SATB1 is overexpressed in metastatic prostate cancer and promotes prostate cancer cell growth and invasion

SATB1, senescence and senescence-related diseases

Aging leads to an accumulation of cellular mutations and damage, increasing the risk of senescence, apoptosis, and malignant transformation. Cellular senescence, which is pivotal in aging, acts as both a guard against cellular transformation and as a check against cancer progression. It is marked by stable cell cycle arrest, widespread macromolecular changes, a pro-inflammatory profile, and altered gene expression. However, it remains to be determined whether these differing subsets of senescent cells result from unique intrinsic programs or are influenced by their environmental contexts. Multiple transcription regulators and chromatin modifiers contribute to these alterations. Special AT-rich sequence-binding protein 1 (SATB1) stands out as a crucial regulator in this process, orchestrating gene expression by structuring chromatin into loop domains and anchoring DNA elements. This review provides an overview of cellular senescence and delves into the role of SATB1 in senescence-related diseases. It highlights SATB1's potential in developing antiaging and anticancer strategies, potentially contributing to improved quality of life and addressing aging-related diseases.

Purine-Rich Element Binding Protein Alpha, a Nuclear Matrix Protein, Has a Role in Prostate Cancer Progression

Solid tumors as well as leukemias and lymphomas show striking changes in nuclear structure including nuclear size and shape, the number and size of nucleoli, and chromatin texture. These alterations have been used in cancer diagnosis and might be related to the altered functional properties of cancer cells. The nuclear matrix (NM) represents the structural composition of the nucleus and consists of nuclear lamins and pore complexes, an internal ribonucleic protein network, and residual nucleoli. In the nuclear microenvironment, the NM is associated with multi-protein complexes, such as basal transcription factors, signaling proteins, histone-modifying factors, and chromatin remodeling machinery directly or indirectly through scaffolding proteins. Therefore, alterations in the composition of NM could result in altered DNA topology and changes in the interaction of various genes, which could then participate in a cascade of the cancer process. Using an androgen-sensitive prostate cancer cell line, LNCaP, and its androgen-independent derivative, LN96, conventional 2D-proteomic analysis of the NM proteins revealed that purine-rich element binding protein alpha (PURα) was detected in the NM proteins and differentially expressed between the cell lines. In this article, we will review the potential role of the molecule in prostate cancer.

Adaptive and non-adaptive gene expression responses in prostate cancer during androgen deprivation

Androgen deprivation therapy is the cornerstone treatment of advanced prostate cancer. Eventually prostate cancer cells overcome androgen deprivation therapy, giving rise to castration resistant prostate cancer (CRPC) characterized by increased androgen receptor (AR) activity. Understanding the cellular mechanisms leading to CRPC is needed for development of novel treatments. We used long-term cell cultures to model CRPC; a testosterone-dependent cell line (VCaP-T) and cell line adapted to grow in low testosterone (VCaP-CT). These were used to uncover persistent and adaptive responses to testosterone level. RNA was sequenced to study AR-regulated genes. Expression level changed due to testosterone depletion in 418 genes in VCaP-T (AR-associated genes). To evaluate significance for CRPC growth, we compared which of them were adaptive i.e., restored expression level in VCaP-CT. Adaptive genes were enriched to steroid metabolism, immune response and lipid metabolism. The Cancer Genome Atlas Prostate Adenocarcinoma data were used to assess the association with cancer aggressiveness and progression-free survival. Expressions of 47 AR-associated or association gaining genes were statistically significant markers for progression-free survival. These included genes related to immune response, adhesion and transport. Taken together, we identified and clinically validated multiple genes being linked with progression of prostate cancer and propose several novel risk genes. Possible use as biomarkers or therapeutic targets should be studied further.

3D Genome Organization as an Epigenetic Determinant of Transcription Regulation in T Cells

In the heart of innate and adaptive immunity lies the proper spatiotemporal development of several immune cell lineages. Multiple studies have highlighted the necessity of epigenetic and transcriptional regulation in cell lineage specification. This mode of regulation is mediated by transcription factors and chromatin remodelers, controlling developmentally essential gene sets. The core of transcription and epigenetic regulation is formulated by different epigenetic modifications determining gene expression. Apart from “classic” epigenetic modifications, 3D chromatin architecture is also purported to exert fundamental roles in gene regulation. Chromatin conformation both facilitates cell-specific factor binding at specified regions and is in turn modified as such, acting synergistically. The interplay between global and tissue-specific protein factors dictates the epigenetic landscape of T and innate lymphoid cell (ILC) lineages. The expression of global genome organizers such as CTCF, YY1, and the cohesin complexes, closely cooperate with tissue-specific factors to exert cell type-specific gene regulation. Special AT-rich binding protein 1 (SATB1) is an important tissue-specific genome organizer and regulator controlling both long- and short-range chromatin interactions. Recent indications point to SATB1’s cooperation with the aforementioned factors, linking global to tissue-specific gene regulation. Changes in 3D genome organization are of vital importance for proper cell development and function, while disruption of this mechanism can lead to severe immuno-developmental defects. Newly emerging data have inextricably linked chromatin architecture deregulation to tissue-specific pathophysiological phenotypes. The combination of these findings may shed light on the mechanisms behind pathological conditions.

SATB1, genomic instability and Gleason grading constitute a novel risk score for prostate cancer

Current prostate cancer risk classifications rely on clinicopathological parameters resulting in uncertainties for prognostication. To improve individual risk stratification, we examined the predictive value of selected proteins with respect to tumor heterogeneity and genomic instability. We assessed the degree of genomic instability in 50 radical prostatectomy specimens by DNA-Image-Cytometry and evaluated protein expression in related 199 tissue-microarray (TMA) cores. Immunohistochemical data of SATB1, SPIN1, TPM4, VIME and TBB5 were correlated with the degree of genomic instability, established clinical risk factors and overall survival. Genomic instability was associated with a GS ≥ 7 (p = 0.001) and worse overall survival (p = 0.008). A positive SATB1 expression was associated with a GS ≤ 6 (p = 0.040), genomic stability (p = 0.027), and was a predictor for increased overall survival (p = 0.023). High expression of SPIN1 was also associated with longer overall survival (p = 0.048) and lower preoperative PSA-values (p = 0.047). The combination of SATB1 expression, genomic instability, and GS lead to a novel Prostate Cancer Prediction Score (PCP-Score) which outperforms the current D’Amico et al. stratification for predicting overall survival. Low SATB1 expression, genomic instability and GS ≥ 7 were identified as markers for poor prognosis. Their combination overcomes current clinical risk stratification regimes.

Prognostic Significance of TLR2, SMAD3 and Localization-dependent SATB1 in Stage I and II Non-Small-Cell Lung Cancer Patients

This study aimed to explore the prognostic value of SATB1, SMAD3, and TLR2 expression in non-small-cell lung carcinoma patients with clinical stages I-II. To investigate, we evaluated immunohistochemical staining to each of these markers using tissue sections from 69 patients from our cohort and gene expression data for The Cancer Genome Atlas (TCGA) cohort. We found that, in our cohort, high expression levels of nuclear SATB1ⁿ and SMAD3 were independent prognostic markers for better overall survival (OS) in NSCLC patients. Interestingly, expression of cytoplasmic SATB1^c exhibited a significant but inverse association with survival rate, and it was an independent predictor of unfavorable prognosis. Likewise, TLR2 was a negative outcome biomarker for NSCLC even when adjusting for covariates. Importantly, stratification of NSCLCs with respect to combined expression of the three biomarkers allowed us to identify subgroups of patients with the greatest difference in duration of survival. Specifically, expression profile of SATB1^n-high/SMAD3^high/TLR2^low was associated with the best OS, and it was superior to each single protein alone in predicting patient prognosis. Furthermore, based on the TCGA dataset, we found that overexpression of SATB1 mRNA was significantly associated with better OS, whereas high mRNA levels of SMAD3 and TLR2 with poor OS. In conclusion, the present study identified a set of proteins that may play a significant role in predicting prognosis of NSCLC patients with clinical stages I-II.

