, DEX-resistance in 697/DEX was related not only to a GR decrease, but also to an increase in intracellular GSH level in the DEX-resistant B-cell leukemia cell line. Circumvention of DEX-resistance with BSO may offer an approach to overcoming resistance to chemotherapy in B-cell lineage ALL.

Rapamycin increases the cellular concentration of the BCL-2 protein and exerts an anti-apoptotic effect

The immunosuppressant rapamycin, an immunophilin-binding antibiotic, has been studied in follicular B-cell lymphoma lines that express the highest level of the BCL-2 protein. The growth rate of human follicular B-cell lymphoma lines was slowed more efficiently than that of other human B-cell lines or non-B-cell lines. This effect was dependent on the arrest of cells in the G(1) phase; the number of apoptotic cells was not increased. Rapamycin inhibited apoptosis or caspase activation induced by cytotoxic drugs, whereas caspase activation by doxorubicin was not inhibited. The increase in the cellular concentration of BCL-2 protein was related to its concentration in the steady state and was unrelated to the amount of bcl-2 mRNA. The increase of BCL-2 level in the cells rather than its level in the steady state may be important for drug resistance. The biochemical target of rapamycin, the mTOR kinase, may be a candidate sensitising agent for chemotherapy. This effect of rapamycin shows that G(1) arrest and protection from apoptosis are combined events susceptible to regulation by pharmacological means.

Damaged microtubules can inactivate BCL-2 by means of the mTOR kinase

Rapamycin, a specific inhibitor of the serine/threonine mTOR kinase, markedly inhibited both cell growth and apoptosis in human B-cell lines. Besides arresting cells in G(1) by increasing p27(kip1), rapamycin tripled the cellular level of the BCL-2 protein. The activity was dose-dependent and specific for the p27(kip1) and BCL-2 proteins. Rapamycin did not affect bcl-2 mRNA although it increased cellular BCL-2 concentration by inhibiting phosphorylation, a mechanism initiating the decay process. To add new insight, we combined rapamycin treatment with treatment by taxol, which, by damaging microtubules, can phosphorylate BCL-2 and activate apoptosis. It was found that the mTOR kinase was activated in cells treated with taxol or with nocodazole although it was inhibited in cells pre-treated with rapamycin. BCL-2 phosphorylation, apoptosis and hyperdiploidy were also inhibited by rapamycin. In contrast, taxol-induced microtubule stabilization or metaphase synchronization were not inhibited by rapamycin. Taken together, these findings indicate that mTOR belongs to the enzymatic cascade that, starting from damaged microtubules, phosphorylates BCL-2. By regulating apoptosis, in addition to the control of a multitude of growth-related pathways, mTOR plays a nodal role in signaling G(1) and G(2)-M events.

Differential regulation of P53, c-Myc, Bcl-2, Bax and AFP protein expression, and caspase activity during 10-hydroxycamptothecin-induced apoptosis in Hep G2 cells

10-Hydroxycamptothecin (HCPT), a DNA topoisomerase I (Topo I) inhibitor, exhibited a remarkable apoptosis-inducing effect on human hepatoma Hep G2 cells. We studied the effect of HCPT upon the expression of P53, c-Myc, Bcl-2, Bax and alpha-fetoprotein (AFP) proteins, and caspase (caspase-1 and caspase-3) activity of Hep G2 cells. It showed that HCPT at a dose of 0.1 microg/ml increased the expression of P53, c-Myc and Bax protein, and decreased the expression of Bcl-2 and AFP. The increase of P53, which was remarkable after only 3 h incubation with HCPT, occurred much earlier than the changes of other proteins, suggesting that the increase of P53 expression may be the upstream event in the apoptosis of Hep G2 cells induced by HCPT. Both caspase-1 and caspase-3 were activated in Hep G2 cells by HCPT treatment, suggesting that caspase-1 and caspase-3 are involved in the process of apoptosis in Hep G2 cells, and may be the main effectors of the apoptosis.

Follicular lymphoma can be distinguished from benign follicular hyperplasia by flow cytometry using simultaneous staining of cytoplasmic bcl-2 and cell surface CD20

The distinction between benign follicular hyperplasia (FH) and follicular lymphoma (FL) is sometimes problematic. We wanted to determine whether the expression of bcl-2 of FH was quantitatively different from that of FL, using surface CD20 expression as a discriminator of the various lymphoid compartments. Lymph node cell suspensions from 12 cases of FH and 17 cases of FL were analyzed by flow cytometry using a combined surface CD20 and intracellular bcl-2 staining. CD20- T cells in FH demonstrated the same bcl-2 expression as the CD20+ mantle cells, but the bright CD20+ germinal center cells showed near absence of bcl-2 expression. In contrast, the neoplastic cells of FL showed greater bcl-2 expression than the T cells of the same tumors and all cell populations of FH. This difference was particularly significant between the neoplastic B cells of FL and the germinal center cells of FH. The combined analysis of CD20 and bcl-2 should be useful for the differential diagnosis between FH and FL and particularly applicable to limited samples or when B-cell clonality is in question. Whether the quantitation of bcl-2 expression can be of further discriminatory value in malignant lymphomas remains to be determined.

