Differential requirement for RecFOR pathway components in Thermus thermophilus.

Recombinational repair is an important mechanism that allows DNA replication to overcome damaged templates, so the DNA is duplicated timely and correctly. The RecFOR pathway is one of the common ways to load RecA, while the RuvABC complex operates in the resolution of DNA intermediates. We have generated deletions of recO, recR and ruvB genes in Thermus thermophilus, while a recF null mutant could not be obtained. The recO deletion was in all cases accompanied by spontaneous loss of function mutations in addA or addB genes, which encode a helicase-exonuclease also key for recombination. The mutants were moderately affected in viability and chromosome segregation. When we generated these mutations in a Δppol/addAB strain, we observed that the transformation efficiency was maintained at the typical level of Δppol/addAB, which is 100-fold higher than that of the wild type. Most mutants showed increased filamentation phenotypes, especially ruvB, which also had DNA repair defects. These results suggest that in T. thermophilus (i) the components of the RecFOR pathway have differential roles, (ii) there is an epistatic relationship of the AddAB complex over the RecFOR pathway and (iii) that neither of the two pathways or their combination is strictly required for viability although they are necessary for normal DNA repair and chromosome segregation.

ATP-dependent chromatin remodeller brahma related gene 1 promotes keratinocyte migration and modulates cell Signalling during wound healing in human skin.

Skin wound healing is driven by proliferation, migration and differentiation of several cell types that are controlled by the alterations in the gene expression programmes. Brahma Gene 1 (BRG1) (also known as SMARCA4) is a core ATPase in the BRG1 Associated Factors (BAF) ATP-dependent chromatin remodelling complexes that alter DNA-histone interaction in chromatin at the specific gene regulatory elements resulting in increase or decrease of the target gene transcription. Using siRNA mediated suppression of BRG1 during wound healing in a human ex vivo and in vitro (scratch assay) models, we demonstrated that BRG1 is essential for efficient skin wound healing by promoting epidermal keratinocytes migration, but not their proliferation or survival. BRG1 controls changes in the expression of genes associated with gene transcription, response to wounding, cell migration and cell signalling. Altogether, our data revealed that BRG1 play positive role in skin repair by promoting keratinocyte migration and impacting the genes expression programmes associated with cell migration and cellular signalling.

The ARK2N-CK2 complex initiates transcription-coupled repair through enhancing the interaction of CSB with lesion-stalled RNAPII.

Transcription is extremely important for cellular processes but can be hindered by RNA polymerase II (RNAPII) pausing and stalling. Cockayne syndrome protein B (CSB) promotes the progression of paused RNAPII or initiates transcription-coupled nucleotide excision repair (TC-NER) to remove stalled RNAPII. However, the specific mechanism by which CSB initiates TC-NER upon damage remains unclear. In this study, we identified the indispensable role of the ARK2N-CK2 complex in the CSB-mediated initiation of TC-NER. The ARK2N-CK2 complex is recruited to damage sites through CSB and then phosphorylates CSB. Phosphorylation of CSB enhances its binding to stalled RNAPII, prolonging the association of CSB with chromatin and promoting CSA-mediated ubiquitination of stalled RNAPII. Consistent with this finding, Ark2n-/- mice exhibit a phenotype resembling Cockayne syndrome. These findings shed light on the pivotal role of the ARK2N-CK2 complex in governing the fate of RNAPII through CSB, bridging a critical gap necessary for initiating TC-NER.

Oncogenic functions and therapeutic potentials of targeted inhibition of SMARCAL1 in small cell lung cancer.

