Double-stranded RNA-dependent protein kinase, PKR, down-regulates CDC2/cyclin B1 and induces apoptosis in non-transformed but not in v-mos transformed cells.

The interferon (IFN)-induced, double stranded RNA (dsRNA)-activated serine/threonine kinase, PKR, is a potent negative regulator of cell growth when overexpressed in yeast or mammalian cells. Paradoxically, while it can function as a tumor suppressor and inducer of apoptosis, it is overexpressed in a variety of human cancers. To resolve this enigma, we established cell-lines that overexpress PKR in non-transformed and in v-mos transformed CHO cells. Overexpression of PKR suppressed the proliferation of CHO cells by inducing a transient G0/G1 arrest, followed by a delayed G2/M arrest, which attenuated cell cycle progression. These effects were accompanied by early induction of p21/WAF-1 and delayed downregulation of CDC2 and cyclin B1. Induction of proapoptotic activity of the ectopic PKR paralleled the onset of G2/M arrest in CHO cells. However, while transiently inducing p21/WAF-1, PKR did not impose G2/M arrest or apoptosis in v-mos-transformed cells, nor was CDC2 or cyclin B1 down-regulated in those cells. These findings link the proapoptotic activity of PKR to the arrest of cell cycle at the G2/M phase. Consequently, the apoptotic activity of PKR could be counter-acted by an oncogene-like v-mos that overrides the G2/M arrest induced by PKR.

The effects of substituting zopiclone in withdrawal from chronic use of benzodiazepine hypnotics.

Twenty-four volunteers (19 women and five men) with insomnia and a history of chronic use of benzodiazepine hypnotics participated in a randomized, double blind, controlled clinical trial. The study was designed to assess the effects of substituting zopiclone (ZOP)- as an hypnotic- among chronic users of flunitrazepam (FLU), and to compare the subsequent withdrawal of ZOP with placebo controlled withdrawal of FLU. During the 5 weeks of a withdrawal protocol, sleep and physiological parameters were assessed by polysomnographic measures for 11 nights and by nightly actigraphic recordings for weeks 1, 3, and 5. Subjective effects of the withdrawal process were evaluated with daily sleep diaries, and with various weekly self-report symptom checklists. Paired t-tests performed on differences in objective sleep parameters between baseline and the last weeks of the withdrawal program showed a significant decrease in sleep quality within the FLU group, but not in the ZOP group. Subjective sleep diaries consistently reflected the objectively measured changes in sleep throughout the withdrawal program, indicating significant changes in sleep parameters only in the FLU group. The results obtained from the self report inventories aimed at assessing withdrawal symptoms, however, revealed no differences between the baseline week and the termination week of the program in any of the groups. After completing the pharmacological withdrawal, all subjects received a short-term cognitive behavioral intervention focused on improving their coping strategies with symptoms of insomnia; they were evaluated immediately after concluding the intervention, and at 3 and 12 month follow- ups.

Inhibition of 2-5A synthetase expression by antisense RNA interferes with interferon-mediated antiviral and antiproliferative effects and induces anchorage-independent cell growth.

It has been shown previously that the IFN-induced enzyme 2-5A synthetase is sufficient to induce antiviral and antiproliferative effects in transfected cells expressing the protein. In this study, the possibility that this enzyme is also essential in generating these biological activities was investigated. For this purpose, a plasmid, pMSas-NEO, was constructed. This plasmid carries an active neomycin-resistant gene. In addition, it contains a metallothionein promoter fused to an inverted 180-bp fragment derived from the 5' end of cDNA encoding the 43-kDa isoform of murine 2-5A synthetase. NIH/3T3 mouse fibroblasts were transfected with the plasmid, about 50 neomycin-resistant clones were isolated, and two, clone 11 and clone 22, were chosen for further studies. One clone transfected only with the neomycin-resistant gene, clone Neo, was used as a control. The results show that in the case of clone 11, the combined treatment of IFN and ZnCl2 reduced significantly the level of the IFN-induced 2-5A synthetase activity, the amount of the 40-, 43-, and 71-kDa 2-5A synthetase isoforms and the level of the 1.7-kb specific RNA transcript. An even stronger effect on these parameters was observed with clone 22 cells. No difference in PKR activity was evident under the same conditions with all three clones tested. Most important, the combined treatment of IFN and ZnCl2 reversed the IFN-mediated antiproliferative and antiviral activities, as determined by the kinetics of cell growth, thymidine incorporation, cloning efficiency, and infection with mengovirus. Strikingly, the growth of colonies in soft agar were observed in both clone 11 (small colonies) and clone 22 (large colonies) cells, particularly following treatment with ZnCl2. We conclude that 2-5A synthetase is an essential component in the IFN-induced biological activities and that interference with its function results in anchorage-independent growth of the transfected cells.

