Special AT-rich Sequence Binding Protein 1 Knockdown Research Articles

Triptolide inhibits esophageal squamous cell carcinoma progression by regulating the circNOX4/miR-153-3p/SATB1 signaling pathway.

To explore the role and mechanism of triptolide in regulating esophageal squamous cell carcinoma (ESCC) progression by mediating the circular RNA (circRNA)-related pathway. The expression levels of circNOX4, miR-153-3p and special AT-rich sequence binding protein-1 (SATB1) were measured by qRT-PCR. Cell proliferation was confirmed by cell counting kit-8 assay and colony formation assay. Flow cytometry was employed to measure cell apoptosis and cell cycle process. Moreover, cell migration and invasion were detected using transwell assay. The protein levels of epithelial-mesenchymal transformation markers and SATB1 were determined by western blot analysis. Furthermore, dual-luciferase reporter assay and RIP assay were performed to confirm the interaction between miR-153-3p and circNOX4 or SATB1. Xenograft tumor models were built to verify the effects of triptolide and circNOX4 on ESCC tumor growth. CircNOX4 was highly expressed in ESCC tissues and cells, and its expression could be reduced by triptolide. Triptolide could inhibit ESCC proliferation, cell cycle process, migration, invasion, EMT process, and promote apoptosis, while these effects were reversed by circNOX4 overexpression. MiR-153-3p could be sponged by circNOX4, and the promotion effect of circNOX4 on the progression of triptolide-treated ESCC cells was abolished by miR-153-3p overexpression. SATB1 was a target of miR-153-3p. Also, SATB1 knockdown reversed the enhancing effect of miR-153-3p inhibitor on the progression of triptolide-treated ESCC cells. Triptolide reduced ESCC tumor growth by regulating the circNOX4/miR-153-3p/SATB1 axis. Triptolide could hinder ESCC progression, which was mainly achieved by regulating the circNOX4/miR-153-3p/SATB1 axis.

Small Interfering RNA-Mediated Knockdown of SATB1 Increases Cell Proliferation through NF-κb Activation in Acute Myeloid Leukemia

Background: Special AT-rich sequence-binding protein 1(SATB1) is a chromatin-remodeling protein that has been shown to regulate gene expressions and aberrant cell growth in different types of cancer. Up-regulation of SATB1 is linked with progression and metastasis of tumors. It is also reported that SATB1 is involved in the differentiation of hematopoietic lineages. However, less is known about the association between SATB1 and hematology malignancy. We previously reported that SATB1 expressions were decreased in T cell leukemia/lymphoma (T-ALL), and knockdown of SATB1 significantly enhanced invasiveness of Jurkat cell through the activation of Wnt/β-catenin signaling pathway in vitro. The contrary roles of SATB1 in solid organ tumors and hematology malignancy may provide hints to study the function of SATB1. Here, we investigated the role of SATB1 in acute myeloid leukemia (AML).Methods: To characterize SATB1 mRNA and protein expression in AML, we performed qRT-PCR and Western blot on peripheral blood mononuclear cells (PBMCs) from 52 newly diagnosed AML patients, as well as AML cell lines NB4, HEL, THP-1 and HL-60. Stable HL-60 cell lines with knockdown of SATB1 by shRNAs sequences (HL-60 SATB1-shRNA1 and HL-60 SATB1-shRNA2) were established. CCK-8 cell proliferation assay and flow cytometric analysis were performed to evaluate the cell proliferation and cell cycle. The invasiveness of HL-60 SATB1-shRNAs and HL-60 CTR cells was analyzed and compared by transwell assay. In order to study the role of SATB1 in vivo, murine model was established using HL-60 SATB1-shRNAs treated nude mice and tumorigenicity was comopared by tumor size. After demonstrating the association between SATB1 knockdown and tumorigenicity in vitro and in vivo, we next investigated NF-κB, AKT and MAPK signaling pathways by western blot.Results:l. SATB1 expression was significantly lower in AML patients than normal controls, which is similar to what we found in T-ALL patients. SATB1 expression was different before and after treatment, especially after complete remission (CR) of AML. Increased SATB1 expression was associated with better clinical outcome. We further investigated the roles of SATB1 on AML cells by shRNAs mediated knockdown of SATB1. Knockdown of SATB1 promoted the proliferation of HL-60 SATB1 shRNA1 cells and HL-60 SATB1 shRNA2 cells compared to the control. However, the transwell assay did not show increased invasiveness in SATB1 depleted HL-60 cells. The in vivo experiment showed that tumor size and weight in SATB1 knockdown mice were significantly increased compared to the control mice. In the mechanism study, we investigated NF-κB, AKT and MAPK signaling pathways by western blot. We found that the expression of NF-κB p65 in HL60 SATB1-shRNAs cells was increased, which suggested that SATB1 regulated AML cell growth via the activation of NF-κB signaling pathway.Conclusions: Impairment of SATB1 is associated with AML. SATB1 expressions were decreased in AML. Knockdown of SATB1 promoted cell proliferation and tumorigenicity of AML via the activation of NF-κB signaling pathway. DisclosuresNo relevant conflicts of interest to declare.

