Apoptosis in lymphocytic leukemias and lymphomas

Clinical effect of standardized nursing for lymphoma patients and the influencing factors of nosocomial infection

To analyze the clinical effect of standardized nursing for lymphoma patients and the influencing factors of nosocomial infection, a total of 360 diffuse large B-cell lymphoma patients with disease recurrence or progression after first-line treatment were retrospectively selected from our hospital from January 2021 to July 2022. After standardized nursing, the overall infection rate of lymphoma patients was 2.50% (9/360), which was significantly lower than the overall infection rate of our hospital in 2021 (7.44%, 844/11342) (P < .05). The proportion of 3 kinds of pathogenic bacteria detected were G+ bacteria (33.5%), G- bacteria (53.3%), and fungi (13.2%). The pathogenic bacteria genus with the most G+ bacteria is Enterococcus, the pathogenic bacteria genus with the most G+ bacteria is Enterobacteriaceae, and the pathogenic bacteria with the most fungi is Candida albicans. Female infection rate was significantly higher than male (P < .05). There was no significant difference in nosocomial infection among different marital status/fertility status (P > .05). The nosocomial infection of patients with different hospitalization times was statistically significant (P < .05). The duration of hospitalization in the infected group was significantly higher than that in the non-infected group (P < .05). The clinical effect of standardized nursing for lymphoma patients is significant, and the influencing factors of nosocomial infection include patient gender, hospitalization frequency, and hospitalization duration.

Sanguinarine Induces Apoptosis Pathway in Multiple Myeloma Cell Lines via Inhibition of the JaK2/STAT3 Signaling

Sanguinarine (SNG), a benzophenanthridine alkaloid, has displayed various anticancer abilities in several vivo and in vitro studies. However, the anticancer potential of SNG is yet to be established in multiple myeloma (MM), a mostly incurable malignancy of plasma cells. In this study, we aimed to investigate the potential anti-proliferative and pro-apoptotic activities of SNG in a panel of MM cell lines (U266, IM9, MM1S, and RPMI-8226). SNG treatment of MM cells resulted in a dose-dependent decrease in cell viability through mitochondrial membrane potential loss and activation of caspase 3, 9, and cleavage of PARP. Pre-treatment of MM cells with a universal caspase inhibitor, Z-VAD-FMK, prevented SNG mediated loss of cell viability, apoptosis, and caspase activation, confirming that SNG-mediated apoptosis is caspase-dependent. The SNG-mediated apoptosis appears to be resulted from suppression of the constitutively active STAT3 with a concomitant increase in expression of protein tyrosine phosphatase (SHP-1). SNG treatment of MM cells leads to down-regulation of the anti-apoptotic proteins including cyclin D, Bcl-2, Bclxl, and XIAP. In addition, it also upregulates pro-apoptotic protein, Bax. SNG mediated cellular DNA damage in MM cell lines by induction of oxidative stress through the generation of reactive oxygen species and depletion of glutathione. Finally, the subtoxic concentration of SNG enhanced the cytotoxic effects of anticancer drugs bortezomib (BTZ) by suppressing the viability of MM cells via induction of caspase-mediated apoptosis. Altogether our findings demonstrate that SNG induces mitochondrial and caspase-dependent apoptosis, generates oxidative stress, and suppresses MM cell lines proliferation. In addition, co-treatment of MM cell lines with sub-toxic doses of SNG and BTZ potentiated the cytotoxic activity. These results would suggest that SNG could be developed into therapeutic agent either alone or in combination with other anticancer drugs in MM.

Sanguinarine suppresses growth and induces apoptosis in childhood acute lymphoblastic leukemia

