BCR-ABL-mediated inhibition of apoptosis with delay of G2/M transition after DNA damage: a mechanism of resistance to multiple anticancer agents

A critical determinant of the efficacy of antineoplastic therapy is the response of malignant cells to DNA damage induced by anticancer agents. The p53 tumor-suppressor gene is a critical component of two distinct cellular responses to DNA damage, the induction of a reversible arrest at the G1/S cell cycle checkpoint, and the activation of apoptosis, a genetic program of autonomous cell death. Expression of the BCR-ABL chimeric gene produced by a balanced translocation in chronic myeloid leukemia, confers resistance to multiple genotoxic anticancer agents. BCR-ABL expression inhibits the apoptotic response to DNA damage without altering either the p53-dependent WAF1/CIP1-mediated G1 arrest or DNA repair. BCR-ABL-mediated inhibition of DNA damage-induced apoptosis is associated with a prolongation of cell cycle arrest at the G2/M restriction point; the delay of G2/M transition may allow time to repair and complete DNA replication and chromosomal segregation, thereby preventing a mitotic catastrophe. The inherent resistance of human cancers to genotoxic agents may result not only by the loss or inactivation of the wild-type p53 gene, but also by genetic alterations such as BCR-ABL that can delay G2/M transition after DNA damage.     

Autologous transplantation of bone marrow purged in vitro with anti-CD7- (WT1-) ricin A immunotoxin in T-cell lymphoblastic leukemia and lymphoma

Seven patients with high-risk acute T-cell lymphoblastic leukemia (T- ALL) and six with T cell lymphoma (T-LL) were treated with autologous bone marrow transplantation (ABMT) after in vitro purging of their bone marrow with WT1 (CD7)-ricin A-chain immunotoxin. CD7 expression on the tumor cells showed large variations between the individual patients and was highly related to the specific cytotoxicity of WT1-ricin A. Incubation of bone marrow with up to 10(-8)mol/L WT1-ricin A in the presence of 6 mmol/L NH4Cl did not compromise the growth potential of the hematopoietic progenitors CFU-GM, CFU-GEMM, and BFU-E. Hematologic engraftment (greater than 10(9) leukocytes/L) occurred within a normal time period (median, 17 days). Seven patients are alive and in complete remission (CR) at 48+, 44+, 40+, 26+, 11+, 7+, and 6+ months after ABMT. Four patients relapsed within 6 months after ABMT. Two of them had the lowest CD7 expression on their tumor cells, the other two were transplanted in CR2 and CR3. Two patients died from transplantation related infections. The immunologic reconstitution was delayed, although the numbers of T cells reached normal levels within 1 month. The number of CD7+ cells remained low up to 1 year after transplantation. The T4/T8-ratio was decreased for at least 6 months. The T-cell response to mitogens recovered to normal levels after 1 year. This study shows that ABMT with WT1-ricin A purged bone marrow in high-risk T-cell malignancies results in a complete hematopoietic and a delayed immunologic reconstitution. The actuarial relapse free survival is 61% at 3 years.     

A gene for a myosin peptide is disrupted by the inv(16)(p13q22) in acute nonlymphocytic leukemia M4Eo

Chromosome 16 aberrations are well known in acute nonlymphocytic leukemia (ANLL). The most frequent chromosome 16 aberration in ANLL subtype M4Eo is the inv(16)(p13q22). Recently, we showed that in 5 inv(16) patients with ANLL M4Eo the short arm breakpoints are clustered within a 14-kb genomic EcoRI fragment. We report here the identification of a gene situated in the 14-kb fragment. The gene, which codes for a myosin peptide, is disrupted by the inversion of chromosome 16 in the 5 patients. To the best of our knowledge, this is the first report of a myosin gene disrupted in leukemia.     

