Taketo Okubo

Gene Expression Network Analysis of ETV1 Reveals KCTD10 as a Novel Prognostic Biomarker in Gastrointestinal Stromal Tumor

Background Prognostic biomarkers are required for risk stratification therapy in the patients with gastrointestinal stromal tumor (GIST). In this study, we aimed to identify prognostic biomarkers in GIST. We assessed the prognostic value of E twenty-six variant 1 (ETV1), a recently identified transcription factor unique to GIST. We also examined the clinical utility and functions of its downstream gene, potassium channel tetramerization domain containing protein 10 (KCTD10). Methods The levels of ETV1 and KCTD10 were evaluated immunohistochemically in 112 patients with GIST treated at two hospitals. The functional properties of KCTD10 were examined by gene silencing assay in cultured GIST cells. Results Immunohistochemistry revealed that ETV1 expression in GIST had no prognostic significance. In contrast, the disease-free survival rate was 88.5% in patients with KCTD10-positive tumors and 55.8% in those with KCTD10-negative tumors (p <0.0001). KCTD10 was an independent prognostic factor (p <0.05). In the low-risk classification group, KCTD10 was significantly associated with favorable prognosis (p = 0.0008). Gene silencing of KCTD10 increased cell proliferation and invasion, suggesting that KCTD10 has a tumor-suppressive function. Conclusions The GIST-specific transcription factor ETV1 may have no prognostic potential, whereas its downstream gene KCTD10 is associated with a favorable prognosis. Our study indicated the novel prognostic utility of KCTD10 in GIST, and suggested its tumor-suppressive effects on GIST cells. Further validation studies of KCTD10 for clinical applications, and functional verification of KCTD10 for better understanding of molecular basis of malignant phenotypes are worth challenging in GIST.

A case of secondary malignant giant-cell tumor of bone with p53 mutation after long-term follow-up.

A 46-year-old man was admitted to the hospital with a recurrent giant-cell tumor of the distal femur. This was his fourth recurrence, and it had occurred 16 years after his last treatment. The resected recurrent tumor was histologically determined to be a conventional giant-cell tumor. However, a single lung metastatic lesion and local recurrence were noticed 6 months after the resection, both of which were surgically excised. The lung lesion was histologically determined to be an implantation of giant-cell tumor, whereas the local recurrent lesion contained a clearly separated fibrosarcomatous area within the conventional giant-cell tumor. Immunohistochemistry showed diffuse and strong p53 expression in the fibrosarcomatous area. Direct sequencing revealed a p53 mutation in the sarcomatous area and a recessive mutant signal in the conventional area. The lung lesion also contained the same p53 mutation. Identification of the p53 mutation may help in diagnosing potential malignant transformation of giant-cell tumor.

Intraneural lipomatous tumor of the median nerve: Three case reports with a review of literature

INTRODUCTION Intraneural lipoma and fibrolipomatous hamartoma of the nerve are rare soft tissue tumors that most commonly occur in the forearm and the wrist, and particularly within the median nerve. When the lesions are large enough, they may cause progressive compression neuropathy. They are distinct entities each other with different clinical and radiological findings and thereby need different surgical treatments. PRESENTATION OF CASE We report here 3 cases of intraneural lipomatous tumors of the median nerve (1 case of intraneural lipoma and 2 cases of fibrolipomatous hamartoma). DISCUSSION All patients were surgically treated successfully with complete excision for intraneural lipoma and with carpal tunnel releases for the both fibrolipomatous hamartomas. CONCLUSION A careful preoperative planning is necessary for the optimal treatment by distinguishing whether it is a resectable or non-resectable tumor based on the clinical and radiological findings, because they have characteristic findings each other.

Validation Study on Pfetin and ATP-dependent RNA Helicase DDX39 as Prognostic Biomarkers in Gastrointestinal Stromal Tumour

OBJECTIVE This study aimed to validate two prognostic biomarkers, pfetin and adenosine triphosphate-dependent RNA helicase DDX39 (DDX39), in gastrointestinal stromal tumour. Prognostic biomarkers have long been required for the optimal use of kinase inhibitors in gastrointestinal stromal tumour. METHODS The expression level of pfetin was immunohistochemically examined in 72 gastrointestinal stromal tumour cases, being correlated with the clinicopathological parameters. Meta-analysis of the prognostic value of pfetin was performed in a total of 371 cases. The prognostic utility of the combination of pfetin and DDX39 was examined in the 72 gastrointestinal stromal tumour cases. RESULTS Immunohistochemical study demonstrated the disease-free survival rate to be 94.7% for pfetin-positive patients and 20.0% for pfetin-negative patients among the 72 gastrointestinal stromal tumour cases (P < 0.0001). In the 371 cases, the disease-free survival rate was 93.8% for pfetin-positive patients and 40.6% for pfetin-negative patients (P < 0.0001). Both univariate and multivariate analyses revealed that pfetin expression was an independent prognostic factor (P< 0.0001). When evaluated in combination with pfetin and DDX39, the disease-free survival rates were 0.0% for the pfetin-negative and DDX39-strong patients. CONCLUSIONS These results established the clinical utility of pfetin as a novel prognostic biomarker for gastrointestinal stromal tumour. The combined use of pfetin and DDX39 appeared to have powerful prognostic value. These biomarkers will be useful in deciding whether to administer adjuvant therapy after surgery.

