Hajime Horiuchi

Role of ras mutation in the progression of thyroid carcinoma of follicular epithelial origin.

The histological differentiation of thyroid carcinoma is known to correlate with prognosis. Ras oncogene mutations, which have been identified in various human cancers, have been suspected playing an important role in carcinogenesis and tumor progression. The purpose of this study was to clarify the mechanism of thyroid tumor progression, focusing on ras oncogenes. We examined ras mutations using nested polymerase chain reaction (PCR) and direct sequencing methods. The ras oncogene product was also examined immunohistochemically. Our results indicated that the incidence of ras mutations correlated with the histological differentiation of thyroid cancer. Three poorly differentiated carcinomas showed a higher rate of ras mutations than did 17 well-differentiated counterparts. Hot spots were not identified except for a relative accumulation of the N-ras gene at codon 61. There was a correlation between the immunoreactivity of the ras oncogene product and ras mutation, although the immunoreactivity of ras-p21 did not correlate with the histological differentiation. Mutation of the ras gene seemed to be one of the important events in the progression from well-differentiated carcinoma to poorly differentiated thyroid carcinoma.

Anomalous Cadherin Expression in Osteosarcoma: Possible Relationships to Metastasis and Morphogenesis

Two isoforms of the human cadherin-11/OB-cadherin gene, the intact and the variant forms, had been isolated from an osteosarcoma cDNA library. The intact form has a typical cadherin structure, whereas the variant form, generated by alternative splicing, encodes a cytoplasmic domain that is completely different from that of the intact form and lacks a homophilic cell-cell adhesion ability. At the protein level, the secreted form generated from the intact cadherin-11 is present. We examined the expression of the intact and the variant forms of cadherin-11 in 23 primary and metastatic osteosarcomas from 22 patients by reverse transcriptase-polymerase chain reaction (RT-PCR) analyses, revealing that all 23 tumors in the patients expressed the variant form and three of them expressed it prominently. On the other hand, Western blot analyses of six tumors showed that the secreted form was strongly expressed, and furthermore, expression of N-cadherin was extremely low. Overexpression of the intact cadherin-11 cDNA in osteosarcoma cell lines demonstrated that the secreted form is derived from the intact form of cadherin-11 in osteosarcoma. Immunohistochemically, cadherin-11, N-cadherin, and beta-catenin were expressed at the cell surface of fetal osteoblasts, whereas in osteosarcoma cells, they were expressed only focally or weakly in the cytoplasm. Considering the function of cadherin in carcinomas, it is suggested that the anomalous expression of human cadherin-11 in osteosarcoma and the reduced expression of N-cadherin play a role in metastasis and the irregular morphology in the highly malignant mesenchymal tumor.

Multiple small intestinal stromal tumors with skeinoid fibers in association with neurofibromatosis 1 (von Recklinghausen's disease)

A case of multiple small Intestinal stromal tumors (SIST) with skeinoid fibers of the jejunum arising in a 50 year old male with neurofibromatosis 1 (NF‐1) is reported. Seven small tumors of the jejunal wall were incidentally found and excised during an operation for abdominal and retroperitoneal neuroflbromas. Histologlcally, the tumors were composed of uniform spindle‐shaped cells with fascicular pattern, almost indistinguishable from the histology in leiomyoma. Periodic acid Schiff stain‐positive hyaline globules were observed among the tumor cells. Ultrastructurally, these globules were stromal tangles of curvilinear, fluffy fibrils, consistent with skeinoid fibers. The electron‐dense granules, possibly neurosecretory granules, were found In the cytoplasm of the tumor cells. Immunohistochemically, the tumor cells were positive for vimentin, neuron specific enolase and CD34, but negative for muscle markers and S100 protein. The association of NF‐1 and multiple SIST with skeinoid fibers may have clinical implications. The multiple occurrence of SIST with skeinoid fibers seems to be often cited as one of the gastrointestinal manifestations of NF‐1. The possible site of origin of SIST with skeinoid fibers in NF‐1 may be the enteric autonomlc nerve plexus in the small intestinal wall.