SATB1 Knockdown Inhibits Proliferation and Invasion and Decreases Chemoradiation Resistance in Nasopharyngeal Carcinoma Cells by Reversing EMT and Suppressing MMP-9.

Background: Special AT-rich sequence binding protein 1 (SATB1) is a chromatin organizer and transcriptional regulator which regulate numerous cellular processes through effects on multiple gene expression. SATB1 is associated with drug resistance in several cancers. Whether SATB1 involves radiation resistance in nasopharyngeal carcinoma (NPC) and underlying mechanism of SATB1 to participate in chemoradiotherapy resistance in NPC have not been elaborated.Methods: Chemoradioresistant NPC cell lines 5-8F/DDP (cisplatin) and 5-8F/R (radiation) were developed from 5-8F cell line. The expressions of SATB1, MMP-9 and EMT markers (Vimentin and E-cadherin) in these cell lines were examined by reverse transcription-quantitative (RT-q) PCR and western blot (WB) analysis. Cell viabilities of 5-8F/DDP treated with various concentrations of DDP and 5-8F/R irradiated with various doses of X-ray at the indicated time were investigated by MTT test. SATB1 was silenced in 5-8F/DDP and 5-8F/R cells by short hairpin RNA, and then the expressions of SATB1, MMP-9, Vimentin and E-cadherin were evaluated by RT-qPCR and WB analysis; the abilities of cell proliferation and invasion were assessed using MTT and transwell assays, respectively. Drug and radiation resistance assays were performed after SATB1 knockdown and cell viability was detected by MTT method.Results: SATB1, MMP-9 and Vimentin were markedly upregulated in 5-8F/DDP and 5-8F/R cells compared with 5-8F cell, whereas E-cadherin was obviously downregulated. 5-8F/DDP and 5-8F/R cells displayed drug and radiation resistance to DDP or X-irradiation, respectively, while DDP or X-irradiation inhibited 5-8F cell viability in a time- and dose-dependent manner. Subsequently, knockdown of SATB1 resulted in decreased MMP-9 and Vimentin expression and increased E-cadherin expression in 5-8F/DDP and 5-8F/R. Furthermore, silencing of SATB1 suppressed proliferative and invasive abilities of 5-8F/DDP and 5-8F/R cells. Additionally, SATB1 knockdown reduced drug resistance of 5-8F/DDP cell to DDP and decreased radiation resistance of 5-8F/R cell to X-ray.Conclusion: These results suggest that high expression of SATB1 plays an important role in the malignant behavior of NPC and leads to X-radiation and drug resistance in NPC through promoting EMT process and enhancing MMP-9 expression. SATB1 may be a promising therapeutic target for aggressive and chemoradiation resistant NPC.

SATB1 as oncogenic driver and potential therapeutic target in head & neck squamous cell carcinoma (HNSCC)