The bfl-1 gene is transcriptionally upregulated by the Epstein-Barr virus LMP1, and its expression promotes the survival of a Burkitt's lymphoma cell line

The recently identified bfl-1 gene (also known as A1 or GRS), a homologue of bcl-2, encodes an antiapoptotic protein that suppresses apoptosis induced by the p53 tumor suppressor protein and exhibits proliferative and potent cooperative transforming activities. We show that elevated levels of bfl-1 mRNA are a feature of Epstein-Barr virus (EBV)-immortalized B-cell lines and Burkitt's lymphoma cell lines expressing the full spectrum of EBV latent proteins. Using an EBV-negative Burkitt's lymphoma cell line in which the expression of EBV latent membrane protein 1 (LMP1) is inducibly regulated by tetracycline, we demonstrate that LMP1 expression coincides with a dramatic increase in the level of bfl-1 mRNA. Also in this system, an increase in the level of Bcl-2 protein was seen to occur earlier than that of bcl-2 mRNA, suggesting that both transcriptional and translational mechanisms are involved in the control of Bcl-2 expression by LMP-1. We show that elevated bfl-1 mRNA stability can contribute to this effect of LMP-1, thus providing evidence of a novel mechanism of gene regulation by this EBV protein. Upregulation of bfl-1 by LMP1 was not observed in the T-cell line Jurkat or the epithelial cell line C33A. Ectopic expression of Bfl-1 in an EBV-positive cell line exhibiting a latency type I infection protects against apoptosis induced by growth factor deprivation, thereby providing a functional role for Bfl-1 in this cellular context and adding Bfl-1 to the list of antiapoptotic proteins whose expression is modulated by EBV. This is the first report of the regulation of bfl-1 expression by a viral protein, and this novel finding may thus represent an important link between the EBV oncoprotein LMP1 and its cellular growth-transforming properties.

Roles of p53, c-Myc, Bcl-2, Bax and caspases in glutamate-induced neuronal apoptosis and the possible neuroprotective mechanism of basic fibroblast growth factor

By using flow-cytometric analysis, we examined the involvement of p53, c-Myc, Bcl-2 and Bax in the glutamate-induced cell death in cultured cortical neurons. The activities of caspase-1-like and caspase-3-like proteases were also measured after the glutamate treatment. The apoptosis rate of the cells increased after 12 h and 24 h treatment with glutamate. The temporal profile of p53, c-Myc, Bcl-2, Bax expression and caspases activation after glutamate treatment suggest that Bcl-2, c-Myc and caspase-3 play important roles in the excitotoxic neuronal cell death. The down-regulation of Bcl-2 may be an important early stage event, which may cause the activation of caspase-3. c-Myc is also involved in the process of apoptosis though its precise role remains elusive. bFGF exhibited the capability to antagonize the neuronal apoptosis caused by glutamate. The antiapoptotic potential of bFGF may result from its attenuating effect on the down-regulation of Bcl-2 induced by glutamate and, subsequently, blockade of apoptosis cascade. This may provide a possible explanation for its neuroprotective effect against ischemic cell death.

CD22 Cross-Linking Generates B-Cell Antigen Receptor-Independent Signals That Activate the JNK/SAPK Signaling Cascade

CD22 is a B-cell–specific adhesion molecule that modulates BCR-mediated signal transduction. Ligation of human CD22 with monoclonal antibodies (MoAbs) that block the ligand binding site triggers rapid tyrosine phosphorylation of CD22 and primary B-cell proliferation. Because extracellular signal-regulated kinases (ERKs) couple upstream signaling pathways to gene activation and are activated by B-cell antigen receptor (BCR) signaling, we examined whether CD22 ligation also activated ERKs and/or modified BCR-induced ERK activation. Ligation of CD22 on either primary B cells or B-cell lines failed to significantly activate the mitogen activated protein kinase (MAPK) ERK-2, but did activate the stress-activated protein kinases (SAPKs; c-jun NH2-terminal kinases or JNKs). In contrast, BCR ligation resulted in ERK-2 activation without significant SAPK activation. Concurrent ligation of CD22 and BCR enhanced BCR-mediated ERK-2 activation without appreciably modulating CD22-induced SAPK activation. Consistent with its induction of SAPK activity, there was a marked increase in nuclear extracts of activator protein-1 (AP-1) and c-jun levels within 2 hours of exposure of primary B cells to the CD22 MoAb. Despite their differences in ERK activation, both CD22 and BCR ligation triggered several Burkitt lymphoma cell lines to undergo apoptosis, and the 2 stimuli together induced greater cell death than either signal alone. The pro-apoptotic effects were CD22-blocking MoAb-specific and dose-dependent. Examination of expression levels of Bcl-2 protoncogene family members (Bcl-2, Bcl-xL, Mcl-1, and Bax) showed a downregulation of Bcl-xL and Mcl-1 after CD22 ligation. This study provides a plausible mechanism to explain how CD22 and BCR signaling can costimulate B-cell proliferation and induce apoptosis in Burkitt lymphoma cell lines.

