Sclerosing Epithelioid Fibrosarcoma.

Sclerosing epithelioid fibrosarcoma (SEF) is a distinctive sarcoma that may arise in nearly any soft tissue site or bone. While there has been past controversy as to whether it is related to low-grade fibromyxoid sarcoma (LGFMS), it has been shown to behave far more aggressively than LGFMS. SEF has a propensity to metastasize to the lungs and bone and arise within the abdominal cavity. Histologically, it is characterized by uniform nuclei embedded in a densely collagenous stroma simulating osteoid. By immunohistochemistry, it is often strongly positive for MUC4. The majority (75%) have EWSR1 gene rearrangement, most commonly with CREB3L1 as a fusion partner, although a variety of FUS/EWSR1 and CREB3L1/CREB3L2/CREB3L3 fusions have been described in addition to others. SEF is currently recalcitrant to nearly all chemotherapy and radiation therapy.

Low-grade Fibromyxoid Sarcoma With Massive Degeneration: A Case of Unusual Gross and Histological Features.

BACKGROUND: Low-grade fibromyxoid sarcoma (LGFMS) is a rare type of sarcoma which is observed in the soft tissue of proximal extremities, typically in young and middle-aged adults. It consists of a solid proliferation of bland spindle cells within collagenous and myxoid stroma. CASE REPORT: Herein, we report a case of LGFMS with massive degeneration and hyalinization. A 30-year-old man presented with a well-circumscribed mass measuring 15 cm in diameter in his left biceps femoris muscle. Marginal tumor resection was performed under the clinical diagnosis of an ancient schwannoma or chronic expanding hematoma (CEH). The resected tissue revealed a well-demarcated tumor mass with massive degeneration and hyalinization with focal calcification. Proliferation of spindle tumor cells with abundant collagenous stroma, which resembled the fibrous capsule of CEH, was observed exclusively in a small area of the periphery of the tumor. No nuclear palisading, myxoid stroma, or collagen rosettes were identified. Immunohistochemical analysis demonstrated that the spindle tumor cells expressed mucin 4 and epithelial membrane antigen. Reverse transcriptase-polymerase chain reaction analysis detected mRNA expression of fused in sarcoma::CAMP-responsive element binding protein 3-like protein 2 (FUS::CREB3L2) fusion gene. Thus, a final diagnosis of LGFMS with massive degeneration and FUS::CREB3L2 fusion was made. CONCLUSION: The recognition of massive degeneration and hyalinization as unusual features of LGFMS might be helpful to differentiate it from CEH and other benign spindle-cell tumors.

Case report: Primary pleural low-grade fibromyxoid sarcoma in a 4-year-old boy with molecular confirmation.

Low-grade fibromyxoid sarcoma (LGFMS) is a rare malignant fibroblastic tumor, principally affecting the deep tissues of the proximal trunk and extremities in young adults. However, primary pleural LGFMS is extremely rare, and only three cases have been reported in the previous English literature without genetic confirmation. Furthermore, the historical pleural LGFMS cases were all adults, and the primary pleural LGFMS in children has never been reported to date. Here, we presented a primary pleural LGFMS in a 4-year-old boy with detailed clinical, pathological, and molecular results. Histologically, the current tumor showed typical alternating collagenous and myxoid areas, containing spindled or oval tumor cells arranged in a whorled and short fascicular pattern. In some areas, the tumor cells exhibited moderate atypia, and mitotic figures were identified but without the identification of giant collagen rosettes. Immunohistochemically, all the neoplastic cells showed strong and diffuse positivity for MUC4. Genetically, FUS gene rearrangement was revealed by fluorescence in-situ hybridization (FISH), and subsequently, next-generation sequencing (NGS) and polymerase chain reaction (PCR) further demonstrated the FUS::CREB3L2 fusion transcript. To the best of our knowledge, this is the first case of primary pleural LGFMS with the identification of FUS gene rearrangement and FUS::CREB3L2 fusion in a 4-year-old child. Our study expands the age range of pleural LGFMS and highlights the combination of morphological, immunohistochemical, and molecular analyses in such challenging cases.

Comprehensive next-generation sequencing reveals low-grade fibromyxoid sarcoma of the vulva missed by morphological diagnosis: a case report.

Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue tumor composed of bland spindled cells in a variably fibrous to myxoid stroma. Its occurrence in the vulva region is rare, and thus, it may not be always taken into account in the differential diagnosis. Here, we describe a 34-year-old woman presented with a right vulvar mass and underwent complete surgical excision. The final pathologic diagnosis revealed LGFMS of the vulva based on the morphological, immunophenotypic, and molecular genetic features. The patient has not experienced a local or metastatic recurrence after 9-month follow-up. Despite being rare, LGFMS of the vulva should be considered when making a diagnosis of vulvar lesions. We also report that the genetic testing by next-generation sequencing (NGS) represents a very useful tool for the differential diagnosis of LGFMS from its mimics. Moreover, we have reviewed the literature on LGFMS of the vulva and summarized the characteristics of the patients, providing assistance for the diagnosis of such patients. Most vulvovaginal LGFMS can be fully removed through surgery. However, ongoing monitoring over the long term is essential as local and/or distant spread can occur decades after the initial diagnosis.

A systemic cell stress signal confers neuronal resilience toward oxidative stress in a Hedgehog-dependent manner.

Cells possess several conserved adaptive mechanisms to respond to stress. Stress signaling is initiated to reestablish cellular homeostasis, but its effects on the tissue or systemic levels are far less understood. We report that the secreted luminal domain of the endoplasmic reticulum (ER) stress transducer CREB3L2 (which we name TAILS [transmissible activator of increased cell livability under stress]) is an endogenous, cell non-autonomous activator of neuronal resilience. In response to oxidative insults, neurons secrete TAILS, which potentiates hedgehog signaling through direct interaction with Sonic hedgehog (SHH) and its receptor PTCH1, leading to improved antioxidant signaling and mitochondrial function in neighboring neurons. In an in vivo model of ischemic brain injury, administration of TAILS enables survival of CNS neurons and fully preserves cognitive function in behavioral tests. Our findings reveal an SHH-mediated, cell non-autonomous branch of cellular stress signaling that confers resilience to oxidative stress in the mature brain, providing protection from ischemic neurodegeneration.

Expression analysis and functional characterization of thioredoxin domain-containing protein 11.

BACKGROUNDS: The endoplasmic reticulum (ER) is a crucial organelle that regulates both the folding, modification and transport of many proteins and senses certain stimuli inside and outside of cells. ER-associated degradation (ERAD), including SEL1L is a crucial mechanism to maintain homeostasis. In this study, we performed comparative proteome analysis in wild-type (wt) and SEL1L-deficient cells. METHODS AND RESULTS: We found constitutively high expression of thioredoxin domain-containing protein 11 (TXNDC11) mRNA and protein in our SEL1L-deficient HEK293 cells by RT-PCR and Western blot analysis. The TXNDC11 gene possesses a well-conserved unfolded protein response element (UPRE) around its transcription start site, and ER stress increased TXNDC11 mRNA and luciferase reporter activity via this putative UPRE in HEK293 cells. The amounts of TXNDC11 protein in wild-type and SEL1L-deficient cells with or without thapsigargin (Tg) treatment were parallel to their mRNAs in these cells, which was almost proportional to spliced XBP1 (sXBP1) mRNA expression. The establishment and characterization of TXNDC11-deficient HEK293 cells revealed that the expression of three different ER resident stress sensors, ATF6α, CREB3 and CREB3L2, is regulated by TXNDC11. The rate of disappearance of the three proteins by CHX treatment in wt cells was remarkably different, and the full-length CREB3L2 protein was almost completely degraded within 15 min after CHX treatment. TXNDC11 deficiency increased the expression of each full-length form under resting conditions and delayed their disappearance by CHX treatment. Interestingly, the degree of increase in full-length CREB3/CREB3L2 by TXNDC11 deficiency was apparently higher than that in full-length ATF6α. The increase in these proteins by TXNDC11 deficiency was hardly correlated with the expression of each mRNA. Treatment with ER stress inducers influenced each full-length mature form, and the difference in each full-length form observed in wt and TXNDC11-deficient cells was smaller. CONCLUSION: This study demonstrated that TXNDC11 is an ER stress-inducible gene regulated by the IRE1-sXBP1 pathway. In addition, TXNDC11 is involved in the regulation of ATF6α, CREB3 and CREB3L2 protein expression, although the contribution to the stability of these proteins is quite variable. Therefore, its further characterization will provide new insights for understanding protein homeostasis in ER physiology and pathology.

