Can gas replace protein function? CO abrogates the oxidative toxicity of myoglobin.

Outside their cellular environments, hemoglobin (Hb) and myoglobin (Mb) are known to wreak oxidative damage. Using haptoglobin (Hp) and hemopexin (Hx) the body defends itself against cell-free Hb, yet mechanisms of protection against oxidative harm from Mb are unclear. Mb may be implicated in oxidative damage both within the myocyte and in circulation following rhabdomyolysis. Data from the literature correlate rhabdomyolysis with the induction of Heme Oxygenase-1 (HO-1), suggesting that either the enzyme or its reaction products are involved in oxidative protection. We hypothesized that carbon monoxide (CO), a product, might attenuate Mb damage, especially since CO is a specific ligand for heme iron. Low density lipoprotein (LDL) was chosen as a substrate in circulation and myosin (My) as a myocyte component. Using oxidation targets, LDL and My, the study compared the antioxidant potential of CO in Mb-mediated oxidation with the antioxidant potential of Hp in Hb-mediated oxidation. The main cause of LDL oxidation by Hb was found to be hemin which readily transfers from Hb to LDL. Hp prevented heme transfer by sequestering hemin within the Hp-Hb complex. Hemin barely transferred from Mb to LDL, and oxidation appeared to stem from heme iron redox in the intact Mb. My underwent oxidative crosslinking by Mb both in air and under N2. These reactions were fully arrested by CO. The data are interpreted to suit several circumstances, some physiological, such as high muscle activity, and some pathological, such as rhabdomyolysis, ischemia/reperfusion and skeletal muscle disuse atrophy. It appear that CO from HO-1 attenuates damage by temporarily binding to deoxy-Mb, until free oxygen exchanges with CO to restore the equilibrium.

Carbon monoxide promotes respiratory hemoproteins iron reduction using peroxides as electron donors.

The physiological role of the respiratory hemoproteins (RH), hemoglobin and myoglobin, is to deliver O(2) via its binding to their ferrous (Fe(II)) heme-iron. Under variety of pathological conditions RH proteins leak to blood plasma and oxidized to ferric (Fe(III), met) forms becoming the source of oxidative vascular damage. However, recent studies have indicated that both metRH and peroxides induce Heme Oxygenase (HO) enzyme producing carbon monoxide (CO). The gas has an extremely high affinity for the ferrous heme-iron and is known to reduce ferric hemoproteins in the presence of suitable electron donors. We hypothesized that under in vivo plasma conditions, peroxides at low concentration can assist the reduction of metRH in presence of CO. The effect of CO on interaction of metRH with hydrophilic or hydrophobic peroxides was analyzed by following Soret and visible light absorption changes in reaction mixtures. It was found that under anaerobic conditions and low concentrations of RH and peroxides mimicking plasma conditions, peroxides served as electron donors and RH were reduced to their ferrous carboxy forms. The reaction rates were dependent on CO as well as peroxide concentrations. These results demonstrate that oxidative activity of acellular ferric RH and peroxides may be amended by CO turning on the reducing potential of peroxides and facilitating the formation of redox-inactive carboxyRH. Our data suggest the possible role of HO/CO in protection of vascular system from oxidative damage.

Carbon monoxide induced erythroid differentiation of K562 cells mimics the central macrophage milieu in erythroblastic islands.

