Keisuke Akaike

Distinct clinicopathological features of NAB2-STAT6 fusion gene variants in solitary fibrous tumor with emphasis on the acquisition of highly malignant potential

The impact of NGFI-A binding protein 2 (NAB2)-signal transducer and activator of transcription 6 (STAT6) fusion on the biological behavior and the mechanism of acquisition of malignant phenotype in solitary fibrous tumor (SFT) is not well understood. We examined variations of the NAB2-STAT6 fusion gene in 40 cases of SFT using formalin-fixed, paraffin-embedded tissues and secondary genetic alterations of tumor protein p53 (TP53),, platelet-derived growth factor receptor, β polypeptide (PDGFRB), and telomerase reverse transcriptase (TERT) promoters. These gene variations were compared with the clinicopathological features. The 2-year and 5-year disease-free survival rates (DFSRs) were 91% and 83%, respectively. All 40 samples demonstrated nuclear staining for STAT6, including CD34-negative cases. Moreover, p53-positive staining was associated with a lower DFSR and was significantly associated with higher Ki-67 label index, higher mitotic rate (mitosis, >4/high-power field), and the presence of nuclear atypia/pleomorphism. NAB2-STAT6 fusions were detected in all of the cases; the NAB2 exon 4-STAT6 exon 2, the most common genotype, appeared in 18 cases, which was associated with thoracic tumor location and the less aggressive phenotype. In contrast, tumors with NAB2 exon 6-STAT6 exon 16/18 demonstrated an aggressive phenotype. Mutations in TP53 and PDGFRB were detected in 2 and 3 cases respectively, and these occurred in a mutually exclusive fashion. TERT promoter hot spot mutations were observed in 5 cases, which were associated with shorter DFSR. Two dedifferentiated SFT cases harbored both TP53 and TERT promoter mutations. TP53 mutations, which result in its overexpression, in combination with TERT promoter mutations seem to play an important role in the dedifferentiation process.

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.

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.

Reduced argininosuccinate synthetase expression in refractory sarcomas: Impacts on therapeutic potential and drug resistance

Background Treating drug-resistant sarcomas remains a major challenge. The present study aimed to identify a novel therapy for drug-resistant sarcomas based on metabolic errors involving argininosuccinate synthetase1 (ASS1). Results ASS1 expression was reduced in Dox-resistant sarcoma cells. Immunohistochemistry and real-time PCR showed an inverse correlation between ASS1 and P-gp expressions. The inhibition of cellular proliferation with G1-arrest was shown to lead to autophagy with arginine deprivation. In addition, the combination of an autophagy inhibitor plus arginine deprivation was more effective than arginine deprivation alone. In cells with suppressed ASS1 expression, P-gp expression was upregulated as compared to that in negative controls. Discussion These results indicate that the reduced ASS1 expression in Dox-resistant sarcomas may contribute to drug resistance in association with the expression of P-gp. ASS1 deficiency is a potential target for novel drug therapies. The combination of arginine-deprivation therapy and an autophagy inhibitor may have anti-tumor effects in refractory sarcomas. Methods We assessed the expressions of ASS1 and P-glycoprotein (P-gp) in clinical specimens and cell lines of osteosarcoma (KHOS), doxorubicin (Dox)-resistant osteosarcoma (KHOSR2), epithelioid sarcomas (ES-X and VAESBJ) and alveolar soft part sarcoma (ASPS-KY). Each cell line was cultured in arginine-containing and arginine-free media. Cell growth was assessed using an XTT assay and flow cytometry. We analyzed the induction of autophagy in arginine-free medium. Moreover, we assessed the expression of P-gp after suppressing ASS1 in Dox-sensitive cells (MCF-7 and KHOS) and after transfecting ASS1 into Dox-resistant cells (ES-X, VAESBJ, ASPS-KY and KHOSR2).

