Biomedical subjects

Sadafumi Tamiya

Publications and source records attributed to Sadafumi Tamiya.

At least 37 records · Page 2Linked to original sources

PubMed2004

Death-associated protein kinase (DAP kinase) alteration in soft tissue leiomyosarcoma: Promoter methylation or homozygous deletion is associated with a loss of DAP kinase expression.

The death-associated protein kinase (DAP kinase) was initially identified as a positive mediator of programmed cell death induced by interferon-gamma. To investigate the potential role and the alteration of the DAP kinase gene in soft tissue leiomyosarcoma (LMS), we first searched for homozygous deletion and promoter hypermethylation in 45 LMSs for which genomic DNA was available, using differential PCR and methylation-specific PCR, respectively. Promoter methylation was recognized in 10 of 45 cases (22%), and homozygous deletion was detected in 3 of 45 cases (7%). p53 mutation was detected in 11 of 45 LMS cases (24%). Cases with DAP kinase alteration or p53 mutation showed a close correlation with high French Federation of Cancer Centers grade or with poor prognosis (P = 0.0244, P = 0.0491, respectively). Next, to determine that DAP kinase promoter methylation or homozygous deletion is involved in the down-regulation of DAP kinase expression, we examined the expression of DAP kinase protein by immunohistochemistry. Decreased expression of DAP kinase protein was recognized in 13 of 45 LMS cases (29%). Seven of 13 cases (54%) with decreased expression of DAP kinase protein revealed promoter methylation or homozygous deletion of DAP kinase, and the methylation status or homozygous deletion of its gene showed a close correlation with decreased DAP kinase expression (P = 0.0300). In conclusion, although DAP kinase alteration was relatively rare, DAP kinase alteration and/or p53 mutation may associate with tumor progression in soft-tissue LMSs. Furthermore, although further detailed analyses are necessary, promoter methylation or homozygous deletion status of DAP kinase may present a major alternative mechanism of a loss of or decrease in DAP kinase expression.

Adult↗

PubMed2004

Frequent microsatellite instability in synchronous ovarian and endometrial adenocarcinoma and its usefulness for differential diagnosis.

Synchronous tumors of the ovary and endometrium are a well-known phenomenon. There are histological criteria for defining double primary tumors or metastasis from one organ to another, but in some cases a precise diagnosis is difficult. In this study we reviewed 17 cases of synchronous ovarian and endometrial adenocarcinoma by previously reported histological criteria and performed a microsatellite analysis, combined with X-linked clonality analysis. We also analyzed 8 cases of endometrial adenocarcinoma with pelvic lymph node metastasis as a control. Five dinucleotide microsatellite markers were selected, and microsatellite analysis was performed by a high-resolution method using fluorescence-labeled polymerase chain reaction and laser scanning. In synchronous tumors, 11 ovarian carcinomas (65%) and 10 endometrial carcinomas (59%)demonstrated microsatellite instability (MSI). In total, 13 of the 17 patients demonstrated MSI in the ovarian tumor, the endometrial tumor, or both. Four cases of endometrial carcinoma with pelvic lymph nodes metastases displayed MSI, and MSI findings of the endometrial tumor and lymph node metastasis were same in all cases. Based on these findings, we considered that similar MSI findings indicate metastatic tumors. According to the MSI findings, 13 of the 17 patients (76%) had single or double clonal tumors, 11 (67%) with double primary tumors and 2 (13%) with metastatic tumors. Using X-linked clonality analysis, 3 patients were diagnosed with double primary tumors. The molecular diagnosis corresponded with the histological criteria in all but 1 case. In conclusion, using both MSI and X-linked clonality analysis, most patients (82%) could be diagnosed as having single or double clonal tumors. The histological criteria are accurate and useful in most cases; however, in some cases where the relationship between the 2 tumors is difficult to determine, high-resolution MSI analysis may be helpful.

Adenocarcinoma↗

PubMed2004

Altered expression and molecular abnormalities of cell-cycle-regulatory proteins in rhabdomyosarcoma.

