Oral glucocorticosteroid-sparing effect of budesonide administered by Turbuhaler: a double-blind, placebo-controlled study in adults with moderate-to-severe chronic asthma. Pulmicort Turbuhaler Study Group

The purpose of this study was to evaluate the correlation between alteration in telomere length and prognosis in patients with pathological stage I-II non-small cell lung cancer. We measured telomeric repeat length and telomerase activity by use of southern blot analysis of terminal restriction fragments and a non-radioactive ELISA-based assay, respectively. RESULTS: Alterations in TRF lengths were present in 17(29.8%) of 57 patients. Patients with altered TRF length had significantly shorter survival than did patients without (P = 0.0051). In multivariate analysis, only alteration in TRF length independently correlated with shortened survival (P = 0.0033).     

Telomerase and telomere length in the development and progression of premalignant lesions to colorectal cancer

Telomerase and telomere length are increasingly studied as prognostic markers in malignancy. Telomerase is also known to be expressed in certain nonmalignant cells, although generally at low levels. We investigated telomerase activity and telomere length in premalignant, malignant, inflammatory, and normal colon specimens to determine whether significant differences exist and whether telomerase may serve as a marker for early- or late-stage colorectal cancer. Telomerase activity was evaluated in 130 frozen specimens from human colon cancer (n = 50), adjacent normal colon tissue (n = 50), colon polyps (n = 20), and colitis (n = 10) using a modified telomeric repeat amplification protocol assay, and telomere length was assessed by terminal restriction fragment analysis. High to moderate levels of telomerase activity were detected in 90% of colorectal tumors. Weakly positive activity was detected in 10%. None of the normal tissues exhibited telomerase activity. In polyps and colitis, telomerase activity was found in 60% (12 of 20) and 40% (4 of 10), respectively. Telomerase activity in both nonmalignant lesions was 25- to 54-fold lower than that detected in colon cancer (P < 0.001). We found a positive correlation between tumor cell infiltration determined in cryostat sections and telomerase activity (r = 0.886; P > 0.0001). Late-stage tumors (Dukes C + D) demonstrated increased telomerase activity compared to early-stage tumors (Dukes A + B). Telomere restriction fragments in colon tumors had peak values of 4.8 +/- 1 kbp that were significantly and consistently shorter than those of the adjacent normal tissues (7.54 +/- 1.3 kbp), polyps (7.5 +/- 0.7 kbp), and colitis specimens (7.7 +/- 0.5kbp; P < 0.0001). Telomeres were 0.6 kbp longer in tumors with high telomerase activity and in late-stage cancers (Dukes C + D) compared to those in tumors with low telomerase activity and in early-stage cancers (Dukes A + B). Our data demonstrate that telomerase in colon cancer was commonly acquired, and activity was higher than that in polyps and colitis. However, weak telomerase activity was detected in premalignant and inflammatory lesions. Telomeres in colon cancer were considerably shorter, an indication of extensive cell proliferation and population divisions, whereas adjacent normal colon specimens, polyps, and colitis had comparable telomere lengths. Our results indicate that increased telomerase activity occurs in colon cancer cells that have undergone extensive telomere shortening relative to surrounding normal tissues and in which telomerase-induced stabilization of telomeres may be critical for the continued proliferation of the malignant clone. The link between telomerase activity and stage suggests that telomerase is up-regulated as a function of increased tumor cell invasion, tumor progression, and metastatic potential in colon cancer.     

Relationship between telomere length and clinical and biological characteristics of the cancers with telomerase reactivation

Activation of telomerase and stabilization of telomeres are considered to be necessary for immortalization of human tumor cells. Telomerase activity and telomere lengths were examined in adult and childhood cancer tissues. High telomerase activity was detected in over 40% samples. In these cases, the lengths of telomeres varied in wide range and the short telomere length significantly correlated with high proliferative index. The patients with short telomeres demonstrated poorer prognosis than other patients. These findings suggest that the short telomeres might be related with the malignant potential in cancers with high telomerase activity.     