Expression of F-actin-capping protein subunit beta, CAPZB, is associated with cell growth and motility in epithelioid sarcoma

BackgroundA previous proteomics study demonstrated the overexpression of F-actin capping protein subunit beta (CAPZB) in tissue specimens of epithelioid sarcoma (EpiS). The aim of the present study was to elucidate the function of CAPZB in EpiS.MethodsCellular functional assays were performed in two EpiS cell lines using CAPZB siRNAs. In addition, comparative protein expression analyses using Isobaric Tags for Relative and Absolute Quantitation (i-TRAQ) method were performed to identify the specific proteins whose expression was dysregulated by CAPZB, and analysed the data with the Ingenuity Pathways Analysis (IPA) system using the obtained protein profiles to clarify the functional pathway networks associated with the oncogenic function of CAPZB in EpiS. Additionally, we performed functional assays of the INI1 protein using INI1-overexpressing EpiS cells.ResultsAll 15 EpiS cases showed an immunohistochemical expression of CAPZB, and two EpiS cell lines exhibited a strong CAPZB expression. Silencing of CAPZB inhibited the growth, invasion and migration of the EpiS cells. Analysis of protein profiles using the IPA system suggested that SWI/SNF chromatin-remodeling complexes including INI1 may function as a possible upstream regulator of CAPZB. Furthermore, silencing of CAPZB resulted in a decreased expression of INI1 proteins in the INI1-positive EpiS cells, whereas the induction of INI1 in the INI1-deficient EpiS cells resulted in an increased CAPZB mRNA expression.ConclusionsCAPZB is involved in tumor progression in cases of EpiS, irrespective of the INI1 expression, and may be a potential therapeutic target. The paradoxical relationship between the tumor suppressor INI1 and the oncoprotein CAPZB in the pathogenesis of EpiS remains to be clarified.

Mast cell sarcoma of the sternum, clonally related to an antecedent germ cell tumor with a novel D579del KIT mutation

Mastocytosis is a heterogeneous disease characterized by the accumulation of abnormal mast cells. The disease is classified as either cutaneous or systemic mastocytosis based on the site of mast cell accumulation [1]. Two forms of systemic mastocytosis are known, namely extracutaneousmastocytoma and mast cell sarcoma. Both form a localized mass in non-cutaneous organs. Mastocytomas are non-destructive and show a benign course, while mast cell sarcomas cause destructive proliferation and malignant progression. Mast cell neoplasms frequently have KIT mutations. The D816V mutation in exon 17 has often been observed in systemic mastocytosis [1]. However, mast cell sarcoma is a rare disease, and there have been few reports regarding KIT mutation status in this malignancy [2–10]. There have been no previous reports in the literature regarding the KIT D816V mutation in mast cell sarcoma and only two reports of a KIT exon 17 mutation in mast cell sarcoma [11, 12]. As aggressive systemic mastocytosis may be treated with a tyrosine kinase inhibitor (TKI) [13], determining the KIT mutation status in mast cell sarcoma is important to support decisions on treatment, which might improve the poor prognosis although exon 17 mutations may cause resistance to TKI [14]. We report a case of non-systemic mast cell sarcoma of the sternum with destructive growth in a 37-year-old man. He had a history of a yolk sac tumor 10 years earlier. The yolk sac tumor had been treated with chemotherapy before surgery, and in the resected mediastinal tumor, pathological examination failed to identify any viable tumor cells. Genetic testing of the mast cell tumor revealed a KIT exon 11 mutation (D579del). This was also found as a minor component in the antecedent yolk sac tumor, which has not previously been reported in these tumors.

An Outpatient-based Survey about the Recognition of Locomotive Syndrome and the Results of the Loco-check at a University Hospital in Tokyo