The Special AT-rich sequence binding protein 1 (SATB1) is a genome organizer protein that controls gene expression of numerous genes by regulating chromatin architecture and targeting chromatin-remodeling/-modifying enzymes onto specific chromatin regions. SATB1 is overexpressed in various tumors. In head and neck squamous cell carcinoma (HNSCC), SATB1 upregulation is correlated with TNM classification, metastasis, poor prognosis and reduced overall survival. In this paper, we comprehensively analyze cellular and molecular effects of SATB1 in a large set of primary cell lines from primary HNSCC or metastases, using RNAi-mediated knockdown in vitro and, therapeutically, in tumor xenograft mouse models in vivo. In a series of 15 cell lines, major differences in SATB1 levels are observed. In various 2-D and 3-D assays, growth inhibition upon efficient siRNA-mediated SATB1 knockdown depends on the cell line rather than initial SATB1 levels. Inhibitory effects are found to be based on cell cycle deceleration, apoptosis induction, decreased HER3 and Heregulin A&B expression, and effects on EMT genes. In vivo, systemic treatment of tumor xenograft-bearing mice with siRNAs formulated in polymeric nanoparticles inhibits tumor growth of two HNSCC xenograft models, resulting from therapeutic SATB1 reduction and concomitant decrease of proliferation and induction of apoptosis. In conclusion, SATB1 represents a promising target in HNSCC, affecting crucial cellular processes and molecular pathways.

Abstract 2100: Resistance of gastric carcinoma cells towards c-met inhibition is mediated by compensatory HER3 upregulation involving SATB1 and PKC

Abstract Introduction: In patients with gastric cancer expressing high levels of c-met, inhibitors of the receptor tyrosine kinase (RTK) c-met are explored as targeted therapeutics. Unfortunately, clinical trials have failed to improve survival so far. This might be due to compensatory stimulation of other oncogenic RTKs. Here, we highlight the role of HER3 upregulation and its specific stimulation as resistance mechanism. On the mechanistic side, we demonstrate the genome regulator special AT-rich sequence-binding protein-1 (SATB1) as a critical mediator of this HER3 upregulation, with further manipulation being executed by contrary roles of Protein kinase C (PKC) and Phosphatidylinositol 3-kinase (PI3K). Methods: We used gastric cancer cell lines with a c-met amplification and evaluated the impact of pharmacological or siRNA-mediated c-met inhibition on cellular proliferation and survival. Moreover, we analyzed the expression of HER family receptors after inhibitor treatment. Furthermore, we used transient knockdown of SATB1 as well as inhibitors of PKC and PI3K to gain insight into signaling mechanisms. Results: The use of c-met kinase inhibitors or RNAi-induced downregulation of c-met led to a complete disruption of cellular proliferation. Without addition of c-met inhibitors, the investigated gastric cancer cells expressed HER1, HER2, and HER3 receptors, but no HER3 ligands. After pretreatment with c-met inhibitors, HER3 expression was markedly upregulated. Treatment of gastric cancer cells with the HER3 ligand beta-heregulin, usually secreted by cancer associated fibroblasts, partially reversed the anti-proliferative effects of c-met inhibitors. The induction of HER3 was reduced after pretreating cells with SATB1 siRNA. SATB1 is a known regulator of HER receptor expression in other tumor entities. The regulatory functions of SATB1 can be further modulated by phosphorylation via PKC or PI3K. Therefore, we investigated the effect of PKC and PI3K inhibition on HER3 induction. Of note, PKC inhibition markedly reduced HER3 upregulation, whereas PI3K inhibitors even increased HER3 levels. Conclusions: PKC and SATB1 are involved in the compensatory upregulation of HER3 upon c-met inhibition. Since this represents a critical resistance factor, interference with PKC and SATB1 signaling is a potential avenue to prevent resistance towards c-met inhibitors in gastric cancer. Citation Format: Robert Jenke, Thomas Büch, Miriam Rein, Stefanie Müller, Florian Lordick, Achim M. Aigner. Resistance of gastric carcinoma cells towards c-met inhibition is mediated by compensatory HER3 upregulation involving SATB1 and PKC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2100.

SATB1 promotes epithelial-mesenchymal transition via Notch signaling pathway in colorectal cancer

Epithelial-mesenchymal transition (EMT) is essential for initiation of colorectal cancer (CRC) metastasis, but the diver proteins of EMT remain unclear. Special AT-rich sequence-binding protein 1 (SATB1) was found to be overexpressed in CRC cell lines, and its expression level was positively correlated with CRC progression. Strikingly, EMT process was regulated by SATB1, as SATB1 overexpression upregulated E-cadherin and SATB1 knockdown inhibited N-cadherin cell models. Mechanistically, SATB1 promoted EMT-mediated CRC metastasis via activation of Notch signaling pathway. Taken together, SATB1 plays a vital role in CRC metastasis and may act as a novel prognostic biomarker and a promising therapeutic target for CRC.