Decrease of telomere length in thyroid adenomas without telomerase activity

In somatic cells, telomeres shorten with population doubling, thus limiting their capacity to divide. Telomerase, which synthesizes telomeric repeats, can compensate for such shortening. Telomerase activity is known to be absent from most somatic differentiated cells but is present in germline cells, immortal cell lines, or a large majority of malignant tumors. Autonomous thyroid adenomas are benign tumors composed of highly differentiated cells characterized by TSH-independent function and growth. Telomere length and telomerase activity were measured in autonomous and hypofunctioning adenomas and their surrounding tissues. A significant decrease of 3.8+/-1.0 kilobases (kb) was observed in the length of the terminal restriction fragments (TRF) in 12 autonomous adenomas (8.6+/-1.1 kb), compared with the TRF length of their surrounding tissues (12.4+/-1.6 kb). The same kind of decrease, 3.5+/-1.2 kb, was also observed in 16 hypofunctioning adenomas (12.3+/-1.7 kb in surrounding tissue and 8.8+/-1.6 kb in the adenomas). No telomerase activity was detected either in the 12 autonomous adenomas studied or in most of the quiescent tissues (10 of 12). Most of the hypofunctioning adenomas tested (15 of 16) did not display telomerase activity. These results suggest that the cells have undergone a higher number of cell divisions in the adenomas than in the surrounding tissue. Moreover, there is a larger spread of the TRF length distribution in autonomous adenomas than in the collateral tissue. This could reflect the heterogeneity in proliferation status of the cells in the nodule, some of which have reached the end of their life span, whereas others are still proliferating (but with no malignant potential for the autonomous adenomas). In conclusion, benign adenomas exhibit a shorter and more variable telomere length than the normal collateral quiescent tissue, with no telomerase activity to compensate this loss in telomere length.     

Telomere, telomerase and cytogenetic changes in myelodysplastic syndromes

Myelodysplastic syndrome (MDS) is a heterogenous but clonal disorder characterized by cytopenia and dysplastic features. Telomere length in MDS vary but some of them show shortened telomeres. Telomerase activity in MDS also vary but about 60% of them show slightly elevated telomerase activity. According to the disease progression of MDS, MDS patients categorize into 3 groups, i.e., (1) normal telomere length before and after disease progression, (2) short telomere length before and after progression, and (3) shortened telomere with disease progression. Telomerase change with disease progression is not obscure, indicating impairment of telomere dynamics in MDS. These observations may indicate that some MDS show telomerase upregulation possible due to telomere shortening, while the another pathway without telomerase upregulation associated with complex chromosome changes may link to the pathogenesis of MDS.     

Telomere length regulation in mice is linked to a novel chromosome locus

Little is known about the mechanisms that regulate species-specific telomere length, particularly in mammalian species. The genetic regulation of telomere length was therefore investigated by using two inter-fertile species of mice, which differ in their telomere length. Mus musculus (telomere length >25 kb) and Mus spretus (telomere length 5-15 kb) were used to generate F1 crosses and reciprocal backcrosses, which were then analyzed for regulation of telomere length. This analysis indicated that a dominant and trans-acting mechanism exists capable of extensive elongation of telomeres in somatic cells after fusion of parental germline cells with discrepant telomere lengths. A genome wide screen of interspecific crosses, using M. spretus as the recurrent parent, identified a 5-centimorgan region on distal chromosome 2 that predominantly controls the observed species-specific telomere length regulation. This locus is distinct from candidate genes encoding known telomere-binding proteins or telomerase components. These results demonstrate that an unidentified gene(s) mapped to distal chromosome 2 regulates telomere length in the mouse.     

Telomerase activity in human acute myelogenous leukemia: inhibition of telomerase activity by differentiation-inducing agents

The terminal regions of human chromosomes, the telomeres, shorten with each cell division in most normal somatic cells. Telomerase, a ribonucleoprotein that synthesizes telomeric DNA onto chromosomal ends, is activated in germline cells and almost all tumor cells. Telomerase activity maintains the stability of telomere length, resulting in indefinite cellular proliferation (immortality). In the present study, telomerase activity was analyzed in leukemic mononuclear blood cells obtained from 56 patients with acute myelogenous leukemia (AML) with known cytogenetic alterations. Heterogenous levels of telomerase activity were observed and generally correlated with cytogenetic status. Patients with 11q abnormalities and -5/-7 (unfavorable cytogenetics) tended to have high telomerase activity compared with cells obtained from AML patients with other types of cytogenetics. Additional studies with a larger cohort of patients will determine whether these differences are statistically significant. Chemotherapy agents that result in differentiation of leukemic cells also resulted in inhibition of telomerase activity. Knowledge of telomerase activity in patients with AML, before and throughout therapy, may have clinical utility for following disease progression and may predict early cancer relapse.     

