Pathogenesis of NUT midline carcinoma

Molecularly Defined Thoracic Neoplasms

Molecularly defined neoplasms are increasingly recognized, given the broader application and performance of molecular studies. These studies allow us to better characterize these neoplasms and learn about their pathogenesis. In the thorax, molecularly defined neoplasms include tumors such as NUT carcinoma, SMARCA4-deficient undifferentiated tumor (DUT), primary pulmonary myxoid sarcoma with EWSR1::CREB1 fusion, hyalinizing clear cell carcinoma, and SMARCB1-deficient neoplasms. Overall, these tumors are rare but are now more often recognized given more widely available immunostains such as NUT (NUT carcinoma), BRG1 (SMARCA4-DUT), and INI-1 (SMARCB1-deficient neoplasm). Furthermore, cytogenetic studies for EWSR1 to support a hyalinizing clear cell carcinoma or primary pulmonary myxoid sarcoma are, in general, easily accessible. This enables pathologists to recognize and diagnose these tumors. The diagnosis of these tumors is important for clinical management and treatment. For instance, clinical trials are available for patients with NUT carcinoma, SMARCA4-DUT, and SMACRB1-deficient neoplasms. Herein, our current knowledge of clinical, morphologic, immunophenotypic, and molecular features of NUT carcinomas, SMARCA4-DUT, primary pulmonary myxoid sarcomas, hyalinizing clear cell carcinoma, and SMARCB1-deficient neoplasms will be reviewed.

Unlocking the secrets of aging: Epigenetic reader BRD4 as the target to combatting aging-related diseases

BACKGROUND

Aging, a complex and profound journey, leads us through a labyrinth of physiological and pathological transformations, rendering us increasingly susceptible to aging-related diseases. Emerging investigations have unveiled the function of bromodomain containing protein 4 (BRD4) in manipulating the aging process and driving the emergence and progression of aging-related diseases.

AIM OF REVIEW

This review aims to offer a comprehensive outline of BRD4's functions involved in the aging process, and potential mechanisms through which BRD4 governs the initiation and progression of various aging-related diseases.

KEY SCIENTIFIC CONCEPTS OF REVIEW

BRD4 has a fundamental role in regulating the cell cycle, apoptosis, cellular senescence, the senescence-associated secretory phenotype (SASP), senolysis, autophagy, and mitochondrial function, which are involved in the aging process. Several studies have indicated that BRD4 governs the initiation and progression of various aging-related diseases, including Alzheimer's disease, ischemic cerebrovascular diseases, hypertension, atherosclerosis, heart failure, aging-related pulmonary fibrosis, and intervertebral disc degeneration (IVDD). Thus, the evidence from this review supports that BRD4 could be a promising target for managing various aging-related diseases, while further investigation is warranted to gain a thorough understanding of BRD4's role in these diseases.

Nuclear Protein in Testis (NUT) Carcinoma: A Comprehensive Immunohistochemical Analysis of 57 Cases With Consideration of Interpretation and Pitfall Recognition

CONTEXT.—

Nuclear protein in testis (NUT) carcinoma is an aggressive carcinoma defined by NUTM1 gene rearrangement. Diagnostic challenges include morphologic overlap with poorly differentiated squamous cell carcinoma, small cell carcinoma, thoracic SMARCA4-deficient undifferentiated tumor, and other small round blue cell tumors.

OBJECTIVE.—

To comprehensively study the immunohistochemistry (IHC) features of a large cohort of NUT carcinomas.

DESIGN.—

Fifty-seven NUT carcinoma cases were identified from 2012-2022, including 38 thoracic/mediastinal, 13 head and neck/sinonasal, and 6 from other sites. Pathology reports and available slides were reviewed. Comprehensive IHC studies were performed on available cases.

RESULTS.—

Keratin stains showed variable positivity and were entirely negative in 15% (8 of 55) of cases. p40 was only positive in 65% (24 of 37) of cases, implying inferior sensitivity when compared to p63 (87% sensitivity, 20 of 23 cases) and other squamous cell markers. Neuroendocrine markers were focally/weakly positive in few cases; however, INSM1 was positive in 54% (7 of 13) of cases, indicating a possible diagnostic pitfall. TTF-1 was mostly negative with focal positivity in 26% (10 of 38) of cases. Occasional CD34 (15%, 3 of 20 cases) and CD99 (21%, 3 of 14 cases) positivity could also cause potential diagnostic confusion. S100, desmin, CD45, and SALL4 were rarely positive. BRG1 and INI1 were retained in all cases. Ki-67 proliferative index was high (median, 60%). PD-L1 was negative in all tested cases.

CONCLUSIONS.—

This comprehensive IHC study demonstrates the immunohistochemical spectrum of NUT carcinoma. The findings can help narrow the differential diagnosis and recognize potential pitfalls.

A Review of the Bromodomain and Extraterminal Domain Epigenetic Reader Proteins: Function on Virus Infection and Cancer

The BET (bromodomain and extraterminal domain) family of proteins, particularly BRD4 (bromodomain-containing protein 4), plays a crucial role in transcription regulation and epigenetic mechanisms, impacting key cellular processes such as proliferation, differentiation, and the DNA damage response. BRD4, the most studied member of this family, binds to acetylated lysines on both histones and non-histone proteins, thereby regulating gene expression and influencing diverse cellular functions such as the cell cycle, tumorigenesis, and immune responses to viral infections. Given BRD4's involvement in these fundamental processes, it is implicated in various diseases, including cancer and inflammation, making it a promising target for therapeutic development. This review comprehensively explores the roles of the BET family in gene transcription, DNA damage response, and viral infection, discussing the potential of targeted small-molecule compounds and highlighting BET proteins as promising candidates for anticancer therapy.

Brd4::Nutm1 fusion gene initiates NUT carcinoma in vivo

NUT carcinoma (NC) is an aggressive cancer with no effective treatment. About 70% of NUT carcinoma is associated with chromosome translocation events that lead to the formation of a BRD4::NUTM1 fusion gene. Because the BRD4::NUTM1 gene is unequivocally cytotoxic when ectopically expressed in cell lines, questions remain on whether the fusion gene can initiate NC. Here, we report the first genetically engineered mouse model for NUT carcinoma that recapitulates the human t(15;19) chromosome translocation in mice. We demonstrated that the mouse t(2;17) syntenic chromosome translocation, forming the Brd4::Nutm1 fusion gene, could induce aggressive carcinomas in mice. The tumors present histopathological and molecular features similar to human NC, with enrichment of undifferentiated cells. Similar to the reports of human NC incidence, Brd4::Nutm1 can induce NC from a broad range of tissues with a strong phenotypical variability. The consistent induction of poorly differentiated carcinoma demonstrated a strong reprogramming activity of BRD4::NUTM1. The new mouse model provided a critical preclinical model for NC that will lead to better understanding and therapy development for NC.

Oral and oropharyngeal NUT carcinoma: a multicentre screening study of poorly differentiated oral cancer

BACKGROUND AND AIMS

Nuclear protein testis (NUT) carcinoma (NC) is a rare and highly aggressive tumour characterised by chromosomal rearrangement of the nuclear protein testis family member 1 (NUTM1) gene, also known as the NUT gene. NC occurs mainly in the head and neck, mediastinum and lung. In general, primary NC in the oral cavity is extremely rare and reported sporadically.

METHODS

A total of 111 formalin-fixed and paraffin-embedded specimens of poorly differentiated oral and oropharyngeal tumours were collected from 10 hospitals. NUT protein IHC staining was performed on these samples, and fluorescence in-situ hybridisation (FISH) and RNA sequencing detection were further carried out for NUT IHC-positive cases.

RESULTS

The expression of NUT protein in tumour cells was detected in five cases (five of 111, 4.5%). The tumours in these cases were located in the oral floor, lip, base of the tongue, gingiva and hard palate. FISH detection results showed BRD4::NUT rearrangement in three patients and a non-BRD4::NUT rearrangement pattern in two patients. RNA sequencing results confirmed BRD4::NUT rearrangement in two cases.