Growing evidence supports the role of erythroblastic islands (EI) as microenvironmental niches within bone marrow (BM), where cell-cell attachments are suggested as crucial for erythroid maturation. The inducible form of the enzyme heme oxygenase, HO-1, which conducts heme degradation, is absent in erythroblasts where hemoglobin (Hb) is synthesized. Yet, the central macrophage, which retains high HO-1 activity, might be suitable to take over degradation of extra, harmful, Hb heme. Of these enzymatic products, only the hydrophobic gas molecule--CO can transfer from the macrophage to surrounding erythroblasts directly via their tightly attached membranes in the terminal differentiation stage.Based on the above, the study hypothesized CO to have a role in erythroid maturation. Thus, the effect of CO gas as a potential erythroid differentiation inducer on the common model for erythroid progenitors, K562 cells, was explored. Cells were kept under oxygen lacking environment to mimic BM conditions. Nitrogen anaerobic atmosphere (N2A) served as control for CO atmosphere (COA). Under both atmospheres cells proliferation ceased: in N2A due to cell death, while in COA as a result of erythroid differentiation. Maturation was evaluated by increased glycophorin A expression and Hb concentration. Addition of 1%CO only to N2A, was adequate for maintaining cell viability. Yet, the average Hb concentration was low as compared to COA. This was validated to be the outcome of diversified maturation stages of the progenitor's population.In fact, the above scenario mimics the in vivo EI conditions, where at any given moment only a minute portion of the progenitors proceeds into terminal differentiation. Hence, this model might provide a basis for further molecular investigations of the EI structure/function relationship.

Salvage chemotherapy with dexamethasone, etoposide, ifosfamide and cisplatin (DVIP) for relapsing and refractory non-Hodgkin's lymphoma.

BACKGROUND: There is currently no standard salvage chemotherapy for the 40-50% of patients with non-Hodgkin's lymphoma who fail first-line treatment. OBJECTIVES: To review the experience of a major tertiary medical center with DVIP (dexamethasone, etoposide, ifosfamide and cisplatin) salvage therapy for primary refractory/relapsing NHL. METHODS: We reviewed the records of all patients with NHL who received DVIP salvage therapy during the period 1993 to 2005. RESULTS: We identified 37 adult patients (mean age 56.3 years): 29 with aggressive lymphoma and 8 with indolent lymphoma. Mean event-free survival was 13.5 months (range 0-82 months), mean time between diagnosis and DVIP treatment 18.5 months (range 2-101), and mean number of DVIP cycles 1.9. Four patients (11%) achieved a complete response and 9 (24%) a partial response (overall response 35%). Consolidation with stem cell transplantation was used in 14 patients with aggressive lymphoma and 4 with indolent lymphoma; 14 patients, all with aggressive lymphoma, responded (12 complete, 2 partial). Of the 10 patients who underwent SCT despite no response to salvage DVIP, 6 achieved a complete response. Five year overall survival since the diagnosis for the whole sample was 39.4 +/- 8.7%, and 5 year post-DVIP overall survival 37.6 +/- 8.0%. On multivariate analysis, SCT was the strongest predictor of survival (relative risk 0.73, P < 0.0001) followed by a high score on the International Prognostic Index (RR 3.71, P = 0.032). CONCLUSIONS: DVIP salvage therapy for NHL was associated with a low response rate of 35% but a 5 year post-DVIP survival rate of 37.6%. Patients who are refractory to salvage treatment with DVIP might still be salvaged with SCT.

Antiphospholipid antibodies may be a new prognostic parameter in aggressive non-Hodgkin's lymphoma.