Small cell lung cancer (SCLC) is a recalcitrant cancer characterized by high frequency loss-of-function mutations in tumor suppressors with a lack of targeted therapy due to absence of high frequency gain-of-function abnormalities in oncogenes. SMARCAL1 is a member of the ATP-dependent chromatin remodeling protein SNF2 family that plays critical roles in DNA damage repair and genome stability maintenance. Here, we showed that SMARCAL1 was overexpressed in SCLC patient samples and was inversely associated with overall survival of the patients. SMARCAL1 was required for SCLC cell proliferation and genome integrity. Mass spectrometry revealed that PAR6B was a downstream SMARCAL1 signal molecule which rescued inhibitory effects caused by silencing of SMARCAL1. By screening of 36 FDA-approved clinically available agents related to DNA damage repair, we found that an aza-anthracenedione, pixantrone, was a potent SMARCAL1 inhibitor which suppressed the expression of SMARCAL1 and PAR6B at protein level. Pixantrone caused DNA damage and exhibited inhibitory effects on SCLC cells in vitro and in a patient-derived xenograft mouse model. These results indicated that SMARCAL1 functions as an oncogene in SCLC, and pixantrone as a SMARCAL1 inhibitor bears therapeutic potentials in this deadly disease.

Comprehensive Analysis of the Expression, Prognosis, and Immune Infiltrates for Chromodomain-Helicase-DNA-Binding Proteins in Breast Tumor.

BACKGROUND: Several recent studies suggest that chromodomain-helicase -DNA-binding domains (CHDs) are linked with cancers. We explored the association between chromodomain-Helicase-DNA-binding domain proteins and breast cancer (BrCa) and introduced potential prognostic markers using various databases. MATERIALS AND METHODS: We analyzed the expression of the CHD family and their prognostic value in BrCa by mining UALCAN, TIMER, and Kaplan-Meier plotter databases. The association of CHD expression and immune infiltrating abundance was studied via the TIMER database. In addition, microRNAs related to the CHD family were identified by using the MirTarBase online database. RESULTS: The present study indicated that compared to normal tissues, BrCa tissues showed increased mRNA levels of CHD3/4/7 but decreased CHD2/5/9 expression. Interestingly, We also found a positive correlation between CHD gene expression and the infiltration of macrophage, neutrophil, and dendritic cells in BrCa, except CHD3/5. The Kaplan-Meier Plotter analysis suggested that high expression levels of CHD1/2/3/4/6/8/9 were significantly related to shorter relapse-free survival (RFS), while higher mRNA expression of CHD1, CHD2, CHD8, and CHD9 was significantly associated with longer overall survival of BrCa patients. The miRNAs of hsa-miR-615-3p and hsa-let-7b-5p were identified as being more correlated with the CHD family. CONCLUSION: The altered expression of some CHD members was significantly related to clinical cancer outcomes, and CHD1/2/8/9 could serve as potential prognostic biomarkers to improve the survival of BrCa patients. However, to evaluate the studied CHD members in detail are needed further investigations including experimental validation.

CHD7 Disorder-Not CHARGE Syndrome-Presenting as Isolated Cochleovestibular Dysfunction.

CHARGE syndrome, characterized by a distinct set of clinical features, has been linked primarily to mutations in the CHD7 gene. Initially defined by specific clinical criteria, including coloboma, heart defects, choanal atresia, delayed growth, and ear anomalies, CHARGE syndrome's diagnostic spectrum has broadened since the identification of CHD7. Variants in this gene exhibit considerable phenotypic variability, leading to the adoption of the term "CHD7 disorder" to encompass a wider range of associated symptoms. Recent research has identified CHD7 variants in individuals with isolated features such as autism spectrum disorder or gonadotropin-releasing hormone deficiency. In this study, we present three cases from two different families exhibiting audiovestibular impairment as the primary manifestation of a CHD7 variant. We discuss the expanding phenotypic variability observed in CHD7-related disorders, highlighting the importance of considering CHD7 in nonsyndromic hearing loss cases, especially when accompanied by inner ear malformations on MRI. Additionally, we underscore the necessity of genetic counseling and comprehensive clinical evaluation for individuals with CHD7 variants to ensure appropriate management of associated health concerns.

