ABCC2 brush-border expression predicts outcome in papillary renal cell carcinoma: a multi-institutional study of 254 cases.

AIMS: Papillary renal cell carcinoma (PRCC) histologic subtyping is no longer recommended in the 2022 WHO classification. Currently, WHO/ISUP nucleolar grade is the only accepted prognostic histologic parameter for PRCC. ABCC2, a renal drug transporter, has been shown to significantly predict outcomes in PRCC. In this study we evaluated the prognostic significance of ABCC2 IHC staining patterns in a large, multi-institutional PRCC cohort and assessed the association of these patterns with ABCC2 mRNA expression. METHODS AND RESULTS: We assessed 254 PRCCs for ABCC2 IHC reactivity patterns that were stratified into negative, cytoplasmic, brush-border <50%, and brush-border ≥50%. RNA in situ hybridization (ISH) was used to determine the transcript level of each group. Survival analysis was performed with SPSS and GraphPad software. RNA-ISH showed that the ABCC2 group with any brush-border staining was associated with a significant increase in the transcript level, when compared to the negative/cytoplasmic group (P = 0.034). Both ABCC2 groups with brush-border <50% (P = 0.024) and brush-border ≥50% (P < 0.001) were also associated with worse disease-free survival (DFS) in univariate analysis. Multivariate analysis showed that only ABCC2 IHC brush-border (<50% and ≥50%) reactivity groups (P = 0.037 and P = 0.003, respectively), and high-stage disease (P < 0.001) had a DFS of prognostic significance. In addition, ABCC2 brush-border showed significantly worse DFS in pT1a (P = 0.014), pT1 (P = 0.013), ≤4 cm tumour (P = 0.041) and high stage (P = 0.014) groups, while a similar analysis with high WHO/ISUP grade in these groups was not significant. CONCLUSION: ABCC2 IHC brush-border expression in PRCC correlates with significantly higher gene expression and also independently predicts survival outcomes.

Aberrant phase separation and nucleolar dysfunction in rare genetic diseases.

Thousands of genetic variants in protein-coding genes have been linked to disease. However, the functional impact of most variants is unknown as they occur within intrinsically disordered protein regions that have poorly defined functions1-3. Intrinsically disordered regions can mediate phase separation and the formation of biomolecular condensates, such as the nucleolus4,5. This suggests that mutations in disordered proteins may alter condensate properties and function6-8. Here we show that a subset of disease-associated variants in disordered regions alter phase separation, cause mispartitioning into the nucleolus and disrupt nucleolar function. We discover de novo frameshift variants in HMGB1 that cause brachyphalangy, polydactyly and tibial aplasia syndrome, a rare complex malformation syndrome. The frameshifts replace the intrinsically disordered acidic tail of HMGB1 with an arginine-rich basic tail. The mutant tail alters HMGB1 phase separation, enhances its partitioning into the nucleolus and causes nucleolar dysfunction. We built a catalogue of more than 200,000 variants in disordered carboxy-terminal tails and identified more than 600 frameshifts that create arginine-rich basic tails in transcription factors and other proteins. For 12 out of the 13 disease-associated variants tested, the mutation enhanced partitioning into the nucleolus, and several variants altered rRNA biogenesis. These data identify the cause of a rare complex syndrome and suggest that a large number of genetic variants may dysregulate nucleoli and other biomolecular condensates in humans.

Targeting the nucleolus as a therapeutic strategy in human disease.

The nucleolus is the site of ribosome biogenesis, one of the most resource-intensive processes in eukaryotic cells. Accordingly, nucleolar morphology and activity are highly responsive to growth signaling and nucleolar insults which are collectively included in the actively evolving concept of nucleolar stress. Importantly, nucleolar alterations are a prominent feature of multiple human pathologies, including cancer and neurodegeneration, as well as being associated with aging. The past decades have seen numerous attempts to isolate compounds targeting different facets of nucleolar activity. We provide an overview of therapeutic opportunities for targeting nucleoli in different pathologies and currently available therapies.