A case of de novo secondary malignant giant-cell tumor of bone with loss of heterozygosity of p53 gene that transformed within a short-term follow-up

A 19-year-old woman was admitted to the hospital with a complaint of right wrist pain. A plain radiograph showed an osteolytic lesion in the right distal radius. Surgical treatment with curettage and bone grafting was performed under the clinical diagnosis of a giant-cell tumor. However, local recurrence was noticed 6 months after the treatment, and the curettage and bone graft were performed again. The histology of the recurrent lesion revealed a malignant giant-cell tumor that was entirely composed of highly atypical stromal cells and tumor giant cells. After a retrospective review of the primary lesion, it was found to also contain a small focus of pleomorphic cells within the conventional giant-cell tumor. Immunohistochemical and genetic analysis revealed p53 overexpression in the tumor giant cells and loss of heterozygosity of p53 gene only in the recurrent tumor; thus, a diagnosis of secondary malignant giant-cell tumor was finally made. The patient underwent systemic chemotherapy along with curettage and cryosurgery using liquid nitrogen. It is now 1 year and 4 months after the last treatment, and the patient is well and alive with no evidence of the disease. Identification of p53 genetic alteration may help in diagnosing malignant giant-cell tumor.

Skeletal Metastasis of Unknown Primary Origin at the Initial Visit: A Retrospective Analysis of 286 Cases

Background Skeletal metastasis is a common metastatic event for several carcinomas, and the treatment for skeletal metastasis of unknown primary (SMUP) are a critical issue in cancer therapy. Making a diagnosis of the primary site is the most crucial step in the treatment of SMUP; however, the procedures are sometimes difficult and time-consuming, and the primary site often remains unknown. Therefore, to establish optimal diagnostic strategies and elucidate the overall survival rates of SMUP, we conducted this retrospective study. Methods We retrospectively analyzed the clinical data for 286 SMUP cases from a total of 2,641 patients with skeletal metastases who were treated between 2002 and 2014 at our initiations. Results The primary sites were identified in 254/286 patients (88.8%), while 32 (11.2%) primary sites were not detected by our diagnostic strategies. Lung cancer was identified in 72 (25.2%) cases, and was the most frequently observed primary lesion. The median survival time of the SMUP patients was 20.0 months, while the median survival times of solitary bone metastasis cases and multi-bone metastasis cases were 39.0 months and 16.0 months, respectively. The median survival times of prostate cancer cases was over 120 months, that of patients with primary lung cancers was 9.0 months and the median survival time of cases who were finally diagnosed with an unknown primary was 11.0 months. Conclusions We believe that our study would contribute to establishing an optimal strategy for diagnosing the primary site in SMUP patients, and our data provide definite indications for the survival times for different SMUP situations.

The Prognostic Value of Pfetin: A Validation Study in Gastrointestinal Stromal Tumors Using a Commercially Available Antibody

OBJECTIVE Adjuvant treatment with imatinib mesylate is an effective treatment for gastrointestinal stromal tumor. However, 50% of patients with gastrointestinal stromal tumor can be cured by surgery alone; hence, risk stratification for therapy with imatinib mesylate is the next challenge. Previously, using a proteomic approach, we discovered a potential prognostic biomarker for gastrointestinal stromal tumor, pfetin, and immunohistochemically validated its clinical utility using our original monoclonal antibody. In the present study, we examine the usefulness of a commercially available polyclonal antibody against pfetin. METHODS Western blotting and immunohistochemistry were performed using surgical specimens of primary tissues from gastrointestinal stromal tumor patients using a polyclonal antibody against pfetin and our original monoclonal antibody. Formalin-fixed and paraffin-embedded primary tissue sections from 112 gastrointestinal stromal tumor patients were subjected to immunohistochemistry. The immunohistochemistry results were integrated with the clinico-pathological observations. RESULTS Western blotting revealed that both antibodies recognized multiple post-translationally modified pfetin isoforms. The immunohistochemical study with the commercial antibody demonstrated that the disease-free survival rate was 88 and 56% for pfetin-positive and pfetin-negative patients, respectively. Univariate and multivariate analyses showed that pfetin expression as measured by the commercial antibody was a significant and independent prognostic factor among the clinico-pathological parameters examined. Of the 112 gastrointestinal stromal tumor cases examined, 13 yielded discordant results between the commercial antibody and our original antibody, and there were no significantly different clinical or pathological factors to account for this discrepancy. CONCLUSIONS Our observations suggest that the pfetin expression level assessed by the commercial antibody could be a prognostic biomarker in gastrointestinal stromal tumors.