Co-Adjuvant Therapy Efficacy of Catechin and Procyanidin B2 with Docetaxel on Hormone-Related Cancers In Vitro

Prostate (PC) and breast cancer (BC) are heterogeneous hormonal cancers. Treatment resistance and adverse effects are the main limitations of conventional chemotherapy treatment. The use of sensitizing agents could improve the effectiveness of chemotherapeutic drugs as well as obviate these limitations. This study analyzes the effect of single catechin (CAT), procyanidin B2 (ProB2) treatment as well as the co-adjuvant treatment of each of these compounds with docetaxel (DOCE). We used PC- and BC-derived cell lines (PC3, DU-145, T47D, MCF-7 and MDA-MB-231). The short and long-term pro-apoptotic, anti-proliferative and anti-migratory effects were analyzed. RT-qPCR was used to discover molecular bases of the therapeutic efficacy of these compounds. ProB2 treatment induced a two- to five-fold increase in anti-proliferative and pro-apoptotic effects compared to single DOCE treatment, and also had a more sensitizing effect than DOCE on DU145 cells. Regarding BC cells, ProB2- and CAT-mediated sensitization to DOCE anti-proliferative and pro-apoptotic effects was cell-independent and cell-dependent, respectively. Combined treatment led to high-efficacy effects on MCF-7 cells, which were associated to the up-regulation of CDKN1A, BAX, caspase 9 and E-cadherin mRNA under combined treatment compared to single DOCE treatment. CAT and ProB2 can enhance the efficacy of DOCE therapy on PC and BC cells by the sensitizing mechanism.

SATB1 protein is associated with the epithelial‑mesenchymal transition process in non‑small cell lung cancers

Lung cancer is one of the most frequently diagnosed neoplasms and the leading cause of cancer‑related mortality worldwide. Its predominant subtype is non‑small cell lung cancer (NSCLC), which accounts for over 80% of the cases. Surprisingly, the majority of lung cancer‑related deaths are caused not by a primary tumour itself, but by its metastasis to distant organs. Therefore, it becomes especially important to identify the factors involved in lung cancer metastatic spread. Special AT‑rich binding protein 1 (SATB1) is a nuclear matrix protein that mediates chromatin looping and plays the role of global transcriptional regulator. During the past decade, it has received much attention as a factor promoting tumour invasion. In breast, colorectal and prostate cancers, SATB1 has been shown to influence the epithelial‑mesenchymal transition (EMT) process, which is thought to be crucial for cancer metastasis. The aim of this study was to analyse the possible correlations between the expression of SATB1 and major EMT‑associated proteins in NSCLC clinical samples. Additionally, the impact of EMT induction in NSCLC cell lines on SATB1 mRNA expression was also investigated. Immunohistochemistry was used to assess the expression of SATB1, SNAIL, SLUG, Twist1, E‑cadherin, and N‑cadherin in 242 lung cancer clinical samples. EMT was induced by TGF‑β1 treatment in the A549 and NCI‑H1703 lung cancer cell lines. Changes in gene expression profiles were analyzed using real‑time PCR and Droplet Digital PCR. SATB1 expression was positively correlated with the expression of SNAIL (R=0.129; P=0.045), SLUG (R=0.449; P<0.0001), and Twist1 (R=0.264; P<0.0001). Moreover, SATB1 expression significantly increased after in vitro EMT induction in A549 and NCI‑H1703 cell lines. The results obtained may point to the role of SATB1 as one of the regulators of EMT in NSCLC.

Tackling tumor microenvironment through epigenetic tools to improve cancer immunotherapy

BACKGROUND

Epigenetic alterations are known contributors to cancer development and aggressiveness. Additional to alterations in cancer cells, aberrant epigenetic marks are present in cells of the tumor microenvironment, including lymphocytes and tumor-associated macrophages, which are often overlooked but known to be a contributing factor to a favorable environment for tumor growth. Therefore, the main aim of this review is to give an overview of the epigenetic alterations affecting immune cells in the tumor microenvironment to provoke an immunosuppressive function and contribute to cancer development. Moreover, immunotherapy is briefly discussed in the context of epigenetics, describing both its combination with epigenetic drugs and the need for epigenetic biomarkers to predict response to immune checkpoint blockage.

MAIN BODY

Combining both topics, epigenetic machinery plays a central role in generating an immunosuppressive environment for cancer growth, which creates a barrier for immunotherapy to be successful. Furthermore, epigenetic-directed compounds may not only affect cancer cells but also immune cells in the tumor microenvironment, which could be beneficial for the clinical response to immunotherapy.

CONCLUSION

Thus, modulating epigenetics in combination with immunotherapy might be a promising therapeutic option to improve the success of this therapy. Further studies are necessary to (1) understand in depth the impact of the epigenetic machinery in the tumor microenvironment; (2) how the epigenetic machinery can be modulated according to tumor type to increase response to immunotherapy and (3) find reliable biomarkers for a better selection of patients eligible to immunotherapy.

Combination of oncolytic adenovirus targeting SATB1 and docetaxel for the treatment of castration-resistant prostate cancer

Background: Oncolytic viral therapy is a new strategy for tumor eradication which combines the advantages of viral therapy and gene therapy. Silencing SATB1 exhibits strong inhibitory effect on the growth of prostate cancer. Docetaxel (DTX) is the gold standard for chemotherapy of prostate cancer, but its side effects decrease the life quality of patients. Therefore, it is urgent to develop combination therapy to increase its anti-tumor effect.

Methods: Oncolytic adenovirus targeting SATB1 was constructed and named ZD55-SATB1. Human prostatic cancer cells DU145 and PC-3 and human prostatic stromal cells WPMY-1 were treated with ZD55-SATB1 or/and DTX. In vitro cell proliferation, migration, invasion, apoptosis were detected. In addition, PC-3 cells were injected subcutaneously into nude mice, which were treated with ZD55-SATB1 or/and DTX. Tumor growth was monitored in vivo.

Results: ZD55-SATB1 combined with DTX inhibited proliferation, migration and invasion of DU145 and PC-3 cells, while promoted apoptosis of DU145 and PC-3 cells more efficiently than monotherapy. ZD55-SATB1 had no cytotoxicity on WPMY-1 cells. In animal models, the combined treatment of ZD55-SATB1+DTX and endocrine therapy effectively inhibited the growth of xenograft tumor, accompanied by increased expression of caspase-3 and caspase-8, and decrease expression of Bcl-2 and angiogenesis marker CD31 compared to other treatment groups.

Conclusion: The combination of oncolytic adenovirus ZD55-SATB1 and chemotherapy provides a novel approach to effective therapy of prostate cancer.