Silencing SATB1 overcomes temozolomide resistance by downregulating MGMT expression and upregulating SLC22A18 expression in human glioblastoma cells.

Glioblastoma multiforme (GBM) is the most common malignant tumor of the central nervous system and has a very poor prognosis. Currently, patients were treated by resection followed by radiotherapy plus concurrent temozolomide (TMZ) chemotherapy. However, many patients are resistant to TMZ-induced DNA damage because of upregulated expression of the DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT). In this study, upregulation of SATB1 and MGMT, and downregulation of SLC22A18 resulted in acquisition of TMZ resistance in GBM U87 cells. Inactivation of special AT-rich sequence-binding protein 1 (SATB1) using short hairpin RNA (shRNA) downregulated MGMT expression and upregulated solute carrier family 22 member 18 (SLC22A18) expression in GBM cells. This suggested SATB1-mediated posttranscriptional regulation of the MGMT and SLC22A18 protein levels. Immunohistochemical analysis of malignant glioma specimens demonstrated a significant positive correlation between the levels of MGMT and SATB1, and a negative correlation between the levels of SLC22A18 and SATB1. Importantly, in recurrent, compared with the primary, lesions in 15 paired identical tumors, the SATB1 and MGMT protein levels were increased and the SLC22A18 levels were decreased. Finally, in TMZ-resistant GBM, SATB1 knockdown enhanced TMZ efficacy. Consequently, SATB1 inhibition might be a promising strategy combined with TMZ chemotherapy to treat TMZ-resistant GBM.

The role of SATB1 in HTR8/SVneo cells and pathological mechanism of preeclampsia

Objective: Special AT-rich sequence binding protein 1 (SATB1) play potential roles in invasion and metastasis of tumor cells, and involves in human placental and fetal development. The objective of this study is to explore the role of SATB1 in migration and invasion of trophoblast and the potential mechanism.Methods: Human placental tissues from first trimester, second trimester, term, and preeclampsia (PE) pregnancies were used to detect the expression and subcellular location of SATB1 and β-catenin. The human trophoblast cell line HTR8/SVneo, which was treated with hypoxia/re-oxygenation (H/R), lithium chloride (LiCl) or SATB1-siRNA to investigate the role of SATB1 and β-catenin signaling in human trophoblast function.Results: We observed that SATB1 specifically localized within trophoblast cells of placenta tissues. Gradually reduced expression of SATB1 was observed during gestation, and lower expression were detected in placenta of PE compared with normal pregnancy. Moreover, the expression of SATB1 was decreased in H/R-treated HTR8/Svneo cells and villous explants. The Wnt/β-catenin signaling pathway interacted with SATB1 expression and H/R treatment resulted in Wnt pathway inhibition in trophoblast, while lithium chloride (LiCl) treatment enhanced H/R-exposed HTR8/SVneo migration and invasion. Knockdown of SATB1 significantly reduced the level of β-catenin and the migratory and invasive abilities of trophoblast.Conclusions: Our data suggested that oxidative stress reduced SATB1 leading to inhibition of Wnt/β-catenin, and participate in the subdued migration and invasion of trophoblast, which indicated a potential pathological mechanism of PE.

SATB1 promotes epithelial-mesenchymal transition and metastasis in prostate cancer.

Special AT-rich sequence-binding protein-1 (SATB1) is associated with cancer progression and poor clinical outcome. The present study aims to evaluate whether SATB1 affects the biological behaviors of prostate cancer (PCa), and furthermore, to elucidate whether this effect works through the epithelial-mesenchymal transition (EMT) pathway. Firstly, the expression of SATB1 was investigated in a series of PCa tissues as well as in a panel of PCa cell lines. Cell proliferation, migration and invasion were evaluated in SATB1 knockdown and overexpressed PCa cell lines by MTT and Transwell assays. The results showed that the expression of SATB1 was markedly upregulated in PCa tissues and all PCa cell lines (P<0.001). Ectopic expression of SATB1 promoted PCa cell proliferation and migration. Knockdown of SATB1 repressed the ability of cell proliferation and migration of PCa cells. In addition, inhibition of SATB1 could reverse the EMT processes through upregulation of E-cadherin and downregulation of vimentin. The present study provided evidence that SATB1 may act as a potential therapeutic target in PCa patients.

