Identification of genes regulated by the EWS/NR4A3 fusion protein in extraskeletal myxoid chondrosarcoma

NR4A3 Fluorescence In Situ Hybridization Analysis in Cytologic and Surgical Specimens of acinic cell carcinoma

BACKGROUND

Acinic cell carcinoma (AciCC) may pose a diagnostic challenge, particularly on small biopsies and fine needle aspiration (FNA) because of its variable histology including potential high grade transformation and its mimickers. Immunoreactivity with circumferential membranous staining for DOG1 can support the diagnosis of AciCC but is not entirely specific. A novel rearrangement t(4;9)(q13;q31) leading to upregulation of nuclear receptor subfamily 4 group A member 3 (NR4A3) has been described in AciCC, is potentially detectable by Fluorescence in situ hybridization (FISH) and may be useful in the evaluation for AciCC.

METHODS

Using NR4A3 Dual Color Break Apart Probe (Zytovision, Germany) FISH was performed on AciCCs from three large academic institutions. NR4A3 rearrangement was defined as positive signal patterns in 15% of tissue interphase nuclei.

RESULTS

52 AciCCs including 47 resections and 5 FNAs (including 5 paired FNA/resections) were analyzed. 5 non-AciCC salivary gland tumors and 2 sialadenitis cases were used as controls. 8 (15%) (8/52) AciCCs failed FISH testing. FISH was positive in 23 AciCCs (sensitivity 59%, 23/39) with 100% concordance between five matched resection/FNAs (three were positive for FISH and two were negative). FISH was negative in all non-AciCCs (specificity: 100%, 0/7).

CONCLUSION

NR4A3 FISH has a sensitivity of 59% and specificity of 100% in detecting AciCC which suggests that NR4A3 rearrangement-driven upregulation is a recurrent, specific oncogenic event in AciCC, consistent with prior results. 100% concordance between matched FNA/resection samples validate its potential utility on cytology samples.

Extraskeletal Myxoid Chondrosarcoma: State of the Art and Current Research on Biology and Clinical Management

Simple Summary

The aim of this review is to provide an overview of the biological basis of pathogenesis and current research in extraskeletal myxoid chondrosarcoma (EMC), together with the state of the art of treatment for localized and advanced disease. EMC is an ultra-rare sarcoma sub-type, more often arising from the soft tissues, marked by specific molecular features consisting in rearrangement of the NR4A3 gene, identified in recent years and very useful to distinguish EMC from other mimics. Available pharmacological treatments in particular are discussed, with a focus on the most recent results and future perspectives.

Abstract

Extraskeletal myxoid chondrosarcoma (EMC) is an ultra-rare mesenchymal neoplasm with uncertain differentiation, which arises mostly in the deep soft tissue of proximal extremities and limb girdles. EMC is marked by a translocation involving the NR4A3 gene, which can be fused in-frame with different partners, most often EWSR1 or TAF1. Although EMC biology is still poorly defined, recent studies have started shedding light on the specific contribution of NR4A3 chimeric proteins to EMC pathogenesis and clinical outcome. Standard treatment for localized disease is surgery, plus or minus radiation therapy with an expected prolonged survival even though the risk of relapse is about 50%. In advanced cases, besides the standard chemotherapy currently used for soft tissue sarcoma, antiangiogenic agents have recently shown promising activity. The aim of this review is to provide the state of the art of treatment for localized and advanced disease, with a focus on pharmacological treatments available for EMC. The biological basis of current research and future perspectives will be also discussed.

Extraskeletal Myxoid Chondrosarcomas: Combined Modality Therapy With Both Radiation and Surgery Improves Local Control

OBJECTIVE

We evaluated our experience treating patients with localized extraskeletal myxoid chondrosarcomas (EMCs) to evaluate outcomes and relapse rates in order to better inform treatment decisions for these rare soft tissue sarcomas.