Rhabdomyosarcoma is the most commonly occurring soft-tissue sarcoma in children. Some reports have discussed the altered expression and molecular abnormalities of cell-cycle-regulatory proteins in rhabdomyosarcoma; however, variable frequencies of occurrence have been noted. In the current study, among 72 cases of rhabdomyosarcoma, the authors evaluated for the expression of p53, MDM2, p16, p21/WAF1, p27, cyclin D1, cyclin E, pRb and E2F-1 protein immunohistochemically and assessed for proliferative activities using MIB-1. We also analyzed the mutation of the p53 gene in 45 cases, the amplification of the MDM2 gene in 18 cases and the mutation of the H-ras gene in 29 cases, using formalin-fixed paraffin-embedded materials. Furthermore, we assessed the correlation between clinicopathologic factors and the results of both immunohistochemical and molecular analyses. Alveolar type affected older patients, and it had a significantly higher mitotic rate compared with the embryonal type (P=0.0226). p53 overexpression was detected in 22 (30.6%) of 72 cases, and 10 (22.2%) of 45 cases had p53 gene abnormalities. As for MDM2, its overexpression was found in nine (12.5%) of 72 cases, and three (16.7%) of 18 cases showed MDM2 amplification. A statistically significant association was observed between immunoreaction for MDM2 and p53 overexpression (P=0.0002), and p53 and MDM2 overexpression was significantly correlated with high MIB-1 labeling indices. E2F-1 labeling indices showed a significantly higher score in alveolar type compared with that seen in embryonal type (P=0.0334), but MIB-1 did not. In conclusion, our study suggests that p53 overexpression may be related to tumor progression because tumors with p53 overexpression have a high proliferative activity in the current study. Alveolar type had a significantly higher both mitotic rate and E2F-1 labeling indices when compared with the embryonal type. The current study is the first report of the correlation of E2F-1 with alveolar rhabdomyosarcoma.

Adolescent↗

PubMed2004

c-kit and PDGFRA mutations in extragastrointestinal stromal tumor (gastrointestinal stromal tumor of the soft tissue).

Extragastrointestinal stromal tumor (EGIST) is a unique tumor that occurs outside the gastrointestinal tract. EGIST shows a c-kit expression and histologic appearance similar to those of gastrointestinal stromal tumor (GIST). Most GISTs have gain-of-functional mutation of the c-kit gene, and some have mutation of the platelet-derived growth factor receptor-alpha (PDGFRA) gene. However, the frequency of mutation of those genes in EGISTs remains unclear. We examined the clinicopathologic features, prognostic factors, and c-kit and PDGFRA mutation in 39 cases of EGIST. Tumors with high mitotic counts (>or=5/50 high power fields) or a high Ki-67 labeling index (>or=10%) were significantly correlated with worse prognoses. The c-kit mutation was found in the juxtamembrane domain (exon 11) and the extracellular domain (exon 9) in 12 of 29 cases (41.4%) and 2 of 29 cases (6.9%), respectively. The PDGFRA gene mutation was found at the juxtamembrane domain (exon 12) and the tyrosine kinase domain (exon 18) in one case each. The pattern of kit and PDGFRA mutation in EGIST was essentially similar to that in GIST. Our results suggest that the c-kit and PDGFRA mutations play an important role in the tumorigenesis of EGIST. High mitotic counts and a high Ki-67 labeling index may be useful for predicting the aggressive biologic behavior in EGIST. Furthermore, STI-571, targeting c-kit and PDGFR tyrosine kinase, seems to be a possible therapeutic strategy for EGISTs, especially advanced cases.

Adult↗

PubMed2004

Alterations of the p16INK4a/p14ARF pathway in clear cell sarcoma.

