The impact of high co-expression of Sp1 and HIF1α on prognosis of patients with hepatocellular cancer

The Loss of an Orphan Nuclear Receptor NR2E3 Augments Wnt/β-catenin Signaling via Epigenetic Dysregulation that Enhances Sp1-β catenin-p300 Interactions in Hepatocellular Carcinoma

The orphan nuclear receptor NR2E3 (Nuclear receptor subfamily 2 group E, Member 3) is an epigenetic player that modulates chromatin accessibility to activate p53 during liver injury. Nonetheless, a precise tumor suppressive and epigenetic role of NR2E3 in hepatocellular carcinoma (HCC) development remains unclear. HCC patients expressing low NR2E3 exhibit unfavorable clinical outcomes, aligning with heightened activation of the Wnt/β-catenin signaling pathway. The murine HCC models utilizing NR2E3 knockout mice consistently exhibits accelerated liver tumor formation accompanied by enhanced activation of Wnt/β-catenin signaling pathway and inactivation of p53 signaling. At cellular level, the loss of NR2E3 increases the acquisition of aggressive cancer cell phenotype and tumorigenicity and upregulates key genes in the WNT/β-catenin pathway with increased chromatin accessibility. This event is mediated through increased formation of active transcription complex involving Sp1, β-catenin, and p300, a histone acetyltransferase, on the promoters of target genes. These findings demonstrate that the loss of NR2E3 activates Wnt/β-catenin signaling at cellular and organism levels and this dysregulation is associated with aggressive HCC development and poor clinical outcomes. In summary, NR2E3 is a novel tumor suppressor with a significant prognostic value, maintaining epigenetic homeostasis to suppress the Wnt/β-catenin signaling pathway that promotes HCC development.

Asiatic acid inhibits osteosarcoma cell migration and invasion via the AKT/Sp1/MMP1 axis

Osteosarcoma is a malignant bone tumor affecting adolescents and children. No effective treatment is currently available. Asiatic acid (AA), a triterpenoid compound found in Centella asiatica, possesses anti-tumor, anti-inflammatory, and anti-oxidant properties in various types of tumor cells. This study aims to determine whether AA exerts antitumor effects in human osteosarcoma cells. Our results indicate that AA does not influence the viability, proliferative rate, or cell cycle phase of human osteosarcoma cells under non-toxic conditions. AA suppressed osteosarcoma cell migration and invasion by down-regulating matrix metalloproteinase 1 (MMP1) expression. Data in the TNMplot database suggested MMP1 expression was higher in osteosarcoma than in normal tissues, with associated clinical significance observed in osteosarcoma patients. Overexpression of MMP1 in osteosarcoma cells reversed the AA-induced suppression of cell migration and invasion. AA treatment decreased the expression of specificity protein 1 (Sp1), while Sp1 overexpression abolished the effect of AA on MMP1 expression and cell migration and invasion. AA inhibited AKT phosphorylation, and treatment with a PI3K inhibitor (wortmannin) increased the anti-invasive effect of AA on osteosarcoma cells via the p-AKT/Sp1/MMP1 axis. Thus, AA exhibits the potential for use as an anticancer drug against human osteosarcoma.

Hepatocellular carcinoma cell-derived exosomal miR-21-5p promotes the polarization of tumor-related macrophages (TAMs) through SP1/XBP1 and affects the progression of hepatocellular carcinoma

BACKGROUND

Tumor-associated macrophages (TAMs) have unique functions in the development of hepatocellular carcinoma (HCC). The tumor microenvironment is in a complex state in chronic disease. As a major participant in tumor-associated inflammation, TAMs have a unique effect on promoting tumor cell proliferation, angiogenesis and immunosuppression. The in-depth study of TAMs has important scientific and clinical value and provides new ideas for the treatment of cancer.