CD22 Cross-Linking Generates B-Cell Antigen Receptor-Independent Signals That Activate the JNK/SAPK Signaling Cascade

CD22 is a B-cell–specific adhesion molecule that modulates BCR-mediated signal transduction. Ligation of human CD22 with monoclonal antibodies (MoAbs) that block the ligand binding site triggers rapid tyrosine phosphorylation of CD22 and primary B-cell proliferation. Because extracellular signal-regulated kinases (ERKs) couple upstream signaling pathways to gene activation and are activated by B-cell antigen receptor (BCR) signaling, we examined whether CD22 ligation also activated ERKs and/or modified BCR-induced ERK activation. Ligation of CD22 on either primary B cells or B-cell lines failed to significantly activate the mitogen activated protein kinase (MAPK) ERK-2, but did activate the stress-activated protein kinases (SAPKs; c-jun NH2-terminal kinases or JNKs). In contrast, BCR ligation resulted in ERK-2 activation without significant SAPK activation. Concurrent ligation of CD22 and BCR enhanced BCR-mediated ERK-2 activation without appreciably modulating CD22-induced SAPK activation. Consistent with its induction of SAPK activity, there was a marked increase in nuclear extracts of activator protein-1 (AP-1) and c-jun levels within 2 hours of exposure of primary B cells to the CD22 MoAb. Despite their differences in ERK activation, both CD22 and BCR ligation triggered several Burkitt lymphoma cell lines to undergo apoptosis, and the 2 stimuli together induced greater cell death than either signal alone. The pro-apoptotic effects were CD22-blocking MoAb-specific and dose-dependent. Examination of expression levels of Bcl-2 protoncogene family members (Bcl-2, Bcl-xL, Mcl-1, and Bax) showed a downregulation of Bcl-xL and Mcl-1 after CD22 ligation. This study provides a plausible mechanism to explain how CD22 and BCR signaling can costimulate B-cell proliferation and induce apoptosis in Burkitt lymphoma cell lines.

Increased bcl-2 expression in lymphocytes and its association with hepatocellular damage in patients with autoimmune hepatitis

The proto-oncogene product bcl-2 is known to inhibit apoptotic cell death, and its dysregulation might play a critical role in the development of autoimmune disease. To elucidate the role of bcl-2 in autoimmune hepatitis (AIH), its expression in peripheral blood mononuclear cells (PBMC) and in liver-infiltrating lymphocytes (LIL) was investigated. Increased bcl-2 expression in PBMC was found in AIH patients compared with that in chronic hepatitis C (CHC) patients and in healthy controls. The level of bcl-2 expression significantly correlated with serum ALT level. Further analysis showed that CD4+ T cells are enriched in bcl-2-expressing PBMC. To characterize the Th1/Th2 profile of bcl-2-expressing CD4+ T cells, intracellular interferon-gamma (IFN-gamma) and IL-4 were analysed. The results revealed that most of the bcl-2-expressing cells were found to be IFN-gamma-secreting Th1 cells. In three patients for whom their clinical courses could be followed, bcl-2 expression was decreased after the initiation of immunosuppressive therapy with corticosteroids. However, the level of IFN-gamma + cells was not altered. Immunohistochemical analysis also showed that large amounts of bcl-2+ cells were observed in periportal area in the liver. In conclusion, bcl-2-expressing cells were shown to be increased in peripheral blood and liver in AIH and the bcl-2 product was expressed mainly in CD4+ Th1-type cells, suggesting that these cells might promote the cellular immune response and contribute to the development of hepatitis and hepatocellular damage in AIH.