Epicardial SMARCA4 deletion exacerbates cardiac injury in myocardial infarction and is related to the inhibition of epicardial epithelial-mesenchymal transition.

The reactivated adult epicardium produces epicardium-derived cells (EPDCs) via epithelial-mesenchymal transition (EMT) to benefit the recovery of the heart after myocardial infarction (MI). SMARCA4 is the core catalytic subunit of the chromatin re-modeling complex, which has the potential to target some reactivated epicardial genes in MI. However, the effects of epicardial SMARCA4 on MI remain uncertain. This study found that SMARCA4 was activated over time in epicardial cells following MI, and some of activated cells belonged to downstream differentiation types of EPDCs. This study used tamoxifen to induce lineage tracing and SMARCA4 deletion from epicardial cells in Wt1-CreER;Smarca4fl/fl;Rosa26-RFP adult mice. Epicardial SMARCA4 deletion reduces the number of epicardial cells in adult mice, which was related to changes in the activation, proliferation, and apoptosis of epicardial cells. Epicardial SMARCA4 deletion reduced collagen deposition and angiogenesis in the infarcted area, exacerbated cardiac injury in MI. The exacerbation of cardiac injury was related to the inhibition of generation and differentiation of EPDCs. The alterations in EPDCs were associated with inhibited transition between E-CAD and N-CAD during the epicardial EMT, coupled with the down-regulation of WT1, SNAIL1, and PDGF signaling. In conclusion, this study suggests that Epicardial SMARCA4 plays a critical role in cardiac injury caused by MI, and its regulatory mechanism is related to epicardial EMT. Epicardial SMARCA4 holds potential as a novel molecular target for treating MI.

Senataxin deficiency disrupts proteostasis through nucleolar ncRNA-driven protein aggregation.

Senataxin is an evolutionarily conserved RNA-DNA helicase involved in DNA repair and transcription termination that is associated with human neurodegenerative disorders. Here, we investigated whether Senataxin loss affects protein homeostasis based on previous work showing R-loop-driven accumulation of DNA damage and protein aggregates in human cells. We find that Senataxin loss results in the accumulation of insoluble proteins, including many factors known to be prone to aggregation in neurodegenerative disorders. These aggregates are located primarily in the nucleolus and are promoted by upregulation of non-coding RNAs expressed from the intergenic spacer region of ribosomal DNA. We also map sites of R-loop accumulation in human cells lacking Senataxin and find higher RNA-DNA hybrids within the ribosomal DNA, peri-centromeric regions, and other intergenic sites but not at annotated protein-coding genes. These findings indicate that Senataxin loss affects the solubility of the proteome through the regulation of transcription-dependent lesions in the nucleus and the nucleolus.

Physical interactions between specifically regulated subpopulations of the MCM and RNR complexes prevent genetic instability.

The helicase MCM and the ribonucleotide reductase RNR are the complexes that provide the substrates (ssDNA templates and dNTPs, respectively) for DNA replication. Here, we demonstrate that MCM interacts physically with RNR and some of its regulators, including the kinase Dun1. These physical interactions encompass small subpopulations of MCM and RNR, are independent of the major subcellular locations of these two complexes, augment in response to DNA damage and, in the case of the Rnr2 and Rnr4 subunits of RNR, depend on Dun1. Partial disruption of the MCM/RNR interactions impairs the release of Rad52 -but not RPA-from the DNA repair centers despite the lesions are repaired, a phenotype that is associated with hypermutagenesis but not with alterations in the levels of dNTPs. These results suggest that a specifically regulated pool of MCM and RNR complexes plays non-canonical roles in genetic stability preventing persistent Rad52 centers and hypermutagenesis.

Acute depletion of BRG1 reveals its primary function as an activator of transcription.