3,4-Dihydropyrimidin-2(1H)-ones as Antagonists of the Human A2B Adenosine Receptor: Optimization, Structure-Activity Relationship Studies, and Enantiospecific Recognition

We present and thoroughly characterize a large collection of 3,4-dihydropyrimidin-2(1H)-ones as A_2BAR antagonists, an emerging strategy in cancer (immuno) therapy. Most compounds selectively bind A_2BAR, with a number of potent and selective antagonists further confirmed by functional cyclic adenosine monophosphate experiments. The series was analyzed with one of the most exhaustive free energy perturbation studies on a GPCR, obtaining an accurate model of the structure-activity relationship of this chemotype. The stereospecific binding modeled for this scaffold was confirmed by resolving the two most potent ligands [(±)-47, and (±)-38 K_i = 10.20 and 23.6 nM, respectively] into their two enantiomers, isolating the affinity on the corresponding (S)-eutomers (K_i = 6.30 and 11.10 nM, respectively). The assessment of the effect in representative cytochromes (CYP3A4 and CYP2D6) demonstrated insignificant inhibitory activity, while in vitro experiments in three prostate cancer cells demonstrated that this pair of compounds exhibits a pronounced antimetastatic effect.

Assessment of the Utility of Gene Positioning Biomarkers in the Stratification of Prostate Cancers

There is a pressing need for additional clinical biomarkers to predict the aggressiveness of individual cancers. Here, we examine the potential usefulness of spatial genome organization as a prognostic tool for prostate cancer. Using fluorescence in situ hybridization on formalin-fixed, paraffin embedded human prostate tissue specimens, we compared the nuclear positions of four genes between clinically relevant subgroups of prostate tissues. We find that directional repositioning of SP100 and TGFB3 gene loci stratifies prostate cancers of differing Gleason scores. A more peripheral position of SP100 and TGFB3 in the nucleus, compared to benign tissues, is associated with low Gleason score cancers, whereas more internal positioning correlates with higher Gleason scores. Conversely, LMNA is more internally positioned in many non-metastatic prostate cancers, while its position is indistinguishable from benign tissue in metastatic cancer. The false positive rates were relatively low, whereas, the false negative rates of single or combinations of genes were high, limiting the clinical utility of this assay in its current form. Nevertheless, our findings of subtype-specific gene positioning patterns in prostate cancer provides proof-of-concept for the potential usefulness of spatial gene positioning for prognostic applications, and encourage further exploration of spatial gene positioning patterns to identify novel clinically relevant molecular biomarkers, which may aid treatment decisions for cancer patients.

Glucosinolate-Degradation Products as Co-Adjuvant Therapy on Prostate Cancer in Vitro

Glucosinolate-degradation products (GS-degradation products) are believed to be responsible for the anticancer effects of cruciferous vegetables. Furthermore, they could improve the efficacy and reduce side-effects of chemotherapy. The aim of the present study was to determine the cytotoxic effects of GS-degradation products on androgen-insensitive human prostate cancer (AIPC) PC-3 and DU 145 cells and investigate their ability to sensitize such cells to chemotherapeutic drug Docetaxel (DOCE). Cells were cultured under growing concentrations of allyl-isothiocyanate (AITC), sulforaphane (SFN), 4-pentenyl-isothiocyanate (4PI), iberin (IB), indole-3-carbinol (I3C), or phenethyl-isothiocyanate (PEITC) in absence or presence of DOCE. The anti-tumor effects of these compounds were analyzed using the trypan blue exclusion, apoptosis, invasion and RT-qPCR assays and confocal microscopy. We observed that AITC, SFN, IB, and/or PEITC induced a dose- and time-dependent cytotoxic effect on PC-3 and DU 145 cells, which was mediated, at least, by apoptosis and cell cycle arrest. Likewise, we showed that these GS-degradation products sensitized both cell lines to DOCE by synergic mechanisms. Taken together, our results indicate that GS-degradation products can be promising compounds as co-adjuvant therapy in prostate cancer.

The Role of SATB1 in Tumour Progression and Metastasis

Carcinogenesis is a long-drawn, multistep process, in which metastatic spread is an unequivocal hallmark of a poor prognosis. The progression and dissemination of epithelial cancers is commonly thought to rely on the epidermal-mesenchymal transition (EMT) process. During EMT, epithelial cells lose their junctions and apical-basal polarity, and they acquire a mesenchymal phenotype with its migratory and invasive capabilities. One of the proteins involved in cancer progression and EMT may be SATB1 (Special AT-Rich Binding Protein 1)-a chromatin organiser and a global transcriptional regulator. SATB1 organizes chromatin into spatial loops, providing a "docking site" necessary for the binding of further transcription factors and chromatin modifying enzymes. SATB1 has the ability to regulate whole sets of genes, even those located on distant chromosomes. SATB1 was found to be overexpressed in numerous malignancies, including lymphomas, breast, colorectal, prostate, liver, bladder and ovarian cancers. In the solid tumours, an elevated SATB1 level was observed to be associated with an aggressive phenotype, presence of lymph node, distant metastases, and a poor prognosis. In this review, we briefly describe the prognostic significance of SATB1 expression in most common human cancers, and analyse its impact on EMT and metastasis.

HOXC6 promotes migration, invasion and proliferation of esophageal squamous cell carcinoma cells via modulating expression of genes involved in malignant phenotypes

Background

HOXC6 is a member of the HOX gene family. The elevated expression of this gene occurs in prostate and breast cancers. However, the role of HOXC6 in esophageal squamous cell carcinoma (ESCC) remains largely uninvestigated.

Methods

The expression of HOXC6 was examined by immunohistochemistry, quantitative real-time PCR and immunoblotting assays. The lentivirus-mediated expression of HOXC6 was verified at mRNA and protein levels. Wound healing and Matrigel assays were performed to assess the effect of HOXC6 on the migration and invasion of cancer cells. The growth curving, CCK8, and colony formation assays were utilized to access the proliferation capacities. RNA-seq was performed to evaluate the downstream targets of HOXC6. Bioinformatic tool was used to analyze the gene expression.

Results

HOXC6 was highly expressed in ESCC tissues. HOXC6 overexpression promoted the migration, invasion, and proliferation of both Eca109 and TE10 cells. There were 2,155 up-regulated and 759 down-regulated genes in Eca109-HOXC6 cells and 95 up-regulated and 47 down-regulated genes in TE10-HOXC6 cells compared with the results of control. Interestingly, there were only 20 common genes, including 17 up-regulated and three down-regulated genes with similar changes upon HOXC6 transfection in both cell lines. HOXC6 activated several crucial genes implicated in the malignant phenotype of cancer cells.

Discussion

HOXC6 is highly expressed in ESCC and promotes malignant phenotype of ESCC cells. HOXC6 can be used as a new therapeutic target of ESCC.

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.

Expression of p16 and SATB1 in Invasive Ductal Breast Cancer - A Preliminary Study

BACKGROUND/AIM

An impaired cell-cycle control and genetic material organization are crucial elements of carcinogenesis. p16 is a tumor suppressor protein which decelerates promotion of the cells from G₁ to S phase, whereas special AT-rich sequence-binding protein 1 (SATB1) is a nuclear matrix protein that binds to specific regions of the DNA and ensures its proper organization and function. Increased levels of both markers are observed in various types of cancers. The aim of this study was to investigate the expression of p16 and SATB1 proteins in regard to expression of the Ki-67 antigen and available clinicopathological data (i.a. receptor status, staging and grading).

MATERIALS AND METHODS

The study was performed on 130 samples of archived invasive ductal breast cancers. Immunohistochemical reactions were performed on freshly prepared tissue microarrays and subsequently scanned by a histologic scanner. Reactions were evaluated separately in the cytoplasm (p16c, SATB1c) and nucleus (p16n, SATB1n, Ki-67) with use of a quantification software under researcher supervision.

