BTG1, a member of a new family of antiproliferative genes

The BTG1 gene locus has been shown to be involved in a t(8;12)(q24;q22) chromosomal translocation in a case of B-cell chronic lymphocytic leukemia. We report here the cloning and sequencing of the human BTG1 cDNA and establish the genomic organization of this gene. The full-length cDNA isolated from a lymphoblastoid cell line contains an open reading frame of 171 amino acids. BTG1 expression is maximal in the G0/G1 phases of the cell cycle and is down-regulated when cells progress throughout G1. Furthermore, transfection experiments of NIH3T3 cells indicate that BTG1 negatively regulates cell proliferation. The BTG1 open reading frame is 60% homologous to PC3, an immediate early gene induced by nerve growth factor in rat PC12 cells. Sequence and Northern blot analyses indicate that BTG1 and PC3 are not cognate genes. We then postulate that these two genes are the first members of a new family of antiproliferative genes.

Mediators of change in physical activity following an intervention in primary care: PACE

BACKGROUND

The current study evaluated the construct validity of a physical activity intervention in primary care by testing whether the intervention changed hypothesized mediators and whether changes in the mediators were associated with behavior change.

METHODS

Matched physician offices were nonrandomly assigned to intervention or control. Apparently healthy, sedentary, adult patients (N = 255) were recruited from physician offices. The intervention was brief, behaviorally based counseling by physicians, plus a telephone follow-up 2 weeks later. Assessments of physical activity and mediators were collected at baseline and at 4- to 6-week follow-up. Hypothesized mediators were processes of change, self-efficacy, and social support for exercise.

RESULTS

Patients who were counseled improved significantly more than those in the control group on behavioral and cognitive processes of change. Other changes in mediators were nonsignificant. Behavioral processes of change and self-efficacy made significant contributions to the multiple regression model explaining self-report and objective measures of physical activity.

CONCLUSIONS

The intervention affected some of the targeted mediators of physical activity change. Two of three mediator variables were associated with changes in physical activity regardless of experimental condition and other variables. The construct validity of the intervention was partially supported.

Comparison of anti-fading agents used in fluorescence microscopy: image analysis and laser confocal microscopy study

To ascertain the ability of commercial and home-made anti-fading media to reduce the decrease of fluorescein isothiocyanate (FITC) fluorescence, we studied the bleaching characteristics of FITC-stained Reh 6 cells mounted in buffered glycerol and in anti-fading media. We measured the intensity of fluorescence over time with a confocal laser scanning microscope and a standard epifluorescence microscope coupled to an image analysis system. Most of the anti-fading media effectively retard fading but each has drawbacks. Better results were obtained with media containing p-phenylenediamine (solutions in buffered glycerol, Vectashield, Fluorstop). However, Mowiol, Slowfade, n-propyl gallate (20 g/liter) were also effective in retarding fading. Most of them, except Mowiol, reduced fluorescence intensity. We concluded that the choice of anti-fading medium would depend on the desired results: a slower decay of fluorescence despite an initial quenching of fluorescence or a lower retardant effect with no decrease in initial fluorescence intensity. Moreover, the combination of Mowiol with another anti-fading medium may be a useful compromise when a strong retardant effect is required without marked quenching of the initial fluorescence.

Double immunocytochemical labeling of cell and tissue samples with monoclonal anti-bromodeoxyuridine

We describe a new monoclonal antibody (designated Bu20a) against bromodeoxyuridine (BrdU). This antibody was selected by screening against human tissues using the APAAP technique, and shows no crossreactivity with normal nuclei. It stains BrdU incorporated into the nuclei of a wide range of cell types, including human tonsil lymphoid cells, normal mouse tissues, and human tumors growing in nude mice. A double-labeling technique is described using this antibody in which cell smears or tissue sections are first labeled by an immunoperoxidase procedure for a cellular antigen (e.g., mouse or human histocompatibility class II antigen, T-lymphocyte antigen, keratin) and BrdU is then detected by indirect immunofluorescence. This procedure, which was applied to a variety of human and animal cells and tissues, is of wide potential value in analyzing the phenotype of S-phase cells and in co-localizing antigen expression and BrdU incorporation in tissue sections.