Background: To prevent locomotor dysfunction, the Japanese Orthopaedic Association (JOA) proposed the concept of locomotive syndrome (LS) in 2007, and has carried out many campaigns to increase the awareness of LS. Recently, the JOA reported that 26.6% of people recognized LS in internet based surveys. However, a survey of the recognition of LS using outpatient (hospital-based) cohorts has never been performed. Therefore, we surveyed the recognition of LS, the prevalence of LS and any correlations between LS and Original Research Article British Journal of Medicine & Medical Research, 4(17): 3255-3268, 2014 3256 the clinical data in the outpatient cohort. Methods: To investigate the recognition of LS and prevalence of LS, we conducted a questionnaire survey including the “loco-check” in 1010 (429 male and 581 female) orthopaedic outpatients at Juntendo University Hospital (Tokyo, Japan) from April to June 2013. Results: Only 24.6% of the patients knew about the concept of LS. In terms of the media sources from which the patients had received information about LS, 49.5% received LS information from TV. With regard to the prevalence of LS, 43.8% was classified into the LS group. The prevalence of LS was 32.9% in males and 51.8% in females. When the relationship between LS and orthopaedic disease was examined, 50 of 55 (90.9%) knee osteoarthritis (OA) patients, 21 of 26 (80.8%) hip OA patients and 98 of 151 (64.9%) lumbar spondylosis patients had statistically significant correlations with LS (p<0.0001). Conclusion: This study confirmed the rate of recognition of LS indicated by the JOA survey. Our studies also revealed that LS score was related to orthopaedic disorders. Our outpatient-based surveys may help provide a better understanding of the effects and trends of the campaigns to promote the recognition of LS.

Next-generation sequencing analysis for gastric adenocarcinoma with enteroblastic differentiation: emphasis on the relationship with hepatoid adenocarcinoma

Histologically tubulopapillary structures with glycogen-rich clear cytoplasm in gastric adenocarcinoma with enteroblastic differentiation (GAED) are well known, but a solid growth pattern can also be observed as a minor component. In contrast, hepatoid adenocarcinoma (HAC) of the stomach shows many overlapping features, including solid pattern and α-fetoprotein expression. In this study, we employed next-generation sequencing (NGS) to establish a molecular/clinicopathological concept of GAED and clarify whether these two tumors should be grouped together in one category. Among 2273 primary gastric cancers treated in our hospital between 2008 and 2017, we defined 51 cases as GAEDs showing tubulopapillary or solid patterns that express at least one of the following markers: α-fetoprotein, glypican-3, or spalt-like transcription factor 4. All cases previously diagnosed as HAC in our hospital had clear cytoplasm and were included as GAEDs by histological re-evaluation and immunohistochemical findings. We performed NGS for 24 histologically typical GAEDs and Sanger sequencing for the remaining cases. The most frequently mutated gene was TP53, and almost all cases with missense mutation showed p53 overexpression. An analysis of copy number variation revealed that ERBB2 amplification was the most frequent in GAED. Additionally, HER2 immunohistochemistry and fluorescence in situ hybridization confirmed that 22% of informative cases were HER2 positive. There was no correlation between molecular/clinicopathological parameters and α-fetoprotein expression or growth patterns in GAED. Our analysis showed that GAED frequently harbors TP53 mutations and ERBB2 amplification. As with conventional gastric adenocarcinoma, trastuzumab may be effective for GAED. Furthermore, HAC may be subcategorized as a solid-type GAED.

Pediatric soft tissue tumor of the upper arm with LMNA-NTRK1 fusion

A 6-year-old girl was admitted to our hospital because of the presence of a slow-growing tumor in her right elbow. Biopsy specimens showed a round to spindle cell neoplasm with uncertain malignant potential, leading to the decision of surgical resection. Histologically, the resected tumor was encapsulated by fibrous tissue but focally invaded the surrounding skeletal muscles. The tumor was composed of ganglion cell-like short spindle cells with lymphocytic infiltration in the collagenous background. Tumor cells with large bizarre nuclei were occasionally observed, and multinucleated giant cells were scattered at the periphery. Hemangiopericytoma-like patterns and adipose tissue elements were not evident, and mitotic figures were rarely observed (<1 per 10 high-power fields). Immunohistochemically, the tumor cells were positive for S-100 and CD34 and focally positive for epithelial membrane antigen and AE1/AE3. RNA sequencing and subsequent reverse-transcription polymerase chain reaction revealed alternative splicing forms of LMNA-NTRK1 fusion (Ex2-Ex10 and Ex2-Ex15).