RESULTS

Expression was observed for Ki-67 in 100%, p16c in 90%, p16n in 89.2%, SATB1c in 98.5% and SATB1n in 87.7% of cancer cases. Statistical analysis showed strong positive correlations: p16c vs. p16n and SATB1c vs. SATB1n (p<0.001 for both) and weak positive correlations: p16c vs. SATB1c and p16c vs. SATB1n (p=0.008, p=0.027; respectively). Expression of p16n was stronger in G₁ vs. G₂ (p=0.034) while Ki-67 expression was stronger in cases with negative progesterone receptor status (p=0.011). All other analyzed associations were statistically insignificant.

CONCLUSION

A weak association between immunohistochemical expression of p16 and SATB1 indicated limited possibility of their independent usage. Further studies concerning determination of a wider panel of proteins controlling cell cycle should be considered.

Expression of p16 and SATB1 in Invasive Ductal Breast Cancer - A Preliminary Study

BACKGROUND/AIM

An impaired cell-cycle control and genetic material organization are crucial elements of carcinogenesis. p16 is a tumor suppressor protein which decelerates promotion of the cells from G₁ to S phase, whereas special AT-rich sequence-binding protein 1 (SATB1) is a nuclear matrix protein that binds to specific regions of the DNA and ensures its proper organization and function. Increased levels of both markers are observed in various types of cancers. The aim of this study was to investigate the expression of p16 and SATB1 proteins in regard to expression of the Ki-67 antigen and available clinicopathological data (i.a. receptor status, staging and grading).

MATERIALS AND METHODS

The study was performed on 130 samples of archived invasive ductal breast cancers. Immunohistochemical reactions were performed on freshly prepared tissue microarrays and subsequently scanned by a histologic scanner. Reactions were evaluated separately in the cytoplasm (p16c, SATB1c) and nucleus (p16n, SATB1n, Ki-67) with use of a quantification software under researcher supervision.

RESULTS

Expression was observed for Ki-67 in 100%, p16c in 90%, p16n in 89.2%, SATB1c in 98.5% and SATB1n in 87.7% of cancer cases. Statistical analysis showed strong positive correlations: p16c vs. p16n and SATB1c vs. SATB1n (p<0.001 for both) and weak positive correlations: p16c vs. SATB1c and p16c vs. SATB1n (p=0.008, p=0.027; respectively). Expression of p16n was stronger in G₁ vs. G₂ (p=0.034) while Ki-67 expression was stronger in cases with negative progesterone receptor status (p=0.011). All other analyzed associations were statistically insignificant.

CONCLUSION

A weak association between immunohistochemical expression of p16 and SATB1 indicated limited possibility of their independent usage. Further studies concerning determination of a wider panel of proteins controlling cell cycle should be considered.

Inhibition of prostate cancer DU145 cell growth with small interfering RNA targeting the SATB1 gene

Prostate cancer is a common visceral cancer of men worldwide. It is important to develop a more effective treatment for prostate cancer to overcome the treatment resistance that occurs with recurrence. RNA interference has been demonstrated to be a powerful tool for gene knockdown and has potential as a cancer treatment. It has been previously demonstrated that staining of special AT-rich sequence-binding protein 1 (SATB1) was stronger in prostatic carcinoma with metastasis compared with prostatic carcinoma without metastasis. In the present study, SATB1 small interfering (si)RNA was transfected into prostate cancer DU145 cells and normal human lung fibroblast cells, and cell proliferation was investigated using a Cell Counting kit-8. Three siRNA were transfected into cells using siPORT Lipid Transfection agent, and blank control and negative control groups were established. The cells were harvested and SATB1 mRNA and protein expression was determined by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. DU145 cell adhesion, migration and invasion capabilities were determined using cell adhesion, Transwell and Transwell with Matrigel assays, respectively. Silencing SATB1 significantly inhibited DU145 cell growth, adhesion, migration and invasive capability in vitro, indicating that a SATB1-targeting siRNA was successfully engineered. The results of the present study suggest that SATB1 siRNA may be a potential agent for treating human prostate cancer.

Gene-expression analysis of gleason grade 3 tumor glands embedded in low- and high-risk prostate cancer

The Gleason score (GS) of prostate cancer on diagnostic biopsies is an important parameter for therapeutic decision-making. Biopsy GS under-estimates the actual GS at radical prostatectomy in a significant number of patients due to sampling artifact. The aim of this study was to identify markers that are differentially expressed in Gleason grade 3 (GG3) tumor glands embedded in GS 4 + 3 = 7 and GS 3 + 3 = 6 prostate cancer using laser capture microdissection and RNA sequencing.

GG3 tumor glands embedded in nine GS 3 + 3 = 6 and nine GS 4 + 3 = 7 prostate cancers were isolated by laser capture microdissection of frozen radical prostatectomy specimens. After RNA amplification and RNA sequencing, differentially expressed genes in both GG3 components were identified by a 2log fold change > 1.0 and p-value < 0.05. We applied immunohistochemistry on a tissue micro-array representing 481 radical prostatectomy samples for further validation on protein level.

A total of 501 genes were up-regulated and 421 down-regulated in GG3 glands embedded in GS 4 + 3 = 7 as compared to GS 3 + 3 = 6 prostate cancer. We selected HELLS, ZIC2 and ZIC5 genes for further validation. ZIC5 mRNA was up-regulated 17 fold (p = 8.4E–07), ZIC2 8 fold (p = 1.3E–05) and HELLS 2 fold (p = 0.006) in GG3 glands derived from GS 4 + 3 = 7. HELLS expression of ≥ 1% occurred in 10% GS < 7, 17% GS 7 and 43% GS >7 prostate cancer (p < 0.001). Using a cut-off of ≥ 1%, protein expression of ZIC5 was present in 28% GS < 7, 43% GS 7 and 57% GS > 7 cancer (p < 0.001). ZIC2 was neither associated with GS nor outcome in our validation set. HELLS was independently predictive for biochemical-recurrence after radical prostatectomy (HR 2.3; CI 1.5–3.6; p < 0.01).

In conclusion, HELLS and ZIC5 might be promising candidate markers for selection of biopsy GS 6 prostate cancer being at risk for up-grading at prostatectomy.

High expression of special AT-rich sequence binding protein-1 predicts esophageal squamous cell carcinoma relapse and poor prognosis

Previous studies of the roles of special AT-rich sequence binding protein-1 (SATB1) in the development and progression of cancer have suggested that SATB1 promotes cancer cell metastasis. The aim of the present study is to evaluate the role of SATB1 in the progression and prognosis of esophageal squamous cell carcinoma (ESCC). ESCC tissues were collected from 102 patients and SATB1 mRNA expression was measured by reverse transcription-quantitative polymerase chain reaction. The association between expression of SATB1 mRNA with clinicopathological features and prognosis was assessed, and the prognosis of ESCC was evaluated using Kaplan-Meier survival curves. In the 102 ESCC tissues, SATB1 mRNA expression correlated with the clinical tumor node metastasis stage (P<0.05), but not with any other clinicopathological features (including age, gender, tumor differentiation grade, adjuvant radio/chemotherapy, or the consumption of alcohol and use of cigarettes) (P>0.05). The disease-free survival (DFS) and overall survival (OS) of patients with high SATB1 expression was decreased compared with those with low SATB1 expression. The present study indicated that SATB1 mRNA expression was associated with the postoperative recurrent and poor prognosis in ESCC. SATB1 may be a novel marker for predicting the recurrent and worse prognosis of ESCC.