CREB3L2 Modulates Nerve Growth Factor-Induced Cell Differentiation.

Nerve growth factor (NGF) stimulates numerous cellular physiological processes, including growth, differentiation, and survival, and maintains the phenotype of several neuronal types. Most of these NGF-induced processes require adaptation of the secretory pathway since they involve extensive remodeling of membranes and protein redistribution along newly formed neuritic processes. CREB3 transcription factors have emerged as signaling hubs for the regulation of numerous genes involved in the secretory pathway and Golgi homeostasis, integrating stimuli from multiple sources to control secretion, posttranslational modifications and trafficking of proteins. Although recent studies have focused on their role in the central nervous system, little is known about their participation in cell differentiation. Therefore, we aimed to analyze the expression and signaling mechanism of CREB3 transcription factor family members, using the NGF-induced PC12 cell differentiation model. Results show that NGF treatment causes Golgi enlargement and a parallel increased expression of proteins and mRNAs encoding for proteins required for membrane transport (transport factors). Additionally, a significant increase in CREB3L2 protein and mRNA levels is detected in response to NGF. Both MAPK and cAMP signaling pathways are required for this response. Interestingly, CREB3L2 overexpression hampers the NGF-induced neurite outgrowth while its inhibition enhances the morphological changes driven by NGF. In agreement, CREB3L2 overexpressing cells display higher immunofluorescence intensity of Rab5 GTPase (a negative regulator of PC12 differentiation) than control cells. Also, Rab5 immunofluorescence levels decrease in CREB3L2-depleted cells. Taken together, our findings imply that CREB3L2 is an important downstream effector of NGF-activated pathways, leading to neuronal differentiation.

Comparative Analysis of CREB3 and CREB3L2 Protein Expression in HEK293 Cells.

We performed a comparative analysis of two ER-resident CREB3 family proteins, CREB3 and CREB3L2, in HEK293 cells using pharmacological and genome editing approaches and identified several differences between the two. Treatment with brefeldin A (BFA) and monensin induced the cleavage of full-length CREB3 and CREB3L2; however, the level of the full-length CREB3 protein, but not CREB3L2 protein, was not noticeably reduced by the monensin treatment. On the other hand, treatment with tunicamycin (Tm) shifted the molecular weight of the full-length CREB3L2 protein downward but abolished CREB3 protein expression. Thapsigargin (Tg) significantly increased the expression of only full-length CREB3L2 protein concomitant with a slight increase in the level of its cleaved form. Treatment with cycloheximide and MG132 revealed that both endogenous CREB3 and CREB3L2 are proteasome substrates. In addition, kifunensine, an α-mannosidase inhibitor, significantly increased the levels of both full-length forms. Consistent with these findings, cells lacking SEL1L, a crucial ER-associated protein degradation (ERAD) component, showed increased expression of both full-length CREB3 and CREB3L2; however, cycloheximide treatment downregulated full-length CREB3L2 protein expression more rapidly in SEL1L-deficient cells than the full-length CREB3 protein. Finally, we investigated the induction of the expression of several CREB3 and CREB3L2 target genes by Tg and BFA treatments and SEL1L deficiency. In conclusion, this study suggests that both endogenous full-length CREB3 and CREB3L2 are substrates for ER-associated protein degradation but are partially regulated by distinct mechanisms, each of which contributes to unique cellular responses that are distinct from canonical ER signals.

MicroRNA-92b-3p promotes the progression of liver fibrosis by targeting CREB3L2 through the JAK/STAT signaling pathway.

Liver fibrosis is a common feature of almost all chronic liver diseases, which eventually leads to cirrhosis and even hepatocellular carcinoma (HCC). The current study showed that miR-92b plays an important role in the progression of HCC but its role in liver fibrosis is still unclear. Here we aimed to explore the role and underlying molecular mechanism of miR-92b-3p in the activated hepatic stellate cells (HSCs) and the pathological process of hepatic fibrosis. We found that miR-92b-3p was highly expressed both in fibrotic liver tissues from patients and model mice and in activated LX-2 cells stimulated with TGF-ß1. However, the expression of miR-92b-3p was downregulated in inactivated LX-2 cells treated with adipogenic differentiation mixture (MDI). In addition, we found that miR-92b-3p mimic could promote the activation, proliferation, and migration of LX-2 and HSC-T6 cells, while miR-92b-3p inhibitor could reverse this process. From the TargetScan databases, we found that CREB3L2 is a potential target of miR-92b-3p and the luciferase assay revealed the suppressed CREB3L2 expression by miR-92b-3p. Mechanistically, we found that miR-92b-3p promotes the activation of HSCs and thereby the progression of liver fibrosis by activating JAK/STAT pathway via targeting CREB3L2, providing a new target for the diagnosis and treatment of liver fibrosis.

