Issei Tachibana

Overexpression of the TGFbeta-regulated zinc finger encoding gene, TIEG, induces apoptosis in pancreatic epithelial cells.

Members of the TGFbeta family of peptides exert antiproliferative effects and induce apoptosis in epithelial cell populations. In the exocrine pancreas, these peptides not only regulate normal cell growth, but alterations in these pathways have been associated with neoplastic transformation. Therefore, the identification of molecules that regulate exocrine pancreatic cell proliferation and apoptotic cell death in response to TGFbeta peptides is necessary for a better understanding of normal morphogenesis as well as carcinogenesis of the pancreas. In this study, we have characterized the expression and function in exocrine pancreatic epithelial cells of the TGFbeta-inducible early gene (TIEG), a Krüppel-like zinc finger transcription factor encoding gene previously isolated from mesodermally derived osteoblastic cells. We demonstrate that this gene is expressed in both acinar and ductular epithelial cell populations from the exocrine pancreas. In addition, we show that the expression of TIEG is regulated by TGFbeta1 as an early response gene in pancreatic epithelial cell lines. Moreover, overexpression of TIEG in the TGFbeta-sensitive epithelial cell line PANC1 is sufficient to induce apoptosis. Together, these results support a role for TIEG in linking TGFbeta-mediated signaling cascades to the regulation of pancreatic epithelial cell growth.

Mapping of the chromosome 19 q-arm glioma tumor suppressor gene using fluorescence in situ hybridization and novel microsatellite markers

Allelic loss of chromosome arm 19q is a frequent event in human diffuse glioma, suggesting the presence of a tumor suppressor gene. Previous loss of heterozygosity (LOH) analyses have mapped this gene to a 1.4-megabase interval, between the genetic markers D19S412 and STD. Further narrowing of this interval has been limited by the resolution of mapped polymorphic markers. In the present study, we have used genomic clones mapped to 19q as fluorescence in situ hybridization (FISH) probes to map the breakpoints of 13 gliomas with 19q13.3 deletion boundaries. In addition, we have developed three new polymorphic microsatellite markers (D19S1180, D19S1181, and D19S1182) that map between D19S412 and STD and have used these new markers to identify two gliomas with small deletions between the D19S412 and STD markers. Collectively, these data suggest that the region of common deletion may be as narrow as 150 kb and should facilitate future efforts to identify the glioma 19q tumor suppressor gene.

Invasive cancer and survival of intraductal papillary mucinous tumors of the pancreas

OBJECTIVES:Intraductal papillary mucinous tumor (IPMT) is frequently associated with pancreatic cancer. We hypothesized that IPMT progresses to invasive cancer with K-ras mutations as an early event, and that invasive cancer affects survival. We compared survival after resection and determined whether K-ras mutations predicted survival in IPMT patients without or with invasive cancer.METHODS:Records of 47 patients with IPMT who were seen between 1983 and 1998 were reviewed retrospectively in 15 cases and prospectively in 32. All histological material was reviewed to confirm the diagnosis of IPMT and to assess invasion. Kaplan-Meier survival curves were analyzed by the log-rank test. The χ2 test was used for differences in K-ras between groups.RESULTS:There were 30 men and 17 women, with a mean age of 65 yr (range 36–90 yr). Of the patients, 26 had IPMT without invasive cancer and 19 had IPMT with invasion. Tissue diagnosis was available in 45 patients. K-ras was analyzed in 40 patients. Mutations were present in 15 of 23 patients (65%) without invasive cancer and in 14 of 17 patients (82%) with invasive cancer (p = ns). At 2.5 yr, the overall cumulative survival of IPMT patients without invasive cancer was 94% compared to 24% of patients with invasive cancer (p < 0.001). The 5-yr survival of IPMT patients without invasive cancer was 94%. K-ras mutations did not correlate with survival.CONCLUSIONS:Invasive cancer in IPMT reduces the 2.5-yr survival after surgery from 93% to 24%. K-ras mutations occur before invasive cancer, and do not predict postoperative survival.

