The docking protein FRS2␣ is a major mediator of fibroblast growth factor (FGF) signaling. However, the physiological role of FRS2␣ in vivo remains unknown. In this report, we show that Frs2␣-null mouse embryos have a defect in anterior-posterior (A-P) axis formation and are developmentally retarded, resulting in embryonic lethality by embryonic day 8. We demonstrate that FRS2␣ is essential for the maintenance of self-renewing trophoblast stem (TS) cells in response to FGF4 in the extraembryonic ectoderm (ExE) that gives rise to tissues of the placenta. By analyzing chimeric embryos, we found that FRS2␣ also plays a role in cell movement through the primitive streak during gastrulation. In addition, experiments are presented demonstrating that Bmp4 expression in TS cells is controlled by mitogen-activated protein kinase-dependent FGF4 stimulation. Moreover, both the expression of Bmp4 in ExE and activation of Smad1/5 in epiblasts are reduced in Frs2␣-null embryos. These experiments underscore the critical role of FRS2␣ in mediating multiple processes during embryonic development and reveal a potential new link between FGF and Bmp4 signaling pathways in early embryogenesis.

Ewing's sarcoma (ES) is the second-most frequent pediatric bone tumor. Chromosomal translocation t(11;22)(q24:q12) results in the formation of EWS/FLI1 gene fusion, which is detected in approximately 90% of tumors of the Ewing family. Several transcriptome studies have provided lists of genes associated with EWS/FLI1 expression. However, the protein expression profiles associated with EWS/FLI1 have yet to be elucidated. In this study, to identify the regulated proteins associated with EWS/FLI1 and therapeutic targets in ES, we conducted proteomic studies using EWS/FLI1 knockdown in four Ewing's sarcoma cell lines and human mesenchymal stem cells (hMSCs) expressing EWS/FLI1. Isobaric tags for relative and absolute quantitation (i-TRAQ) analyses identified more than 2,000 proteins regulated by the EWS/FLI1 fusion. In addition, the network analyses identified several critical pathways, including XBP1, which was ranked the highest. XBP1 is a protein well known to play an important role in the unfolded protein response (UPR) to endoplasmic reticulum (ER) stress through the IRE1α-XBP1 pathway. We confirmed the high mRNA expression of XBP1 (spliced XBP1 and unspliced XBPl) in surgical samples and cell lines in ES. The silencing of XBP1 significantly suppressed the cell viabilities in ES cell lines. In the inhibitor assays using IRE1α-XBP1 inhibitors, including toyocamycin, we confirmed that these agents significantly suppressed the cell viabilities, leading to apoptosis in ES cells both in vitro and in vivo. Our findings suggested that IRE1α-XBP1 inhibitors might be useful for developing novel therapeutic strategies in ES.

Invasive mucinous adenocarcinoma (IMA) of the lung is a unique variant of lung adenocarcinoma.Aberrant mucin expression is associated with cancer development and metastasis. However, the clinicopathological significance of mucin expression in IMA is not fully understood. Herein, we evaluated the clinicopathological, immunohistochemical, and molecular characteristics of 70 IMA tumors. EGFR, KRAS, GNAS, and TP53 mutations were assessed by PCR-based sequencing.Next-generation sequencing was used to assess cases without EGFR/KRAS mutations. A NanoString-based screening for fusions was performed in all IMAs without mitogenic driver mutations. Expression of mucins (MUC1, MUC2, MUC4, MUC5AC, and MUC6) was evaluated by immunohistochemistry and categorized as follows: negative (<10% of tumor cells), patchy expression (<90% of tumor cells), or diffuse expression (≥90% of tumor cells).Immunohistochemical testing for transcription factors (TTF-1, CDX-2, HNF1β, HNF3α, HNF3β, and HNF4α) was also performed. As expected, KRAS mutations were the most common (in 67% of cases), followed by small numbers of other alterations. Patchy or diffuse expression of MUC1, MUC2, MUC4, MUC5AC, and MUC6 was observed in 52% or 6%, 3% or 0%, 30% or 3%, 26% or 73%, and 59% or 27% of cases, respectively. Furthermore, all IMAs were generally positive for HNF1β (100%), HNF3α (100%), HNF3β (100%), and HNF4α (99%) but were positive less often for TTF-1 (6%) and CDX2 (9%). Overall, there was no significant correlation between mucin expression and transcription factor expression. Unexpectedly, diffuse expression of MUC6 was significantly associated with KRAS-wild type tumors (p=0.0008), smaller tumor size (p=0.0073), and tumors in female patients (p=0.0359) in multivariate analyses. Furthermore, patients with tumors exhibiting diffuse MUC6 expression had significantly favorable outcomes. Notably, none of these patients died of the disease. Our data suggested that diffuse expression of MUC6 defines a distinct clinicopathological subset of IMA characterized by wild-type KRAS and possibly less aggressive clinical course.