Functional imaging and targeted drug delivery in mice and patient tumors with a cell nucleolus-localizing and tumor-targeting peptide.

Tumor-targeting peptides have profound clinical implications in early detection and delineation of microscopic lesions for surgical resection, and also delivery of therapeutics with reduced systemic toxicity. Here, we demonstrate that a peptide (RS), evolved from a previously reported hepatocellular carcinoma (HCC)-targeting peptide P47, enables improved HCC micrometastasis discrimination and delineation from noncancerous tissues in murine orthotopic mice and patient biopsies, with up to 21-fold contrast. Importantly, RS targets non-small cell lung (NSCLC) and colon cancers in mice and patient biopsies, with higher selectivity for highly proliferative tumor nodules. Moreover, RS localizes to cell nucleoli of HCC, NSCLC, breast, colon and cervical cancer cells and induces nucleolar stress when conjugated with chemotherapeutic Oxaliplatin (OXA) (RS-OXA), demonstrating both cellular and subcellular targeting. RS-delivered OXA elicits significant tumor retardation in orthotopic HCC mice with markedly reduced systemic toxicity compared to OXA alone. Injection of fluorescence-labeled RS enables dynamic visualization of tumor growth in RS-OXA-treated subcutaneous HCC mice. Our study demonstrates that RS targets a spectrum of tumors and localizes to cell nucleolus, thus enabling functional imaging and targeted delivery of OXA in HCC mice, and consequently provides a versatile tool for tumor imaging and targeted therapeutics.

Discovery and Optimization of Pyrrolopyrimidine Derivatives as Selective Disruptors of the Perinucleolar Compartment, a Marker of Tumor Progression toward Metastasis.

The perinucleolar compartment (PNC) is a dynamic subnuclear body found at the periphery of the nucleolus. The PNC is enriched with RNA transcripts and RNA-binding proteins, reflecting different states of genome organization. PNC prevalence positively correlates with cancer progression and metastatic capacity, making it a useful marker for metastatic cancer progression. A high-throughput, high-content assay was developed to identify novel small molecules that selectively reduce PNC prevalence in cancer cells. We identified and further optimized a pyrrolopyrimidine series able to reduce PNC prevalence in PC3M cancer cells at submicromolar concentrations without affecting cell viability. Structure-activity relationship exploration of the structural elements necessary for activity resulted in the discovery of several potent compounds. Analysis of in vitro drug-like properties led to the discovery of the bioavailable analogue, metarrestin, which has shown potent antimetastatic activity with improved survival in rodent models and is currently being evaluated in a first-in-human phase 1 clinical trial.

Metastatic tumors to the pancreas, a 12-year single institution review.

BACKGROUND: Tumors of the pancreas are often primary in nature, but are occasionally proven to be secondary. We report a 12-year review of all pancreatic tumors shown to be metastatic at the University of Colorado. METHOD: The electronic pathology database was searched between 2008 and 2020, for all pancreatic fine-needle aspiration cases at the University of Colorado to identify and review metastatic tumors to the pancreas. Additional data points to include age, sex, radiographic features, and clinical management were analyzed. RESULTS: Our data retrieval identified 39 metastatic tumors to the pancreas comprised of 12 (31%) renal cell carcinomas, 6 (15%) lung carcinomas, and 5 (13%) melanomas with the remainder of tumors originating from a variety of other sites. The most common location of these metastases within the pancreas was the pancreatic head (49%) followed by the body (20%). Eighty-five percentage of cases presented with a single radiographically identified mass. CONCLUSION: While the majority of pancreatic tumors represent primary processes, metastatic tumors to the pancreas represent a possible pitfall. The most common tumors to metastasize to the pancreas in this series were renal cell carcinoma, lung carcinoma, and melanoma. General awareness of the most frequent tumors to metastasize to the pancreas is practical when faced with a pancreatic lesion that could represent a metastasis, or in the absence of clinical history.

CRYßB2 enhances tumorigenesis through upregulation of nucleolin in triple negative breast cancer.