Histopathologic Study of Human Lacrimal Gland

PURPOSE Histopathologic changes in human lacrimal gland were investigated, and the relation between histopathologic parameters and patient age and sex, as well as the histopathologic differences between palpebral and orbital lobes of the lacrimal gland were analyzed. METHODS Samples of the main human lacrimal gland that included the palpebral lobes and orbital lobes were taken in 80 autopsies. A statistical analysis was made based on light microscope observations with the following histopathologic changes as parameters: (1) fibrosis (focal, lobular, and diffuse); (2) acinar atrophy (focal, lobular, and diffuse); (3) periductal fibrosis; (4) interlobular ductal dilatation; (5) interlobular ductal proliferation; (6) lymphocytic foci; (7) periductal lymphocytic infiltration; and (8) fatty infiltration. RESULTS The incidences of these parameters in the palpebral and orbital lobes ranged from 3.8% to 35.0%. Lobular fibrosis, lobular atrophy, diffuse fibrosis, diffuse atrophy, periductal fibrosis, lymphocytic infiltration, and fatty infiltration were more frequent in the orbital lobes with statistical significance, whereas interlobular ductal dilatation was more frequent in the palpebral lobes. There were statistically significant correlations between age and diffuse fibrosis, diffuse atrophy, and periductal fibrosis in the orbital lobes of women, and periductal fibrosis in the palpebral lobes of men. Diffuse fibrosis and diffuse atrophy in the orbital lobes were observed more frequently in elderly women than in elderly men. CONCLUSIONS Various histopathologic changes were observed in the human lacrimal gland. Diffuse fibrosis, diffuse atrophy, and periductal fibrosis predominantly found in elderly women suggested a relation with keratoconjunctivitis sicca in postmenopausal women. The authors speculate the periductal fibrosis is related to the decrease in tear fluid outflow with age and that interlobular ductal dilatation in the palpebral lobes may be caused by stenosis of the excretory duct in the fornix of conjunctiva. Ductal pathologic changes may be important in lacrimal gland dysfunction.

Dermatofibrosarcoma protuberans: An analysis of proliferative activity, DNA flow cytometry and p53 overexpression with emphasis on its progression

The aim of this study is to evaluate the degree and spectrum of malignancy of dermatofibrosarcoma protuberans (DFSP) in the aspect of proliferative activity, flow cytometric DNA analysis, and p53 immunoreactivity. Twenty‐three tumors from 19 cases of DFSP including three cases of DFSP with fibrosarcomatous areas (DFSP‐FS) were studied in comparison with its allied fibrohistiocytic tumors; that is, dermatofibroma (DF; 46 cases), fibrosarcoma (FS; four cases), and malignant fibrous histiocytoma (MFH; 11 cases). MIB‐1 labeling index (LI) of DFSP was significantly higher than that of DF and was lower than those of FS and of MFH. In ordinary DFSP, the recurrent tumors exhibited significantly higher MIB‐1 LI than that of the primary tumors, whereas the primary tumors showed almost the same proliferative activity of DF. DFSP‐FS tended to have a higher proliferative activity than DFSP without FS‐area (ordinary DFSP). In five of 19 cases of DFSP, aneuploidy (near‐diploidy) was found in four recurrent and one primary tumors. Immunohistochemical p53 overexpression was found in three of 19 cases of DFSP which also showed higher proliferative activity and aneuploidy. All cases of DF were immunohistochemically negative for p53, but most of the cases of FS and MFH were positive. Although DFSP has been classified in a category of fibrohistiocytic tumor of intermediate malignancy, the recurrent DFSP, DFSP‐FS, and DFSP with aneuploidy and/or p53 overexpression could be a subgroup of DFSP with more aggressive clinical behavior than ordinary primary ones.