METHODS

Bioinformatics analysis, dual-luciferase reporter assays, RT-qPCR and clinical samples were used to analyze the potential mechanism of the miR-21-5p/SP1/XBP1 molecular axis in HCC. In this study, miR-21-5p was highly expressed in HCC exosomes compared with normal hepatocyte exosomes, and HCC exosomes containing miR-21-5p promoted the proliferation and migration of HCC cells and inhibited cell apoptosis. In addition, this treatment promoted the M2 polarization of macrophages, induced the expression of transcription factor-specific protein 1 (SP1), and inhibited the expression of X-box binding protein 1 (XBP1). However, these expression trends were reversed after inhibition of miR-21-5p expression in exosomes of hepatoma cells, and the effects of exosomal miR-21-5p were partially restored after overexpression of SP1. Animal experiments also verified that exosomal miR-21-5p in HCC cells affected the expression level of the SP1/XBP1 protein and promoted M2 polarization of TAMs.

CONCLUSION

Exosomal miR-21-5p in HCC cells can affect the development of HCC cells by regulating SP1/XBP1 and promoting the M2 polarization of TAMs, thereby affecting the adverse prognostic response of HCC patients.

Specificity Proteins (Sp) and Cancer

The specificity protein (Sp) transcription factors (TFs) Sp1, Sp2, Sp3 and Sp4 exhibit structural and functional similarities in cancer cells and extensive studies of Sp1 show that it is a negative prognostic factor for patients with multiple tumor types. In this review, the role of Sp1, Sp3 and Sp4 in the development of cancer and their regulation of pro-oncogenic factors and pathways is reviewed. In addition, interactions with non-coding RNAs and the development of agents that target Sp transcription factors are also discussed. Studies on normal cell transformation into cancer cell lines show that this transformation process is accompanied by increased levels of Sp1 in most cell models, and in the transformation of muscle cells into rhabdomyosarcoma, both Sp1 and Sp3, but not Sp4, are increased. The pro-oncogenic functions of Sp1, Sp3 and Sp4 in cancer cell lines were studied in knockdown studies where silencing of each individual Sp TF decreased cancer growth, invasion and induced apoptosis. Silencing of an individual Sp TF was not compensated for by the other two and it was concluded that Sp1, Sp3 and Sp4 are examples of non-oncogene addicted genes. This conclusion was strengthened by the results of Sp TF interactions with non-coding microRNAs and long non-coding RNAs where Sp1 contributed to pro-oncogenic functions of Sp/non-coding RNAs. There are now many examples of anticancer agents and pharmaceuticals that induce downregulation/degradation of Sp1, Sp3 and Sp4, yet clinical applications of drugs specifically targeting Sp TFs are not being used. The application of agents targeting Sp TFs in combination therapies should be considered for their potential to enhance treatment efficacy and decrease toxic side effects.

Circular RNA hsa_circ_0062682 Binds to YBX1 and Promotes Oncogenesis in Hepatocellular Carcinoma

Simple Summary

Circular RNA (circRNA) have a role in carcinogenesis in different cancers, also in hepatocellular carcinoma (HCC). The transcriptome analyses of HCC tumours identified an upregulated circRNA hsa_circ_0062682. We show that this circRNA affects several aspects of oncogenesis, which are cell proliferation, migration, and invasion. Using transcriptome analyses we identified modulated signalling pathways and transcription factors, confirming the observed phenotype in cells. We identified Y-box-binding protein 1 (YBX1), a known oncogene and RNA-binding protein, as a binding partner, which was in line with transcriptome analyses. We also identified a cell-specific response to sorafenib after circRNA modulation, which is in line with a heterogeneous molecular pathology of HCC subtypes.

Abstract

Circular RNAs (circRNAs) have been shown to play an important role in the pathogenesis of hepatocellular carcinoma (HCC). By implementing available transcriptomic analyses of HCC patients, we identified an upregulated circRNA hsa_circ_0062682. Stable perturbations of hsa_circ_0062682 in Huh-7 and SNU-449 cell lines influenced colony formation, migration, cell proliferation, sorafenib sensitivity, and additionally induced morphological changes in cell lines, indicating an important role of hsa_circ_0062682 in oncogenesis. Pathway enrichment analysis and gene set enrichment analysis of the transcriptome data from hsa_circ_0062682 knockdown explained the observed phenotypes and exposed transcription factors E2F1, Sp1, HIF-1α, and NFκB1 as potential downstream targets. Biotinylated oligonucleotide pulldown combined with proteomic analyses identified protein interaction partners of which YBX1, a known oncogene, was confirmed by RNA immunoprecipitation. Furthermore, we discovered a complex cell-type-specific phenotype in response to the oncogenic potential of hsa_circ_0062682. This finding is in line with different classes of HCC tumours, and more studies are needed to shed a light on the molecular complexity of liver cancer.

