Adult acute leukemia

Incidence of myelosuppression in AML is higher compared with that in ALL

Acute myeloid leukemia (AML) and acute lymphocytic leukemia (ALL) are two subtypes of acute leukemia. However, studies investigating the ability of complete blood count (CBC) parameters to distinguish between patients with AML and ALL remain scarce in the literature. The objective of the present study was to compare the parameters of CBC analysis between Chinese patients with AML and ALL and between patients with M3 AML and non-M3 AML. Prognostic factors for overall survival were also estimated, including sex, age, white blood cell count and hemoglobin. The present study included 147 patients, including children and adults, with newly diagnosed acute leukemia. Information on the age, sex, leukemia subtype, initial CBC results and clinical follow-up findings was recorded and compared between the indicated groups using statistical tests of Mann-Whitney U test and χ2 test. Leukopenia (white blood cell count <3.5x109/l), both leukopenia and anemia, both leukopenia and thrombocytopenia and pancytopenia were found to be significantly more frequent among patients with AML compared with that in patients with ALL (P=0.015, 0.016, 0.015 and 0.019, respectively). For patients with ALL, anemia was recognized as a predictor of a favorable outcome (Hazard ratio, 0.185; 95% CI, 0.046-0.747; P=0.018). These findings suggest that normal hematopoiesis is more frequently inhibited in patients with AML compared with that in patients with ALL. Patients with AL with peripheral blood findings indicative of leukopenia, pancytopenia, or both leukopenia and anemia or both leukopenia and thrombocytopenia are more likely to have AML.

Application of image recognition technology in pathological diagnosis of blood smears

Traditional manual blood smear diagnosis methods are time-consuming and prone to errors, often relying heavily on the experience of clinical laboratory analysts for accuracy. As breakthroughs in key technologies such as neural networks and deep learning continue to drive digital transformation in the medical field, image recognition technology is increasingly being leveraged to enhance existing medical processes. In recent years, advancements in computer technology have led to improved efficiency in the identification of blood cells in blood smears through the use of image recognition technology. This paper provides a comprehensive summary of the methods and steps involved in utilizing image recognition algorithms for diagnosing diseases in blood smears, with a focus on malaria and leukemia. Furthermore, it offers a forward-looking research direction for the development of a comprehensive blood cell pathological detection system.

Dental and Periodontal Treatment Need after Dental Clearance Is Not Associated with the Outcome of Induction Therapy in Patients with Acute Leukemia: Results of a Retrospective Pilot Study

This retrospective pilot study aimed to detect whether remaining dental/periodontal treatment need and periodontal inflammation after dental clearance would be associated with the initial therapy outcome of adult patients with acute leukemia undergoing induction chemotherapy. Different parameters were assessed from the patients' records: initial blood parameters, blood parameters during initial chemotherapy, leukemia/therapy related complaints, duration of fever, microbiological findings (blood and urine), as well as patients' survival. Dental treatment need was defined as the presence of at least one carious tooth; periodontal treatment need was determined by the presence of probing depth ≥3.5 mm in at least two sextants. To reflect periodontal inflammation, the periodontal inflamed surface area (PISA) was applied. Thirty-nine patients were included. A dental treatment need of 75% and periodontal treatment need of 76% as well as an average PISA of 153.18 ± 158.09 were found. Only two associations were detected: periodontal treatment need was associated with thrombocyte count after 7 days (p=0.03), and PISA was associated with erythrocyte count three days after induction of therapy (p=0.01). It can be concluded that remaining dental and periodontal treatment need as well as periodontal inflammation after dental clearance is not associated with the outcome of induction therapy in adult patients with acute leukemia.

