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Biomedical subjects

K Hiyama

Publications and source records attributed to K Hiyama.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Advance of research on telomerase].

Telomerase, a ribonucleoprotein enzyme which can compensate for the erosion of telomeric repeats each cell division, is considered to be associated with cellular immortality. The genes encoding the major components of human telomerase, TERC for telomerase RNA component, TEP1 for a human homolog of p80, and TERT for catalytic subunit, have been cloned. In addition, TERF1 and TERF2, encoding telomeric repeat binding proteins, have been cloned and shown to be involved in telomere length regulation and the protection of chromosome end fusions, respectively. Although the activity level of telomerase is similar at each stage of the cell cycle in telomerase-positive cells, it is generally upregulated with cellular proliferation and repressed with withdrawal from cell cycle. Although biological mechanisms regulating telomerase activity and telomere length remain elucidated, telomerase activity can be detected in approximately 85% of human malignant neoplasms, and the telomerase is a promising and novel tumor marker for clinical diagnosis of cancer, as well as a novel target of anticancer therapy.

Cell Cycle↗
PubMed1998

Telomerase activity as a novel marker of lung cancer and immune-associated lung diseases.

Telomerase maintains telomere length and is considered to be necessary for the indefinite proliferation of human cells. Telomerase activity is detected not only in germline and immortal cancer cells, but also in stem/progenitor cells of renewal tissues and activated lymphocytes. While it is generally agreed that telomerase is a useful tumor marker, the utility of telomerase activity in non-cancerous cells should also be considered. In the present study, we quantitatively examined telomerase activity in 56 cytology samples and 106 bronchoalveolar lavage samples obtained from patients with various respiratory diseases. Fourteen of 34 samples obtained from lung cancer patients showed detectable telomerase activity, while only 7 of 128 samples obtained from patients without lung cancer did (p<0.001). Moreover, 12 of 14 telomerase-positive samples with lung cancer showed strong signals, while none without lung cancer did. Among 106 non-cancerous bronchoalveolar lavage samples, 4 telomerase positive samples had increased number of lymphocytes and increased disease progression. These findings indicate that evaluation of telomerase activity may not only be a useful diagnostic test for lung cancer, but may also be a marker of disease aggressiveness for immune-associated lung diseases.

Biomarkers↗
PubMed1997

Telomerase activity is detected in pancreatic cancer but not in benign tumors.

Activation of telomerase and stabilization of telomeres are considered to be necessary for immortalization of human tumor cells. In the present study, telomerase activity was detected in 41 (95%) of 43 pancreatic cancer specimens but was detectable in none of 11 benign pancreatic tumors and only one of 3 pancreatitis samples. Low levels of telomerase activity were detected in 5 (14%) of 36 adjacent "normal" pancreatic tissues. These five telomerase-positive "normal" specimens were obtained from patients that also had pancreatic cancer and may reflect occult microinvasion. Telomerase activity was examined in 12 ex vivo brushing samples of the pancreatic duct, and 8 of 8 with pancreatic cancer had detectable telomerase activity, whereas 0 of 4 of benign lesions (cystadenoma and pancreatitis) did. These findings suggest that telomerase activity in cells derived from pancreatic ducts may be useful in the diagnosis of cancer and that telomerase activity may be a critical or rate-limiting step in pancreatic carcinogenesis.

Chronic Disease↗
PubMed1997

Telomerase activity in neuroblastoma: is it a prognostic indicator of clinical behaviour?

