Does Helicobacter pylori eradication depend on the period of amoxicillin treatment? A retrospective study

In this study, the effect of different periods of amoxicillin (AMPC) treatment on the eradication rate of Helicobacter pylori in 173 patients with peptic ulcers (gastric ulcer, 109; duodenal ulcer, 64) was investigated. AMPC (1.5 g/day) was administered for 2, 4, or 6 weeks with omeprazole (20mg/day) and plaunotol (240mg/day), a mucoprotective drug, for 8 weeks. The H. pylori eradication rate was 46.7% for 2 weeks' treatment, 83.4% for 4 weeks' treatment, and 100% for 6 weeks' treatment. The eradication rate had a good correlation with the period of AMPC treatment. The healing rates of peptic ulcer at 4 and 8 weeks were 93.3% and 100%, respectively, in the 2-week group, 98.0% and 99.3% in the 4-week group, and 85.7% and 100% in the 6-week group. The recurrence rate of gastric and duodenal ulcers was 3.5% and 0% respectively, in the patients in whom H. pylori was eradicated and 30.0% and 40%, respectively, in the patients in whom H. pylori was not eradicated for 12 months after the H. pylori eradication treatment. Adverse effects of this regimen were observed in 5 (2.9%) of the 173 patients. Diarrhea was observed in 3 patients and eruption in 2. These adverse effects disappeared within a few days after only AMPC was withdrawn. Therefore, these may be caused by AMPC. The eradication rate of H. pylori depends on the period of AMPC treatment. This regiment, AMPC (1.5g/day) + omeprazole (20mg/day) + plaunotol (240mg/day), is safe and well tolerated for eradication of H. pylori.

Postgraduate education in medical ethics in Japan

The objective of this paper was to investigate what kind of postgraduate education in medical ethics medical residents in Japan receive and what they want for ethical education and guidelines. Sixteen teaching hospitals that provide a general internal medicine residency programme in Japan were used (145 medical residents working at the departments of general internal medicine). A total of 114 residents participated in our survey, yielding a response rate of 79%. Of these, 28% received education in medical ethics more than once a month; 24% were offered it only when ethical problems were involved in actual patient care; and 18% answered that opportunities were very rare and sporadic. A full 30% had received no education in medical ethics at all. Many residents (71%) learned medical ethics from individual supervising doctors. A majority of the residents had been taught about informed consent (79%) and doctor-patient relationships (54%); 46% had learned about the appropriateness of truth telling and of ethical decisions regarding withholding and withdrawing a life-sustaining treatment, respectively. A total of 85 residents (75%) wanted to have more comprehensive education in medical ethics, 13% could not decide, and 12% did not want it. Many (66%) thought that both doctors and ethical philosophers should jointly teach medical ethics in postgraduate residency programmes. The results suggest that many residents desire more comprehensive and interdisciplinary education in medical ethics and educators in Japan should aim to develop education programmes to meet these desires.

A functional role for death proteases in s-Myc- and c-Myc-mediated apoptosis

Upon activation, cell surface death receptors, Fas/APO-1/CD95 and tumor necrosis factor receptor-1 (TNFR-1), are attached to cytosolic adaptor proteins, which in turn recruit caspase-8 (MACH/FLICE/Mch5) to activate the interleukin-1 beta-converting enzyme (ICE)/CED-3 family protease (caspase) cascade. However, it remains unknown whether these apoptotic proteases are generally involved in apoptosis triggered by other stimuli such as Myc and p53. In this study, we provide lines of evidence that a death protease cascade consisting of caspases and serine proteases plays an essential role in Myc-mediated apoptosis. When Rat-1 fibroblasts stably expressing either s-Myc or c-Myc were induced to undergo apoptosis by serum deprivation, a caspase-3 (CPP32)-like protease activity that cleaves a specific peptide substrate, Ac-DEVD-MCA, appeared in the cell lysates. Induction of s-Myc- and c-Myc-mediated apoptotic cell death was effectively prevented by caspase inhibitors such as Z-Asp-CH2-DCB and Ac-DEVD-CHO. Furthermore, exposing the cells to a serine protease inhibitor, 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF), also significantly inhibited s-Myc- and c-Myc-mediated apoptosis and the appearance of the caspase-3-like protease activity in vivo. However, AEBSF did not directly inhibit caspase-3-like protease activity in the apoptotic cell lysates in vitro. Together, these results indicate that caspase-3-like proteases play a critical role in both s-Myc- and c-Myc-mediated apoptosis and that caspase-3-like proteases function downstream of the AEBSF-sensitive step in the signaling pathway of Myc-mediated apoptosis.