Clear cell sarcoma (CCS) is a very rare soft tissue sarcoma with a poor prognosis. It has become apparent through immunohistochemical, ultrastructural, and microarray analyses that CCS is a soft tissue melanocytic neoplasm. Alterations in the p16INK4a/p14ARF gene are common in malignant melanoma, which is the prototypical melanocytic neoplasm. In the present study, we performed a clinicopathologic analysis and investigated p16 and cyclin D1 expression by immunohistochemistry in 14 cases. Furthermore, we investigated genetic changes of various tumor suppressor genes and an oncogene, including p16INK4a/p14ARF, p53, beta-catenin, and APC, in 11 cases. The 5-year overall survival rate in all the patients was 33.3%. A high mitotic rate was a significant adverse prognostic factor (P = 0.004). Decreased expression of p16 was observed in 4 (28.6%) of 14 cases. Overexpression of cyclin D1 was observed in 9 cases (64.3%). SSCP analysis followed by DNA direct sequencing revealed point mutations of the p16INK4a gene in 2 of 11 cases (18.2%). In addition, one case with the p14ARF mutation and 2 cases with the p53 mutation were observed. None of the cases harbored mutation of the beta-catenin or APC gene. Homozygous deletion of the p16INK4a/p14ARF gene was detected in one case. Methylation-specific PCR did not reveal hypermethylation of the p16INK4a/p14ARF promoter region in any of the cases. Three cases harbored genetic alterations of the p16INK4a/p14ARF gene (27.3%). All tumors with genetic alterations of the p16INK4a/p14ARF or p53 gene showed a high mitotic rate or tumor necrosis. These alterations were considered to be influential in the poor prognosis of CCS patients.

Adult↗

PubMed2003

PTEN/MMAC1 gene mutation is a rare event in soft tissue sarcomas without specific balanced translocations.

The tumor suppressor gene PTEN/MMAC1 was identified on chromosome 10q23.3, which is homozygously deleted in many human malignancies. The loss of chromosome 10q was also frequently reported in some types of soft tissue sarcomas. Our study was designed to investigate the frequency of PTEN/MMAC1 gene mutation and to evaluate the role of the PTEN/MMAC1 gene in the tumorigenesis of soft tissue sarcomas without specific balanced translocations. We analyzed 51 cases of soft tissue sarcomas without specific balanced translocations for PTEN/MMAC1 mutations by polymerase chain reaction-single strand conformation polymorphism and direct sequencing. Mutations in the PTEN/MMAC1 gene were found in only 2 cases (3.9%). Both tumors with PTEN/MMAC1 mutation were leiomyosarcomas arising from the retroperitoneum and inferior vena cava, respectively. Two of 3 leiomyosarcomas arising from the intra-abdominal cavity examined harbored mutations of this tumor suppressor gene. This result suggests that leiomyosarcomas derived from the intra-abdominal cavity might have different tumorigenesis from those of an extremity or the trunk, from the viewpoint of PTEN/MMAC1 mutation, although PTEN/MMAC1 gene mutations are rare event in these soft tissue sarcomas.

Base Sequence↗

PubMed2003

Mechanisms of inactivation of the p16INK4a gene in leiomyosarcoma of soft tissue: decreased p16 expression correlates with promoter methylation and poor prognosis.

The p16INK4a tumour suppressor gene, encoding p16 protein, plays a crucial role in regulation of the G1 cell-cycle phase. To investigate the potential role of p16 in soft tissue leiomyosarcoma (LMS), an immunohistochemical analysis was performed of 77 LMSs for p16 expression. Decreased expression of the p16 protein was identified in 25 of 77 LMSs (32%). Decreased expression of p16 correlated significantly with large tumour size (p=0.0038). In a univariate analysis, large tumour size and decreased expression of p16 were statistically significant adverse prognostic factors (p=0.025 and p=0.0021, respectively). In a multivariate analysis including conventional clinicopathological parameters, decreased expression of p16 protein was revealed as the only independent unfavourable prognostic factor (p=0.012). To elucidate the mechanisms of inactivation of the p16INK4a gene, 49 LMSs for which genomic DNA was available were examined; analysis for homozygous deletion, mutation, and promoter hypermethylation was conducted using differential PCR, PCR-SSCP, and methylation-specific PCR, respectively. Promoter hypermethylation was detected in 11 of 49 LMS cases (22%); homozygous deletion was detected in 3 of 49 cases (6%); and mutation was not recognized in any of the cases studied. Eight of 15 cases (53%) with decreased expression of p16 protein revealed methylation of the p16INK4a gene promoter. Promoter hypermethylation correlated closely with decreased expression and poor prognosis (p=0.0014 and p=0.0088, respectively). These results suggest that decreased expression of p16 protein can be considered as an independent reliable prognostic parameter in patients with soft tissue LMS. Furthermore, promoter methylation was more frequent than either homozygous deletion or mutation in this tumour, and promoter methylation was also shown to have a strong association with inactivation of the p16INK4a gene.