Sanguinarine (Sang), a plant-derived compound isolated from the roots of Sanguinaria canadensis was evaluated for its potential pro-apoptotic effects in precursor B acute lymphoblastic leukemia (Pre-ALL) cell lines. Treatment of 697, REH, RS4;11, and SupB15 cell lines with Sang exhibited significant inhibition of cell viability via induction of apoptotic cell death. Sang-mediated apoptosis was found to be associated with the increased expression of proapoptotic bax with concomitant decrease of Bcl-2 expression leading to depolarization of mitochondria membrane resulting in loss of mitochondrial membrane potential (MMP). The reduced MMP caused the leakage in mitochondrial membrane and release of cytochrome c into the cytosol. The cytochrome c then mediates the activation of caspase-cascade and subsequently PARP cleavage. Furthermore, pretreatment with z-VAD-FMK, a pan-caspase inhibitor, abrogated Sang-induced inhibition of cell viability, induction of apoptosis. Sang treatment also reduced the phosphorylation of AKT and suppressed the expression of a number of anti-apoptotic genes such as cIAP1, cIAP2, and XIAP. Sang mediates its anti-cancer activity by generation of reactive oxygen species (ROS) due to depletion of glutathione level in leukemic cell lines. Pretreatment of these cells with N-acetyl cysteine (NAC) prevented Sang-induced depletion of glutathione level and mitochondrial-caspase-induced apoptosis. Finally, Sang treatment of Pre-ALL cell suppressed colony formation ability of these cells suggesting Sang has an anti-leukemic potential. Altogether, our data suggest that Sang is an efficient inducer of intrinsic apoptotic cell death via generation of ROS and exhibition of anti-leukemic effect in Pre-ALL cells raises the possibility to develop Sang as a therapeutic modality for the treatment and management of Pre-ALL.

Impaired apoptosis of megakaryocytes and bone marrow mononuclear cells in essential thrombocythemia: correlation with JAK2V617F mutational status and cytoreductive therapy

Essential thrombocythemia (ET) is a clonal myeloproliferative disorder characterized by overproduction of megakaryocytes (MKCs) and platelets. The recent discovery of the JAK2 mutation has shed a new light on the development of ET but its pathogenesis still remains unknown. One of the possible mechanisms can be deregulation of apoptosis, resulting in accumulation of bone marrow MKCs. In this study, we investigated the apoptotic profile, as well as the expression of apoptosis-regulating protein in MKCs and bone marrow mononuclear cells (BMMCs) in 43 patients with ET. We found significantly lower percentages of apoptotic MKCs and BMMCs, as measured by the rate of annexin-V+ and caspase-3+ (Cas-3+) cells in relation to healthy volunteers. Additionally, the expression of Bax protein in ET patients naïve to cytoreductive treatment, as well as their Bax/Bcl-2 ratio, was significantly lower than in controls (p=<0.05 and p<0.001, respectively). Patients positive for the JAK2V617F mutation had markedly higher activation of Cas-3, as well as higher Bax expression (p=0.02 and p=0.04, respectively) than JAK2V617F negative cases. There were no marked differences between patients already treated with anagrelide (ANA) or hydroxyurea (HU), although tendency toward the higher apoptosis rate was observed in the HU-treated group. In conclusion, these results demonstrate the inhibition of caspase-dependent apoptosis of both MKCs and BMMCs in untreated ET. This is associated with upregulation of Bcl-2 and downregulation of Bax proteins, predominantly in JAK2V617F negative cases. Patients treated with HU showed slightly higher pro-apoptotic Bax/Bcl-2 index than patients on ANA therapy, which may influence the better efficacy of HU therapy in ET.

Viral Helicases

Helicases are motor proteins that use the free energy of NTP hydrolysis to catalyze the unwinding of duplex nucleic acids. Helicases participate in almost all processes involving nucleic acids. Their action is critical for replication, recombination, repair, transcription, translation, splicing, mRNA editing, chromatin remodeling, transport, and degradation (Matson and Kaiser-Rogers 1990; Matson et al. 1994; Mendonca et al. 1995; Luking et al. 1998).

Oxidative Upregulation of Bcl-2 in Healthy Lymphocytes

In many cell systems, pharmacological glutathione (GSH) depletion with the GSH neosynthesis inhibitor buthionine sulfoximine (BSO) leads to cell death and highly sensitizes tumor cells to apoptosis induced by standard chemotherapeutic agents. However, some tumor cells upregulate Bcl-2 in response to BSO, thus surviving the treatment and failing to be chemosensitized. Cell lines of monocytic and lymphocytic origins respond to BSO treatment in an opposite way, lymphocytes being chemosensitized and unable to transactivate Bcl-2. In this article we investigate the response to BSO of lymphocytes freshly isolated from peripheral blood of healthy donors. After ensuring that standard separation procedures do not alter per se lymphocytes redox equilibrium nor Bcl-2 levels in the first 24 h of culture, we show that BSO treatment promotes the upregulation of Bcl-2, with a mechanism involving the increased radical production consequent to GSH depletion. Thus, BSO treatment may increase the differential cytocidal effect of cytotoxic drugs in tumor versus normal lymphocytes.