CONCLUSIONS

To our knowledge, this is the first and largest retrospective study of oral NC, and we found that NC is easily misdiagnosed as poorly differentiated oral squamous cell carcinoma (SCC) or poorly differentiated carcinoma. The morphology and immunophenotype of four NC cases were similar to SCC, and abrupt keratinisation was observed in three cases. Therefore, it is necessary to detect NUT protein for NC screening in oral malignant tumours with these morphologies, especially for young patients who are more likely to be misdiagnosed with other types of cancer.

Initial Chemotherapy for Locally Advanced and Metastatic NUT Carcinoma

INTRODUCTION

NUT carcinoma (NC) is an underdiagnosed and aggressive poorly differentiated or squamous cell cancer. A subset of NC is sensitive to chemotherapy, but the optimal regimen is unknown. Experts have recommended platinum- and ifosfamide-based therapy based on case reports.

METHODS

Patients with pathologically confirmed NC with known survival outcomes after chemotherapy and consented to participate in a worldwide registry were studied. Results were summarized using descriptive methods.

RESULTS

The study included 118 patients with NC. Median age was 34 (range: 1-82) years, 39% were women, and 61% harbored a BRD4::NUTM1 fusion. Patients received platinum (74%) or ifosfamide (26%, including regimens with both, 13%). Of 62 patients with nonmetastatic disease, 40% had a thoracic primary. Compared with platinum-based chemotherapy, patients who received ifosfamide-based chemotherapy had nominally higher progression-free survival (12 mo: 59% [95% CI: 32-87] versus 37% [95% CI: 22-52], hazard ratio = 0.68 [0.32, 1.42], p = 0.3) but not overall survival (OS). Among the 56 patients with metastatic disease, 80% had a thoracic primary. Ifosfamide had an objective response rate (ORR) of 75% (six of eight) and platinum had an ORR of 31% (11 of 36). Nevertheless, there was no difference in progression-free survival or OS. The 3-year OS of the entire cohort was 19% (95% CI: 10%-28%). Of the 11 patients alive greater than 3 years, all presented with nonmetastatic and operable or resectable disease.

CONCLUSION

There is a numerically higher ORR for ifosfamide-based therapy compared with platinum-based therapy, with limited durability. OS at 3 years is only 19%, and development of effective therapies is an urgent unmet need for this patient population.

NUT carcinoma in pediatric patients: Characteristics, therapeutic regimens, and outcomes of 11 cases registered with the German Registry for Rare Pediatric Tumors (STEP)

BACKGROUND AND AIMS

Nuclear protein of the testis (NUT) carcinoma (NC) is a rare and highly aggressive tumor defined by the presence of a somatic NUTM1 rearrangement, occurring mainly in adolescents and young adults. We analyzed the clinical and biological features of German pediatric patients (≤18 years) with NC.

METHODS

This study describes the characteristics and outcome of 11 children with NC registered in the German Registry for Rare Pediatric Tumors (STEP).

RESULTS

Eleven patients with a median age of 13.2 years (range 6.6-17.8) were analyzed. Malignant misdiagnoses were made in three patients. Thoracic/mediastinal tumors were found to be the primary in six patients, head/neck in four cases; one patient had multifocal tumor with an unknown primary. All patients presented with regional lymph node involvement, eight patients (72.7%) with distant metastases. Seven patients underwent surgery, eight radiotherapy with curative intent; polychemotherapy was administered in all patients. Novel treatment strategies including immunotherapy, targeted therapies, and virotherapy were applied in three patients. Median event-free survival and overall survival were 1.5 and 6.5 months, respectively.

CONCLUSIONS

Every undifferentiated or poorly differentiated carcinoma should undergo testing for the specific rearrangement of NUTM1, in order to initiate an intense therapeutic regimen as early as possible. As in adults, only few pediatric patients with NC achieve prolonged survival. Thus, novel therapeutic strategies should be included and tested in clinical trials.

Case report: Diagnosis of NUT carcinoma of hepatic origin by next-generation sequencing

NUT carcinoma is a rare subcategory of squamous cell carcinoma. The latter is primarily characterized by the fusion of the coding sequence NUTM1 on chromosome 15q14 with BRD4 or BRD3, both of which are acetyl-histone binding bromodomains. This tumor is often misdiagnosed due to its rarity and its histological similarity with other squamous cell carcinomas. It typically presents as a poorly differentiated squamous cell carcinoma in the head, neck, and mediastinal region, and has no distinct clinical characteristics that set it apart from other malignancies. Although uncommon, other NUT carcinomas have been reported in the literature outside of the midline region. Through next-generation sequencing, we were able to correctly diagnose our patient with the first-documented case of NUT carcinoma of hepatic-only origin.

BET Bromodomain Inhibitors: Novel Design Strategies and Therapeutic Applications

The mammalian bromodomain and extra-terminal domain (BET) family of proteins consists of four conserved members (Brd2, Brd3, Brd4, and Brdt) that regulate numerous cancer-related and immunity-associated genes. They are epigenetic readers of histone acetylation with broad specificity. BET proteins are linked to cancer progression due to their interaction with numerous cellular proteins including chromatin-modifying factors, transcription factors, and histone modification enzymes. The spectacular growth in the clinical development of small-molecule BET inhibitors underscores the interest and importance of this protein family as an anticancer target. Current approaches targeting BET proteins for cancer therapy rely on acetylation mimics to block the bromodomains from binding chromatin. However, bromodomain-targeted agents are suffering from dose-limiting toxicities because of their effects on other bromodomain-containing proteins. In this review, we provided an updated summary about the evolution of small-molecule BET inhibitors. The design of bivalent BET inhibitors, kinase and BET dual inhibitors, BET protein proteolysis-targeting chimeras (PROTACs), and Brd4-selective inhibitors are discussed. The novel strategy of targeting the unique C-terminal extra-terminal (ET) domain of BET proteins and its therapeutic significance will also be highlighted. Apart from single agent treatment alone, BET inhibitors have also been combined with other chemotherapeutic modalities for cancer treatment demonstrating favorable clinical outcomes. The investigation of specific biomarkers for predicting the efficacy and resistance of BET inhibitors is needed to fully realize their therapeutic potential in the clinical setting.

NUT carcinoma of the mandible in a child: case report and systematic review

Nuclear protein of the testis (NUT) carcinoma is a rare, undifferentiated carcinoma that is characterized by NUTM1 gene rearrangements. Patients with NUT carcinoma have an overall survival of approximately 5% at 5 years despite a multimodal treatment approach. This report illustrates the management of mandibular NUT carcinoma in a pediatric patient, complemented by a systematic review of head and neck NUT carcinoma. A 5-year-old female presented with an enlarging jaw mass that was diagnosed as BRD4-NUTM1 carcinoma and was treated with hemimandibulectomy and chemoradiation. She remains disease-free 21 months after completion of therapy. A total of 63 patient cases reported in 34 articles were identified in the review. Only 26.9% (14/52) of tumors were correctly diagnosed initially as NUT carcinoma, whereas 73.1% (38/52) were incorrectly diagnosed as another malignancy; the initial diagnosis was not reported for 11 patients. The mandibular tumor subtype was among the rarest reported (n = 1; 1.6%). Combination therapy, including surgery and chemoradiation, was the most common treatment (55.2%). The patient case presented here is a novel case of pediatric mandibular NUT carcinoma. Due to the poor overall survival of patients with NUT carcinoma, aggressive upfront resection with 2-cm margins followed by adjuvant chemoradiation is advocated.

