beta2-adrenergic receptor-selective agonist clenbuterol prevents Fas-induced liver apoptosis and death in mice

Stimulation of the cAMP-signaling pathway modulates apoptosis in several cell types and inhibits Jo2-mediated apoptosis in cultured rat hepatocytes. No information is yet available as to whether the hepatic beta2-adrenergic receptor (AR) expression level, including beta2-AR-dependent adenylyl cyclase activation, modulates hepatocyte sensitivity to apoptosis in vivo or whether this sensitivity can be modified by beta2-AR ligands. We have examined this using C57BL/6 mice, in which hepatic beta2-AR densities are low, and transgenic F28 mice, which overexpress beta2-ARs and have elevated basal liver adenylyl cyclase activity. The F28 mice were resistant to Jo2-induced liver apoptosis and death. The beta-AR antagonist propranolol sensitized the F28 livers to Jo2. In normal mice clenbuterol, a beta2-AR-specific agonist, considerably reduced Jo2-induced liver apoptosis and death; salbutamol, another beta2-AR-selective agonist, also reduced Jo2-induced apoptosis and retarded death but with less efficacy than clenbuterol; and propranolol blocked the protective effect of clenbuterol. This indicates that the expression level of functional beta2-ARs modulates Fas-regulated liver apoptosis and that this apoptosis can be inhibited in vivo by giving beta2-AR agonists. This may well form the basis for a new therapeutic approach to diseases involving abnormal apoptosis.

Dysembryoplastic neuroepithelial tumors: nonspecific histological forms -- a study of 40 cases

OBJECTIVE

To demonstrate that DNTs include a large morphological spectrum of tumors that cannot be histologically distinguished from conventional categories of gliomas.

METHODS

All tumors from patients who underwent epilepsy surgery in Sainte-Anne hospital (Paris) that histologically resembled gliomas and did not conform to current histological criteria for DNTs or gangliogliomas were entered in the study.

RESULTS

According to the WHO histological classification, the 40 tumors resembled: pilocytic astrocytomas (4 cases), astrocytomas (16 cases), anaplastic astrocytoma (1 case), oligodendrogliomas (10 cases), oligo-astrocytomas (8 cases) or anaplastic oligo-astrocytomas (1 case). However foci of cortical dysplasia could be observed in 47% of the cases. Clinical presentation and imaging features were strikingly similar to that observed in typical DNTs. Although surgical removal was incomplete in 28% of the cases and none of the patients underwent chemo or radiotherapy, none of the tumors recurred (mean follow-up: 7 years). Moreover, serial preoperative imaging in 26 patients (mean follow-up: 4.5 years) demonstrated that these lesions were perfectly stable.

CONCLUSIONS

Whatever the histological appearance of a glial tumor, the diagnosis of DNT must be considered when all the following criteria are associated: (1) partial seizures, with or without secondary generalization, beginning before the age 20 years, (2) no neurological deficit or stable congenital deficit, (3) cortical topography of the lesion as better demonstrated by MRI and (4) no mass effect on imaging.

Proteasomes regulate erythropoietin receptor and signal transducer and activator of transcription 5 (STAT5) activation. Possible involvement of the ubiquitinated Cis protein

Cis is an Src homology 2 domain-containing protein, which binds to the erythropoietin receptor and decreases erythropoietin-stimulated cell proliferation. We show that Cis associates with the second tyrosine residue of the intracellular domain of the erythropoietin receptor (Tyr401). Two forms of Cis with molecular masses of 32 and 37 kDa were detected, and we demonstrate that the 37-kDa protein resulted from post-translational modifications of the 32-kDa form. Anti-ubiquitin antibodies recognized the 37-kDa form of Cis and the proteasome inhibitors N-acetyl-leucyl-leucyl-norleucinal and lactacystin inhibited its degradation, showing that the 37-kDa form of Cis is a ubiquitinated protein, which seems to be rapidly degraded by the proteasome. In erythropoietin-stimulated UT-7 cells, the activation of the erythropoietin receptor and signal transducer and activator of transcription 5 (STAT5) was transient and returned to basal levels after 30-60 min of erythropoietin stimulation. In contrast, these proteins remained strongly phosphorylated, and STAT5 remained activated for at least 120 min in the presence of proteasome inhibitors. These experiments demonstrate that the proteasomes are involved in the down-regulation of the erythropoietin receptor activation signals. Because the proteasome inhibitors induced the accumulation of both the ubiquitinated form of Cis and the Cis-erythropoietin receptor complexes, our results suggest that the ubiquitinated form of Cis could be involved in the proteasome-mediated inactivation of the erythropoietin receptor.