Involvement of interferon-system in the regulation of cell growth and differentiation.

In this report we review the current knowledge on the involvement of the interferon (IFN) system in the regulation of cell growth and differentiation. We also summarize our own data which provide evidence for the strong correlation between IFN-mediated growth-arrest of transformed cells and the elevated enzymatic activity of an IFN-induced protein. Similarly, it is demonstrated that elevated levels of IFN-induced proteins accompany the early phases of in-vitro cell differentiation. IFN-treatment of NIH/3T3 mouse fibroblasts transformed by Moloney-murine sarcoma virus (MSV) resulted in a significant reduction in the rates of cell growth, protein synthesis and cloning efficiency. In parallel, 2-5A-synthetase activity was induced ten-fold above the background level. Treatment of these cells for 3 days with 450 international units (IU)/ml of IFN followed by its removal, resulted in a gradual increase in all parameters associated with cell growth while the 2-5A-synthetase activity was reduced to its normal level. However, almost no recovery occurred when cells were treated with 1,800 IU/ml. In parallel, 2-5A-synthetase activity remained highly elevated even at 3 days after the removal of IFN. In these cells, the expression of both c-myc and v-mos was reduced rapidly following IFN treatment. Upon removal of IFN after 24 h of treatment, the expression of both genes was resumed but with a different kinetics, suggesting that different mechanisms are responsible for the reduction in gene expression. In rat skeletal muscle cultures which differentiate to form myotubes, the level of both 2-5A-synthetase and protein kinase activities was transiently elevated, reaching a peak at 3 days followed by a decrease to background levels. This peak activity precedes the appearance of the major muscle differentiating proteins.

Reversibility of the antiproliferative effect of interferon.

The reversibility of the antiproliferative effect of interferon (IFN) and its correlations to the induction of (2',5') oligoadenylate synthetase (2-5A synthetase) activity was studied on NIH/3T3 cells transformed by Moloney murine sarcoma virus. The cells were treated with various doses of mouse beta-IFN. At 72 h after treatment, the cultures were subdivided. While half received fresh doses of IFN, the second half received no IFN. Reversibility of the IFN effect was then followed. Three different parameters as indicators for cell proliferation were used: cell growth, protein synthesis and cloning efficiency. In parallel, the IFN-induced activity of 2-5A synthetase was determined. The data obtained led to the following conclusions. (1) The antiproliferative effect of IFN increases with increased IFN concentration (90-1,800 IU/ml) and with time of treatment, up to 72 h after treatment. (2) The induced activity of 2-5A synthetase increases with a much faster rate, reaching maximum activity at 24 h after treatment with 450 IU/ml. This means that the induction of the enzyme precedes the antiproliferative effects of IFN. (3) There is almost no recovery of the IFN antiproliferative effect following treatment for 72 h with high doses of IFN (1,200-1,800 IU/ml). However, at lower doses, recovery is evident. (4) Removal of IFN after treatment for 3 days with 450 IU/ml resulted in a gradual decrease of 2-5A synthetase activity, reaching the basal level at 72 h after removal. However, there is no reduction of enzyme activity following treatment for 72 h with 1,800 IU/ml of IFN.

Intestinal cancer in patients with Crohn's disease. A population study in central Israel.

A population study of Crohn's disease (CD) during the years 1970-1980 was performed in a defined area in central Israel with 1,400,000 inhabitants. Three hundred and sixty-five patients with definite CD were identified, and a complete follow-up was obtained with particular attention to intestinal cancer. The mean follow-up time was 9.95 years (range, 1-49 years). Forty-four per cent of the patients were operated on, but only a few had total colectomy or bypass operations. Only one patient developed colorectal cancer after 7 years of disease. The observed to expected ratio for this cancer was 1.14 at 10 years of disease and 0.73 at 20 years of disease. The incidence of colorectal cancer was not significantly different from the expected in the population. None of the patients developed small-bowel cancer. At least five patients had extraintestinal malignancies. A review of the literature showed conflicting results with regard to cancer risk in CD. The risk was not significantly increased in the two existing population studies, including the present one.

Colorectal cancer in patients with ulcerative colitis. A population study in central Israel.