MATERIALS AND METHODS

We reviewed the records of 41 consecutive patients with localized EMC treated at our institution from 1990 to 2016. Most patients (n=33, 80%) received combined modality therapy with surgery and radiation therapy, whereas only 8 (20%) underwent surgery alone. The Kaplan-Meier method was used to estimate rates of overall survival, disease-specific survival, local control (LC), and distant metastatic-free survival (DMFS).

RESULTS

Median follow-up time was 94 months (range, 8 to 316). The 10-year LC, DMFS, disease-specific survival, and overall survival rates were 90%, 69%, 85%, and 66%, respectively. There were 5 patients (12%) with local relapse at a median time of 75 months (range, 13 to 176). On univariate analysis, the only significant factor associated with poorer LC was the use of surgery alone (10 y LC, 63% vs. 100% for combined modality therapy, P=0.004), which remained the only factor also significant on the multivariable analysis (P=0.02; hazard ratio [HR], 12.7; 95% confidence interval [CI], 1.4-115.3). In total, 13 patients (32%) developed distant metastatic at a median time of 28 months (range, 3 to 154). Interestingly, local recurrence was the only factor associated with poorer DMFS on multivariate analysis (P=0.04; HR, 3.9; 95% CI, 1.1-14.7).

CONCLUSIONS

For patients with EMC, surgery alone was associated with a higher risk of local recurrence. Therefore, we recommend optimal local therapeutic strategies upfront with both surgery and radiation therapy to reduce the risk of local and ultimately distant recurrence.

INSM1 expression and its diagnostic significance in extraskeletal myxoid chondrosarcoma

Extraskeletal myxoid chondrosarcoma is a rare subtype of sarcoma that affects the soft tissue and bones in middle-aged and elderly adults. Its diagnosis can be challenging, with the differential diagnoses including a wide variety of mesenchymal tumors. The line of differentiation of extraskeletal myxoid chondrosarcoma has been controversial, but recent evidence suggests a neuroendocrine phenotype. INSM1 is a zinc-finger transcription factor that plays a pivotal role in neuroendocrine differentiation, and has been proposed as a promising immunohistochemical marker of neuroendocrine carcinoma. The aim of this study was to determine the prevalence of INSM1 expression in extraskeletal myxoid chondrosarcoma and to understand its significance in sarcoma diagnosis. We immunostained the representative sections of 31 NR4A3-rearranged extraskeletal myxoid chondrosarcomas and 187 histological mimics. Nuclear staining of moderate or higher intensity in at least 5% of tumor cells was considered positive. Twenty-eight of the 31 extraskeletal myxoid chondrosarcomas (90%) were positive for INSM1, providing strong evidence for neuroendocrine differentiation. The staining was diffuse (>50%) in 17 cases, with most immunopositive tumors showing at least focal strong expression. The INSM1 staining extent was not correlated with cytomorphology, synaptophysin expression, or fusion types (EWSR1 vs non-EWSR1). In contrast, INSM1 expression was negative in 94% of the 187 other mesenchymal tumors. INSM1-positive mimics comprised a small subset of chordoma (1 of 10), soft tissue myoepithelioma (1 of 20), ossifying fibromyxoid tumor (3 of 10), and Ewing sarcoma (3 of 10), among other tumor types. The majority of these cases showed labeling in <25% of the tumor cells. Although not entirely sensitive or specific, INSM1 could be a potential marker for the diagnosis of extraskeletal myxoid chondrosarcoma when molecular genetic access is limited.

EWSR1 regulates mitosis by dynamically influencing microtubule acetylation

EWSR1, participating in transcription and splicing, has been identified as a translocation partner for various transcription factors, resulting in translocation, which in turn plays crucial roles in tumorigenesis. Recent studies have investigated the role of EWSR1 in mitosis. However, the effect of EWSR1 on mitosis is poorly understood. Here, we observed that depletion of EWSR1 resulted in cell cycle arrest in the mitotic phase, mainly due to an increase in the time from nuclear envelope breakdown to metaphase, resulting in a high percentage of unaligned chromosomes and multipolar spindles. We also demonstrated that EWSR1 is a spindle-associated protein that interacts with α-tubulin during mitosis. EWSR1 depletion increased the cold-sensitivity of spindle microtubules, and decreased the rate of spindle assembly. EWSR1 regulated the level of microtubule acetylation in the mitotic spindle; microtubule acetylation was rescued in EWSR1-depleted mitotic cells following suppression of HDAC6 activity by its specific inhibitor or siRNA treatment. In summary, these results suggest that EWSR1 regulates the acetylation of microtubules in a cell cycle-dependent manner through its dynamic location on spindle MTs, and may be a novel regulator for mitosis progress independent of its translocation.