The Australian Vietnam Veterans Health Study: III. psychological health of Australian Vietnam veterans and its relationship to combat

BACKGROUND

Self-reported psychiatric status of Australian Vietnam war veterans was determined 20-25 years after the war and its relation to combat was investigated.

METHOD

A simple random sample of Australian Army Vietnam veterans was interviewed nationally using standardized interviews and self-completion tests to assess the prevalence of lifetime and current psychiatric illness and its relationship to combat. Army records were used to extract data on the cohort for use in regression-based adjustment for non-response.

RESULTS

The conditions mainly affecting the Australian veterans were alcohol abuse or dependence, post-traumatic stress disorder, somatization disorder were significantly related to combat exposure but not with posting to a combat unit. Less than half of the current one-month diagnoses were related to combat, possibly because of low power conferred by the relative rarity of these conditions.

CONCLUSIONS

The results confirm a range of psychological problems in former warriors may linger 20 or more years from their war exposure and may be directly affected by exposure to war trauma.

Intensive and sequential combination chemotherapy for aggressive malignant lymphomas (protocol LNH-80)

Ninety-seven patients with aggressive malignant lymphoma (ML) were treated with an intensive and sequential chemotherapy (protocol LNH-80). There were 42 patients with intermediate grade ML, 53 patients with high-grade ML, and two patients with true histiocytic ML. Most of the patients were in advanced stage: 21 stage III and 61 stage IV. The LNH-80 protocol schedule comprised three phases: (1) induction with three courses of an intensified CHOP-Bleo (cyclophosphamide, doxorubicin, vindesine, methylprednisolone, and bleomycin); (2) consolidation with cytarabine, followed by high-dose methotrexate and folinic acid rescue, then asparaginase; and (3) final intensification with two courses of CVAP-Bleo (cyclophosphamide, teniposide, cytarabine, methylprednisolone, and bleomycin). CNS prophylaxis included one injection of methotrexate during each induction course and the drugs of the consolidation phase. In cases of initial CNS localization, cranial radiotherapy was added. Eighty-four patients (87%) went into complete remission (CR), 18 (21%) of whom relapsed, usually during the phase of treatment or within 6 months of completing chemotherapy. Sixty-three patients are alive with an overall median follow-up of 24 months. The median survival time and the median disease-free survival have not been reached, and the survival curve seems to have plateaued at above 60%. There was no statistical difference between intermediate-grade ML (CR 90%, relapse 18%) and high-grade ML (CR 84%, relapse 24%). The toxicity of this treatment is mainly encountered during the induction phase: almost all patients had short-term neutropenia, less than 0.500 g/L in 57, with a documented infection in 25. Overall treatment-related mortality was 6%, with four patients dying during the induction phase.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) to increase efficacy of intensive sequential chemotherapy with etoposide, mitoxantrone and cytarabine (EMA) in previously treated acute myeloid leukemia: a multicenter randomized placebo-controlled trial (EMA91 Trial)

