Evolution of the global internal dynamics of a living cell nucleus during interphase.

Progress in cellular biology based on fluorescent microscopy techniques, shows that the spatial organization of the nucleus is dynamic. This dynamic is very complex and involves a multitude of phenomena that occur on very different time and size scales. Using an original light scattering experimental device, we investigated the global internal dynamics of the nucleus of a living cell according to the phases of the cell cycle. This dynamic presents two different and independent kinds of relaxation that are well separated in time and specific to the phase of the cell cycle.

Tumor necrosis factor as an autocrine growth factor for neuroblastoma.

Recombinant tumor necrosis factor (TNF) stimulates the proliferation of two neuroblastoma cell lines, SKNFI and SKNBE, in both serum-free medium and fetal calf serum-supplemented medium but has no effect in medium without insulin. This effect is very similar with TNF doses ranging from 5 to 500 ng/ml but depends on the duration of treatment; when cells are treated for 168 h with TNF, the maximal index of proliferation is observed between 120 and 144 h of treatment. The two neuroblastoma cell lines express type A and type B TNF receptors and contain TNF protein; however, TNF is undetectable in culture supernatants. Treatment of the two neuroblastoma cell lines with a rabbit polyclonal antibody to TNF for 96 h fully inhibits [3H]thymidine incorporation; less than 5% viable cells are left in the samples after treatment. A combination of two monoclonal antibodies against type A and type B TNF receptors also inhibits over 85% of the [3H]thymidine incorporation by the two cell lines after 96 h of treatment; the use of a single antibody has a partial effect, suggesting that both receptors are functional on the neuroblastoma cell lines. Taken together, these results show that TNF is an autocrine growth factor for the two neuroblastoma cell lines SKNFI and SKNBE. The results described above have been confirmed on two other neuroblastoma cell lines, IRM32 and CLB-PE.

Serum level of interleukin 6 as a prognosis factor in metastatic renal cell carcinoma.

Interleukin (IL) 6 was measured in the serum of 138 patients with metastatic renal carcinoma before the initiation of IL-2 treatment. IL-6 was detectable in 66 patients with renal cancer (48%) and in only 8 of 70 normal adults (11%). Serum C reactive protein (CRP) and IL-6 levels are correlated, suggesting that IL-6 is involved in CRP increase in these patients. The interval between diagnosis of the primary tumor and metastasis was shorter in patients with a detectable serum IL-6 and/or serum CRP level greater than 50 mg/liter. Serum IL-6 and CRP levels were higher in subgroups of patients previously defined as having a poor life expectancy according to the Eastern Cooperative Oncology Group criteria. Pretreatment concentrations of IL-6 and CRP were higher in patients who experienced progressive disease after IL-2 treatment. Patients with detectable IL-6 had a shorter survival from the beginning of IL-2 treatment than patients without circulating IL-6 (median, 8 versus 16 months). Similarly, the median survival from the beginning of IL-2 therapy of patients with CRP levels greater than 50 mg/liter was 6 months, compared to 16 months in those with CRP levels below this threshold. None of the 21 patients with serum IL-6 concentrations greater than 300 pg/ml achieved response to any of the three IL-2 regimens. This subgroup has a median survival of 5 months after IL-2 treatment and consisted of 15% of the patients in our series. These results indicate that serum IL-6 and CRP levels are adverse prognosis factors in patients with metastatic renal cell carcinoma. Serum IL-6 level could help in the selection or stratification of the patients in future IL-2 trials.

Towards the molecular elucidation of congenital myasthenic syndromes: identification of mutations in MuSK.

