SATB1 is a Novel Molecular Target for Cancer Therapy

Non-Specific Epileptic Activity, EEG, and Brain Imaging in Loss of Function Variants in SATB1: A New Case Report and Review of the Literature

SATB1 (MIM #602075) is a relatively new gene reported only in recent years in association with neurodevelopmental disorders characterized by variable facial dysmorphisms, global developmental delay, poor or absent speech, altered electroencephalogram (EEG), and brain abnormalities on imaging. To date about thirty variants in forty-four patients/children have been described, with a heterogeneous spectrum of clinical manifestations. In the present study, we describe a new patient affected by mild intellectual disability, speech disorder, and non-specific abnormalities on EEG and neuroimaging. Family studies identified a new de novo frameshift variant c.1818delG (p.(Gln606Hisfs*101)) in SATB1. To better define genotype-phenotype associations in the different types of reported SATB1 variants, we reviewed clinical data from our patient and from the literature and compared manifestations (epileptic activity, EEG abnormalities and abnormal brain imaging) due to missense variants versus those attributable to loss-of-function/premature termination variants. Our analyses showed that the latter variants are associated with less severe, non-specific clinical features when compared with the more severe phenotypes due to missense variants. These findings provide new insights into SATB1-related disorders.

Special AT-rich sequence binding protein 1 promotes multidrug resistance in gastric cancer by regulation of Ezrin to alter subcellular localization of ATP-binding cassette transporters

Multidrug resistance is a primary factor in the poor response to chemotherapy and subsequent death in gastric cancer patients. However, the molecular mechanisms involved remain unclear. In this study, the high expression of special AT-rich sequence binding protein 1 (SATB1) in gastric cancer was found to be associated with reduced sensitivity to various chemotherapy drugs. Our results demonstrate that SATB1 can promote chemotherapy resistance in gastric cancer in vitro and in vivo. SATB1 exerts its effect by enhancing the activity of multiple ATP-binding cassette (ABC) transporters (P-glycoprotein, multidrug resistance-associated protein, and breast cancer resistance protein) in gastric cancer cell lines. We also found that SATB1 affects ABC transporters by altering the subcellular localization of the ABC transporter rather than its expression. Subsequently, we confirmed that Ezrin binds to various ABC transporters and affects their subcellular localization. In addition, we found that SATB1 can also bind to the Ezrin promoter and regulate its expression. In the present study, we elucidate the mechanism of SATB1-mediated multidrug resistance in gastric cancer, providing a basis for SATB1 as a potential target for reversal of resistance.

MicroRNA-409 regulates the proliferation and invasion of breast cancer cell lines by targeting special AT-rich sequence-binding protein 1 (SATB1)

This study aims to determine the cellular functions and clinical significance of microRNA-409 (miR-409) in breast cancer by targeting special AT-rich sequence-binding protein 1 (SATB1). Breast cancer tissues and adjacent normal tissues, breast cancer cell lines (MDA-MB-453, MDA-MB-231, BT-549, BR3, and MCF-7) were used. miR-409 mimics, miR-409 inhibitor, SATB1, and siSATB1 were transiently transduced into cancer cells independently or together. RT-qPCR, Western blot, Cell Counting Kit-8 (CCK8), and Transwell assays were carried out to analyze the expression, cellular proliferation, and invasion. The results showed that the expression of miR-409 in breast cancer tissues is lower than that in adjacent tissues. The application of a target prediction algorithm predicts that the candidate gene regulated by miR-409 may be SATB1. The expression level of miR-409 in MDA-MB-453 cells is lower, while in BT-549 cells it is higher, when compared with MDA-MB-231, BR3, and MCF-7. The proliferation rate and invasive ability of MDA-MB-453 cells transfected with the miR-409 mimic was significantly lower than that of the miRNA negative control (miR-NC) cells, while the proliferation rate and invasive ability of BT-549 cells transfected with the miR-409 inhibitor were significantly increased. Cell proliferation and invasion of miR-409 mimic and SATB1 co-transfected MDA-MB-453 cells increased compared with that of miR-409 mimic-transfected cells, while miR-409 inhibitor and siSATB1 co-transfected BT-549 cells showed the opposite result. All these results indicated that miR-409 regulates breast cancer proliferation and invasion by targeting SATB1 and might be a potential therapeutic target for the treatment of breast cancer.

Elevated Expression of SATB1 Predicts Unfavorable Clinical Outcomes in Colon Adenocarcinoma

BACKGROUNDS

Special AT-rich sequence-binding protein 1 (SATB1) belongs to the chromatin-remodeling protein which regulates different genes expression. High expression of SATB1 was found to be associated with the development of certain carcinomas. However, the functions of SATB1 in colon adenocarcinoma (CAC) remains unclear yet. Our study aims to investigate the potential role of SATB1 in CAC and whether it is associated with the unfavorable symptoms of CAC patients.