The EMA86 study showed efficacy of intensive sequential chemotherapy with mitoxantrone, 12 mg/m2 day on days 1-3, etoposide, 200 mg/m2/day as a continuous infusion on days 8-10 and cytarabine (araC), 500 mg/m2/day as continuous infusion on days 1-3 and 8-10 (EMA regimen) in previously treated patients with AML. The goal of the EMA91 study was to determine whether administration of GM-CSF between the two sequences of EMA chemotherapy and during the second sequence could increase therapeutic efficacy by potentially increasing leukemic cell recruitment into the S phase of cell cycle before the second sequence. One hundred and ninety-two patients aged less than 65 years with previously treated AML received GM-CSF, 5 microg/kg/day or placebo from day 4 to day 8 of EMA chemotherapy. One hundred and twenty were refractory and 72 were in first relapse after a complete remission (CR) of more than 6 months duration. CR rates after one course of chemotherapy were 65% in the GM-CSF group (refractory: 51%; first relapse: 89%), not significantly different from the 59% CR rate (refractory: 46%; first relapse: 81%) in the placebo group. Median time to recovery of neutrophils was 38 and 37 days and median time to last platelet transfusion 32 and 32 days respectively in the GM-CSF and placebo groups. WHO grade > or = 3 non-hematologic toxicities were mainly sepsis (45% and 51%, respectively) and mucositis (34% and 31%) and did not differ between the two groups. Toxic death rate was 5% and 8%, respectively, in the GM-CSF and placebo groups. Patients achieving CR were scheduled to receive six courses of maintenance with reduced-dose EMA. Time to progression tended to be longer in the GM-CSF group (median 154 vs 115 days, progression-free rate at 18 months 33% vs 19%, P = 0.08), particularly in refractory patients (P = 0.06). However, at the current follow-up, this did not translate into a significantly longer disease-free survival and survival. Cell cycle studies showed increased recruitment of cells in the S phase between day 4 and day 8 in the GM-CSF group compared to placebo (P = 0.006). However, this did not significantly relate to prognosis in this cohort of patients. GM-CSF might marginally increase efficacy of sequential chemotherapy without increasing its toxicity in the absence of any detected relationship between this effect and observed leukemic cell recruitment into the cell cycle.

The syndrome of abnormal chromatin clumping in leucocytes: a myelodysplastic disorder with proliferative features?

Five patients presenting extremely exaggerated chromatin clumping in leucocytes, associated with a loss of segmentation, are described. Peripheral cytopenia, a high percentage of circulating immature granulocytes (chiefly myelocytes) with variable leucocytosis, marrow hypercellularity with granulocytic hyperplasia and moderate dysplastic changes in erythroblastic and megakaryocytic lines, constitute, together with the granulocytic nuclear anomaly, the characteristic features of the studied cases. Cytogenetic analysis showed a clonal 12p anomaly in one of the three cases available for study. Survival was poor with a median of 15 months, bleeding and infections being responsible for the majority of deaths. All these findings point to abnormal chromatin clumping in leucocytes as the marker of a true entity with both myelodysplastic and myeloproliferative features. We propose that it take its place among myelodysplastic syndromes (MDS) beside chronic myelomonocytic leukaemia (CMML), with which it shares many similarities in clinical and biological behaviour.

Break in the BCL1 locus is closely associated with intermediate lymphocytic lymphoma subtype

The t(11;14)(q13;q32) is a recurring translocation associated with some chronic B-cell lymphocytic malignancies; the putative protooncogene BCL1, located at the chromosome band 11q13, can be involved during the translocation process. In order to determine if BCL1 rearrangement is associated with a particular subtype of lymphoma, we analysed 131 B-cell non-Hodgkin's lymphoma samples by Southern blot analysis, using a BCL1 probe. The BCL1 locus was rearranged in 9 out of 25 (36%) cases of intermediate lymphocytic cell lymphomas (ILL), in 1 out of 8 cases of diffuse small cleaved cell lymphoma, in 1 out of 12 cases of diffuse mixed cell lymphoma, and in 1 out of 21 cases of diffuse large cell lymphoma. In contrast, BCL1 was never found rearranged in any of the 46 follicular lymphomas analysed. The BCL2 gene was in germ-line configuration in all ILL. Sequential hybridization of Southern blots with JH, C mu, and BCLI probes identified comigrating fragments in only one case of ILL, which suggests that, in all the other cases, either the rearrangement of BCL1 did not result from a t(11;14) translocation or the break on chromosome 14 occurred outside the JH or C mu regions. These results indicate that rearrangement of the BCL1 locus may be closely associated with ILL and could be considered as a genotypic marker of this lymphoma subtype.