Purpose: Giant cell tumor of bone (GCTB) is a local aggressive bone tumor, histologically classified as intermediate malignancy. Recently, the RANKL inhibitor, denosumab, was developed as a novel and effective treatment option for GCTB. Since the risk of preoperative use of denosumab with curettage had been previously reported, this study aimed to investigate the relationship between recurrences and clinicopathological features associated with adjuvant denosumab treatment in GCTB. Methods: A total of 87 GCTB cases were treated at our institution. We reviewed 66 patients with conventional-type GCTB occurring in the extremities and analyzed 78 surgical treatments, including curettages and resections, with clinicopathological features and denosumab treatment. Results: GCTB lesions, including 66 primary and 12 recurring, underwent surgical treatment like curettage and resection. Recurrence-free survivals in 78 GCTB surgeries were 78.7% in 3 years and 71.9% in 5 years. In the resected cases of GCTBs, there was no recurrence either with or without denosumab. In curettage cases, 3-year recurrence-free survivals were 0.0% ( n = 3) in preoperative treatment of denosumab, 66.7% ( n = 6) in postoperative treatment, and 76.6% ( n = 43) in no treatment. Interestingly, three preoperative treatment cases demonstrated low MIB-1 index despite 100% recurrence. The other clinicopathological factors did not contribute much to the risk of recurrence in curettage cases. Conclusion: Our findings revealed the use of denosumab in GCTB, prior to curettage, to possibly increase the risk of local recurrence. Together with previous reports, our finding might provide information for beneficial treatment of GCTB.

Background Soft tissue sarcomas are a heterogeneous group of rare malignant tumors. Advanced soft tissue sarcomas have a poor prognosis, and effective systemic therapies have not been established. Tyrosine kinases are increasingly being used as therapeutic targets for a variety of cancers and soft tissue sarcomas. Although complex karyotype sarcomas typically tend to carry more potentially actionable genetic alterations than do translocation-associated sarcomas (fusion gene sarcomas), based on our database review, we found that leiomyosarcoma and malignant peripheral nerve sheath tumors have lower frequencies of potential targets than other nontranslocation soft tissue sarcomas. We theorized that both leiomyosarcoma and malignant peripheral nerve sheath tumors might be included in any unique translocations. Furthermore, if tyrosine kinase imbalances, especially fusion genes, occur in patients with leiomyosarcomas and malignant peripheral nerve sheath tumors, tyrosine kinase inhibitors might be a drug development target for this sarcoma. In this study, we used a tyrosine kinase screening system that could detect an imbalance in mRNA between 5’- and 3’-sides in tyrosine kinase genes to identify potential novel therapeutic tyrosine kinase targets for soft tissue sarcomas. Questions/purposes (1) Are there novel therapeutic tyrosine kinase targets in tumors from patients with soft tissue sarcomas that are detectable using mRNA screening focusing on imbalance expressions between the 5’ and 3’ end of the kinase domain? (2) Can potential targets be verified by RNA sequencing and reverse transcription PCR (RT-PCR)? (3) Will potential fusion gene(s) transform cells in in vitro assays? (4) Will tumors in mice that have an identified fusion gene respond to treatment with a therapeutic drug directed at that target? Methods We used mRNA screening to look for novel tyrosine kinase targets that might be of therapeutic potential. Using functional assays, we verified whether the identified fusion genes would be good therapeutic candidates for soft tissue sarcomas. Additionally, using in vivo assays, we assessed whether suppressing the fusion’s kinase activity has therapeutic potential. Study eligibility was based on a patient having high-grade spindle cell and nontranslocation sarcomas, including leiomyosarcoma, malignant peripheral nerve sheath tumor, and high-grade myxofibrosarcoma. Between 2015 and 2019, of the 172 patients with soft tissue sarcomas treated with surgical resection at Juntendo University Hospital, 72 patients had high-grade nontranslocation sarcomas. The analysis was primarily for leiomyosarcoma and malignant peripheral nerve sheath tumors, and there was a limitation of analysis size (reagent limitations) totaling 24 samples at the start of the study. We collected additional samples from a sample bank at the Tokyo Medical and Dental University to increase the number of sarcomas to study. Therefore, in this study, a total of 15 leiomyosarcoma samples, five malignant peripheral nerve sheath tumors samples, and four high-grade myxofibrosarcoma samples were collected to achieve the sample size of 24 patients. To identify tyrosine kinase fusion genes, we designed a NanoString-based assay (NanoString Technologies Inc, Seattle, WA, USA) to query the expression balances regarding transcripts of 90 tyrosine kinases at two points: the 5’ end of the kinase domain and within the kinase domain or 3’ end of the kinase domain. The tumor’s RNA was hybridized to the NanoString probes and analyzed for the expression ratios of outliers from the 3’ to 5’ end of the kinase domain. Presumed novel fusion events in these positive tumors that were defined by NanoString-based assays were confirmed tyrosine kinase fusion genes by RNA sequencing and confirmatory RT-PCR. Functional analyses consisting of in vitro and in vivo assays were also performed to elucidate whether the identified tyrosine kinase gene fusions were associated with oncogenic abilities and drug responses. Results We identified aberrant expression ratios regarding the 3’ to 5’ end of the kinase domain ratios in ROS1 transcripts in a leiomyosarcoma in a 90-year-old woman. A novel MAN1A1-ROS1 fusion gene was identified from her thigh tumor through RNA sequencing, which was confirmed with real-time PCR. In functional assays, MAN1A1-ROS1 rearrangement revealed strong transforming potential in 3T3 cells. Moreover, in an in vivo assay, crizotinib, a ROS1 inhibitor, markedly inhibited the growth of MAN1A1-ROS1 rearrangement-induced transformed cells in a dose-dependent manner. Conclusion We conducted tyrosine kinase screening to identify new therapeutic targets in soft tissue sarcomas. We found a novel MAN1A1-ROS1 fusion gene that may be a therapeutic target in patients with leiomyosarcoma. This study demonstrates that the mRNA screening system may aid in the development of useful therapeutic options for soft tissue sarcomas. Clinical Relevance If novel tyrosine fusions such as MAN1A1-ROS1 fusion can be found in sarcomas from other patients, they could offer avenues for new molecular target therapies for sarcomas that currently do not have effective chemotherapeutic options. Therefore, the establishment of a screening system that includes both genomic and transcript analyses in the clinical setting is needed to verify our discoveries and take the developmental process of treatment to the next step.

