Published papers

PURPOSE: The majority of gastrointestinal stromal tumors (GIST) can be cured by surgery alone, but relapse occurs in 20% to 40% of cases. GISTs are considered to invariably arise through gain of function KIT or PDGFA mutation of the interstitial cells of Cajal (ICC). However, the genetic basis of the malignant progression of GISTs are poorly understood. PATIENTS AND METHODS: The expression levels of 54,613 probe sets in 32 surgical samples of untreated GISTs of the stomach and small intestine were analyzed with oligonucleotide microarrays. The representative GeneChip data were validated by real-time reverse transcriptase polymerase chain reaction and immunohistochemistry. RESULTS: Unbiased hierarchical clustering consistently separated the 32 cases of GIST into two major classes according to tumor site. The two major classes were further separated into novel subclasses, which were significantly correlated with various pathological prognostic parameters, the frequency of metastasis (P < .05), and clinical outcome. Immunohistochemical analysis of 152 independent patients with gastric GISTs revealed that the expression of dipeptidyl peptidase IV (T-cell activation antigen CD26) protein was significantly associated with poorer overall and disease-free survival (P < .00001). CONCLUSION: CD26 appears to be a reliable biomarker of malignant GISTs of the stomach. The postoperative recurrence rate of CD26-negative cases was as low as 2.0% (two of 102). Therefore, postoperative follow-up of such patients might be made less intensive. CD26 may play an important role in the malignant progression of gastric GISTs and serve as a therapeutic target.

Bone and soft tissue sarcomas (BSTSs) are rare malignant tumors of mesenchymal origin. Although BSTSs frequently occur in some hereditary cancer syndromes with germline mutations of DNA repair genes, genetic factors responsible for sporadic cases have not been determined. In the present study we undertook a case-control study and analyzed possible associations between the susceptibility to BSTS and the single nucleotide polymorphisms (SNPs) in DNA repair genes. Genomic DNAs extracted from case and control peripheral blood leukocytes were genotyped by pyrosequencing. For candidate polymorphisms, we chose 50 non-synonymous missense SNPs, which we have previously been identified by resequencing 36 DNA repair genes among the Japanese population. In the first screening, we analyzed 240 cases and 685 controls and selected six SNPs at the significance level of P < 0.1 (Fisher's exact test). The six SNPs were further analyzed in the second genotyping on an additional set of 304 cases and 834 controls. In the joint analysis (the first and second genotyping combined) of 544 cases and 1378 controls, Cys1367Arg of the WRN gene was found to be a protective factor of BSTS (odds ratio = 0.66, 95% confidence interval = 0.49-0.88, P = 0.005). An exploratory subgroup analysis without multiple comparison adjustment suggested that the WRN-Cys1367Arg SNP is associated with soft tissue sarcomas, sarcomas with reciprocal chromosomal translocations and malignant fibrous histiocytoma.

In soft tissue sarcomas, the diagnosis of malignant fibrous histiocytoma (MFH) has been a very controversial issue, and MFH is now considered to be reclassified into pleomorphic subtypes of other sarcomas. To characterize MFH genetically, we used an oligonucleotide microarray to analyze gene expression in 105 samples from 10 types of soft tissue tumors. Spindle cell and pleomorphic sarcomas, such as dedifferentiated liposarcoma, myxofibrosarcoma, leiomyosarcoma, malignant peripheral nerve sheath tumor (MPNST), fibrosarcoma and MFH, showed similar gene expression patterns compared to other tumors. Samples from those five sarcoma types could be classified into respective clusters based on gene expression by excluding MFH samples. We calculated distances between MFH samples and other five sarcoma types (dedifferentiated liposarcoma, myxofibrosarcoma, leiomyosarcoma, MPNST and fibrosarcoma) based on differentially expressed genes and evaluated similarities. Three of the 21 MFH samples showed marked similarities to one of the five sarcoma types, which were supported by histological findings. Although most of the remaining 18 MFH samples showed little or no histological resemblance to one of the five sarcoma types, 12 of them showed moderate similarities in terms of gene expression. These results explain the heterogeneity of MFH and show that the majority of MFHs could be reclassified into pleomorphic subtypes of other sarcomas. Taken together, gene expression profiling could be a useful tool to unveil the difference in the underlying molecular backgrounds, which leads to a rational taxonomy and diagnosis of a diverse group of soft tissue sarcomas.