Scutellaria barbata D. Don (SBD) protects oxygen glucose deprivation/reperfusion-induced injuries of PC12 cells by up-regulating Nrf2

This study aimed to investigate the potential effect of Scutellaria barbata D. Don (SBD) on oxygen glucose deprivation/reperfusion (OGD/R)-injured PC12 cells. PC12 cells were pretreated with various concentrations of 0.1-0.8 mg/ml SBD for indicated times (12-48 h) and then subjected to OGD/R injury. Cell viability, apoptosis and proliferation were detected using MTT assay, flow cytometry, Ki67 staining and western blot. Oxidative damage was assessed by detecting MDA content, SOD activity and GSH levels. The mitochondrial membrane potential (Δψm) was measured by Rh123 staining. Western blot was performed to assess the expression levels of Nrf2 and PI3K/AKT pathway-related proteins. We found that SBD pretreatment promoted cell viability and proliferation but inhibited apoptosis of OGD/R-injured PC12 cells in dosage- and time-dependent manner. Meanwhile, SBD attenuated oxidative damage and restored mitochondria dysfunction, as evidenced by the reduced MDA content, the increased SOD and GSH levels, and the increased Δψm. Furthermore, SBD induced the expression of Nrf2 in a PI3K/AKT-dependent signalling. Knockdown of Nrf2 blocked the protective effects of SBD on PC12 cells. In conclusion, this study demonstrates that SBD pretreatment protects PC12 cells against OGD/R-induced injury. The potential mechanism may be through up-regulating the expression of Nrf2 in a PI3K/AKT-dependent pathway.

The novel three-way variant t(6;17;15)(p21;q21;q22) in acute promyelocytic leukemia with an FLT3-ITD mutation: A case report

Acute promyelocytic leukemia (APL) is characterized by the reciprocal translocation t(15;17)(q22;q21), resulting in the fusion of the promyelocytic leukemia gene at 15q22 with the retinoic acid receptor α at 17q21. Additionally, all patients with APL who have additional chromosome abnormalities (ACA) and gene mutations are resistant to all-trans retinoic acid (ATRA), the drug that causes disease regression specifically in patients with APL globally. The present study describes a case of a 19-year-old female with APL carrying a novel complex variant translocation t(6;17;15)(p21;q21;q22), add(7)(q32) and an FMS-related tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutation. Complete remission was attained following a course of chemotherapy with ATRA and arsenic trioxide. To the best of our knowledge, this is the first report of a novel three-way translocation of 6p21 and a FLT3-ITD mutation involved with APL.

Investigating the microRNA-mRNA regulatory network in acute myeloid leukemia

Acute myeloid leukemia (AML) is a common myelogenous malignancy in adults that is often characterized by disease relapse. The pathophysiological mechanism of AML has not yet been elucidated. The present study aimed to identify the crucial microRNAs (miRNAs/miRs) and target genes in AML, and to uncover the potential oncogenic mechanism of AML. miRNA and mRNA expression-profiling microarray datasets were downloaded from the Gene Expression Omnibus database. Differential expression analysis was performed and a regulatory network between miRNAs and target genes was constructed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were used to predict the biological functions of the differentially expressed genes. Reverse transcription-quantitative polymerase chain reaction analysis was employed to verify the expression levels of miRNAs and target genes in AML patient samples. A total of 86 differentially expressed miRNAs and 468 differentially expressed mRNAs between AML and healthy blood samples were identified. In total, 47 miRNAs and 401 mRNAs were found to be upregulated, and 39 miRNAs and 67 mRNAs were found to be downregulated in AML. A total of 223 miRNA-target genes pairs were subjected to the construction of a regulatory network. Differentially expressed target genes were significantly enriched in the Wnt signaling pathway (hsa04310), melanogenesis (hsa04916) and pathways in cancer (hsa05200). Significantly differentially expressed miRNAs and genes, including hsa-miR-155, hsa-miR-192, annexin A2 (ANXA2), frizzled class receptor 3 (FZD3), and pleomorphic adenoma gene 1 (PLAG1), may serve essential roles in AML oncogenesis. Overall, hsa-miR-155, hsa-miR-192, ANXA2, FZD3 and PLAG1 may be associated with the development of AML via the involvement of the Wnt signaling pathway, melanogenesis and other cancer-associated signaling pathways.

Oral health status in adult patients with newly diagnosed acute leukemia

BACKGROUND

The aim of this cross-sectional study was to evaluate the oral health of adult patients with newly diagnosed acute leukemia.

