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Shigeki Sekine

Publications and source records attributed to Shigeki Sekine.

15 recordsLinked to original sources
PubMed2006

Hedgehog/Ras interactions regulate early stages of pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDA) constitutes a lethal disease that affects >30,000 people annually in the United States. Deregulation of Hedgehog signaling has been implicated in the pathogenesis of PDA. To gain insights into the role of the pathway during the distinct stages of pancreatic carcinogenesis, we established a mouse model in which Hedgehog signaling is activated specifically in the pancreatic epithelium. Transgenic mice survived to adulthood and developed undifferentiated carcinoma, indicating that epithelium-specific Hedgehog signaling is sufficient to drive pancreatic neoplasia but does not recapitulate human pancreatic carcinogenesis. In contrast, simultaneous activation of Ras and Hedgehog signaling caused extensive formation of pancreatic intraepithelial neoplasias, the earliest stages of human PDA tumorigenesis, and accelerated lethality. These results indicate the cooperation of Hedgehog and Ras signaling during the earliest stages of PDA formation. They also mark Hedgehog pathway components as relevant therapeutic targets for both early and advanced stages of pancreatic ductal neoplasia.

Animals↗
PubMed2006

Primary cilia deletion in pancreatic epithelial cells results in cyst formation and pancreatitis.

BACKGROUND & AIMS: Defects in cilia formation or function have been implicated in several human genetic diseases, including polycystic kidney disease (PKD), Bardet-Biedl syndrome, and primary ciliary dyskinesia. Pancreatic lesions are found in approximately 10% of PKD patients, suggesting a connection between cilia defects and pancreatic pathologies. Here, we investigate the role of cilia in pancreas formation and function by analyzing mice that lack cilia in pancreatic cells. METHODS: Using Cre/lox technology, we conditionally inactivated Kif3a, the gene encoding for a subunit of the kinesin-2 complex that is essential for cilia formation, in pancreatic epithelia. Kif3a mice were studied by immunohistochemical and biochemical methods to assess the morphology and differentiation status of pancreatic cells. RESULTS: Tissue-specific loss of Kif3a in pancreatic cells resulted in severe pancreatic abnormalities including acinar-to-ductal metaplasia, fibrosis, and lipomatosis. Ductal metaplasia appears to be due to expansion of ductal cells rather than transdifferentiation of acinar cells. Cyst formation, aberrant ductal morphology, and extensive fibrosis associated with severe adhesion to adjacent organs were commonly observed in aged Kif3a mutant mice. Deletion of Kif3a using different pancreas-specific Cre strains suggests that these pancreatic phenotypes might be caused by the absence of cilia in ductal cells. Activation of transforming growth factor beta and Mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK) pathways may play a role in these phenotypes. CONCLUSIONS: These results demonstrate that the absence of cilia in pancreatic cells produces pancreatic lesions that resemble those found in patients with chronic pancreatitis or cystic fibrosis.

Animals↗
PubMed2006

Liver-specific loss of beta-catenin blocks glutamine synthesis pathway activity and cytochrome p450 expression in mice.

There is accumulating evidence that Wnt/beta-catenin signaling is involved in the regulation of liver development and physiology. The presence of genetic alterations resulting in constitutive beta-catenin stabilization in human and murine liver tumors also implicates this pathway in hepatocyte proliferation. In the present study, we generated hepatocyte-specific beta-catenin knockout mice to explore the role of beta-catenin in liver function. Conditional knockout mice were born at the expected Mendelian ratio and developed normally to adulthood, indicating beta-catenin is dispensable for essential liver function under normal breeding conditions. However, the liver mass of knockout mice was 20% less than those of mice in the control groups. Expression analysis revealed loss of genes required for glutamine synthesis in knockout mice. Loss of the liver glutamine synthesis pathway did not affect the blood ammonia level in mice fed a standard diet, yet, knockout mice showed significantly elevated blood ammonia levels with high-protein dietary feeding. Furthermore, the expression of two cytochrome P450 enzymes, CYP1A2 and CYP2E1, was almost completely abolished in livers from hepatocyte-specific beta-catenin knockout mice. Consequently, these mice were resistant to acetaminophen challenge, confirming the requirement of these cytochrome P450 enzymes for metabolism of xenobiotic substances. In conclusion, in addition to regulating hepatocyte proliferation, beta-catenin may also control multiple aspects of normal liver function.

Acetaminophen↗
PubMed2006

Interobserver variability in histologic recognition, interpretation of KIT immunostaining, and determining MIB-1 labeling indices in gastrointestinal stromal tumors and other spindle cell tumors of the gastrointestinal tract.