Expression of ß-crystallin B2 (CRYßB2) is elevated in African American (AA) breast tumors. The underlying mechanisms of CRYßB2-induced malignancy and the association of CRYßB2 protein expression with survival have not yet been described. Here, we report that the expression of CRYßB2 in breast cancer cells increases stemness, growth, and metastasis. Transcriptomics data revealed that CRYßB2 upregulates genes that are functionally associated with unfolded protein response, oxidative phosphorylation, and DNA repair, while down-regulating genes related to apoptosis. CRYßB2 in tumors promotes de-differentiation, an increase in mesenchymal markers and cancer-associated fibroblasts, and enlargement of nucleoli. Proteome microarrays identified a direct interaction between CRYßB2 and the nucleolar protein, nucleolin. CRYßB2 induces nucleolin, leading to the activation of AKT and EGFR signaling. CRISPR studies revealed a dependency on nucleolin for the pro-tumorigenic effects of CRYßB2. Triple-negative breast cancer (TNBC) xenografts with upregulated CRYßB2 are distinctively sensitive to the nucleolin aptamer, AS-1411. Lastly, in AA patients, higher levels of nucleolar CRYßB2 in primary TNBC correlates with decreased survival. In summary, CRYßB2 is upregulated in breast tumors of AA patients and induces oncogenic alterations consistent with an aggressive cancer phenotype. CRYßB2 increases sensitivity to nucleolin inhibitors and may promote breast cancer disparity.

Manipulation of Cellular Processes via Nucleolus Hijaking in the Course of Viral Infection in Mammals.

Due to their exceptional simplicity of organization, viruses rely on the resources, molecular mechanisms, macromolecular complexes, regulatory pathways, and functional compartments of the host cell for an effective infection process. The nucleolus plays an important role in the process of interaction between the virus and the infected cell. The interactions of viral proteins and nucleic acids with the nucleolus during the infection process are universal phenomena and have been described for almost all taxonomic groups. During infection, proteins of the nucleolus in association with viral components can be directly used for the processes of replication and transcription of viral nucleic acids and the assembly and transport of viral particles. In the course of a viral infection, the usurpation of the nucleolus functions occurs and the usurpation is accompanied by profound changes in ribosome biogenesis. Recent studies have demonstrated that the nucleolus is a multifunctional and dynamic compartment. In addition to the biogenesis of ribosomes, it is involved in regulating the cell cycle and apoptosis, responding to cellular stress, repairing DNA, and transcribing RNA polymerase II-dependent genes. A viral infection can be accompanied by targeted transport of viral proteins to the nucleolus, massive release of resident proteins of the nucleolus into the nucleoplasm and cytoplasm, the movement of non-nucleolar proteins into the nucleolar compartment, and the temporary localization of viral nucleic acids in the nucleolus. The interaction of viral and nucleolar proteins interferes with canonical and non-canonical functions of the nucleolus and results in a change in the physiology of the host cell: cell cycle arrest, intensification or arrest of ribosome biogenesis, induction or inhibition of apoptosis, and the modification of signaling cascades involved in the stress response. The nucleolus is, therefore, an important target during viral infection. In this review, we discuss the functional impact of viral proteins and nucleic acid interaction with the nucleolus during infection.

Early nucleolar responses differentiate mechanisms of cell death induced by oxaliplatin and cisplatin.