METHODS

Patients with initially diagnosed acute myeloid (AML) or lymphocytic (ALL) leukemia and a matched healthy control (HC) group were included. The oral investigation comprised inspection of the oral mucosa; the decayed (D), missing (M), and filled (F) teeth (DMF-T) index; and a detailed periodontal status. Subgingival biofilm samples were analyzed (polymerase chain reaction) for the presence of selected potentially periodontal pathogenic bacteria. Statistical analysis was performed using Fisher's exact test, chi-squared test, and Mann-Whitney U test (significance level α = 5%).

RESULTS

Thirty-nine patients with leukemia (AML 26, ALL 13) and 38 HCs were included. Oral mucosal findings were present in 62% of L compared to 0% of HC patients, whereby gingival hyperplasia was the most detected finding. Furthermore, a higher caries prevalence in leukemia patients was shown (D value 3.64 ± 3.98 vs. 0.72 ± 1.72, p < 0.01). The periodontal parameters were poorer in leukemia patients. No substantial differences in microbiological findings of selected bacteria were detected within L group and between L and HC patients.

CONCLUSION

The high prevalence of oral diseases supports the demand of an early and consequent dental treatment of leukemia patients, especially considering subsequent therapy.

An autologous leukemia cell vaccine prevents murine acute leukemia relapse after cytarabine treatment

Acute leukemias with adverse prognostic features carry a high relapse rate without allogeneic stem cell transplantation (allo-SCT). Allo-SCT has a high morbidity and is precluded for many patients because of advanced age or comorbidities. Postremission therapies with reduced toxicities are urgently needed. The murine acute leukemia model C1498 was used to study the efficacy of an intravenously administered vaccine consisting of irradiated leukemia cells loaded with the natural killer T (NKT)-cell agonist α-galactosylceramide (α-GalCer). Prophylactically, the vaccine was highly effective at preventing leukemia development through the downstream activities of activated NKT cells, which were dependent on splenic langerin(+)CD8α(+) dendritic cells and which led to stimulation of antileukemia CD4(+) and CD8(+) T cells. However, hosts with established leukemia received no protective benefit from the vaccine, despite inducing NKT-cell activation. Established leukemia was associated with increases in regulatory T cells and myeloid-derived suppressor cells, and the leukemic cells themselves were highly suppressive in vitro. Although this suppressive environment impaired both effector arms of the immune response, CD4(+) T-cell responses were more severely affected. When cytarabine chemotherapy was administered prior to vaccination, all animals in remission posttherapy were protected against rechallenge with viable leukemia cells.

Confocal backscattering spectroscopy for leukemic and normal blood cell discrimination

Leukemia is the most common pediatric cancer and leading cause of cancer related deaths in children. Improvements in the assessment of leukemic cells have the potential to influence not only the diagnosis of leukemia, but also the risk assessment of patients during the course of the treatment, both of which are important for improving the cure rate for this disease. In this study, we report on the design and performance of a confocal laser based system built to collect backscattered light over a range of 26° at 405, 488, and 633 nm to discriminate leukemic cells from normal red blood cells (RBC) and white blood cells (WBC). The design of the system is based on the spectral differences observed from spectroscopy measurements with a similar system designed with a white light source. Significant differences are observed in the intensity and wavelength dependence of leukemic cells from normal RBC and WBC. Specifically, the distinct light scattering of RBC is due to hemoglobin absorption, allowing for its discrimination from leukemic cells, mononuclear, and polymorphonuclear WBC particularly at certain wavelengths. Meanwhile, the high scattering intensities of polymorphonuclear WBC reflect the intracellular complexity of these cells in comparison to the leukemic or normal lymphocytes. Additionally, the detected light scattering spectra for leukemic cells are consistently steeper in comparison to normal WBC, which we attributed to differences in the fractal organization of intracellular scatterers. Based on our findings, the system has potential applications in the detection and quantification of leukemic cells in blood either in vivo or in vitro, using microfluidic-based systems, for disease monitoring.