Analysis of cellular and molecular antitumor effects upon inhibition of SATB1 in glioblastoma cells

BackgroundThe Special AT-rich Sequence Binding Protein 1 (SATB1) regulates the expression of many genes by acting as a global chromatin organizer. While in many tumor entities SATB1 overexpression has been observed and connected to pro-tumorigenic processes, somewhat contradictory evidence exists in brain tumors with regard to SATB1 overexpression in glioblastoma and its association with poorer prognosis and tumor progression. On the functional side, initial data indicate that SATB1 may be involved in several tumor cell-relevant processes.MethodsFor the detailed analysis of the functional relevance and possible therapeutic potential of SATB1 inhibition, we employ transient siRNA-mediated knockdown and comprehensively analyze the cellular and molecular role of SATB1 in glioblastoma.ResultsIn various cell lines with different SATB1 expression levels, a SATB1 gene dose-dependent inhibition of anchorage-dependent and –independent proliferation is observed. This is due to cell cycle-inhibitory and pro-apoptotic effects of SATB1 knockdown. Molecular analyses reveal SATB1 knockdown effects on multiple important (proto-) oncogenes, including Myc, Bcl-2, Pim-1, EGFR, β-catenin and Survivin. Molecules involved in cell cycle, EMT and cell adhesion are affected as well. The putative therapeutic relevance of SATB1 inhibition is further supported in an in vivo tumor xenograft mouse model, where the treatment with polymeric nanoparticles containing SATB1-specific siRNAs exerts antitumor effects.ConclusionOur results demonstrate that SATB1 may represent a promising target molecule in glioblastoma therapy whose inhibition or knockdown affects multiple crucial pathways.

Special AT-rich Sequence-binding Protein 1 (SATB1) Functions as an Accessory Factor in Base Excision Repair

Base excision repair is initiated by DNA glycosylases that recognize specific altered bases. DNA glycosylases for oxidized bases carry both a glycosylase activity that removes the faulty base and an apyrimidinic/apurinic lyase activity that introduces a single-strand DNA incision. In particular, the CUT domains within the CUX1 and CUX2 proteins were recently shown to interact with the 8-oxoguanine (8-oxoG) DNA glycosylase and stimulate its enzymatic activities. SATB1, which contains two CUT domains, was originally characterized as a T cell-specific genome organizer whose aberrant overexpression in breast cancer can promote tumor progression. Here we investigated the involvement of SATB1 in DNA repair. SATB1 knockdown caused a delay in DNA repair following exposure to H2O2, an increase in OGG1-sensitive oxidized bases within genomic DNA, and a decrease in 8-oxoG cleavage activity in cell extracts. In parallel, we observed an increase in phospho-CHK1 and γ-H2AX levels and a decrease in DNA synthesis. Conversely, ectopic expression of SATB1 accelerated DNA repair and reduced the levels of oxidized bases in genomic DNA. Moreover, an enhanced GFP-SATB1 fusion protein was rapidly recruited to laser microirradiation-induced DNA damage. Using purified proteins, we showed that SATB1 interacts directly with OGG1, increases its binding to 8-oxoG-containing DNA, promotes Schiff base formation, and stimulates its glycosylase and apyrimidinic/apurinic lyase enzymatic activities. Structure/function analysis demonstrated that CUT domains, but not the homeodomain, are responsible for the stimulation of OGG1. Together, these results identify another CUT domain protein that functions both as a transcription factor and an accessory factor in base excision repair.

SATB1 is a potential therapeutic target in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary malignant tumor of the liver with a poor prognosis. Upregulation of special AT-rich sequence-binding protein 1 (SATB1) promotes tumor progression. However, little is known about the role of SATB1 in ICC tumorigenesis. We firstly investigated the expression of SATB1 in 88 cases of ICC by immunohistochemistry (IHC), QRT-PCR, and western blot. Meanwhile, we constructed stably knockdown (shRNA) of SATB1 in ICC cell lines to evaluate the effects of SATB1 on the ability of cell proliferation and invasion by MTT and transwell invasion assay. Our result showed that SATB1 was overexpressed in ICC tissues samples. Knockdown of SATB1 could inhibit ICC cell proliferation, and suppress ICC cell invasion of ICC cell lines. In addition, the depletion of SATB1 expression suppressed the MYC levels in vitro. Our results highlight the significance of SATB1 in ICC and suggest that SATB1 could be a promising therapy target and a potential biomarker for prognosis in ICC patients.