A sequence of the CIS gene promoter interacts preferentially with two associated STAT5A dimers: a distinct biochemical difference between STAT5A and STAT5B

Two distinct genes encode the closely related signal transducer and activator of transcription proteins STAT5A and STAT5B. The molecular mechanisms of gene regulation by STAT5 and, particularly, the requirement for both STAT5 isoforms are still undetermined. Only a few STAT5 target genes, among them the CIS (cytokine-inducible SH2-containing protein) gene, have been identified. We cloned the human CIS gene and studied the human CIS gene promoter. This promoter contains four STAT binding elements organized in two pairs. By electrophoretic mobility shift assay studies using nuclear extracts of UT7 cells stimulated with erythropoietin, we showed that these four sequences bound to STAT5-containing complexes that exhibited different patterns and affinities: the three upstream STAT binding sequences bound to two distinct STAT5-containing complexes (C0 and C1) and the downstream STAT box bound only to the slower-migrating C1 band. Using nuclear extracts from COS-7 cells transfected with expression vectors for the prolactin receptor, STAT5A, and/or STAT5B, we showed that the C1 complex was composed of a STAT5 tetramer and was dependent on the presence of STAT5A. STAT5B lacked this property and bound with a stronger affinity than did STAT5A to the four STAT sequences as a homodimer (C0 complex). This distinct biochemical difference between STAT5A and STAT5B was confirmed with purified activated STAT5 recombinant proteins. Moreover, we showed that the presence on the same side of the DNA helix of a second STAT sequence increased STAT5 binding and that only half of the palindromic STAT binding sequence was sufficient for the formation of a STAT5 tetramer. Again, STAT5A was essential for this cooperative tetrameric association. This property distinguishes STAT5A from STAT5B and could be essential to explain the transcriptional regulation diversity of STAT5.

[Radiation-induced DNA fragmentation evaluated by anti-poly(ADP-ribose)immunolabeling in CHO cells. Standardization with pulsed-field electrophoresis]

The poly (ADP-ribose) polymerase is an ubiquitous nuclear protein capable of binding specifically to DNA strand breaks. It synthesizes ADP-ribose polymers proportionally to DNA breaks. The actual method of reference to determine DNA double strand breaks is pulsed-field gel electrophoresis, but this requires many cells. It thus appeared of interest to use poly (ADP-ribos)ylation to follow and estimate gamma-ray-induced DNA fragmentation at the level of isolated cells after gamma-irradiation in chinese hamster ovary cells (CHO-K1). The results obtained by the immunolabelling technique of ADP-ribose polymers were compared to those obtained by pulsed-field gel electrophoresis. They show that poly (ADP-ribos)ylation reflects the occurrence of radiation-induced DNA strand breaks. A clear relationship exists between the amount of ADP-ribose polymers detected and DNA double strand breaks after gamma-irradiation.

Bcl-2 targeted overexpression into the erythroid lineage of transgenic mice delays but does not prevent the apoptosis of erythropoietin-deprived erythroid progenitors

Erythropoietin (Epo) is known to control the erythroid developmental program through various biologic activities including maintenance of viability, cell proliferation, and/or cell maturation. In vitro experiments showed massive apoptosis in cultures of Epo-deprived colony-forming unit-erythroid (CFU-E) progenitors, demonstrating the Epo requirement of late-stage erythroid progenitors for survival. Based on these data, a model has been proposed whereby from CFU-E to proerythroblast stages, Epo acts rather as a survival factor than a proliferating factor. To investigate the relationship between Epo dependence and apoptotic mechanisms, we generated transgenic mice expressing the antiapoptotic human bcl-2 gene product in erythroid progenitors. Transgenic animals developed without any evidence of erythropoietic disorders. In vitro studies showed that overexpression of bcl-2 in erythroid progenitors delayed, but did not prevent the loss of CFU-E from Epo-deprivation. By measuring burst-forming unit-erythroid (BFU-E) and CFU-E-derived colonies, an enhanced sensitivity to low levels of Epo was demonstrated in adult bone marrow of transgenic mice with respect to nontransgenic animals. No spontaneous erythroid colonies were, however, observed in vitro in the absence of the cytokine, indicating that overexpression of bcl-2 is not sufficient to induce by itself a complete erythroid differentiation. Taken together, our data indicate that targeted erythroid overexpression of bcl-2 fails to alter the normal erythropoietic development in vivo and that erythroid progenitors remain strictly dependent on Epo for their survival.