Congenital myasthenic syndromes (CMS) are rare genetic diseases affecting the neuromuscular junction (NMJ) and characterized by a dysfunction of the neurotransmission. They are heterogeneous at the pathophysiological level and can be classified in three categories according to their origin: presynaptic, synaptic or postsynaptic. The strategy for the diagnosis and characterization of CMS relies on the clinic, EMG, muscle biopsy, identification of mutations in genes known to be responsible for CMS and the demonstration that the gene mutations are the cause of the disease by using experimental approaches. As an example of such strategy, we report briefly here the characterization of the first case of a human neuromuscular transmission dysfunction due to mutations in the gene encoding a postsynaptic molecule, the muscle-specific receptor tyrosine kinase (MuSK). Gene analysis identified two heteroallelic mutations, a frameshift mutation (c.220insC) and a missense mutation (V790M). The muscle biopsy showed marked pre- and postsynaptic structural abnormalities of the neuromuscular junction as well as a severe decrease in acetylcholine receptor epsilon-subunit and MuSK expression. In vitro and in vivo expression experiments were performed using mutant MuSK reproducing the human mutations. The results obtained strongly suggested that the missense mutation, in the presence of a null mutation on the other allele, was responsible for the severe synaptic changes observed in the patient and, hence, is causing the disease. However the molecular origin of a large number of CMS is still unknown. There are hundreds of molecules known to be present at the NMJ and mutations in the genes coding for these synaptic molecules are likely to be responsible for a neuromuscular block.

Fetal liver cell transplantation in various murine models.

Allogeneic fetal liver cell transplantation has been shown to be able to reconstitute lymphopoietic systems of mice when these systems are defective or destroyed. Lethally irradiated mice or mice with inherited severe combined immunodeficiency disease (SCID) were grafted with 14 days gestation allogeneic fetal liver cells, then subjected to a follow-up for the immune tolerance to the donor and the normal or subnormal immune reconstitution allowing prevention of diabetes in NOD mice or cure of leukemia in AKR mice and of immunodeficiency in SCID mice. Briefly, when normal CBA mice were lethally irradiated and then grafted with allogeneic fetal liver cells from Balb/c mice, a specific immune tolerance was induced to donor skin grafts. Unrelated skin grafts were rejected and a response to antigens was observed in these chimeras. However, despite the capacity to develop hyperacute rejection of skin allografts, following hyperimmunization, these chimeric mice did not produce anti-H2 cytotoxic antibodies. In SCID mice (CB17), the immune reconstitution occurred when mice were grafted with allogeneic (C57/B16) as well as with syngeneic fetal liver cells. Human cells were found in SCID mice following implantation of human fetal liver and thymus cells. When NOD mice were irradiated, then grafted with allogeneic fetal liver cells, a large part of donor cells were found in NOD recipients, correlating with a low incidence of diabetes. Leukemic AKR mice grafted with allogeneic fetal liver cells had virtually no leukemia relapse, suggesting a strong graft-versus-leukemia effect following such a transplant.

Internal dynamics of a living cell nucleus investigated by dynamic light scattering.

Recent progresses in cellular biology have shown that the nucleus of a living cell is a structured integration of many functional domains with a complex spatial organization. This organization, as well as molecular and biochemical processes, is time regulated. In the past years many investigations have been performed using fluorescent microscopy techniques to study the internal dynamics of the nucleus of a living cell. These investigations, however, have never focussed on the global internal dynamics of the nucleus, which is still unknown. In this article we present an original light scattering experimental device that we built to investigate this dynamics during biological processes. By means of this experimental set-up, we investigated the global dynamics of the nucleus of a living cell treated with a DNA replication inhibitor. This dynamics presents different and independent kinds of relaxation well separated in time that vary as a function of the cell cycle phases.

Sialadenitis in nonobese diabetic mice: transfer into syngeneic healthy neonates by splenic T lymphocytes.