Confocal backscattering-based detection of leukemic cells in flowing blood samples

The prognostic value of assessing minimal residual disease (MRD) in leukemia has been established with advancements in flow cytometry and PCR. Nonetheless, these techniques are limited by high equipment costs, complex, and costly cell processing and the need for highly trained personnel. Here, we demonstrate the potential of exploiting differences in the relative intensities of backscattered light at three wavelengths to detect the presence of leukemic cells in samples containing varying mixtures of white blood cells (WBCs) and leukemic cells flowing through microfluidic channels. Using 405, 488, and 633 nm illumination, we identify distinct light scattering intensity distributions for Nalm-6 leukemic cells, normal mononuclear (PBMC) and polymorphonuclear (PMN) white blood cells and red blood cells. We exploit these differences to develop cell classification algorithms, whose performance is evaluated based on simultaneous acquisition of light scattering and fluorescence flow cytometry data. When this algorithm is used prospectively for the analysis of samples consisting of mixtures of PBMCs and leukemic cells, we achieve an average specificity and sensitivity of leukemic cell detection of 99.6 and 45.2%, respectively. When we consider samples that include leukemic cells along with PMNs and PBMCs, which can be acquired using a simple red blood cell lysis step following venipuncture, the specificity and sensitivity of the approach decreases to 91.6 and 39.5%, respectively. On the basis of the performance of these algorithms, we estimate that 42 or 71 μL of blood would be adequate to confirm the presence of leukemia at an 80% power level in samples containing 0.01% leukemia to either PBMCs or PBMCs and PMNs, respectively. Therefore, light scattering-based flow cytometry in a microfluidic platform could provide a low cost, highly portable, minimally invasive approach for detection and monitoring of leukemic patients. This could offer significant improvements especially for pediatric patients and for patients in developing countries.

Acute leukemia presenting with blasts first found in the cerebrospinal fluid but not in the peripheral blood

Acute leukemia presenting with central nervous system (CNS) signs and symptoms is uncommon and prone to be misdiagnosed. Here, we report nine patients with acute leukemia, including five patients with acute lymphoblastic leukemia (ALL) and four patients with acute myeloid leukemia (AML). These patients presented with symptoms suggestive of involvement of multiple cranial nerves, the spinal cord, and meningeal involvement. Moreover, we found that all these patients unexpectedly showed the presence of blasts in the cerebrospinal fluid (CSF) but not in the peripheral blood despite repeated examinations. Bone marrow examination confirmed the presence of acute leukemia in these patients. Seven patients died within 18months of diagnosis and two patients developed stable disease. Our findings show a novel presenting feature of acute leukemia and highlight the importance of CSF cytology in the diagnosis of acute leukemia.

Identification of a novel point mutation in ENT1 that confers resistance to Ara-C in human T cell leukemia CCRF-CEM cells

The genetic basis for the Ara-C resistance of CCRF-CEM Ara-C/8C leukemia cells was investigated. DNA sequencing revealed that these cells expressed an equilibrative nucleoside transporter 1 (ENT1) with a single missense mutation resulting in glycine to arginine replacement (G24R). To test the importance of this residue, additional G24 mutants were created and examined for [3H]-uridine and [3H]-Ara-C uptake. Both a G24E and G24A mutant showed reduced ENT1-dependent activity. An EGFP-tagged G24R ENT1 displayed plasma membrane localization even though it was unable to bind [3H]-NBMPR, an ENT1-specific inhibitor. These results define G24 as critical amino acid for ENT1 nucleoside uptake and suggest that mutations in TM1 may provide a mechanism for Ara-C resistance in CCRF-CEM Ara-C/8C cells.

Pooled analysis of clinical and cytogenetic features in treatment-related and de novo adult acute myeloid leukemia and myelodysplastic syndromes based on a consecutive series of 761 patients analyzed 1976-1993 and on 5098 unselected cases reported in the literature 1974-2001