An inducible caspase 9 safety switch for T-cell therapy

The efficacy of adoptive T-cell therapy as treatment for malignancies may be enhanced by genetic modification of infused cells. However, oncogenic events due to vector/transgene integration, and toxicities due to the infused cells themselves, have tempered enthusiasm. A safe and efficient means of removing aberrant cells in vivo would ameliorate these concerns. We describe a "safety switch" that can be stably and efficiently expressed in human T cells without impairing phenotype, function, or antigen specificity. This reagent is based on a modified human caspase 9 fused to a human FK506 binding protein (FKBP) to allow conditional dimerization using a small molecule pharmaceutical. A single 10-nM dose of synthetic dimerizer drug induces apoptosis in 99% of transduced cells selected for high transgene expression in vitro and in vivo. This system has several advantages over currently available suicide genes. First, it consists of human gene products with low potential immunogenicity. Second, administration of dimerizer drug has no effects other than the selective elimination of transduced T cells. Third, inducible caspase 9 maintains function in T cells overexpressing antiapoptotic molecules. These characteristics favor incorporation of inducible caspase 9 as a safety feature in human T-cell therapies.

Pro-apoptotic therapy with the oligonucleotide Genasense (oblimersen sodium) targeting Bcl-2 protein expression enhances the biological anti-tumour activity of rituximab

New strategies have evolved in the treatment of patients with non-Hodgkin's lymphoma (NHL). Anti-sense oligonucleotides (ASO) and monoclonal antibody (mAb) therapy, though proven to be safe and effective, have not demonstrated to be curative when used as single agents. We tested an innovative combination strategy involving various mAbs and ASO against Bcl-2 (G3139) in aggressive preclinical models. G3139, under optimal transfection conditions, decreased the proliferation rate of lymphoma cells by 60-75% when compared with controls. In addition, apoptosis was demonstrated in Raji (25%) and DHL-4 cells (30%) treated with Genasense following downregulation of Bcl-2 protein. Downregulation of Bcl-2 by G3139 was associated with a higher degree of rituximab-associated, complement-mediated cytotoxicity and antibody dependent cellular cytotoxicity when compared with rituximab alone-treated controls. In vivo studies in severe combined immunodeficiency (SCID) mice clearly demonstrated synergistic activity between G3139 and rituximab. Treatment of lymphoma-bearing SCID mice with G3139 for two consecutive days prior to each rituximab dose resulted in better disease control and survival than treatment with either agent alone or controls. Our findings suggest that Bcl-2 downregulation by G3139, followed by the administration of rituximab is an efficient anti-tumour strategy associated with improved survival in lymphoma-bearing SCID mice.

Substitution of HIV Type 1 Nef with HTLV-1 p12

Human retroviruses, such as HTLV-1 and HIV-1, encode accessory proteins, which regulate viral pathogenesis. The p12 protein of HTLV-1 is encoded from the pX-I open reading frame, and is critical for efficient virus replication in rabbits. Although dispensable for infection, replication, and immortalization of activated lymphocytes in culture, p12 expression is important for infection of quiescent lymphocytes. Similar to HTLV-1 p12, Nef is important for virus infectivity in SIV animal models. We questioned whether p12 could replace Nef in HIV-1, and reconstitute virus replication in culture. We found that p12 could complement for effects of Nef on HIV-1 infection of Magi-CCR5 cells or macrophages.

Bcr-Abl-mediated molecular mechanism for apoptotic suppression in multipotent haemopoietic cells: a role for PKCbetaII

Bcr-Abl protein tyrosine kinase (PTK) activity is a feature of chronic myeloid leukaemia and confers a survival advantage on haemopoietic progenitor cells. We have expressed conditional mutant of the Bcr-Abl PTK in the FDCP-Mix A4 multipotent haematopoietic cell line in order to examine the molecular mechanisms whereby Bcr-Abl PTK leads to enhanced cell survival under conditions in which normal cells die. Activation of Bcr-Abl PTK does not phosphorylate or activate either ERK-1/2 or JAK-2/STAT-5b, suggesting that these signal transduction pathways are not involved in Abl PTK-mediated suppression of apoptosis in FDCP-Mix cells. However, protein kinase C (PKC) does have a role to play. Inhibition of PKC results in a reversal of Bcr-Abl PTK-mediated survival in the absence of growth factor and Bcr-Abl stimulates translocation of the PKCbetaII isoform to the nucleus. Furthermore, expression of a constitutively activated PKCbetaII in haemopoietic progenitor FDCP-Mix cells stimulates enhanced cell survival when IL-3 is withdrawn. However, expression of this constitutively activated PKC isoform does not suppress cytotoxic drug-induced apoptosis. Thus Bcr-Abl PTK has pleiotropic effects which can suppress cell death induced by a number of stimuli.