Inhibition of prostate cancer cell growth in vivo with short hairpin RNA targeting SATB1

Despite previous advances, the treatment options for prostate cancer remain limited. For the purposes of gene knockdown, the utility of RNA interference has been demonstrated and is considered to have therapeutic potential. In the present study, a short hairpin RNA (shRNA) was used to assess the effect of special AT-rich sequence binding protein (SATB1) downregulation on the growth and metastatic potential of prostate cancer in xenograft nude mice. A plasmid carrying shRNA targeting SATB1, pSilencer-SATB1-shRNA, was successfully engineered. Using this plasmid, significant downregulation of SATB1 mRNA and protein expression in the DU145 prostate cancer cells was observed. pSilencer-SATB1-shRNA was demonstrated to be markedly efficacious against prostate cancer xenografts in nude mice. These results may lead to a novel method of improving gene therapy efficacy against prostate cancer via regulating the function of SATB1.

SATB1 plays an oncogenic role in esophageal cancer by up-regulation of FN1 and PDGFRB

Esophageal cancer is a highly aggressive malignancy with very poor overall prognosis. Given the strong clinical relevance of SATB1 in esophagus cancer and other cancers suggested by previous studies, the exact function of SATB1 in esophagus cancer development is still unknown. Here we showed that the knockdown of SATB1 in esophageal cancer cell lines diminished the cell proliferation, survival and invasion. Whole genome transcriptome analysis of SATB1 knockdown cells revealed the different gene expression profiles between TE-1 cells and MDA-MB-231 cells. Network analysis and functional experiments further identified FN1 and PDGFRB to be key downstream genes regulated by SATB1 in esophageal cancer cells. Importantly, FN1 and PDGFRB were found to be highly expressed in human esophageal cancer. In summary, we provided the first molecular evidence that SATB1 played an oncogenic role in esophageal cancer by up-regulation of FN1 and PDGFRB.

miR-203 Suppresses Bladder Cancer Cell Growth and Targets Twist1

miR-203 is an epigenetically silenced tumor-suppressive microRNA in tumors. This study was designed to investigate the effects of miR-203 on the proliferation, migration, invasion, and apoptosis of bladder cancer (BCa) cells. The expression levels of miR-203 in BCa tissues, normal adjacent tissues, and BCa cell lines were detected. BCa cells were transfected with miR-203 mimic and inhibitor to investigate the effect of miR-203 on cell functions and the epithelial–mesenchymal transition (EMT). Cotransfection with miR-203 inhibitor and shRNA of the predicted target gene Twist1 (si-Twist1) was performed to investigate the target relationship of miR-203 and Twist1. The effects of knockdown of Twist1 on cell functions were also investigated. The expression of miR-203 was significantly reduced in BCa tissues and cells, in comparison with the control. miR-203 mimic significantly reduced cell viability, invasion, migration, and EMT, and enhanced cell apoptosis. On the contrary, miR-203 inhibitor showed the opposite results. However, the administration of si-Twist1 cancelled the effect of miR-203 inhibitor on cell proliferation, apoptosis, invasion, and migration. These demonstrated that miR-203 may function as a tumor-suppressive microRNA in BCa by negatively targeting Twist1. Both Twist1 and miR-203 might be explored as potential targets for studying the mechanism related to BCa pathogenesis and therapy.

Special AT-rich sequence binding protein 1 promotes tumor growth and metastasis of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma is one of the most aggressive malignancies worldwide. Special AT-rich sequence binding protein 1 is a nuclear matrix attachment region binding protein which participates in higher order chromatin organization and tissue-specific gene expression. However, the role of special AT-rich sequence binding protein 1 in esophageal squamous cell carcinoma remains unknown. In this study, western blot and quantitative real-time polymerase chain reaction analysis were performed to identify differentially expressed special AT-rich sequence binding protein 1 in a series of esophageal squamous cell carcinoma tissue samples. The effects of special AT-rich sequence binding protein 1 silencing by two short-hairpin RNAs on cell proliferation, migration, and invasion were assessed by the CCK-8 assay and transwell assays in esophageal squamous cell carcinoma in vitro. Special AT-rich sequence binding protein 1 was significantly upregulated in esophageal squamous cell carcinoma tissue samples and cell lines. Silencing of special AT-rich sequence binding protein 1 inhibited the proliferation of KYSE450 and EC9706 cells which have a relatively high level of special AT-rich sequence binding protein 1, and the ability of migration and invasion of KYSE450 and EC9706 cells was distinctly suppressed. Special AT-rich sequence binding protein 1 could be a potential target for the treatment of esophageal squamous cell carcinoma and inhibition of special AT-rich sequence binding protein 1 may provide a new strategy for the prevention of esophageal squamous cell carcinoma invasion and metastasis.

SATB1 promotes tumor metastasis and invasiveness in oral squamous cell carcinoma

OBJECTIVE

Our aim is to evaluate the expression of SATB1 in human oral squamous cell carcinomas (OSCC) and its role in the invasiveness and metastasis of OSCC.

SUBJECTS AND METHODS

A human OSCC tissue microarray was used to evaluate the expression pattern of SATB1. SATB1 mRNA knockdown was performed in human OSCC cell lines SCC25 and Cal27 to assess the function of SATB1 in the invasiveness and metastasis of OSCC.

RESULTS

SATB1 is highly expressed in human OSCC determined by immunohistochemistry, and its nuclear/cytoplasmic ratio of histoscore is significantly correlated with patients' prognosis. Reduced cell motility, invasiveness, expression of epithelial to mesenchymal transition (EMT) markers (N-cadherin and β-catenin), and elevated expression of epithelial markers were observed in SATB1-knockdown cells in in vitro studies. Depletion of SATB1 also restored a cobblestone-like morphology in TGF-β1-treated cells.

CONCLUSIONS

These findings suggest SATB1 may play an important role in OSCC invasiveness and metastasis.

SATB1 and SATB2 play opposing roles in c-Myc expression and progression of colorectal cancer

Special AT-rich sequence-binding protein 1 and 2 (SATB1/2) are nuclear matrix-associated proteins involved in chromatin remodeling and regulation of gene expression. SATB2 acts as a tumor suppressor in laryngeal squamous cell carcinoma and colon cancer, whereas SATB1 promotes the progression of numerous types of cancers. In this study, we examined the effects of SATB1 and SATB2 on the malignant characteristics of colorectal cancer cells. SATB1 and SATB2 expression were negatively correlated in colorectal cancer specimens. SATB1 expression was increased, whereas SATB2 expression was reduced, in colorectal cancer tissues compared to control tissues. Exogenous expression of SATB2 in colorectal cancer cells suppressed cell proliferation, colony formation and tumor proliferation in mice. c-Myc was reduced by SATB2 expression, and exogenous expression of c-Myc in SATB2-expressing cells restored proliferation, colony formation and in vivo tumor growth of colorectal cancer cells. We also showed that c-Myc reduction by SATB2 was mediated by the inactivation of ERK5. In contrast, SATB1 promoted c-Myc expression. The expression of SATB1 in colorectal cancer tissues was positively correlated with c-Myc expression, and SATB1 knockdown reduced c-Myc expression in colorectal cancer cells. Finally, we showed that SATB1 knockdown in colorectal cancer cells suppressed cell proliferation, colony formation and cell invasion. Our results reveal interesting features of how the structural homologs SATB1 and SATB2 exert opposing functions in colorectal tumorigenesis.