Oligodendrogliomas. Part I: Patterns of growth, histological diagnosis, clinical and imaging correlations: a study of 153 cases

The present study has attempted to demonstrate that the morphological spectrum of oligodendrogliomas includes tumors which are traditionally misinterpreted as 'diffuse fibrillary astrocytoma'. We have shown that these tumors are in fact made of isolated neoplastic oligodendrocytes which are entrapped in a fibrillary background composed of axons and fibrillary reactive gliosis. Analysis in a series of 153 'pure' supratentorial oligodendrogliomas composed of 'classical' or pseudo 'diffuse fibrillary oligodendrogliomas' diagnosed by imaging-based serial stereotactic biopsies showed that 2/3 of the tumors were exclusively made of isolated tumor cells (ITCs) (structure type III) and that only 1/3 of them exhibited both ITCs and solid tumor tissue components (structure type II). The tumor tissue destroys the brain parenchyma and contains new formed microblood vessels whereas ITCs do not destroy the parenchyma and are not associated with microangiogenesis. These fundamentally opposite morphological characteristics were reflected by the following findings: 1) contrast enhancement was observed in 64% of structure type II but was never seen in structure type III oligodendrogliomas. 2) a neurological deficit occurred in 57% of structure type II but in only 8% of structure type III oligodendrogliomas. 3) using the new grading system described in the companion paper to this study, we found that the biological behavior of oligodendrogliomas was also closely related to the patterns of tumor growth. From a synthesis of data gathered in this study it is suggested that emergence of microangiogenesis within a tumor which at first grows slowly with a structure type III pattern is a crucial event toward more aggressive behavior.

Oligodendrogliomas. Part II: A new grading system based on morphological and imaging criteria

This second part of our study of 'pure' oligodendrogliomas focuses on survival data analysis. In order to identify potentially useful prognostic factors and to assess the effectiveness of a new grading system, the 79 patients in the previously analyzed series for whom adequate follow-up could be obtained (52%) were entered in the present analysis. Statistical analysis demonstrated that contrast enhancement and endothelial hyperplasia had powerful and similar influence on survival. Median survival with and without contrast enhancement were: 3 versus 11 years, and with or without endothelial hyperplasia were: 3.5 versus 11 years. Conversely, the degree of nuclear atypia and presence or absence of mitosis or necrosis were not correlated with survival. These findings allowed us to devise a simple grading system which discriminates two malignancy grades as follows: absence of endothelial hyperplasia and of contrast enhancement = Grade A, presence of endothelial hyperplasia and/or of contrast enhancement = Grade B. Of the 79 oligodendrogliomas in this study, 59 tumors were categorized as grade A and 20 as grade B. Median survival were: 11 years in grade A and 3.5 years in grade B. Five-year and 8-year survival rates were: 89% and 60% in grade A and: 33% and 15% in grade B. Double blind grading between two independent observers was concordant in 96% of the cases. Application of this simple efficient and reproducible grading scheme should permit reliable comparison of retrospective or prospective therapeutic data emanating from various institutions.

Dysembryoplastic neuroepithelial tumors located in the caudate nucleus area: report of four cases

OBJECTIVE AND IMPORTANCE

Dysembryoplastic neuroepithelial tumors (DNTs) histologically resemble gliomas but behave as stable lesions. These tumors initially were considered to be located exclusively within the supratentorial cortex. The four reported cases demonstrate that DNTs may also arise in the area of the caudate nuclei. Moreover, the peculiar topography of these lesions, which suggests a derivation from the subependymal plate, is in accordance with the putative origin of DNTs from secondary germinal layers.

CLINICAL PRESENTATION

The patients experienced partial seizures (two patients), generalized seizures (one patient), or headaches (one patient). All patients were young (17-26 yr) at the onset of symptoms, and all had normal results from their neurological examinations.

