FAT Atypical Cadherin 1 Research Articles

Precision therapy targeting CAMK2 to overcome resistance to EGFR inhibitors in FAT1-mutated oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) is a prevalent type of cancer with a high mortality rate in its late stages. One of the major challenges in OSCC treatment is the resistance to epidermal growth factor receptor (EGFR) inhibitors. Therefore, it is imperative to elucidate the mechanism underlying drug resistance and develop appropriate precision therapy strategies to enhance clinical efficacy. To evaluate the efficacy of the combination of the Ca2+/calmodulin-dependent protein kinase II (CAMK2) inhibitor KN93 and EGFR inhibitors, we performed in vitro and in vivo experiments using two FAT atypical cadherin 1 (FAT1)-deficient (SCC9 and SCC25) and two FAT1 wild-type (SCC47 and HN12) OSCC cell lines. We assessed the effects of EGFR inhibitors (afatinib or cetuximab), KN93, or their combination on the malignant phenotype of OSCC in vivo and in vitro. The alterations in protein expression levels of members of the EGFR signaling pathway and SRY-box transcription factor 2 (SOX2) were analyzed. Changes in the yes-associated protein 1 (YAP1) protein were characterized. Moreover, we analyzed mitochondrial dysfunction. Besides, the effects of combination therapy on mitochondrial dynamics were also evaluated. OSCC with FAT1 mutations exhibited resistance to EGFR inhibitors treatment. The combination of KN93 and EGFR inhibitors significantly inhibited the proliferation, survival, and migration of FAT1-mutated OSCC cells and suppressed tumor growth in vivo. Mechanistically, combination therapy enhanced the therapeutic sensitivity of FAT1-mutated OSCC cells to EGFR inhibitors by modulating the EGFR pathway and downregulated tumor stemness-related proteins. Furthermore, combination therapy induced reactive oxygen species (ROS)-mediated mitochondrial dysfunction and disrupted mitochondrial dynamics, ultimately resulting in tumor suppression. Combination therapy with EGFR inhibitors and KN93 could be a novel precision therapeutic strategy and a potential clinical solution for EGFR-resistant OSCC patients with FAT1 mutations.

Gene mutation characteristics of clinical stage ⅠA lung adenocarcinoma and their relations with patients' long-term prognosis

Objective: To explore the gene mutation characteristics and the relationship between gene mutations and long-term prognosis in clinical stage ⅠA lung adenocarcinoma patients. Methods: A retrospective analysis was conducted on 63 clinical stage ⅠA lung adenocarcinoma patients who underwent surgical resection at the Cancer Hospital of the Chinese Academy of Medical Sciences from January 2007 to October 2012, with documented postoperative recurrence or metastasis, as well as those who had a follow-up duration of 10 years or more without recurrence or metastasis. Whole exome sequencing (WES) technology was used to analyze the gene mutation profiles in tumor tissues and univariate and multivariate Cox regression analysis were used to clarify the influencing factors for patient prognosis. Results: After long term follow-up, 13 out of the 63 patients (21%) experienced recurrence or metastasis. WES technology analysis revealed that the most common tumor related gene mutations occurred in epidermal growth factor receptor (EGFR), with a mutation rate of 65.1% (41/63), followed by tumor protein p53 (TP53), fatatypical cadherin 1 (FAT1), low density lipoprotein receptor-related protein 1B (LRP1B), mechanistic target of rapamycin (MTOR), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit gamma (PIK3CG), and SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily A, member 4 (SMARCA4), with mutation rates of 30.2% (19/63), 20.6% (13/63), 15.9% (10/63), 15.9% (10/63), 15.9% (10/63), and 15.9% (10/63), respectively. Multivariate Cox regression analysis showed that PIK3CG mutations (HR=21.52, 95% CI: 3.19-145.01),smoothened (SMO) mutations (HR=35.28, 95% CI: 3.12-398.39), catenin beta 1 (CTNNB1) mutations (HR=332.86, 95% CI: 15.76-7 029.05), colony stimulating factor 1 receptor (CSF1R) mutations (HR=8 109.60, 95% CI: 114.19-575 955.17), and v-Raf murine sarcoma viral oncogene homolog B (BRAF) mutations (HR=23.65, 95% CI: 1.86-300.43) were independent risk factors affecting the prognosis of clinical stage ⅠA lung adenocarcinoma patients. Conclusions: PIK3CG, SMO, CTNNB1, CSF1R, BRAF gene mutations are closely related to long-term recurrence or metastasis in clinical stage ⅠA lung adenocarcinoma. Patients with these gene mutations should be given closer clinical attention.