Prognostic value of miR-16 expression in childhood acute lymphoblastic leukemia relationships to normal and malignant lymphocyte proliferation

miR-16, a miRNA involved in cell proliferation and apoptosis regulation, may interfere with either oncogenic or tumor-suppressor pathways and is implicated in leukemogenesis. We then explored its expression in 93 childhood acute lymphoblastic leukemia (ALL) cases. A high miR-16 expression was associated with hyperleukocytosis and poor cytogenetic groups. In the whole group and in B-cell ALLs, disease-free survival (DFS) was significantly shorter for miR-16 above quartile 75. In T-cell ALLs, for both DFS and overall survival, a significant trend was found with a survival shortening from the lowest to the highest miR-16 levels. miR-16 expression neither significantly correlated with normal and malignant lymphocyte proliferation nor varied according to lymphocyte differentiation. The prognostic value of miR-16 in childhood ALL highlighted the complexity of miR-16 functions.

The Australian Vietnam Veterans Health Study: II. self-reported health of veterans compared with the Australian population

BACKGROUND

Self-reported physical health status of Australian Vietnam veterans was determined 20-25 years after the war and its relation to combat was investigated.

METHOD

An epidemiological cohort study of a simple random sample of Army veterans posted to Vietnam between 1964 and 1972 was conducted with personal interviews using the Australian Bureau of Statistics Health Interview Survey questionnaire to compare veterans with the Australian population and a 21-item combat exposure index used to measure the relationship of combat to physical health.

RESULTS

Veterans reported greater health service usage and more recent health actions than population expectations. They also reported excess health problems in almost all recent illness disease categories except endocrine conditions and cardiovascular conditions; only 6 of 37 chronic disease groups were not elevated compared to the population. Adjustment for non-response changed estimates only slightly. Combat exposure was significantly related to reports of recent and chronic mental disorders, recent hernia and chronic ulcer, recent eczema and chronic rash, deafness, chronic infective and parasitic disease, chronic back disorders and symptoms, signs and ill-defined conditions.

CONCLUSION

Combat exposure may have significantly increased reports of only some health problems. A general position to complain as a result of psychological conditions due to combat is not consistent with the lack of relationship between combat and reports of physical conditions.

Glucocorticoids induce G1 as well as S-phase lengthening in normal human stimulated lymphocytes: differential effects on cell cycle regulatory proteins

In order to analyze dexamethasone effects on peripheral blood lymphocyte proliferation, we defined various experimental conditions: dexamethasone introduced (i) at the time of phytohemagglutinin stimulation, (ii) 48 h after the beginning of phytohemagglutinin stimulation, and (iii) on unstimulated lymphocytes. In stimulated lymphocytes, we observed an early G1 accumulation (P < 0.005), a delayed increase in the duration of S-phase (P < 0.03), and a consequent increase in cell-cycle duration. The expression of several cyclins, cyclin-dependent kinases (CDKs), and CDK inhibitors (CKIs) was modified. Cyclin D3, CDK4, and CDK6 involved in G1-phase control were significantly decreased under dexamethasone treatment whatever the level of stimulation of lymphocytes (stimulated or unstimulated PBL). Cyclin E and CDK2, acting in G1/ S-phase transition and S-phase regulation, decreased in stimulated lymphocytes before any modification of S-phase (P < 0.002). The expression of CKIs, mainly of p27Kip1, appeared to vary with the degree of cell stimulation: a decrease was observed on treated unstimulated lymphocytes, while p27Kip1 increased in dexamethasone-treated cells during stimulation. Our results indicate sequential modifications of the cell-cycle regulation by dexamethasone starting with an action on G1 followed by S-phase control modifications. The protein analysis pinpoints the major complexes concerned: CDK4 and CDK6/cyclin D are mainly involved in G1-phase modifications, while CDK2 and its partner, cyclin E, might be specifically involved in the lengthening of S-phase. The variations observed for p27Kip1 might amplify the functional effects of dexamethasone on kinasic complexes.