INTERVENTION

All lesions demonstrated a pseudocystic appearance on computed tomographic scans, were hypointense on T1-weighted magnetic resonance imaging scans, hyperintense on T2-weighted magnetic resonance imaging scans, and did not show contrast enhancement. The four tumors similarly lined the left or right caudate nuclei and expanded within the homolateral ventricle (three patients) or both lateral ventricles (one patient). In one patient, the tumor also involved the adjacent paraolfactory cortex.

CONCLUSION

In all patients, stereotactic biopsies helped to identify a specific glioneuronal element of DNTs. None of the tumors was operated on. Radiotherapy was performed in only one patient. A long pre- and/or postbiopsy imaging follow-up, which was available in two nontreated patients (3 yr and 16 yr), demonstrated the perfect stability of the lesion. The occurrence of DNTs in this peculiar location needs to be considered to avoid misidentification as "ordinary" gliomas and prevent useless aggressive treatment.

Erythropoietin-induced erythroid differentiation of the human erythroleukemia cell line TF-1 correlates with impaired STAT5 activation

The TF-1 cell line has been established from a patient with erythroleukemia. While various cytokines induce TF-1 cell proliferation, erythropoietin (Epo) only sustains the short-term growth of these cells and induces their differentiation along the erythroid lineage. A truncated Epo receptor (EpoR) is overexpressed in these cells. The truncation removed the 96 C-terminal amino acids, including seven tyrosine residues. An additional single mutation at position +3 of Tyr344 led to the replacement of leucine 347 by proline. Stimulation by Epo induced an impaired activation of the STAT5 transcription factor in these cells. The same defect in STAT5 activation was found in the murine FDCP-1 cell line transfected with a chimeric EpoR containing the abnormal TF-1 EpoR cytoplasmic domain. Infection of TF-1 cells with a retrovirus containing a normal murine EpoR was able to restore both Epo-induced STAT5 activity and cellular proliferation. In contrast, Epo-induced differentiation was reduced strongly in infected TF-1ER cells. These results suggest that Epo-induced differentiation correlates with impaired Epo-induced STAT5 activation.

Bcl-2 protects from lethal hepatic apoptosis induced by an anti-Fas antibody in mice

Fas is an apoptosis-signalling cell surface antigen that has been shown to trigger cell death upon specific ligand or antibody binding. Treatment of mice with an anti-Fas antibody causes fulminant hepatic failure due to massive apoptosis. To test a putative protective effect of the anti-apoptotic Bcl-2 protein, transgenic mice were generated to express the human bcl-2 gene product in hepatocytes. Early onset of massive hepatic apoptosis leading to death was observed in all nontransgenic mice treated with an anti-Fas antibody. By contrast, hepatic apoptosis was delayed and dramatically reduced in transgenic animals, yielding a 93% survival rate. These results demonstrate that Bcl-2 is able to protect from in vivo Fas-mediated cytotoxicity, and could be of significance for preventing fulminant hepatic failure due to viral hepatitis in humans.

Isolation of new oncogenic forms of the murine c-fms gene

The c-fms gene encodes the receptor for the macrophage colony-stimulating factor, which plays a key role in the proliferation and differentiation of cells of the myelomonocytic lineage. In order to study the effects of overexpression of the macrophage colony-stimulating factor receptor in hematopoietic cells, a Harvey sarcoma virus-derived retroviral vector containing the murine c-fms cDNA was pseudotyped with Friend murine leukemia virus and inoculated into newborn DBA/2 mice. This viral complex induced monoclonal or oligoclonal leukemias with a shorter latency than that for Friend murine leukemia virus alone. Unexpectedly, 60% of the integrated fms proviruses had deletions at the 5' end of the c-fms gene. Sequence analysis of seven mutant proviruses indicated that the deletions always included the c-fms ligand binding domain and either occurred within the c-fms sequences, leaving the fms open reading frame unchanged, or joined VL30 sequences located at the 5' end of the parental retroviral vector to internal c-fms sequences, resulting in truncated fms proteins devoid of the canonical signal peptide. In contrast to all tyrosine kinase receptors transduced in retroviruses, no helper gag- or env-derived sequences were fused to the rearranged fms sequences. Viral supernatants isolated from hematopoietic tumors with viruses with deletions were able to transform NIH 3T3 cells as efficiently as parental fms virus, indicating that deletions resulted in constitutive activation of the c-fms gene. These oncogenic variants differ from those transduced in the Suzan McDonough strain of feline sarcoma viruses (L. Donner, L. A. Fedele, C. F. Garon, S. J. Anderson, and C. J. Sherr, J. Virol. 41:489-500, 1982). The high rate of c-fms rearrangement and its relevance in the occurrence of hematopoietic tumors are discussed.