FAT1 inhibits the proliferation of DLBCL cells via increasing the m6A modification of YAP1 mRNA

Emerging evidence shows that FAT atypical cadherin 1 (FAT1) mutations occur in lymphoma and are associated with poorer overall survival. Considering that diffuse large B cell lymphoma (DLBCL) is the category of lymphoma with the highest incidence rate, this study aims to explore the role of FAT1 in DLBCL. The findings demonstrate that FAT1 inhibits the proliferation of DLBCL cell lines by downregulating the expression of YAP1 rather than by altering its cellular localization. Mechanistic analysis via meRIP-qPCR/luciferase reporter assays showed that FAT1 increases the m6A modification of YAP1 mRNA 3′UTR and the subsequent binding of heterogeneous nuclear ribonucleoprotein D (HNRNPD) to the m6A modified YAP1 mRNA, thus decreasing the stability of YAP1 mRNA. Furthermore, FAT1 increases YAP1 mRNA 3′UTR m6A modification by decreasing the activity of the TGFβ-Smad2/3 pathway and the subsequent expression of ALKBH5, which is regulated at the transcriptional level by Smad2/3. Collectively, these results reveal that FAT1 inhibits the proliferation of DLBCL cells by increasing the m6A modification of the YAP1 mRNA 3’UTR via the TGFβ-Smad2/3-ALKBH5 pathway. The findings of this study therefore indicate that FAT1 exerts anti-tumor effects in DLBCL and may represent a novel target in the treatment of this form of lymphoma.

Expression of FAT1 in Lung Adenocarcinoma and Its Relationship with Immune Cell Infiltration

Lung cancer is a leading cause of cancer-related deaths. Non-small cell lung cancer (NSCLC) is the most common pathological subtype, with adenocarcinoma being the predominant type. FAT atypical cadherin 1 (FAT1) is a receptor-like protein with a high frequency of mutations in lung adenocarcinoma. The protein encoded by FAT1 plays a crucial role in processes such as cell adhesion, proliferation, and differentiation. This study aims to investigate the expression of FAT1 in lung adenocarcinoma and its relationship with immune infiltration. Gene expression levels and relevant clinical information of 513 lung adenocarcinoma samples and 397 adjacent lung samples were obtained through The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) data. The mRNA expression levels of the FAT1 gene in lung adenocarcinoma tissues were analyzed, along with its association with the prognosis of lung adenocarcinoma patients. Pathway enrichment analysis was conducted to explore the signaling pathways regulated by the FAT1 gene. Immunoblotting was used to detect the differential expression of FAT1 in lung epithelial cells and various lung cancer cell lines, while immunohistochemistry was employed to assess FAT1 expression in lung cancer and adjacent tissues. FAT1 gene mutations were identified in 14% of lung adenocarcinoma patients. TCGA database data revealed significantly higher FAT1 mRNA expression in lung adenocarcinoma tissues compared to adjacent lung tissues. Kaplan-Meier analysis indicated lower survival rates in lung adenocarcinoma patients with higher FAT gene expression. Pathway enrichment analysis suggested the involvement of FAT1 in tumor development pathways, and its expression was closely associated with immune cell infiltration. Immunohistochemical validation demonstrated significantly higher expression of FAT1 in cancer tissues compared to adjacent lung tissues. FAT1 mRNA is highly expressed in lung adenocarcinoma tissues, and elevated FAT1 mRNA expression is associated with poor prognosis in lung adenocarcinoma patients. FAT1 may serve as a potential biomarker for lung cancer.

Co-Expression Network Analysis and Molecular Docking Demonstrate That Diosgenin Inhibits Gastric Cancer Progression via SLC1A5/mTORC1 Pathway.