Recent reports provide evidence that the platinum chemotherapeutic oxaliplatin causes cell death via ribosome biogenesis stress, while cisplatin causes cell death via the DNA damage response (DDR). Underlying differences in mechanisms that might initiate disparate routes to cell death by these two broadly used platinum compounds have not yet been carefully explored. Additionally, prior studies had demonstrated that cisplatin can also inhibit ribosome biogenesis. Therefore, we sought to directly compare the initial influences of oxaliplatin and cisplatin on nucleolar processes and on the DDR. Using pulse-chase experiments, we found that at equivalent doses, oxaliplatin but not cisplatin significantly inhibited ribosomal RNA (rRNA) synthesis by Pol I, but neither compound affected rRNA processing. Inhibition of rRNA synthesis occurred as early as 90 min after oxaliplatin treatment in A549 cells, concurrent with the initial redistribution of the nucleolar protein nucleophosmin (NPM1). We observed that the nucleolar protein fibrillarin began to redistribute by 6 h after oxaliplatin treatment and formed canonical nucleolar caps by 24 h. In cisplatin-treated cells, DNA damage, as measured by γH2AX immunofluorescence, was more extensive, whereas nucleolar organization was unaffected. Taken together, our results demonstrate that oxaliplatin causes early nucleolar disruption via inhibition of rRNA synthesis accompanied by NPM1 relocalization and subsequently causes extensive nucleolar reorganization, while cisplatin causes early DNA damage without significant nucleolar disruption. These data support a model in which, at clinically relevant doses, cisplatin kills cells via the canonical DDR, and oxaliplatin kills cells via ribosome biogenesis stress, specifically via rapid inhibition of rRNA synthesis.

Inhibiting ß-catenin disables nucleolar functions in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) patients with upregulated Wnt/ß-catenin signaling often have poor clinical prognoses. During pathological examinations of breast cancer sections stained for ß-catenin, we made the serendipitous observation that relative to non-TNBC, specimens from TNBC patients have a greater abundance of nucleoli. There was a remarkable direct relationship between nuclear ß-catenin and greater numbers of nucleoli in TNBC tissues. These surprising observations spurred our investigations to decipher the differential functional relevance of the nucleolus in TNBC versus non-TNBC cells. Comparative nucleolar proteomics revealed that the majority of the nucleolar proteins in TNBC cells were potential targets of ß-catenin signaling. Next, we undertook an analysis of the nucleolar proteome in TNBC cells in response to ß-catenin inhibition. This effort revealed that a vital component of pre-rRNA processing, LAS1 like ribosome biogenesis factor (LAS1L) was significantly decreased in the nucleoli of ß-catenin inhibited TNBC cells. Here we demonstrate that LAS1L protein expression is significantly elevated in TNBC patients, and it functionally is important for mammary tumor growth in xenograft models and enables invasive attributes. Our observations highlight a novel function for ß-catenin in orchestrating nucleolar activity in TNBCs.

Isolation of Nucleoli for Characterization of Nucleolar Contents to Uncover Clues to Metastatic Progression.

Nucleolar isolation is a crucial technique for the study of nucleolar contents and regulation of ribosome biogenesis. Lysed cells are spun through various concentrations of sucrose and magnesium chloride to separate the notoriously dense nucleoli from the rest of the cell. Here we describe isolation of nucleoli from the breast cancer cell line MDA-MB-468. The resulting nucleolar fraction is subjected to immunoblotting to confirm the purity of the nucleolar fraction.

Dactinomycin induces complete remission associated with nucleolar stress response in relapsed/refractory NPM1-mutated AML.

Acute myeloid leukemia (AML) with mutated NPM1 accounts for one-third of newly diagnosed AML. Despite recent advances, treatment of relapsed/refractory NPM1-mutated AML remains challenging, with the majority of patients eventually dying due to disease progression. Moreover, the prognosis is particularly poor in elderly and unfit patients, mainly because they cannot receive intensive treatment. Therefore, alternative treatment strategies are needed. Dactinomycin is a low-cost chemotherapeutic agent, which has been anecdotally reported to induce remission in NPM1-mutated patients, although its mechanism of action remains unclear. Here, we describe the results of a single-center phase 2 pilot study investigating the safety and efficacy of single-agent dactinomycin in relapsed/refractory NPM1-mutated adult AML patients, demonstrating that this drug can induce complete responses and is relatively well tolerated. We also provide evidence that the activity of dactinomycin associates with nucleolar stress both in vitro and in vivo in patients. Finally, we show that low-dose dactinomycin generates more efficient stress response in cells expressing NPM1 mutant compared to wild-type cells, suggesting that NPM1-mutated AML may be more sensitive to nucleolar stress. In conclusion, we establish that dactinomycin is a potential therapeutic alternative in relapsed/refractory NPM1-mutated AML that deserves further investigation in larger clinical studies.