OBJECTIVES: Patients with malignancies have an increased prevalence of antiphospholipid antibodies (APA). The aim of this study was to determine the prevalence of IgG, IgM, and IgA anticardiolipin antibodies (aCL) and anti-beta-2 glycoprotein I antibodies (anti-beta2-GPI) in patients with non-Hodgkin's lymphoma (NHL), and to investigate their clinical and prognostic significance. METHODS: The study group included 86 patients with NHL. Enzyme-linked immunosorbent assay kits were used to measure the concentrations of aCL and anti-beta2-GPI, and coagulation tests, to measure lupus anticoagulant (LAC) activity. Blood was collected at diagnosis in all patients and at follow-up in 15. Median follow-up time was 1.9 yr. RESULTS: Elevated APA levels were found in 35 patients (41%) at diagnosis: one patient aCL IgG, five patients aCL IgM, five aCL IgA, one anti-beta2-GPI IgG, 14 anti-beta2-GPI IgM, and 19 anti-beta2-GPI IgA; LAC activity was found in three of 67 patients (4.5%). There was no significant correlation between elevated APA levels and patient's age or sex, disease stage or grade, bone marrow involvement, B symptoms, serum lactate dehydrogenase levels, serum beta2 microglobulin levels, International Prognostic Index (IPI) score, performance status, type of treatment, or response to treatment. There was a correlation between elevated APA and absence of extranodal disease (P = 0.045). A strong negative correlation was found between elevated APA at diagnosis and survival time. Two-year survival was 90 +/- 5% for patients without APA at diagnosis compared with 63 +/- 11% for patients with an elevated APA levels (P = 0.0025). APA added to the predictive value of IPI for event-free and overall survival. CONCLUSIONS: APA are elevated in 41% of NHL patients at diagnosis and are correlated with shortened survival. Their level may serve as an independent prognostic variable in aggressive NHL.

Jasmonates: novel anticancer agents acting directly and selectively on human cancer cell mitochondria.

We reported previously that jasmonates can kill human cancer cells. Many chemotherapeutic drugs induce mitochondrial membrane permeability transition, membrane depolarization, osmotic swelling, and release of cytochrome c, involving the opening of the permeability transition pore complex (PTPC). Because jasmonates exert their cytotoxic effects independent of transcription, translation, and p53 expression, we hypothesized that these compounds may act directly on mitochondria. Mitochondrial membrane depolarization was determined by flow cytometry, and cytochrome c release by Western blotting. Mitochondria were isolated by mechanical lysis and differential centrifugation. Cytotoxicity was measured by a tetrazolium-based assay, and mitochondrial swelling by spectrophotometry. Jasmonates induced membrane depolarization and cytochrome c release in intact human cancer cell lines. Jasmonates induced swelling in mitochondria isolated from Hep 3B hepatoma cells, but not in mitochondria isolated from 3T3 nontransformed cells or from normal lymphocytes, in a PTPC-mediated manner. Methyl jasmonate induced the release of cytochrome c from mitochondria isolated from cancer cell lines in a PTPC-mediated manner, but not from mitochondria isolated from normal lymphocytes. A correlation was found between cytotoxicity of methyl jasmonate and the percentage of leukemic cells in the blood of patients with chronic lymphocytic leukemia (CLL). Jasmonates induced membrane depolarization in CLL cells, and swelling and release of cytochrome c in mitochondria isolated from these cells. In conclusion, jasmonates act directly on mitochondria derived from cancer cells in a PTPC-mediated manner, and could therefore bypass premitochondrial apoptotic blocks. Jasmonates are promising candidates for the treatment of CLL and other types of cancer.

Expression of adhesion molecules on leukemic B cells from chronic lymphocytic leukemia patients with predominantly splenic manifestations.

BACKGROUND: The highly tissue-specific trafficking of normal and malignant lymphocytes to particular organs is mediated by adhesion molecules, or "homing receptors." Among our patients with B cell chronic lymphocytic leukemia 15% demonstrate predominantly splenic manifestations and are classified as stage II(S). OBJECTIVE: To investigate whether expression of cell surface adhesion molecules can distinguish stage II(S) patients from stage 0 or stage 0 and I CLL patients. METHODS: Expression of adhesion molecules belonging to different families was studied in CD19-positive cells isolated from the blood of 42 patients by dual color flow cytometry. The families included: immunoglobulin superfamily (CD54, CD58), integrin family (beta1, beta2 and beta3 chains, CD11a, CD11c, CD49d), selectin family (L-selectin), and lymphocyte homing receptor family (CD44). RESULTS: The average percentage of leukemic cells expressing CD11c in the 23 patients with stage II(S) was 25.7 compared with 13.2% in the 14 patients with stage 0 disease (P = 0.047). The average percentage of leukemic cells expressing CD44 in patients with stage II(S) was 90.5 compared with 77.2% in patients with stage 0 (P = 0.007) and 80% in patients with stages 0 and I together (n = 19, P = 0.008). Other adhesion molecules tested did not show a statistically significance difference in expression between the different disease stages. CONCLUSIONS: The higher expression of CD44 and CD11c in cells of CLL patients with predominantly splenic manifestations may account for the tendency of their lymphocytes to home to the spleen.