Special AT-rich DNA-binding protein-1 expression is associated with liver cancer metastasis

To aim of the present study was to investigate the association between special AT-rich DNA-binding protein-1 (SATB1) expression and liver cancer metastasis. SATB1 mRNA and protein expression in hepatocellular carcinoma tissues was analyzed by immunohistochemistry, and in two hepatocellular cancer cell lines, MHCC-97H (high metastatic potential) and HepG2 (low metastatic potential), by reverse transcription-polymerase chain reaction and western blot analysis. Transwell migration and wound-healing assays were also performed to investigate the metastasis of liver cancer following upregulation or silencing of SATB1 expression. The results revealed that SATB1 expression was significantly higher in hepatocellular carcinoma tissues compared with carcinoma-adjacent tissues. Furthermore, SATB1 expression was correlated with tumor size, differentiation degree, hemorrhage and/or necrosis, invasion and/or metastases and TNM stage. Both the mRNA and protein expression of SATB1 was higher in MHCC-97H cells than HepG2 cells. In addition, the migration capability of MHCC-97H cells was decreased after SATB1 silencing, whereas the migration capability of HepG2 cells was increased after SATB1 upregulation. SATB1 expression was demonstrated to be positively correlated with liver cancer metastasis. These results indicate that liver cancer metastasis is regulated by SATB1 expression. Thus, immunohistochemical SATB1 expression may present an independent risk factor for the metastasis of liver cancer.

Pilot study special AT-rich sequence-binding protein 1 investigating as a potential biomarker for esophageal squamous cell carcinoma

In the present study, we aimed to evaluate the expression of special AT-rich sequence-binding protein 1 (SATB1) in esophageal squamous cell carcinoma (ESCC) and assess the correlation between its expression and the clinicopathological features and prognosis of the disease. SATB1 expression in ESCC tissue was determined by using immunohistochemical analysis, quantitative real-time polymerase chain reaction, and western blot analysis. The relationship between SATB1 expression and clinicopathological features was examined by using the chi-squared test, and the survival rate was calculated by using the Kaplan-Meier survival curve. The correlation between the indicators and patient survival was estimated by using a Cox regression analysis. High SATB1 expression in was detected in 48.3% and 7.8% of ESCC and normal esophagus tissues (P < 0.05), respectively. SATB1 expression did not significantly correlate with clinicopathological features. The Kaplan-Meier curve indicated that patients with high SATB1 expression had significantly shorter survival than those with low SATB1 expression. In a multivariate Cox regression model, high SATB1 expression was identified as an independent prognostic factor for patients with ESCC. In conclusion, these results suggest that high SATB1 expression is predictive of poor prognosis in ESCC and may be a promising new candidate for targeted therapies for ESCC.

Baicalein suppresses metastasis of breast cancer cells by inhibiting EMT via downregulation of SATB1 and Wnt/β-catenin pathway

BACKGROUND

The flavonoid baicalein, a historically used Chinese herbal medicine, shows a wide range of biological and pharmaceutical effects, among which its potent antitumor activity has raised great interest in recent years. However, the molecular mechanism involved in the antimetastatic effect of baicalein remains poorly understood. This study aimed to verify the inhibitory effects of baicalein on metastasis of MDA-MB-231 human breast cancer cells both in vitro and in vivo, as well as to investigate the related mechanisms.

METHODS

MTT assay was used to examine the inhibition of baicalein on proliferation of MDA-MB-231 cells. Wound healing assay and the in vitro invasion assay was carried out to investigate the effects of baicalein on migration and invasion of MDA-MB-231 cells, respectively. In order to explore the effects of baicalein on tumor metastasis in vivo, xenograft nude mouse model of MDA-MB-231 cells was established. Animals were randomly divided into four groups (control, therapy group, and low-dose and high-dose prevention group, n=6), and treated with baicalein as designed. Following sacrifice, their lungs and livers were collected to examine the presence of metastases. qRT-PCR and Western blot were performed to study the effects of baicalein on expression of SATB1, EMT-related molecules, and Wnt/β-catenin signaling components of MDA-MB-231 cells as well as the metastatic tissue. Effects of baicalein on the expression of target proteins in vivo were also analyzed by immunohistochemistry.

RESULTS

Our results indicated that baicalein suppressed proliferation, migration, and invasion of MDA-MB-231 cells in a time- and dose-dependent manner. Based on assays carried out in xenograft nude mouse model, we found that baicalein inhibited tumor metastasis in vivo. Furthermore, baicalein significantly decreased the expression of SATB1 in MDA-MB-231 cells. It suppressed the expression of vimentin and SNAIL while enhancing the expression of E-cadherin. Baicalein also downregulated the expression of Wnt1 and β-catenin proteins and transcription level of Wnt/β-catenin-targeted genes.

CONCLUSION

Our results demonstrate that baicalein has the potential to suppress breast cancer metastasis, possibly by inhibition of EMT, which may be attributed to downregulation of both SATB1 and the Wnt/β-catenin pathway. Taken together, baicalein may serve as a promising drug for metastasis treatment of breast cancer.

SATB1 promotes prostate cancer metastasis by the regulation of epithelial-mesenchymal transition

Special AT-rich sequence binding protein 1 (SATB1) plays important role in the regulation of chromatin structure and gene expression. Recent studies have indicated oncogenic role of SATB1. However, the function of SATB1 in prostate cancer progression and metastasis remains unclear. In this study SATB1 expression vector or siRNA was employed to modulate the expression level of SATB1 in prostate cancer cells and xenograft tumor in nude mouse model. Immunohistochemical analysis was performed on clinical prostate cancer samples. Silencing SATB1 inhibited the growth of DU-145 cells subcutaneous tumor in nude mice, while SATB1 overexpression promoted the growth of LNCaP cells subcutaneous tumor in nude mice. Immunohistochemical and Western blot analysis of the xenografts showed that silencing SATB1 led to decreased expression of vimentin and MMP2 and increased expression of E-cadherin, while SATB1 overexpression led to increased expression of vimentin and MMP2 and decreased expression of E-cadherin. Furthermore, SATB1, vimentin and MMP2 expression was increased significantly while E-cadherin expression was reduced significantly in clinical samples of prostate carcinoma with metastasis compared to prostate carcinoma without metastasis and benign prostate hyperplasia. Taken together, these findings suggest that the modulation of epithelial-mesenchymal transition by SATB1 may contribute to prostate cancer metastasis.

SATB1 expression is correlated with β-catenin associated epithelial-mesenchymal transition in colorectal cancer

SATB1, a global gene regulator, has been implicated in the growth and metastasis of multiple cancers, including colorectal cancer. While the understanding about the role of SATB1 in CRC remains limited. The aim of our study is to investigate the expression of SATB1 in CRC, and the relationship between SATB1 expression pattern and clinicopathological variables. A further aim is to analyze the correlation between SATB1 expression and epithelial-mesenchymal transition in CRC. Immunohistochemical expression of SATB1, β-catenin, E-cadherin, CK20, Vimentin, SMA, and desmin were assessed in a cohort of 200 patients using tissue microarrays. SATB1 was expressed in 133 (66.5%) CRC primary lesions, 14 (28%) adjacent colorectal mucosa specimens, and 60 (75%) corresponding lymph node metastases. The expression level of SATB1 was significantly higher in lymph node metastases than in CRC primary lesions and normal mucosa (P = 0.000). High expression of SATB1 in CRC was strongly correlated with poor differentiation of tumor tissues (P = 0.000). High expression of SATB1 was significantly correlated with aberrant expression of β-catenin (P = 0.0005), low expression of E-cadherin (P = 0.000) and CK20 (P = 0.000) and with high expression of Vimentin (P = 0.001). No SMA or desmin protein was expressed in the CRC cells. Our results suggested that high expression of SATB1 is significantly correlated with poor differentiation of CRC. SATB1 might promote the epithelial-mesenchymal transition by increasing the aberrant expression of β-catenin.

