Hepatocellular carcinoma (HCC) is one of the most lethal malignant tumors worldwide. Brahma-related gene 1 (BRG1), as a catalytic ATPase, is a major regulator of gene expression and is known to mutate and overexpress in HCC. The purpose of this study was to investigate the mechanism of action of BRG1 in HCC cells. In our study, BRG1 was silenced or overexpressed in human HCC cell lines. Transwell and wound healing assays were used to analyze cell invasiveness and migration. Mitochondrial membrane potential (MMP) and mitochondrial permeability transition pore (mPTP) detection were used to evaluate mitochondrial function in HCC cells. Colony formation and cell apoptosis assays were used to evaluate the effect of BRG1/TOMM40/ATP5A1 on HCC cell proliferation and apoptosis/death. Immunocytochemistry (ICC), immunofluorescence (IF) staining and western blot analysis were used to determine the effect of BRG1 on TOMM40, ATP5A1 pathway in HCC cells. As a result, knockdown of BRG1 significantly inhibited cell proliferation and invasion, promoted apoptosis in HCC cells, whereas BRG1 overexpression reversed the above effects. Overexpression of BRG1 can up-regulate MMP level, inhibit mPTP opening and activate TOMM40, ATP5A1 expression. Our results suggest that BRG1, as an oncogene, promotes HCC progression by regulating TOMM40 affecting mitochondrial function and ATP5A1 synthesis. Targeting BRG1 may represent a new and effective way to prevent HCC development.

BACKGROUND: SMARCA4, as one of the subunits of the SWI/SNF chromatin remodeling complex, drives SMARCA4-deficient tumors. Gastric SMARCA4-deficient tumors may include gastric SMARCA4-deficient carcinoma and gastric SMARCA4-deficient undifferentiated tumor (SMARCA4-UT). Gastric SMARCA4-UT is rare and challenging to diagnose in clinical practice. The present report aims to provide insight into the clinicopathological characteristics and genetic alterations of gastric SMARCA4-UTs.
RESULTS: We retrospectively reported four rare cases of gastric SMARCA4-UTs. All four cases were male, aged between 61 and 82 years. These tumors presented as ulcerated and transmural masses with infiltration, staged as TNM IV in cases 1, 2 and 4, and TNM IIIA in case 3. Pathologically, four cases presented solid architecture with undifferentiated morphology. Cases 2 and 3 showed focal necrosis and focal rhabdoid morphology. Immunohistochemical staining showed negative expression of epithelial markers and deficient expression of SMARCA4. Furthermore, positivity for Syn (cases 1, 2 and 3) and SALL4 (cases 1 and 2) were observed. Mutant p53 expression occurred in four cases, resulting in strong and diffuse staining of p53 expression in cases 1, 2 and 4, and complete loss in case 3. The Ki67 proliferative index exceeded 80%. 25% (1/4, case 4) of cases had mismatch repair deficiency (dMMR). Two available cases (cases 1 and 3) were detected with SMRACA4 gene alterations. The response to neoadjuvant therapy was ineffective in case 1.
CONCLUSIONS: Gastric SMARCA4-UT is a rare entity of gastric cancer with a poor prognosis, predominantly occurs in male patients. The tumors are typically diagnosed at advanced stages and shows a solid architecture with undifferentiated morphology. Negative expression of epithelial markers and complete loss of SMARCA4 immunoexpression are emerging as a useful diagnostic tool for rare gastric SMARCA4-UTs.