METHODS

The expression pattern of SATB1 was measured in CAC samples and adjacent noncancerous samples through quantitative real-time polymerase chain reaction and immunohistochemistry staining. We performed univariate and multivariate analyses to evaluate the clinical role of SATB1 in enrolled patients. The Kaplan-Meier analyses and log-rank tests were carried out to assess the clinicopathologic characteristics. The effect of SATB1 in human colon cancer cells was examined through cellular experiments.

RESULTS

The expression level of SATB1 in CAC tissues was significantly elevated compared with adjacent control tissues. High expression of SATB1 in tumor tissue was found to be associated with lymph node metastasis and advanced TNM stage. Higher SATB1 level in CAC patients indicated a worse 5-year survival time. Moreover, high SATB1 was defined as an independent poor prognostic factor. Cellular experiments showed that inhibition of the SATB1 protein level in human colon cells could suppress the migration and invasion capabilities.

CONCLUSIONS

Our findings revealed that high expression of SATB1 was significantly correlated with the poor clinical features and prognosis of CAC patients. It indicated that SATB1 might serve as a potential prognostic predictor and novel drug target for CAC treatment.

MicroRNA-448 targets SATB1 to reverse the cisplatin resistance in lung cancer via mediating Wnt/β-catenin signalling pathway

This study aims to examine whether miR-448 reverses the cisplatin (DDP) resistance in lung cancer by modulating SATB1. QRT-PCR and immunohistochemistry were used to examine the miR-448 and SATB1 expressions in DDP-sensitive and -resistant lung cancer patients. A microarray was used to investigate the cytoplasmic/nucleic ratio (C/N ratios) of genes in A549 cells targeted by miR-448, followed by Dual-luciferase reporter gene assay. A549/DDP cells were transfected with miR-448 mimics/inhibitors with or without SATB1 siRNA followed by MTT assay, Edu staining, flow cytometry, qRT-PCR and western blotting. MiR-448 was lower but SATB1 was increased in DDP-resistant patients and A549/DDP cells. And the patients showed low miR-448 expression or SATB1 positive expression had poor prognosis. SATB1, as a target gene with higher C/N ratios (>1), was found negatively regulated by miR-448. Besides, miR-448 inhibitors increased resistance index of A549/DDP cells, promoted cell proliferation, increased cell distribution in S phrase, declined cell apoptosis and activated Wnt/β-catenin pathway. However, SATB1 siRNA could reverse the above effect caused by miR-448 inhibitors. MiR-448 targeting SATB1 to counteract the DDP resistance of lung cancer cells via Wnt/β-catenin pathway.

p63-related signaling at a glance

p63 (also known as TP63) is a transcription factor of the p53 family, along with p73. Multiple isoforms of p63 have been discovered and these have diverse functions encompassing a wide array of cell biology. p63 isoforms are implicated in lineage specification, proliferative potential, differentiation, cell death and survival, DNA damage response and metabolism. Furthermore, p63 is linked to human disease states including cancer. p63 is critical to many aspects of cell signaling, and in this Cell science at a glance article and the accompanying poster, we focus on the signaling cascades regulating TAp63 and ΔNp63 isoforms and those that are regulated by TAp63 and ΔNp63, as well the role of p63 in disease.

Special AT-rich Sequence Binding-Protein 1 (SATB1) Correlates with Immune Infiltration in Breast, Head and Neck, and Prostate Cancer

BACKGROUND SATB1 is essential in gene regulation and associates with T cell development. Aberrant SATB1 expression has been reported in various neoplasms. However, correlations between SATB1 and tumor immune infiltration and prognosis in malignancies still remains unclear. MATERIAL AND METHODS We used Oncomine and the Tumor Immune Estimation Resource database to explore the expression of SATB1 in cancers. In addition, Kaplan-Meier plotter, PrognoScan, and Gene Expression Profiling Interactive Analysis were also used to assess the effects of SATB1 on clinical prognosis. Furthermore, correlations between cancer immune infiltration and SATB1 were analyzed via Tumor Immune Estimation Resource. RESULTS The results demonstrated that SATB1 correlates with prognosis in different types of cancers, such as breast invasive carcinoma (BRAC), head and neck cancer (HNSC), and prostate adenocarcinoma (PRAD). Decreased expression of SATB1 was associated with poor overall and progression-free survival of BRAC patients with positive estrogen receptor (ER) as well as mutated TP53. In addition, B cells, CD8+ T cells, CD4+ T cells, macrophages, neutrophils, and dendritic cells infiltration in BRAC, HNSC, and PRAD were also correlated with SATB1 expression level. Moreover, we found strong correlations between SATB1 and various immune markers for BRAC, HNSC, and PRAD. CONCLUSIONS In BRAC, HNSC, and PRAD patients, SATB1 has potential to serve as a prognostic indicator for predicting tumor immune infiltration and prognosis.