Caspase-dependent apoptosis of COS-7 cells induced by Bax overexpression: differential effects of Bcl-2 and Bcl-xL on Bax-induced caspase activation and apoptosis

Bcl-2 family proteins and ICE/CED-3 family proteases (caspases) are regarded as the basic regulators of apoptotic cell death. They are evolutionarily conserved and implicated in a variety of apoptosis. However, the precise mechanism by which these two families interact to regulate cell death is not yet known. In this study, we found that the overexpression of the Bcl-2 family member Bax induced apoptotic cell death in COS-7 cells through the activation of CPP32 (caspase-3)-like proteases that cleaved the DEVD tetrapeptide. This apoptotic cell death was suppressed by the viral proteins CrmA and p35, as well as by the chemically synthesized caspase inhibitors Z-Asp-CH2-DCB and zVAD-fmk. We also found that the Bax-induced apoptosis of COS-7 cells was suppressed by Bcl-xL and Bcl-2, though both Bcl-xL and Bcl-2 similarly prevented etoposide-induced apoptosis in COS-7 cells. In addition, Bcl-xL inhibited the activation of caspase-3-like proteases accompanying Bax-induced COS-7 cell death but Bcl-2 did not. These results indicate that the caspase activation is essential for Bax-induced apoptosis, and that the ability of Bcl-2 and Bcl-xL to prevent the Bax-induced caspase activation and apoptosis in COS-7 cells could be differentially regulated. Our results also suggest that Bcl-2 family proteins function upstream of caspase activation and control apoptosis through the regulation of caspase activity.

Medical decisions concerning the end of life: a discussion with Japanese physicians

OBJECTIVES

Life-sustaining treatment at the end of life gives rise to many ethical problems in Japan. Recent surveys of Japanese physicians suggested that they tend to treat terminally ill patients aggressively. We studied why Japanese physicians were reluctant to withhold or withdraw life-support from terminally ill patients and what affected their decisions.

DESIGN AND PARTICIPANTS

A qualitative study design was employed, using a focus group interview with seven physicians, to gain an in-depth understanding of attitudes and rationales in Japan regarding medical care at the end of life.

RESULTS

Analysis revealed that physicians and patients' family members usually make decisions about life-sustaining treatment, while the patients' wishes are unavailable or not taken into account. Both physicians and family members tend to consider withholding or withdrawing life-sustaining treatment as abandonment or even killing. The strongest reason to start cardiopulmonary resuscitation- and to continue it until patients' family members arrive-seems to be the family members' desire to be at the bedside at the time of death. All physicians participating in our study regarded advance directives that provide information as to patients' wishes about life-sustaining treatment desirable. All expressed concern, however, that it would be difficult to forego or discontinue life-support based on a patient's advance directive, particularly when the patient's family opposed the directive.

CONCLUSION

Our group interview suggested several possible barriers to death with dignity and the appropriate use of advance directives in Japan. Further qualitative and quantitative research in this regard is needed.

Pim-1 kinase stimulates c-Myc-mediated death signaling upstream of caspase-3 (CPP32)-like protease activation

Pim-1 oncoprotein is a serine/threonine kinase that can closely cooperate with c-Myc in lymphomagenesis, as does Bcl-2. Although the molecular mechanism of this cooperative transformation remains unknown, it is speculated that, similar to Bcl-2, Pim-1 contributes to transformation by inhibiting apoptosis. In this study, therefore, we examined the effect of Pim-1 expression on c-Myc-mediated apoptosis of Rat-1 fibroblasts triggered by serum deprivation. Our results showed that, rather than inhibiting apoptosis, Pim-1 expression stimulated c-Myc-mediated apoptosis in Rat-1 fibroblasts. Pim-1 stimulated c-Myc-mediated apoptosis through an enhancement of the c-Myc-mediated activation of caspase-3 (CPP32)-like proteases, since the suppression of this activity by a specific caspase inhibitor abolished the apoptosis stimulation by Pim-1. A kinase-defective Pim-1 mutant failed to stimulate c-Myc-mediated apoptosis, and Pim-1 expression alone in the absence of c-Myc overexpression did not induce apoptosis of serum-deprived Rat-1 cells, indicating that the kinase activity of Pim-1 and the activated c-Myc signaling pathway were required for apoptosis stimulation by Pim-1. Together, these results suggest that Pim-1 oncoprotein stimulates as a serine/threonine kinase the death signaling elicited by c-Myc at a step upstream of caspase-3-like protease activation in Rat-1 fibroblasts. Our results also suggest that Pim-1 kinase might function cooperatively with c-Myc through the phosphorylation of a factor(s) which regulates the common signaling pathway involved in c-Myc-mediated apoptosis and transformation.