Neuroblastomas show remarkable biological heterogeneity, resulting in favourable prognosis or unfavourable prognosis due to aggressive growth despite multimodal therapy. Recently, we proposed that aggressive tumours express telomerase at a high level while the favourable tumours lack or have low telomerase expression. To evaluate the correlation between telomerase activity and other biological characteristics reported as prognostic markers (MYCN gene amplification, loss of heterogeneity (LOH) in the short arm of chromosome 1, trk-A expression, Ha-ras p21 expression, and DNA ploidy), we investigated these biological features in 105 untreated neuroblastomas. In these cases, 23 showed high telomerase activity, 78 showed low activity, and telomerase activity was undetectable in 4 cases. Most tumours with genetic alterations (MYCN amplification or 1p32 LOH) showed high telomerase activity. Most tumours with low or undetectable activity were aneuploid, and showed trk-A and Ha-ras expression. Three of the four tumours with undetectable telomerase activity regressed. In 2 of the tumours with low telomerase activity, the residual tumours maturated and showed repression of telomerase activity. Thus, the level of telomerase activity correlated with other genetic alterations and/or gene expression and may be a useful prognostic indicator in neuroblastoma.

Age Factors↗
PubMed1997

Effects of neutrophil elastase inhibitor on bleomycin-induced pulmonary fibrosis in mice.

Neutrophils play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). To elucidate the possible involvement of neutrophil elastase (NE) in pulmonary fibrosis, we investigated the efficacy of a new specific NE inhibitor (ONO-5046 Na) in a murine model of human IPF, bleomycin-induced pulmonary fibrosis. Bronchoalveolar lavage (BAL) and histopathological analysis were performed on bleomycin-treated mice (group A), bleomycin and ONO-5046 Na-treated mice (group B), and saline control groups at 1, 15, and 29 d after the end of bleomycin treatment. At 29 d, multifocal fibrosis was observed in group A, whereas no fibrotic regions were observed in group B. Interleukin-1 beta and macrophage inflammatory protein-2 mRNA levels in BAL cells on day 1, and platelet-derived growth factor-A and insulin-like growth factor-1 mRNA levels on days 1 and 15, were significantly lower in group B than in group A. Thus, we demonstrated an inhibitory effect of ONO-5046. Na on pulmonary fibrosis in mice, indicating the involvement of NE in the pathogenesis of pulmonary fibrosis. We propose that this effect might be related to suppressed expression of particular cytokines in alveolar macrophages and that this specific NE inhibitor could be a novel therapeutic agent for IPF.

Animals↗
PubMed1997

[Telomere and telomerase in human cancer].

Human somatic cells gradually lose their telomeric repeats each cell division, and when they become critically shortened, stop dividing. On the other hand, in immortal cancer cells and germline cells, telomerase, a ribonucleoprotein which can compensate for the loss of telomeric repeats synthesizing telomeric DNA onto chromosomal ends, is activated and the telomere lengths are stabilized. Thus, telomere length and telomerase activity are believed to be characteristic indicators of cell proliferation and cell immortality, and inhibition of telomerase activity is expected to be a new strategy of anti-cancer therapy.

Antineoplastic Agents↗
PubMed1996

Telomerase activity in human breast tumors.