Tumor-Node-Metastasis (TNM) stage of gastric cancer (GC) is one of the main factors affecting clinical outcome. The aim of this study was to explore the targets related to TNM stage of GC, and screening natural bioactive drug. RNA sequencing data of the TCGA-STAD cohort were downloaded from UCSC database. Genes associated with TNM staging were identified by weighted gene co-expression network analysis (WGCNA). Univariate Cox regression, least absolute shrinkage and selection operator (LASSO), extreme gradient boosting (Xgboost), random forest (RF) and cytohubba plug-in of cytoscope were applied to screen hub genes. Natural bioactive ingredients were available from the HERB database. Molecular docking was used to evaluate the binding activity of active ingredients to the hub protein. CCK-8, flow cytometry, transwell and Western blot assays were used to analyze the effects of diosgenin on GC cells. 898 TNM-related genes were screened out through WGCNA. Three genes associated with GC progression/prognosis were identified, including nuclear receptor subfamily 3 group C member 2 (NR3C2), solute carrier family 1 member 5 (SLC1A5) and FAT atypical cadherin 1 (FAT1) based on the machine learning algorithms and hub co-expression network analysis. Diosgenin had good binding activity with SLC1A5. SLC1A5 was highly expressed in GC and was closely associated with tumor stage, overall survival and immune infiltration of GC patients. Diosgenin could inhibit cell viability and invasive ability, promote apoptosis and induce cell cycle arrest in G0/G1 phase. In addition, diosgenin promoted cleaved caspase 3 expression and inhibited Ki67, cyclin D1, p-S6K1, and SLC1A5 expression levels, while the mTORC1 activator (MHY1485) reversed this phenomenon. For the first time, this work reports diosgenin may inhibit the activation of mTORC1 signaling through targeting SLC1A5, thereby inhibiting the malignant behaviors of GC cells.

FAT1 inhibits AML autophagy and proliferation via downregulating ATG4B expression

BackgroundEmerging studies have shown that FAT atypical cadherin 1 (FAT1) and autophagy separately inhibits and promotes acute myeloid leukemia (AML) proliferation. However, it is unknown whether FAT1 were associated with autophagy in regulating AML proliferation. MethodsAML cell lines, 6-week-old male nude mice and AML patient samples were used in this study. qPCR/Western blot and cell viability/3H-TdR incorporation assays were separately used to detect mRNA/protein levels and cell activity/proliferation. Luciferase reporter assay was used to examine gene promoter activity. Co-IP analysis was used to detect the binding of proteins. ResultsIn this study, we for the first time demonstrated that FAT1 inhibited AML proliferation by decreasing AML autophagy level. Moreover, FAT1 weakened AML autophagy level via decreasing autophagy related 4B (ATG4B) expression. Mechanistically, we found that FAT1 reduced the phosphorylated and intranuclear SMAD family member 2/3 (smad2/3) protein levels, thus decreasing the activity of ATG4B gene promoter. Furthermore, we found that FAT1 competitively bound to TGF-βR II which decreased the binding of TGF-βR II to TGF-βR I and the subsequent phosphorylation of TGF-βR I, thus reducing the phosphorylation and intranuclear smad2/3. The experiments in nude mice showed that knockdown of FAT1 promoted AML autophagy and proliferation in vivo. ConclusionsCollectively, these results revealed that FAT1 downregulates ATG4B expression via inhibiting TGFβ-smad2/3 signaling activity, thus decreasing the autophagy level and proliferation activity of AML cells. General significanceOur study suggested that the “FAT1-TGFβ-smad2/3-ATG4B-autophagy” pathway may be a novel target for developing new targeted drugs to AML treatment.

Investigating the cell membrane localization of PADI4 in breast cancer cells and inhibition of anti-PADI4 monoclonal antibody