Special AT-rich sequence binding protein 1 expression correlates with response to preoperative radiotherapy and clinical outcome in rectal cancer

Our recent study showed the important role of special AT-rich sequence binding protein 1 (SATB1) in the progression of human rectal cancer. However, the value of SATB1 in response to radiotherapy (RT) for rectal cancer hasn't been reported so far. Here, SATB1 was determined using immunohistochemistry in normal mucosa, biopsy, primary cancer, and lymph node metastasis from 132 rectal cancer patients: 66 with and 66 without preoperative RT before surgery. The effect of SATB1 knockdown on radiosensitivity was assessed by proliferation-based assay and clonogenic assay. The results showed that SATB1 increased from normal mucosa to primary cancer, whereas it decreased from primary cancer to metastasis in non-RT patients. SATB1 decreased in primary cancers after RT. In RT patients, positive SATB1 was independently associated with decreased response to preoperative RT, early time to metastasis, and worse survival. SATB1 negatively correlated with ataxia telangiectasia mutated (ATM) and pRb2/p130, and positively with Ki-67 and Survivin in RT patients, and their potential interaction through different canonical pathways was identified in network ideogram. Taken together, our findings disclose for the first time that radiation decreases SATB1 expression and sensitizes cancer cells to confer clinical benefit of patients, suggesting that SATB1 is predictive of response to preoperative RT and clinical outcome in rectal cancer.

SATB1 overexpression regulates the development and progression in bladder cancer through EMT.

The global gene regulator Special AT-rich sequence-binding protein-1 (SATB1) has been reported to induce EMT-like changes and be associated with poor clinical outcome in several cancers. This study aims to evaluate whether SATB1 affects the biological behaviors of bladder transitional cell carcinoma (BTCC) and further elucidate if this effect works through an epithelial-mesenchymal transition (EMT) pathway. The expression of SATB1, E-cadherin (epithelial markers), vimentin (mesenchymal markers) in BTCC tissues and adjacent noncancerous tissues, as well as in two cell lines of bladder cancer were investigated. Whether the SATB1 expression is associated with clinicopathological factors or not was statistically analyzed. Cell invasion and migration, cell cycle, cell proliferation and apoptosis were evaluated in SATB1 knockdown and overexpressed cell lines. Our results showed that the expression of SATB1 was remarkably up-regulated both in BTCC tissues and in bladder cancer cell lines with high potential of metastasis. The results were also associated with EMT markers and poor prognosis of BTCC patients. Moreover, SATB1 induced EMT processes through downregulation of E-cadherin, upregulation of E-cadherin repressors (Snail, Slug and vimentin). SATB1 also promoted cell cycle progression, cell proliferation, cell invasion and cell migration, but did not alter cell survival. In conclusion, our results suggest that SATB1 plays a crucial role in the progression of bladder cancer by regulating genes controlling EMT processes. Further, it may be a novel therapeutic target for aggressive bladder cancers.

Special AT-rich sequence-binding protein-1 participates in the maintenance of breast cancer stem cells through regulation of the Notch signaling pathway and expression of Snail1 and Twist1.

The stem cell populations in cancerous tissues and cell lines vary widely and are often associated with aggressive cases of breast cancer. Despite research on the topic, the mechanism underlying the regulation of the breast cancer stem cell (BCSC) population within tumors remains to be fully elucidated. To investigate the function of special AT-rich sequence-binding protein-1 (SATB1) in the maintenance of the BCSC population, SATB1 was overexpressed with lentivirus in MCF-7 cells or knocked down with shRNA-lentivirus in BT-549 cells. The effects of SATB1 overexpression or knockdown on mammosphere formation, the size of the of BCSC population, cell invasion and tumorigenesis were investigated. Activation of the Notch signaling pathway and expression of Snail1 and Twist1 were also examined in the cells. Overexpression of SATB1 in MCF-7 cells was observed to increase mammosphere formation, the size of the BCSC population, cell invasion and tumorigenesis, accompanied by an increase in the activation of Notch signaling and expression levels of Snail1 and Twist1. Conversely, knockdown of SATB1 in BT-549 cells produced the opposite effects. The results indicated that expression of SATB1 may increase the size of the BCSC population via the activation of the Notch signaling pathway and by increasing expression levels of Snail1 and Twist1.