BACKGROUND: The activity of the ribonucleoprotein enzyme telomerase is not detected in normal somatic cells; thus, with each cell division, the ends of chromosomes consisting of the telomeric repeats TTAGGG progressively erode. The current model gaining support is that telomerase activity in germline and immortal cells maintains telomere length and thus compensates for the "end-replication problem." PURPOSE: Our objective was to determine when telomerase activity is reactivated in the progression to malignant breast cancer and if knowledge of telomerase activity may be an indicator for the diagnosis and potential treatment of breast cancer. METHODS: Using a polymerase chain reaction-based telomerase activity assay, we examined telomerase activity in 140 breast cancer specimens (from 140 patients), four phyllodes tumors (from four patients), 38 noncancerous lesions (20 fibroadenomas, 17 fibrocystic diseases, one gynecomastia; from 38 patients), and 55 adjacent noncancerous mammary tissues (from 55 of the 140 breast cancer patients). In addition, 33 fine-needle-aspirated breast samples (from 33 patients) were analyzed. RESULTS: Among surgically resected samples, telomerase activity was detected in 130 (93%) of 140 breast cancers. Telomerase activity was detected in 68% of stage I primary breast cancers, in 73% of cancers smaller than 20 mm, and in 81% of axillary lymph node-negative cancers. Moreover, the activity was detected in more than 95% of advanced stage tumors but in only two (4%) of 55 adjacent noncancerous tissues. While telomerase activity was not detected in any of 17 specimens of fibrocystic disease, surprisingly low levels of telomerase activity were detected in nine (45%) of 20 fibroadenomas. Among samples obtained by fine-needle aspiration, 14 (100%) of 14 patients whose fine-needle-aspirated specimen contained telomerase activity and who subsequently underwent surgery were confirmed to have breast cancer. Multivariate analysis of 125 specimens from patients for whom data were available on age at surgery, stage of disease, tumor size, lymph node status tumor histology, and menopausal status indicated that stage classification exhibited the strongest association with telomerase activity (for stage I versus stages II-IV: odds ratio = 1.0 versus 73.4; 95% confidence interval = 2.0-959.0; P = .02). CONCLUSION: Telomerase activity was detected in more than 95% of advanced stage breast cancers. It was absent in 19%-32% of less advanced cancers. Since a determination of any association between telomerase activity and patient survival is not possible at the present time, it remains to be determined whether lack of telomerase activity predicts for favorable outcome.

Adult↗
PubMed1996

Telomere shortening in peripheral blood cells was related with aging but not with white blood cell count.

Telomeres in somatic cells are progressively shortened with aging. We investigated the relationship between the telomere length and other factors which may affect the frequency of cell divisions, in peripheral blood cells. Shortening of telomeric repeats was correlated with aging (p < 0.0001), but not with white blood cell count, neutrophil count, and smoking habit. Not only the number of cell divisions, but also some other factors, such as upregulation level of telomerase activity concomitant with the cell division in hematopoietic progenitor cells, might affect the length of telomeric repeats in blood cells.

Adult↗
PubMed1996

Specific growth inhibition of small-cell lung cancer cells by adenovirus vector expressing antisense c-kit transcripts.

Antisense methods to control aberrant gene expression have been investigated as therapeutic strategies. A proto-oncogene c-kit, which encodes a transmembrane tyrosine kinase, is overexpressed in some malignancies, including small-cell lung cancer (SCLC), and is thought to be involved in their pathogenesis. To test the feasibility of using adenovirus vectors for antisense strategies and to target c-kit in SCLC therapy, we constructed replication-deficient recombinant adenovirus vectors which express fragments of c-kit transcripts in antisense (Ad.kitAS) or sense orientation (Ad.kitS: control). In vitro infection of SBC-1 cells, which are c-Kit protein-producing SCLC cells, by these vectors resulted in the expression of artificial c-kit transcripts. The Ad.kitAS-infected SBC-1 cells showed reductions in the amount of c-Kit protein. As expected, at 10 days after infection (1 multiplicity of infection), Ad.kitAS-infected SBC-1 cells showed approximately 40% growth inhibition compared to uninfected or Ad.kitS-infected cells in vitro. Such a significant growth inhibition by Ad.kitAS was not induced in SBC-5 cells, which are SCLC cells producing no c-Kit protein. These results demonstrate the usefulness of adenovirus vectors in antisense strategies, and the feasibility of targeting c-kit in the therapy of c-Kit-producing SCLC.

Adenoviridae↗
PubMed1996

Detection of p53 gene mutations in cytopathology and biopsy specimens from patients with lung cancer.