Adenoviral gene transfer of erythropoietin confers cytoprotection to isolated pancreatic islets

BACKGROUND

The transfer of cytoprotective genes to isolated pancreatic islets may contribute to their enhanced survival in the transplant setting. Our laboratory established the expression of functional erythropoietin (EPO) receptors throughout pancreatic islets. Because EPO is a cytokine that promotes survival, we examined whether adenovirus-mediated gene transfer of EPO would result in cytoprotection of human pancreatic islets in culture and in the transplant setting.

METHODS

Isolated human islets were transduced using an adenoviral vector coding for human EPO or green fluorescent protein. Comparison of cell death in culture was measured using annexin V-phycoerythrin and propidium iodide. Transplantation of transduced islets into diabetic nude mice was used to assess the effect of EPO on islet function and in vivo survival.

RESULTS

Adenoviral delivery of EPO to pancreatic islets resulted in high-level EPO synthesis and secretion, which did not affect islet function in vitro or in vivo. Islets transduced with EPO were protected from apoptosis in culture and were at a functional advantage in vivo when compared with islets transduced with green fluorescent protein or untransduced islets. The high level of EPO had a negative effect on the blood chemistry of the animals that underwent transplantation.

CONCLUSIONS

Overexpression of EPO protects islets from destruction and does not compromise islet function. Genetic engineering with EPO may be a viable approach for improving islet survival and engraftment in the transplant setting, but regulation of the gene's expression will be an important prerequisite to this strategy.

B-cell homeostasis: digital survival or analog growth?

Maintenance of B-lymphocyte homeostasis requires balanced cell production, death, and proliferation. To coordinate these processes, B cells are dependent on cell extrinsic signals. In lymphocyte development, precursor cells are dependent on Fms-like tyrosine kinase ligand 3 (Flt3L), and pre-B cells are dependent on the cytokine interleukin-7. Transitional B cells require B-lymphocyte stimulator (BLyS) for survival. Mature B cells require B-cell receptor (BCR) signals and also remain sensitive to their microenvironment. An emerging model suggests that extrinsic signals do not regulate B-cell survival through a digital mechanism where cells are simply instructed to survive or die. Instead, availability and competition for extrinsic signals regulates cellular physiology and metabolism in an analog fashion that then influences cell commitment to apoptosis or proliferation. Decreases in cellular metabolism may sensitize cells to activation and action of the pro-apoptotic Bcl-2 family members, Bak and Bax, and promote apoptosis. In contrast, increases in metabolism may predispose cells to proliferate. Analog control of cell physiology can, thus, be integrated with other inputs by individual cells to produce a fate decision for survival, proliferation, or apoptosis and prevent diseases of cell death, such as immunodeficiency, and cell activation and proliferation, such as autoimmunity or cancer.

hIan5: the human ortholog to the rat Ian4/Iddm1/lyp is a new member of the Ian family that is overexpressed in B-cell lymphoid malignancies

The family of immune associated nucleotide binding proteins (Ian) is a distinct family of GTP-binding proteins conserved in plants, mice, rats and humans that are associated with immune functions, suggesting involvement in conserved defense mechanisms. Recently, the rat Ian4 (rIan4) was cloned and it appears to be identical to the gene Iddm1/lyp responsible for severe lymphopenia and the development of insulin-dependent diabetes in the BB-DP rat. Here we describe the characterization of a new human member of the Ian family: hIan5. hIan5 is highly homologous to rIan4, has a predicted molecular weight of 35 kDa and contains distinct G motifs of GTP-binding proteins (G-1 to G-4) in the N-terminus. Human Ian5 is anchored to the mitochondria by the hydrophobic COOH-terminal domain. Human Ian5 is highly expressed in lymph node and spleen. Different blood fractions show high hIan5 expression in CD4- and CD8-positive T cells and monocytes, but not in B lymphocytes. In contrast, in B-CLL (chronic lymphocytic leukemia) and mantle cell lymphoma samples, hIan5 mRNA was upregulated. The current data underline the role of hIan5 in T-lymphocyte development and function, and for the first time suggest that upregulation of Ian proteins is associated with B-cell malignancy, possibly by inhibiting apoptosis.