Increased expression of midkine during the progression of human astrocytomas

Midkine (MK), a member of a new family of neurotrophic and angiogenic growth factors whose expression is developmentally regulated, is produced in fetal astrocytes. Malignant astrocytomas, one of the most neovascularized tumors, are derived from astrocytes. There has been no investigation of the expression of MK in human astrocytic tumors. To determine if increased levels of MK expression correlate with the progression of human astrocytomas, we examined surgical specimens of astrocytic tumors of various grades using Northern and Western blotting. MK mRNA and protein expression levels were higher in high-grade astrocytomas (anaplastic astrocytomas and glioblastomas) than in low-grade astrocytomas. As shown by in situ hybridization, MK mRNA expression was intense in a majority of glioblastoma cells but was weak in a small number of low-grade astrocytoma cells. These findings suggest that MK expression correlates with the malignant progression of astrocytomas. The aberrant MK expression in high-grade astrocytomas may underlie their rapid growth and well-vascularized features.

Application of antisense ribonucleic acid complementary to O6-methylguanine-deoxyribonucleic acid methyltransferase messenger ribonucleic acid for therapy of malignant gliomas

OBJECTIVE

A derivative of chloroethylnitrosoureas, 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU), is a drug of choice for the chemotherapy of human malignant brain tumors. However, the cytocidal effect of ACNU is effectively repressed through repair of ACNU-mediated deoxyribonucleic acid lesions by O6-methylguanine-deoxyribonucleic acid methyltransferase (MGMT). Because a variety of human tumors, including brain tumors, contain high levels of MGMT activity, we investigated the effect of antisense ribonucleic acid (RNA) complementary to MGMT messenger RNA on ACNU resistance in tumor cells.

METHODS

We established a stable ACNU-resistant clone, C6AR, from the rat glioma cell line C6 exposed to a stepwise increasing concentration of ACNU. We transfected a plasmid deoxyribonucleic acid-encoding antisense MGMT RNA under the control of the human metallothionein promoter into C6AR cells and determined the effect of the antisense RNA on ACNU resistance of tumor cells by a colony-forming efficiency assay.

RESULTS

C6AR cells expressed abundant MGMT messenger RNA, although the transcription level of the MGMT gene in parental C6 cells was below the lower limits of detection under the same assay conditions. ACNU resistance of C6AR cells was significantly repressed by transfected gene-dependent antisense MGMT RNA expression that resulted in decreased survival of the tumor cells.

CONCLUSION

ACNU resistance resulting from the expression of MGMT in rat glioma cells is significantly overcome by the expression of antisense MGMT RNA. This result suggests that the antisense MGMT RNA system might be a useful strategy for overcoming ACNU resistance in the treatment of intractable malignant gliomas.

Ultrasonographic evaluation of gastric emptying in normal children and children after pyloromyotomy

Gastric emptying in the fundus, body, and antrum of the stomach was evaluated by ultrasonography (US) in 41 control children aged 2 to 18 years and 30 patients aged 1 to 19 years who had undergone pyloromyotomy because of hypertrophic pyloric stenosis. The gastric emptying curve decreased in an exponential manner for both control children and patients, while there was no significant difference in gastric emptying time (GET) between control children and patients within any of the age groups. However, GET was faster for younger children in both groups. An X-ray contrast study of the stomach performed in 2 patients who showed markedly delayed GET showed delayed gastric emptying but no significant deformities of the prepylorus. Our results suggest that US is a reliable method of measuring GET in children.

Growth-associated protein GAP-43 detection in the neuronal somata following middle cerebral artery occlusion in the rat

We first detected growth-associated protein (GAP-43) immunoreactivity in the neuronal somata following middle cerebral artery occlusion in the rat. Four days after the middle cerebral artery occlusion, GAP-43 immunoreactivity was detected in some cortical neurons of the ischemic penumbra at the level of the hippocampus.

Thiol-independent DNA cleavage by a leinamycin degradation product

To understand the mechanism of action of a novel antitumor antibiotic leinamycin (1) which induces single-strand scission of DNA in the presence of thiol, the reaction of 1 with thiol in aqueous conditions was investigated. Two major degradation products were obtained from 1 in the presence of thiol. 2 was an inactive product, while 3 caused DNA cleavage in the absence of thiol. The DNA-cleaving activity of their synthetic derivatives indicates that the DNA alkylation and subsequent strand scission by leinamycin require the conversion of leinamycin to an electrophilic episulfonium species.