Structural mechanism of BRD4-NUT and p300 bipartite interaction in propagating aberrant gene transcription in chromatin in NUT carcinoma

BRD4-NUT, a driver fusion mutant in rare and highly aggressive NUT carcinoma, acts in aberrant transcription of anti-differentiation genes by recruiting histone acetyltransferase (HAT) p300 and promoting p300-driven histone hyperacetylation and nuclear condensation in chromatin. However, the molecular basis of how BRD4-NUT recruits and activates p300 remains elusive. Here, we report that BRD4-NUT contains two transactivation domains (TADs) in NUT that bind to the TAZ2 domain in p300. Our NMR structures reveal that NUT TADs adopt amphipathic helices when bound to the four-helical bundle TAZ2 domain. The NUT protein forms liquid-like droplets in-vitro that are enhanced by TAZ2 binding in 1:2 stoichiometry. The TAD/TAZ2 bipartite binding in BRD4-NUT/p300 triggers allosteric activation of p300 and acetylation-driven liquid-like condensation on chromatin that comprise histone H3 lysine 27 and 18 acetylation and transcription proteins BRD4L/S, CDK9, MED1, and RNA polymerase II. The BRD4-NUT/p300 chromatin condensation is key for activating transcription of pro-proliferation genes such as ALX1, resulting ALX1/Snail signaling and epithelial-to-mesenchymal transition. Our study provides a previously underappreciated structural mechanism illuminating BRD4-NUT's bipartite p300 recruitment and activation in NUT carcinoma that nucleates a feed-forward loop for propagating histone hyperacetylation and chromatin condensation to sustain aberrant anti-differentiation gene transcription and perpetual tumor cell growth.

Clinical imaging of primary pulmonary nucleoprotein of the testis carcinoma

Objective

Primary pulmonary nucleoprotein of the testis (NUT) carcinoma is very rare in the clinic. In this study, the clinicopathological manifestations and imaging features of the primary pulmonary NUT carcinoma were investigated to improve the diagnosis of this disease.

Methods

Six patients with pathologically diagnosed pulmonary NUT carcinoma were analyzed, including three males and three females, aged 19-64 (49.00 ± 16.40) years, with clinical manifestations of cough in two cases, hoarseness in one case, blood in sputum in one case, chest pain in one case, and physical examination findings in one case, with a disease duration of 5 days to 4 months. The clinical and imaging data including CT and PET/CT were retrospectively analyzed. Further literature reviews were analyzed in both pulmonary and extrapulmonary NUT carcinoma cases who performed ¹⁸F-FDG PET/CT.

Results

Most of the patients with pulmonary NUT carcinomas presented as heterogeneous lobulated masses (83.33%), four cases (66.67%) were located in the upper lobe of the left lung, one case (16.67%) in the middle lobe of the right lung, and one case (16.67%) in the lower lobe of the right lung, with the maximum diameter ranging from 1.30 to 8.90 cm and the median of 3.55 cm, most of them were irregularly shaped, with more lobulated margins and more heterogeneous density (83.33%), and the enhancement was mild. PET/CT showed increased ¹⁸F-FDG uptake in the lesion and metastatic areas. Both the pulmonary NUT patients in this study and literature reviews showed the SUV_max of the tumor ranged from 5 to 40 with an average value of 12.8, whereas that of extrapulmonary lesions had a range of SUV_max at 4.5-64.1 and a mean of 13.8.

Conclusion

In patients with central lung masses, rapid disease progression, and poor response to initial treatment, the possibility of NUT cancer should be considered and anti-NUT monoclonal antibody immunohistochemical staining, combined with genetic detection, if necessary, should be performed as soon as possible. CT and PET/CT imaging are essential for the staging, management, treatment response assessment, and monitoring of pulmonary NUT cancer.

Multimodality imaging and treatment of paranasal sinuses nuclear protein in testis carcinoma: A case report

BACKGROUND

Nuclear protein in testis (NUT) carcinoma is a rare aggressive malignant epithelial cell tumor, previously known as NUT midline carcinoma (NMC), characterized by an acquired rearrangement of the gene encoding NUT on chromosome 15q14. Due to the lack of characteristic pathological features, it is often underdiagnosed and misdiagnosed. A variety of methods can be used to diagnose NMC, including immunohistochemistry, karyotyping, fluorescence in situ hybridization, reverse transcription-polymerase chain reaction, and next-generation sequencing. So far, there is no standard treatment plan for NMC and the prognosis is poor, related to its rapid progression, easy recurrence, and unsatisfactory treatment outcome.

CASE SUMMARY

A 58-year-old female came to our hospital with a complaint of eye swelling and pain for 8 d. The diagnosis of NMC was confirmed after postoperative pathology and genetic testing. The patient developed nausea and vomiting, headache, and loss of vision in both eyes to blindness after surgery. Magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) performed after 1.5 mo postoperatively suggested tumor recurrence. The patient obtained remission after radiation therapy to some extent and after initial treatment with anti-angiogenic drugs and sonodynamic therapy (SDT), but cannot achieve long-term stability and eventually developed distant metastases, with an overall survival of only 17 mo.

CONCLUSION

For patients with rapidly progressing sinus tumors and poor response to initial treatment, the possibility of NMC should be considered and immunohistochemical staining with anti-NUT should be performed as soon as possible, combined with genetic testing if necessary. CT, MRI, and PET/CT imaging are essential for the staging, management, treatment response assessment and monitoring of NMC. This case is the first attempt to apply heat therapy and SDT in the treatment of NMC, unfortunately, the prognosis remained poor.

NUT Carcinoma in Children and Adolescents: The Expert European Standard Clinical Practice Harmonized Recommendations

BACKGROUND AND AIMS

Nuclear protein of the testis (NUT) carcinoma (NC) is a rare and highly aggressive tumor mainly occurring in adolescents and young adults, defined by the presence of a somatic NUTM1 rearrangement. The aim is to establish internationally harmonized consensus recommendations for the diagnosis and treatment of adolescents and young adults with NC in the framework of the European Reference Network for Paediatric Oncology.

METHODS

The European Cooperative Study Group for Pediatric Rare Tumors developed recommendations according to the Consensus Conference Standard Operating procedure methodology and reviewed by external "experts." No evidence of level I to II exists. Recommendations were developed based on published prospective (level III), but more frequently retrospective series (level IV), case reports (level V), and personal expertise (level V). In addition, "strength" of recommendations were categorized by grading (grade A to E).

RESULTS

Histology is mandatory for the diagnosis of NC, including immunolabeling with anti-NUT antibodies and molecular biology (NUTM1 rearrangement) (level V; grade A). Treatment of NC usually combines aggressive approaches in multimodal regimens. Chemotherapy should be considered as first-line treatment (neoadjuvant vincristine-adriamycin-ifosfamide/cisplatin-adriamycin-ifsofamide or vincristine-doxorubicin-cyclophosphamide/ifosfamide-etoposide) for unresectable or metastatic tumor (ie, 3 courses), rapidly followed by local treatment (level IV; grade B). Referral to a specialized surgical oncology center is highly recommended (level V; grade A). In localized NC, a complete microscopic surgical resection should be attempted whenever and as soon as possible, followed by primary irradiation (60 to 70 Gy) and involved lymph nodes area (level IV; grade B). For head and neck tumors, a systematic neck dissection might be considered, even if N0 (level V; grade C). Adjuvant postirradiation chemotherapy is recommended, for a total of 9 to 12 courses (level IV; grade B). For first-line resected tumors, concomitant adjuvant chemotherapy to radiotherapy may be discussed (level IV; grade B). Targeted therapies and immunotherapeutic regimens should be delivered in the setting of prospective trials (level V; grade B).

CONCLUSIONS

This project leads to a consensus strategy based on international experience with this very rare disease.

Possible Primary Thyroid Nuclear Protein in Testis Carcinomas with NSD3::NUTM1 Translocation Revealed by RNA Sequencing: A Report of Two Cases

Background: Nuclear protein in testis (NUT) carcinomas (NC) are a rare, highly aggressive, subset of squamous cell carcinomas, characterized by a translocation involving the NUTM1 gene. Thyroid location of NUT carcinomas has rarely been described. Methods: We report here two cases of thyroid NC with NSD3::NUTM1 translocation. Results: The first case presented as a very aggressive undifferentiated thyroid carcinoma in a 38-year-old man who died 21 months after the diagnosis. The second case was diagnosed after multiple lymphadenopathy recurrences mainly in the neck in a 37-year-old woman 7 years after total thyroidectomy for papillary thyroid carcinoma with a classic and a solid/trabecular component. Conclusions: Our case reports highlight the challenges in diagnosing these exceptional carcinomas. The therapeutic impact of the administration of pharmacological compounds with epigenetic action, in line with the physiopathology of these carcinomas, is also discussed.