Nucleolar stress in C9orf72 and sporadic ALS spinal motor neurons precedes TDP-43 mislocalization.

Nucleolar stress has been implicated in the pathology and disease pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) from repeat expansions of GGGGCC in C9orf72 (C9-ALS/FTLD) but not in sporadic ALS (SALS). Previously we reported that antisense RNA transcripts are unique in C9-ALS because of their nucleolar localization in spinal motor neurons and correlation with TDP-43 mislocalization, the hallmark proteinopathy of ALS and FTLD. Here we report our further studies of 11 SALS, 11 C9-ALS and 11 control spinal cords. We find that nucleolar stress manifests specifically as shrinkage in nucleoli of C9-ALS spinal motor neurons. Nucleolar size reduction is greatest in similarly sized alpha motor neurons from C9-ALS cases and results are not skewed by the number of surviving neurons from each ALS spinal cord. Surprisingly, nucleolar shrinkage occurs before main pathological hallmarks-TDP-43 mislocalization or antisense RNA foci-appear and this suggest that nucleolar stress can precede pathology in C9-ALS, findings previously identified in C9-FTLD using sense RNA foci and dipeptide repeat proteins as pathological markers. Importantly, these observations are also seen in SALS motor neurons and thus nucleolar stress appears to be a significant and probably upstream problem in sporadic disease.

G protein coupled receptor kinase 5 modifies the nucleolar stress response activated by actinomycin D.

G protein coupled receptor kinase 5 (GRK5) is localized within the nucleus and moderates functions such as DNA transcription, in addition to its localization at the plasma membrane. In this report, we show that GRK5 modifies the nucleolar stress response activated by the DNA polymerase inhibitor, actinomycin D (ActD). We show an increased sensitivity to the apoptotic effects of ActD on cervical HeLa cells and the breast cancer cell line MDA MB 231 with reduced protein expression of GRK5. We also tested two types of breast cancer cells (MDA MB 231 and MCF7 cells) and found that the rate of response to ActD varied between them because they have innate differences in the protein expression of GRK5. We also found that GRK5 phosphorylates nucleophosmin (NPM1) at T199 before and during the early stages of ActD treatment. Phosphorylation at T199 increases the ability of NPM1 to interact with p14ARF in vitro, which may affect the protein expression levels of p14ARF. We found that the expression levels of p14ARF were lower in the cells transfected with the control shRNA, but higher in cells transfected with GRK5 shRNA. Collectively, this suggests that GRK5 modifies the nucleolar stress response associated with ActD.

The Paris System "atypical urothelial cells" category: can the current criteria be improved?

INTRODUCTION: The Paris System (TPS) for reporting urine cytology was developed for standardization of diagnosis focusing on the detection of high-grade urothelial carcinoma (HGUC). Probably the most challenging task for TPS is to provide criteria for the atypical urothelial cell (AUC) category. The TPS criteria for AUC include increased nuclear/cytoplasmic (N/C) ratio (>0.5) and 1 of the 3 minor criteria including nuclear hyperchromasia (NH), coarse chromatin (CC) and irregular nuclear membrane (INM). We evaluated TPS-AUC diagnostic value and investigated whether other morphologic parameters can improve its criteria. MATERIALS AND METHODS: Urine samples with diagnoses of AUC collected during a 6-month period were re-reviewed. Data captured included N/C ratio >0.5, NH, CC, INM, and 2 additional criteria including enlarged nuclear size (ENS) and the presence of nucleolus (N). ENS was considered when the nucleus was 2 times larger than the urothelial cell or 3 times larger than lymphocyte. RESULTS: By applying the TPS-AUC criteria, the rate of atypia diagnosis reduced in comparison to Pre-TPS (9% versus 13%, P = 0.02). Among the AUC minor criteria, NH was the best criterion with the highest interobserver agreement (IOA) and correlation with HGUC (k = 0.342, r = 0.61, P < 0.001) and strong PPV (93.6%). ENS had the highest PPV (95.8%) and, after NH, had the highest IOA and correlation with HGUC (k = 0.29, r = 0.52, P < 0.001). CONCLUSION: TPS improves the diagnostic value of urine cytology, particularly in cases with atypia. ENS is a strong criterion for increasing the diagnostic value of AUC and potentially can improve TPS performance as a minor criterion.