In order to ascertain the feasibility of detecting p53 gene mutations in patients with lung cancer in a nonsurgical diagnostic setting before starting treatment, we screened for p53 gene mutations in tumor specimens obtained using diagnostic methods such as fiberoptic bronchoscopy, thoracentesis, and percutaneous needle aspiration. We examined 206 specimens from 66 patients diagnosed with primary lung cancer at Hiroshima University Hospital between October 1991 and July 1993 using the polymerase chain reaction/denaturing gradient gel electrophoresis technique. p53 gene mutations were found in 64 of 159 (40%) cytologically positive specimens, but in none of 47 cytologically negative specimens. The PCR-based assay did not increase the sensitivity of the cytopathologic examination in detecting malignant cells. The type and location of the p53 gene mutation was the same in cytologically positive specimens obtained by different methods, but from the same patient. Of the 66 patients, p53 gene mutations were found in 27 (41%) at the time of the first nonsurgical diagnostic examination: 7 of 12 (58%) with small cell carcinoma, 9 of 20 (45%) with squamous cell carcinoma, and 11 of 34 (32%) with adenocarcinoma of the lung. The incidence of p53 gene mutation for each histologic subtype was comparable to previously published data examining surgically and/or autopsy-obtained specimens. These results indicate that detection of p53 gene mutations in a nonsurgical, diagnostic setting is feasible. This technique will make it possible to assess the significance of p53 gene mutations in relation to survival and response to therapy before starting treatment, in future prospective studies.

Adenocarcinoma↗
PubMed1996

Former poison gas workers and cancer: incidence and inhibition of tumor formation by treatment with biological response modifier N-CWS.

Mustard gas is known to have mutagenic and carcinogenic effects on animal and human cells. In this report, 1,632 male Japanese who worked in poison gas factories at some time between the years 1927 and 1945 were studied to determine comparative risk for development of cancer, the reference population being data on Japanese males overall. The standardized mortality ratio (SMR) for lung cancer in workers directly and indirectly involved in the production of mustard gas was significantly elevated. In addition, SMR for lung cancer in worker who had worked for more than 5 years was also significantly elevated. Thus, poison gas workers who had engaged in the production of mustard gas or related work for more than 5 years are a high-risk group for lung cancer. Under the cancer preventive program, Nocardia rubra cell-wall skeleton (N-CWS) was administered to 146 former poison gas workers. During a 4.5 year observation period, development of cancers was found in 7 treated workers and 17 untreated controls. After elimination of the influence of smoking level, a significant suppression of development of cancers was noted in the N-CWS-treated workers as compared to the untreated controls. Although the molecular mechanisms of carcinogenesis in former poison gas workers remains unclear, our study proposes the possible effect of biological response modifiers in the prevention of cancer development in high-risk human subjects.

Arsenicals↗
PubMed1996

Increased expression of platelet-derived growth factor A and insulin-like growth factor-I in BAL cells during the development of bleomycin-induced pulmonary fibrosis in mice.

Current concepts suggest that macrophages may play a central role in pulmonary fibrosis by virtue of their ability to release a variety of cytokines. In this study, the expression of interleukin (IL)-1 alpha and beta, platelet-derived growth factor (PDGF) A and B, and insulin-like growth factor (IGF) I in BAL cells, which may be involved in fibroblast proliferation, was investigated in murine bleomycin (BLM)-induced pulmonary fibrosis. BAL cells were obtained at 1, 15, and 29 days from Institute for Cancer Research mice after 10 days of intraperitoneal administration of BLM. The relative amounts of cytokine messenger RNA (mRNA) were evaluated by the reverse transcription-polymerase chain reaction method, which simultaneously amplified complementary DNA for cytokines and beta-actin as an internal control. The level of IL-1 beta mRNA in BLM-treated mice was increased 4.5-fold compared with that in saline solution-treated (control) mice 1 day after treatment, while no significant differences were observed between the two groups at 15 and 29 days. The mRNAs of PDGF-A and IGF-I in BLM-treated mice were sustained at levels eightfold and threefold to fourfold, respectively, those of controls over 4 weeks. No significant differences were noted in IL-1 alpha and PDGF-B expression between the two groups. We conclude that IL-1 beta released from macrophages may be important in the early phase of inflammatory responses and that PDGF-A and IGF-I may play important roles in the development of BLM-induced pulmonary fibrosis.