In vitro treatment with retinoids decreases bcl-2 protein expression and enhances dexamethasone-induced cytotoxicity and apoptosis in multiple myeloma cells

All-trans retinoic acid (ATRA) has been shown to inhibit in vitro growth of multiple myeloma (MM) cells, and this effect can be further potentiated by the addition of Dexamethasone (DEX). We here extended this study by testing the activity of 9-cis retinoic acid (9-cis RA) and 13-cis retinoic acid (13-cis RA), both alone and in combination with DEX, in two MM cell lines, U266 and RPMI 8226. Furthermore, we aimed at investigating the mechanisms involved in the interactions of retinoids and DEX in this setting. 9-cis RA appeared to be the most active agent in U266 cell line (IC50 = 1.2 mumol/l vs 10.5 and 9.8 mumol/l obtained with ATRA and 13-cis RA, respectively) while, in RPMI 8226 cell line, 9-cis RA and 13-cis RA were almost equally cytotoxic (IC50 = 1 and 0.8 mumol/l) and ATRA was less effective. Co-incubation with DEX resulted in a synergistic cytotoxic activity in both the cell lines except for the combinations DEX + 9-cis RA in U266 cell line and DEX + 13-cis RA in RPMI 8226 cell line, where the effect was merely additive. A synergistic cytotoxic effect of retinoids and DEX was also observed on fresh MM cells obtained from 7 patients. Both retinoids and DEX are known to be inducers of apoptosis; we verified that the combined inhibitory activity of retinoids and DEX could be attributed to an increased induction of apoptosis. This effect may be mediated by a reduced intracellular expression of BCL-2 protein, which indeed observed after prolonged in vitro treatment with retinoids. It has been described recently that an enhanced expression of BCL-2 protein can contribute to the occurrence of early chemoresistance; the downregulation of BCL-2 protein induced by retinoids could thus be exploited, by means of novel chemotherapy plus retinoids combinations, in order to improve the efficacy of conventional chemotherapy in MM.

Arsenic trioxide inhibits growth of human T-cell leukaemia virus type I infected T-cell lines more effectively than retinoic acids

Adult T-cell leukaemia (ATL) is difficult to cure using conventional therapies. Recently the therapeutic possibility of retinoic acids (RA) has been reported. In this study, suppression of in vitro growth of human T-cell leukaemia virus type I (HTLV-I) infected T-cell lines and fresh ATL cells by arsenic trioxide (As2O3) were evaluated by comparison with a series of RA derivatives. Proliferation of four HTLV-I-infected T-cell lines was significantly reduced within 72 h by 1.0 micromol/l As2O3. Growth of two out of four HTLV-I-infected T-cell lines was also inhibited by 1.0 micromol/l RA, but to a lesser extent than by As2O3. The mechanism of this growth inhibition was due to the induction of apoptosis. Apoptosis was also induced in fresh ATL cells from patients by AS2O3, but far less by RA. As described in patients with acute promyelocytic leukaemia, 1.0 micromol/l of As2O3 can be safely achieved in the serum of patients; however, it is difficult to maintain this concentration of RA. In conclusion, As2O3 has therapeutic potential for the treatment of ATL and may be far more clinically beneficial than RA.

Detection of intracellular antigens by flow cytometry: comparison of two chemical methods and microwave heating

Detection of intracellular antigens by flow cytometry requires effective fixation and permeabilization of the cell membrane. This study compares three fixation/permeabilization techniques: two commercial chemical reagents, the ORTHOPermeaFixTM (OPF) and the FIX&PERM Cell Permeabilization Kit® (F&P), and a novel method based on microwave heating (MWH). They have been applied to the detection of two nuclear (p53 and rb/p105) and two cytoplasmic (bcl-2 and mdr-1/gp-170) antigens, using positive- and negative-control cell lines and peripheral blood mononuclear cells. Western blotting was performed as a control of protein expression. For the four antigens assessed, cellular morphology, discrimination between intact cells and debris, percentage of positive cells, and mean fluorescence intensity were examined. For this last parameter, the assessment of the MWH technique was performed using SD and a graphical approach inspired by the concepts described by Bland and Altman (Lancet 1986;346:1085–7) as well as Petersen et al. (Clin Chem 1997;43:2039–46). The statistical analysis shows that MWH is comparable to the commercial methods and that its reproducibility is also equivalent to OPF and F&P. As assessed for some of the most clinically relevant intracytoplasmic and intranuclear antigens, the MWH method appears to be a valuable and inexpensive alternative. It is worth noting that, unlike commercial reagents, MWH altered surface antigens. Interestingly, this feature, which would prevent cell selection on the basis of combined membrane and intracellular epitopes, is associated with a decrease of nonspecific background fluorescence.

Loss of p16/INK4A protein expression in non-Hodgkin's lymphomas is a frequent finding associated with tumor progression