Novel nucleolar localization of clusterin and its associated functions in human oral cancers: An in vitro and in silico analysis.

Clusterin (CLU), a multifunctional chaperonic glycoprotein associated with diverse cellular functions has been shown to act as an oncogene or tumour suppressor gene in different cancers, implying a dual role in tumorigenesis. Here, we investigated the expression of CLU isoforms, their subcellular localization and functional significance in oral cancer cells. Significant downregulation of secretory CLU (sCLU) transcripts was observed in oral cancer cell lines and tumours versus normal cells while the nuclear CLU (nCLU) transcripts were undetectable. We demonstrated for the first time the nucleolar localization of sCLU, its response to different nucleolar stresses and association with cajal bodies post nucleolar stress. Functionally, knockdown of CLU revealed its negative association with ribosome biogenesis implying a possible tumour suppressor like role in oral cancers. Further, loss of sCLU in these cells also resulted in altered nuclear morphology and shrunken tubulin filaments. In addition, the levels of nucleolar Nucleophosmin 1(NPM1) and Fibrillarin, known to regulate nuclear morphology were downregulated indicating a possible role of sCLU in their stabilization. Further, an in silico docking approach to gain insights into the interaction of sCLU with nucleolar proteins NPM1, Fibrillarin, UBF and Nucleolin, revealed the involvement of a conserved region comprising of amino acid residues 140-155 of sCLU ß-chain, specifically via the Phe152 residue in hydrophobic interactions with these client nucleolar proteins indicating a possible stabilizing or regulatory role of sCLU. SIGNIFICANCE OF THE STUDY: This is the first study to demonstrate the nucleolar localization of sCLU and its associated functions in oral cancer cells. Downregulation of sCLU in oral cancer tissues and cell lines, and its negative association with ribogenesis suggest its tumour suppressor like role in oral cancers. The possible role of sCLU in stabilization or regulation of different nucleolar proteins thereby impacting their functions is also implicated.

Nucleolar stress induces a senescence-like phenotype in smooth muscle cells and promotes development of vascular degeneration.

Senescence of smooth muscle cells (SMCs) has a crucial role in the pathogenesis of abdominal aortic aneurysm (AAA), a disease of vascular degeneration. Perturbation of cellular ribosomal DNA (rDNA) transcription triggers nucleolar stress response. Previously we demonstrated that induction of nucleolar stress in SMCs elicited cell cycle arrest via the ataxia-telangiectasia mutated (ATM)/ATM- and Rad3-related (ATR)-p53 axis. However, the specific roles of nucleolar stress in vascular degeneration remain unexplored. In the present study, we demonstrated for the first time that in both human and animal AAA tissues, there were non-coordinated changes in the expression of RNA polymerase I machinery components, including a downregulation of transcription initiation factor-IA (TIF-IA). Genetic deletion of TIF-IA in SMCs in mice (smTIF-IA-/-) caused spontaneous aneurysm-like lesions in the aorta. In vitro, induction of nucleolar stress triggered a non-canonical DNA damage response, leading to p53 phosphorylation and a senescence-like phenotype in SMCs. In human AAA tissues, there was increased nucleolar stress in medial cells, accompanied by localized DNA damage response within the nucleolar compartment. Our data suggest that perturbed rDNA transcription and induction of nucleolar stress contribute to the pathogenesis of AAA. Moreover, smTIF-IA-/- mice may be a novel animal model for studying spontaneous AAA-like vascular degenerations.

Combined expression levels of KDM2A and KDM2B correlate with nucleolar size and prognosis in primary breast carcinomas.