Decreased SATB1 Expression in ALT and Promoted Invasion of Jurkat Cell in Vitro

BACKGROUND: Special AT-rich sequence-binding protein-1 (SATB1) is critical for genome organizer that reprograms chromatin organization and transcription profiles, and associated with tumor growth and metastasis in several cancer types cancer. However, their expression patterns and function values for adult T-cell leukemia (ALT) are still largely unknown.METHODS: Expression of SATB1 in normal and ALT peripheral blood leucocytes (n=50 for normal, n=30 for ALT) were evaluated by RT-qPCR in mRNA level. Expression of protein SATB1 in leukemia cell lines were evaluated by Weston Blot.SATB1-shRNA was constructed in psuper-retro-puro retrovirus vector. Jurkat-SATB1-sh and control stable cell lines were established after virus infection and puromycin selection. Cellular proliferation and invasion of Jurkat-ctr and SATB1 knockdown Jurkat cells were evaluated by CCK-8 kit and transwell matrigel invasion assay, respectively.RESULTS: SATB1 mRNA expression was decreased in ALT (p<0.001) compared with normal peripheral blood leucocytes cells. SATB1 protein expression in Jurkat cell was higher than other leukemia cell lines. SATB1-shRNA was constructed successfully. Weston Blot show Jurkat-SATB1-sh and control stable cell lines were established successfully. Knockdown of SATB1 expression significantly enhanced invasion of Jurkat cell in vitro but no effect in proliferationCONCLUSIONS: Decreased expression of SATB1 in ALT was associated with cell invasion. DisclosuresNo relevant conflicts of interest to declare.

Expression of SATB1 promotes the growth and metastasis of colorectal cancer.

Special AT-rich sequence-binding protein-1 (SATB1) has been identified as a genome organizer that reprograms chromatin organization and transcription profiles. SATB1 promotes tumor growth and metastasis in breast cancer and is associated with poor prognosis in several cancer types. The association between SATB1 and colorectal cancer (CRC) has not been studied intensively. Therefore, this study aimed to investigate the effect of SATB1 on CRC growth and metastasis in vitro and in vivo and its correlation with overall survival and clinicopathological factors in CRC patients. Stable SATB1 knockdown and SATB1-overexpressing cell lines were established. SATB1 knockdown decreased cell growth, colony formation, migration, and invasion and increased apoptosis in CRC cells in vitro (p<0.05), whereas SATB1 overexpression had the opposite effect. SATB1 overexpression increased tumor growth and metastasis to lung and liver in vivo by using xenograft animal models (p<0.05). Thus, SATB1 promoted an aggressive CRC phenotype in vitro and in vivo. Immunohistochemical analysis of 560 CRC specimens showed that SATB1 expression was significantly higher in CRC tissues than in matched non-tumor mucosa (p<0.001). In addition, SATB1 expression was significantly higher in patients with poorly differentiated tumors, higher invasion depth, distant metastasis, and advanced TNM stage. SATB1-positive patients had a poorer prognosis than SATB1-negative patients, and SATB1 was identified as an independent prognostic factor for CRC (p = 0.009). Strikingly, we also evaluated SATB2 expression in CRC and found that SATB2 was more abundantly expressed in non-cancerous mucosa compared to colorectal cancer tissues (p<0.001). However, SATB2 expression had no influence on prognosis of CRC patients (p = 0.836). SATB1 expression was significantly associated with shorter survival time either in SATB2-positive patients or in SATB2-negative patients (p<0.001). In conclusion, our findings indicated an important role for SATB1 in CRC tumorigenesis and metastasis. Therefore, SATB1 may represent an important prognostic biomarker and therapeutic target for CRC.

Overexpression of SATB1 is associated with biologic behavior in human renal cell carcinoma.