The CDKN2A gene located on chromosome region 9p21 encodes the cyclin-dependent kinase-4 inhibitor p16/INK4A, a negative cell cycle regulator. We analyzed p16/INK4A expression in different types of non-Hodgkin's lymphoma to determine whether the absence of this protein is involved in lymphomagenesis, while also trying to characterize the genetic events underlying this p16/INK4A loss. To this end, we investigated the levels of p16/INK4A protein using immunohistochemical techniques in 153 cases of non-Hodgkin's lymphoma, using as reference the levels found in reactive lymphoid tissue. The existence of gene mutation, CpG island methylation, and allelic loss were investigated in a subset of 26 cases, using single-strand conformational polymorphism and direct sequencing, Southern Blot, polymerase chain reaction, and microsatellite analysis, respectively. Loss of p16/INK4A expression was detected in 41 of the 112 non-Hodgkin's lymphomas studied (37%), all of which corresponded to high-grade tumors. This loss of p16/INK4A was found more frequently in cases showing tumor progression from mucosa-associated lymphoid tissue low-grade lymphomas (31 of 37) or follicular lymphomas (4 of 4) into diffuse large B-cell lymphomas. Analysis of the status of the p16/INK4A gene showed different genetic alterations (methylation of the 5'-CpG island of the p16/INK4A gene, 6 of 23 cases; allelic loss at 9p21, 3 of 16 cases; and nonsense mutation, 1 of 26 cases). In all cases, these events were associated with loss of the p16/INK4A protein. No case that preserved protein expression contained any genetic change. Our results demonstrate that p16/INK4A loss of expression contributes to tumor progression in lymphomas. The most frequent genetic alterations found were 5'-CpG island methylation and allelic loss.

Bcl-2 expression and prognosis in childhood acute leukemia. Children's Cancer and Leukemia Study Group

Bcl-2 expression and its prognostic value were evaluated in 42 children with acute leukemia. The Bcl-2 expression of the leukemic blast cells was measured quantitatively by flow cytometry and was further analyzed by the simultaneous immunostaining of Bcl-2 with the surface membrane antigens, DNA, Ki-67 antigen. All of the cases showed a consistent expression of Bcl-2 protein; virtually all leukemic lymphoblasts were Bcl-2 positive. Although the expression of Bcl-2 varied widely from 7 to 80 x 10(3) MESF units, no significant difference was found in the mean value between the patients with acute lymphoblastic leukemia and those with acute myeloblastic leukemia. In more than half of the patients with AML, intraclonal heterogeneity of Bcl-2 expression was observed. The expression of Bcl-2 showed no apparent fluctuations during the different phases of the cell cycle. However, the proportion of Bcl-2-positive and -negative cells during the cell cycle was different between ALL and AML patients. In the ALL patients, few Bcl-2-negative cells were detected only in the GI phase, whereas in the AML patients Bcl-2-negative cells were detected in the S and G2/M phases, as well as in the G1 phase. No apparent difference was found in Bcl-2 expression between the Ki-67-negative noncycling population and the Ki-67-positive cycling population. Of the clinical features of these patients, only CD34 expression in the ALL patients was associated with high levels of Bcl-2 expression. In the 28 untreated cases of ALL, high expression of Bcl-2 was not an unfavorable factor for the outcome of this disease.

Increased ratio of bcl-2/bax expression is associated with bovine leukemia virus-induced leukemogenesis in cattle

To further investigate the molecular basis underlying the dysregulation of B cell homeostasis associated with bovine leukemia virus disease progression in cattle, bovine bax was cDNA cloned and sequenced. The predicted amino acid sequence of bovine Bax revealed a 192-amino-acid protein having extensive identity with the human (97%), murine (93%), and rat (94%) homologues. Because the ratio of Bcl-2 to Bax is believed to predetermine the susceptibility to a given apoptotic stimulus, the relative expression of the genes encoding these oncoproteins was evaluated in cattle naturally infected with BLV. In BLV-infected cattle an increase in the ratios of bcl-2/bax mRNA and protein expression correlated with advancing stages of disease. These findings suggest that in addition to the maintenance of BLV-associated hematopoietic malignancies, the reciprocal expression of Bcl-2/Bax may modulate the induction of B cell expansion typical of BLV disease progression.

Increased Apoptosis of T Cell Subsets in Aging Humans: Altered Expression of Fas (CD95), Fas Ligand, Bcl-2, and Bax

Aging is associated with lymphopenia and progressive decline in T cell functions; however, the mechanisms underlying these defects are unclear. We analyzed the expression of genes promoting apoptosis (fas/fasL1 and bax) and those inhibiting apoptosis (bcl-2 and bcl-xL) in lymphocytes from aging and young subjects at the protein level, using flow cytometry/Western blotting, and at the mRNA level, using quantitative PCR. Susceptibility of T cell subsets to undergo anti-Fas-induced apoptosis was analyzed by propidium iodide staining, TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) assay, DNA fragmentation assay, and staining with Hoechst 33342 dye. An increased expression of Fas and Fas ligand and a decreased expression of Bcl-2 were observed in both CD4+ and CD8+ T cells from aging as compared with young controls. Increased Fas and decreased Bcl-2 expression were also found in memory cells of both CD4+ and CD8+ T cell subsets from aging. Bax expression was increased in lymphocytes from aging at both the protein and mRNA level. No significant difference was observed in Bcl-xL expression between aging and young; however, the ratio of Bax:Bcl-xL was increased in aging. An increased proportion of CD4+ and CD8+ T cell subsets from aging underwent apoptosis following anti-Fas Ab treatment as compared with CD4+ and CD8+ T cell subsets from young controls. These data suggest that increased apoptosis may be one of the mechanisms responsible for lymphopenia and T cell deficiency associated with human aging.