BackgroundPeptidyl arginine deiminase 4 (PADI4) is a post-translational modification enzymecan that converts arginine in protein into citrulline in the presence of calcium ions, which is called citrullination. PADI4 has been reported to be expressed in the cytoplasm and nucleus in a variety of malignant tumors. Based on the GeneCards database and our previous research, it is speculated that PADI4 may also be expressed on the cell membrane. This study aimed to confirm the membrane expression of PADI4 and the effect of anti-PADI4 antibodies on cell membrane PADI4. This may be another mechanism of action of anti-PADI4 monoclonal antibodies in the treatment of breast cancer.MethodsThe subcellular localizations of PADI4 in MDA-MB-231 and MCF-7 breast cancer cells were determined by immunofluorescence, immunoelectron microscopy, and Western blot analysis. The tumor cells were treated with PADI4 antibody, and cell proliferation, migration, colony formation, apoptosis, glycolysis, and epithelial-mesenchymal transition (EMT) were measured as well as the expression of some essential tumor genes.ResultsPADI4 was not only localized in the nucleus and cytoplasm of breast cancer cells but was also detected on the cell membrane. Following PADI4 antibody treatment, cell proliferation, migration, colony formation, EMT, and ATP production through glycolysis were decreased, and the mRNA expression of MYC proto-oncogene (MYC), FAT atypical cadherin 1 (FAT1), nuclear factor kappa B subunit 1 (NFκB), and tumor necrosis factor (TNF-α) in breast cancer cells was downregulated, while the mRNA expression of tumor protein p63 (TP63) was upregulated.ConclusionsPADI4 is expressed on the cell membrane in breast cancer cells. Anti-PADI4 antibodies can affect the biological functions of cell membrane PADI4, including proliferation, migration, apoptosis, and glycolysis, thereby inhibiting tumor progression.Graphical abstract

The Distinctive Features behind the Aggressiveness of Oral and Cutaneous Squamous Cell Carcinomas

Squamous cell carcinomas arise from stratified squamous epithelia. Here, a comparative analysis based on recent studies defining the genetic alterations and composition of the stroma of oral and cutaneous squamous cell carcinomas (OSCC and CSCC, respectively) was performed. Both carcinomas share some but not all histological and genetic features. This review was focused on how mutations in tumor suppressor genes and protooncogenes cooperate to determine the differentiation, aggressiveness, and metastatic potential of OSCC and CSCC. In fact, driver mutations in tumor suppressor genes are more frequently observed in OSCC than CSCC. These include mutations in TP53 (encoding pP53 protein), CDKN2A (encoding cyclin dependent kinase inhibitor 2A), FAT1 (encoding FAT atypical cadherin 1), and KMT2D (encoding lysine methyltransferase 2D), with the exception of NOTCH (encoding Notch receptor 1), whose mutation frequency is lower in OSCC compared to CSCC. Finally, we describe the differential composition of the tumor microenvironment and how this influences the aggressiveness of each tumor type. Although both OSCC and CSCC tumors are highly infiltrated by immune cells, high levels of tumor-infiltrating lymphocytes (TILs) have been more frequently reported as predictors of better outcomes in OSCC than CSCC. In conclusion, OSCC and CSCC partially share genetic alterations and possess different causal factors triggering their development. The tumor microenvironment plays a key role determining the outcome of the disease.

FAT1 Gene Expression in Iranian Acute Lymphoid and Myeloid Leukemia Patients.

FAT atypical cadherin 1 (FAT1) is a member of the cadherin superfamily whose loss or gain is associated with the initiation and/or progression of different cancers. FAT1 overexpression has been reported in hematological malignancies. This research intended to investigate FAT1 gene expression in adult Iranian acute leukemia patients, compared to normal mobilized peripheral blood CD34+ cells. The peripheral blast (peripheral blood mononuclear cells) cells of 22 acute myeloid leukemia (AML), 14 acute lymphoid leukemia (ALL) patients, and mobilized peripheral blood CD34+ cells of 12 healthy volunteer stem cell donors were collected. Then, quantitative real-time polymerase chain reaction (qPCR) was used to compare FAT1 gene expression. Overall, there were no significant differences in FAT1 expression between AML and ALL patients (p>0.2). Nonetheless, the mean expression level of FAT1 was significantly higher in leukemic patients (AML and ALL) than in normal CD34+ cells (p=0.029). Additionally, the FAT1 expression levels were significantly higher in both CD34+ and CD34- leukemic patients than in normal CD34+ cells (p=0.028). No significant differences were found between FAT1 expression in CD34+ and CD34- leukemic samples (p> 0.3). Thus, higher FAT1 expression was evident in ALL and AML leukemia cells but this appeared unrelated to CD34 expression. This suggests in a proportion of adult acute leukemia, FAT1 expression may prove to be a suitable target for therapeutic strategies.