SATB1 is a potential therapeutic target in intrahepatic cholangiocarcinoma

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

SATB1 Mediates Long-Range Chromatin Interactions: A Dual Regulator of Anti-Apoptotic BCL2 and Pro-Apoptotic NOXA Genes

Aberrant expression of special AT-rich binding protein 1 (SATB1), a global genomic organizer, has been associated with various cancers, which raises the question of how higher-order chromatin structure contributes to carcinogenesis. Disruption of apoptosis is one of the hallmarks of cancer. We previously demonstrated that SATB1 mediated specific long-range chromosomal interactions between the mbr enhancer located within 3’-UTR of the BCL2 gene and the promoter to regulate BCL2 expression during early apoptosis. In the present study, we used chromosome conformation capture (3C) assays and molecular analyses to further investigate the function of the SATB1-mediated higher-order chromatin structure in co-regulation of the anti-apoptotic BCL2 gene and the pro-apoptotic NOXA gene located 3.4Mb downstream on Chromosome 18. We demonstrated that the mbr enhancer spatially juxtaposed the promoters of BCL2 and NOXA genes through SATB1-mediated chromatin-loop in Jurkat cells. Decreased SATB1 levels switched the mbr-BCL2 loop to mbr-NOXA loop, and thus changed expression of these two genes. The SATB1-mediated dynamic switch of the chromatin loop structures was essential for the cooperative expression of the BCL2 and NOXA genes in apoptosis. Notably, the role of SATB1 was specific, since inhibition of SATB1 degradation by caspase-6 inhibitor or caspase-6-resistant SATB1 mutant reversed expression of BCL-2 and NOXA in response to apoptotic stimulation. This study reveals the critical role of SATB1-organized higher-order chromatin structure in regulating the dynamic equilibrium of apoptosis-controlling genes with antagonistic functions and suggests that aberrant SATB1 expression might contribute to cancer development by disrupting the co-regulated genes in apoptosis pathways.

Oncolytic virus carrying shRNA targeting SATB1 inhibits prostate cancer growth and metastasis

Recent studies suggest that SATB1 is a promising therapeutic target for prostate cancer. To develop novel SATB1-based therapeutic agents for prostate cancer, in this study, we aimed to construct ZD55-SATB1, an oncolytic adenovirus ZD55 carrying shRNA targeting SATB1, and investigate its effects on the inhibition of prostate cancer growth and metastasis. ZD55-SATB1 was constructed and used to infect human prostate cancer cell lines DU145 and LNCaP. The inhibitory effect of ZD55-SATB1 on SATB1 expression was evaluated by reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. The cytotoxicity of ZD55-SATB1 was detected by MTT assay. Cell invasion was detected by Matrigel invasion assay. The in vivo antitumor activities of ZD55-SATB1 were evaluated in xenograft mouse model. We found that ZD55-SATB1 selectively replicated and significantly reduced SATB1 expression in DU145 and LNCaP cells. ZD55-SATB1 effectively inhibited the viability and invasion of DU145 and LNCaP cells in vitro and inhibited prostate cancer growth and metastasis in xenograft nude mice. In conclusion, replicative oncolytic adenovirus armed with SATB1 shRNA exhibits effective antitumor effect in human prostate cancer. Our study provides the basis for the development of ZD55-SATB1 for the treatment of prostate cancer.

Analysis of MicroRNA Expression Profile Identifies Novel Biomarkers for Non-small Cell Lung Cancer

Background

Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer mortality. MicroRNAs (miRNAs), small noncoding RNAs, regulate the expression of genes that play roles in human cancer via posttranscriptional inhibition.

Methods

To identify the potential miRNA biomarkers in NSCLC, we downloaded the miRNA expression profile (ID: GSE29248) of NSCLC from the Gene Expression Omnibus (GEO) database and analyzed the differentially expressed miRNAs in NSCLC tissue compared with normal control tissue. Then the targets of these differentially expressed miRNAs were screened and used in network construction and functional enrichment analysis.

Results

We identified a total of 17 miRNAs that showed a significantly differential expression in NSCLC tissue. We found that miR-34b and miR-520h might play important roles in the regulation of NSCLC, miR-22 might be a novel biomarker as an oncogene, and miR-448 might promote, while miR-654-3p prevents, NSCLC progression.

Conclusions

Our study may provide the groundwork for further clinical molecular target therapy experiments in NSCLC.

miR-23a suppresses proliferation of osteosarcoma cells by targeting SATB1

Accumulating evidence has shown that microRNAs are involved in multiple processes in cancer development and progression. Recent studies have shown that miR-23a functions as an oncogene in various human cancer types, but its role in osteosarcoma remains poorly understood. Here, we demonstrated that miR-23a is frequently downregulated in osteosarcoma specimens and cell lines compared with adjacent noncancerous tissues and cell line. Bioinformatics analysis further revealed SATB1 as a potential target of miR-23a. Data from luciferase reporter assays showed that miR-23a directly binds to the 3'UTR of SATB1 messenger RNA (mRNA). Furthermore, we found that expression patterns of miR-23a were inversely correlated with those of SATB1 in osteosarcoma tissues and cell lines, and overexpression of miR-23a suppressed SATB1 expression at both transcriptional and translational levels in osteosarcoma cell lines. In functional assays, miR-23a inhibited osteosarcoma cell proliferation, which could be reversed by overexpression of SATB1. Furthermore, knockdown of SATB1 reduced osteosarcoma cell proliferation, which resembled the inhibitory effects of miR-23a overexpression. Taken together, our data provide compelling evidence that miR-23a functions as a tumor suppressor in osteosarcoma, and its inhibitory effect on tumor are mediated chiefly through downregulation of SATB1.

Nicotinamide induces apoptosis of F9 mouse teratocarcinoma stem cells by downregulation of SATB1 expression

The aim of this study was to decide whether nicotinamide (NA) could induce apoptosis of F9 mouse teratocarcinoma stem cells (MF9) by downregulation of special AT-rich sequence binding protein 1 (SATB1) expression. We used different concentrations of NA (0, 1.5, 2, and 2.5 mmol/L) to treat MF9 cells and analyze SATB1 expression by RT-qPCR and Western blotting; in addition, the cell proliferation was detected in a microplate reader with Cell Counting Kit-8 (CCK-8), and the cell cycle and apoptosis were analyzed using flow cytometry. We found that the expression of SATB1 was decreased significantly in NA-treated groups than in the control group, and its expression level was inversely related to the NA concentration. In addition, CCK-8 analysis showed that NA significantly inhibited the proliferation of MF9 cells, and flow cytometry showed that NA blocked MF9 cells to G1 phase and significantly promoted apoptosis in any treated groups. To confirm the results, we constructed small interference RNA (siRNA) targeting at mouse SATB1 and transferred into MF9 cells. The results indicated that the expression of SATB1 in both mRNA and protein levels was significantly decreased after cells transferred with siRNA sequence for 48 h, the proliferation of MF9 cells was significantly inhibited, and most of MF9 cells were blocked at G1 phase, and the apoptosis rate was increased obviously. The results showed that NA could inhibit the proliferation and induce apoptosis of MF9 cells. These findings might be used as an efficient candidate for teratocarcinoma therapy.

SATB1 Promotes Pancreatic Cancer Growth and Invasion Depending on MYC Activation

BACKGROUND

SATB1 plays an important role in human malignant progression, inducing cancer cell proliferation and metastasis by regulating downstream gene expressions. However, little is known about the underlying mechanisms in which SATB1 promotes pancreatic cancer tumorigenesis.

AIMS

To investigate SATB1 expression levels and its biological functions in promoting pancreatic cancer growth and invasion.

