6667

SP1

Sp1 transcription factor;SP1;Sp1 transcription factor

specificity protein 1|transcription factor Sp1

12q13.1

protein-coding

BACKGROUND & OBJECTIVE: Transcriptional factor Sp1 is involved in many biological processes, such as cell proliferation, apoptosis, differentiation and transformation, and plays an important role in invasion and metastasis of tumors. However, the expression patterns of Sp1 in various tumors are different. This study was to investigate the correlations of Sp1 expression to metastasis, invasion, and prognosis of breast cancer. METHODS: The expression of Sp1 in 60 specimens of breast cancer and 12 specimens of adjacent breast tissue was detected by EnVision immunohistochemistry. Its correlation to clinicopathologic features of breast cancer was analyzed by Cox regression analysis. RESULTS: The positive rate of Sp1 was 71.67% in breast cancer tissues, and 33.33% in adjacent tissues. Sp1 staining in cancer tissue was positively correlated to TNM stage (r=0.349, P<0.05), tumor invasion (r=0.407, P<0.01), and lymph node metastasis (r=0.314, P<0.05). Univariate analysis indicated that the overall survival rate was significantly lower in Sp1-positive patients than in Sp1-negative patients (41.86% vs. 82.35%, P<0.05). Cox multivariate analysis showed that Sp1 expression, TNM stage, invasion and lymph node metastasis were independent prognostic factors of breast cancer. CONCLUSIONS: Sp1 maybe participate in the invasion and metastasis of breast cancer, and is one of the valuable markers indicating poor prognosis of breast cancer. Sp1 detection, with consideration of tumor invasion and clinical stage, may increase the accuracy of predicting prognosis of patients with breast cancer.

Up-regulation of cyclooxygenase-2 (COX-2) is frequently found in human cancers and is significantly associated with tumor metastasis. Our previous results demonstrate that COX-2 and its metabolite prostaglandin E2 (PGE2) stimulate the expression of CCR7 chemokine receptor via EP2/EP4 receptors to promote lymphatic invasion in breast cancer cells. In this study, we address the underlying mechanism of COX-2/PGE2-induced CCR7 expression. We find that COX-2/PGE2 increase CCR7 expression via the AKT signaling pathway in breast cancer cells. Promoter deletion and mutation assays identify the Sp1 site located at the -60/-57 region of CCR7 gene promoter is critical for stimulation. Chromatin immunoprecipitation (ChIP) assay confirms that in vivo binding of Sp1 to human CCR7 promoter is increased by COX-2 and PGE2. Knockdown of Sp1 by shRNA reduces the induction of CCR7 by PGE2. We demonstrate for the first time that AKT may directly phosphorylate Sp1 at S42, T679, and S698. Phosphorylation-mimic Sp1 protein harboring S42D, T679D, and S698D mutation strongly activates CCR7 expression. In contrast, change of these three residues to alanine completely blocks the induction of CCR7 by PGE2. Pathological investigation demonstrates that CCR7 expression is strongly associated with phospho-AKT and Sp1 in 120 breast cancer tissues. Collectively, our results demonstrate that COX-2 up-regulates CCR7 expression via AKT-mediated phosphorylation and activation of Sp1 and this pathway is highly activated in metastatic breast cancer.

Breast cancer is the most common cancer in women for which the metastatic process is still poorly understood. CD147 is upregulated in breast cancer and has been associated with tumor progression, but little is known about its regulatory mechanisms. In this study, we demonstrated that CD147 was overexpressed in breast cancer tissues and cell lines, and the high expression correlated with tumor invasion and metastasis. We also found that the transcription factors Sp1 and c-Myc could bind to the CD147 promoter and enhance its expression. The CD147 mRNA has a 748-bp 3'-untranslated region (UTR) with many miRNA target sites, suggesting possible regulation by miRNAs. We discovered that miR-22 repressed CD147 expression by directly targeting the CD147 3'UTR. We also determined that miR-22 could indirectly participate in CD147 modulation by downregulating Sp1 expression. miR-22 could form an autoregulatory loop with Sp1, which repressed miR-22 transcription by binding to the miR-22 promoter. Together with the c-Myc-mediated inhibition of miR-22 expression, our investigation identified a miR-22/Sp1/c-Myc network that regulates CD147 gene transcription. In addition, miR-22 overexpression suppressed breast cancer cell invasion, metastasis, and proliferation by targeting CD147 in vitro and in vivo. Furthermore, we found that miR-22 was significantly downregulated in breast cancer tissues and that its expression was inversely correlated with the tumor-node-metastasis stage and lymphatic metastasis in patients. Our study provides the first evidence that an miR-22/Sp1/c-Myc network regulates CD147 upregulation in breast cancer and that miR-22 represses breast cancer invasive and metastatic capacities.