Proliferative activity of central neurocytoma: measurement of tumor volume doubling time, MIB-1 staining index and bromodeoxyuridine labeling index

Central neurocytoma is considered to be a benign intracranial neoplasm, but little is known about the biological behavior of this type of tumor. Proliferative activity of central neurocytoma was measured in 10 cases using MIB-1 staining for Ki-67 antigen. The MIB-1 staining value varied from < 0.1% to 5.6%, to indicating that some of these tumors have proliferative potential similar to that of anaplastic astrocytoma or malignant meningioma. The bromodeoxyuridine labeling index (BUdR LI, BrdU LI) was measured in 2 cases and the results correlated well with those of the MIB-1 analysis. Tumor volume doubling time (Td) measured in one case was 358 days which is similar to that of malignant meningioma. In one case, the MIB-1 value taken before and after 58 Gy of radiation treatment decreased markedly from 5.6% to 0.2%. The other 9 cases were also treated by radiation therapy (50-60 Gy) and no tumor recurrence was observed during follow-up periods ranging from 23 to 160 months. Another two patients with partially removed and 3 with subtotally removed tumors showing relatively high MIB-1 values might also have benefited from radiation therapy.

Synthesis and antitumor activity of duocarmycin derivatives: A-ring pyrrole compounds bearing cinnamoyl groups

A series of N-cinnamates of the A-ring pyrrole compound of duocarmycin were synthesized and evaluated for in vitro anticellular activity against HeLa S3 cells and in vivo antitumor activity against murine sarcoma 180 in mice. The 4'-methoxy- and 4'-BocNH-cinnamates exhibited strong in vitro anticellular activity among the synthesized compounds. The ortho substitution of the 4'-methoxycinnamate did not affect the anticellular activity and contributed to an enhancement of water solubility. Most of the 8-O-(N,N-dialkylcarbamoyl) derivatives of the 4'-methoxycinnamate displayed remarkably superior in vivo antitumor activity to duocarmycin A or B2. Moreover, it is noteworthy that these 8-O-(N,N-dialkylcarbamoyl) derivatives exhibited significant antitumor activity at wider range of doses as compared with the A-ring pyrrole derivatives having the trimethoxyindole skeleton in segment B.

Studies on duocarmycin SA and its derivatives

New duocarmycin SA derivatives have been synthesized and evaluated for in vitro anticellular activity against HeLa S3 cells, and in vivo antitumor activity against murine sarcoma 180 in mice. The results suggested that the N,N-dialkylcarbamoyl derivatives bearing the p-methoxy cinnamoyl group, which was prepared from duocarmycin SA, showed good in vivo antitumor activities superior to native duocarmycin SA.

Circulating matrix metalloproteinase-2 and tissue inhibitor of metalloproteinase-1 as serum markers of fibrosis in patients with chronic hepatitis C. Relationship to interferon response

BACKGROUND/AIMS/METHODS

The imbalance between matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) is considered to be an important determinant of extracellular matrix deposition and breakdown. We measured serum MMP-1, MMP-2, TIMP-1 and TIMP-2 levels using the respective one-step sandwich enzyme immunoassays in 98 patients with chronic hepatitis C treated with interferon beta to examine their clinical significance for assessment of liver histology and to determine whether they can be useful as predictors of the interferon response.

RESULTS

Serum TIMP-1 levels showed a positive correlation with the degree of fibrosis (r(s)=0.30, p= 0.004). Serum MMP-2 levels revealed positive relationships with the degree of periportal necrosis (r(s)= 0.32, p=0.002), the degree of fibrosis (r(s)=0.26, p= 0.01) and total score of histological activity index (r(s)=0.24, p=0.02). Serum MMP-2 levels were significantly higher in patients with no response than in those with sustained and transient response (p<0.01 and p<0.05, respectively), while serum MMP-1 levels did not differ among the three groups. Compared with the levels in sustained responders, the total amounts of serum TIMP-1 were significantly lower in transient responders and non-responders (p<0.01 and p<0.001, respectively). As for serum TIMP-2 levels, a significant decrease was found in transient responders and non-responders (p<0.01). The ratios of serum MMP-2 to TIMP-1 levels were significantly higher in transient responders and non-responders than in sustained responders (p<0.001, respectively) even when HCV RNA levels were low in patients with HCV genome subtype 1b or when the HCV genome subtype was 2a or 2b. Sustained response was never found in type 1b patients with ratios of serum MMP-2 to TIMP-1 levels of over 6.0. In logistic multivariate regression analysis, the ratios of serum MMP-2 to TIMP-1 level (p=0.0001), HCV genome subtype (p=0.005) and serum TIMP-2 level (p=0.03) were the independent predictors for sustained response, while serum MMP-2 level (p=0.0006) was the only predictor for no response.