Significant Reduction in the Binding of a Monoclonal Antibody (LYP 18) Directed Against the IIb/IIIa Glycoprotein Complex to Platelets of Patients Having Undergone Extracorporeal Circulation

Extracorporeal circulation (ECC) used in open heart surgery gives rise to several hemostatic defects. This work investigates the effect of ECC on patient platelets membrane glycoproteins II b/ IIIa. A monoclonal antibody (LYP 18) directed against the IIb/ IIIa complex was used on patient platelets in binding and flow cytometry studies, before and at the end of ECC. An antithrombospondin (LYP 8) monoclonal antibody and a monoclonal antibody (LYP 7) directed against an a-granule glycoprotein of 136 kdaltons, present on the platelet surface after secretion, were used in binding studies together with electron microscopy to assess the release of α-granules.

Results obtained in 7 patients show a significant reduction (p <0.02) in the number of LYP 18 monoclonal antibody binding to platelets having undergone ECC (n = 49,725 ± 16,275) compared to platelets drawn before ECC (n = 72,671 ± 13,302). Flow cytometry studies indicate a decrease (p <0.02) in the percentage of platelets bearing the LYP 18 determinant following ECC (75 ± 12% vs 66 ± 14%). Binding of monoclonal antibodies LYP 8 and LYP 7 and electron microscopy studies of patient platelets having undergone ECC do not show degranulation. These results suggest possible cleavage of the IIb/IIIa complex following ECC but no release of α-granules.

ckshs expression is linked to cell proliferation in normal and malignant human lymphoid cells

Cyclin kinase sub-units (CKS) are known to interact with cyclin-dependent kinases (CDKs), but their functions are not completely understood and their expression in human tissues is not documented. For analyzing relationships of CKS with cell proliferation and/or with differentiation, we investigated the expression of ckshs1 and ckshs2 in normal and malignant human lymphoid cells. ckshs1 and ckshs2 expression appeared to be related to cell proliferation: (i) mRNAs increased with stimulation of normal peripheral-blood lymphocytes, and from the G1 to the SG2M phase in elutriated cells; (ii) P9 proteins were also induced by lymphocyte stimulation and were localized in nucleus where phosphorylated forms of CDK1 were also found; (iii) in vitro, the phosphorylated forms of CDK1 and CDK2 were preferentially linked to CKS. Among 45 patients presenting acute or chronic lymphoid malignancy, ckshs1 and ckshs2 mRNAs varied in a similar way and were significantly correlated to cell proliferation (p < 0.0001). When analysis was restricted solely to acute lymphoblastic leukemia (ALL) this correlation was still found and ckshs1 and ckshs2 were significantly more expressed in T-cell ALL than in B-cell-lineage ALL. These results confirm relationships between ckshs expression and cell proliferation, and pose the question of a link with cell differentiation.

Enhanced expression of p16ink4a is associated with a poor prognosis in childhood acute lymphoblastic leukemia

The tumor suppressor gene p16ink4a is homozygously deleted in numerous T as well as in some B lineage acute lymphoblastic leukemia (ALL). We therefore analyzed the clinical and biological implications of this feature by studying p16ink4a expression in 58 cases of childhood ALL. mRNA and protein were significantly correlated and both appeared more highly expressed in B than in T lineage ALLs: 13 out of the 15 T cell ALLs did not show any p16ink4a expression. The main result of this study is the strong prognostic value of p16ink4a expression. When stratifying the patients in three groups according to p16ink4a expression, we observed in univariate analysis: (1) the shortest disease-free survival for patients presenting a high p16ink4a level; (2) contrasting with the good prognosis in the group of patients expressing p16ink4a at low level; (3) while cases without any expression of the inhibitor were associated with a medium course of the disease (P=0.0165). This prognostic value was confirmed by the multivariate analysis showing therapeutic regimen and p16ink4a protein expression as the only variables retained in the model. A specific metabolic profile related to cellular survival and proliferation was observed in each of the three p16ink4a expression groups. Among the cell cycle-related proteins we analyzed, only p21waf1 bcl-2 and CDK4 were significantly and positively correlated to p16ink4a. Furthermore, CDK6 was also strongly expressed in the group of cases with high p16ink4a level. An enhancement of p16ink4a, p21waf1 and bcl-2 was previously described in prolonged cellular survival, while aging cells showed a decrease in CDK4 expression. The concomitant high expression of the oncogenic protein CDK4 (and of CDK6), we observed, may amplify the leukemic advantage of prolonged lifespan blast cells by favoring cell progression through G1 phase. These data suggest that at least two mechanisms may be associated in the oncogenesis of very aggressive ALLs, ie deregulation of cell multiplication and prolonged blast lifespan.