NUT Is a Driver of p300-Mediated Histone Hyperacetylation: From Spermatogenesis to Cancer

Simple Summary

The functional characterization of the BRD4-NUT fusion protein as the driver of the highly aggressive NUT Carcinoma is fundamental to the understanding of the mechanisms responsible for the genome-wide hyperacetylation of histones prior to their eviction during the final stages of sperm cells maturation.

Abstract

In maturing sperm cells, a major genome re-organization takes place, which includes a global increase in the acetylation of histones prior to their replacement by protamines, the latter being responsible for the tight packaging of the male genome. Understanding the function of the oncogenic BRD4-NUT fusion protein in NUT carcinoma (NC) cells has proven to be essential in uncovering the mechanisms underlying histone hyperacetylation in spermatogenic cells. Indeed, these studies have revealed the mechanism by which a cooperation between BRD4, a bromodomain factor of the BET family, NUT, a normally testis-specific factor, and the histone acetyltransferase p300, induces the generation of hyperacetylated chromatin domains which are present in NC cells. The generation of Nut ko mice enabled us to demonstrate a genetic interaction between Nut and Brdt, encoding BRDT, a testis-specific BRD4-like factor. Indeed, in spermatogenic cells, NUT and p300 interact, which results in an increased acetylation of histone H4 at both positions K5 and K8. These two positions, when both acetylated, are specifically recognized by the first bromodomain of BRDT, which then mediates the removal of histone and their replacement by protamines. Taken together, these investigations show that the fusion of NUT to BRD4 in NUT Carcinoma cells reconstitutes, in somatic cells, a functional loop, which normally drives histone hyperacetylation and chromatin binding by a BET factor in spermatogenic cells.

A Comprehensive Review of BET Protein Biochemistry, Physiology, and Pathological Roles

Epigenetic modifications, specifically acetylation of histone plays a decisive role in gene regulation and transcription of normal cellular mechanisms and pathological conditions. The bromodomain and extraterminal (BET) proteins (BRD2, BRD3, BRD4, and BRDT), being epigenetic readers, ligate to acetylated regions of histone and synchronize gene transcription. BET proteins are crucial for normal cellular processing as they control cell cycle progression, neurogenesis, differentiation, and maturation of erythroids and spermatogenesis, etc. Research-based evidence indicated that BET proteins (mainly BRD4) are associated with numeral pathological ailments, including cancer, inflammation, infections, renal diseases, and cardiac diseases. To counter the BET protein-related pathological conditions, there are some BET inhibitors developed and also under development. BET proteins are a topic of most research nowadays. This review, provides an ephemeral but comprehensive knowledge about BET proteins’ basic structure, biochemistry, physiological roles, and pathological conditions in which the role of BETs have been proven. This review also highlights the current and future approaches to pledge BET protein-related pathologies.

NUT Carcinoma: Clinicopathologic Features, Molecular Genetics and Epigenetics

Nuclear protein in testis (NUT) carcinoma is a rare, highly aggressive, poorly differentiated carcinoma occurring mostly in adolescents and young adults. This tumor usually arises from the midline structures of the thorax, head, and neck, and exhibits variable degrees of squamous differentiation. NUT carcinoma is defined by the presence of a NUTM1 (15q14) rearrangement with multiple other genes. In about 70-80% of the cases, NUTM1 is involved in a balanced translocation with the BRD4 gene (19p13.12), leading to a BRD4-NUTM1 fusion oncogene. Other variant rearrangements include BRD3-NUTM1 fusion (~15-20%) and NSD3-NUTM1 fusion (~6%), among others. The diagnosis of NUT carcinoma requires the detection of nuclear expression of the NUT protein by immunohistochemistry. Additional methods for diagnosis include the detection of a NUTM1 rearrangement by fluorescence in situ hybridization or by reverse transcriptase PCR. NUT carcinoma is usually underrecognized due to its rarity and lack of characteristic histological features. Therefore, the goal of this review is to provide relevant recent information regarding the clinicopathologic features of NUT carcinoma, the role of the multiple NUTM1 gene rearrangements in carcinogenesis, and the impact of understanding these underlying molecular mechanisms that may result in the development of possible novel targeted therapies.

Intra-, para-, and suprasellar nuclear protein of testis carcinoma with infiltration of cavernous sinus and clivus-a case report

A nuclear protein of testis (NUT) carcinoma, also known as NUT midline carcinoma, is a rare subtype of squamous carcinoma known for its aggressive growth behaviour. It can form anywhere in the body. Although, it usually occurs along midline structures (head, neck, lungs). The authors present the first report of intrasellar NUT carcinoma with cavernous sinus infiltration in a 47-year-old patient. MRI showed an inhomogeneous, gadolinium-enhancing lesion with intra- and suprasellar growth, invasion of the cavernous sinus without clear differentiation from normal pituitary tissue. Given the lymphoma diagnosis in the frozen section and invasion of the cavernous sinus, the patient underwent endoscopic, transnasal, and transsphenoidal subtotal resection only. Local tumour and spinal metastases showed a good response to radio-chemotherapy. Despite combined radio-chemotherapy, the patient died of pulmonary insufficiency due to rapid progression of pulmonary metastasis 6 months after the initial diagnosis.

Primary Thyroid NUT Carcinoma With High PD-L1 Expression and Novel Massive IGKV Gene Fusions: A Case Report With Treatment Implications and Literature Review

Background

Nuclear protein in testis (NUT) carcinoma (NC) is a rare and aggressive undifferentiated carcinoma that typically arises from midline supradiaphragmatic structures. It is uniquely driven by a NUT gene rearrangement on chromosome 15q14. Few thyroid NCs have been reported and there are no established treatment guidelines for NUT carcinoma.

Method

Ultrasound-guided fine needle aspiration smear was performed for the preoperative diagnosis of thyroid lesions. Cytopathology, histology, and immunochemical staining all indicated NC. Fluorescence in situ hybridization (FISH), qRT-PCR, and next-generation sequencing (NGS) were used to analyze the genetic characteristics of NC.

Results

We describe a rare case of thyrogenic NC in a 38-year-old male with cytological, histological, immunohistochemical, and genetic features. Cytological smears and histopathological specimens showed typical features of NC. Immunohistochemistry confirmed strong immunoreactivity with NUT, EMA, P63, TTF-1, and c-myc. CK19 was positive exclusively in sudden keratosis. No immunoreactivity was found for neuroendocrine markers. FISH was applied to isolate the NUT gene on chromosome 15q14. The NGS results revealed a BRD4-NUT gene fusion, which was further confirmed by RT-qPCR. Structural variation (SV) of NUTM1 occurred in the exon region, and the mutation site was 15q14. Moreover, BRD4 single-nucleotide variation (SNV) occurs in the 3′ UTR at mutation site 19p13.12. The PD-L1 combined predictive score was over 30%. The patient received chemotherapy, followed by programmed cell death 1 (PD-1) inhibition with camrelizumab, and died 10 months after surgery.

Conclusion

Thyroid NC is an extremely rare and fatal malignant tumor. It is necessary to consider NC when squamous differentiation is observed cytologically or histologically. NGS is an effective tool for obtaining the final diagnosis and obtaining a better understanding of tumor pathogenesis. A large number of IGKV gene fusions in addition to the BRD4-NUT fusion may play a role in the pathogenesis and immunotherapy response of NC. Immunotherapy for NC remains to be explored due to the rarity of this aggressive malignancy.

NUT midline carcinoma as a primary lung tumor treated with anlotinib combined with palliative radiotherapy: a case report

Background

NUT (nuclear protein in testis) midline carcinoma (NMC) is a rapidly progressive tumor arising from midline structures. Recent cases have reported that the poor prognosis with a median survival of 6.7 months and a 2 years overall survival of 19% due to limited treatment. Based on the effect of arotinib on inhibiting tumor growth and angiogenesis. We present one patient case treated with anlotinib and radiotherapy.