In the present study, we showed that both male and female nonobese diabetic (NOD) mice simultaneously develop frequent lymphocyte infiltrations in salivary submandibular glands (sialadenitis), very similar to those reported in the salivary glands of patients with Sjögren syndrome. These lesions were observed only in mice with pancreas exhibiting insulitis. The incidence of sialadenitis increased with the severity of insulitis. At the initial stage, small focal infiltrates were predominantly located around blood vessels. In older animals, inflammatory cells surrounded blood vessels and ducts. Most of the infiltrating cells proved to be L3T4+, whereas Lyt-2+ cells were comparatively few. Autoantibodies against duct epithelial cells were shown, but the degree of tissue invasion was not related to the existence of such antibodies. Antinuclear antibodies were also observed. These salivary gland infiltrates could be transferred in vivo to NOD neonates of both sexes by splenic T lymphocytes as well as by total spleen cells. These results suggest that sialadenitis in NOD mice is T cell mediated and may be related to insulitis.

IL-10 inhibits alloreactive cytotoxic T lymphocyte generation in vivo.

In this report, we present evidence that the CTL response directed against MHC Class I allo-determinants can be inhibited as a result of IL-10 expression in vivo. The presence of localized IL-10 secretion at the site of allogeneic tumor cell challenge resulted in marked inhibition of the CTL response and allowed growth of the tumor in the allogeneic host. Using purified CD4+ T cells from mice immunized in the presence or absence of IL-10, we have shown that the loss of alloreactivity as a consequence of IL-10 expression results from the inhibition of CD4+ T cell function. The expression of either IL-2 or IFN-gamma with IL-10 locally at the time of allogeneic cell challenge completely restored CTL alloreactivity, suggesting that the action of IL-10 could be bypassed by providing helper T lymphocyte-derived cytokines of the Th1 type at the site of immunization. Inhibition of alloreactivity by IL-10 was observed using either purified macrophages or dendritic cells as APC in an in vitro assay. Thus, the expression of IL-10 following antigenic challenge (such as that observed in Th2-like immune responses) may profoundly limit the ability for generating functional CTL in vivo.

Insulin prevents adoptive cell transfer of diabetes in the autoimmune non-obese diabetic mouse.

Early intensive insulin treatment is thought to improve subsequent Beta-cell function in Type 1 (insulin-dependent) diabetic patients. Prophylactic insulin administration also reduced diabetes incidence in diabetes-prone animals. To study the mechanisms by which these effects occur, we tested the ability of insulin therapy in the model of non-obese-diabetic mice, to prevent the penetration of committed T cells into the islets and subsequent Beta-cell destruction. Sublethally irradiated non-obese-diabetic males of 8 weeks of age were adoptively transferred with splenocytes from diabetic donors and treated with the maximum tolerable dosage of fast-acting insulin (0.5 U, twice daily) until 30 days after cell transfer. Diabetes incidence was compared to control animals injected with the same concentration of insulin diluent. After one month of treatment, the cumulative diabetes frequency was significantly less within the insulin-treated group (4 of 15, 26.6%) than in the control group (15 of 18, 83.3%; p less than 0.01). Pancreatic histological analysis of insulin-treated animals revealed a lower severity of insulitis and Beta-cell necrosis and a higher percentage of normal islets (46.6 +/- 10% vs 2.3 +/- 2%, p less than 0.01), including five (33%) mice with no lesions. Immunoperoxydase staining of pancreatic sections indicated similar insulin and ganglioside staining of Beta cells from insulin-treated mice and control animals. Insulin-treated mice had comparable pancreatic insulin content to normal mice. Flow cytometry analysis of spleen cell populations indicated that insulin increased the number of Thy1,2+ and Lyt-2+ T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumor induction and tissue atrophy in mice lacking E2F-1.

The retinoblastoma tumor suppressor protein (pRB) is a transcriptional repressor that regulates gene expression by physically associating with transcription factors such as E2F family members. Although pRB and its upstream regulators are commonly mutated in human cancer, the physiological role of the pRB-E2F pathway is unknown. To address the function of E2F-1 and pRB/E2F-1 complexes in vivo, we have produced mice homozygous for a nonfunctional E2F-1 allele. Mice lacking E2F-1 are viable and fertile, yet experience testicular atrophy and exocrine gland dysplasia. Surprisingly, mice lacking E2F-1 develop a broad and unusual spectrum of tumors. Although overexpression of E2F-1 in tissue culture cells can stimulate cell proliferation and be oncogenic, loss of E2F-1 in mice results in tumorigenesis, demonstrating that E2F-1 also functions as a tumor suppressor.