Sensitivity of the N-methyl-D-aspartate receptor channel to butyrophenones is dependent on the epsilon2 subunit

Li-Fraumeni Syndrome (LFS) is characterized by heterozygous germline mutations in the p53 gene. Accompanied by genomic instability and loss or mutation of the remaining wild type p53 allele, a low frequency of spontaneous immortalization in LFS fibroblasts occurs. It is believed that the loss of p53 wild type function contributes to immortalization of these LFS fibroblasts, but it is not clear if this is sufficient. Because stabilization of telomere length is also thought to be a necessary step in immortalization, telomerase activity, expression of the telomerase RNA component (hTR) and telomere length were anlaysed at various passages during the spontaneous immortalization of LFS skin fibroblasts. One LFS strain which immortalized, MDAH087 (087), had no detectable telomerase activity whereas another LFS strain which immortalized, MDAH041 (041), had detectable telomerase activity. In preimmortal cells from both strains, hTR was not detected by in situ hybridization. Immortal 087 cells remained negative for hTR, while immortal 041 cells demonstrated strong hTR in situ hybridization signals. 087 cells had long and heterogenous telomeres whereas telomeres of 041 cells had short, stable telomere lengths. Tumorigenicity studies in nude mice with ras-transformed 087 and 041 cells resulted in both cell lines giving rise to tumors and retaining telomerase status. Overall these results suggest that strain specificity may be important in telomerase re-activation and that both abrogation of p53 function and a mechanism to maintain telomeres are necessary for immortalization.     

Rap1 protein regulates telomere turnover in yeast

Telomere length is maintained through a dynamic balance between addition and loss of the terminal telomeric DNA. Normal telomere length regulation requires telomerase as well as a telomeric protein-DNA complex. Previous work has provided evidence that in the budding yeasts Kluyveromyces lactis and Saccharomyces cerevisiae, the telomeric double-stranded DNA binding protein Rap1p negatively regulates telomere length, in part by nucleating, by its C-terminal tail, a higher-order DNA binding protein complex that presumably limits access of telomerase to the chromosome end. Here we show that in K. lactis, truncating the Rap1p C-terminal tail (Rap1p-DeltaC mutant) accelerates telomeric repeat turnover in the distal region of the telomere. In addition, combining the rap1-DeltaC mutation with a telomerase template mutation (ter1-kpn), which directs the addition of mutated telomeric DNA repeats to telomeres, synergistically caused an immediate loss of telomere length regulation. Capping of the unregulated telomeres of these double mutants with functionally wild-type repeats restored telomere length control. We propose that the rate of terminal telomere turnover is controlled by Rap1p specifically through its interactions with the most distal telomeric repeats.     

A prospective study of prognostic value of type IV collagenase activity in colorectal cancer tissue

The purpose of this prospective study was to evaluate the prognostic value of the type IV collagenase (IVase) activity in colorectal cancer tissue on disease-free and overall survival in 31 colorectal cancer patients. The clinicopathologic factors studied for prognostic value were age, tumor location, tumor differentiation, preoperative serum levels of carcinoembryonic antigen, Dukes' stage, and IVase activity in colorectal cancer tissue. IVase activities in colorectal cancer tissue were significantly higher in the group of patients with recurrences than in the group without recurrences (P = 0.019). Patients with high IVase activity in colorectal cancer tissue had a significantly shorter disease-free survival (P = 0.0016) and overall survival (P = 0.022) time than those with low IVase activity. Univariate and multivariate analysis showed that significant prognostic factors for disease-free survival were Dukes' stage (P = 0.029, P = 0.046, respectively) and IVase activity status (P = 0.0016, P = 0.0026, respectively). With respect to overall survival, only IVase activity status provided significant predictive value in multivariate analysis (P = 0.041). This prospective study suggests that IVase activity is a valuable prognostic factor in colorectal cancer patients.     