The authors studied the concordance among seven pathologists for the histologic diagnosis, interpretation of KIT immunostaining, and determining MIB-1 labeling indices (LI) in 80 adult patients with primary spindle cell tumors, mainly of the gastrointestinal tract, mesentery, retroperitoneum, and pelvis, based on the review of tissue sections using an immunohistochemical panel of antibodies for KIT/CD117, CD34, desmin, smooth muscle actin (SMA), and S-100 protein. Tumors included 30 gastrointestinal stromal tumors (GISTs), 10 leiomyomas, 10 leiomyosarcomas, 10 schwannomas, 10 solitary fibrous tumors, and 10 desmoid-type fibromatoses. The overall concordance with the original diagnosis of each histologic type was 97.9%, the kappa value ranging from 0.95 to 1.00 (mean 0.97), indicating a perfect agreement. The overall interlaboratory concordance with the original interpretation of KIT immunostaining was 91.3%, the kappa value ranging from 0.77 to 0.90 (mean 0.86). The overall interlaboratory concordance with the original interpretation of KIT immunostaining was 91.9%, the kappa value ranging from 0.72 to 0.93 (mean 0.85). The overall concordance for determining MIB-1 LI was 90% with the original evaluation, and the overall kappa value ranged from 0.62 to 0.86 (mean 0.77). These results indicate that it is possible to reliably diagnose GIST and other spindle cell tumors of the gastrointestinal tract with the use of an immunohistochemical panel of antibodies for KIT, CD34, desmin, SMA, and S-100 protein. Although there is clearly unavoidable inter-observer and interlaboratory variability in the interpretation of KIT immunostained sections and interobserver variability in the determination of MIB-1 LI, the concordance between observes is very acceptable, and in most instances such variability can be eliminated by careful reviewing of the hematoxylin and eosin and immunostained sections.

Adult↗
PubMed2005

CD10 expression in colorectal carcinoma correlates with liver metastasis.

PURPOSE: If it were possible to identify the features of primary colorectal carcinoma that were associated with liver metastasis, these features could be used as predictors of liver metastasis. METHODS: From January 1995 to December 1997, 648 consecutive cases of colorectal carcinoma were recorded at the Department of Surgery, National Cancer Center Hospital, Tokyo, Japan. We evaluated clinicopathologic and immunohistochemical factors (age, gender, tumor location, gross type, size, histologic type, dedifferentiation of invasive front, depth of invasion, lymphatic invasion, venous invasion, lymph-node metastasis, and expression of CD10, MUC2, and human gastric mucin) in 505 of these patients who had undergone resection of T2/T3/T4 colorectal carcinomas to clarify the correlation between these factors and liver metastasis. RESULTS: Liver metastases, including unresectable, were detected in 122 patients (24 percent), all of whom had been followed for at least five years. Univariate analysis revealed that liver metastasis was significantly associated with tumor size, histologic type, dedifferentiation of invasive front, depth of invasion, lymphatic invasion, venous invasion, lymph-node metastasis, and CD10 expression. Multivariate analysis revealed that invasion deeper than the subserosa, venous invasion, lymph-node metastasis, and CD10 expression were significantly associated with liver metastases. CONCLUSIONS: CD10 expression in colorectal carcinoma is a good predictor of liver metastasis.

Adenocarcinoma↗
PubMed2004

Differential diagnosis of gastrointestinal stromal tumor and other spindle cell tumors in the gastrointestinal tract based on immunohistochemical analysis.

To confirm the usefulness of an immunohistochemical panel of antibodies for KIT (c-kit/CD117), CD34, desmin, smooth-muscle actin (SMA), h-caldesmon (HCD), S-100 protein, neuron-specific enolase (NSE), and beta-catenin, 297 mesenchymal and peripheral nerve-sheath tumors of the gastrointestinal tract and intra-abdominal locations including 211 gastrointestinal stromal tumors (GISTs), 12 leiomyomas, 18 leiomyosarcomas, 17 solitary fibrous tumors (SFTs), 14 schwannomas, and 25 desmoid-type fibromatoses (DTFs) were analyzed immunohistochemically. Consistent (100%) immunoreactivity for KIT, CD34, desmin and S-100, and nuclear accumulation of beta-catenin were detected in GISTs, SFTs, smooth-muscle tumors, schwannomas, and DTFs, respectively. Immunoreactivity for SMA, HCD, and NSE was observed in a wide range of these tumors. In addition, 418 bone and soft tissue tumors were enrolled in this study for KIT immunostaining. As a result, a limited number of these tumors were KIT positive, including synovial sarcoma that showed morphological similarity to GISTs. These findings suggest that KIT, CD34, desmin, S-100, and beta-catenin are key markers for clinical diagnosis of GISTs and other spindle cell tumors that may involve the gastrointestinal tract, whereas SMA, HCD, and NSE have only limited value.