BACKGROUND: Clear cell sarcoma (CCS) of tendons and aponeuroses (malignant melanoma of soft parts) is a rare melanocytic soft tissue sarcoma. The objective of this study was to determine the clinical features, prognostic factors, and optimal treatment policy for patients with this rare disease. METHODS: Seventy-five consecutive patients with histologically confirmed CCS who received treatment between 1980 and 2004 were analyzed retrospectively. RESULTS: There were 41 men and 34 women, and the median age was 36 years. Sixty-five tumors were located in the extremities, and 10 tumors were located in the trunk. The median tumor size was 4 cm. Seventy-one patients underwent surgical excision, and 56 patients received chemotherapy. Sixteen patients developed local recurrences, and 52 patients developed metastasis. The overall patient survival rates was 47% at 5 years and 36% at 10 years. Univariate analysis showed that sex (P = .018), tumor size (P = .001), tumor depth (P = .002), TNM classification (P = .001), and surgical margin (P = .042) were significant prognostic factors. Among the 52 patients who presented with localized disease, sex (P = .023), tumor size (P = .002), tumor depth (P = .011), TNM classification (P = .004), and chemotherapy (P = .032) were identified as significant prognostic factors. Multivariate analysis showed that tumor size remained an independent prognostic factor in both groups. CONCLUSIONS: The current results supported the contention that early diagnosis and initial wide excision are essential for a favorable outcome of CCS. The role of chemotherapy for CCS should be investigated further.

OBJECTIVE: The purpose of this study is to identify factors that affect survival of patients with differentiated thyroid carcinoma with bone metastases and to optimize surgical treatment modality for bone metastatic lesion by comparing duration of patient survival and local control. METHODS: We examined 52 bone metastatic lesions from 40 patients with differentiated thyroid carcinoma who were treated surgically between 1994 and 2008 at Keio University Hospital. Median follow-up time was 46 months (range: 4-233 months). Patients' disease-specific survival, local control duration and factors that potentially affected disease-specific survival after bone metastasis surgery were statistically analyzed. RESULTS: The 2-, 5- and 10-year disease-specific survival rates were 77.2, 64.3 and 45.7%, respectively. Factors that were significantly associated with poor survival rates in multivariate analyses included age at bone metastasis surgery >/=65 years (P = 0.0068), time from diagnosis of primary cancer to bone metastasis surgery >/=5 years (P = 0.0018) and presence of visceral metastases (P = 0.0092). The 2-, 5- and 10-year local control rates in our series were 91.4, 72.7 and 63.6%, respectively. The 5-year local control rates for radical and palliative surgery were 84.4 and 55.3%, respectively, and differed significantly (P = 0.019). CONCLUSIONS: Because disease-specific survival of patients with differentiated thyroid carcinoma is fairly good, inadequate treatment of bone metastatic lesions can result in severe disabilities. Therefore, radical surgery for bone metastatic lesions should be considered, especially for those with favorable prognostic factors.

Desmoplastic fibroma (DF) of the bone is a rare locally aggressive tumor usually occurring in adolescents and young adults. These tumors most commonly occur in the mandibles and metaphyses of long bones but are extremely rare in small bones, often resulting in diagnostic problems. The occurrence of these tumors in the foot is especially limited. We report the clinical, radiographic, and histologic features of DF arising in the distal phalanx of the great toe and a review of the published data.

Aneurysmal bone cyst (ABC) is a rare benign cystic lesion of the bone that composes 1-2% of the entire bone tumors. Some are idiopathic, and some occur secondary to other tumors such as giant cell tumor and chondroblastoma. In this article, we report the clinical, radiographic, and histological findings of a secondary ABC following chondroblastoma of the patella with a review of the literature.