Detection of monosomy 7 and trisomy 8 in myeloid neoplasia: a comparison of banding and fluorescence in situ hybridization

Fluorescence in situ hybridization (FISH) is a powerful tool for detection of numerical and structural chromosomal aberrations. We have compared conventional banding techniques and FISH for the detection of monosomy 7 (-7) and trisomy 8 (+8) in 89 patients with myeloid malignancies. Of these patients, 21 had -7, 30 had +8, four had both, and 34 had no aberrations or aberrations other than -7 or +8 as assessed by banding techniques. Sequential samples were available in 23 patients. Alphoid DNA probes specific for chromosomes no. 7 and 8 were used for FISH. As controls, 10 normal bone marrow (BM) samples were hybridized with the chromosomes no. 7 and 8 probes, and in addition all tumor samples were hybridized with a chromosome no. 1 specific probe. The cut-off value for -7 was 18% one-spot cells, and for +8 was 3% three-spot cells. FISH analysis of 44 samples with -7 or +8, and at least 10 metaphases evaluated, showed that the proportions of aberrant metaphase cells mirrored the interphase clone sizes. Most samples with nonclonal metaphase aberrations, including those with only a few metaphases, had increased numbers of aberrant interphase cells: 20% to 80% for -7, and 3% to 43% for +8. Interphase cytogenetics of the 34 samples without -7 or +8 did not show significant cell populations with -7 or +8. In four patients, -7 or +8 could not be confirmed by FISH due to additional structural aberrations, marker chromosomes, or wrongly interpreted banding results. As FISH will be used more and more in cytogenetic diagnosis, clinical follow-up, and therapy monitoring, it will be necessary to standardize FISH procedures and supplement the Standing Committee on Human Cytogenetic Nomenclature (ISCN) definitions of a clone with criteria specifically for in situ hybridization.     

Gastroprotective effect of the aqueous leaf extract of Guiera senegalensis in Albino rats

ObjectiveTo evaluate the effect of aqueous leaf extract of Guiera senegalensis (G. senegalensis) on gastric mucosal damage using different ulcer models.MethodsConsidering the above claims, the present study was undertaken to validate the gastroprotective potential of the aqueous leaf extract of this plant against ethanol, water immersion and Aspirin induced ulcer models.ResultsThe leaf extract (50, 100 and 200 mg/kg, p.o.) significantly (P<0.05) decreased the ulcer index in all assays used.ConclusionsThe results obtained, provide strong evidence of antiulcer activity of the leaf extract of G. senegalensis and support the traditional uses of the plant for the treatment of ulcer.     

Increased hepatocyte CYP2E1 expression in a rat nutritional model of hepatic steatosis with inflammation

BACKGROUND & AIMS: Nonalcoholic steatohepatitis is morphologically identical to alcoholic hepatitis and has multiple etiologic associations and an unknown pathogenesis. The present study used a rat nutritional model of hepatic steatosis with inflammation to test the hypothesis that induction of the alcohol-inducible hepatic cytochrome P450 (CYP) 2E1 is associated with production of steatohepatitis. METHODS: Rats received a diet devoid of methionine-choline. CYP2E1 protein was detected in liver sections by immunohistochemistry and in hepatic microsomal fractions by immunoblotting; CYP2E1 activity was detected by N-demethylation of N,N-dimethylnltrosamine (NDMA). CYP2E1 messenger RNA was analyzed by Northern blotting and slot blot hybridization. RESULTS: After 4 weeks of methionine-choline devoid diet, macrovesicular steatosis and an inflammatory infiltrate were prominent in hepatic acinar zone 3. CYP2E1 immunostaining was increased and had a more extensive acinar distribution corresponding to that of the steatosis. Microsomal CYP2E1 protein, NDMA activity, and hepatic CYP2E1 messenger RNA levels were all correspondingly increased. CONCLUSIONS: CYP2E1 is induced, partly at a pretranslational level, in this experimental form of steatohepatitis. The finding of biochemical and histological similarities between this nutritional model of hepatic steatosis with inflammation and alcoholic hepatitis indicates possible clues to common pathogenetic mechanisms. The relevance of this finding to human nonalcoholic steatohepatitis remains uncertain and requires further investigation of human liver specimens. (Gastroenterology 1996 Dec;111(6):1645-53)     

Monocytes stimulate fibroblastoid bone marrow stromal cells to produce multilineage hematopoietic growth factors