SATB1 Expression of Colorectal Adenomatous Polyps is Higher than that of Colorectal Carcinomas

"Special AT-rich sequence-binding protein-1" (SATB1) is a global genome organizer and is found to have effects on carcinogenesis and progression of various malignancies including colorectal carcinoma (CRC). We aimed to investigate the expression of SATB1 in CRC and colorectal adenomatous polyps (CAP), the correlation between clinicopathologic parameters, and overall survival. We examined 227 CRCs and 129 CAPs. SATB1 protein expression was evaluated by immunohistochemistry. We found higher SATB1 expression in adenomatous epithelium than in CRC tissues (55.0% vs. 42.7%, respectively) (P<0.05). None of the adjacent normal colorectal mucosa stained positive in CRC cases, and only one of the adjacent normal mucosa of the CAP cases was positive. SATB1 expression of left-sided CRC was higher than that of right-sided CRC (46.3% vs. 28.6%, respectively) (P<0.05), and SATB1 expression of conventional adenocarcinomas was higher than that of mucinous carcinomas (45.5% vs. 6.3%, respectively) (P<0.05). SATB1 expression was higher in CAPs consisting of high-grade dysplasia than in polyps with low-grade dysplasia (77.8% vs. 51.4%) (P<0.05). SATB1 expression did not correlate with patients' overall survival. In conclusion, due to the higher expression of SATB1 in CAP than in CRC, we think SATB1 may have a role in the early stages of carcinogenesis of CRCs. This is the first study investigating SATB1 expression in CAPs. Besides this is the first report that shows different SATB1 expressions in conventional colorectal adenocarcinoma and mucinous carcinoma, and also in right-sided and left-sided CRC. Our results, with supporting new studies, can provide SATB1 as a possible candidate for targeted therapy for CRC patients.

SATB1 Is a Pivotal Epigenetic Biomarker in Cutaneous T-Cell Lymphomas

The SATB1 protein has been the focus of two recent studies of cutaneous T-cell lymphomas. Fredholm et al. observed a stage-related decrease of SATB1 expression in epidermotropic cutaneous T-cell lymphomas. SATB1 was negatively regulated by STAT5 through microRNA-155, which in turn triggered enhanced expression of T helper type 2 cytokines such as IL-5 and IL-9. In parallel, Sun et al. found that SATB1 expression was up-regulated by promoter demethylation in a subset of cutaneous anaplastic lymphoma and was associated with T helper type 17 polarization in patients with better therapeutic responses.

SATB family chromatin organizers as master regulators of tumor progression

SATB (Special AT-rich binding protein) family proteins have emerged as key regulators that integrate higher-order chromatin organization with the regulation of gene expression. Studies over the past decade have elucidated the specific roles of SATB1 and SATB2, two closely related members of this family, in cancer progression. SATB family chromatin organizers play diverse and important roles in regulating the dynamic equilibrium of apoptosis, cell invasion, metastasis, proliferation, angiogenesis, and immune modulation. This review highlights cellular and molecular events governed by SATB1 influencing the structural organization of chromatin and interacting with several co-activators and co-repressors of transcription towards tumor progression. SATB1 expression across tumor cell types generates cellular and molecular heterogeneity culminating in tumor relapse and metastasis. SATB1 exhibits dynamic expression within intratumoral cell types regulated by the tumor microenvironment, which culminates towards tumor progression. Recent studies suggested that cell-specific expression of SATB1 across tumor recruited dendritic cells (DC), cytotoxic T lymphocytes (CTL), T regulatory cells (Tregs) and tumor epithelial cells along with tumor microenvironment act as primary determinants of tumor progression and tumor inflammation. In contrast, SATB2 is differentially expressed in an array of cancer types and is involved in tumorigenesis. Survival analysis for patients across an array of cancer types correlated with expression of SATB family chromatin organizers suggested tissue-specific expression of SATB1 and SATB2 contributing to disease prognosis. In this context, it is pertinent to understand molecular players, cellular pathways, genetic and epigenetic mechanisms governed by cell types within tumors regulated by SATB proteins. We propose that patient survival analysis based on the expression profile of SATB chromatin organizers would facilitate their unequivocal establishment as prognostic markers and therapeutic targets for cancer therapy.