Antigens, CD34↗
PubMed2004

Cytoplasmic p120ctn regulates the invasive phenotypes of E-cadherin-deficient breast cancer.

In a search for signaling molecules that act downstream of E-cadherin inactivation in cancer, we examined the expression and localization of E-cadherin-associated proteins in lobular carcinoma, in which the E-cadherin gene is frequently inactivated, and found that E-cadherin down-regulation correlated with the cytoplasmic localization of p120ctn. Similar cytoplasmic localization of p120ctn and growth factor-induced accumulation of tyrosine-phosphorylated p120ctn in the protrusive domain were observed in E-cadherin-deficient breast cancer cells. Down-regulation of endogenous p120ctn by RNA interference promoted stress fiber formation and induced a flattened morphology with an increase of Rho-GTPase activity; it also reduced the development of membranous protrusions and migratory activity in E-cadherin-deficient breast cancer cells. Inactivation of E-cadherin in cancer cells is associated with the conversion from epithelial to mesenchymal phenotype, which also occurs in physiological conditions such as developmental processes. Cytoplasmic localization of p120ctn accompanied by E-cadherin down-regulation was observed in mesoderm cells that had undergone epithelial-mesenchymal transition during early mouse embryogenesis. Collectively, our results suggest that cytoplasmic p120ctn may contribute to the invasive phenotype of E-cadherin-deficient breast cancer cells.

Base Sequence↗
PubMed2004

Diagnosis of intra-oral MALT lymphoma using seminested polymerase chain reaction.

Diagnosis of mucosa-associated lymphoid tissue (MALT) lymphoma based on histological examination alone is difficult. We report three patients with histologically suspected MALT lymphoma who developed lymphoproliferative lesions of the sublingual gland. Seminested polymerase chain reaction (PCR) analysis applied to formalin-fixed and paraffin-embedded specimens showed clonal rearrangement of immunoglobulin heavy chain genes in two patients and a polyclonal characteristic in one. The clinical findings and Southern blot analysis confirmed the accuracy of the diagnosis. The molecular method described can be applied routinely to processed specimens to obtain helpful information for the diagnosis of low-grade malignancies of lymphoproliferative disorders, such as MALT lymphoma.

Aged↗
PubMed2004

High-grade dysplasia associated with fundic gland polyposis in a familial adenomatous polyposis patient, with special reference to APC mutation profiles.

We report a patient with familial adenomatous polyposis who developed high-grade dysplasia against a background of fundic gland polyposis. Two large high-grade dysplasia lesions were found in the gastric body, where numerous fundic gland polyps were present. In both lesions, the dysplastic epithelium covered non-neoplastic oxyntic glands that occasionally exhibit cystic changes. A genetic analysis for APC (adenomatous polyposis coli) revealed a somatic 50-bp deletion involving codons 1502-1517 and 2-bp deletion at codon 1465 in each lesion of high-grade dysplasia. In contrast, six of the 18 fundic gland polyps were found to harbor an identical mutation: 1-bp insertion at codon 1556. Both lesions of high-grade dysplasia and the fundic gland polyps were similarly located in the fundic gland area and were caused by the inactivation of APC; however, their mutation profiles of APC were different. These results imply that fundic gland polyps and high-grade dysplasia of the stomach have distinct preferences for APC genotypes in their development.

Adenomatous Polyposis Coli↗
PubMed2003

Beta-catenin mutations in pulmonary blastomas: association with morule formation.

To elucidate the contribution of beta-catenin gene mutation to the development of pulmonary blastomas, we analysed mutations in three well-differentiated fetal adenocarcinomas (WDFAs) and six biphasic pulmonary blastomas (BPBs). For comparison, eight clear-cell adenocarcinomas with fetal lung features were also examined. beta-Catenin gene mutations were found in all three WDFAs, two BPBs, and none of the clear-cell adenocarcinomas with fetal lung features. All tumours with mutations had a common histological feature, namely morule formation, and showed a characteristic heterogeneous beta-catenin expression pattern that was revealed by immunohistochemistry. Strong nuclear/cytoplasmic expression of beta-catenin was seen in clustered cells in the morular areas and in single cells in glands, and was associated with neuroendocrine differentiation. As beta-catenin mutations are rare among lung tumours, this distinctive genetic feature, which is also immunohistochemically detectable as overexpression with a heterogeneous pattern, has diagnostic significance. The presence of this common genetic alteration found in both WDFA and BPB implies a histogenetic linkage between these tumours.

Adenocarcinoma↗
PubMed2003

Beta-catenin mutations are frequent in calcifying odontogenic cysts, but rare in ameloblastomas.