In previous studies we have found that monocytes produce soluble factors that stimulate human umbilical vein endothelial cells to produce granulocyte-macrophage colony-stimulating activity (CSA), burst- promoting activity (BPA), and megakaryocyte colony-stimulating activity (Meg-CSA) as well as factors that stimulate T lymphocytes and neonatal fibroblasts to produce CSA. To test the hypothesis that monocytes would similarly stimulate the production of hematopoietic growth factors by autologous bone marrow stromal cells, multiply-passaged adherent fibroblastoid cells derived from the bone marrow of normal volunteers were exposed to conditioned media prepared by incubating autologous peripheral blood monocytes in complete medium for three days. When conditioned media from stromal cells incubated in monocyte-conditioned medium were compared with those of stromal cells cultured in the absence of monocyte-conditioned medium, BPA was increased fourfold and CSA was increased more than 30-fold. We conclude that mononuclear phagocytes recruit stromal cells of the marrow to produce multilineage growth factors in vitro. We suggest that these monocyte-derived recruiting activities may play an important role in orchestration of hematopoietic growth factor production by cells of the marrow microenvironment.     

Allogeneic bone marrow transplantation with a fixed low number of T cells in the marrow graft [see comments]

Despite prophylaxis with immunosuppressive drugs, severe acute graft- versus-host disease (GVHD) remains a major cause of morbidity and mortality in patients transplanted with unmodified bone marrow (BM) grafts from HLA-identical siblings. Although T-cell depletion of the BM graft has evolved as the most effective method to prevent severe acute GVHD, this beneficial effect is counterbalanced by an increased rate of graft failure and relapse of the disease. To find an approach to T-cell depletion that may avoid these extreme risks, we gave BM recipients a fixed low number of 1 x 10(5) donor T cells per kilogram of recipient's body weight in the graft. This corresponds with 99% T-cell depletion and is achieved by the addition of T cells to the graft that was previously depleted of T cells. A total of 70 patients with hematologic malignancies or aplastic anemia, including 40 patients with standard- risk leukemias, received BM grafts, depleted of T cells according to this approach, from HLA-identical siblings. The preparative regimen consisted of cyclophosphamide and total body irradiation. The patients also received a short course of cyclosporine posttransplant. Graft failure did not occur. Acute GVHD, only grade I or II, was seen in 70% of the patients and was limited to the skin in all patients. Chronic GVHD occurred in 31% of the patients and, with the exception of 1 patient, was limited to the skin as well. Relapse occurred in 3 of 40 (8%) patients with standard-risk leukemias, resulting in a projected survival at 5 years of 80%. Patients with standard-risk diseases had a procedure-related mortality of 11%. Quality of life, determined 1 year after BM transplant, was good in almost all patients with standard-risk diseases. Thus, this approach of T-cell depletion may be an approach that avoids the development of severe acute and chronic GVHD without damaging the function or antileukemic effect of the graft and that has a low transplant-related morbidity and mortality.     

Modelling and costing the consequences of using an ACE inhibitor to slow the progression of renal failure in type I diabetic patients

Antihypertensive drugs slow the progressive decline in renal function seen in patients with insulin-dependent diabetes and nephropathy. In a recent study, the ACE inhibitor captopril protected against this deterioration in renal function. We developed an economic model to analyse the cost impact of ACE inhibitor treatment on progression to endstage renal failure (ESRF) in diabetic patients over 4 years. Two scenarios were compared: one describing the progression of a cohort of 1000 patients receiving 25 mg captopril three times daily, and the other for an equivalent cohort without such prophylactic treatment. Previously published data were used to estimate the transition rates for each stage from the onset of renal failure until death. All direct costs were discounted by an annual rate of 6%, and were subjected to sensitivity analysis. The discounted cost saving of ACE inhibitor treatment for a cohort of 1000 patients was estimated as 0.95 million pounds over 4 years. Under sensitivity analysis, these results were very robust to variations in the costs of ESRF treatment. Prophylactic treatment with ACE inhibitors was predicted to provide substantial increases in life expectancy and reduction in the incidence of ESRF, while also providing significant economic savings.