The Australian Vietnam Veterans Health Study: I. study design and response bias

BACKGROUND

The Australian Vietnam Veterans Health Study was set up to examine the post-war health of former soldiers 20 or more years after service and to examine the relation of combat exposure to physical and mental health.

METHOD

A prospective cohort study of a simple random sample of 1000 male Australian Army Vietnam veterans used information gathered from Army records, from personnel interview and questionnaires. Military records were used to examine response bias by determining the differences between 641 interviewed veterans, 50 known deceased veterans and 309 non-respondents (including 48 refusers and 213 non-traceable).

RESULTS

Differences were evident between respondents and non-respondents, with logistic regression modelling pointing to pre-enlistment employment, antisocial behaviour, intelligence and post-Vietnam AWOL (absent without leave) as the most important discriminants with non-respondents performing worse. Compared to respondents, deceased left school earlier, had higher rank in Vietnam and at discharge, had a higher overall number of charges but not a higher rate overall, and were less likely to have gone AWOL. Deceased also received more casualty reports than respondents and non-respondents, were better behaved during service, and were better emotionally adjusted than non-respondents. Respondents compared with the Australian population had equivalent or better current socioeconomic status.

CONCLUSION

There seems little bias due to non-response, but deceased tend to come from and older cohort than in the other two groups.

Post-transplant lymphoproliferative disorders with genetic abnormalities commonly found in malignant tumours

Post-transplant lymphoproliferative disorders (PTLD) are potentially fatal complications of organ transplants. Impairment of the immune system by immunosuppressive drugs is the assumed cause of PTLD. The Epstein-Barr virus (EBV) is detected in most of the PTLD studied and is considered as the main aetiological agent. The clinical course of PTLD patients remains unpredictable, some lymphoproliferations regress after discontinuation of the immunosuppressive treatment, others behave as true malignant tumours. The mechanism by which a viro-induced lymphoproliferation evolves to an autonomous tumour remains unclear, and little is known about the genetic changes that occur during this process. We report two cases of fatal EBV-associated PTLD in heart transplant recipients. Both tumours were monoclonal and carried numerous chromosomal abnormalities, including a classic t(8;14)(q24;q32) with rearrangement of the MYC proto-oncogene. One tumour demonstrated an amplification of the proto-oncogene N-MYC. The EBNA2 gene was not expressed in tumoral cells, suggesting that the chromosomal abnormalities contributed the function of EBNA2 in these cells. The morphology of the tumours indicated that the cases presented here were not Burkitt's lymphomas. These findings provide some clues with regard to the genetic changes which lead to a B-cell malignancy in some transplant patients.

Cell-cycle, protein content, and nuclear size in acute myeloid leukemia

Simultaneous analysis of DNA and cellular proteins provides information on cell proliferation and metabolism. Cellular protein content coupled with nuclear geometric parameters can be used to evaluate cellular maturation and differentiation. In this study, leucoblasts from 50 cases of adult acute myeloid leukemia were analyzed by flow cytometry, and semiautomatic morphometry was performed on bone marrow smears. Ethanol-fixed bone marrow blast cells were stained for DNA with propidium iodide (PI) and for proteins with fluorescein isothiocyanate (FITC). On the resulting FITC versus PI histograms we defined the cells with low protein content which are associated with a nonproliferating subpopulation (LPC fraction). Low protein content fraction and S-phase are correlated (p less than 0.01). The LPC fraction values are more dispersed than S-phase values and thus should indicate more clearly eventual differences between cellular populations. This hypothesis has been tested with the prognostic significance of cell-cycle variables: The LPC fraction was significantly higher in the complete remission group than in the other (p less than 0.01), while S-phase did not show any difference. The peak value of the protein content histograms is significantly lower in the granulocytic leukemias (M1, M2, M3) than in the leukemias with a monoblastic component (M4, M5). Furthermore, we showed that the differentiation and the maturation of the myeloid blast cells modify the nuclear size. The combination of these two parameters provides useful information for cytological classification.