Clinicopathological effects of protein phosphatase 2, regulatory subunit A, alpha mutations in gastrointestinal stromal tumors

Recently, several studies have reported that dysfunctions in protein phosphatase 2A (PP2A) caused by alterations in protein phosphatase 2 regulatory subunit A, alpha (PPP2R1A) are responsible for tumorigenesis and tumor progression in several types of cancers. The impact of PPP2R1A mutations remains unknown in gastrointestinal stromal tumors (GISTs), although mutations in KIT and PDGFRA, which result in constitutive activation of the receptor tyrosine kinase pathway, are important in GIST tumorigenesis. In this study, we performed mutation analysis of PPP2R1A to examine the frequency of PPP2R1A mutations and their clinicopathological correlation in 94 GIST cases. In addition, we performed an in vitro analysis to investigate the effects of PPP2R1A mutations on cell proliferation and kinase phosphorylation in GIST cells. Seventeen GIST cases (18%) harbored mutations in PPP2R1A. All but one of these 17 cases harbored a KIT, PDGFRA, HRAS, NRAS, or KRAS mutation as the oncogenic driver mutation, and the remaining case was immunohistochemically negative for succinate dehydrogenase B (SDHB). Multivariate analysis showed that larger tumor size, higher mitotic rate, and PPP2R1A mutation are independent prognostic factors for overall survival; however, PPP2R1A mutation was not an independent prognostic factor for disease-free survival. The transduction of GIST cells with mutant PPP2R1A induced an accelerated growth rate via increased phosphorylation of Akt1/2, ERK1/2, and WNK1, a kinase associated with angiogenesis. In addition, the transduction of GIST cells with mutant PPP2R1A caused increased c-kit phosphorylation, suggesting that c-kit is also a target of PP2A, reinforcing the tumorigenic capabilities of c-kit. Furthermore, the transducing GIST cells with wild-type PP2A dephosphorylated mutant c-kit. This study provides a new insight into the biology of GISTs and their phosphatase activity, and activated PP2A could be a therapeutic target in GISTs.

Protein Expression Profiling of Giant Cell Tumors of Bone Treated with Denosumab

Giant cell tumors of bone (GCTB) are locally aggressive osteolytic bone tumors. Recently, some clinical trials have shown that denosumab is a novel and effective therapeutic option for aggressive and recurrent GCTB. This study was performed to investigate the molecular mechanism underlying the therapeutic effect of denosumab. Comparative proteomic analyses were performed using GCTB samples which were taken before and after denosumab treatment. Each expression profile was analyzed using the software program to further understand the affected biological network. One of identified proteins was further evaluated by gelatin zymography and an immunohistochemical analysis. We identified 13 consistently upregulated proteins and 19 consistently downregulated proteins in the pre- and post-denosumab samples. Using these profiles, the software program identified molecular interactions between the differentially expressed proteins that were indirectly involved in the RANK/RANKL pathway and in several non-canonical subpathways including the Matrix metalloproteinase pathway. The data analysis also suggested that the identified proteins play a critical functional role in the osteolytic process of GCTB. Among the most downregulated proteins, the activity of MMP-9 was significantly decreased in the denosumab-treated samples, although the residual stromal cells were found to express MMP-9 by an immunohistochemical analysis. The expression level of MMP-9 in the primary GCTB samples was not correlated with any clinicopathological factors, including patient outcomes. Although the replacement of tumors by fibro-osseous tissue or the diminishment of osteoclast-like giant cells have been shown as therapeutic effects of denosumab, the residual tumor after denosumab treatment, which is composed of only stromal cells, might be capable of causing bone destruction; thus the therapeutic application of denosumab would be still necessary for these lesions. We believe that the protein expression patterns and the results of the network analysis will provide a better understanding of the effects of denosumab administration in patients with GCTB.

Low-grade myofibroblastic sarcoma of the distal femur

INTRODUCTION Low-grade myofibroblastic sarcoma (myofibrosarcoma) is described to be a distinct atypical myofibroblastic tumor often with fibromatosis-like features and predilection for head and neck. Low-grade myofibroblastic sarcoma of bone is extremely rare. PRESENTATION OF CASE A 50-year-old woman was admitted to our hospital because she had experienced right knee pain for 2 years. Plain radiography showed a honeycombed lesion on the right distal femur, and computed tomography showed a bone tumor with cortex destruction invading the soft tissue. A biopsy specimen from the intraosseous lesion showed a hypocellular area of spindle cell proliferation with dense collagen deposition, which is reminiscent of a histological feature of desmoplastic fibroma. However, histological examination of the extraosseous lesion indicated a slightly hypercellular area containing scattered spindle-shaped atypical cells with enlarged nuclei, suggestive of low-grade sarcoma. Spindle-shaped atypical cells were immunohistochemically positive for SMA. A final diagnosis of low-grade myofibroiblastic sarcoma of the bone was made from a surgically resected specimen. DISCUSSION The patient was alive and well with no evidence of disease at 15 months after the surgery without any additional therapy. CONCLUSION Extensive sampling of a tumor may be necessary to determine the true nature of the tumor and to make an accurate diagnosis.