The antisense bcl-2-IgH transcript is an optimal target for synthetic oligonucleotides

In most human follicular B cell lymphomas the bcl-2 gene is up-regulated as a result of the t(14;18) chromosomal translocation generating a hybrid bcl-2-IgH mRNA. Recently, we have identified in t(14;18)-positive cells a bcl-2-IgH mRNA in the antisense orientation, putatively responsible for the overexpression of bcl-2. Herein we show that this chimeric antisense transcript is an optimal target for synthetic oligodeoxynucleotides (ODNs). A variety of sense-oriented oligonucleotides have been designed that target the antisense transcript in regions endowed with a sequence specificity presumably restricted to an individual cell line (the bcl-2-IgH fusion regions) or extended to all t(14;18) cells (the ectopic bcl-2 segment upstream from the major breakpoint region and the IgH segment). All sense-oriented ODNs complementary to the antisense transcript induced an early strong inhibition of cell growth and a late fulminant cell death. As expected, the activity of ODNs targeting the fusion region was restricted to each individual cell line, whereas the activity of all ODNs targeting the common bcl-2 and IgH segments was extended to all t(14;18) cell lines tested. These sense ODNs were not effective in untranslocated cell lines. Antisense-oriented ODNs, complementary to the bcl-2-IgH mRNA, and control ODNs (scrambled, inverted, or mismatched) were biologically ineffective. The selectivity and efficacy of all sense ODNs tested provide support for the development of therapeutic ODNs targeting the bcl-2-IgH antisense transcript expressed in human follicular lymphomas.

Decreased expression of bcl-2 (p26) in CD8(+) lymphocytes of patients with T-cell lymphoproliferative disorders of large granular lymphocytes

The bcl-2 oncogene has been involved in the genesis of various B-cell neoplasms by means of encoding for p26, an apoptosis suppressor oncoprotein. The expression of p26 in lymphoproliferative disorders of large granular lymphocytes (LDLGL), a group of diseases whose mechanism leading to lymphocyte expansion is not yet clear, was not previously characterized. In order to further understand the biology of LDLGL, we compared the expression of p26 in CD8(+) lymphocytes of patients with CD3(+) LDLGL with that observed in normal individuals, patients with viral infection and patients with CD4(+) lymphoid neoplasms. We observed that upregulation of bcl-2 expression is not involved in the genesis of lymphocyte expansion in CD3(+) LDLGL. By contrast, when compared to normal peripheral blood counterparts, CD8(+, bright) lymphocytes of patients with LDLGL express low levels of p26 whereas CD8(+, dim) lymphocytes express normal or only slightly reduced levels of this oncoprotein. A similar pattern of expression of p26 was found in situations in which CD8(+) lymphocytes represent reactive activated cells.

Apoptosis induced in human colorectal carcinoma by anti-Fas antibody

BACKGROUND

Apoptosis or programmed cell death has been shown to play an important role in the progression from polyps to carcinomas. Fas/APO-1 is a cell surface protein that can induce apoptosis in a variety of cell types upon specific binding. In this study seven human colorectal carcinoma (HCRC) cell lines of varying differentiation were analyzed for cell surface Fas expression. Fas-mediated apoptosis, and correlation of apoptosis with bcl-2 expression.

METHODS AND RESULTS

Using flow cytometry, all seven lines expressed varying amounts of cell surface Fas antigen. Exposure to anti-Fas antibody induced cell death in all the cell lines, albeit to varying degrees. The rate of apoptosis was quantitated using flow cytometry with propidium iodide staining of nuclear DNA. The poorly differentiated cell lines had a significantly decreased (p < 0.05) anti-Fas sensitivity as compared with the well-differentiated lines. Measurement of bcl-2 expression by flow cytometry showed an inverse correlation with anti-Fas sensitivity.

CONCLUSIONS

This study confirms that HCRC cell lines express Fas antigen and, more importantly, provides the first evidence that exposure to anti-Fas antibody can induce apoptosis. Fas-mediated apoptosis in HCRC cell lines may be regulated by bcl-2 and may correlate with the degree of differentiation.