In mammal, the myocardium loss cannot be recovered spontaneously due to the negligible proliferation ability of mature mammalian cardiomyocyte. However, accumulated evidence has shown that terminally differentiated mammalian cardiomyocyte also has proliferation potency, which can be mediated by several mechanisms. Here, we reported that circNCX1, the most abundant circular RNA in mammalian hearts, can affect the proliferation of murine cardiomyocytes. The level of circNCX1 is significantly elevated during heart development. Forced expression of circNCX1 inhibits cardiomyocyte proliferation, while silencing of endogenous circNCX1 in cardiomyocyte shows reversed effect in vitro. Mechanistically, circNCX1 functions via negatively regulating transcription activator BRG1. It bridges BRG1 and FBXW7 to enhance the ubiquitination and degradation of BRG1, decreasing the expression of BMP10 to lead cell cycle arrest. In summary, our study first revealed that circNCX1 is a modulator of cardiomyocyte proliferation.

UNASSIGNED: Thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT) is a distinct clinicopathological entity with an aggressive clinical course. Additionally, SMARCA4/BRG1 deficiency can be observed in a few patients with non-small cell lung cancer (NSCLC). We aimed to compare the clinicopathological, immunohistochemical and prognostic features of SMARCA4-deficient NSCLC (SMARCA4-dNSCLC) with those of thoracic SMARCA4-UT.
UNASSIGNED: Patients with BRG1-deficient tumors in the lung or thorax were enrolled in the study from the Department of Pathology of West China Hospital, Sichuan University, from January 2014 to June 2022. We retrospectively collected the clinicopathological and immunohistochemical features and outcomes of these patients.
UNASSIGNED: Seventy-two patients had tumors in the lung or thorax with BRG1-deficient expression, including 52 patients with SMARCA4-dNSCLC and 20 patients with thoracic SMARCA4-UT. Among the patients with SMARCA4-dNSCLC, 98.1% were male, 85.7% were smokers, and 79.5% (35/44) had tumor-node-metas-tasis (TNM) III-IV tumors. Among the patients with thoracic SMARCA4-UT, all were males who smoked, and 93.75% (15/16) had TNM III-IV tumors. Pure solid architecture and necrosis were the predominant pathological features. Rhabdoid morphology was observed in some SMARCA4-dNSCLCs (10/52, 19.2%) and thoracic SMARCA4-UTs (11/20, 55%). In most patients with thoracic SMARCA4-UT, the tumors exhibited scattered weak expression or negative expression of epithelial markers, and positive expression of CD34 and Syn. Overall survival (OS) and progression-free survival (PFS) were not significantly different between patients with SMARCA4-dNSCLC and patients with thoracic SMARCA4-UT (p = 0.63 and p = 0.20, respectively).
UNASSIGNED: Thoracic SMARCA4-DTs include SMARCA4-dNSCLC and thoracic SMARCA4-UT. Both have overlapping clinicopathological features and poor prognosis. We hypothesize that thoracic SMARCA4-UT may be the undifferentiated or dedifferentiated form of SMARCA4-dNSCLC. However, further studies with larger cohorts and longer follow-up periods are needed.

Strong evidence has indicated that upregulation of chemokine (CC motif) ligand-2 (CCL2) expression and the presence of an inflammatory tumor microenvironment significantly contribute to the migratory and invasive properties of oral squamous cell carcinoma, specifically oral tongue squamous cell carcinoma (OTSCC). However, the precise epigenetic mechanism responsible for enhanced CCL2 expression in response to the inflammatory mediator tumor necrosis factor alpha (TNF-α) in OTSCC remains inadequately elucidated. We have demonstrated that the production of CCL2 can be induced by TNF-α, and this induction is mediated by the chromatin remodel protein BRG1. Through the use of a chromatin immunoprecipitation (ChIP) assay, we have found that BRG1 was involved in the recruitment of acetylated histones H3 and H4 at the CCL2 promoter, thereby activating TNF-α-induced CCL2 transcription. Furthermore, we have observed that recruitment of NF-κB p65 to the CCL2 promoter was increased following BRG1 overexpression and decreased after BRG1 knockdown in OTSCC cells. Our Re-ChIP assay has shown that BRG1 knockdown completely inhibits the recruitment of both acetylated histone H3 or H4 and NF-κB to the CCL2 promoter. In summary, the findings of our study demonstrate that BRG1 plays a significant role in mediating the production of CCL2 in OTSCC cells in response to TNF-α stimulation. This process involves the cooperative action of acetylated histone and NF-κB recruitment to the CCL2 promoter site. Our data suggest that BRG1 serves as a critical epigenetic mediator in the regulation of TNF-α-induced CCL2 transcription in OTSCC cells.

Thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT) is a recently recognized distinct clinicopathological entity according to the fifth edition of the 2021 World Health Organization Classification (WHO) for thoracic tumors. Thoracic SMARCA4-UTs are diagnostically challenging to diagnose, especially on small biopsies.
We identified 35 thoracic SMARCA4-UTs from the Department of Pathology of West China Hospital, Sichuan University, between January 2017 and December 2022. In the present study, we summarized the clinicopathological features, prognostic significance and immunotherapy efficacy of thoracic SMARCA4-UTs.
All 35 patients were male, and 88.6 % were smokers. The left upper lobe (25.7 %) and mediastinum (20.0 %) were the most affected sites. 17.1 % of the patients received surgical treatment. 30.4 % of the patients were stage III, and 69.6 % were stage IV. Solid architecture (100 %), rhabdoid morphology (51.4 %) and necrosis (42.9 %) were the common histological features. Immunohistochemical staining revealed CD34 and synaptophysin positivity in most patients (76.9 % and 65.2 %, respectively). Patients had unfavorable outcomes. Patients who received immunotherapy had better OS and PFS than those who did not (p = 0.007 and p = 0.02, respectively). Five patients were evaluated for immunotherapy efficacy, and four of those patients were negative expression of PD-L1. Cases 1-4 presented TIL counts ranging from 20 to 1000/HPF. Case 5 presented TIL counts of 5-10/HPF. Mutations in SMARCA4 were confirmed in cases 4 and 5, and the TMB was 5.98 and 5.03 mutations/Mb, respectively. Case 1 achieved a CR, cases 2-4 achieved a PR, and case 5 had a PD. Five patients who received immunotherapy were all alive, with OS ranging from 10.7 to 33.6 months.
Thoracic SMARCA4-UTs exhibited an aggressive clinical course, presented solid architecture with or without necrosis and/or rhabdoid morphology, and frequently expressed CD34 and synaptophysin. Some thoracic SMARCA4-UTs appear to be associated with responsiveness to immunotherapy, suggesting the need for validation in larger series.

The epigenetic modification levels of donor cells directly affect the developmental potential of somatic cell nuclear transfer (SCNT) embryos. BRG1, as an epigenetic modifying enzyme, has not yet been studied in donor cells and SCNT embryos. In this study, BRG1 was overexpressed in porcine fetal fibroblasts (PFFs), its effect on chromatin openness and gene transcription was examined, subsequently, the development potential of porcine SCNT embryos was investigated. The results showed that compared with the control group, the percentage of G1 phase cells was significantly increased (32.3 % ± 0.87 vs 25.7 % ± 0.81, P < 0.05) in the experimental group. The qRT-PCR results showed that the expression of H3K9me3-related genes was significantly decreased (P < 0.05), HAT1 was significantly increased (P < 0.05). Assay of Transposase Accessible Chromatin sequencing (ATAC-seq) results revealed that SMARCA4、NANOG、SOX2、MAP2K6 and HIF1A loci had more open chromatin peaks in the experimental group. The RNA-seq results showed that the upregulated genes were mainly enriched in PI3K/AKT and WNT signaling pathways, and the downregulated genes were largely focused on disease development. Interestingly, the developmental rate of porcine SCNT embryos was improved (27.33 % ± 1.40 vs 17.83 % ± 2.02, P < 0.05), the expression of zygotic gene activation-related genes in 4-cell embryos, and embryonic development-related genes in blastocysts was significantly upregulated in the experimental group (P < 0.05). These results suggest that overexpression of BRG1 in donor cells is benefit for the developmental potential of porcine SCNT embryos.