Case presentation

Here, we describe a 33-year old patient who complained of cough and chest pain and was diagnosed as a pulmonary NMC through CT scan, FISH and immunohistochemistry. In addition, we initially demonstrated that anlotinib combined with palliative radiotherapy could significantly prevent the tumor growth in a pulmonary NMC.

Conclusion

The report indicated that anlotinib combined with palliative radiotherapy could inhibit the tumor progression in a pulmonary NMC, which may provide a combined therapy to pulmonary NMC in the future.

Case report: NUT carcinoma with MXI1::NUTM1 fusion characterized by abdominopelvic lesions and ovarian masses in a middle-aged female

Background

Nuclear protein of the testis (NUT) carcinoma is a rare subset of poorly differentiated, highly aggressive malignancy defined by NUTM1 gene rearrangements. Only three NUT cases of probable ovarian origin have been reported.

Case presentation

We report a case of NUT carcinoma in a 53-year-old female who presented with extensive abdominopelvic lesions and bilateral ovarian masses suggestive of advanced ovarian cancer. This patient was admitted to our hospital due to abdominal pain and distension for over two months. Imaging examinations suggested a possible malignancy of bilateral adnexal origin. This patient first underwent diagnostic laparoscopy. After receiving neoadjuvant chemotherapy, she underwent cytoreductive surgery. Surgical pathology showed infiltration of monotonous round tumor cells with no apparent differentiation characteristics. Immunohistochemistry (IHC) revealed nuclear expression of the NUT protein. And MXI1::NUTM1 fusion was identified by next-generation sequencing (NGS). Herein, we introduce an unusual NUT carcinoma and describe the clinical, imaging, and pathological features. In addition, we briefly reviewed the published literature and discussed the possibility of primary gynecological NUT carcinoma.

Conclusions

Identifying a NUT carcinoma arising from the abdominopelvic cavity is essential, and we underscore the need for NUT testing in undifferentiated malignant neoplasms that appear in this clinical setting. Although it is unclear from which origin this tumor arose, proper classification is essential for treatment planning.

A Poorly Differentiated Non-keratinizing Sinonasal Squamous Cell Carcinoma with a Novel ETV6-TNFRSF8 Fusion Gene

Squamous cell carcinoma of the sinonasal tract is relatively rare and morphologically and genetically heterogeneous. We report the case of an adult male with a left sphenoid sinus mass. A biopsy revealed an undifferentiated carcinoma composed of sheets of epithelioid cells lacking keratinization and glandular formation. The tumor was associated with a prominent lymphoplasmacytic inflammatory infiltrate. Immunohistochemical staining demonstrated diffuse expression of pankeratin and p63; it was negative for p16. In addition, EBER was also negative. Morphologically the findings raised the possibility of non-keratinizing squamous cell carcinoma. RNA sequencing was undertaken to exclude the possibility of NUT carcinoma; interestingly, this revealed a novel ETV6-TNFRSF8 fusion transcript, which was independently confirmed by fluorescence in situ hybridization. The current case is illustrative because it broadens our understanding of the molecular pathogenesis of non-keratinizing squamous cell carcinoma and adds to the diversity of ETV6-rearranged malignancies.

Immunotherapy and Targeting the Tumor Microenvironment: Current Place and New Insights in Primary Pulmonary NUT Carcinoma

Primary pulmonary nuclear protein of testis carcinoma is a rare and highly aggressive malignant tumor. It accounts for approximately 0.22% of primary thoracic tumors and is little known, so it is often misdiagnosed as pulmonary squamous cell carcinoma. No effective treatment has been formed yet, and the prognosis is extremely poor. This review aims to summarize the etiology, pathogenesis, diagnosis, treatment, and prognosis of primary pulmonary nuclear protein of testis carcinoma in order to better recognize it and discuss the current and innovative strategies to overcome it. With the increasing importance of cancer immunotherapy and tumor microenvironment, the review also discusses whether immunotherapy and targeting the tumor microenvironment can improve the prognosis of primary pulmonary nuclear protein of testis carcinoma and possible treatment strategies. We reviewed and summarized the clinicopathological features of all patients with primary pulmonary nuclear protein of testis carcinoma who received immunotherapy, including initial misdiagnosis, disease stage, immunohistochemical markers related to tumor neovascularization, and biomarkers related to immunotherapy, such as PD-L1 (programmed death-ligand 1) and TMB (tumor mutational burden). In the meanwhile, we summarized and analyzed the progression-free survival (PFS) and the overall survival (OS) of patients with primary pulmonary nuclear protein of testis carcinoma treated with PD-1 (programmed cell death protein 1)/PD-L1 inhibitors and explored potential population that may benefit from immunotherapy. To the best of our knowledge, this is the first review on the exploration of the tumor microenvironment and immunotherapy effectiveness in primary pulmonary nuclear protein of testis carcinoma.

[A Case Report of Primary Pulmonary NUT Carcinoma and Literature Review]

NUT癌是以染色体15q14上睾丸核蛋白（nuclear protein in testis, NUTM1）重排为特征的一种罕见的恶性程度极高的肿瘤，其发病机制及治疗方法目前尚不明确，其预后极差。因其好发部位主要集中在躯体中线位置，如眼眶、鼻腔、上颚、纵隔等，故又称为中线癌。四川大学华西医院胸部肿瘤科收治了1例肺NUT癌患者，为70岁老年男性，初诊为体检发现左肺门占位，术后病理提示低分化癌，经荧光标记的原位杂交技术证实为NUT癌，术后经化疗、抗血管治疗、放疗等综合治疗获得了较长的生存期。本文结合文献回顾报告了肺NUT癌这一少见实体瘤的临床、病理特征及治疗策略。

Clinical, Radiographic, Pathologic Characterization and Survival Outcomes of Nuclear Protein of the Testis Carcinoma

INTRODUCTION

Nuclear protein of the testis (NUT) carcinoma (formerly NUT midline carcinoma) is an aggressive tumor with characteristic BRD4-NUTM1 translocation and a poor prognosis. The primary objective of this study was to describe the clinical and radiologic features, treatment response, and survival of NUT carcinoma (NC).

MATERIALS AND METHODS

This retrospective single-center study was based on the review of medical records of NC patients with a specific genetic rearrangement or positive anti-NUT nuclear staining. Overall survival (OS) was analyzed according to primary tumor location.

RESULTS

This series of 22 patients had a mean age of 36.27 ± 2.68 years with 68% women and 32% men. The median age at diagnosis was 34 years (range, 17-55 years). The primary tumor was located in the chest (n = 12/22; 55%), head and neck (n = 9/22; 40%), and 1 patient had a renal tumor. About 68% (n = 15/22) patients presented with regional lymph nodal involvement and 77% (n = 17/22) had distant metastases. All the bone metastases were lytic (100%) with mixed lytic and sclerotic metastases in 5 patients. Only 18% (n = 4/22) of the patients showed response to treatment, with progression in the remaining 18 patients. The median OS was 7 months. The OS was significantly (P = 0.024) more in patients with primary head and neck NC (n = 9; OS, 16 months) versus those with pulmonary and other locations (n = 13; OS, 6 months).

CONCLUSIONS

Nuclear protein of the testis carcinoma is an aggressive disease refractory to conventional therapy. Imaging with the complementary use of computed tomography, magnetic resonance imaging, and positron emission tomography/computed tomography is important for staging, guiding management, assessing the treatment response, and surveillance.