NTRK fusion-positive tumors are known to be highly sensitive to TRK inhibitors, such as larotrectinib and entrectinib. Therefore, identification of patients who can potentially benefit from these inhibitors is important; however, the frequency of NTRK fusions in Japanese patients with colorectal cancer (CRC) is unknown. We performed pan-TRK staining using TMA-based immunohistochemistry (IHC) on samples from 971 consecutive Japanese CRC cases from a single institution. Positive cases were further analyzed using NanoString and subsequent targeted RNA sequencing. We found three positive cases using TRK-IHC. Furthermore, the Nanostring assay supported the presence of NTRK fusion in these cases. Subsequent targeted RNA-sequencing and RT-PCR revealed two cases with TPM3-NTRK1 and one with TPR-NTRK1. The TNM stages of these cases were stage I, stage IIA, and stage IIIB, and two showed microsatellite instability-high status. Next-generation sequencing analysis using Cancer hotspot panel revealed TP53 and SMAD4 mutations in separate cases. IHC of β-catenin did not show nuclear accumulation. We found three cases (0.31%) of CRC with NTRK1 fusion among 971 consecutive Japanese CRC cases. No potential driver alterations other than NTRK fusion were identified in these three patients.

Background Soft-tissue sarcomas are a rare group of malignant tumors that usually are treated with surgical excision and radiation therapy, but recently, pazopanib, an oral tyrosine kinase inhibitor, has been used in patients with metastases who do not respond to standard chemotherapy regimens. Based on patients with advanced soft-tissue sarcomas who had received prior chemotherapy, several clinical studies have reported the survival and sensitivity (approximately 5% to 10% sensitive) of patients with soft-tissue sarcomas treated with pazopanib. Recently, next-generation sequencing (NGS) technologies have been used to provide a wide genetic information and to develop personalized medicine in cancer treatment. However, there are few reports and no genetic analyses of patients with soft-tissue sarcomas who had a complete response (CR) to pazopanib. Questions/purposes We described the clinicopathologic features of a patient with a rare, advanced soft-tissue sarcoma who achieved a CR to pazopanib treatment. Furthermore, integrative analyses using NGS and arrays were performed to elucidate characteristic alterations, including gene mutations, copy number changes, and protein expression that were associated with response to pazopanib. Additionally, functional analyses consisting of in vitro and in vivo assays were also performed to elucidate whether the identified alterations were associated with oncogenic abilities and drug responses. Methods In a sample from a 70-year-old woman with an advanced soft-tissue sarcoma treated for 1 month with 800 mg of oral pazopanib daily, CT scans demonstrated a CR to treatment. To our knowledge, there have been no patients with soft-tissue sarcomas among several clinical trials of pazopanib that have achieved a CR and therefore, our patient is considered to be extremely rare. We performed an integrative analysis including whole-exome sequencing, transcriptome sequencing, and phosphorylation profiling of receptor tyrosine kinases (RTK) using tumor samples from a patient with a CR matched to normal samples. From here on we will refer to this patient as having a CR, although a short term high-grade partial response may be more accurate. These analyses were performed using NGS and the phosphoreceptor tyrosine kinase (phospho-RTK) array. As a validation study, we also performed target sequencing using three samples from patients with long-term stable disease and two samples from patients with progressive disease who responded to pazopanib