Methionine (Met) functions as a key stimulator on the mTOR signaling pathway and milk synthesis, but the molecular mechanism remains incompletely understood. We investigated the regulatory roles of BRCC36 in Met-stimulated milk lipid and protein synthesis, cell proliferation, and the mTOR signaling pathway. Knockdown of BRCC36 promoted milk lipid and protein synthesis in HC11 cells as well as cell proliferation by increasing the levels of mTOR gene transcription and protein phosphorylation. Conversely, the gene activation of BRCC36 had opposite effects. Furthermore, BRCC36 gene activation completely blocked Met stimulation on the BRG1 protein level and mTOR mRNA level and protein phosphorylation. BRCC36 bound to BRG1, and BRCC36 and BRG1 bound to the same region on the mTOR promoter. BRCC36 inhibited the BRG1 protein level and the binding of BRG1 to the mTOR promoter. Met decreased the BRCC36 protein level, and this effect was significantly attenuated by MG132 but not affected by cycloheximide or chloroquine. We further showed that Met increased BRCC36 ubiquitination degradation. Our findings reveal that Met promotes milk lipid and protein synthesis in MECs through the BRCC36-BRG1-mTOR signaling axis.

Cardiovascular diseases (CVDs) still maintain high morbidity and mortality globally. Helicases, a unique class of enzymes, are extensively implicated in the processes of nucleic acid (NA) metabolism across various organisms. They play a pivotal role in gene expression, inflammatory response, lipid metabolism, and so forth. However, abnormal helicase expression has been associated with immune response, cancer, and intellectual disability in humans. Superfamily II (SFII) is one of the largest and most diverse of the helicase superfamilies. Increasing evidence has implicated SFⅡ helicases in the pathogenesis of multiple CVDs. In this review, we comprehensively review the regulation mechanism of SFⅡ helicases in CVDs including atherosclerosis, myocardial infarction, cardiomyopathies, and heart failure, which will contribute to the investigation of ideal therapeutic targets for CVDs.

UNASSIGNED: Gastrointestinal neuroendocrine carcinoma (GI NEC) is a rare but highly malignant neoplasm with an aggressive clinical course. SMARCA4 is one of the subunits of the SWI/SNF chromatin remodeling complex. SMARCA4 deficiency can occur rarely in subsets of NECs. Reports of the clinicopathological features of GI NECs with SMARCA4 deficiency are limited.
UNASSIGNED: In this study, we retrospectively reported two rare cases of GI NEC with SMARCA4 deficiency and described the clinicopathological, radiographic and histopathological features.
UNASSIGNED: Case 1 was a 43-year-old male with a stage cT3NxM1, IV tumor. Case 2 was a 64-year-old female with a stage cT4aN1M0, IIIA tumor. Both tumors presented as ulcerated masses with infiltration. Pathological examination indicated a solid architecture with poorly differentiated morphology, and complete loss of SMARCA4 (BRG1) was found. Immunohistochemical staining showed positivity for Syn, CgA and CD56. The Ki-67 index was 90% and 70%, respectively. None of the cases had mismatch repair (MMR) deficiency. Case 1 received treatment with chemotherapy and anti-PD-1 immunotherapy. He did not respond to treatment, and died 9 months later. Case 2 received neoadjuvant chemotherapy before surgical treatment, and the tumor showed TRG3 in response to neoadjuvant chemotherapy, chemotherapy and anti-PD-1 immunotherapy were continued after surgical resection. There was no evidence of disease for 10 months.
UNASSIGNED: GI NEC with SMARCA4 deficiency is a rare entity of gastric NEC. SMARCA4 may be a promising targetable and prognostic biomarker. BRG1 immunohistochemical staining could be performed for GI NECs. Further studies with a larger cohort will be needed.