Adolescent↗

PubMed2003

Limitin, an interferon-like cytokine, transduces inhibitory signals on B-cell growth through activation of Tyk2, but not Stat1, followed by induction and nuclear translocation of Daxx.

OBJECTIVE: Limitin, an interferon-like cytokine, suppresses B lymphopoiesis through ligation of the interferon-alpha/beta (IFN-alpha/beta) receptor. The aim of this study was to examine the intracellular signal transduction pathways activated by limitin. MATERIALS AND METHODS: The effects of limitin on cell growth, the activation of Jak kinase and Stat proteins, and the induction of interferon regulatory factor-1 (IRF-1) and Daxx were examined using the mouse pre-B-cell line 18.81, wild-type, and Tyk2-deficient mouse bone marrow cells. In addition, the change of localization of the Daxx protein after limitin treatment in wild-type and Tyk2-deficient mice was examined. RESULTS: Limitin phosphorylates Tyk2, Jak1, Stat1, and Stat2 and rapidly induces IRF-1 mRNA production. Phosphorylation of Stat1 by limitin is partially dependent on Tyk2. Suppression of B-cell growth by limitin, however, is severely impaired in the absence of Tyk2, whereas it is unaffected by the absence of Stat1. Limitin also induces the expression and nuclear translocation of Daxx, which is essential for IFN-alpha-induced inhibition of B-lymphocyte development. The absence of Tyk2 abrogates this induction of Daxx expression and nuclear translocation. CONCLUSIONS: Limitin suppresses B-cell growth through activation of Tyk2, resulting in the up-regulation and nuclear translocation of Daxx. This limitin-mediated signaling pathway does not require Stat1.

Active Transport, Cell Nucleus↗

PubMed2003

Possible association between tumor-suppressor gene mutations and hMSH2/hMLH1 inactivation in alveolar soft part sarcoma.

Alveolar soft part sarcoma (ASPS) is a rare soft tissue tumor of unknown origin and pathogenesis. We clinicopathologically analyzed 16 cases of ASPS and screened for the genetic alterations of various tumor-suppressor genes and oncogenes, including p53, adenomatous polyposis coli (APC), E-cadherin, and beta-catenin, in 11 cases of ASPS. We also examined the expression of hMSH2/hMLH1 of DNA mismatch repair genes by immunohistochemistry, and promoter hypermethylation of these DNA mismatch repair genes by methylation-specific polymerase chain reaction (MS-PCR) to elucidate any possible association between mutation status of these genes and inactivation of the hMSH2/hMLH1 genes. Furthermore, microsatellite instability (MSI) analysis and loss of heterozygosity (LOH) on chromosome 5q analysis were used for some cases of ASPS where DNA derived from normal tissue was available. The 5-year overall survival rate for all of the patients in this study was 68.6%. The 5-year overall survival rates for patients presenting with localized ASPS and for patients with distant metastases were 83.3% and 47.6%, respectively. The high nuclear grade of tumor cells was a significantly adverse prognostic factor (P = 0.0085). Single-strand conformation polymorphism analysis followed by DNA direct sequencing revealed 4 point mutations of the p53 gene in 3 of 11 cases (27.3%), composed of 3 missense mutations and 1 silent mutation. In addition, 1 case with the E-cadherin missense mutation and 1 case with the APC missense mutations were observed, respectively. None of the cases harbored mutation of exon 3 of the beta-catenin gene. Loss of expression of the hMSH2 and hMLH1 genes was observed in 2 (18.2%) and 3 (27.3%) of 11 cases, respectively. All 3 cases with loss of hMLH1 gene expression harbored mutations of the p53 gene. There was a statistically significant correlation between the genetic alteration positive in these tumor-suppressor genes and loss of hMLH1 gene expression (P = 0.024). Methylation-specific PCR did not reveal hypermethylation of the hMSH2/hMLH1 promoter region in any of the cases examined. Three of 8 (37.5%) ASPS cases showed low MSI, and 2 of these 3 cases showed immunohistochemical lack of expression for either hMSH2 or hMLH1. LOH on 5q was present in 2 of 6 (33.3%) informative cases, and both cases showed LOH on the D5S346 marker, a microsatellite marker near the APC locus. Thus, inactivation of hMSH2/hMLH1 of DNA mismatch repair genes seems to have an important role to play in the mutagenesis of the tumor-suppressor genes in ASPS.