Mitogen-activated protein kinase-mediated Fas apoptotic signaling pathway.

Ligation of the cell surface receptor Fas/APO-1 (CD95) by its specific ligand or by anti-Fas antibodies rapidly induces apoptosis in susceptible cells. To characterize the molecular events involved in Fas-induced apoptosis, we examined the contribution of two subgroups of the mitogen-activated protein (MAP) kinase family, the Jun kinases or stress-activated protein kinases (JNKs/SAPKs) and the extracellular signal-regulated kinases (ERKs), in a Fas-sensitive neuroblastoma cell line. Here we show that both JNK and ERK protein kinases were activated upon Fas crosslinking through a Ras-dependent mechanism. Interference with either the JNK or ERK pathway by ectopic expression of dominant-interfering mutant proteins blocked Fas-mediated apoptosis. ERK activation was transient and associated with induced expression of the Fas receptor. In contrast, JNK activation was sustained and correlated with the onset of apoptosis. These data indicate that the ERK and the JNK groups of MAP kinases cooperate in the induction of cell death by Fas. Inhibition of Fas killing by an interleukin 1beta-converting enzyme (ICE)-like protease inhibitor peptide did not modify Fas-induced JNK activation upon Fas ligation. In contrast, changes in Bcl-2 level due to expression of sense and antisense vectors influenced the sensitivity to Fas killing and Fas-induced JNK activation.

Expression of integrin receptors on 45 clinical neuroblastoma specimens.

Immunohistological expression of integrins has been analyzed on 45 neuroblastoma specimens representative of the different clinical and histological forms of the tumor. None of the specimens expressed the alpha 5 chain of the integrins. The beta 1 chain was expressed on all specimens, the alpha 1 chain on 44 specimens and the alpha 3 chain on 42; the 4 specimens which lacked alpha 1 or alpha 3 were stage-4 neuroblastomas. The alpha 2 chain was expressed on 18 specimens, and the alpha 6 chain on 17; 15 reacted with both. Their reactivity was related to the maturation of the tumor rather than the stage of the disease: they were expressed on low-grade, well-differentiated specimens; stage 3-4 neuroblastoma specimens analyzed at diagnosis were negative, but usually expressed both chains when analyzed after in vivo differentiation by chemotherapy. alpha v reacted with 18 specimens and beta 3 with 12, without strict relation with the stage of the disease and/or its degree of differentiation; 9 well-differentiated specimens expressed the beta 4 chain; only 4 well-differentiated specimens expressed the alpha 4 chain. The 4 specimens which lacked alpha 1-beta 1 or alpha 3-beta 1 expression had n-myc amplification, whereas those which expressed either alpha 4, beta 4, beta 3 or alpha v had no amplification. Furthermore, the expression of the 3 heterodimers alpha 4-beta 1, alpha v-beta 3 and alpha 6-beta 4 was essentially observed on primary tumors which developed in the mediastinum. The expression of alpha 2-beta 1 and alpha 6-beta 1 was observed on both n-myc-positive and -negative specimens. beta 1 and alpha 3 were diffusely expressed on all counterparts of these tumors, from undifferentiated neuroblasts to ganglion and Schwann cells. The alpha 1 chain reacted with undifferentiated and intermediate neuroblasts as well as with Schwann cells, but ganglion cells were negative. alpha 2 and alpha 6 chains were negative on undifferentiated neuroblasts, variably expressed on intermediate neuroblasts, and restricted to Schwann cells in ganglioneuroma. The expression of alpha 4 and beta 4 was restricted to Schwann cells. alpha v and beta 3 occasionally reacted with undifferentiated and intermediate neuroblasts; alpha v was strongly positive on Schwann cells but negative on ganglion cells, whereas beta 3 was positive on both neuronal and non-neuronal populations.