Serum CA 125 as a prognostic factor in non-Hodgkin's lymphoma.

Cancer antigen 125 (CA 125) is a glycoprotein expressed in normal tissues originally derived from coelomic epithelia such as peritoneum, pleura, pericardium, fallopian tubes and endometrium. Serum CA 125 levels are elevated in various benign and malignant conditions that involve stimulation of these tissues. Although elevated levels have been reported in patients with non-Hodgkin's lymphoma (NHL), its role as a prognostic factor remained uncertain. In this study, serum CA 125 levels were measured prospectively in 108 consecutive patients with NHL: at diagnosis in 106, in remission in 39 and at relapse in 7. Levels were elevated in 43% at diagnosis. This finding was associated with advanced disease stage, bulky tumors, bone marrow involvement, extranodal disease (in stages III and IV), occurrence of B symptoms, pleural or peritoneal effusions, high serum LDH levels, high serum beta2 microglobulin (beta2-M) levels, elevated International Prognostic Score, poor performance status and partial or no response to treatment. No difference in CA 125 level was found between the indolent and aggressive lymphomas. Serum CA 125 levels at diagnosis had strong association with event-free and overall survival (p = 0.01 and 0.003, respectively), with the patients with increased levels having worse survival. Patients with high CA 125 levels at diagnosis who achieved remission showed a significant decrease in CA 125 levels in remission. In conclusion, CA 125 is not only a reliable marker for staging and assessing tumor activity in NHL, elevated levels are also predictive of decreased survival.

Detection of methylated ABL1 promoter in philadelphia-negative myeloproliferative disorders.

Aberrant methylation of tumor-suppressor gene promoter regions may play a causal role in the pre-neoplastic stage of cancer progression. In chronic myeloid leukemia, changes in the methylation status of the CpG-rich islands at several sites in the proximal ABL1 promoter (Pa) on the Philadelphia (Ph)-chromosome have been observed. It remains unclear if the Pa methylation precedes the translocation event (t9;22) that generates the Ph-chromosome or if Pa methylation is a stochastic event in a progenitor cell which will later acquire other mutations, namely t9;22. The present study was conducted to answer two questions: What is the methylation status of Pa in patients with Ph-negative myeloproliferative disorders (MPD)? Can the study of methylation in patients with Ph-negative MPD shed light on the initial events associated with the translocation? To probe CpG methylation, we used two methodologies; site-methylation-sensitive restriction enzyme assay and methylation-specific PCR analysis following modification of genomic DNA by bisulfite. Results showed that 22 of the 97 patients with Ph-negative MPD expressed BCR-ABL transcripts. Seven of the 97 patients possessed methylated Pa, but only 2 of them expressed BCR-ABL transcripts. In some of the patients, Pa methylation was a dynamic event. In conclusion, aberrant methylation in Ph-negative MPD could be an initial event triggering the occurrence of the t9;22 translocation and its clinical expression. These findings may shed light on the pathogenesis and progression of MPD.

Clinical severe hepatic venoocclusive disease during induction treatment of acute monoblastic leukemia managed with defibrotide.

Hepatic venoocclusive disease (VOD) is the most common complication of cytoreductive therapy used for stem cell transplantation, but it is rarely encountered during induction treatment of acute leukemia. We describe a patient in whom severe clinical VOD developed shortly after induction treatment for acute monoblastic leukemia. Administration of intravenous defibrotide for 19 days induced complete resolution of the VOD. Further consolidation treatment was resumed including high-dose cytosine arabinoside without further complications.