Adaptor Proteins, Signal Transducing↗

PubMed2003

Mixed tumor of deep soft tissue.

Mixed tumors of the salivary gland and skin are relatively common but are quite rare in soft tissue. It is believed that, as in the salivary gland form, most of these lesions are benign, but that a small subset behave in an aggressive fashion. We report here a patient with recurrent mixed tumor of soft tissue with infiltrative growth. The primary tumor arose in deep subfascial soft tissue of the right lower leg and was adjacent to the surface of the fibula. An open biopsy and complete resection were performed. Upon histological examination of the resected specimen, neoplastic cell infiltration at the tumor/soft tissue interface was not obvious; local recurrence, however, was observed 1 year later. The patient was treated with wide resection. Histological examination confirmed that the recurrent tumor with an extensive chondroid area invaded the osseous tissue of the fibula. At present, 1 year after the second resection surgery, there is no evidence of disease.

Adenoma, Pleomorphic↗

PubMed2003

Cytogenetic and clinicopathological analysis of soft-tissue leiomyosarcomas.

To identify a characteristic cytogenetic aberration and cytogenetic-morphological correlation in soft-tissue leiomyosarcomas, a karyotypic and clinicopathological analysis of 15 cases of leiomyosarcoma was performed. The histological type was classical in nine cases, pleomorphic in three cases and myxoid in three cases. The histological grade was 1 in three cases, 2 in 10 cases and 3 in two cases. Nine of 15 tumors displayed an abnormal karyotype, whereas the other six tumors displayed a normal karyotype. The relative consistency of involvement of 3p, 3q, 6q, 7p, 7q, 9p, 10p, 11p, 11q, 12p, 16q, 17p and 19q was recognized, although characteristic chromosomal rearrangements were not detected. All six tumors that had a normal karyotype were of the classical type, whereas those displaying an abnormal karyotype contained another morphological type along with the classical type. The results of the present study suggest that chromosomal aberrations contribute to morphological changes in soft-tissue leiomyosarcomas.

Adult↗

PubMed2003

Altered expression of cell cycle regulators in myxofibrosarcoma, with special emphasis on their prognostic implications.

Myxofibrosarcoma/myxoid malignant fibrous histiocytoma (MFH) has continued to be considered a distinct entity even after recently published reassessments of pleomorphic sarcomas and MFH. Several cell cycle-regulated proteins have already been screened by immunohistochemistry with the aim of finding the reliable prognostic indicator of soft tissue sarcomas; however, it is still unknown whether their altered expression affects patient survival in myxofibrosarcoma. In this study, we evaluated the expression of p53, MDM2, MIB-1 (Ki-67), p21, p27, p16, cyclin A, cyclin D1, and cyclin E by immunohistochemistry in 45 cases of myxofibrosarcoma. First, we searched for possible clinicopathologic prognostic factors in 61 cases of myxofibrosarcoma for which follow-up data were available. In univariate analysis, large tumor size (> or =5 cm), deeply situated tumor, and high histological grade (grade 2 or 3) significantly decreased survival (log-rank test, P <0.05). Among 43 cases of myxofibrosarcoma for which immunohistochemical findings were available, high MIB-1 labeling index (LI) (cutoffs of 10 and 22.5 on average), high cyclin A LI (cutoffs 10% and 13.8% on average), low p21 LI (cutoffs 10 and 20.7 on average), and reduced abnormal expression of p16 were adverse prognostic factors. In multivariate analysis (Cox proportional hazards model), high mitotic rate (>15/10 high-power fields), p53 immunoreactivity (cutoff 10%), high MIB-1 LI (>22.5), low p21 LI (<20.7), and low p27 LI (<47.8 on average) were independent poor prognostic factors. Our results suggest that reduced expression of p21 could be considered a new parameter to be evaluated, along with classical clinicopathologic prognostic factors, for identifying those at high risk for myxofibrosarcoma.