Protection from apoptotic cell death by interleukin-4 is increased in previously treated chronic lymphocytic leukemia patients

Chronic lymphocytic leukemia (CLL) cells were cultured in a medium supplemented with 0.01-1 ng/ml interleukin-4 (IL-4) for 18 h, fixed and analyzed on a flow cytometer. The percentage of apoptotic (AP) cells with hypodiploid DNA content was determined from DNA histograms. IL-4 at 0.01 ng/ml protected from spontaneous apoptosis of cells from previously treated CLL patients, but had very little effect on apoptotic death in cultures of cells from untreated patients. The number of AP cells in the absence of IL-4 was similar in cultures from treated and untreated patients. The concentration of IL-4 which inhibited spontaneous apoptosis by 50% was less than 0.01 ng/ml for pretreated patients and close to 1 ng/ml for untreated patients. Stage of the disease had no effect on the level of spontaneous apoptosis and its sensitivity to IL-4. Protection from apoptosis by IL-4 was not accompanied by the upregulation of bcl-2 protein. The number of AP cells in methylprednisolone hemisuccinate (MP) treated cultures from previously treated patients was significantly lower than in cultures from untreated patients in the presence of 0.01-1.0 ng/ml IL-4. Treatment with the combination L-phenylalanine mustard (L-PAM)+ fludarabine induced synergistic apoptotic response. Apoptosis induced by this combination was relatively resistant to IL-4 in patients treated with chlorambucil and prednisone, but not in patients previously treated with fludarabine. Protection from cytotoxicity by IL-4 may be one of the mechanisms of acquired drug resistance in CLL.

Maturation-dependent modulation of apoptosis in cultured cerebellar granule neurons by cytokines and neurotrophins

Immature cerebellar granule neurons die by apoptosis within 1 week in vitro unless maintained in depolarizing (high) concentrations of potassium (25 mM K+). Neurons allowed to survive and differentiate in high K+ medium for several days in vitro are still induced to undergo apoptosis when switched back to physiological (low) concentrations of K+ (5 mM). Here we have investigated the effects of various cytokines and growth factors in these two well-defined paradigms of neuronal apoptosis. Tumour necrosis factor-alpha, leukaemia inhibitory factor, ciliary neurotrophic factor, interleukin-10 and interleukin-13 delayed apoptosis and prolonged survival of cerebellar granule neurons maintained in low K+ medium. The effect observed required continuous exposure of the cultures to the cytokines and appeared not to involve modulation of Bcl-2 protein expression. Brain-derived neurotrophic factor accelerated neuronal death in low K+ medium. In contrast, when apoptosis of the neurons was precipitated by switching mature high K+ neurons to low K+ medium, neither tumour necrosis factor-alpha, leukaemia inhibitory factor, ciliary neurotrophic factor, interleukin-10 nor interleukin-13 prevented apoptosis. When testing the cytokines and growth factors for their capacity to alter N-methyl-D-aspartate receptor-mediated excitotoxicity of differentiated cerebellar granule neurons, no significant effect was observed. These data appear to define a maturation-dependent modulation of cerebellar granule cell survival by cytokines and neurotrophic factors that are expressed in a developmental pattern in the mammalian brain.

Rapid single-step method for flow cytometric detection of surface and intracellular antigens using whole blood

Fixation/permeabilization methods used for the detection of intracellular antigens by flow cytometry often result in the destruction of cellular morphology and surface immunoreactivity, properties useful in flow cytometry for the characterization of cells in heterogeneous populations. In addition, a majority of these methods are incompatible with whole blood and require that peripheral blood leukocytes (PBLs) be purified prior to fixation. This article describes a new technique for the rapid detection of both intracellular and cell surface antigens, while preserving cell morphology, through the use of a single-step fixation/permeabilization reagent, ORTHO PermeaFix (OPF). OPF is compatible with whole blood, allowing for the direct preparation of PBLs without prior cell separation. An additional red blood cell lysing reagent was not required because RBC lysis occurred upon resuspension of OPF-treated whole blood samples in isotonic solution. Discrimination of leukocyte populations by light scatter after OPF treatment was comparable to matched unfixed live cells. In addition, absolute lymphocyte and white blood cell (WBC) counts were not significantly affected when OPF-treated cells were compared with unfixed cells. Treatment of whole blood from 7 normal donors showed no significant difference in percentage of cells positive for CD2, CD3, CD4, CD8, CD16, or CD19 between fixed and unfixed samples when cells were stained before fixation, and no difference in CD3, CD4, CD8, CD16, or CD19 percentages when cells were stained following fixation. Monoclonal antibodies specific for intracellular antigens located at various sites within the cell were tested on fixed samples. OPF-treated peripheral blood lymphocytes showed greater than 95% reactivity for the inner mitochondrial membrane protein bcl-2, and the cytoskeletal cytoplasmic protein vimentin. TIA-1, a cytolytic granule-associated protein, showed differential reactivity within lymphocyte subsets, from a low of 8 +/- 2% in CD4+ cells to 89 +/- 6% in CD16+ cells, when whole blood from five normal donors was fixed and stained. Reh cells treated with OPF showed greater than 95% reactivity for the internuclear protein TdT. A comparison of OPF with two other fixation/permeabilization procedures, 1% paraformaldehyde followed by 45% ethanol and 0.25% paraformaldehyde followed by 0.2% Tween 20, showed that only OPF could be used both prior to or following cell surface staining with no effect on antigen detection while allowing optimal detection of all of the intracellular antigens tested.