The mammalian SWI/SNF-like BAF complexes play critical roles during animal development and pathological conditions. Previous gene deletion studies and characterization of human gene mutations implicate that the complexes both repress and activate a large number of genes. However, the direct function of the complexes in cells remains largely unclear due to the relatively long-term nature of gene deletion or natural mutation. Here we generate a mouse line by knocking in the auxin-inducible degron tag (AID) to the Smarca4 gene, which encodes BRG1, the essential ATPase subunit of the BAF complexes. We show that the tagged BRG1 can be efficiently depleted by osTIR1 expression and auxin treatment for 6 to 10 h in CD4 + T cells, hepatocytes, and fibroblasts isolated from the knock-in mice. The acute depletion of BRG1 leads to decreases in nascent RNAs and RNA polymerase II binding at a large number of genes, which are positively correlated with the loss of BRG1. Further, these changes are correlated with diminished accessibility at DNase I Hypersensitive Sites (DHSs) and p300 binding. The acute BRG1 depletion results in three major patterns of nucleosome shifts leading to narrower nucleosome spacing surrounding transcription factor motifs and at enhancers and transcription start sites (TSSs), which are correlated with loss of BRG1, decreased chromatin accessibility and decreased nascent RNAs. Acute depletion of BRG1 severely compromises the Trichostatin A (TSA) -induced histone acetylation, suggesting a substantial interplay between the chromatin remodeling activity of BRG1 and histone acetylation. Our data suggest BRG1 mainly plays a direct positive role in chromatin accessibility, RNAPII binding, and nascent RNA production by regulating nucleosome positioning and facilitating transcription factor binding to their target sites.

Critical role of G3BP1 in bovine parainfluenza virus type 3 (BPIV3)-inhibition of stress granules formation and viral replication.

Background: It remains unclear whether BPIV3 infection leads to stress granules formation and whether G3BP1 plays a role in this process and in viral replication. This study aims to clarify the association between BPIV3 and stress granules, explore the effect of G3BP1 on BPIV3 replication, and provide significant insights into the mechanisms by which BPIV3 evades the host's antiviral immunity to support its own survival. Methods: Here, we use Immunofluorescence staining to observe the effect of BPIV3 infection on the assembly of stress granules. Meanwhile, the expression changes of eIF2α and G3BP1 were determined. Overexpression or siRNA silencing of intracellular G3BP1 levels was examined for its regulatory control of BPIV3 replication. Results: We identify that the BPIV3 infection elicited phosphorylation of the eIF2α protein. However, it did not induce the assembly of stress granules; rather, it inhibited the formation of stress granules and downregulated the expression of G3BP1. G3BP1 overexpression facilitated the formation of stress granules within cells and hindered viral replication, while G3BP1 knockdown enhanced BPIV3 expression. Conclusion: This study suggest that G3BP1 plays a crucial role in BPIV3 suppressing stress granule formation and viral replication.

Rare SMARCA4-deficient thoracic tumor: Insights into molecular characterization and optimal therapeutics methods.