To ascertain the frequency of treatment-related acute myeloid leukemias and myelodysplastic syndromes (t-AML/t-MDS) in an unselected series, we have identified all adult cases analyzed in our department from 1976 to 1993. Further aims were to compare karyotypic features of t-AML/t-MDS with de novo AML/MDS, in our material as well as in 5098 unselected, cyto- genetically abnormal, published cases, and to analyze associations between type of prior therapy and karyotype. Among our 372 AML and 389 MDS, 47 (13%) were t-AML and 62 (16%) were t-MDS. Clonal abnormalities were significantly more common in t-AML and t-MDS than in de novo disease (68% vs 50%, P < 0.05 and 84% vs 45%, P < 0.001, respectively). Among the available 4230 AML and 1629 MDS (the present series and published cases), 14% were t-AML and 15% were t-MDS. In t-AML/t-MDS, the number of anomalies and the ploidy levels differed significantly from de novo cases, with complex and hypodiploid karyotypes being more common in t-AML/t-MDS. In t-AML, unbalanced changes in general, t(1;3), der(1;7), 3p-, -5, 5q-, -7, 7q-, t(9;11), t(11;19), t(11q23), der(12p), -17, der(17p), -18, and -21 were significantly more frequent than in de novo AML. In t-MDS, -5, -7, 7q-, 13q-, der(17p), and -18 were significantly more common. Type of prior treatment correlated significantly with number of anomalies in t-AML and with ploidy levels in t-AML/t-MDS. The frequencies of several aberrations varied with type of therapy, eg, 5q- was more frequent in radiotherapy-associated t-MDS, monosomy 7 was more common in t-AML and t-MDS after treatment with alkylators, and t(11q23) in t-AML was associated with topoisomerase II inhibitors. Abnormalities significantly more common in de novo disease were +8 as a sole anomaly, balanced changes in general, t(8;21), t(9;22), t(15;17), inv(16), and t(21q22) in AML, and -Y, 5q-, and 20q- as sole anomalies and +8 in MDS. The results emphasize the strong association between previous genotoxic exposure and karyotypic features.

Cell surface antigen and molecular targeting in the treatment of hematologic malignancies

Conventional cytotoxic therapy of hematologic malignancies is often associated with significant morbidity. This morbidity is often due to the lack of specificity for hematopoietic cells. Therefore, the concept of targeted therapy for patients with hematologic malignancies has received attention for many years. The goal of monoclonal antibody therapy is to target specific cell surface antigens on malignant hematopoietic cells, while sparing normal cells and tissues. Currently, monoclonal antibodies are being evaluated for their cytotoxic effects as well as their ability to deliver toxic agents or radiation. Rituximab, a chimeric anti-CD20 antibody, has shown response rates of approximately 50% with minimal toxicity in patients with refractory indolent lymphoma. Campath-1H (anti-CD52) has shown encouraging results in patients previously treated for chronic lymphocytic leukemia, with response rates up to 33%, although with significant toxicity. Anti-CD33 antibodies are being used to deliver cytotoxic agents, such as calicheamicin to patients with acute myeloid leukemia with response rates up to 30%. In addition, anti-CD33 and anti-CD45 antibodies have been used to deliver radiation directly to leukemic cells. (131)I-labeled anti-CD45 antibodies are being studied in combination with conventional preparative regimens in patients receiving bone marrow transplantation. Lastly, the therapeutic agent STI571 (signal transduction inhibitor 571) has demonstrated the capability of targeting specific molecular abnormalities seen in hematologic malignancies. STI571 targets the tyrosine kinase activity of the bcr-abl fusion protein seen in chronic myeloid leukemia. STI571 has induced complete hematologic responses in up to 98% of patients evaluated in clinical trials.

Dose optimization of a doxorubicin prodrug (HMR 1826) in isolated perfused human lungs: low tumor pH promotes prodrug activation by beta-glucuronidase