Long non-coding RNA COL4A2-AS1 facilitates cell proliferation and glycolysis of colorectal cancer cells via miR-20b-5p/hypoxia inducible factor 1 alpha subunit axis

Long non-coding RNAs (lncRNAs) have critical functions in tumorigenesis and progression of colorectal cancer (CRC). The role of lncRNA COL4A2-AS1 (COL4A2-AS1) lacks system investigation. The current study comprehensively analyzed the expression, biological functions, and mechanism of COL4A2-AS1 in CRC through performing real-time quantitative PCR (RT-qPCR), Western blot, cell transfection, cell colony assay, MTT assay, flow cytometry and dual-luciferase reporter system assays. A xenograft model of CRC was constructed to further verify the function of COL4A2-AS1 in CRC progression in vivo. The data revealed an upregulated expression of COL4A2-AS1 in CRC tissues and cell lines than paired adjacent tissues and normal cell line. Silencing COL4A2-AS1 inhibited proliferation, aerobic glycolysis, and promoted apoptosis of CRC cells in vivo and in vitro. However, overexpression of COL4A2-AS1 significantly promoted CRC cell proliferation and aerobic glycolysis. In CRC cells, miR-20b-5p was sponged by COL4A2-AS1 and hypoxia-inducible factor 1 alpha subunit (HIF1A). Restoration of HIF1A expression reversed the inhibitory effects of silencing COL4A2-AS1 on aerobic glycolysis and proliferation of CRC cells. The current findings showed that COL4A2-AS1 promoted the proliferation, and aerobic glycolysis of CRC cells potentially through modulating the miR-20b-5p/HIF1A axis.

Long non-coding RNA COL4A2-AS1 facilitates cell proliferation and glycolysis of colorectal cancer cells via miR-20b-5p/hypoxia inducible factor 1 alpha subunit axis

Long non-coding RNAs (lncRNAs) have critical functions in tumorigenesis and progression of colorectal cancer (CRC). The role of lncRNA COL4A2-AS1 (COL4A2-AS1) lacks system investigation. The current study comprehensively analyzed the expression, biological functions, and mechanism of COL4A2-AS1 in CRC through performing real-time quantitative PCR (RT-qPCR), Western blot, cell transfection, cell colony assay, MTT assay, flow cytometry and dual-luciferase reporter system assays. A xenograft model of CRC was constructed to further verify the function of COL4A2-AS1 in CRC progression in vivo. The data revealed an upregulated expression of COL4A2-AS1 in CRC tissues and cell lines than paired adjacent tissues and normal cell line. Silencing COL4A2-AS1 inhibited proliferation, aerobic glycolysis, and promoted apoptosis of CRC cells in vivo and in vitro. However, overexpression of COL4A2-AS1 significantly promoted CRC cell proliferation and aerobic glycolysis. In CRC cells, miR-20b-5p was sponged by COL4A2-AS1 and hypoxia-inducible factor 1 alpha subunit (HIF1A). Restoration of HIF1A expression reversed the inhibitory effects of silencing COL4A2-AS1 on aerobic glycolysis and proliferation of CRC cells. The current findings showed that COL4A2-AS1 promoted the proliferation, and aerobic glycolysis of CRC cells potentially through modulating the miR-20b-5p/HIF1A axis.

Transcription factors specificity protein and nuclear receptor 4A1 in pancreatic cancer

Specificity protein (Sp) transcription factors (TFs) Sp1, Sp3 and Sp4, and the orphan nuclear receptor 4A1 (NR4A1) are highly expressed in pancreatic tumors and Sp1 is a negative prognostic factor for pancreatic cancer patient survival. Results of knockdown and overexpression of Sp1, Sp3 and Sp4 in pancreatic and other cancer lines show that these TFs are individually pro-oncogenic factors and loss of one Sp TF is not compensated by other members. NR4A1 is also a pro-oncogenic factor and both NR4A1 and Sp TFs exhibit similar functions in pancreatic cancer cells and regulate cell growth, survival, migration and invasion. There is also evidence that Sp TFs and NR4A1 regulate some of the same genes including survivin, epidermal growth factor receptor, PAX3-FOXO1, α5- and α6-integrins, β1-, β3- and β4-integrins; this is due to NR4A1 acting as a cofactor and mediating NR4A1/Sp1/4-regulated gene expression through GC-rich gene promoter sites. Several studies show that drugs targeting Sp downregulation or NR4A1 antagonists are highly effective inhibitors of Sp/NR4A1-regulated pathways and genes in pancreatic and other cancer cells, and the triterpenoid celastrol is a novel dual-acting agent that targets both Sp TFs and NR4A1.