INTRODUCTIONS: The 2021 WHO Classification of Thoracic Tumors recognized SMARCA4-deficient undifferentiated thoracic tumors (SMARCA4-dUT) as a distinct entity that shows a striking overlap in demographic and molecular profiles with SMARCA4-deficient non-small lung cancer (SMARCA4-dNSCLC). The implications of SMARCA4 deficiency based on immunohistochemistry remain unclear. We aimed to investigate molecular characteristics of SMARCA4-deficient thoracic tumors (SDTT) and explore optimal therapeutics. METHODS: From June.15, 2018, to Nov.15, 2023, a large cohort including patients diagnosed with SMARCA4-deficient (N = 196) and SMARCA4-intact (N = 438) thoracic tumors confirmed by immunohistochemistry at SYSUCC were screened. Clinicopathologic and molecular characteristics were identified and compared. External SRRSH cohort (N = 34) was combined into a pooled cohort to compare clinical outcome of first-line therapy efficacy. RESULTS: SDTT is male predominance with smoking history, high tumor burden, and adrenal metastases. The relationship between SMARCA4 mutation and protein expression is not completely parallel. The majority of SMARCA4-deficient patients harbor truncating (Class-I) SMARCA4 mutations, whereas class-II alterations and wild-type also exist. Compared with SMARCA4-intact thoracic tumors, patients with SDTT displayed a higher tumor mutation burden (TMB) and associated with a shorter median OS (16.8 months vs. Not reached; P < 0.001). Notably, SMARCA4 protein deficiency, rather than genetic mutations, played a decisive role in these differences. SDTT is generally resistant to chemotherapy, while sensitive to chemoimmunotherapy (median PFS: 7.5 vs. 3.5 months, P < 0.001). In particular, patients with SMARCA4 deficient thoracic tumors treated with paclitaxel-based chemoimmunotherapy achieved a longer median PFS than those with pemetrexed-based chemoimmunotherapy (10.0 vs. 7.3 months, P = 0.028). CONCLUSIONS: SMARCA4 protein deficiency, rather than genetic mutations, played a decisive role in its characteristics of higher TMB and poor prognosis. Chemoimmunotherapy serves as the optimal option in the current treatment regimen. Paclitaxel-based chemoimmunotherapy performed better than those with pemetrexed-based chemoimmunotherapy.

PARP2 promotes Break Induced Replication-mediated telomere fragility in response to replication stress.

PARP2 is a DNA-dependent ADP-ribosyl transferase (ARTs) enzyme with Poly(ADP-ribosyl)ation activity that is triggered by DNA breaks. It plays a role in the Base Excision Repair pathway, where it has overlapping functions with PARP1. However, additional roles for PARP2 have emerged in the response of cells to replication stress. In this study, we demonstrate that PARP2 promotes replication stress-induced telomere fragility and prevents telomere loss following chronic induction of oxidative DNA lesions and BLM helicase depletion. Telomere fragility results from the activity of the break-induced replication pathway (BIR). During this process, PARP2 promotes DNA end resection, strand invasion and BIR-dependent mitotic DNA synthesis by orchestrating POLD3 recruitment and activity. Our study has identified a role for PARP2 in the response to replication stress. This finding may lead to the development of therapeutic approaches that target DNA-dependent ART enzymes, particularly in cancer cells with high levels of replication stress.

Sequential requirements for distinct Polθ domains during theta-mediated end joining.

DNA polymerase θ (Polθ) plays a central role in a DNA double-strand break repair pathway termed theta-mediated end joining (TMEJ). TMEJ functions by pairing short-sequence "microhomologies" (MHs) in single-stranded DNA at each end of a break and subsequently initiating DNA synthesis. It is not known how the Polθ helicase domain (HD) and polymerase domain (PD) operate to bring together MHs and facilitate repair. To resolve these transient processes in real time, we utilized in vitro single-molecule FRET approaches and biochemical analyses. We find that the Polθ-HD mediates the initial capture of two ssDNA strands, bringing them in close proximity. The Polθ-PD binds and stabilizes pre-annealed MHs to form a synaptic complex (SC) and initiate repair synthesis. Individual synthesis reactions show that Polθ is inherently non-processive, accounting for complex mutational patterns during TMEJ. Binding of Polθ-PD to stem-loop-forming sequences can substantially limit synapsis, depending on the available dNTPs and sequence context.

[Analysis of clinical characteristics and molecular genetics in eighteen patients with 1q21.1 microdeletion syndrome].