Comprehensive Genomic Profiling Identifies FAT1 as a Negative Regulator of EMT, CTCs, and Metastasis of Hepatocellular Carcinoma.

FAT atypical cadherin 1 (FAT1) acts as a tumor suppressor or oncogene, which regulates cell adherence, proliferation, motility, and actin kinetics. FAT1 gene expression is closely related to hepatocarcinogenesis; however, the function and mechanism of FAT1 in hepatocellular carcinoma (HCC) remain unclear. Here, we screened for the FAT1, which is intimately linked to the development and progression of HCC, both in circulating tumor cells (CTCs) and tumor tissues using next generation sequencing (NGS). Immunohistochemical staining was performed to detect FAT1 protein expression. To determine the impact of FAT1 on epithelial-mesenchymal transition (EMT), migration and invasion of HCC, an in vitrotranswell assay and Western blot were performed. Moreover, Gene Set Enrichment Analysis was carried out to discover the underlying mechanism. Finally, animal experimentswere conducted to confirm the effects of FAT1 on HCC metastasis and tumorigenicity. Our results showed that FAT1 expression was decreased in HCC tissues, while in vitro and in vivo, the FAT1 knockdown facilitated invasion, cell motility, colony formation, and proliferation. FAT1 knockdown also resulted in decreased expression of E-cadherin and markedly elevated expression of N-cadherin, vimentin, and snail. We also confirmed our hypothesis from the analysis of group differences in the CTC phenotype and lung metastasis in nude mice. Our findings illustrated that FAT1 played a negative regulatory role in the HCC EMT and metastasis, providing further evidence for the role played by FAT1 in the formation and progression of HCC.

FAT1 expression in T-cell acute lymphoblastic leukemia (T-ALL) modulates proliferation and WNT signaling

FAT atypical cadherin 1 (FAT1), a transmembrane protein, is frequently mutated in various cancer types and has been described as context-dependent tumor suppressor or oncogene. The FAT1 gene is mutated in 12–16% of T-cell acute leukemia (T-ALL) and aberrantly expressed in about 54% of T-ALL cases contrasted with absent expression in normal T-cells. Here, we characterized FAT1 expression and profiled the methylation status from T-ALL patients. In our T-ALL cohort, 53% of patient samples were FAT1 positive (FAT1pos) compared to only 16% FAT1 positivity in early T-ALL patient samples. Aberrant expression of FAT1 was strongly associated with FAT1 promotor hypomethylation, yet a subset, mainly consisting of TLX1-driven T-ALL patient samples showed methylation-independent high FAT1 expression. Genes correlating with FAT1 expression revealed enrichment in WNT signaling genes representing the most enriched single pathway. FAT1 knockdown or knockout led to impaired proliferation and downregulation of WNT pathway target genes (CCND1, MYC, LEF1), while FAT1 overexpressing conveyed a proliferative advantage. To conclude, we characterized a subtype pattern of FAT1 gene expression in adult T-ALL patients correlating with promotor methylation status. FAT1 dependent proliferation and WNT signaling discloses an impact on deeper understanding of T-ALL leukemogenesis as a fundament for prospective therapeutic strategies.

A pan-cancer analysis of the FAT1 in human tumors

FAT atypical cadherin 1 (FAT1) is one of the most mutagenic genes in tumors, and several critical studies have revealed its role in tumors, although no pan-cancer studies are currently available. Therefore, we explored the potential oncogenic role of FAT1 in 33 tumors based on The Cancer Genome Atlas and Gene Expression Omibus datasets. We found that FAT1 was strongly expressed in most tumors and significantly correlated with their prognosis. Additionally, we analyzed the association of FAT1 with tumors from multiple perspectives, including single-cell sequencing, mutations, high tumor mutational burden, microsatellite instability, immune cell infiltration, and immune microenvironment. Our first pan-cancer study provided a relatively comprehensive understanding of the oncogenic role of FAT1 in tumors.

Oncogenic LINC00857 recruits TFAP2C to elevate FAT1 expression in gastric cancer.