Animals↗
PubMed1996

Increased expression of tumor necrosis factor-alpha, interleukin-6, platelet-derived growth factor-B and granulocyte-macrophage colony-stimulating factor mRNA in cells of bronchoalveolar lavage fluids from patients with sarcoidosis.

Cytokines released from activated alveolar macrophages and T-lymphocytes affect the accumulation of monocyte-macrophage-lineage cells and therefore play an important role in the formation of sarcoid granuloma. Although it is likely that certain monokines and lymphokines are involved in the development of sarcoid granulomas, the evidence for this is not unequivocal. In an attempt to clear critical cytokines in the development and maintenance of sarcoid granuloma, we have measured the level of seven cytokine mRNA (TNF-alpha, IL-6, IL-8, TGF-beta, PDGF-B, IFN-gamma, and GM-CSF) in cells obtained by BAL from sarcoidosis patients and normal subjects. To detect cytokine mRNA, we employed a reverse transcription-polymerase chain reaction. We report that the levels of TNF-alpha, IL-6, PDGF-B and GM-CSF mRNA were significantly increased in BAL cells from the patients with pulmonary sarcoidosis compared to controls. No significant differences were observed in the mRNA expression of IL-8, TGF-beta and IFN-gamma. A significant correlation of the expression of the mRNA levels of seven cytokines in the same patients with sarcoidosis was observed between IL-8 and TNF-alpha, PDGF-B, and IL-6, IL-8 and IL-6 and TFN-alpha and PDGF-B and IL-8. This finding indicates that at least these four cytokines are involved in the cytokine network at the local alveolar site of chronic granulomatous inflammation. This study adds a report to the literature that supports a role for cytokine, TNF-alpha, IL-6, PDGF and GM-CSF in particular, in the promotion and maintenance of sarcoid granulomatous inflammation.

Adult↗
PubMed1996

Differential display of messenger RNA expressed in bronchoalveolar lavage cells in pulmonary sarcoidosis patients.

Sarcoidosis is a systemic granulomatous disease of unknown origin. To clarify its pathogenesis, we searched for known or unknown genes which are specifically expressed in sarcoidosis. Bronchoalveolar lavage (BAL) cells from 18 patients with sarcoidosis and 8 patients with various lung diseases were analyzed by differential display method. mRNA was extracted from BAL cells and reverse transcribed with 12 kinds of anchored primer, which theoretically cover all mRNAs, followed by polymerase chain reaction (PCR) with the anchored primer and a 10-mer arbitrary primer. PCR products were displayed on a polyacrylamide gel and fragments showing characteristic alterations in intensity between sarcoidosis and other patients were extracted, sequenced, and compared against Genbank and EMBL DNA data bases. One fragment was detected with specifically increased intensity and another disappeared in patients with sarcoidosis. These fragments were likely derived from unknown genes. CD44 and tumor necrosis factor (TNF-alpha) cDNA sequences were also detected as fragments commonly expressed in sarcoidosis. The cloned fragments with specifically increased or decreased intensity in sarcoidosis may provide important information on the pathogenesis of sarcoidosis, and the display pattern implies the potential usefulness of this method as a tool for diagnosis of the disease.

Adolescent↗
PubMed1995

Activation of telomerase in human lymphocytes and hematopoietic progenitor cells.

This is the first report describing up-regulation of telomerase activity in human normal cells. Telomerase, a ribonucleoprotein enzyme, has been thought to be involved in maintaining telomere length stability in germline and most cancer cells, but not in normal cells. However, in the present study, we demonstrate that telomerase activity is detectable at low levels in normal human T and B cells, increases by in vitro mitogenic stimulation, increases in hematopoietic progenitor cells upon their proliferation and differentiation, and decreases with aging. Understanding the regulation of telomerase activity in normal cells may provide important insights not only into the mechanisms of normal cellular senescence but also into the mechanisms of telomerase activity deregulation as part of cancer development.

Adolescent↗