Possible mechanisms for the regulation of telomere length

Since DNA polymerases can only synthesise a new DNA strand in the 5'-3' direction and need a primer that provides a free 3' OH end, the cellular replication machinery is unable to duplicate the 3' ends of linear chromosomes unless special mechanisms are operative. While the telomeres seem to shorten continuously in human somatic cells because of the "end replication" problem, it appears that telomere length is maintained in cancer cells, the germ line and unicellular organisms like yeast and Tetrahymena by a mechanism involving the enzyme telomerase, which elongates the 3' ends of telomeres. However, telomerase must be part of a more complicated mechanism to ensure that there is no net gain or loss of telomeric ends. Here we describe a simple theoretical model that can explain several experimental findings. The simulations show that (i) the proposed mechanism is able to maintain telomeres at a constant length, (ii) this length constancy is independent of the initial telomere length, (iii) mutations of the telomeric sequence lead to an elongation of telomeres, (iv) inhibition of telomerase causes telomeric shortening, and (v) it reproduces and explains the experimental result that the addition of oligonucleotides to the culture medium leads to an increase of telomere length.     

Community hospitals and general practice: extended attachments for medical students

Telomerase activation has been shown to be an almost universal property of malignant tumors evoking its role in the immortalisation process. We used the recently described sensitive and rapid detection assay called telomeric repeat amplification protocol (TRAP) to detect telomerase activity in neoplastic and non neoplastic tissues. Human telomerase is a ribonucleoprotein which functions as a telomere terminal transferase by adding multiple repeats of the TTAGGG hexamer at the 3'-OH ends of either telomeres or oligonucleotide specifically designed for the TRAP assay. Whenever present, telomerase activity is revealed on acrylamide gel by a six nucleotide ladder of extension products. Detection of telomerase activity may be evaluated for differentiating neoplastic from non neoplastic tissues. In addition, quantitation of telomerase activity may serve as prognostic marker for malignant tumors.     

Diminished production of interleukin-6 in chronic lymphocytic leukaemia (B-CLL) cells from patients at advanced stages of disease. Tampere CLL Group

The production of the cytokines interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) in B-CLL cells from 24 patients at different stages of chronic lymphocytic B-cell leukaemia (B-CLL) was investigated in vitro. In the majority of these cases, low spontaneous IL-6 production was measured. Mitogenic stimulation with phorbol 12-myristate 13-acetate (PMA) or PMA plus interleukin-2 (IL-2) resulted in a tremendous increase in TNF-alpha and IL-6 production in cells representing early stage (Binet A) disease. In contrast, very little, if any, production took place in cells from patients with advanced stage (Binet C) B-CLL. The results from stage B patients were intermediate. The most remarkable difference was recorded in PMA-stimulated (1 ng/ml) IL-6 production. In stimulated 72 h cultures, IL-6 concentrations were 1280 +/- 1080 pg/ml for Binet A (n = 11), 757 +/- 597 pg/ml for Binet B (n = 8) and 46.0 +/- 84.0 pg/ml for Binet C (n = 5). The differences in IL-6 production between stage C v B and stage C v A were both statistically significant (P=0.025). Similar effects, but to a lesser extent, were observed in TNF-alpha production. These results suggest that the varying capacity to produce IL-6 and TNF-alpha may play a role in B-CLL progression and in clinical manifestations of the disease.     

Serum interleukin-6 in relation to acute-phase reactants and survival in patients with renal cell carcinoma

Patients with malignancies often present with signs of inflammatory reactions such as elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Since interleukin-6 (IL-6) is a possible regulator of these reactions and has been proposed as a predictor of prognosis, the aim of the study was to analyse its clinical significance in patients with renal cell carcinoma. Serum samples were collected from 196 patients before any treatment. IL-6 was analysed by an enzyme-linked immunoassay and compared with tumour grade, stage, acute-phase reactants and survival. Patients with renal cell carcinoma had significantly higher IL-6 levels (mean 28.1 +/- 63.4 ng/l; median 8.3 ng/l) compared with controls (mean 1.7 +/- 2.6 ng/l; median 0.5 ng/l; P < 0.001). Serum IL-6 levels in patients with distant metastases were significantly higher than for patients with tumours confined to the kidney (P = 0.02). This difference was more pronounced when serum IL-6 levels in patients with poorly differentiated tumours were compared with well-differentiated tumours (P < 0.001). A significant correlation between the acute-phase reactants CRP, ESR and IL-6 levels was found. Survival time was significantly shorter (P = 0.001) for patients with IL-6 levels above the median serum level compared with patients with lower levels. Similar significant prognostic results were obtained in the group of patients with metastatic disease, but not in group of patients with stage I-III. Serum levels of IL-6 correlated to tumour stage, grade and acute-phase reactants. Increased levels were related to the presence of metastases and adverse survival. Serum IL-6 proved univariate prognostic information but this prognostic significance was lost using a multivariate analysis.     