CDK1 and cyclin A expression is linked to cell proliferation and associated with prognosis in non-Hodgkin's lymphomas

Cellular proliferation is regulated by several kinasic complexes associating cyclins and their catalytic subunits cyclin-dependent kinases (CDKs). In order to gain insight into the mechanisms underlying proliferation in non-Hodgkin's lymphoma (NHL), we examined the expression of certain cell cycle regulatory proteins normally expressed in lymphoid cells, cyclins A, B, D3 and E and cdk1, 2, 4, and 6. In 70 patients presenting a previously untreated lymphoma, cyclins and CDKs were studied by Western blotting and quantified by densitometry. Flow cytometry study of DNA content was carried out for all patients in order to study cell proliferation and level of ploidy. The results were analysed according to the histological types, the immunological phenotypes of the lymphomas and the outcome of the patients. Cdkl and cyclin A were correlated with the percentage of cells in S and S+G2/M phases, and significantly different according to the grade of malignancy, with the lowest expression in low-, and the highest in high-grade NHL according to the Working Formulation. In B-NHLs, cdk1, cyclin A, as well as cdk2, cyclin D3 and E expression was higher in the aneuploid than in the euploid group. Our results point to some particularities of cell cycle regulation in two lymphoma sub-types: 1) a low expression of cyclin D3 and cdk6 in mantle cell lymphomas and 2) a discrepancy between the high proliferative activity and the level of protein expression in Burkitt's lymphomas. CDK1 and cyclin A showed a significant prognostic value for achievement of complete remission (Cdk 1) and for both disease free (cyclin A) and overall survival (cyclin A and cdk1): low protein level was associated with the best prognosis in B-NHLs. Our results show that differential cell cycle regulating protein expression may be associated with different biological and clinical behaviour of NHLs and confirm the usefulness of the study of cell cycle regulation as a tool for understanding lymphoid malignancies.

Long-term outcome and sequelae in aggressive lymphoma patients treated with the LNH-80 regimen

One hundred patients with aggressive malignant lymphoma treated with the LNH-80 regimen were evaluated for long-term survival, late relapse and long-term sequelae. The LNH-80 regimen consisted of three intensive courses of adriamycin, cyclophosphamide, vindesine and bleomycin, followed by consolidation and final intensification, as previously described. Of the eighty-four patients who achieved CR after induction, fifty-two are alive in continuous complete remission with a median follow-up of 9.2 years. Twenty-nine CR patients (35%) relapsed. Sixty-six percent of the relapses occurred during the first 18 months following the end of treatment but late relapses were observed up to 7 years off-therapy. The fifty-two long-term responders were evaluated for their ability to resume work, sexual function, fertility and presence of long-term sequelae. Of the 41 patients who worked before diagnosis of their disease, 66% had resumed their normal jobs and 24% had retired. Sexual activity was considered to be satisfactory by 66% of the patients. Eleven of the 15 patients (73%) who wanted children had between one and three children. Seven patients (14%) were considered to have mild long-term sequelae but all long-term survivors reported having an acceptable quality of life. Five of the patients who reached CR (6%) had second neoplasias. The LNH-80 regimen allowed 52% of the patients to benefit from long-term disease-free survival with minor long-term toxicity.