Clinical and molecular characterization of primary sclerosing epithelioid fibrosarcoma of bone and review of the literature.

Sclerosing epithelioid fibrosarcoma (SEF) is a rare sarcoma subtype characterized by monomorphic epithelioid cells embedded in a densely sclerotic collagenous matrix. The overwhelming majority of tumors arise in soft tissues; however, rare cases have been documented to occur primarily in bone. The hallmarks of soft tissue SEF include MUC4 immunoreactivity and the presence of an EWSR1-CREB3L1 fusion. Rare cases with alternative fusions have also been reported such as EWSR1-CREB3L2 and FUS-CREB3L2 transcripts. The molecular alterations of skeletal SEF have not been well-defined, with only rare cases analyzed to date. In this study we investigated the clinicopathologic and molecular features of seven patients presenting with primary osseous SEF. There were 3 males and 4 females, with a mean age at diagnosis of 38 years. All cases had microscopic features within the histologic spectrum of SEF and showed strong and diffuse MUC4 positivity, while lacking SATB2 expression. However, due to its unusual presentation within bone, four cases were initially misinterpreted as either osteosarcoma, Ewing sarcoma or chondroblastoma. Half of the patients with follow-up data developed metastasis. The cases were tested by targeted RNA sequencing, MSK-IMPACT, and/or fluorescence in situ hybridization, showing EWSR1-CREB3L1 in six cases and EWSR1-CREB3L2 in one case. The fusion transcripts were composed of EWSR1 exon 11 to either exon 6 of CREB3L1 or CREB3L2. In summary, due to their rarity in the bone, skeletal SEF are often misdiagnosed, resulting in inadequate treatment modalities. Similar to their soft tissue counterpart, bone SEF follow an aggressive clinical behavior and show similar EWSR1-CREB3L1/CREB3L2 fusions.

Promotion of Axon Growth by the Secreted End of a Transcription Factor.

Axon growth is regulated externally by attractive and repulsive cues generated in the environment. In addition, intrinsic pathways govern axon development, although the extent to which axons themselves can influence their own growth is unknown. We find that dorsal root ganglion (DRG) axons secrete a factor supporting axon growth and identify it as the C terminus of the ER stress-induced transcription factor CREB3L2, which is generated by site 2 protease (S2P) cleavage in sensory neurons. S2P and CREB3L2 knockdown or inhibition of axonal S2P interfere with the growth of axons, and C-terminal CREB3L2 is sufficient to rescue these effects. C-terminal CREB3L2 forms a complex with Shh and stabilizes its association with the Patched-1 receptor on developing axons. Our results reveal a neuron-intrinsic pathway downstream of S2P that promotes axon growth.

Low-grade fibromyxoid sarcoma: Clinical, morphologic and genetic features.

Low-grade fibromyxoid sarcoma (LGFMS) is a bland spindle cell neoplasm that typically arises in the deep soft tissues of the proximal extremities or trunk of young adults. The majority of LGFMS are characterized by a recurrent (7;16)(q34;p11) translocation, resulting in the FUS-CREB3L2 fusion gene, which generates a chimeric protein with transcriptional regulatory activity. Small numbers harbor a FUS-CREB3L1 fusion resulting from t(11;16)(p11;p11), whilst rare cases harbor the EWSR1-CREB3L1 fusion. LGFMS is of low to moderate cellularity and consists of bland spindle cells with small, angulated nuclei and scant, wispy cytoplasm, arranged in a whorled growth pattern and typically showing abrupt transition from myxoid to fibrous areas. Immunohistochemical expression of MUC4 is a consistent finding. Hyalinized spindle cell tumor with giant rosettes (HSCTGR) is a morphological variant of LGFMS that shares the same balanced translocation, and is also immunoreactive for MUC4. A potential relationship between LGFMS and sclerosing epithelioid fibrosarcoma (SEF), a rare fibroblastic neoplasm that most commonly arises in the deep soft tissues of the lower extremities, limb girdles or trunk, has also been suggested. SEF is classically composed of nests and cords of epithelioid cells with clear or eosinophilic cytoplasm embedded within densely sclerotic stroma. In some cases, areas indistinguishable from LGFMS are present, and these have been shown to contain FUS-CREB3L2 fusion transcripts. The majority of pure SEF tumors harbor EWSR1 rearrangements, with EWSR1-CREB3L1 and more rarely EWSR1-CREB3L2 gene fusions more common than those involving FUS. MUC4 immunoreactivity is also seen in approximately 70% of SEF. Surgical resection of these tumors with clear margins is the treatment of choice. Correct diagnosis is important because of the significant potential for recurrence and late metastatic spread. We review LGFMS and SEF, discussing morphology and immunohistochemistry, genetics and molecular findings, and the differential diagnosis.