HMR 1826 (N-[4-beta-Glucuronyl-3-nitrobenzyl-oxycarbonyl]doxorubicin) is a nontoxic glucuronide prodrug from which active doxorubicin is released by beta-glucuronidase. Preclinical studies aimed at dose optimization of HMR 1826, based on intratumoral pharmacokinetics, are important to design clinical studies. Using an isolated perfused human lung model, the uptake of doxorubicin into normal tissue and tumors after perfusion with 133 microg/ml (n = 6), 400 microg/ml (n = 10), and 1200 microg/ml (n = 6) HMR 1826 was compared. Extracellular tissue pH was measured, and enzyme kinetic studies were performed in vitro to investigate the effect of pH on the formation of doxorubicin. Extracellular pH was lower in tumors than in healthy tissue (6.46 +/- 0.35, n = 8 versus 7.30 +/- 0.33, n = 10; p < 0.001). In vitro, beta-glucuronidase activity was 10 times higher at pH 6.0 than at neutral pH. After perfusion with HMR 1826, there was a linear relationship between HMR 1826 concentrations in perfusate and normal lung tissue. After perfusion with 133, 400, and 1200 microg/ml HMR 1826, the final doxorubicin concentrations in normal and tumor tissue were 2.7 +/- 0.9, 11.1 +/- 5.4, and 21.8 +/- 8.4 microg/g (p < 0.05 for all comparisons), and 0.7 +/- 0.3, 8.6 +/- 2.0 microg/g (p < 0.01 versus 133 microg/g), and 8.7 +/- 4.9 microg/g, respectively. This agrees with the enzyme kinetic observations of saturation of beta-glucuronidase at 400 microg/ml HMR 1826 in the acidic environment of the tumor. Therefore, the escalation of the HMR 1826 dose most likely results in higher circulating concentrations than 400 microg/ml but does not increase the uptake of doxorubicin into tumors and, subsequently, antitumor efficacy. The isolated perfused human lung is an excellent model for preclinical investigations aimed at optimization of tissue pharmacokinetics of tumor-selective prodrugs.

Lovastatin induced control of blast cell growth in an elderly patient with acute myeloblastic leukemia

We recently reported that AML cells derived either from cell lines or from patients undergo apoptosis in response to lovastatin, an agent used extensively in the treatment of hypercholesterolemia. The concentration of lovastatin required to achieve this in culture varies from patient to patient, however, the in vitro concentrations required to kill AML cells, can be attained clinically. While in vitro studies assessing responsiveness of leukemic cells to lovastatin were being performed, a 72 year old female presented with relapsed AML. The patient did not desire any further induction therapy. As the patient's cells proved to be sensitive in culture to lovastatin, the patient was offered this drug. In this brief report we describe a case in which there was apparent control of the patient's leukemic blast cells by lovastatin at a dose double the usual recommended dose for hypercholesterolemia. This case illustrates the potential for lovastatin to provide a novel means of controlling leukemic cell growth in AML patients.

Patients with de novo acute myeloid leukaemia and complex karyotype aberrations show a poor prognosis despite intensive treatment: a study of 90 patients

The clinical significance of complex chromosome aberrations for adults with acute myeloid leukaemia (AML) was assessed in 920 patients with de novo AML who were karyotyped and treated within the German AML Cooperative Group (AMLCG) trials. Complex chromosome aberrations were defined as three or more numerical and/or structural chromosome aberrations excluding translocations t(8;21)(q22;q22), t(15;17)(q22;q11-q12) and inv(16)(p13q22). Complex chromosome anomalies were detected in 10% of all cases with a significantly higher incidence in patients > or = 60 years of age (17.8% vs. 7.8%, P < 0.0001). Clinical follow-up data were available for 90 patients. Forty-five patients were < 60 years of age and were randomly assigned to double induction therapy with either TAD-TAD [thioguanine, daunorubicin, cytosine arabinoside (AraC)] or TAD-HAM (high-dose AraC, mitoxantrone). Twenty-one patients achieved complete remission (CR) (47%), 20 patients (44%) were non-responders and 9% of patients died during aplasia (early death). The median overall survival (OS) was 7 months and the OS rate at 3 years was 12%. Patients receiving TAD-HAM showed a significantly higher CR rate than patients receiving TAD-TAD (56% vs. 23%, P = 0.04). Median event-free survival was less than 1 month in the TAD-TAD group and 2 months in the TAD-HAM group, respectively (P = 0.04), with a median OS of 4.5 months vs. 7.6 months (P = 0.13) and an OS after 3 years of 7.6% vs. 19.6%. Forty-five patients were > or = 60 years of age: 28 of these patient were treated for induction using one or two TAD courses and 17 cases received TAD-HAM with an age-adjusted reduction of the AraC dose. The CR rate was 44%, 38% were non-responders and 18% experienced early death. The median OS was 8 months and the OS rate at 3 years was 6%. In conclusion, complex chromosome aberrations in de novo AML predicted a dismal outcome, even when patients were treated with intensive chemotherapy. Patients under the age of 60 years with complex aberrant karyotypes may benefit from HAM treatment during induction. However, long-term survival rates are low and alternative treatment strategies for remission induction and consolidation are urgently needed.