BACKGROUND: Osteopontin (OPN) mediates cancer metastasis. Mechanisms regulating OPN expression in human colorectal cancer are unknown. Using SW480 colon adenocarcinoma cells, we hypothesized that transcription determines OPN expression. METHODS: SW480 constitutively express OPN. Transient transfection and deletion analysis of human OPN promoter (full-length 2.1 kb)-luciferase constructs identified cis-regulatory regions. Gelshift and chromatin immunoprecipitation (ChIP) assays identified the trans-regulatory nuclear protein. Using in vitro adhesion, migration, and invasion studies, siRNA was used to determine the functional effect of decreased nuclear protein expression. RESULTS: A cis-regulatory promoter region, nt-80 to nt-108, upregulated OPN transcription. Gelshift assays demonstrated specific binding of nuclear proteins. Competition with unlabeled mutant oligonucleotides indicated that the region, nt-94 to nt-104 (TGGGCTGGGC), was essential for protein binding in gelshift assays. Confirmatory ChIP assays showed the corresponding nuclear protein to be Sp1. Sp1 expression was ablated with siRNA (si-Sp1), resulting in decreased OPN-dependent adhesion, migration, and invasion by 50%, 70%, and 65%, respectively. Exogenous addition of OPN to si-Sp1 cells restored adhesion, migration, and invasion indices. CONCLUSIONS: In SW480 human colon cancer cells, we conclude that Sp1 mediated expression of the tumor metastasis protein, OPN, regulates in vitro functional correlates of tumor metastasis.

OBJECTIVE: To investigate the expression of transcription factor SP1, vascular endothelial growth factor(VEGF) and CD34 in serosa-infiltrating gastric cancer and their relationship with biological behavior and survival rate. METHODS: Immunohistochemical technique was used to detect the expression of SP1, VEGF and CD34(described by microvessel density, MVD) in 68 specimens with serosa-infiltrating gastric cancer. RESULTS: The positive expression rates of SP1 and VEGF in serosa-infiltrating gastric cancer were 50.0% and 52.9% respectively. In positive SP1 specimens, the positive rate of VEGF(73.5%) was significantly higher than that of negative SP1 specimens (32.4%, chi(2)=11.57, P=0.01). The mean tumor MVD was correlated with the expression levels of SP1 and VEGF(P<0.01). There was a significant correlation of the SP1 expression with tumor size and growth pattern(P =0.01). The expression levels of VEGF and MVD were correlated with Borrmann types, cell differentiation, metastatic lymph nodes and growth pattern(P<0.01). Univariate analysis revealed that SP1 and VEGF expression, MVD, Borrmann types, lymph node metastasis, tumor size and growth pattern were significant prognostic factors related to survival time. Multivariate analysis showed that SP1 expression, MVD and growth pattern were independently prognostic factors of poor survival. CONCLUSIONS: The activation of SP1 contributes to angiogenesis and metastasis in gastric cancer through the up-regulation of VEGF. SP1, VEGF and MVD may serve as valuable indicators of biological behavior of gastric cancer. SP1 protein expression is not related with the number of metastatic lymph nodes. SP1 expression and MVD may serve as valuable indicators of prognosis in gastric carcinoma.

Specificity protein 1 (SP1) is an essential transcription factor that regulates multiple cancer-related genes. Because aberrant expression of SP1 is related to cancer development and progression, we focused on SP1 expression in gastric carcinoma and its correlation with disease outcomes. Although patient survival decreased as SP1 expression increased (P<0.05) in diffuse-type gastric cancer, the lack of SP1 expression in intestinal-type gastric cancer was significantly correlated with poor survival (P<0.05). The knockdown of SP1 in a high SP1-expressing intestinal-type gastric cell line, MKN28, increased migration and invasion but decreased proliferation. Microarray data in SP1 siRNA-transfected MKN28 revealed that the genes inhibiting migration were downregulated, whereas the genes negatively facilitating proliferation were increased. However, both migration and invasion were decreased by forced SP1 expression in a low SP1-expressing intestinal-type gastric cell line, AGS. Unlike the intestinal-type, in a high SP1-expressing diffuse-type gastric cell line, SNU484, migration and invasion were decreased by SP1 siRNA. In contrast to previous studies that did not identify differences between the 2 histological types, our results reveal that low expression of SP1 is involved in cancer progression and metastasis and differentially affects intestinal-type compared with diffuse-type gastric adenocarcinoma.