The diagnosis and treatment of soft tissue sarcomas (STSs) has been particularly difficult, because STSs are a group of highly heterogeneous tumors in terms of histopathology, histological grade, and primary site. Recent advances in genome technologies have provided an excellent opportunity to determine the complete biological characteristics of neoplastic tissues, resulting in improved diagnosis, treatment selection, and investigation of therapeutic targets. We had previously developed a novel bioinformatics method for marker gene selection and applied this method to gene expression data from STS patients. This previous analysis revealed that the extracted gene combination of macrophage migration inhibitory factor (MIF) and stearoyl-CoA desaturase 1 (SCD1) is an effective diagnostic marker to discriminate between subtypes of STSs with highly different outcomes. In the present study, we hypothesize that the combination of MIF and SCD1 is also a prognostic marker for the overall outcome of STSs. To prove this hypothesis, we first analyzed microarray data from 88 STS patients and their outcomes. Our results show that the survival rates for MIF- and SCD1-positive groups were lower than those for negative groups, and the p values of the log-rank test are 0.0146 and 0.00606, respectively. In addition, survival rates are more significantly different (p = 0.000116) between groups that are double-positive and double-negative for MIF and SCD1. Furthermore, in vitro cell growth inhibition experiments by MIF and SCD1 inhibitors support the hypothesis. These results suggest that the gene set is useful as a prognostic marker associated with tumor progression.

The epithelial-mesenchymal transition (EMT) contributes to the malignant progression of cancer cells including acquisition of the ability to undergo metastasis. However, whereas EMT-related transcription factors (EMT-TF) are known to play an important role in the malignant progression of epithelial tumors, their role in mesenchymal tumors remains largely unknown. We show that expression of the gene for Twist2 is downregulated in human osteosarcoma and correlates inversely with tumorigenic potential in mouse osteosarcoma. Forced expression of Twist2 in highly tumorigenic murine osteosarcoma cells induced a slight inhibition of cell growth in vitro but markedly suppressed tumor formation in vivo. Conversely, knockdown of Twist2 in osteosarcoma cells with a low tumorigenic potential promoted tumor formation in vivo, suggesting that Twist2 functions as a tumor suppressor in osteosarcoma cells. Furthermore, Twist2 induced expression of fibulin-5, which has been reported as a tumor suppressor. Medium conditioned by mouse osteosarcoma cells overexpressing Twist2 inhibited expression of the MMP9 gene as well as invasion in mouse embryonic fibroblasts, and forced expression of Twist2 in osteosarcoma cells suppressed MMP9 gene expression in tumor tissue. Data from the present study suggest that Twist2 inhibits formation of a microenvironment conducive to tumor growth and thereby attenuates tumorigenesis in osteosarcoma.

Myxoid/round cell liposarcoma (MRCL), unlike other soft tissue sarcomas, has been associated with unusual pattern of metastasis to extrapulmonary sites. In an attempt to elucidate the clinical features of MRCL with metastatic lesions, 58 cases, from the medical database of Keio University Hospital were used for the evaluation. 47 patients (81%) had no metastases, whereas 11 patients (11%) had metastases during their clinical course. Among the 11 patients with metastatic lesions, 8 patients (73%) had extrapulmonary metastases and 3 patients (27%) had pulmonary metastases. Patients were further divided into three groups; without metastasis, with extrapulmonary metastasis, and with pulmonary metastasis. When the metastatic patterns were stratified according to tumor size, there was statistical significance between the three groups (P = 0.028). The 8 cases with extrapulmonary metastases were all larger than 10 cm. Similarly, histological grading had a significant impact on metastatic patterns (P = 0.027). 3 cases with pulmonary metastatic lesions were all diagnosed as high grade. In conclusion, large size and low histological grade were significantly associated with extrapulmonary metastasis.