Injection of apomorphine into the medial prefrontal cortex of the rat increases haloperidol-induced catalepsy

We compared telomere length in donor leukemic cells and corresponding established cell lines from three patients with chronic myeloid leukemia (CML) and three with acute lymphoblastic leukemia (ALL) to study the relation between the immortalization capacity of hematologic neoplasms and telomere length. Six of the seven established leukemia cell lines (four CML and two ALL) carried additional chromosome changes and had shorter telomere repeats than those of the donor patients' leukemic cells; the remaining ALL line showed no significant difference in telomere length between fresh leukemic cells and the corresponding cell line. Thus, most established leukemic cells lose effective telomerase activity during the process of establishment, and reduction in telomere length of established leukemic cells appeared to be associated with the presence of additional chromosome changes.     

Senescence mutants of Saccharomyces cerevisiae with a defect in telomere replication identify three additional EST genes

The primary determinant for telomere replication is the enzyme telomerase, responsible for elongating the G-rich strand of the telomere. The only component of this enzyme that has been identified in Saccharomyces cerevisiae is the TLC1 gene, encoding the telomerase RNA subunit. However, a yeast strain defective for the EST1 gene exhibits the same phenotypes (progressively shorter telomeres and a senescence phenotype) as a strain deleted for TLC1, suggesting that EST1 encodes either a component of telomerase or some other factor essential for telomerase function. We designed a multitiered screen that led to the isolation of 22 mutants that display the same phenotypes as est1 and tlc1 mutant strains. These mutations mapped to four complementation groups: the previously identified EST1 gene and three additional genes, called EST2, EST3 and EST4. Cloning of the EST2 gene demonstrated that it encodes a large, extremely basic novel protein with no motifs that provide clues as to function. Epistasis analysis indicated that the four EST genes function in the same pathway for telomere replication as defined by the TLC1 gene, suggesting that the EST genes encode either components of telomerase or factors that positively regulate telomerase activity.     

Telomerase activity in ovarian tumors

BACKGROUND: Shortening of telomeres occurs with each cell division and eventually results in cell death. The activity of telomerase, an enzyme that catalyzes telomere elongation, has been detected in germ cell lines and cancer cells, and has been detected in immortal cell lines but not in normal somatic cells. The relationship between telomerase expression and ovarian carcinogenesis was investigated. METHODS: Ovarian tissue was obtained from 41 women with ovarian tumors (10 benign, 6 borderline-malignant, and 25 malignant tumors) and 6 with uterine disease (2 with uterine myoma and 4 with uterine carcinoma). These specimens were analyzed for telomerase activity and telomere length by the telomeric repeat amplification protocol and Southern blot hybridization, respectively. RESULTS: Telomerase activity was detected in 23 of 25 malignant ovarian tumors (92%), in 1 of 6 borderline-malignant tumors (16.7%), and in 2 of 10 benign tumors (20%) (both of which were germ cell tumors). Weak telomerase activity was present in the cortex of normal ovaries from premenopausal women, and appeared to be attributable to follicles. Telomerase activity in malignant and poorly differentiated tumors tended to be higher than that in other tumors. Terminal restriction fragment length ranged between 8 and 13 kilobase pairs (kbp) for normal ovaries, and was <8 kbp in 1 of 6 malignant Stage I tumors (16.7%), 1 of 2 Stage II tumors (50%), and 9 of 17 Stage III tumors (52.9%). CONCLUSIONS: Telomerase activity may be a useful marker for the diagnosis of ovarian tumors.