Lovastatin induces a pronounced differentiation response in acute myeloid leukemias

We recently identified HMG-CoA reductase, the rate-limiting enzyme of the mevalonate pathway, as a potential therapeutic target of various retinoic acid responsive cancers. Lovastatin, a competitive inhibitor of HMG-CoA reductase, induced a retinoic acid-like differentiation response followed by extensive apoptosis in neuroblastoma cell lines at relatively low concentrations (<20 microM) of this agent. More recently, we demonstrated that acute myeloid leukemias but not acute lymphocytic leukemias also displayed increased sensitivity to lovastatin-induced apoptosis. In this study, we examined the ability of lovastatin to induce differentiation of acute myeloid leukemic cells and to evaluate the role differentiation may hold in the anti-leukemic properties of this agent. Increased expression of the leukocyte integrins CD11b and CD18 as well as down-regulation of the anti-apoptotic gene bcl-2 are associated with late stage differentiation of the myeloid lineage and retinoic acid induced maturation of acute myeloid leukemic cells. Lovastatin exposure induced increased expression of CD11b and CD18 markers similar to retinoic acid treatment. Following 24 hrs exposure to 20 microM lovastatin, all 7 acute myeloid leukemia cell lines tested showed a decrease in bcl-2 mRNA expression while only 1/5 acute lymphocytic leukemia cell lines showed a similar response. A role for bcl-2 in the apoptotic response of acute myeloid leukemia cells to lovastatin was demonstrated as exogenous constitutive expression of bcl-2 in the AML-5 cell line inhibited apoptosis in a time and dose dependent manner. Thus, lovastatin exposure of acute myeloid leukemia cells induced a differentiation response that may contribute to the therapeutic potential of this agent in the treatment of this disease.

T-lymphocyte production of macrophage inflammatory protein-1α is critical to the recruitment of CD8+ T cells to the liver, lung, and spleen during graft-versus-host disease

To investigate the mechanism by which macrophage inflammatory protein-1α (MIP-1α) affects graft-versus-host disease (GVHD), the expression and function of MIP-1α in 2 murine models of GVHD were evaluated. In irradiated class I and class II disparate recipients, the expression of messenger RNA (mRNA) and protein for MIP-1α was significantly increased in GVHD target organs after transfer of allogeneic lymphocytes compared to syngeneic lymphocytes. When lymphocytes unable to make MIP-1α were transferred, there was a decrease in the production of MIP-1α in the liver, lung, and spleen of bm1 (B6.C-H2bm1/By) and bm12 (B6.C-H2bm12/KhEg) recipients compared to the transfer of wild-type splenocytes. At day 6 there was a 4-fold decrease in the number of transferred CD8+ T cells in the lung and approximately a 2-fold decrease in the number of CD8+ T cells in the liver and spleen in bm1 recipients after transfer of MIP-1α–deficient (MIP-1α−/−) splenocytes compared to wild-type (MIP-1α+/+) splenocytes. These differences persisted for 13 days after splenocyte transfer. In contrast, the number of donor CD4+ T cells found in the liver and lung was significantly increased after the transfer of MIP-1α−/− compared to wild-type splenocytes in bm12 recipients from day 6 through day 10. Thus, the transfer of allogeneic T cells was associated with the enhanced expression of MIP-1α in both a class I and class II mismatch setting. However, the increased expression only led to enhanced recruitment of CD8+, but not CD4+, donor T cells. Production of MIP-1α by donor T cells is important in the occurrence of GVHD and functions in a tissue-dependent fashion.