The interplay of NR4A receptors and the oncogene-tumor suppressor networks in cancer

Nuclear receptor (NR) subfamily 4 group A (NR4A) is a family of three highly homologous orphan nuclear receptors that have multiple physiological and pathological roles, including some in cancer. These NRs are reportedly dysregulated in multiple cancer types, with many studies demonstrating pro-oncogenic roles for NR4A1 (Nur77) and NR4A2 (Nurr1). Additionally, NR4A1 and NR4A3 (Nor-1) are described as tumor suppressors in leukemia. The dysregulation and functions of the NR4A members are due to many factors, including transcriptional regulation, protein-protein interactions, and post-translational modifications. These various levels of intracellular regulation result from the signaling cross-talk of the NR4A members with various signaling pathways, many of which are relevant to cancer and likely explain the family members' functions in oncogenesis and tumor suppression. In this review, we discuss the multiple functions of the NR4A receptors in cancer and summarize a growing body of scientific literature that describes the interconnectedness of the NR4A receptors with various oncogene and tumor suppressor pathways.

NF-κB target microRNAs and their target genes in TNFα-stimulated HeLa cells

As a transcription factor, NF-κB was demonstrated to regulate the expressions of miRNAs. However, only a few miRNAs have been identified as its targets so far. In this study, by using ChIP-Seq, Genechip and miRNA-Seq techniques, we identified 14 NF-κB target miRNAs in TNFα-stimulated HeLa Cells, including miR-1276, miR-1286, miR-125b-1-3p, miR-219-1-3p, miR-2467-5p, miR-3200-3p, miR-449c-5p, miR-502-5p, miR-548d-5p, miR-30b-3p, miR-3620-5p, miR-340-3p, miR-4454 and miR-4485. Of these miRNAs, 8 detected miRNAs were also NF-κB target misRNAs in TNFα-stimulated HepG2 cells. We also identified 16 target genes of 6 miRNAs including miR-125b-1-3p, miR-1286, miR-502-5p, miR-1276, miR-219-1-3p and miR-30b-3p, in TNFα-stimulated HeLa cells. Target genes of miR-125b-1-3p and miR-1276 were validated in HeLa and HepG2 cells by transfecting their expression plasmids and mimics. Bioinformatic analysis revealed that two potential target genes of miR-1276, BMP2 and CASP9, were enriched in disease phenotypes. The former is enriched in osteoarthritis, and the latter is enriched in Type 2 diabetes and lung cancer, respectively. These findings suggested that this little known miRNA might play roles in these diseases via its two target genes of BMP2 and CASP9. The expression of miR-125b-1 regulated by NF-κB has been reported in diverse cell types under various stimuli, this study found that its expression was also significantly regulated by NF-κB in TNFα-stimulated HeLa and HepG2 cells. Therefore, this miRNA was proposed as a central mediator of NF-κB pathway. These findings provide new insights into the functions of NF-κB in its target miRNA-related biological processes and the mechanisms underlying the regulation of these miRNAs.

The orphan nuclear receptors at their 25-year reunion

The nuclear receptor superfamily includes many receptors, identified based on their similarity to steroid hormone receptors but without a known ligand. The study of how these receptors are diversely regulated to interact with genomic regions to control a plethora of biological processes has provided critical insight into development, physiology, and the molecular pathology of disease. Here we provide a compendium of these so-called orphan receptors and focus on what has been learned about their modes of action, physiological functions, and therapeutic promise.