Coexpression of hepatocyte growth factor and c‐Met proto‐oncogene product in synovial sarcoma

Hepatocyte growth factor (HGF) is a heterodlmeric polypep‐tide growth factor that has pleiotropic roles, Including those of mitogen, motogen and morphogen. The HGF receptor Is characterized as a c‐Met proto‐oncogene product (c‐Met), which is a heterodimeric tyrosine kinase receptor. Hepatocyte growth factor acts as a mediator between the mes‐enchymal and epithelial tissues because HGF is produced by mesenchymal cells and c‐Met is mainly expressed on various epithelial cells. Furthermore, the HGF/c‐Met system plays an important role in embryogenesis and the regeneration of various organs. Synovial sarcoma (SS) are unique sarcoma that show epithelial differentiation, but little is known about their histogenesis. The expression of HGF and c‐Met was examined by immunohlstochemlstry In SS specimens from 12 patients (six each of biphasic and monopha‐sic fibrous types). lmmunohistochemical coexpression of HGF and c‐Met was demonstrated in the epithelial component of five biphasic SS, while only c‐Met was expressed in the epithelioid nests of three monophasic fibrous SS. The spindle cell component was negative for HGF and c‐Met. In SS, positivity for epithelial markers, such as cytokeratins and epithelial membrane antigen, was diffusely observed in the epithelial component and was focally observed In spindle cells, while vlmentin was positive predominantly in the spindle cell component. The areas expressing HGF and c‐Met corresponded to distinct epithelial structures; however, HGF and c‐Met expression were not found in any other tumor cells expressing epithelial markers in the spindle cell component of SS. Considering the morphogenlc effect of HGF, which has been known to be one of Its most important roles, the unique immunohlstochemical localization of HGF and c‐Met In SS suggests that the HGF/c‐Met system may be closely related to the formatlon of epithellal (glandular) structures In biphasic SS.

Comparative study of fibrous dysplasia and osteofibrous dysplasia: Histopathological, immunohistochemical, argyrophilic nucleolar organizer region and DNA ploidy analysis

Fibrous dysplasia and osteofibrous dysplasia are both benign fibro‐osseous lesions of the bone. We retrospectively studied the clinicopathological findings in 90 cases of fibrous dysplasia and 17 cases of osteofibrous dysplasia. In these cases, the expression of proliferating cell nuclear antigen (PCNA) and the presence of argyrophilic nucleolar organizer regions (AgNOR), as well as DNA ploidy, were examined. The bones affected by fibrous dysplasia were the maxilla, femur and frontal bone. Osteofibrous dysplasia occurred exclusively in the tibia or fibula. The average age of patients with fibrous dysplasia (24.0 years) was higher than that of patients with osteofibrous dysplasia (12.9 years). Fibrous dysplasias were divided into four major histological subtypes: Pagetoid, Chinese alphabet, small bone and parallel bone. Bone lining cells, which are known as resting osteoblasts, were seen in some cases of fibrous dysplasia. Cartilage differentiation was not seen in osteofibrous dysplasia. PCNA expression was strongly positive in the nuclei of osteoblasts around the bone trabeculae in osteofibrous dysplasia, but negative in the nuclei of bone lining cells around the bone trabeculae in fibrous dysplasia. The number of AgNOR in osteofibrous dysplasia was slightly higher than that in fibrous dysplasia. Both fibrous dysplasia and osteofibrous dysplasia were diploid. These features suggest that fibrous dysplasia can be differentiated from osteofibrous dysplasia by anatomical site, patient age, histological appearance, cartilage differentiation and PCNA positivity. DNA content by image cytometry is not a useful tool for differentiating these two diseases.

