Special AT-rich sequence-binding protein 1 promotes cell growth and metastasis in colorectal cancer

AIM: To evaluate the expression of special AT-rich sequence-binding protein 1 (SATB1 ) gene in colorectal cancer and its role in colorectal cancer cell proliferation and invasion.METHODS: Immunohistochemistry was used to detect the protein expression of SATB1 in 30 colorectal cancer (CRC) tissue samples and pair-matched adjacent nontumor samples. Cell growth was investigated after enhancing expression of SATB1. Wound-healing assay and Transwell assay were used to investigate the impact of SATB1 on migratory and invasive abilities of SW480 cells in vitro . Nude mice that received subcutaneous implantation or lateral tail vein were used to study the effects of SATB1 on tumor growth or metastasis in vivo . RESULTS: SATB1 was over-expressed in CRC tissues and CRC cell lines. SATB1 promotes cell proliferation and cell cycle progression in CRC SW480 cells. SATB1 over-expression could promote cell growth in vivo . In addition, SATB1 could significantly raise the ability of cell migration and invasion in vitro and promote the ability of tumor metastasis in vivo . SATB1 could up-regulate matrix metalloproteases 2, 9, cyclin D1 and vimentin, meanwhile SATB1 could down-regulate E-cadherin in CRC. CONCLUSION: SATB1 acts as a potential growth and metastasis promoter in CRC. SATB1 may be useful as a therapeutic target for CRC.

Special AT-rich sequence-binding protein 2 acts as a negative regulator of stemness in colorectal cancer cells

AIM To find the mechanisms by which special AT-rich sequence-binding protein 2(SATB2) influences colorectal cancer(CRC) metastasis.METHODS Cell growth assay, colony-forming assay, cell adhesion assay and cell migration assay were used to evaluate the biological characteristics of CRC cells with gain or loss of SATB2. Sphere formation assay was used to detect the self-renewal ability of CRC cells. The m RNA expression of stem cell markers in CRC cells with upregulated or downregulated SATB2 expression was detected by quantitative real-time polymerase chain reaction. Chromatin immunoprecipitation(Ch IP) was used to verify the binding loci of SATB2 on genomic sequences of stem cell markers. The Cancer Genome Atlas(TCGA) database and our clinical samples wereanalyzed to find the correlation between SATB2 and some key stem cell markers.RESULTS Downregulation of SATB2 led to an aggressive phenotype in SW480 and DLD-1 cells, which was characterized by increased migration and invasion abilities. Overexpression of SATB2 suppressed the migration and invasion abilities in SW480 and SW620 cells. Using sequential sphere formation assay to detect the selfrenewal abilities of CRC cells, we found more secondary sphere formation but not primary sphere formation in SW480 and DLD-1 cells after SATB2 expression was knocked down. Moreover, most markers for stem cells such as CD133, CD44, AXIN2, MEIS2 and NANOG were increased in cells with SATB2 knockdown and decreased in cells with SATB2 overexpression. Ch IP assay showed that SATB2 bound to regulatory elements of CD133, CD44, MEIS2 and AXIN2 genes. Using TCGA database and our clinical samples, we found that SATB2 was correlated with some key stem cell markers including CD44 and CD24 in clinical tissues of CRC patients.CONCLUSION SATB2 can directly bind to the regulatory elements in the genetic loci of several stem cell markers and consequently inhibit the progression of CRC by negatively regulating stemness of CRC cells.

A novel SATB1 binding site in the BCL2 promoter region possesses transcriptional regulatory function

BCL2 is a key regulator of apoptosis.Our previous work has demonstrated that special AT-rich sequence-binding protein 1 （SATB1） is positively correlated with BCL2 expression.In the present study,we report a new SATB1 binding site located between P1 and P2 promoters of the BCL2 gene.The candidate SATB1 binding sequence predicted by bioinformatic analysis was investigated in vitro and in vivo by electrophoretic gel mobility shift assays （EMSA） and chromatin immunoprecipitation （ChIP）.One 25-bp sequence,named SB1,was confirmed to be SATB1 binding site.The regulatory function of SB1 and its relevance to SATB1 were further examed with dual-luciferase reporter assay system in Jurkat cells.We found that SB1 could negatively regulate reporter gene activity.Mutation of SATB1 binding site further repressed the activity.Knockdown of SATB1 also enhanced this negative effect of SB1.Our data indicate that the SB1 sequence possesses negative transcriptional regulatory function and this function can be antagonized by SATB1.

SATB1在胃癌细胞SGC-7901中表达的研究

目的通过检测胃癌细胞株SGC-7901和胃黏膜上皮细胞GES-1中SATB1 mRNA和蛋白的表达水平,探讨其在胃癌发展和转移中的作用。方法利用荧光定量PCR、RT-PCR检测胃癌细胞株SGC-7901和胃黏膜上皮细胞GES-1中SATB1 mRNA的转录水平表达,通过免疫荧光染色检测SATB1在两种细胞中的表达差异。结果 SATB1 mRNA在SGC-7901中的表达程度显著高于GES-1细胞,免疫荧光染色显示SATB1在胃癌细胞株的胞浆和胞核内均有分布,呈强阳性染色,而在GES-1细胞中无表达。结论 SATB1在胃癌细胞株SGC-7901中mRNA和蛋白水平均呈现高表达,提示SATB1的表达水平可能与胃癌发生发展密切相关,有望成为判断胃癌预后的一个指标。

Genomics of hepatitis B virus-related hepatocellular carcinoma and adjacent noncancerous tissues with cDNA microarray

Background Hepatocellular carcinoma （HCC） is a common primary cancer frequently associated with hepatitis B virus （HBV） infection. However, whether these identified genes are particularly associated with HBV-related HCC remains unknown. The aim of this study was to investigate the differential gene expression between HBV-related HCC tissues and adjacent noncancerous tissues. Methods cDNA microarray was used to detect the differential gene expression profile in the HBV-related HCC tissues and adjacent noncancerous tissues, and reverse transcription-polymerase chain reaction （RT-PCR） was performed to verify the differential expression of candidate genes obtained from cDNA microarray experiment. Results In this study, 1369 genes or expressed sequence tags （ESTs） including 121 genes or ESTs with at least two-fold expression alterations between cancerous and noncancerous tissues were identified. Special AT-rich sequence binding protein 1 （SATB-1） expression was positive in 73% （16/22） of cancerous tissues and negative （0/22） in all noncancerous tissues of HBV-related HCC patients. Transmembrane 4 superfamily member 1 （TM4SF-1） expression was positive in 86% （19/22） of cancerous tissues and negative （0/22） in all noncancerous tissues. Suppression of tumorigenicity 14 （ST-14） expression was positive in 73% （16/22） of noncancerous tissues in patients with HBV-related HCC and negative in all HCC tissues （0/22）. Conclusion This study provided the gene expression profile of HBV-related HCC and presented differential expression patterns of SATB-1, TM4SF-1 and ST-14 between cancerous and noncancerous tissues in patients with HBV-related HCC.