BACKGROUND: The mortality and morbidity rates from cancer metastasis have not declined in Taiwan, especially because of hepatocellular carcinoma (HCC). Resveratrol has been shown to have benefits such as cardioprotection, providing antioxidative, anti-inflammatory, anti-cancer properties in previous studies. Therefore, HCC cells were subjected to treatment with resveratrol and then analyzed to determine the effects of resveratrol on the migration and invasion. METHODOLOGY AND PRINCIPAL FINDINGS: Modified Boyden chamber assays revealed that resveratrol treatment significantly inhibited cell migration and invasion capacities of Huh7 cell lines that have low cytotoxicity in vitro, even at a high concentration of 100 microM. The results of casein zymography and western blotting revealed that the activities and protein levels of the urokinase-type plasminogen activator (u-PA) were inhibited by resveratrol. Western blot analysis also showed that resveratrol inhibits phosphorylation of JNK1/2. Tests of the mRNA level, real-time PCR, and promoter assays evaluated the inhibitory effects of resveratrol on u-PA expression in HCC cells. The chromatin immunoprecipitation (ChIP) assay showed that reactive in transcription protein of nuclear factor SP-1 was inhibited by resveratrol. CONCLUSIONS: Resveratrol inhibits u-PA expression and the metastasis of HCC cells and is a powerful chemopreventive agent. The inhibitory effects were associated with the downregulation of the transcription factors of SP-1 signaling pathways.

Loss of the metastasis suppressor gene, KiSS-1 has been strongly correlated to the progression of metastases in numerous types of cancers. The mechanism through which KiSS-1 is lost during metastasis, however, is still not completely known. Previous studies have shown that genetic material on human chromosome 6q16.3-q23 is essential for KiSS-1 expression in normal tissues. Additionally, microcell-mediated transfer of this chromosome in cancerous tissue results in rescued expression of KiSS-1 and reduced metastatic phenotype. Here, we show that loss of Sp1-coactivator protein DRIP-130, which is encoded by human chromosome 6q16.3-q23, results in reduced KiSS-1 promoter activation in highly malignant melanoma cells. Co-expression of Sp1 and DRIP-130 not only rescues KiSS-1 expression, but also induces an inhibition of the invasive and migratory behavior in highly metastatic melanoma cells, similar to the overexpression of KiSS-1 metastasis suppressor gene in those cells. Furthermore, we demonstrate that KiSS-1 expression is regulated by Sp1 elements within the first 100-bp region of the KiSS-1 promoter and that targeted deletion of a single GC-rich region spanning -93 to -58 interrupts Sp1- and DRIP-130-modulated transcriptional control of KiSS-1 expression. Our results thus suggest that DRIP-130 is a key regulator in KiSS-1 transactivation in normal tissue, and that the loss of DRIP-130 expression, as a result of the gross loss of human chromosome 6q16.3-q23, provokes increased tumor metastasis.

cancer metastasis involves multistep adhesive interactions between tumor cells (TCs) and endothelial cells (ECs), but the molecular mechanisms of intercellular communication in the tumor microenvironment remain elusive. Using static and flow coculture systems in conjunction with flow cytometry, we discovered that certain receptors on the ECs are upregulated on melanoma cell adhesion. Direct contact but not separate coculture between human umbilical endothelial cells (HUVECs) and a human melanoma cell line (Lu1205) increased intercellular adhesion molecule 1 (ICAM-1) and E-selectin expression on HUVECs by 3- and 1.5-fold, respectively, compared with HUVECs alone. The nonmetastatic cell line WM35 failed to promote ICAM-1 expression changes in HUVECs on contact. Enzyme-linked immunosorbent assay (ELISA) revealed that EC-TC contact has a synergistic effect on the expression of the cytokines interleukin (IL)-8, IL-6, and growth-related oncogene alpha (Gro-alpha). By using E-selectin cross-linking and beads coated with CD44 immunopurified from Lu1205 cells, we showed that CD44/selectin ligation was responsible for the ICAM-1 up-regulation on HUVECs. Protein kinase Calpha (PKC-alpha) activation was found to be the downstream target of the CD44/selectin-initiated signaling, as ICAM-1 elevation was inhibited by siRNA targeting PKCalpha or a dominant negative form of PKCalpha (PKCalpha DN). Western blot analysis and electrophoretic mobility shift assays (EMSAs) showed that TC-EC contact mediated p38 phosphorylation and binding of the transcription factor SP-1 to its regulation site. In conclusion, CD44/selectin binding signals ICAM-1 up-regulation on the EC surface through a PKCalpha-p38-SP-1 pathway, which further enhances melanoma cell adhesion to ECs during metastasis.