OBJECTIVE: To explore the clinical characteristics of 1q21.1 microdeletion by using single nucleotide polymorphism microarrays (SNP array). METHODS: Eighteen cases of 1q21.1 microdeletion syndrome diagnosed at the Longgang District Maternal and Child Health Care Hospital of Shenzhen City from June 2017 to December 2022 were selected as the study subjects. Clinical data of the patients were collected. Results of chromosomal karyotyping and SNP assay were retrospectively analyzed. RESULTS: Among the 18 cases with 1q21.1 microdeletions, 13 had a deletion between BP3 and BP4, 4 had a deletion between BP1/BP2 and BP4, whilst 1 had a proximal 1q21.1 deletion (between BP2 and BP3) involving the Thrombocytopenia-absent radius (TAR) region. The deletions had spanned from 360 kb to 3.9 Mb, which encompassed the GJA5, GJA8, CHD1L, RBM8AB and other morbid genes. In three families, the proband child has inherited the same 1q21.1 microdeletion from their parents, whose clinical phenotype was normal or slightly abnormal. The clinical phenotypes of 1q21.1 microdeletion had included cognitive or behavioral deficits in 9 cases (9/18, 50.0%), growth retardation in 8 cases (8/18, 44.4%), craniofacial deformities in 7 cases (7/18, 38.8%), cardiovascular malformations in 5 cases (5/18, 27.8%), and microcephaly in 3 cases (3/18, 16.7%). CONCLUSION: 1q21.1 microdeletion syndrome has incomplete penetrance and varied expression such as intellectual impairment, growth and development delay, and microcephaly, with a wide range of non-specific phenotypes.

[Detection and Significance of Molecular Markers in Immunotherapy and Targeted Therapy of Colorectal Cancer in Tibet].

Objective To study the expression of SWI/SNF-related,matrix-associated,actin-dependent regulator of chromatin,subfamily A,member 4(SMARCA4)/Brahma-related gene 1,V-raf murine sarcoma viral oncogene homolog B(BRAF),P53,programmed cell death protein-1(PD-1),and programmed death-ligand 1(PD-L1),and changes in the expression of BRAF and neurotrophic tyrosine receptor kinase(NTRK) in the patients with colorectal cancer in Tibet,thereby providing a basis for targeted therapy and immunotherapy for this disease in Tibet. Methods A total of 64 patients with colorectal cancer resected in the Tibet Autonomous Region People's Hospital from January 2015 to July 2021 were enrolled in this study.The expression of SMARCA4,BRAF,P53,PD-1,and PD-L1 was detected by immunohistochemical staining.The gene fusion involving NTRK1,NTRK2,and NTRK3 was detected by fluorescence in situ hybridization,and the BRAF V600E gene mutation by polymerase chain reaction. Results The 64 patients with colorectal cancer were at a male-to-female ratio of 1.21∶1,with the mean age of (56.59±13.27) years.The tumors were located in the colon in 46(71.88%) patients and in the rectum in 18(28.12%) patients.Sixty(93.75%) patients presented adenocarcinoma,and 4(6.25%) patients presented other types of tumors.The patients in T1/T2 and T3/T4 phases accounted for 17.19%(n=11) and 82.81%(n=53),respectively.Lymph node metastasis occurred in 24(37.50%) patients.The immunohistochemical staining results showed partially down-regulated or absent expression of SMARCA4 in 1(1.56%) patient,positive BRAF expression in 4(6.25%) patients,and mutant expression of P53 in 35(54.69%) patients.The PD-1-expressing tumor associated immune cell was proportion score<10% in 45(70.31%) patients and≥10% in 19(29.69%) patients.The PD-L1 combined positive score was<10 in 52(81.25%) patients and≥10 in 12(18.75%) patients.The gene fusion of NTRK1,NTRK2,and NTRK3 was negative in all the patients,and BRAF V600E gene mutation was positive in 4(6.25%) patients.The SMARCA4 gene alteration was not detected in the patient with partial expression missing of SMARCA4.The PD-L1 combine positive score was correlated with the deficient mismatch repair(dMMR)/microsatellite instability-high (MSI-H) and the PD-1 expression (χ2=10.223,P=0.001;χ2=11.979,P=0.001). Conclusions The down-regulated or absent SMARCA4 expression and NTRK gene fusion are rare in the patients with colorectal cancer in Tibet.A few patients present BRAF V600E gene mutations,and Pan-TRK and BRAF expression can be used for the primary screening of NTRK gene fusion and BRAF gene mutation.The patients with dMMR/MSI-H are prone to high expression of PD-L1 and expected to benefit from immunotherapy.No significant correlation exists between P53 mutation and PD-L1 expression.The high expression of PD-1 is positively correlated with the high expression of PD-L1.