METHODS

SATB1 expression levels were detected in seven human pancreatic cancer cell lines and 16 pairs of normal pancreatic/pancreatic cancer tissues using RT-PCR and western blot. SW1990 or Capan-1 cells stably knockdown (shRNA) or transiently knockdown (siRNA) SATB1 cells, and PANC-1 stably overexpressing SATB1 cells were investigated with MTT, EdU assay, flow cytometry, and transwell invasion assay for cell proliferation and invasion activity. The binding of SATB1 to MYC promoter region was examined using reporter assay. Expression of SATB1 in 68 pancreatic cancer samples was studied by immunohistochemical staining and scoring.

RESULTS

SATB1 was overexpressed in pancreatic cancer tissues samples, showing strong correlation with pancreatic cancer invasion depth and tumor staging. SATB1 induced MYC mRNA and protein expression; promoted pancreatic cancer cell growth; increased cell population in S phase; and enhanced pancreatic cancer cell invasion in vitro. On the other hand, SATB1 knockdown showed opposite effects. Furthermore, MYC blocking in SATB1-overexpressing cells attenuated the promotion of pancreatic cancer cell growth and invasion. Our data also indicated that SATB1 bound to specific promoter region of MYC.

CONCLUSIONS

SATB1 is overexpressed in pancreatic cancer, promoting cancer cell proliferation and invasion through the activation of MYC.

Overexpression of Special AT-Rich Sequence-Binding Protein 1 in Endometrial Cancer: A Clinicopathologic Study

Objective

Special AT-rich sequence-binding protein 1 (SATB1), as a genome organizer, serves important functions in tumor progression and metastasis. The SATB1 is overexpressed in various malignant tumors. However, the expression and prognostic value of SATB1 in endometrial cancer remain unknown. The aim of this study was to explore the prognostic values of SATB1 expression in endometrial cancer.

Methods/Materials

We investigated the expression of SATB1 in 172 untreated endometrial cancer tissues and 25 normal endometrial tissues through immunohistochemical staining. We also analyzed the association of SATB1 level with clinicopathologic parameters and determined its prognostic significance.

Result

Special AT-rich sequence-binding protein 1 was expressed in 78 (45.3%) of the 172 endometrial cancer samples, but not in the normal endometrial samples. The positive expression of SATB1 was associated with clinicopathologic factors, such as International Federation of Gynecology and Obstetrics stage, histological grade, myometrial invasion depth, lymph node metastasis, vascular/lymphatic invasion, and recurrence. The patients with positive SATB1 expression had worse overall survival and disease-free survival rates than the patients with negative SATB1 expression (P< 0.001 for both). Multivariate Cox analysis indicated that SATB1 was an independent parameter for overall survival (hazards ratio, 2.928; 95% confidence interval, 1.072–7.994;P= 0.036) and disease-free survival (hazards ratio, 2.825; 95% confidence interval, 1.111–7.181;P= 0.029).

Conclusions

Results showed that SATB1 may be involved in tumor development and progression in endometrial cancer, may serve as a promising biomarker for predicting the prognosis of endometrial cancer patients, and thus may act as a novel target for treating endometrial carcinoma.

SATB1 and 2 in colorectal cancer

The special AT-rich sequence-binding proteins 1 and 2 (SATB1/2) are nuclear matrix associated proteins that are transcription factors involved in chromatin remodeling and gene regulation. Expression of the SATB2 gene is tissue-specific, and the only epithelial cells expressing SATB2 are the glandular cells of the lower gastrointestinal tract where its expression is regulated by microRNA-31 (miR-31) and miR-182. SATB2, along with its homolog SATB1, are thought to be involved in various cancers with their roles in this disease being specific to the type of cancer. Colorectal cancer (CRC) provides the largest association of SATB2 with cancer and the roles of SATB2 are better defined and more studied in CRC than in any other cancer type. SATB1 displays a negative association with SATB2 in CRC. The various studies that have investigated the involvement of SATB1 and 2 in CRC have produced consistent findings. Here, we form four major conclusions regarding the role of these proteins in CRC and their potential clinical value: (i) SATB2 is a sensitive marker to distinguish CRC from other cancer types, (ii) Reduced expression of SATB2 in CRC is associated with poor prognosis, (iii) High levels of SATB1 expression facilitate CRC and are associated with poor prognosis and (iv) Overexpression of miR-31 and -182 in CRC leads to more aggressive cancer. This review will describe several of the key investigations that established these conclusions and highlight results that offer opportunities for future research in the treatment and diagnosis of CRC.

Expression of special AT-rich sequence-binding protein 1 is an independent prognostic factor in cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) is a group of slowly progressive, lymphoproliferative disorders characterized by localization of neoplastic T lymphocytes to the skin. The most common type of CTCL is mycosis fungoides which has a mild clinical course with slow and long progression. The rate of progression is generally slow and takes many years but often remains unpredictable. Special AT-rich sequence-binding protein-1 (SATB1) is a global chromatin organizer which controls gene expression by folding and remodeling chromatin, but which also regulates the level of histone methylation and acetylation, important in differentiation and apoptosis. The aim of the present study was to determine if SATB1 may be considered a prognostic and predictive factor of CTCL. The results showed that moderate and high expression of SATB1 correlate with significantly better prognosis of CTCL patients. Moreover, we showed that downregulation of SATB1 in Jurkat cells caused their resistance to activation-induced cell death. In conclusion, SATB1 expression appears to be a strong candidate as a prognostic factor confirming the inner heterogeneous features of CTCLs.

Prognostic and treatment predictive significance of SATB1 and SATB2 expression in pancreatic and periampullary adenocarcinoma

BACKGROUND

Pancreatic cancer and other pancreaticobiliary type periampullary adenocarcinomas have a dismal prognosis even after resection and neoadjuvant chemotherapy. Intestinal type periampullary adenocarcinomas generally have a better prognosis, but little is known on optimal neoadjuvant and adjuvant treatment. New prognostic and treatment predictive biomarkers are needed for improved treatment stratification of patients with both types of periampullary adenocarcinoma. Expression of the Special AT-rich sequence-binding protein 1 (SATB1) has been demonstrated to confer a worse prognosis in several tumour types, whereas its close homologue SATB2 is a proposed diagnostic and favourable prognostic marker for colorectal cancer. The prognostic value of SATB1 and SATB2 expression in periampullary adenocarcinoma has not yet been described.

METHODS

Immunohistochemical expression of SATB1 and SATB2 was analysed in tissue microarrays with primary tumours and a subset of paired lymph node metastases from 175 patients operated with pancreaticoduodenectomy for periampullary adenocarcinoma. Kaplan-Meier and Cox regression analysis were applied to explore the impact of SATB1 and SATB2 expression on recurrence free survival (RFS) and overall survival (OS).

RESULTS

Positive expression of SATB1 was denoted in 16/106 primary pancreatobiliary type tumours and 11/65 metastases, and in 15/63 primary intestinal type tumours and 4/26 metastases, respectively. Expression of SATB1 was an independent predictor of a significantly shorter RFS and OS in pancreatobiliary type, but not in intestinal type adenocarcinomas. Moreover, SATB1 expression predicted an improved response to adjuvant chemotherapy in both tumour types. SATB2-expression was seen in 3/107 pancreatobiliary type primary tumours, and in 8/61 intestinal type primary tumours. The small number of cases with positive SATB2 expression did not allow for any firm conclusions on its prognostic value.

CONCLUSIONS

These findings demonstrate the potential utility of SATB1 as a prognostic and predictive biomarker for chemotherapy response in both intestinal type and pancreatobiliary type periampullary adenocarcinomas, including pancreatic cancer.