Investigation of germline PTEN, p53, p16INK4A/p14ARF, and CDK4 alterations in familial glioma

Epidemiological studies suggest that some familial aggregations of glioma may be due to inherited predisposition. Many genes involved in familial cancers are frequently altered in the corresponding sporadic forms. We have investigated several genes known to be altered in sporadic gliomas for their potential contribution to familial glioma. Fifteen glioma patients with a family history of brain tumors were identified through the Mayo Clinic Department of Neurology (nine diffuse astrocytomas, two oligodendrogliomas, two mixed oligoastrocytomas, one pilocytic astrocytoma, and one pineal glioma). Eleven of the propositi had one or more first degree relative with a glioma. Lymphocyte DNA was derived from each of the patients and analyzed by polymerase chain reaction (PCR) and direct sequencing of the PTEN, p53, p16(INK4A)/p14(ARF), and CDK4 genes. In addition, fluorescence in situ hybridization (FISH) was performed on EBV-transformed lymphocytes from each affected individual to detect germline copy number of the p16(INK4A)/p14(ARF) tumor suppressor region. A p53 germline point mutation was identified in one family with some findings of Li-Fraumeni syndrome, and a hemizygous germline deletion of the p16(INK4A)/p14(ARF) tumor suppressor region was demonstrated by FISH in a family with history of both astrocytoma and melanoma. Thus, whereas germ-line mutations of PTEN, p53, p16(INK4A)/p14(ARF), and CDK4 are not common events in familial glioma, outside of familial cancer syndromes, point mutations of p53 and hemizygous deletions and other rearrangements of the p16(INK4A)/p14(ARF) tumor suppressor region may account for a subset of familial glioma cases. Collectively, these data lend genetic support to the heritable nature of some cases of glioma.

Augmented Cardiac Cardiotrophin-1 in Experimental Congestive Heart Failure

BACKGROUND Cardiotrophin-1 (CT-1) is a potent hypertrophic factor discovered by coupling expression cloning in a mouse embryonic stem cell-based model of cardiogenesis. METHODS AND RESULTS The present study was designed to investigate the potential activation of atrial and ventricular CT-1 expression in pacing-induced experimental congestive heart failure (CHF) and its relationship to left ventricular hypertrophy by the method of Northern blot analysis and immunohistochemistry. We used a canine model of pacing-induced experimental CHF based on hemodynamic and neurohumoral characteristics that closely mimic human dilated cardiomyopathy. Northern blot analysis demonstrated that CT-1 gene expression was present in normal atrium and ventricle and was increased in CHF hearts. There was a positive correlation between ventricular CT-1 mRNA and left ventricular mass index. Immunohistochemistry revealed positive immunostaining in the atrial and ventricular cardiomyocytes from both normal and CHF hearts. CT-1 immunoreactivity was more intense in the atrium and ventricle from CHF hearts than in normal hearts. CONCLUSIONS The present study demonstrates that both atrium and ventricle synthesize CT-1 and that cardiac production of CT-1 is augmented in a canine model of experimental CHF. This study also demonstrates that ventricular CT-1 mRNA correlates with left ventricular hypertrophy, suggesting that CT-1 plays an important role in the structural remodeling that characterizes CHF.

Ventricular cardiotrophin-1 activation precedes BNP in experimental heart failure.

Both cardiotrophin-1 (CT-1) and B-type or brain natriuretic peptide (BNP) are activated by cardiomyocyte stretch, and gene expression of CT-1 and BNP are augmented in the heart in experimental and human congestive heart failure (CHF). The goal of this study was to define cardiac gene expression of CT-1 and BNP by Northern blot analysis in normal (n=5), early left ventricular dysfunction (ELVD, n=5) and overt CHF dogs (n=5), in which ventricular function is progressively decreased. CT-1 mRNA was detected in both atria and ventricles in normal dogs. Ventricular CT-1 mRNA production increased in ELVD, and it further increased in overt CHF. Ventricular BNP mRNA remained below or at the limit of detection in normal and ELVD models, and it markedly increased in overt CHF. This study reports differential regulation of gene expression of CT-1 and BNP in the heart during the progression of CHF, and demonstrates that ventricular CT-1 gene activation precedes ventricular BNP gene activation.

The human glia maturation factor-gamma gene: genomic structure and mutation analysis in gliomas with chromosome 19q loss.

ABSTRACT Human glia maturation factor-gamma (hGMF-γ) is a recently identified gene that may be involved in glial differentiation, neural regeneration, and inhibition of tumor cell proliferation. The gene maps to the long arm of chromosome 19 at band q13.2, a region that is frequently deleted in human malignant gliomas and is thus suspected to harbor a glioma tumor suppressor gene. Given the putative role of hGMF-γ in cell differentiation and proliferation and its localization to chromosome 19q13, this gene is an interesting candidate for the chromosome 19q glioma tumor suppressor gene. To evaluate this possibility, we determined the genomic structure of human hGMF-γ and performed mutation screening in a series of 41 gliomas with and without allelic loss of chromosome 19q. Mutations were not detected, which suggests that hGMF-γ is not the chromosome 19q glioma suppressor gene. However, the elucidation of the genomic structure of hGMF-γ may prove useful in future investigations of hGMF-γ in the normal adult and developing human nervous system.