SP1 Expression and the Clinicopathological Features of Tumors: A Meta-Analysis and Bioinformatics Analysis

Objective: Specificity protein 1 (SP1) plays a vital role to promote carcinogenesis in a variety of tumors, and its up-regulated expression is reported to be a hinter of poor prognosis of patients. We conducted this meta-analysis to elucidate the clinical significance and prognostic value of SP1 in malignant tumors. Methods: PubMed and Cochrane Library were searched for studies published between January 1, 2000 and June 1, 2020. The combined odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (95% CIs) were used to investigate the correlation of SP1 with clinical behaviors and prognosis in patients with solid tumors. UALCAN was used to conduct bioinformatics analysis. Results: A total of 24 documents involving 2,739 patients were enrolled in our review. The random-effect model was used to perform this analysis due to the high level of heterogeneity. SP1 low expression was not conducive to lymph node metastasis (OR = 0.42; 95% CI: 0.28-0.64; p < 0.05), progression of TNM stage (OR = 0.34; 95% CI: 0.20-0.57; p < 0.05) and tumor infiltration (OR = 0.33; 95% CI: 0.18-0.60; p < 0.05). Elevated SP1 expression was connected with shorter survival time of patients with hepatocellular carcinoma, pancreatic cancer, gastric cancer and esophageal cancer (HR = 1.95; 95% CI: 1.16-3.28; p < 0.05). According to UALCAN database, breast cancer, ovarian cancer, colon cancer and lung adenocarcinoma display an elevated SP1 expression in comparison with normal tissues. Kaplan-Meier survival plots indicate SP1 mRNA level has negative effects on prognosis of liver hepatocellular carcinoma and brain lower grade glioma. Conclusion: SP1 was associated with lymph node metastasis, TNM stage and depth of invasion, and indicated poor clinical outcome, which brought new insights on the potential candidacy of SP1 in clinical usage.

N-Butanol Fraction of Wenxia Formula Extract Inhibits the Growth and Invasion of Non-Small Cell Lung Cancer by Down-Regulating Sp1-Mediated MMP2 Expression

Lung cancer is the most commonly diagnosed cancer and the leading cause of cancer death. It is necessary to develop effective anti-lung cancer therapeutics. Wenxia Formula (WXF), an empirical traditional Chinese herbal formula, has been reported to have significant antitumor activity. In this study, to further clarify the material basis of the anti-tumor effect of WXF, we investigated the cytotoxic effect of the N-butanol fraction of Wenxia Formula extract (NWXF) against two lung cancer and one normal human cell lines. The chemical profile of NWXF was characterized by UPLC/Q-TOF-MS analysis and a total of 201 compounds with mzCloud Best Match of greater than 70 were identified by using the online database mzCloud. To address the functional role of NWXF, we assessed cell proliferation, migration and invasion capabilities. Subcutaneous xenografts were constructed to determine the effect of NWXF in vivo. The results showed that NWXF effectively inhibited the proliferation and migration of non-small cell lung cancer (NSCLC) cells with little toxic effects on human bronchial epithelial cells. Meanwhile, orally administered NWXF exhibited prominent dose-dependent anti-tumor efficacy in vivo. Mechanistically, NWXF significantly downregulated MMP9 and Sp1-mediated MMP2 expression. In conclusion, NWXF might be a promising candidate for treatment of human lung cancer.

Metformin enhances radiosensitivity in hepatocellular carcinoma by inhibition of specificity protein 1 and epithelial-to-mesenchymal transition

Objective

Radiotherapy becomes more and more important in hepatocellular carcinoma (HCC) due to the development of technology, especially in unresectable cases. Metformin has a synergistic benefit with radiotherapy in some cancers, but remains unclear in HCC. This study aims to investigate the effect of metformin on radiosensitivity of HCC cells and the roles of specificity protein 1 (Sp1) as a target of metformin.