Expression of P-glycoprotein restricted to normal cells in neuroblastoma biopsies.

Immunohistological detection of P-glycoprotein (P-gp) with monoclonal antibody C219 was performed on serial sections of 37 neuroblastoma specimens representative of the different forms of the disease, from stage 1 ganglioneuroma to stage 4 neuroblastoma. Malignant cells, irrespective of their degree of maturation varying from neuroblasts to ganglion cells, were negative on all specimens. The expression of P-glycoprotein was detected in nine specimens, but it was restricted to normal cells within the tumour. In four specimens, C219 reacted with normal infiltrating cells in the stroma (i.e. monocytes, histiocytes or fibroblasts) representing 5 to 10% of the total population within the section; in three specimens, the residual adrenal gland was strongly positive, and in two ganglioneuromas, a weak reactivity of C219 was observed on a few satellite cells and schwann cells. Three of 15 biopsies obtained at diagnosis contained normal P-gp positive cells: two were classified as stage 1 ganglioneuromas; one was a typical stage 4 composite tumours with positive histiocytes and fibroblasts in the well-differentiated counterpart. Six of 22 biopsies obtained after patients had received our current protocol of chemotherapy contained normal P-gp positive cells: five were partially differentiated and necrotic under the effect of chemotherapy; only one positive specimen was classified as undifferentiated neuroblastoma. Among negative specimens from previously treated patients, one was obtained from a patient in relapse after high-dose chemotherapy and ABMT, two were obtained from patients who had not responded to induction therapy, and six from patients in partial remission after induction therapy. The clinical evolution was very similar in both groups of patients with P-gp negative or positive biopsies. These findings suggest that the quantitative assessment of MDR RNA by northern blotting on fresh homogenates is likely to overestimate its expression on neuroblastoma cells, and that the mechanism of chemoresistance in widespread neuroblastoma is less likely to be associated with P-gp expression.

Expression of leucocyte adhesion molecules on 66 clinical neuroblastoma specimens.

LFA-3, ICAM-1, HLA.ABC and HLA.DR expression was analyzed on 66 neuroblastoma specimens. HLA.ABC was expressed on 26 specimens, HLA.DR on 2, LFA-3 on 20 and ICAM-1 on 10. HLA.ABC and LFA-3 were positive on ganglioneuroblastoma or ganglioneuroma, but they were negative on neuroblastoma, independently of the clinical staging; HLA.ABC and LFA-3 were induced in vivo by chemotherapy in parallel with tumoral cell differentiation, in both the primary and the metastases. The expression of ICAM-1 was restricted to 5 of the 10 low-grade stage-1 or stage-2 specimens, 1 stage-3 specimen, and the primary tumors of 2 patients with stage-4 disease, analyzed hence at diagnosis and after chemotherapy (4 specimens); metastatic cells obtained in 1 of these patients were negative. HLA.ABC and LFA-3 expressed on both mycN-negative and -positive specimens, whereas ICAM-1 was restricted to MYCN-negative specimens. LFA-3 diffusely stained partially differentiated neuroblasts, Schwann cells and ganglion cells. The expression of HLA.ABC on differentiated neuroblasts varied from one sample to another and within the same tumor; Schwann cells were strongly positive, but ganglion cells were negative. In positive samples, ICAM-1 was expressed on differentiated neuroblasts and Schwann cells, but negative on ganglion cells; however, most of the differentiated tumors were ICAM-1-negative, suggesting ICAM-1 induction by unknown local signal. The 4 markers were negative on undifferentiated neuroblasts. The distribution of these 4 markers on clinical specimens was in agreement with their reactivity on fetal tissues, as well as with results obtained on neuroblastoma cell lines before and after in vitro treatment with IFN-gamma.