Ribosome biogenesis is a fine-tuned cellular process and its deregulation is linked to cancer progression: tumors characterized by an intense ribosome biogenesis often display a more aggressive behavior. Ribosomal RNA (rRNA) synthesis is controlled at several levels, the higher one being the epigenetic regulation of the condensation of chromatin portions containing rRNA genes. KDM2A and KDM2B (Lysine (K)-specific demethylase 2A / B) are histone demethylases modulating the accessibility of ribosomal genes, thereby regulating their transcription. Both enzymes are able to demethylate lysins at relevant sites (e.g. K4, K36) on histone H3. We previously demonstrated that KDM2B is one of the factors regulating ribosome biogenesis in human breast cancer. In this study we aimed to define the combined contribution of KDM2A and KDM2B to breast cancer outcome. KDM2A and KDM2B mRNA levels, nucleolar area as a marker of ribosome biogenesis, and patients' prognosis were retrospectively assessed in a series of primary breast carcinomas. We observed that tumors characterized by reduced levels of both KDM2A and KDM2B displayed a particularly aggressive clinical behavior and increased nucleolar size. Our results suggest that KDM2A and KDM2B may cooperate in regulating ribosome biogenesis thus influencing the biological behavior and clinical outcome of human breast cancers.

SMARCB1-deficient carcinomas of the head and neck region: a cytopathologic characterization.

INTRODUCTION: SMARCB1 encodes for a component of the SWI/SNF complex and is widely implicated in carcinogenesis. In the head and neck, SMARCB1-deficient carcinomas typically arise in the sinonasal tract but can be found at other sites. EZH2 inhibitors have emerged as potential targeted therapy against SWI/SNF-deficient tumors. We sought to characterize the cytomorphology of head and neck carcinomas with SMARCB1 deficiencies to identify potential candidates for targeted therapy. MATERIALS AND METHODS: Head and neck carcinomas with SMARCB1 mutations were retrospectively identified and confirmed to be SMARCB1-deficient by both molecular (fluorescent in-situ hybridization or next generation sequencing) and immunohistochemical means. Cases with positive cytology were reviewed and their cytologic features cataloged. RESULTS: A total of 19 specimens from 13 patients were reviewed, including 8 specimens from 7 sinonasal carcinomas, 4 specimens from 3 thyroid carcinomas, 3 specimens from 2 skin carcinomas, and 4 specimens from 1 carcinoma of unknown primary origin. High-grade features were common, including mitoses (11 of 19) necrosis (13 of 19) and multinucleation (16 of 19). Tumors showed either dense cytoplasm with distinct cell borders (10 of 19) or delicate cytoplasm with indistinct cell borders (9 of 19). Most tumors showed no distinct epithelial differentiation (12 of 19), while some (7 of 19) showed glandular or signet ring features. A minor cohort demonstrated rhabdoid cells (4 of 19). CONCLUSIONS: Head and neck carcinomas with SMARCB1 deficiencies have a wide array of morphologies and tend to demonstrate high-grade features. Only a minor cohort demonstrate rhabdoid-type cells. Evaluation of SMARCB1 deficiency for potential targeted therapy should not be limited to tumors with rhabdoid morphology.

Nucleolar stress regulates stromal-epithelial transition via NPM1 during decidualization.

Embryo implantation and decidualization are crucial steps during early pregnancy. We recently showed that nucleolar stress is involved in embryo implantation. This study was to explore whether nucleolar stress participates in mouse and human decidualization. Our data demonstrated that a low dose of actinomycin D (ActD) could induce nucleolar stress in stroma cells. Nucleolar stress promotes the stromal-epithelial transition during mouse in vitro decidualization through nucleophosmin1 (NPM1). Under nucleolar stress, Wnt family member 4 (Wnt4), a decidualization marker, is significantly increased, but decidua/trophoblast prolactin-related protein (Dtprp/Prl8a2) expression remains unchanged. For translational significance, we also examined the effects of nucleolar stress on human decidualization. Nucleolar stress stimulated by a low dose of ActD enhances human stromal-epithelial transition during human decidualization, but has no effects on the expression of insulin-like growth factor-binding protein 1 (IGFBP1). Our study indicates that nucleolar stress may promote only the mesenchymal-epithelial transition (MET), but not for all the molecular changes during decidualization.