Mesenchymal chondrosarcoma (MC) is an extremely rare subtype of chondrosarcoma. A tumor specific fusion gene, HEY1-NCOA2 fusion, was recently identified in this tumor. The finding raises the possibility that the diagnosis of MC can be improved by examining the fusion gene. In the present study, we aimed to evaluate the efficacy of fluorescence in situ hybridization (FISH) in detecting HEY1-NCOA2 fusion for the diagnosis of MC. Specimens from 10 patients diagnosed with MC were used for the study. Dual-color FISH was performed using two different probes that specifically hybridize to HEY1 and NCOA2, respectively. Fusion signals were identified in all but two specimens, in which no signal was detected, presumably because of inadequate sample preparation. In accordance with results of a previous study, FISH analysis was highly sensitive in detecting HEY1-NCOA2 fusion in adequately prepared MC samples. The current study adds further support for the use of HEY1-NCOA2 fusion as a valid diagnostic marker for MC.

Synovial sarcoma is an aggressive soft tissue sarcoma with only a modest response to conventional cytotoxic agents. In the present study, we evaluated the potential antitumor effects of a novel anti-angiogenesis agent, pazopanib, against synovial sarcoma cells. We found that pazopanib directly inhibited the growth of synovial sarcoma cells by inducing G1 arrest. Multiplex analyses revealed that the PI3K-AKT pathway was highly suppressed in pazopanib-sensitive synovial sarcoma cells. Furthermore, administration of pazopanib highly suppressed the tumor growth in a xenograft model. Taken together, these results suggest pazopanib as a possible agent against synovial sarcoma and may warrant further clinical studies.

BACKGROUND: Anaplastic transformation of differentiated thyroid carcinoma (DTC) is a rare event with a poor clinical outcome. It usually occurs in the primary site or in regional lymph nodes, but rarely in distant metastatic lesions. SUMMARY: A 55-year-old woman with persistent pain in the left hip joint visited our hospital. She had a history of DTC that had been surgically removed 12 years earlier. Clinical images showed a tumorous mass in the left pelvis, indicative of bone metastasis. The patient underwent surgery to remove the tumor and remained stable until local recurrence was found 5 weeks after the surgery. The patient subsequently underwent radiation therapy; however, she died of respiratory failure due to lung metastases 2 months after the surgery for the recurrent lesion. The surgical specimens were diagnosed as anaplastic thyroid carcinoma, indicating that anaplastic transformation of thyroid follicular carcinoma occurred in the metastatic skeletal lesion. In addition, the patient had an unusually high white blood cell count throughout the course. Based on elevated serum granulocyte colony-stimulating factor (G-CSF) levels and positive immunostaining for G-CSF in the surgical specimens, the patient was diagnosed with paraneoplastic leukocytosis. CONCLUSION: To our knowledge, this is the first case of anaplastic transformation of DTC arising in a metastatic bone lesion described in the literature. In addition, the present case also exhibited severe leukocytosis accompanied by elevated serum G-CSF levels. Clinicians should be aware of the possibility of this occurring in their patients with DTC, as this development calls for a rapid change from observational follow-up to aggressive treatment.

We aimed to develop prognostic biomarkers for synovial sarcoma employing a proteomic approach. We examined the proteomic profile of synovial sarcoma using two-dimensional difference gel electrophoresis (2D-DIGE). We identified 20 protein spots whose intensity was statistically different (p<0.01) between a group of eight patients who were alive and continuously disease-free for over five years and a group of five patients who died of the disease within two years post diagnosis. Mass spectrometric protein identification demonstrated that these 20 spots corresponded to 17 distinct gene products. Three of the 20 spots corresponded to secernin-1 and had higher intensity in the good prognosis group. The prognostic performance of secernin-1 was further examined immunohistochemically in 45 synovial sarcoma cases. The 5-year survival rate was 77.6% and 21.8% for patients with secernin-1 positive and negative primary tumors respectively (p=0.0015). The metastasis-free survival was significantly higher in the patient group with high secernin-1 expression compared to that with low expression (p=0.0012). Uni- and multivariate analyses revealed that secernin-1 expression was a powerful prognostic factor compared to other clinico-pathological parameters examined. These results indicate that secernin-1 may be used as a biomarker to predict the overall and metastasis-free survival in synovial sarcoma patients.