Methods

The SMMC-7721 cell line was exposed to various doses of γ-ray irradiation (0, 2, 4, 6, and 8 Gy) and with or without different concentrations of metformin (0, 1, 5, 10, and 20 mM) to measure the radiosensitivity using MTT assay. Flow cytometry was used to determine cell cycle by propidium iodide (PI) staining and apoptosis by Hoechst 33342/PI staining and Annexin V-FITC/PI staining. Real-time polymerase chain reaction and Western blotting were performed to analyze the Sp1 mRNA and protein expressions of Sp1 and epithelial-to-mesenchymal transition (EMT) marker E-cadherin and Vimentin. The invasion capability was measured by the Boyden chamber assay.

Results

In SMMC-7721 cells exposed to irradiation, metformin reduced proliferation and survival cells at various concentrations (0, 1, 5, 10, and 20 mM) and induced cell cycle arrest, apoptosis, and inhibited invasion. In SMMC-7721 cells with irradiation, the mRNA and protein expressions of Sp1 were significantly decreased by metformin as well as a selective Sp1 inhibitor. Metformin attenuated transforming growth factor-β1 induced decrease of E-cadherin and increase of Vimentin proteins.

Conclusion

Metformin demonstrated enhanced radiosensitivity and inhibition of EMT in HCC cells. Sp1 might be a target of metformin in radiosensitization.

HIF1A activates the transcription of lncRNA RAET1K to modulate hypoxia-induced glycolysis in hepatocellular carcinoma cells via miR-100-5p

Hepatocellular carcinoma (HCC) remains the primary cause of cancer-related death. Metabolic change is the major characteristic of cancer. The present study attempted to investigate the regulatory mechanisms of HCC energy metabolism from the perspective of noncoding RNA regulation of HIF1A and LDHA. The expression of miR-100-5p expression was significantly suppressed in HCC tissue samples and HCC cell lines under 1% O₂-induced hypoxia. miR-100-5p overexpression significantly suppressed hypoxia-induced increases in lactate concentration and glucose uptake. Exposure to 1% O₂ induced HIF1A protein and reduced miR-100-5p expression, while HIF1A silencing dramatically rescued miR-100-5p expression upon 1% O₂ exposure. In addition, 1% O₂-induced increases in lactate concentration and glucose uptake were also suppressed by HIF1A silencing. Next, by analyzing available data in TCGA, we found that lncRNA RAET1K was correlated with HIF1A and miR-100-5p.LncRNA RAET1K could downregulate the expression of miR-100-5p by acting as a sponge, while HIF1A bound the lncRNA RAET1K promoter region to activate its transcription. LncRNA RAET1K silencing significantly suppressed HCC cell proliferation and invasion and also suppressed hypoxia-induced increases in lactate concentration and glucose uptake, while miR-100-5p inhibition reversed the effects of lncRNA RAET1K silencing on hypoxia-induced glycolysis in HCC cells. Finally, the expression of HIF1A, lncRNA RAET1K, and LDHA was upregulated in HCC tissue specimens; the expression of miR-100-5p was negatively related to HIF1A, lncRNA RAET1K, and LDHA; and HIF1A, lncRNA RAET1K, and LDHA were positively correlated with each other. In conclusion, the HIF1A/lncRNA RAET1K/miR-100-5p axis modulates hypoxia-induced glycolysis in HCC cells and might affect HCC progression.

MicroRNA-548b inhibits proliferation and invasion of hepatocellular carcinoma cells by directly targeting specificity protein 1