We have reported previously that alterations to beta-catenin occur frequently in adamantinomatous craniopharyngioma. Based on its histological resemblance to some odontogenic tumors, we suspected the presence of common genetic alterations among these tumors. To address this issue, 11 cases of calcifying odontogenic cyst (COC) and 20 cases of ameloblastoma were investigated for the presence of beta-catenin mutations and beta-catenin expression. Ten COCs were successfully analyzed by direct sequencing, and nine of them were found to harbor somatic beta-catenin mutations. Immunohistochemically, all of the COCs showed nuclear and cytoplasmic expression of beta-catenin with a heterogeneous pattern. No beta-catenin mutations were found in ameloblastomas, except for one case of the follicular type. All follicular ameloblastomas exhibited moderate nuclear and cytoplasmic accumulation of beta-catenin, in contrast to the predominantly membranous expression seen in the plexiform type. beta-Catenin mutation is considered to be a characteristic genetic feature of COC, and may play a critical role in its histogenesis. Although ameloblastoma closely resembles COC histologically, the two have genetically distinctive features.

Adolescent↗
PubMed2002

Target disruption of the mutant beta-catenin gene in colon cancer cell line HCT116: preservation of its malignant phenotype.

Most colorectal carcinomas harbor genetic alterations that result in stabilization of beta-catenin. A colorectal carcinoma cell line, HCT116, which has both mutated and wild-type beta-catenin genes, was engineered by homologous recombination to investigate the significance of beta-catenin gene mutation. As expected, the mutant allele-targeted clones showed decreased beta-catenin expression and downregulation of T-cell factor (TCF)/lymphoid enhancer factor (LEF)-dependent transcription. Morphologically, targeted clones were only minimally altered under usual culture conditions, but under low serum conditions, mutant allele-targeted clones still grew in plane, in contrast to parental cell line and wild allele-targeted clones, which formed spheroids. The mutant allele-targeted clones showed no significant changes in growth rate and anchorage-independent growth in vitro, and displayed rather increased growth in vivo. Although beta-catenin stabilization affects some biological characteristics including adhesive properties, it may not have growth-promoting effects at least in some colorectal carcinomas.

Animals↗
PubMed2002

Craniopharyngiomas of adamantinomatous type harbor beta-catenin gene mutations.

Craniopharyngioma is a rare tumor occurring in the sellar region comprising 3% of all intracranial tumors. To elucidate the contribution of beta-catenin gene mutation to tumorigenesis, we examined genetic alterations and expression of beta-catenin in 10 cases of adamantinomatous and 6 cases of papillary craniopharyngiomas. Beta-catenin gene mutations were found in all of the adamantinomatous and none of the papillary craniopharyngiomas. Immunohistochemically, all cases of adamantinomatous craniopharyngioma showed cytoplasmic and nuclear expression of beta-catenin. In contrast, papillary craniopharyngiomas showed exclusively membranous expression. The results suggest that adamantinomatous- and papillary-type craniopharyngiomas are not only clinicopathologically, but also genetically, distinctive variants. Mutation of the beta-catenin gene therefore seems to play an important role in the tumorigenesis of adamantinomatous craniopharyngioma. Among the adamantinomatous-type tumors, beta-catenin-positive mesenchymal cells were observed in two cases. Microdissection-based mutational analysis revealed that these mesenchymal cells also harbor the same beta-catenin gene mutations as those of epithelial cells, suggesting their tumorous nature. Thus, at least a subset of adamantinomatous craniopharyngioma is considered to be biphasic.

Adult↗
PubMed2001

Beta-catenin mutations in sporadic fundic gland polyps.

Fundic gland polyp (FGP) is the most common gastric polyp. It occurs sporadically or in association with familial adenomatous polyposis (FAP). FAP patients carry germline mutations of the adenomatous polyposis coli (APC) gene, and previous studies have revealed frequent somatic mutations of the APC gene in FGPs associated with FAP. Although inactivation of the APC gene contributes to histogenesis of FGPs associated with FAP, this rarely happens in sporadic cases. Loss of the APC gene promotes abnormal accumulation of beta-catenin, and mutation of GSK-3 beta phosphorylation sites in the beta-catenin gene can have a similar effect. To elucidate the contribution of beta-catenin gene mutation to the histogenesis of sporadic FGP, we analyzed beta-catenin gene mutation in exon 3 in 45 FGP lesions obtained from 35 patients. Somatic mutations were found in 29 lesions: 28 were missense mutations and one was an in-frame deletion. All of the missense mutations were confined to the former two serine residues of the GSK-3 beta phosphorylation sites and their flanking residues (codons 32, 33, 34, 37). Analysis in cases with multiple FGPs revealed a different mutation in each lesion, indicating their multicentric origin. Therefore, a significant proportion of sporadic FGPs have genetic alterations involving beta-catenin stabilization, as did FAP-associated FGPs.

Adult↗