Cyclin-dependent kinase inhibitors (CKIs) and hematological malignancies

Cell proliferation control is ensured by a group of proteins named cyclin-dependent kinases (CDKs), the activation of which is dependent on phosphorylation and cyclin association. In parallel, these CDKs are negatively controlled by two distinct groups of inhibitory proteins, the cyclin-dependent kinase inhibitors (CKIs). The first group, including p16Ink4a, p15Ink4b, p18Ink4c and p19Ink4d, is specific for the G1 CDKs, CDK4 and CDK6, inhibiting the kinase activity of cyclin D/CDK4-CDK6 complexes on pRb. p16Ink4a, down-regulated by pRb, inhibits G1 CDKs by competition with cyclin D; p15Ink4b, the synthesis of which is induced by TGF beta, seems to be a mediator of TGF beta-mediated cell cycle arrest. Furthermore, p18Ink4c inhibits CDK6 phosphorylation and activation by CAK. The second CKIs family is constituted by p21Waf1, p27Kip1 and p57Kip2. Their inhibitory action concerns a large range of cyclin/CDK complexes involved in G1 and S phase. p21Waf1, induced in part by p53, is up-regulated by senescence, DNA damage and cellular differentiation. p21Waf1 forms quaternary complexes with CDKs, cyclins and PCNA. Its inhibitory action, preventing CDK from phosphorylation, depends on the stoichiometry of the components. As p15Ink4b, p27Kip1 causes late G1 cell cycle arrest after TGF beta treatment and contact inhibition. The implications of CKIs in hematological malignancies are function of deletions or mutations of their genes. p16Ink4a and p15Ink4b genes, localized on 9p21, present frequent homozygous deletions in ALL T, ATL and lymphoblastic acutisation of CML. The other CKIs present very rare homozygous deletions or mutations, particularly p21Waf1 and p27Kip2. However, reduction of inhibitory activity due to hemizygous deletions might favour leukemogenesis.

Differential expression of cell proliferation regulatory proteins in B- and T-lineage acute lymphoblastic leukaemias

In order to better understand the molecular background of differences between the clinical picture of T- and B-lineage ALLs, we studied the expression of several proteins involved in the regulation of cell proliferation in bone marrow blast cells from 30 cases of previously untreated acute lymphoblastic leukaemia (ALL); 14 cases were T- and 16 B-cell lineage ALLs. We studied several cyclin-dependent kinases (cdk1, cdk2, cdk4, cdk6) and cyclins (cyclin A, cyclin B1, cyclin D3 and cyclin E). We also studied proliferating cell nuclear antigen (PCNA) and Bcl-2 expression, the latter protein known to be involved in the prolonged survival of B-lineage ALL blasts. Proteins obtained from cell lysates were resolved on polyacrylamide gel followed by immunodetection and densitometry of specific bands. Expression of cdk1 and PCNA, markers of proliferative activity, was significantly higher in T- than in B-lineage ALL. Cdk6, which was highly correlated to PCNA, was also higher in T-cell ALL. In contrast, B-lineage ALL displayed a higher expression of anti-apoptotic protein Bcl-2. We hypothesize that those particularities may reflect differential roles of cell multiplication and apoptosis in the neoplastic proliferation of B- and T-lineage ALL.

Cdk1 is a marker of proliferation in human lymphoid cells

To better understand the relationship between the proliferation of human lymphoid cells and the expression of cdk1, a catalytic subunit of the histone H1 kinase (H1K), we examined its mRNA and protein content in 3 B-cell lines: Ramos, Reh-6 and IARC 963. Cells were elutriated according to their position in the cell cycle. Cell fractions were analyzed for cdk1 mRNA and protein cellular content by Northern blot and immunoblot, respectively, as well as for H1K activity. Both mRNA and protein amounts and H1K activity varied according to cell cycle phase, the lowest values being observed in G1-enriched fractions. For comparison, elutriated fractions were also tested for the expression of cdk2 and cdk4 proteins. Both showed some variations among fractions, but they were less clear than those of cdk1. We also tested 29 samples of lymphoid neoplastic and non-neoplastic tissues for proliferative activity (percentage of S and G2/M cells estimated by flow cytometry) and expression of cdk1, cdk2 and cdk4 proteins. We found a significant correlation between the percentage of cells in S or S + G2/M phases and cdk1 protein content but not cdk2 or cdk4 content. We conclude that cdk1 expression in human lymphoid cells varies during the cell cycle at both mRNA and protein levels.