Chemical Screen Identifies Diverse and Novel Histone Deacetylase Inhibitors as Repressors of NUT Function: Implications for NUT Carcinoma Pathogenesis and Treatment

NUT carcinoma (NC), characterized most commonly by the BRD4-NUTM1 fusion, is a rare, aggressive variant of squamous carcinoma with no effective treatment. BRD4-NUT drives growth and maintains the poorly differentiated state of NC by activating pro-growth genes such as MYC, through the formation of massive, hyperacetylated, superenhancer-like domains termed megadomains. BRD4-NUT-mediated hyperacetylation of chromatin is facilitated by the chromatin-targeting tandem bromodomains of BRD4, combined with NUT, which recruits the histone acetyltransferase, p300. Here, we developed a high-throughput small-molecule screen to identify inhibitors of transcriptional activation by NUT. In this dCAS9-based GFP-reporter assay, the strongest hits were diverse histone deacetylase (HDAC) inhibitors. Two structurally unrelated HDAC inhibitors, panobinostat and the novel compound, IRBM6, both repressed growth and induced differentiation of NC cells in proportion to their inhibition of NUT transcriptional activity. These two compounds repressed transcription of megadomain-associated oncogenic genes, such as MYC and SOX2, while upregulating pro-differentiation, non-megadomain-associated genes, including JUN, FOS, and key cell-cycle regulators, such as CDKN1A. The transcriptional changes correlate with depletion of BRD4-NUT from megadomains, and redistribution of the p300/CBP-associated chromatin acetylation mark, H3K27ac, away from megadomains toward regular enhancer regions previously populated by H3K27ac. In NC xenograft models, we demonstrated that suppression of tumor growth by panobinostat was comparable with that of bromodomain inhibition, and when combined they improved both survival and growth suppression. IMPLICATIONS: The findings provide mechanistic and preclinical rationale for the use of HDAC inhibitors, alone or combined with other agents, in the treatment of NUT carcinoma.

NUT Carcinoma Without Upfront Surgical Resection: A Case Report

Nuclear protein in testis carcinoma is a rare and highly aggressive carcinoma associated with a 70% mortality rate 1 year from diagnosis and a median survival of only 6.5 months. No established treatment protocol exists, although some success has been achieved using a multimodal approach including early surgical resection and adjuvant chemotherapy and radiation. Prior studies have not demonstrated successful treatment in the absence of upfront surgical resection. We describe the first reported case of a patient with unresectable nuclear protein in testis carcinoma treated successfully with definitive chemotherapy using the Scandinavian Sarcoma Group IX Protocol and concurrent radiation therapy, but without surgical resection.

Incidence of NUT carcinoma in Western Australia from 1989 to 2014: a review of pediatric and adolescent cases from Perth Children's Hospital

Background

NUT carcinoma (NC), previously known as NUT midline carcinoma, is a rare and very aggressive cancer that occurs in both children and adults. NC is largely chemoresistant, with an overall survival of less than 7 months. Because the carcinoma is not restricted to a particular organ, diagnosis is often a challenge. In the absence of a clearly determined incidence for NC, we sought to study the diagnosis of patients in a well-defined population.

Methods

We systematically reviewed records of all patients that presented to the Oncology Department of the Princess Margaret Hospital for Children from 1989 to 2014. This institution in the geographically isolated state of Western Australia has a catchment population of around 2 million. We then identified all high grade undifferentiated sarcomas or carcinomas in the 0–16 year age group.

Results

Over 26 years, we found 14 patients of 16 years or younger with undifferentiated malignant tumors. Of these, five tumors were positive by immunohistochemistry for the NUT/NUTM1 (Nuclear Protein in Testis) protein and/or the translocation t(15;19). Three patients presented with thoracic tumors, one with a para-spinal tumor, and one had an upper airway nasopharyngeal carcinoma. In all five cases, there was an initial response to therapy and then progression. This 26-year survey was conducted in a geographically isolated state with a well-defined population, and we determined an estimated incidence of NC of around 0.41 per million child years (0–16 yrs. of age) at risk. From three patients it was feasible to derive cell lines for further genetic analyses and drug screening.

Conclusions

For the first time, the incidence of NC could be determined in a well-defined geographic area. The calculated rate of NC incidence is consistent with a history of under-recognition for this malignancy. These findings indicate that improved diagnostic detection of NC would enable better management and counselling of patients. Our findings emphasize the heterogeneity of NC, and they highlight the need to develop personalised therapy options, and to consider a diagnosis of NC in undifferentiated malignant tumors.

NUT Midline Carcinoma of the Lung: Computed Tomography Findings in 10 Patients

OBJECTIVE

The aim of the study was to evaluate computed tomography (CT) findings of pulmonary NUT midline carcinoma.

METHODS

We assessed clinical and CT features of pulmonary NUT carcinoma in 10 consecutive patients (M:F, 7:3; mean, 39 years).

RESULTS

The primary tumors (size range, 15-65 mm) manifested as either a peripheral tumor (5/10) or a central tumor (5/10). All tumors showed relatively low-attenuation at contrast-enhanced CT (mean net enhancement, 26 HU). Associated CT findings were metastatic hilar or mediastinal lymphadenopathy (8/10), ipsilateral pleural seeding with malignant pleural effusion (2/10), and distant metastasis (2/10). Five patients with low tumor-node-metastasis stages after optimal treatment showed no evidence of disease (50%) for 6 to 35 months.

CONCLUSIONS

Pulmonary NUT carcinoma presented as a peripheral or a central lung mass showing mild degree of contrast enhancement, frequent metastatic regional lymphadenopathy, affecting relatively young adults. Although known to be highly aggressive, an early diagnosis in low TNM stages can lead to a favorable prognosis.

Sinonasal NUT Carcinoma: Delayed Diagnosis Due to the COVID-19 Pandemic and a Review of the Literature

NUT carcinoma (NUT-C) is a relatively new malignancy that was recently listed in the 4th edition of the WHO Classification of Head and Neck Tumors in 2017. NUT carcinoma is a rare, aggressive, poorly differentiated carcinoma genetically defined by chromosomal rearrangement of the nuclear protein in testis (NUTM1) gene. The prognosis is extremely poor, with a mean survival < 1 year. Recent publications suggest a multimodality treatment approach. In the existing literature, only a few reports of sinonasal NUT-C have been reported. Sinonasal NUT-C is considered a very rare entity, but because of its recent inclusion as a head and neck malignancy, its true prevalence is unknown. We report the case of a 56-year-old woman with NUT-C of the sinonasal cavities. In the case reported, the coexistence of Coronavirus disease 2019 (COVID-19)-related nasal congestion delayed the diagnosis of NUT-C. Clinical presentation, diagnosis and treatment modalities are discussed together with a review of the literature.

Challenges and Opportunities in NUT Carcinoma Research

NUT carcinoma (NC) is a type of aggressive cancer driven by chromosome translocations. Fusion genes between a DNA-binding protein, such as bromodomain and extraterminal domain (BET) proteins, and the testis-specific protein NUTM1 generated by these translocations drive the formation of NC. NC can develop in very young children without significant accumulation of somatic mutations, presenting a relatively clean model to study the genetic etiology of oncogenesis. However, after 20 years of research, a few challenging questions still remain for understanding the mechanism and developing therapeutics for NC. In this short review, we first briefly summarize the current knowledge regarding the molecular mechanism and targeted therapy development of NC. We then raise three challenging questions: (1) What is the cell of origin of NC? (2) How does the germline analogous epigenetic reprogramming process driven by the BET-NUTM1 fusion proteins cause NC? and (3) How will BET-NUTM1 targeted therapies be developed? We propose that with the unprecedented technological advancements in genome editing, animal models, stem cell biology, organoids, and chemical biology, we have unique opportunities to address these challenges.

Identification of 3,5-Dimethylisoxazole Derivatives as BRD4 Inhibitors for the Treatment of Colorectal Cancer

Bromodomain-containing protein 4 (Brd4) plays a critical regulatory role in gene transcription that has been recently recognized as a promising strategy for cancer therapy. Based on the BRD4 protein containing two tandem bromodomain structures, BD1 and BD2, we designed and synthesized a series of 3,5-dimethylisoxazole derivative dimers targeting both bromodomains simultaneously to enhance protein binding potency. Among them, compound 22 significantly inhibited the proliferation of colorectal cancer cells HCT116 (IC₅₀ = 162 nM), with a 20-fold increase in antiproliferative activity compared to inhibitor 14. The results of WesternBlot showed that compound 22 could down-regulate c-MYC protein levels and up-regulate HEXIM1 expression and modulate apoptosis through intrinsic pathways. In addition, compound 22 exhibited outstanding antitumor efficacy in the CT-26 tumor mouse model with a tumor suppression rate of 56.1%. Taken together, 3,5-dimethylisoxazole derivative dimer 22 has remarkable protein inhibitory effect and antitumor activity in vitro and in vivo. A protein binding model of compound 22 is being further analyzed, which will facilitate the development of bivalent BRD4 inhibitors and probe the biological function of BRD4.