SMARCA4 (BRG1) activates ABCC3 transcription to promote hepatocellular carcinogenesis.

AIMS: Hepatocellular carcinoma (HCC) is a lead cause of cancer-related deaths. In the present study we investigated the role of Brahma-related gene 1 (BRG1), a chromatin remodeling protein, in HCC the pathogenesis focusing on identifying novel transcription targets. METHODS AND MATERIALS: Hepatocellular carcinogenesis was modeled in mice by diethylnitrosamine (DEN). Cellular transcriptome was evaluated by RNA-seq. RESULTS: Hepatocellular carcinoma was appreciably retarded in BRG1 knockout mice compared to wild type littermates. Transcriptomic analysis identified ATP Binding Cassette Subfamily C Member 3 (ABCC3) as a novel target of BRG1. BRG1 over-expression in BRG1low HCC cells (HEP1) up-regulated whereas BRG1 depletion in BRG1high HCC cells (SNU387) down-regulated ABCC3 expression. Importantly, BRG1 was detected to directly bind to the ABCC3 promoter to activate ABCC3 transcription. BRG1 over-expression in HEP1 cells promoted proliferation and migration, both of which were abrogated by ABCC3 silencing. On the contrary, BRG1 depletion in SNU387 cells decelerated proliferation and migration, both of which were rescued by ABCC3 over-expression. Importantly, high BRG1/ABCC3 expression predicted poor prognosis in HCC patients. Mechanistically, ABCC3 regulated hepatocellular carcinogenesis possibly by influencing lysosomal homeostasis. SIGNIFICANCE: In conclusion, our data suggest that targeting BRG1 and its downstream target ABCC3 can be considered as a reasonable approach for the intervention of hepatocellular carcinoma.

ARID1 and BRG1 Expression in Endometrial Cancer.

BACKGROUND/AIM: Endometrial cancer (EC) is the predominant malignancy among gynecologic cancers and ranks fourth among all types of cancer. Recently, researchers have focused on the development of new prognostic biomarkers. Subunits of the SWI/SNF protein complex, like the ARID1 and BRG1, have been associated with the development of endometrial cancer. The present study aimed to evaluate the expression patterns of ARID1A and BRG1 in a collection of endometrioid adenocarcinomas of the uterus using immunohistochemistry. PATIENTS AND METHODS: The study comprised a total of thirty-three individuals diagnosed with stage I endometrioid endometrial cancer, treated with radical hysterectomy. The histological material was then examined to assess the cytoplasmic and nuclear expression of the proteins. RESULTS: ARID1A exhibited expression in both the cytoplasm and nucleus of cancer cells, whereas BRG1 was mainly expressed in the nuclei. In addition, ARID1A exhibited a notable decrease in expression in grade 3 histology, with no significant correlation with the depth of myometrial invasion. The reduced expression was highly related to tumor expansion into the endocervix. The findings demonstrated a total absence of ARID1A expression in 27% of endometrioid carcinomas, with a significant reduction in expression in an additional 51% of cancer cells. These findings align with the most recent published data. In contrast, in the current study, BRG1 was rarely down-regulated and was extensively expressed in the majority of endometrioid carcinomas, preventing the possibility of statistical analysis. CONCLUSION: In summary, ARID1A expression loss can be used as a biomarker to guide post-operative therapy; however, further investigation is needed, especially for early-stage endometrial cancer.