FAT atypical cadherin 1 (FAT1) is a mutant gene frequently found in human cancers and mainly accumulates at the plasma membrane of cancer cells. Emerging evidence has implicated FAT1 in the progression of gastric cancer (GC). This study intended to identify a regulatory network related to FAT1 in GC development. Upregulated expression of FAT1 was confirmed in GC tissues, and silencing FAT1 was observed to result in suppression of GC cell oncogenic phenotypes. Mechanistic investigation results demonstrated that FAT1 upregulated AP-1 expression by phosphorylating c-JUN and c-FOS, whereas LINC00857 elevated the expression of FAT1 by recruiting a transcription factor TFAP2C. Functional experiments further suggested that LINC00857 enhanced the malignant biological characteristics of GC cells through TFAP2C-mediated promotion of FAT1. More importantly, LINC00857 silencing delayed the tumor growth and blocked epithelial-mesenchymal transition in tumor-bearing mice, which was associated with downregulated expression of TFAP2C/FAT1. To conclude, LINC00857 plays an oncogenic role in GC through regulating the TFAP2C/FAT1/AP-1 axis. Therefore, this study contributes to extended the understanding of gastric carcinogenesis and LINC00857 may serve as a therapeutic target for GC.

Favorable immune checkpoint inhibitor outcome of patients with melanoma and NSCLC harboring FAT1 mutations

Immune checkpoint inhibitors (ICIs) are most commonly used for melanoma and non-small cell lung cancer (NSCLC) patients. FAT atypical cadherin 1 (FAT1), which frequently mutates in melanoma and NSCLC. In this study, we aim to investigate the association of FAT1 mutations with ICI response and outcome. We collected somatic mutation profiles and clinical information from ICI-treated 631 melanoma and 109 NSCLC samples, respectively. For validation, a pan-cancer cohort with 1661 patients in an immunotherapy setting was also used. Melanoma and NSCLC samples from the Cancer Genome Atlas were used to evaluate the potential immunologic mechanisms of FAT1 mutations. In melanoma, patients with FAT1 mutations had a significantly improved survival outcome than those wild-type patients (HR: 0.67, 95% CI: 0.46–0.97, P = 0.033). An elevated ICI response rate also appeared in FAT1-mutated patients (43.2% vs. 29.2%, P = 0.032). Associations of FAT1 mutations with improved prognosis and ICI response were confirmed in NSCLC patients. In the pan-cancer cohort, the association between FAT1 mutations and favorable ICI outcome was further validated (HR: 0.74, 95% CI: 0.58–0.96, P = 0.022). Genomic and immunologic analysis showed that a high mutational burden, increased infiltration of immune-response cells, decreased infiltration of immune-suppressive cells, interferon and cell cycle-related pathways were enriched in patients with FAT1 mutations. Our study revealed that FAT1 mutations were associated with better immunogenicity and ICI efficacy, which may be considered as a biomarker for selecting patients to receive immunotherapy.

Upregulation of Atypical Cadherin FAT1 Promotes an Immunosuppressive Tumor Microenvironment via TGF-β.

FAT atypical cadherin 1 (FAT1) promotes glioblastoma (GBM) by promoting protumorigenic inflammatory cytokine expression in tumor cells. However, tumors also have an immunosuppressive microenvironment maintained by mediators such as transforming growth factor (TGF)-β cytokines. Here, we have studied the role of FAT1 in tumor immune suppression. Our preliminary TIMER2.0 analysis of The Cancer Genome Atlas (TCGA) database revealed an inverse correlation of FAT1 expression with infiltration of tumor-inhibiting immune cells (such as monocytes and T cells) and a positive correlation with tumor-promoting immune cells [such as myeloid-derived suppressor cells (MDSCs)] in various cancers. We have analyzed the role of FAT1 in modulating the expression of TGF-β1/2 in resected human gliomas, primary glioma cultures, and other cancer cell lines (U87MG, HepG2, Panc-1, and HeLa). Positive correlations of gene expression of FAT1 and TGF-β1/2 were observed in various cancers in TCGA, Glioma Longitudinal Analysis Consortium (GLASS), and Chinese Glioma Genome Atlas (CGGA) databases. Positive expression correlations of FAT1 were also found with TGF-β1/2 and Serpine1 (downstream target) in fresh-frozen GBM samples using q-PCR. siRNA-mediated FAT1 knockdown in cancer cell lines and in primary cultures led to decreased TGF-β1/2 expression/secretion as assessed by q-PCR, Western blotting, and ELISA. There was increased chemotaxis (transmigration) of THP-1 monocytes toward siFAT1-transfected tumor cell supernatant as a consequence of decreased TGF-β1/2 secretion. Reduced TGF-β1 expression was also observed in THP-1 cultured in conditioned media from FAT1-depleted glioma cells, thus contributing to immune suppression. In U87MG cells, decreased TGF-β1 upon FAT1 knockdown was mediated by miR-663a, a known modulator. FAT1 expression was also observed to correlate positively with the expression of surrogate markers of MDSCs [programmed death ligand-1 (PD-L1), PD-L2, and interleukin (IL)-10] in glioma tumors, suggesting a potential role of FAT1 in MDSC-mediated immunosuppression. Hence, our findings elaborate contributions of FAT1 to immune evasion, where FAT1 enables an immunosuppressive microenvironment in GBM and other cancers via TGF-β1/2.