The incidence of colorectal cancer was studied in an unselected group of 1035 patients (total group) with ulcerative colitis and in a subgroup of 822 who resided, at the time of diagnosis, within a defined area in central Israel (regional group). The operation rate was 5.2% and the follow-up period (mean +/- SD) was 11.5 +/- 8.3 yr, range 1-52 yr. The cumulative incidence of colorectal cancer in all patients was 0.2% at 10 yr, 2.8% at 15 yr, 5.5% at 20 yr, and 13.5% at 30 yr. The ratio of observed to expected cancer was 0.9 at 10 yr, 5.0 at 20 yr, and 6.4 at 30 yr. The cancer incidence was 1 case per 3895 patient-years in the first decade of disease, 1 case per 198 patient-years in the second decade, and 1 case per 100 patient-years in the third decade. All these figures were higher in patients with total colonic involvement. There were no significant differences between the total and regional patient groups. Onset of ulcerative colitis in the first and second decade of life was not associated with a higher cancer incidence when standardized for extent and duration of disease. The risk of colorectal cancer in patients with ulcerative colitis was more strongly expressed in population groups with a lower incidence of this cancer. The cumulative incidence of colorectal cancer in ulcerative colitis is much lower in population-based studies than that reported from major medical centers. Worldwide this incidence may also vary among different populations.

Childhood factors in ulcerative colitis and Crohn's disease. An international cooperative study.

This international case control study was conducted in 14 centers in 9 countries to investigate factors in childhood which may have a bearing on the etiology or pathogenesis of ulcerative colitis (UC) and Crohn's disease (CD). 197 patients with UC and 302 with CD (499 with inflammatory bowel disease (IBD] whose disease started before age 20 years and whose age at time of study was less than 25 years were investigated, with two age- and sex-matched controls for each patient. All subjects were studied with uniform questionnaires. Eczema was found significantly more frequently in patients with CD (p less than 0.005) and in their fathers (p less than 0.025), mothers (p less than 0.002), and siblings (p less than 0.01) as compared with their respective controls. IBD was significantly more frequent in parents, siblings, cousins, grandparents, and uncles of patients than in their respective controls. The fathers of patients with UC had significantly more major gastrointestinal and cardiovascular diseases at the time of the patient's birth than the fathers of controls. In North America mothers of patients with UC and CD took vitamin, mineral, and iron preparations during pregnancy significantly less frequently than mothers of controls. Patients with CD and UC consumed a lower residue diet than controls. Recurrent respiratory infections were more frequent in patients with UC and CD (p less than 0.001); it is uncertain whether this preceded disease. Hospitalization for respiratory diseases was more frequent in patients than controls, and the use of antibiotics more frequent in patients with CD. Smallpox vaccination was less frequent (p less than 0.05) in patients with CD, and chickenpox infection was less common in patients with UC (p less than 0.01). No significant differences were found between patients and controls in relation to various human and non-human contacts during childhood. Number of siblings, being an only child, and birth order did not differ markedly between patients and controls, and we could not confirm the 'sheltered child' hypothesis in IBD. The parents of controls were slightly better educated and their social class tended to be higher than those of parents of patients. There were significant associations between some of the main factors investigated in this study. No significant differences were found between patients and controls in the frequency of breast feeding, cereal consumption, sugar added to milk in infancy, gastroenteritis in childhood, major stressful life events, and many other factors.(ABSTRACT TRUNCATED AT 400 WORDS)

Serum interferon as a biological marker in malignant tumors.

A total of 745 serum interferon (IFN) determinations were carried out on the serum of 332 cancer patients with a variety of tumors. Disease activity was defined as either 'active' or 'nonactive' as based on clinical examination, the results of laboratory tests and radiological criteria. IFN levels were estimated for both disease activity and mode of treatment. A statistically significant higher level of IFN in the serum of active, as compared to that of nonactive disease, was established. Furthermore, a slight increase in the IFN level was observed in patients before initiating chemotherapy as compared to untreated patients, followed by a decrease in those patients undergoing chemotherapy. These differences between groups were not found to be statistically significant. However, in the cases of rectum, prostate and female genital cancers, a significant elevated level of serum IFN was observed at a late stage of the disease, followed by a decrease after chemotherapy treatment. In addition, a significant lower level of serum IFN was detected in breast cancer patients shortly after radiotherapy as compared to those before radiotherapy. We conclude that IFN, known to play a role in the control mechanisms of developing malignant processes, can be determined in the serum and used to monitor disease activity in individual patients. The inhibition of IFN release depends in part on therapy and can be used for monitoring treatment schedules along the course of disease.

Carcinoembryonic antigen and interferon as tumor markers in breast cancer.

A total of 239 determinations of CEA plasma levels were performed for 83 breast cancer patients during chemotherapy or follow-up. In addition, 137 plasma samples were assayed for interferon levels. Patient clinical status was carefully scored according to objective criteria and recorded at each evaluation. Liver function tests (LFT) were performed to establish a full clinical picture at each visit. The results obtained proved a 73 to 83% positivity rate when the results of the 4 tests were compared. The importance of routine CEA assays and careful clinical evaluation and LFT are stressed. An analysis of interferon levels defined 4 distinct groups that differed by the amount of interferon present and also by clinical status and CEA levels. The results are discussed in terms of tumor volume-dependent interferon production.