Adult↗

PubMed2002

Cutting edge: tyk2 is required for the induction and nuclear translocation of Daxx which regulates IFN-alpha-induced suppression of B lymphocyte formation.

IFN-alpha inhibits B lymphocyte development, and the nuclear protein Daxx has been reported to be essential for this biological activity. We show in this study that IFN-alpha inhibits the clonal proliferation of B lymphocyte progenitors in response to IL-7 in wild-type, but not in tyk2-deficient, mice. In addition, the IFN-alpha-induced up-regulation and nuclear translocation of Daxx are completely abrogated in the absence of tyk2. Therefore, tyk2 is directly involved in IFN-alpha signaling for the induction and translocation of Daxx, which may result in B lymphocyte growth arrest and/or apoptosis.

Active Transport, Cell Nucleus↗

PubMed2002

Expression of AIRE gene in peripheral monocyte/dendritic cell lineage.

The responsible gene for autoimmune polyglandular syndrome type 1, known as autoimmune regulator (AIRE), was identified by positional cloning. The AIRE gene was reported to be expressed in the thymus medulla and lymph nodes. However, an expression of the AIRE gene in peripheral blood cells has not yet been reported. In the present study, we found that the AIRE gene was restrictively expressed in peripheral CD14-positive monocytes but not in CD4-positive T cells nor polymorphonuclear cells, as assessed by RT-PCR. Moreover, immunocytochemical study revealed the expression of the AIRE protein not only in CD14-positive monocytes but also in differentiated dendritic cells, cultured in RPMI1640 medium containing 800 U/ml GM-CSF, 1000 U/ml IL-4 and 100 U/ml TNF-alpha. Thus, it was concluded that the AIRE gene is restrictively expressed in the peripheral monocyte/dendritic cell lineage.

Cell Lineage↗

PubMed2002

APC mutations in synovial sarcoma.

It has previously been demonstrated that accumulated beta-catenin serves as an oncoprotein in synovial sarcoma and results in a poor overall survival rate, but the frequency of beta-catenin mutation was quite low (8.2%). The present study, using essentially the same study group of cases, screened for genetic alterations in the mutation cluster region (MCR) of the APC gene in 49 cases of synovial sarcoma. SSCP analysis followed by DNA direct sequencing revealed five missense APC mutations in four cases of synovial sarcoma (8.2%). The mutational sites comprised one case each at codons 1299 (GCT to ACT, Ala to Thr), 1412 (GGA to AGA, Gly to Arg), and 1414 (GTA to ATA, Val to Ile), in addition to one case with double point mutations at codon 1398 (AGT to AAT, Ser to Asn) and at codon 1413 (ATG to ATA, Met to Ile), together with beta-catenin mutation at codon 32 (GAC to TAC, Asp to Tyr). All four cases with APC mutations were histologically of the monophasic fibrous type and showed beta-catenin accumulation. All three cases with APC mutations available for follow-up data were long survivors. This study provides the first evidence that APC mutations also occur in the field of sarcoma, especially in synovial sarcoma.

Adult↗

PubMed2002

Ileal perforation in diffuse intestinal Behçet disease: report of a case.

Intestinal ulcers in Behçet disease tend to cause perforation, and postoperative recurrence is common with a high mortality rate. The optimal therapeutic strategy has yet to be elucidated, particularly in cases of diffuse intestinal involvement. We herein present a case of diffuse intestinal Behçet disease with ileal perforation. A 57-year-old Japanese woman was referred to our institution with complaints of intractable oral ulcers and abdominal pain. The patient underwent an emergency laparotomy for perforated peritonitis in spite of the intravenous administration of prednisolone (1.5 mg/kg) under total parenteral nutrition. Macroscopically, an inflamed ileum measuring 1.6 m in length was resected, including a 1-cm perforated ulceration. Innumerable small and deep ulcers were also observed, consisting of nonspecific inflammation. The patient has been free from any recurrence of intestinal ulcers while being treated with prednisolone, colchicine, and a low-residue diet for 1.5 years.