T-lymphocyte production of macrophage inflammatory protein-1α is critical to the recruitment of CD8+ T cells to the liver, lung, and spleen during graft-versus-host disease

To investigate the mechanism by which macrophage inflammatory protein-1α (MIP-1α) affects graft-versus-host disease (GVHD), the expression and function of MIP-1α in 2 murine models of GVHD were evaluated. In irradiated class I and class II disparate recipients, the expression of messenger RNA (mRNA) and protein for MIP-1α was significantly increased in GVHD target organs after transfer of allogeneic lymphocytes compared to syngeneic lymphocytes. When lymphocytes unable to make MIP-1α were transferred, there was a decrease in the production of MIP-1α in the liver, lung, and spleen of bm1 (B6.C-H2bm1/By) and bm12 (B6.C-H2bm12/KhEg) recipients compared to the transfer of wild-type splenocytes. At day 6 there was a 4-fold decrease in the number of transferred CD8+ T cells in the lung and approximately a 2-fold decrease in the number of CD8+ T cells in the liver and spleen in bm1 recipients after transfer of MIP-1α–deficient (MIP-1α−/−) splenocytes compared to wild-type (MIP-1α+/+) splenocytes. These differences persisted for 13 days after splenocyte transfer. In contrast, the number of donor CD4+ T cells found in the liver and lung was significantly increased after the transfer of MIP-1α−/− compared to wild-type splenocytes in bm12 recipients from day 6 through day 10. Thus, the transfer of allogeneic T cells was associated with the enhanced expression of MIP-1α in both a class I and class II mismatch setting. However, the increased expression only led to enhanced recruitment of CD8+, but not CD4+, donor T cells. Production of MIP-1α by donor T cells is important in the occurrence of GVHD and functions in a tissue-dependent fashion.

Increased Sensitivity of Acute Myeloid Leukemias to Lovastatin-Induced Apoptosis: A Potential Therapeutic Approach

We recently demonstrated that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme of de novo cholesterol synthesis, was a potential mediator of the biological effects of retinoic acid on human neuroblastoma cells. The HMG-CoA reductase inhibitor, lovastatin, which is used extensively in the treatment of hypercholesterolemia, induced a potent apoptotic response in human neuroblastoma cells. This apoptotic response was triggered at lower concentrations and occurred more rapidly than had been previously reported in other tumor-derived cell lines, including breast and prostate carcinomas. Because of the increased sensitivity of neuroblastoma cells to lovastatin-induced apoptosis, we examined the effect of this agent on a variety of tumor cells, including leukemic cell lines and primary patient samples. Based on a variety of cytotoxicity and apoptosis assays, the 6 acute lymphocytic leukemia cell lines tested displayed a weak apoptotic response to lovastatin. In contrast, the majority of the acute myeloid leukemic cell lines (6/7) and primary cell cultures (13/22) showed significant sensitivity to lovastatin-induced apoptosis, similar to the neuroblastoma cell response. Of significance, in the acute myeloid leukemia, but not the acute lymphocytic leukemia cell lines, lovastatin-induced cytotoxicity was pronounced even at the physiological relevant concentrations of this agent. Therefore, our study suggests the evaluation of HMG-CoA reductase inhibitors as a therapeutic approach in the treatment of acute myeloid leukemia.

Increased Sensitivity of Acute Myeloid Leukemias to Lovastatin-Induced Apoptosis: A Potential Therapeutic Approach

We recently demonstrated that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme of de novo cholesterol synthesis, was a potential mediator of the biological effects of retinoic acid on human neuroblastoma cells. The HMG-CoA reductase inhibitor, lovastatin, which is used extensively in the treatment of hypercholesterolemia, induced a potent apoptotic response in human neuroblastoma cells. This apoptotic response was triggered at lower concentrations and occurred more rapidly than had been previously reported in other tumor-derived cell lines, including breast and prostate carcinomas. Because of the increased sensitivity of neuroblastoma cells to lovastatin-induced apoptosis, we examined the effect of this agent on a variety of tumor cells, including leukemic cell lines and primary patient samples. Based on a variety of cytotoxicity and apoptosis assays, the 6 acute lymphocytic leukemia cell lines tested displayed a weak apoptotic response to lovastatin. In contrast, the majority of the acute myeloid leukemic cell lines (6/7) and primary cell cultures (13/22) showed significant sensitivity to lovastatin-induced apoptosis, similar to the neuroblastoma cell response. Of significance, in the acute myeloid leukemia, but not the acute lymphocytic leukemia cell lines, lovastatin-induced cytotoxicity was pronounced even at the physiological relevant concentrations of this agent. Therefore, our study suggests the evaluation of HMG-CoA reductase inhibitors as a therapeutic approach in the treatment of acute myeloid leukemia.