Biological and clinical significance of in vitro prednisolone resistance in adult acute lymphoblastic leukaemia

It has been reported that in vitro prednisolone (PDN) resistance provides a prognostic value in childhood acute lymphoblastic leukaemia (ALL). This study aimed at investigating the biological and clinical significance of in vitro PDN resistance in adult ALL. Blast cells from 30 patients were exposed to PDN (0.1 microM-35 microM) and cytotoxicity was determined by the soluble tetrazolium formazan 2,3-bis (2-methoxy-4-nitro-5-sulphophenyl)-5-[(phenylamino) carbamyl]-2H-tetrazolium hydroxyde (XTT) colorimetric assay. The IC50 (defined as the drug concentration that results in 50% growth inhibition) varied greatly among the samples, from 0.3 microM to > 35 microM; 15 microM was subsequently chosen as IC50-cut-off point between in vitro resistant and sensitive cases. PDN-induced cytotoxicity was significantly related to apoptosis, as demonstrated by regression analysis; in sensitive cases, however, the percentage of apoptotic cells after in vitro PDN treatment was significantly increased compared with control (p = 0.002). Immunofluorescence evaluation of intracellular BCL-2 protein showed an equal percentage of positive cells in the two groups, but in resistant cells a higher mean fluorescence intensity (p = 0.04) was demonstrated. In vitro sensitive and resistant patients did not display differences in clinical characteristics, in cytological, karyotypic and immunophenotypic features and in the outcome of induction therapy. Disease-free survival (DFS), however, was significantly better in sensitive patients (p = 0.02).

Inhibition of Fas antigen-mediated apoptosis of rheumatoid synovial cells in vitro by transforming growth factor beta 1

OBJECTIVE

To investigate the mitogenic and anti-apoptotic effects of transforming growth factor beta 1 (TGF beta 1) on rheumatoid synovial cells in vitro.

METHODS

Synovial cells were cultured with or without TGF beta 1. After incubation, the proliferative response of synovial cells and the expression of Fas antigen and bcl-2 on synovial cells were examined. Finally, Fas antigen-mediated apoptosis of synovial cells was investigated by the addition of anti-Fas antibody.

RESULTS

TGF beta 1 enhanced the proliferation of synovial cells in a dose-dependent manner. In addition, Fas antigen expression on synovial cells was inhibited by the addition of TGF beta 1 with up-regulation of bcl-2 expression. The addition of anti-Fas antibody induced synovial cell apoptosis. However, stimulation of synovial cells with TGF beta 1 became markedly resistant to Fas antigen-mediated apoptosis. The results were not affected by the addition of a neutralizing antibody to platelet-derived growth factor type AA (PDGF-AA), which suggests that the effect of TGF beta 1 on synovial cells was promoted via PDGF-AA-independent mechanisms.

CONCLUSION

Our results suggest that TGF beta 1 promotes synovial cell proliferation through its mitogenic effect on synovial cells and interference with the apoptotic process mediated by the Fas antigen, resulting in the perpetuation of the synovial hyperplasia in patients with rheumatoid arthritis.

In vitro culture with prednisolone increases BCL-2 protein expression in adult acute lymphoblastic leukemia cells

The presence of BCL-2 gene rearrangement has been detected also in cellular populations lacking the t(14;18) chromosomal translocation, such as B-lineage acute lymphoblastic leukemia (ALL) cells. It has been reported that overexpression of BCL-2 is related to resistance to glucocorticoid-induced apoptosis. In this study, we aimed to evaluate whether in vitro culture with prednisolone (PDN) could modify the expression of BCL-2 protein. ALL cells from 21 patients were incubated for 72 hr with or without a minimally lethal (IC12) dose of PDN. In vitro culture with PDN did not affect the percentage of positive cells, even though the mean fluorescence index was significantly increased (P = 0.0001), thus indicating a higher level of protein production. These data could suggest a possible mechanism of drug resistance after treatment with PDN.

Applications of flow cytometry in the analysis of blood leukocytes

Flow cytometric analysis of blood leukocytes is currently used for both routine clinical measurements as well as for cutting edge research applications. This technology has enabled rapid and accurate determination of leukocyte antigens and quantitative analysis of leukocyte subsets, tests of leukocyte function, determination of the presence of antineutrophil and antilymphocyte antibodies in plasma and on cells, measurement of CD34+ hematpoietic stem cells in peripheral blood and bone marrow samples, measurement of apoptosis, and detection of virus-infected leukocytes. This review will focus on the use of the flow cytometer for investigations of blood leukocytes in transfusion medicine.