DOG1 Expression in Low-Grade Fibromyxoid Sarcoma: A Study of 11 Cases, With Molecular Characterization.

DOG1 is a highly sensitive marker for gastrointestinal stromal tumor (GIST) and is in the routine diagnostic antibody repertoire of many surgical pathology laboratories. Moreover, GIST is well recognized by both pathologists and clinicians in the differential diagnosis of intra-abdominal and pelvic neoplasms. Low-grade fibromyxoid sarcoma (LGFMS) is, however, much less frequently anticipated, particularly when occurring at unusual sites, because of its rarity and bland histology, particularly on core biopsy. We describe a case of a 53-year-old male with a large pelvic and pararectal mass, which on biopsy showed a moderately cellular spindle cell neoplasm within fibrous stroma. Immunohistochemistry at the referring center showed diffuse and strong expression of DOG1 with negativity for other markers. After referral to a tertiary center, repeat DOG1 immunohistochemistry again showed diffuse expression, but MUC4 was also positive, and this was confirmed to be LGFMS, harboring FUS-CREB3L2 fusion transcripts by reverse transcription-polymerase chain reaction and FUS rearrangement with fluorescence in situ hybridization. In view of this we assessed DOG1 expression in 10 other LGFMS (all MUC4 positive, and 9 molecularly confirmed to harbor FUS-CREB3L2 fusion transcripts and/or FUS or EWSR1 gene rearrangement), of which 5 showed DOG1 expression in up to 75% of tumor cells, varying in intensity from weak to strong. While LGFMS and GIST are generally morphologically dissimilar, less typical variants of each exist, and both can contain bland spindled cells within fibrous stroma. As the morphologic spectrum of LGFMS is wide, and as it can occur in unusual sites and may not be well recognized by general pathologists and non-soft tissue pathologists, we highlight the potential for diagnostic confusion with GIST owing to aberrant DOG1 expression. This is clinically pertinent, as the management and prognosis of these 2 neoplasms differs significantly.

A case of low-grade fibromyxoid sarcoma with unusual central necrosis in a 77-year-old man confirmed by FUS-CREB3L2 gene fusion.

INTRODUCTION: Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue tumor typically affecting young to middle-aged adults. Despite its otherwise benign histologic appearance and indolent nature, it can display fully malignant behavior, and recurrence and metastasis can occur even decades after diagnosis. PRESENTATION OF CASE: Herein, we report a case of LGFMS in the buttock of a 77-year-old man. Magnetic resonance imaging uncovered a well-demarcated tumor measuring 27×20mm with a slightly high intensity on T1-weighted images (WIs) and heterogeneously high intensity on T2-WIs. Histologically, the tumor was composed of bland spindle-shaped cells in a whorled growth pattern with alternating fibrous and myxoid stroma. The tumor stroma was variably hyalinized with arcades of curvilinear capillaries and arterioles with associated perivascular fibrosis. Unusual histology, such as central necrosis and cystic formation, was also noted. Reverse transcription polymerase chain reaction from a formalin-fixed, paraffin-embedded biopsy specimen revealed a FUS-CREB3L2 gene fusion (exon6/int/exon5), leading to the diagnosis of LGFMS. DISCUSSION: To the best of our knowledge, this is the second oldest patient to be diagnosed with LGFMS. CONCLUSION: At the time of this report, the patient was alive with no evidence of the disease 4 months after diagnosis without any adjuvant therapy.