treatment. In addition, characteristic gene alterations that were identified according to the response to pazopanib in one patient with a CR, in three patients with long-term stable disease, and in 27 patients with high-grade soft-tissue sarcomas with different histologic subtypes and different responses to pazopanib were verified by quantitative real-time polymerase chain reaction. We conducted a focus formation assay to evaluate the transforming activities of these genomic alterations. Results In the patient with a CR to pazopanib, we identified several somatic mutations including Fms related receptor tyrosine kinase 1 (FLT1) p.G38S, platelet-derived growth factor receptor alpha (PDGFRA) p.T83S, and platelet-derived growth factor receptor beta (PDGFRB) exon 13 skipping. Amplification at chromosome 12q13-14 encompassing GLI family zinc finger 1 (GLI1) and cyclin-dependent kinase-4 (CDK4) was also detected. Furthermore, an elevated PDGFRB phosphorylation level was observed in the tumor. In target sequencing analyses in five patients, one of three patients with long-term stable disease had 12q13-14 amplification. The mRNA expression of GLI1, CDK4, and pazopanib targets including PDGFRA, PDGFRB, vascular endothelial growth factor receptor (VEGFR)1-3, and stem cell factor receptor (KIT) in samples from the patient with a CR, and 27 patients with high-grade soft-tissue sarcomas was verified. The expression of GLI1 was characteristically increased in the patient with a CR and in those with long-term stable disease relative to other patients with soft-tissue sarcomas. Overexpression of GLI1 showed strong transforming potential in 3T3 cells. Moreover, the overexpression of GLI1 upregulated the expression of the PDGFRB protein and promoted phosphorylation, which was dose-dependently inhibited by pazopanib. However, inhibition of GLI1-induced transformation by pazopanib was limited in the focus formation assay; therefore, mechanisms other than PDGFRB activation may contribute to transformation. Conclusions We identified several gene alterations that might be associated with a CR and long-term stable disease in patients who received pazopanib for advanced soft-tissue sarcomas. We therefore believe that this distinct molecular profile warrants further investigation to identify predictive biomarkers of the response to pazopanib. Clinical Relevance Our findings identify molecular mechanisms that possibly explain the high sensitivity of soft-tissue sarcomas to pazopanib and may lead to the development of predictive biomarkers and novel therapies in patients with this and other types of soft-tissue sarcomas.

Gene expression imbalances were measured for tyrosine kinase (TK) genes using Nanostring in 19 samples of inflammatory myofibroblastic tumor (IMT). All cases were immunohistochemically stained with anaplastic lymphoma kinase (ALK) and pan-tropomyosin-related-kinase (pan-Trk) antibodies. Five cases with imbalanced ALK expression, reported with Nanostring, were tested using fluorescence in situ hybridization (FISH); two cases with imbalanced neurotrophic tyrosine receptor kinase 3 (NTRK3) expression were tested using reverse transcription-polymerase chain reaction (RT-PCR). One case with imbalanced expression for ROS proto-oncogene 1 (ROS1) was tested using RNA sequencing and RT-PCR. TK fusions were detected in all cases with imbalanced TK expression. RNA sequencing detected a FN1–ROS1 fusion gene in an adult IMT case. IMT with ALK rearrangement showed myofibroblast-dominant features. IMT with ETV6–NTRK3 fusion showed prominent lymphoplasmacytic infiltration with scattered myofibroblasts. Pan-Trk IHC revealed only scattered positively stained cells in IMT with ETV6–NTRK3 fusion gene. ROS1-positive IMT showed myofibroblast-dominant features.