NUT midline carcinoma in a young pregnant female: a case report

INTRODUCTION

The NUT midline carcinoma is a rare tumor mostly reported in the midline of upper aerodigestive tract and mediastinum. Children as well as adolescents are affected without a gender distribution. A standard treatment is not established. So far, there exists no reported case of a pregnant female suffering from NUT midline carcinoma with musculoskeletal manifestation.

CASE PRESENTATION

A 34-year-old woman was referred to our outpatient clinic by the general practitioner during her 31st week of pregnancy suffering from shoulder pain and dyspnea. So far, dyspnea was interpreted as a typical pregnancy-related symptom. However, a chest X-ray showed a tumor mass in the right lung in close relation to the scapula. Further examinations found metastases in different areas of the body. No pregnancy-related complications were detected by obstetric examination. After an interdisciplinary perinatal case discussion, cesarean section was directly followed by an open biopsy of the right side scapula tumor lesion. A NUT midline carcinoma was diagnosed by immunohistochemistry. Due to disseminated tumor disease in multiple non-resectable locations, a palliative systemical chemotherapy was started by the oncological outpatient clinic.

CONCLUSION

This report presents the case of the very rare NUT midline carcinoma under pregnancy which made interdisciplinary case discussions indispensable for therapy planning.

Clinicopathological characteristics of primary lung nuclear protein in testis carcinoma: A single-institute experience of 10 cases

BACKGROUND

Nuclear protein in testis (NUT) carcinoma is a rare tumor associated with NUT rearrangement that can present as poorly differentiated to undifferentiated carcinoma, with or without abrupt squamous differentiation. It is often misdiagnosed as poorly differentiated carcinoma or undifferentiated carcinoma if NUT is not suspected. In this study, we retrospectively analyzed pulmonary NUT carcinoma cases diagnosed with NUT immunohistochemical staining and discuss the differential diagnosis to provide information for this rare and aggressive entity.

METHODS

Cases, diagnosed as "NUT carcinoma" in lung pleura and "metastatic NUT carcinoma from the lung" in lymph nodes were diagnosed between 2017 and 2019 at the Samsung Medical Center (SMC). Clinical features such as age, sex, treatment and follow-up period, and pathological reports were obtained by reviewing patients' electronic medical records.

RESULTS

A total of 10 NUT carcinoma cases were found in the SMC pathology database. Seven patients were men and six were non-smokers. Tumor cells showed various cellular features such as round, squamoid, and spindle. Some cases had initially been misdiagnosed as spindle cell neoplasm, round cell sarcoma, squamous cell carcinoma and small cell carcinoma. All cases showed diffuse strong nuclear expression of NUT immunohistochemical staining, and some were positive for p63 staining and negative for CD56 staining.

CONCLUSIONS

NUT carcinoma is often misdiagnosed because of its various morphologies. It is important to consider NUT as one of the differential diagnoses when encountering lung biopsy with undifferentiated morphology.

KEY POINTS

Due to various morphological features, NUT carcinoma can be misdiagnosed It is important to consider NUT carcinoma when diagnosing a poorly differentiated or undifferentiated tumor.

Advances in the pathogenesis and treatment of nut carcinoma: a narrative review

NUT carcinoma (NC) is a rare, highly invasive and fatal tumor and often misdiagnosed. It typically arises from the mediastinum and midline organs and has complicated pathogenesis and poor outcome. Genetically, its pathogenesis is related to a chromosomal rearrangement involving the NUTM1 gene. In most cases, the main oncoprotein is BRD4-NUT with a translocation between NUTM1 and BRD4 genes, but in a few cases, the oncoprotein is BRD3-NUT, or NSD3-NUT. Studies have shown that the histone hyperacetylation and BRD4 hyperphosphorylation may lead to the activation of cancer circuits. Abnormal production of microRNA, inactivation of tumor suppressor genes and abnormal activation of several signaling pathways are proposed as potential mechanisms underlying the pathogenesis of NC. Currently, there is no consensus on its standard treatment for NC. Extent of surgical resection with negative margins, initial radiotherapy and part of chemotherapy regimens may significantly associated with the improvement of progression-free survival (PFS) rate and overall survival (OS) rate. Some bromodomain and extraterminal inhibitors (BETis) have shown encouraging results in the clinical trials on NC, but delayed drug resistance is still an important issue that needs to be resolved. Histone deacetylase inhibitors are also found to possess the potential in the treatment of NC. Herein, we summarize recent advances in the pathogenesis and treatment of NC.

Nuclear protein in testis midline carcinoma in a Turkish boy: a case report

Background

Nuclear protein in testis (NUT) midline carcinoma (NMC) is an undifferentiated carcinoma, usually localized to the midline and presenting a translocation in the gene for bromodomain containing protein 4. Here, we report a rare case of NMC in an 8-year-old Turkish boy.

Case report

There were masses in the lung, liver, and iliac wing representing metastases. Abdominal lymph node sampling revealed epithelial tumor infiltration with cellular pleomorphism. Immunohistochemistry was strongly positive for cytokeratin and epithelial membrane antigen protein. Because of undifferentiated carcinoma morphology, the tumor was considered to be a NMC. Immunoreactivity with antibodies to NUT and the presence of NUT clarified by fluorescence in situ hybridization (FISH) supported the diagnosis. Despite initial response to chemotherapy, the patient died 7 months after the diagnosis.

Conclusions

Immunoreactivity for NUT antibodies along with a dual-color FISH and karyotype analysis was suggestive for diagnosis of NMC. In differential diagnosis of undifferentiated carcinomas that occur particularly at midline localization, NMC should be considered.

NUT Carcinoma in a Patient with Unusually Long Survival and False Negative FISH Results

Nuclear protein in testis (NUT) carcinoma is a rare and highly aggressive epithelial malignancy defined by rearrangement of the NUTM1 gene on chromosome 15q14. Histologically, NUT carcinoma is an undifferentiated carcinoma formed by sheets and nests of primitive and monotonous "round blue cells" with foci of abrupt keratinization in a subset. NUT carcinoma runs a fulminant clinical course and is almost always quickly lethal, with a median overall survival of only 6.7 months. There is no consensus regarding treatment for this disease, and most patients respond poorly to conventional chemotherapy and radiation. We report a case of NUT carcinoma in an African-American man who initially presented in 2009 with a tracheal mass at age 28. Although fluorescence in situ hybridization (FISH) assays for NUTM1 and BRD4 rearrangements were negative, he was diagnosed based on diffusely positive NUT immunostaining and BRD4-NUTM1 on RNA sequencing. Since his initial presentation, he has undergone multiple surgical procedures and radiation therapy. His tumor has recurred twice, but he has survived for 129 months and is currently alive without disease. Long-term survival of patients with NUT carcinoma is incredibly unusual, especially in patients with tumors that exhibit a BRD4 rearrangement. False negative FISH is a pitfall in diagnosing NUT carcinoma; NUT immunostaining and RNA sequencing are more sensitive diagnostic methods.

Imaging spectrum of NUT carcinomas

Nuclear protein of the testis (NUT) carcinoma (NC) (formerly known as NUT midline carcinoma) is an aggressive pleomorphic squamous cell carcinoma with a dismal prognosis. Primary NC tumors are commonly located in the chest or head and neck regions. Imaging plays an indispensable role in the staging, management, treatment response assessment, and surveillance of NC. Primary pulmonary NC usually presents as a large mass with lymphadenopathy and pleural involvement. Primary head and neck NC presents as a large expansile necrotic mass in the sinonasal region with locoregional destruction and occasional cervical lymph node involvement. These imaging features are relatively non-specific but are consistent among patients. Currently, there are no standardized guidelines for the treatment of NC. Because of its rarity, paucity of reports in the medical literature, and the lack of awareness among radiologists, NUT carcinoma (NC) has been largely underdiagnosed and misdiagnosed. Clinical aggressive features and pleomorphic/undifferentiated squamous cell carcinoma should prompt genetic evaluation for NUT translocation to diagnose NC. In this article, we discuss NC's clinicopathologic and imaging features and treatment options, including emerging new treatments.