Poorly differentiated type synovial sarcoma (PDSS) is a variant of synovial sarcoma characterized by predominantly round or short-spindled cell morphology. Although accumulating evidence from clinicopathologic studies suggests a strong association between this variant of synovial sarcoma and poor prognosis, little has been reported on the molecular basis of PDSS. To gain insights into the mechanism(s) that underlie the emergence of PDSS, we analyzed the gene expression profiles of 34 synovial sarcoma clinical samples, including 5 cases of PDSS, using an oligonucleotide microarray. In an unsupervised analysis, the 34 samples fell into 3 groups that correlate closely with histologic subtypes: monophasic, biphasic, and poorly differentiated types. PDSS was characterized by down-regulation of genes associated with neuronal and skeletal development and cell adhesion. Moreover, upregulation of genes on a specific chromosomal locus, 8q21.11, was identified. This locus-specific transcriptional activation in PDSS was confirmed by reverse transcriptase-PCR analysis of 9 additional synovial sarcoma samples. Our results indicate that PDSS tumors constitute a distinct group based on expression profiles.

The development of cancer is due to the growth and proliferation of transformed normal cells. Recent evidence suggests that the nature of oncogenic stress and the state of the cell of origin critically affect both tumorigenic activity and tumor histological type. However, this mechanistic relationship in mesenchymal tumors is currently largely unexplored. To clarify these issues, we established a mouse osteosarcoma (OS) model through overexpression of c-MYC in bone marrow stromal cells (BMSCs) derived from Ink4a/Arf (-/-) mice. Single-cell cloning revealed that c-MYC-expressing BMSCs are composed of two distinctly different clones: highly tumorigenic cells, similar to bipotent-committed osteochondral progenitor cells, and low-tumorigenic tripotent cells, similar to mesenchymal stem cells (MSCs). It is noteworthy that both bipotent and tripotent cells were capable of generating histologically similar, lethal OS, suggesting that both committed progenitor cells and MSCs can become OS cells of origin. Shifting mesenchymal differentiation by depleting PPARgamma in tripotent MSC-like cells and overexpressing PPARgamma in bipotent cells affected cell proliferation and tumorigenic activity. Our findings indicate that differentiation potential has a key role in OS tumorigenic activity, and that the suppression of adipogenic ability is a critical factor for the development of OS.

The diagnosis and treatment of soft tissue sarcomas (STS) have been difficult. Of the diverse histological subtypes, undifferentiated pleomorphic sarcoma (UPS) is particularly difficult to diagnose accurately, and its classification per se is still controversial. Recent advances in genomic technologies provide an excellent way to address such problems. However, it is often difficult, if not impossible, to identify definitive disease-associated genes using genome-wide analysis alone, primarily because of multiple testing problems. In the present study, we analyzed microarray data from 88 STS patients using a combination method that used knowledge-based filtering and a simulation based on the integration of multiple statistics to reduce multiple testing problems. We identified 25 genes, including hypoxia-related genes (e.g., MIF, SCD1, P4HA1, ENO1, and STAT1) and cell cycle- and DNA repair-related genes (e.g., TACC3, PRDX1, PRKDC, and H2AFY). These genes showed significant differential expression among histological subtypes, including UPS, and showed associations with overall survival. STAT1 showed a strong association with overall survival in UPS patients (logrank p = 1.84 x 10(-6) and adjusted p value 2.99 x 10(-3) after the permutation test). According to the literature, the 25 genes selected are useful not only as markers of differential diagnosis but also as prognostic/predictive markers and/or therapeutic targets for STS. Our combination method can identify genes that are potential prognostic/predictive factors and/or therapeutic targets in STS and possibly in other cancers. These disease-associated genes deserve further preclinical and clinical validation.