Constitutive activation of a variant of the env-mpl oncogene product by disulfide-linked homodimerization

The myeloproliferative leukemia retrovirus (MPLV) has the v-mpl cellular sequences transduced in frame with the deleted and rearranged Friend murine leukemia virus env gene. The resulting env-mpl fusion oncogene is responsible for an acute myeloproliferative disorder induced in mice by MPLV. v-mpl is a truncated form of the c-mpl gene which encodes the receptor for thrombopoietin. We investigated the contribution of the Env-Mpl extracellular domain in the constitutive activation of this truncated cytokine receptor and found that the rearrangement of the env sequences in the env-mpl fusion gene was not required for oncogenicity. A pathogenic variant, DEL3MPLV, was generated, which differs from MPLV by the deletions of 22 amino acids of the Env signal peptide, all of the mature Env sequences, and 18 N-terminal amino acids of the v-Mpl extracellular domain. The resulting del3-mpl oncogene product conserves in its extracellular region the first 12 amino acids of the Env signal sequence including a cysteine residue, and 25 amino acids of the v-Mpl. We show here that a mutation converting this cysteine to a glycine completely abolishes del3-mpl oncogenicity and that the del3-mpl oncogene product is constitutively activated by disulfide-linked homodimerization.

Characterization of mpl cytoplasmic domain sequences required for myeloproliferative leukemia virus pathogenicity

v-mpl is a truncated form of a receptor-like chain which belongs to the cytokine receptor superfamily. This sequence has been transduced in the myeloproliferative leukemia virus as an env-mpl fusion gene responsible for an acute myeloproliferative disorder in mice. We constructed a series of viral mutants in the mpl sequence. Analysis of their oncogenic potential in vivo indicated that a critical 69-amino-acid-long cytoplasmic domain of v-Mpl is required for myoproliferative leukemia virus pathogenicity. We also developed an in vitro assay and showed that expression of the env-mpl gene confers growth factor independence to murine as well as to human hematopoietic growth factor-dependent cell lines. These findings strongly suggest that v-Mpl delivers a constitutive proliferative signal through a limited region of its cytoplasmic domain.

Isolation of a Friend recombinant polytropic virus with a T-cell-restricted leukemogenicity

Hematopoietic malignant cells of various types were isolated from ICFW mice inoculated as newborn or adult with F-MuLV and grafted into recipient mice. After repeated in vivo cell transplants, several recombinant polytropic viruses (also termed MCF or dualtropic viruses) were isolated from tumors by limiting dilution. Two virus isolates designated RA1-17 and EA1-17 were recovered from the spleen and the omentum, respectively, of the same grafted animal. When inoculated into newborn mice, RA1-17 induced erythroblastosis similar to that induced by other Friend recombinant polytropic viruses. Remarkably, EA1-17 induced T-cell leukemia after a short latency. To our knowledge, this is the first description of a polytropic recombinant virus with a T-cell tropism isolated after inoculation of F-MuLV.

Rearrangements of the Pim-1, c-myc, and p53 genes in Friend helper virus-induced mouse erythroleukemias

The Friend helper leukemia virus (F-MuLV) induces in mice leukemias of the erythroid, lymphoid, and myeloblastic lineages. Erythroleukemic cell DNAs were examined for genetic alterations at loci described as common proviral integration regions in MuLV-induced myeloid or lymphoid leukemias or in Friend complex-induced erythroleukemias. No alteration of the Fim-1, Fim-2, Fim-3, pvt-1, and Spi-1 loci were detected in 17 erythroleukemias, p53 gene rearrangement was observed in 6 (30%) erythroleukemias and was always associated with a loss of the germ line allele. Interestingly, genetic alterations were also detected at two loci, c-myc and Pim-1, previously described as common provirus integration regions in T lymphoid leukemias. Rearrangements of these two genes were often associated with p53 gene alteration within the same tumor.