FAT1 downregulation enhances stemness and cisplatin resistance in esophageal squamous cell carcinoma.

Primary or acquired drug resistance accounts for the failure of chemotherapy and cancer recurrence in esophageal squamous cell carcinoma (ESCC). However, the aberrant mechanisms driving drug resistance are not fully understood in ESCC. In our previous study, FAT Atypical Cadherin 1 (FAT1) was found to inhibit the epithelial-mesenchymal transition (EMT) process in ESCC. EMT plays a critical role in the development of drug resistance in multiple cancer types. Besides, it equips cancer cells with cancer stem cell (CSC)-like characters that also are associated with chemotherapy resistance. Whether FAT1 regulates the stemness or drug resistance of ESCC cells is worth being explored. Here we found that FAT1 was downregulated in ESCC spheres and negatively correlated with stemness-associated markers including ALDH1A1 and KLF4. Knocking down FAT1 enhanced the sphere-forming ability, resistance to cisplatin and drug efflux of ESCC cells. Additionally, FAT1 knockdown upregulated the expression of drug resistance-related gene ABCC3. Furtherly, we found FAT1 knockdown induced the translocation of β-catenin into nucleus and enhanced its transcriptional activity. The result of ChIP showed that β-catenin was enriched in ABCC3 promoter. Furthermore, β-catenin promoted expression of ABCC3. In conclusion, FAT1 knockdown might enhance the stemness and ABCC3-related cisplatin resistance of ESCC cells via Wnt/β-catenin signaling pathway. FAT1 and its downstream gene ABCC3 might be potential targets for overcoming chemoresistance in ESCC.

FAT1 Upregulates in Oral Squamous Cell Carcinoma and Promotes Cell Proliferation via Cell Cycle and DNA Repair.

ObjectivePrevious studies have revealed that FAT atypical cadherin 1 (FAT1) plays a tumor-suppressive or oncogenic role in a context-dependent manner in various cancers. However, the functions of FAT1 are ambiguous in tumorigenesis owing to inconsistent research in oral squamous cell carcinoma (OSCC). The present study aimed at gaining an insight into the role of FAT1 in the tumor genesis and development.MethodsThe expression, mutant, and survival data analyses were done using data from The Cancer Genome Atlas (TCGA), the Gene Expression Omnibus (GEO), and the Clinical Proteomic Tumor Analysis Consortium (CPTAC) database, verified with clinical samples via real-time polymerase chain reaction (qRT-PCR), Western blot (WB), and immunohistochemical (IHC) staining. OSCC cells transfected with siRNA were employed for in vitro assessment in cell proliferation, apoptosis, and migration ability in appropriate ways. The underlying mechanism was explored by RNA sequencing after FAT1 silencing.ResultsOverall, FAT1 significantly increased in OSCC with a poor prognosis outcome. The in vitro experiment showed the promoting effect of FAT1 in the proliferation and migration of OSCC cells. FAT1 can also inhibit both the early and late apoptosis of OSCC cells. RNA-sequencing analysis of FAT1 silencing revealed that the cell cycle, DNA replication, and some core genes (MCM2, MCM5, CCNE1 SPC24, MYBL2, KIF2C) may be the potential mechanism in OSCC.ConclusionsFAT1 may act as an oncogene in OSCC with potential mechanism influencing the cell cycle and DNA repair.