Behcet Syndrome↗

PubMed2002

Possible association between higher beta-catenin mRNA expression and mutated beta-catenin in sporadic desmoid tumors: real-time semiquantitative assay by TaqMan polymerase chain reaction.

We screened for genetic alterations of adenomatous polyposis coli (APC) and beta-catenin genes in 17 frozen specimens from 12 cases of sporadic desmoid tumors and then subdivided these cases into two groups according to the results of mutational analysis. We further examined mRNA expression of beta-catenin and cyclin D1 by TaqMan PCR and compared the mRNA expression within both groups. Single-strand conformation polymorphism analysis followed by DNA direct sequencing revealed beta-catenin mutation in 3 of 12 cases (6 of 17 specimens), whereas no APC missense mutations in the mutation cluster region were found. TaqMan PCR revealed extremely higher mRNA expression of beta-catenin and cyclin D1 in desmoid tumors, compared with those of normal skeletal muscles. In the beta-catenin mutated group, cyclin D1 mRNA expression was significantly higher than that of the beta-catenin wild-type group (p = 0.0120, Mann-Whitney U test). In addition, in the beta-catenin mutated group, beta-catenin mRNA expression was also significantly higher than that of the beta-catenin wild-type group (p = 0.0036, Mann-Whitney U test). All cases of desmoid tumors showed detectable beta-catenin nuclear expression immunohistochemically. These results suggest that a continuously elevated beta-catenin protein level caused by the beta-catenin mutation itself may have a stronger power that can transactivate transcription in vivo. Furthermore, the results provide a possible association between higher beta-catenin mRNA expression and mutated beta-catenin in sporadic desmoid tumors. This may suggest that the beta-catenin gene may be up-regulated by mutated or continuously elevated beta-catenin protein, that is, the beta-catenin gene may also be one of the targeted genes in the APC-beta-catenin-Tcf pathway.

Adolescent↗

PubMed2002

Mutation analysis of human cytokeratin 8 gene in malignant rhabdoid tumor: a possible association with intracytoplasmic inclusion body formation.

The rhabdoid cell, which is typically observed in malignant rhabdoid tumor (MRT) and other malignant neoplasms, has an eosinophilic cytoplasm containing a spheroid perinuclear inclusion body. This distinct cell is known to act as a highly aggressive indicator in many types of malignant tumors and is characterized by aggregates of intermediate filaments, comprising both vimentin and cytokeratin (CK) 8, which is mainly expressed in simple-type epithelium such as liver and intestine. To clarify the cause of the inclusion body formation, we analyzed the alteration of the complete human CK8 gene (KRT 8: 1724 base pairs) in seven samples of MRT (three from frozen materials and four from cultured cell lines) by reverse-transcriptase polymerase chain reaction, followed by direct sequencing. In addition, the two cell lines, Huh7 and HeLa, which lacked rhabdoid feature, six pediatric malignant tumors, including three cases of primitive neuroectodermal tumor (PNET) and three of Wilms' tumor; and 15 normal liver tissue (as a control) were also analyzed. All MRT samples had missense mutations in the human KRT 8 gene, i.e., Arg89 --> Cys (5/7); Arg --> Cys251 (3/7); Glu267 --> Lys (6/7); Ser290 --> Ile, Met; (7/7) and Arg301 --> His(4/7), none of which was detected in any control samples. Among these mutations, the most noteworthy findings were that Arg89 belongs to the H1 subdomain of the head domain and that Arg251 belongs to the short nonhelical linker segment, or L1-2. Both these mutations are noted for their relationships to lateral protofilament-protofilament interactions. In addition, Ser290 has been previously reported to be a phosphorylation site, which has been recognized to play an important role in filament organization, leading to conformational change of the CK8 filaments. In conclusion, mutated codons of CK8 gene in MRT were located in the important region involved in the conformational change of intermediate filament.

Amino Acid Sequence↗