CONCLUSIONS

Serum MMP-2 and TIMP-1 levels might be useful for estimating the degree of liver fibrosis. The ratio of serum MMP-2 to TIMP-1 levels may serve as a new predictor of interferon response in patients with chronic hepatitis C.

A rare case of hamartoma in the lateral ventricle: case report

BACKGROUND

Intraventricular manifestation of a hamartoma is an unusual clinical entity.

CASE DESCRIPTION

A 12-year-old girl was admitted with complaints of dizziness and head heaviness. Computed tomography and T1-weighted magnetic resonance imaging (MRI) demonstrated an isodensity or isointensity mass lesion with cystic component in the right lateral ventricle, which showed relatively high signal intensity on T2-weighted MRI and lacked contrast enhancement. Histopathologic examination on the surgically removed specimens using glial fibrillary acidic protein, Klüver-Barrera, Bodian stainings, bromouridine labeling index, and MIB-1 immunohistochemical staining confirmed that the tumor had glial and neuronal components and low proliferative potentiality.

CONCLUSION

This case is the first report of intraventricular hamartoma, although some reports on intracranial hamartoma located in areas other than the hypothalamus have been published. The radiologic findings, including relatively high signal intensity on T2-weighted MRI and absence of contrast enhancement, may be suggestive of the diagnosis of intraventricular hamartoma; however, the specific stainings for glial and neuronal cells and proliferative evaluation are essential to the precise diagnosis of hamartoma. Clinical manifestation of hamartoma in the ventricular system, though rare, should be kept in mind.

HIV and the primary care physician in Japan

Primary care physicians in Japan must provide comprehensive medical care and counseling for persons both infected with and at risk for HIV/AIDS. Despite existing activities and education programs, HIV case numbers continue to rise in Japan, and only a limited number of hospitals and physicians offer care to those with HIV/AIDS. Some doctors in Japan refuse to accept patients with HIV/AIDS because of the complex treatment often involved, prejudice regarding AIDS, and fear of transmission. Other impediments to effective treatment of HIV/AIDS in Japan include insufficient risk evaluation through outpatient services, lack of privacy, and restrictions and policies at medical facilities. If Japan's primary care physicians cannot participate in caring for those with HIV/AIDS, it will be impossible for every patient with HIV/AIDS to receive correct and adequate medical care. To enable primary care physicians to provide high-quality service and prevention counseling to those with HIV/AIDS, prejudice, fear, and logistic impediments must be eradicated. Comprehensive practice guidelines that protect patients' rights and privacy should be established immediately. The guidelines should direct primary care physicians toward a logical and proper approach to HIV/AIDS care by addressing fundamental treatment and effective prevention counseling as well as the social problems surrounding HIV/AIDS. In addition, research on the general knowledge level and prevalent attitudes among Japan's primary care physicians regarding HIV/AIDS would clarify which specific issues the guidelines should emphasize.

Disinfection of removable dentures using ozone

Over time, removable dentures tend to become unsanitary and emit unpleasant odors, and oral mucosa sometimes becomes inflamed or denture stomatitis is caused by denture plaque. Recently, various cleaning products designed to keep removable dentures sanitary have appeared on the market. It is known that denture plaque is mainly composed of Candida albicans (C. albicans), and that ozone seems to inhibit these micro-organisms. Accordingly, a denture cleaner using ozone bubbles (ozone concentration of about 10 ppm) was considered as clinically appropriate because of its strong disinfecting and deodorizing power, and high biological safeness. The effectiveness of this cleaner against C. albicans was investigated using. Results showed that C. albicans decreased to about 1/10 after 30 min and to 1/10(3) after 60 min.