Reduced cell turnover in bovine leukemia virus-infected, persistently lymphocytotic cattle

Although nucleotide analogs like bromodeoxyuridine have been extensively used to estimate cell proliferation in vivo, precise dynamic parameters are scarce essentially because of the lack of adequate mathematical models. Besides recent developments on T cell dynamics, the turnover rates of B lymphocytes are largely unknown particularly in the context of a virally induced pathological disorder. Here, we aim to resolve this issue by determining the rates of cell proliferation and death during the chronic stage of the bovine leukemia virus (BLV) infection, called bovine persistent lymphocytosis (PL). Our methodology is based on direct intravenous injection of bromodeoxyuridine in association with subsequent flow cytometry. By this in vivo approach, we show that the death rate of PL B lymphocytes is significantly reduced (average death rate, 0.057 day(-1) versus 0.156 day(-1) in the asymptomatic controls). Concomitantly, proliferation of the PL cells is also significantly restricted compared to the controls (average proliferation rate, 0.0046 day(-1) versus 0.0085 day(-1)). We conclude that bovine PL is characterized by a decreased cell turnover resulting both from a reduction of cell death and an overall impairment of proliferation. The cell dynamic parameters differ from those measured in sheep, an experimental model for BLV infection. Finally, cells expressing p24 major capsid protein ex vivo were not BrdU positive, suggesting an immune selection against proliferating virus-positive lymphocytes. Based on a comparative leukemia approach, these observations might help to understand cell dynamics during other lymphoproliferative disease such as chronic lymphocytic leukemia or human T-cell lymphotropic virus-induced adult T-cell leukemia in humans.

Induction of caspase-dependent programmed cell death in B-cell chronic lymphocytic leukemia by anti-CD22 immunotoxins

B cells of chronic lymphocytic leukemia (CLL) are long-lived in vivo, possibly because of defects in apoptosis. We investigated BL22, an immunotoxin composed of the Fv portion of an anti-CD22 antibody fused to a 38-kDa Pseudomonas exotoxin-A fragment. B cells from 22 patients with CLL were immunomagnetically enriched (96% purity) and were cultured with BL22 or an immunotoxin that does not recognize hematopoietic cells. The antileukemic activity of BL22 was correlated with CD22 expression, as determined by flow cytometry. BL22 induced caspase-9 and caspase-3 activation, poly(adenosine diphosphate [ADP]-ribose)polymerase (PARP) cleavage, DNA fragmentation, and membrane flipping. Cell death was associated with the loss of mitochondrial membrane potential and the down-regulation of Mcl-1 and X-chromosomal inhibitor of apoptosis protein (XIAP). Furthermore, BL22 induced a proapoptotic 18-kDa Bax protein and conformational changes of Bax. Z-VAD.fmk abrogated apoptosis, confirming that cell death was executed by caspases. Conversely, interleukin-4, a survival factor, inhibited spontaneous death in culture but failed to prevent immunotoxin-induced apoptosis. BL22 cytotoxicity was markedly enhanced when combined with anticancer drugs including vincristine. We also investigated HA22, a newly engineered immunotoxin, in which BL22 residues are mutated to improve target binding. HA22 was more active than BL22. In conclusion, these immunotoxins induce caspase-mediated apoptosis involving mitochondrial damage. Combination with chemotherapy is expected to improve the efficacy of immunotoxin treatment.

Anticancer drugs of tomorrow: apoptotic pathways as targets for drug design

Apoptosis or programmed cell death is a set of ordered events that enables the selective removal of cells from tissue and is essential for homeostasis and proper function of multicellular organisms. Components of this signaling network, which include ligands, such as CD95, tumor necrosis factor (TNF) and TNF-related apoptosis-inducing ligand, as well as downstream molecules, such as caspases, Bcl-2 family members, and inhibitor-of-apoptosis proteins, which trigger and regulate apoptosis, are crucial targets for conventional drug development and gene therapy of cancer and other diseases. Here, we focus on apoptotic pathways and propose new potential molecular targets that could prove effective in controlling cell death in the clinical setting.