Special AT-rich sequence-binding protein-1 (SATB1) has been reported to be aberrantly expressed in various cancers and correlated with the malignant behavior of cancer cells. However, the function of SATB1 in RCC remains unclear. With the combination of immunohistochemistry, western blotting, immunofluorescence, qRT-PCR, and cell proliferation, migration and invasion assays, we found that levels of SATB1 mRNA and protein were dramatically increased in human ccRCC tissues (P<0.001 for both), and upregulation of SATB1 was significantly associated with depth of invasion (P<0.001), lymph node status (P = 0.001) and TNM stage (P = 0.009). SATB1 knockdown inhibited the proliferation, migration and invasion of 786-O cells, whereas SATB1 overexpression promoted the growth and aggressive phenotype of ACHN cells in vitro. Furthermore, SATB1 expression was positively correlated with ZEB2 expression (P = 0.013), and inversely linked to levels of SATB2 and E-cadherin (P = 0.005 and P<0.001, respectively) in ccRCC tissues. Our data provide a basis for the concept that overexpression of SATB1 may play a critical role in the acquisition of an aggressive phenotype for RCC cells through EMT, providing new insights into the significance of SATB1 in invasion and metastasis of ccRCC, which may contribute to fully elucidating the exact mechanism of development and progression of RCC.

Inhibition of human glioma U251 cells growth in vitro and in vivo by hydroxyapatite nanoparticle-assisted delivery of short hairpin RNAs against SATB1

Special AT-rich sequence-binding protein-1 (SATB1) has been reported to be over-expressed in many human tumors and knockdown of SATB1 can inhibit tumor growth. The present study was designed to determine the role of SATB1 in the growth of human glioma U251 cells using the plasmid-based SATB1 short hairpin RNA (shRNA) delivered by hydroxyapatite nanoparticles in vitro and in vivo. The in vitro growth, invasion and angiogenesis assays of human glioma U251 cells were done. U251 cells tumor blocks were transplanted into the nude mice. CaCl2-modified hydroxyapatite nanoparticles carrying shRNA-SATB1 plasmids were injected into the tumors. The apoptosis of the tumor U251 cells was examined with TUNEL assay and flow cytometer (FCM). The tumor growth and immunohistochemistry were measured. The expression level of SATB1 mRNA was investigated by RT-PCR. The expression levels of SATB1, Cyclin D1, MMP-2, VEGF, Bax and Caspase-9 protein were determined by western blot analysis. The results showed that hydroxyapatite nanoparticles-delivered shRNA-SATB1 could significantly inhibit the growth, invasion and angiogenesis of U251 cells in vitro and the growth of U251 cells in vivo. FCM results showed that Nano HAP-shRNA-SATB1-induced apoptosis (up to 67.8%). SATB1 expression was strongly down-regulated in the tumor U251 cells. Cyclin D1, MMP-2 and VEGF were also down-regulated in the tumor tissues that also displayed significant increased in Bax expression and Caspase-9 activity. These results show that Nano HAP-shRNA-SATB1 can inhibit the growth of human glioma U251 cells in vitro and in vivo, and hydroxyapatite nanoparticles can be used for the in vitro and in vivo delivery of plasmid-based shRNAs into U251 cells.

Expression and biological roles of SATB1 in human bladder cancer

Special AT-rich sequence-binding protein-1 (SATB1) has been recently reported to be overexpressed in various cancers and associate with the malignant behavior of cancer cells. However, the expression and potential roles of SATB1 in bladder cancer remains unclear. In the present study, SATB1 expression was analyzed in 85 archived bladder cancer specimens using immunohistochemistry and the correlations between SATB1 expression and clinicopathological parameters were evaluated. To further explore the biological functions of SATB1 in bladder cancer, siRNA knockdown was performed in 5637 and T24 bladder cancer cell lines. We then carried out CCK8 assay and examined cisplatin-induced apoptosis to address the roles of SATB1 in proliferation and apoptosis. We found that SATB1 was overexpressed in 33 of 85 (38.8 %) bladder cancer specimens. SATB1 overexpression associated with tumor grade (p = 0.002) and tumor stage (p = 0.027). SATB1 depletion in 5637 and T24 cells decreased cell proliferation while upregulating cisplatin-induced apoptosis. Further study demonstrated that SATB1 knockdown decreased cyclin D1 and cyclin E expression and upregulated caspase3 cleavage. In conclusion, SATB1 is overexpressed in bladder cancer and regulates malignant cell growth and apoptosis, which makes SATB1 a therapeutic target candidate for bladder cancer.