MiR-29b-1-5p regulates the proliferation and differentiation of chicken primary myoblasts and analysis of its effective targets

Several recent studies investigated the role of the miR-29 family in muscle development. However, only a few studies focused on chicken skeletal muscle. In the present study, cell cycle, 5-ethynyl-2’-deoxyuridine (EdU), cell counting kit-8 (CCK-8), and other assays indicated that miR-29b-1-5p can inhibit the proliferation of chicken primary myoblasts (CPMs); the western blot assay and immunofluorescence detection of MYHC demonstrated that miR-29b-1-5p can promote the differentiation of myoblasts. The functional enrichment analysis revealed that the target genes of miR-29b-1-5p may be involved in muscle tissue development, muscle organ development, and striated muscle tissue development, which are biological processes related to muscle development. The correlation analysis showed that these 6 genes, that is, ankyrin repeat domain 9 (ANKRD9), lactate dehydrogenase A (LDHA), transcription factor 12 (TCF12), FAT atypical cadherin 1 (FAT1), lin-9 homolog (LIN9), and integrin beta 3 binding protein (ITGB3BP), can be used as effective candidate target genes of miR-29b-1-5p. Moreover, miR-29b-1-5p inhibits the expression of ANKRD9 by directly binding the 3′UTR of ANKRD9. Overall, these data indicate that miR-29b-1-5p inhibits the proliferation of primary chicken myoblasts, stimulates their differentiation, and is involved in the process of muscle development and that its effective target gene is ANKRD9. This study identified the molecular mechanism of miR-29b-1-5p in chicken muscle development.

Postnatal expression profiles of atypical cadherin FAT1 suggest its role in autism.

ABSTRACTGenetic studies have linked FAT1 (FAT atypical cadherin 1) with autism spectrum disorder (ASD); however, the role that FAT1 plays in ASD remains unknown. In mice, the function of Fat1 has been primarily implicated in embryonic nervous system development with less known about its role in postnatal development. We show for the first time that FAT1 protein is expressed in mouse postnatal brains and is enriched in the cerebellum, where it localizes to granule neurons and Golgi cells in the granule layer, as well as inhibitory neurons in the molecular layer. Furthermore, subcellular characterization revealed FAT1 localization in neurites and soma of granule neurons, as well as being present in the synaptic plasma membrane and postsynaptic densities. Interestingly, FAT1 expression was decreased in induced pluripotent stem cell (iPSC)-derived neural precursor cells (NPCs) from individuals with ASD. These findings suggest a novel role for FAT1 in postnatal development and may be particularly important for cerebellum function. As the cerebellum is one of the vulnerable brain regions in ASD, our study warrants further investigation of FAT1 in the disease etiology.

β-Catenin and FAT1 Protein Expressions for Prediction of Survival Outcome in Type I Endometrial Cancer

ackground: Endometrial cancer (EC) is the second most common female genital tract malignancy and has adverse outcome in the advanced stage. A prognostic marker is needed for marking an accurate prognostic. Objective: To evaluate expression and clinical outcome of CTNNB1 (β-catenin) and FAT atypical cadherin 1 (FAT1), by using immunohistochemical staining in EC type I. Materials and Methods: Seventy-two EC type I cases were selected from Songklanagarind Hospital with clinical data collection. All cases were evaluated by immunohistochemistry using antibodies against β-catenin and FAT1. Results: All cases of EC type I were β-catenin positive and FAT1 negative. Moderate and strong intensity (2+ and 3+) β-catenin cytoplasmic staining showed statistically significant association with low grade EC, and low risk of recurrence disease or metastasis (p<0.05). β-catenin nuclear staining was present in 19 of 28 cases (68%) of EC grade 1 and associated with low grade EC. β-catenin and FAT1 expression were not associated with 5-year overall survival in both univariate and multivariate analyses. Conclusion: β-catenin cytoplasmic staining may be associated with low grade EC, and helpful to predict recurrent risk. However, FAT1 and β-catenin expressions have no statically significant correlation with 5-year overall survival and cannot be used to determine the prognosis in type I EC patients. Keywords: β-catenin, FAT1, Immunohistochemistry, Metastasis, Recurrence, Survival outcome, Type I endometrial cancer