Bromodomain-Containing Protein BRD4 Is Hyperphosphorylated in Mitosis

The epigenetic reader BRD4 binds acetylated histones and plays a central role in controlling cellular gene transcription and proliferation. Dysregulation of BRD4's activity has been implicated in the pathogenesis of a wide variety of cancers. While blocking BRD4 interaction with acetylated histones using BET inhibitors (BETis) has been tested in clinical trials, many cancers have acquired BETi resistance. However, the underlying mechanisms are poorly understood and BETi resistance remains a pressing clinical problem. We previously showed that BRD4 phosphorylation supports stronger chromatin binding and target oncogene expression. In this study, we discovered that BRD4 is hyperphosphorylated by CDK1 during mitosis and determined the major CDK1 phosphorylation sites in BRD4. Using CRISPR/Cas9 gene editing, we replaced endogenous BRD4 with a non-phosphorylatable mutant and demonstrated that CDK1-mediated BRD4 phosphorylation contributes to BETi resistance. CDK1 over-activation frequently observed in cancers has the potential to cause aberrant BRD4 hyperphosphorylation persisting outside of mitosis to strengthen its target gene binding and confer BETi resistance. We found that dual CDK1 and BET inhibition generates a synergistic effect in killing BETi-resistant cancer cells. Our study therefore suggests that CDK1 inhibition can be employed to overcome tumor BETi resistance and improve treatments for BRD4-associated cancers.

Combined Targeting of the BRD4-NUT-p300 Axis in NUT Midline Carcinoma by Dual Selective Bromodomain Inhibitor, NEO2734

NUT midline carcinoma (NMC) is a rare, aggressive subtype of squamous carcinoma that is driven by the BRD4-NUT fusion oncoprotein. BRD4, a BET protein, binds to chromatin through its two bromodomains, and NUT recruits the p300 histone acetyltransferse (HAT) to activate transcription of oncogenic target genes. BET-selective bromodomain inhibitors have demonstrated on-target activity in patients with NMC, but with limited efficacy. P300, like BRD4, contains a bromodomain. We show that combining selective p300/CBP and BET bromodomain inhibitors, GNE-781 and OTX015, respectively, induces cooperative depletion of MYC and synergistic inhibition of NMC growth. Treatment of NMC cells with the novel dual p300/CBP and BET bromodomain-selective inhibitor, NEO2734, potently inhibits growth and induces differentiation of NMC cells in vitro; findings that correspond with potentiated transcriptional effects from combined BET and p300 bromodomain inhibition. In three disseminated NMC xenograft models, NEO2734 provided greater growth inhibition, with tumor regression and significant survival benefit seen in two of three models, compared with a lead clinical BET inhibitor or "standard" chemotherapy. Our findings provide a strong rationale for clinical study of NEO2734 in patients with NMC. Moreover, the synergistic inhibition of NMC growth by CBP/p300 and BET bromodomain inhibition lays the groundwork for greater mechanistic understanding of the interplay between p300 and BRD4-NUT that drives this cancer.

Emerging entities in NUTM1-rearranged neoplasms

Structural alterations of NUTM1 were originally thought to be restricted to poorly differentiated carcinomas with variable squamous differentiation originating in the midline organs of children and adolescents. Termed NUT carcinomas (NCs), they were defined by a t(15;19) chromosomal rearrangement that was found to result in a BRD4-NUTM1 gene fusion. However, the use of DNA and RNA-based next-generation sequencing has recently revealed a multitude of new NUTM1 fusion partners in a diverse array of neoplasms including sarcoma-like tumors, poromas, and acute lymphoblastic leukemias (ALLs) that we propose to call NUTM1-rearranged neoplasms (NRNs). Intriguingly, the nosology of NRNs often correlates with the functional classification of the fusion partner, suggesting different oncogenic mechanisms within each NRN division. Indeed, whereas NCs are characterized by their aggressiveness and intransigence to standard therapeutic measures, the more positive clinical outcomes seen in some sarcoma and ALL NRNs may reflect these mechanistic differences. Here we provide a broad overview of the molecular, nosological, and clinical features in these newly discovered neoplastic entities. We describe how aberrant expression of NUTM1 due to fusion with an N-terminal DNA/chromatin-binding protein can generate a potentially powerful chromatin modifier that can give rise to oncogenic transformation in numerous cellular contexts. We also conclude that classification, clinical behavior, and therapeutic options may be best defined by the NUTM1 fusion partner rather than by tumor morphology or immunohistochemical profile.

Salivary Gland NUT Carcinoma with Prolonged Survival in Children: Case Illustration and Systematic Review of Literature

NUT (midline) carcinoma is a rare, highly aggressive, poorly differentiated carcinoma that characteristically harbors a rearrangement of the NUTM1 gene. Most of these tumors occur in adolescents and young adults, arise from the midline structures of the thorax, head, and neck, and are associated with extremely poor outcomes. Rare cases originating from salivary glands have been reported with clinicopathologic features comparable to NUT carcinoma of other sites. Outcome studies regarding this subgroup are currently lacking. We report a case of NUT carcinoma arising in a submandibular gland of a 12-year-old boy. Diagnosis was confirmed by fluorescence in situ hybridization demonstrating fusion of the BRD4 (19p13.12) and NUTM1 (15q14) gene loci. A systematic review of all previously reported salivary gland NUT carcinomas (n = 15) showed exclusive occurrence of pediatric cases (n = 6) in males compared to adult patients (n = 9, male: female = 1:2; p < 0.05). The median survival was 24 and 4 months for pediatric and adult patients, respectively (95% confidence interval was 8-24 and 1-7 months, respectively; p < 0.01). The 1-year overall survival was 67% for pediatric and 11% for adult patients. Among all NUT carcinomas, pediatric salivary gland tumors may represent a distinct clinical subset associated with male predilection and comparatively prolonged survival.

Inhibitors of DNA Methylation and Histone Deacetylation as Epigenetically Active Drugs for Anticancer Therapy

Gene expression is regulated and tightly controlled by epigenetic mechanisms. Alterations of these mechanisms are frequently observed in various diseases, particularly, in various types of cancer. Malignant transformation is caused by the impairment of the mechanisms of cell differentiation and cell cycle control associated with epigenetic changes. Altered patterns of epigenetic modification associated with malignancies can potentially be reversed by some agents that act on the key proteins responsible for DNA/histone modification and chromatin remodelling. Examples of such substances include the inhibitors of DNA methyltransferases or histone deacetylase. During the recent years, a number of such substances have been evaluated as potential therapeutic agents against certain types of cancer in preclinical and clinical studies, and some of them have been approved for treatment of hematological cancers. Application of epidrugs for therapy of solid tumors remains, however, more challenging. In this review, we summarize the current knowledge on the most studied mechanisms of epigenetic modification and the available epigenetically active drugs.

Prevalence of NUT carcinoma in head and neck: Analysis of 362 cases with literature review

BACKGROUND

Nuclear protein in testis (NUT) carcinoma is a poorly differentiated carcinoma defined by the presence of NUT gene rearrangement. In the head and neck, the true prevalence of NUT carcinoma is unknown.

METHODS

We retrospectively investigated NUT expression with clinicopathologic features in 362 patients of poorly differentiated or undifferentiated carcinomas in the head and neck, and reviewed the literature reports.

RESULTS

Four (4/362, 1.1%) cases showed strong nuclear expression for NUT-specific monoclonal antibody, and all these tumors were in the sinonasal tract (4/40, 10%). The clinical outcome and histology were diverse unlike previously described. Although previous studies reported different frequency results according to study subjects, frequencies in sinonasal tract are relatively constant (10/80, 12.5%).

CONCLUSIONS

This is the largest study on the prevalence of NUT carcinoma in head and neck areas. It is important to include in the differential diagnosis of poorly differentiated carcinoma, particularly in the sinonasal tract.