Carotid surgery under cervical block anesthesia. A simple method of heart and brain protection in high risk patients

Between January 1, 1985, and December 15, 1987, 60 patients underwent surgery for carotid lesions under local cervical block anesthesia. Sixty-seven reconstruction procedures were performed including 64 endarterectomies and 3 vein bypasses. During the same 3 year period, 938 other reconstruction procedures were carried out under general anesthesia for a total of 1005 procedures. These 60 patients, who accounted for 6.7% of our indications, were selected for surgery under local anesthesia because they were at high risk for cardiac and neurologic complications. As far as staging is concerned, this subgroup of patients included: 14 asymptomatic cases (stage 0), i.e., 21%; 44 transient ischemic attacks (stage I), i.e., 66%; 2 progressive stroke (stage II), i.e., 3%; 7 patients with neurologic sequels (stage III), i.e., 10%. In all 79% of the patients were symptomatic. The asymptomatic patients all presented bilateral tight stenosis sometimes with thrombosis of the contralateral carotid. The technique of local anesthesia and endarterectomy were classic: closing with a bougie to calibrate the lumen, systematic intraoperative arteriography and immediate correction of technical failures (2 times); no death occurred among the patients in stages 0, 1 and II; 1 early asymptomatic occlusion that was not corrected was noted; in one case, a ligation of the carotid was necessary after technical failure, without consequences; one death occurred in stage III after intracerebral hemorrhage. On the basis of our experience local cervical block anesthesia appears to be a simple and reliable method of ensuring intraoperative diagnosis of cerebral ischemia. It eliminates all intraoperative cerebral complications secondary to ischemia and allows a better understanding of the physiopathologic mechanisms underlying perioperative neurologic complications. The absence of neurologic and cardiac complications in this series of very high risk patients enables us to extend eligibility for surgery to include patients with unstable cardiac and cerebral disease.

[Palliative treatment of neoplastic jaundice by a percutaneous transhepatic endoprosthesis. Apropos of 73 cases]

Seventy three patients with malignant obstruction of the extrahepatic bile ducts were submitted to palliative drainage through percutaneous transhepatic endoprosthesis (P.T.E.). Complications occurred within the first month following the procedure in 13 patients (18%) and 8 of them died (10%). Cholangitis was the main complication resulting, from dysfunction of the endoprosthesis due to an incorrect placement of the stent in most cases. On the other hand, not any significant vascular complication such as previously reported following P.T.E., was encountered in our series. Late complications are mainly due to endoprosthesis obstruction (5 cases) or dislodgement (2 cases). The mortality rate within the first month following P.T.E. is 19%, resulting from either a complication of the procedure (11%) or the underlying disease (8%). The mean survival of these 73 patients, is 4, 7 months. When considering only the 59 patients who are alive one month following the procedure, the mean survival (post-operative deaths excluded) is 6 months. According to our experience P.T.E. remains a valuable palliative procedure when other endoscopic or surgical methods either have failed or cannot be resorted to provided a correct placement of the stent allowing for a good bile drainage can be achieved. Thus P.T.E. is able to provide in many cases the same long-term survival as palliative surgery, allowing the patients to resume their normal daily activity.

MPLV: a retrovirus complex inducing an acute myeloproliferative leukemic disorder in adult mice

A novel murine retrovirus complex was derived from the in vivo passage of a molecularly cloned Friend ecotropic helper virus. The virus isolate, myeloproliferative leukemia virus (MPLV), causes an acute (2-3 weeks) and generalized myeloproliferative disorder in adult mice. All strains of mice examined, including the C57BL/6J strain, developed the acute syndrome. This syndrome is characterized by a rapid hepatosplenomegaly, no thymus or lymph node involvement, granulocytosis, thrombocytosis, and erythroblastosis leading to polycythemia. The most prominent feature at the terminal phase of the disease is a granulocytic hyperplasia. The MPLV isolate replicates in vitro on NIH 3T3 fibroblasts but does not induce foci of transformed cells. Thus, MPLV exhibits unique biological properties that distinguish it either from the Friend virus complexes or from acutely transforming sarcomatogenic murine retrovirus which also induced a rapid splenomegaly.