Up-regulation of c-myc gene expression following focal ischemia in the rat brain

Changes in gene expression including that of c-fos occur following cerebral ischemia. Proto-oncogenes c-myc and s-myc and oncosuppressor gene p53 are known to induce apoptosis in some types of cells, whereas proto-oncogene bcl-2 inhibits apoptosis. Possible induction of mRNAs for c-myc, N-myc, s-myc, c-fos, p53 and bcl-2 was examined following focal ischemia in the rat anterior cortex, hippocampus, thalamus and cerebellum by Northern blot analysis. Animals were decapitated 1, 2, 6, 12, and 24 hours following the left middle cerebral artery (MCA) occlusion. In sham-operated control rats, the mRNAs for c-myc, N-myc, c-fos and p53 were present in the anterior cortex, hippocampus, thalamus on both sides, and in the cerebellum, whereas those for s-myc and bcl-2 were not. The c-myc gene expression was rapidly and markedly induced by the MCA occlusion in the ipsilateral anterior cortex, hippocampus and thalamus in a time-dependent manner. In these regions, the c-fos gene expression was also induced as early as 1 hour after the MCA occlusion. The p-53 mRNA was induced in the ipsilateral hippocampus at 24 hours after MCA occlusion. In contrast, mRNAs for N-myc, s-myc and bcl-2 were not induced following MCA occlusion. These results indicate a possibility that high-level expression of the c-myc gene may be involved in the ischemic cellular events including apoptosis.

Synthesis and antitumor activity of duocarmycin derivatives: modification of segment A of duocarmycin B2

Several A-ring pyrrole derivatives of duocarmycin B2 were synthesized effectively from the 3-hydroxy compounds by utilizing an interesting acid-catalyzed rearrangement, their anticellular activity was preliminarily evaluated by assays of growth inhibition of HeLa S3 cells (in vitro) and antitumor activity against murine sarcoma 180 (in vivo). The 8-O-N,N-dialkylcarbamoyl derivatives of the A-ring pyrrole compound showed remarkably potent in vivo antitumor activity, superior to that of duocarmycin B2. these derivatives were subjected to further biological evaluation. They exhibited potent antitumor activity toward murine solid tumors including M5076 sarcoma, B-16 melanoma and Colon 26 adenocarcinoma. Their most noteworthy feature was their efficacy against various human xenografts including LC-6 (lung), St-4 (stomach), and Co-3 (colon).

Regional distribution of heparin-binding epidermal growth factor-like growth factor mRNA and protein in adult rat forebrain

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a recently described member of the EGF family that binds to and stimulates phosphorylation of the EGF receptor (EGFR). In this study, we examined the cellular localization of HB-EGF gene transcripts and protein in adult rat forebrain. In situ hybridization studies showed that neurons in various regions, including cortex, hippocampus, and deep structures, express HB-EGF mRNA. Positively labeled cells were also present in white matter, which suggests that both neurons and glia express HB-EGF mRNA. Immunohistochemical studies with an antibody specific to proHB-EGF, a transmembrane form of HB-EGF, demonstrated ubiquitous immunoreactivity in neurons and glial cells in white matter. In view of the wide expression of its cognitive receptor, EGFR, in central nervous system neurons, our results suggest that HB-EGF is an endogenous ligand for EGFR in the central nervous system and may play an important role in physiological conditions.

Increased expression of schwannoma-derived growth factor (SDGF) mRNA in rat tumor cells: involvement of SDGF in the growth promotion of rat gliomas

Schwannoma-derived growth factor (SDGF) is a member of the epidermal growth factor (EGF) family, having mitogenic activity on rat astrocytes, fibroblasts and Schwann cells. The SDGF gene is significantly expressed in the newborn rat lung and in the adult rat sciatic nerve. However, except for one rat schwannoma cell line, from which SDGF and its cDNA were isolated, nothing is known about SDGF expression in established tumor cell lines. We examined the expression level of the SDGF gene in a variety of rat tumor cell lines by Northern blotting and found that it was increased in 11 of 25 established lines. The most abundant SDGF mRNA, which was about 50-fold higher than in the newborn rat lung, was expressed in rat liver adenoma dRLa74 cells. In rat glioma cell lines, such as C6, 9L and T9, and in the rat hepatoma dRLh84 and H411E cells, the SDGF expression level was about 10-fold higher than in the newborn rat lung. In 8 of 13 cell lines expressing SDGF mRNA, the EGF receptor (EGFR) gene, the product of which is regarded as a functional receptor of SDGF, was co-expressed. In addition, transfected gene-dependent anti-sense SDGF RNA expression under the control of the human metallothionein promoter significantly suppressed the in vitro growth as well as in vivo tumorigenicity of 9L glioma cells. Our results suggest that SDGF acts as an autocrine growth factor in the development and growth of rat tumors such as gliomas.