The Frequency of Epidermal Growth Factor Receptor Mutation of Nonsmall Cell Lung Cancer according to the Underlying Pulmonary Diseases

Background. Although epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are effective in patients with nonsmall cell lung cancer with epidermal growth factor receptor (EGFR) mutation, EGFR-TKIs have a risk of inducing fatal interstitial lung disease (ILD). The selection of chemotherapy based on the EGFR mutation status is recommended, however, the frequency of EGFR mutation in patients with ILD and the efficacy and safety of EGFR-TKI in patients with ILD and EGFR mutation are unknown. Methods. We retrospectively reviewed the association of the EGFR mutation status of nonsmall cell lung cancer and pulmonary diseases. Based on high-resolution computed tomography (HRCT) performed at diagnosis of lung cancer, patients were categorized into three groups: normal, emphysema, and fibrosis. Results. Of 198 patients with nonsmall cell lung cancer, we identified 52 (26.3%) patients with an EGFR mutation. EGFR mutations were identified in 43 (35.2%) of 122 patients with normal lungs, 8 (13.6%) of 59 with emphysema, and 1 (5.9%) of 17 with pulmonary fibrosis. Of the 52 patients with EGFR mutation, 43 patients received gefitinib. One patient with an EGFR mutation and fibrosis developed fatal ILD. There was not a significant difference in median overall survival from gefitinib treatment between never-smokers and smokers (797 days versus not reached; P = 0.96). Conclusions. Patients with sensitive EGFR mutation and normal lungs may benefit from an EGFR-TKI treatment even if they have smoking history.

High rate of small TP53 mutations and infrequent loss of heterozygosity in malignant liver tumors associated with thorotrast : Implications for alpha-particle carcinogenesis

Epidemiological studies have revealed that malignant tumors occur in the liver approximately 20 years after injection of Thorotrast. We investigated genetic changes in the TP53 gene (formerly known as p53) in malignant liver tumors related to Thorotrast to cast light on the mechanisms of alpha-particle carcinogenesis. A total of 19 autopsy cases of liver malignancies [11 hepatocellular carcinomas (HCC), 5 cholangiocellular carcinomas (CCC) and 3 angiosarcomas (AS)] were analyzed. Using archival tissues, loss of heterozygosity (LOH) at the 17p13 locus was analyzed. Then single-strand conformation polymorphism analysis and sequencing were performed to detect mutations in exons 5 to 8 of the TP53 gene. As a result, 15 cases were informative in terms of polymorphism, and 4 cases showed LOH (3 HCC and 1 AS). Eight cases showed 9 mutations in exons and 2 in introns: 7 transitions (6 HCC and 1 CCC), 2 transversions (1 HCC and 1 AS), and 2 deletions (2 HCC). The direct action of alpha particles is thought to result in relatively large deletions such as those detected by LOH. Therefore, the low frequency of such changes (27%) compared to point mutations (47%) suggests that the genetic changes in the TP53 gene in the liver tumors related to Thorotrast were not caused mainly by direct actions of alpha particles but rather by indirect effects that may have been due to cycles of necrosis and regeneration.

Brain metastasis effectively treated with erlotinib following the acquisition of resistance to gefitinib: a case report

IntroductionNon-small-cell lung cancer harboring an activated epidermal growth factor receptor mutation exhibits a good response to epidermal growth factor receptor-tyrosine kinase inhibitors; however, clinicians often experience treatment failure following the development of resistance to epidermal growth factor receptor-tyrosine kinase inhibitor.Case presentationWe here report a case of a 56-year-old Japanese woman with non-small-cell lung carcinoma with a secondary T790M mutation associated with resistance to epidermal growth factor receptor-tyrosine kinase inhibitor that maintained sensitivity of brain metastases to epidermal growth factor receptor-tyrosine kinase inhibitor. An autopsy showed that the primary focus had a T790M mutation; however, no mutations of T790M were found in the brain metastases.ConclusionThis case demonstrates the detection of T790M was associated with the clinical responsiveness to epidermal growth factor receptor-tyrosine kinase inhibitor.