Emerging studies have revealed that microRNAs (miRNAs) are aberrantly expressed in hepatocellular carcinoma (HCC), and the dysregulation of miRNAs exerts crucial roles in the carcinogenesis and development of HCC. Therefore, elucidating the relationship between miRNAs and HCC progression is of great importance to develop novel therapeutic techniques and to improve the prognosis of patients with this malignancy. Recently, miR-548b-3p (miR-548b) has been demonstrated to be a cancer-associated miRNA in tongue squamous cell carcinoma and glioma. However, the expression and function of miR-548b in HCC remain poorly understood. In the present study, it was found that miR-548b is expressed at low levels in HCC tissues and cell lines. Decreased miR-548b expression was found to be positively associated with the clinical features of HCC, including the TNM stage and lymph node metastasis. Functional experiments revealed that upregulation of miR-548b expression decreased proliferation and invasion of HCC cells. Specificity protein 1 (SP1) was verified to be a direct target of miR-548b in HCC cells; as Spearman's correlation analysis identified miR-548b expression to be negatively correlated with that of SP1 expression in HCC tissue specimens. In addition, SP1 inhibition exhibited similar effects as miR-548b overexpression in HCC cells. SP1 reintroduction significantly reversed the suppressive effects of miR-548b upregulation on the proliferation and invasion of HCC cells. In conclusion, the results presented in the present study demonstrated that miR-548b may serve as a tumor suppressive miRNA that inhibits the proliferation and invasion of HCC cells by directly targeting SP1. Consequently, miR-548b can be exploited as a novel therapeutic target for treating patients with HCC in the future, but this needs to be investigated further.

MiR-3662 suppresses hepatocellular carcinoma growth through inhibition of HIF-1α-mediated Warburg effect

Glucose metabolic reprogramming from oxidative to aerobic glycolysis, referred as the Warburg effect, is a hallmark of tumor cells. Accumulating evidence suggests that a subset of microRNAs play pivotal roles in modulating such reprogramming of glucose metabolism in cancer cells. miR-3662 has been implicated previously in both pro-tumorigenic and anti-tumorigenic effects in several types of cancer. The expression level of miR-3662 is downregulated in acute myeloid leukemia, whereas increased miR-3662 expression is observed in lung adenocarcinoma. However, the roles and underlying mechanisms of miR-3662 in hepatocellular carcinoma (HCC) metabolic reprogramming remain unclear. Our present study revealed that miR-3662 was frequently downregulated in HCC tissues and cell lines. The low expression level of miR-3662 was associated with tumor size, tumor multiplicity, Edmondson grade, and tumor-node-metastasis stage. Gain-of-function and loss-of-function assays showed that miR-3662 dampened glycolysis by reducing lactate production, glucose consumption, cellular glucose-6-phosphate level, ATP generation, and extracellular acidification rate, and increasing oxygen consumption rate in HCC cells after treatment with the hypoxia mimetic CoCl₂. Moreover, miR-3662 suppressed cell growth in vitro and in vivo, and induced G1/S cell cycle arrest. miR-3662 inhibited the activation of ERK and JNK signaling pathways in HCC. By combined computational and experimental approaches, hypoxia-inducible factor-1α (HIF-1α) was determined as a direct target of miR-3662. After treatment with the hypoxia mimetic CoCl₂, miR-3662 regulated the Warburg effect and HCC progression via decreasing HIF-1α expression. Our findings uncover a mechanistic role for miR-3662/HIF-1α axis in HCC metabolic reprogramming, providing a potential therapeutic strategy in liver cancer.

Specificity Protein Transcription Factors and Cancer: Opportunities for Drug Development

Specificity protein (Sp) transcription factors (TFs) such as Sp1 are critical for early development but their expression decreases with age and there is evidence that transformation of normal cells to cancer cells is associated with upregulation of Sp1, Sp3, and Sp4, which are highly expressed in cancer cells and tumors. Sp1 is a negative prognostic factor for pancreatic, colon, glioma, gastric, breast, prostate, and lung cancer patients. Functional studies also demonstrate that Sp TFs regulate genes responsible for cancer cell growth, survival, migration/invasion, inflammation and drug resistance, and Sp1, Sp3 and Sp4 are also nononcogene addiction (NOA) genes and important drug targets. The mechanisms of drug-induced downregulation of Sp TFs and pro-oncogenic Sp-regulated genes are complex and include ROS-dependent epigenetic pathways that initially decrease expression of the oncogene cMyc. Many compounds such as curcumin, aspirin, and metformin that are active in cancer prevention also exhibit chemotherapeutic activity and these compounds downregulate Sp TFs in cancer cell lines and tumors. The effects of these compounds on downregulation of Sp TFs in normal cells and the contribution of this response to their chemopreventive activity have not yet been determined. Cancer Prev Res; 11(7); 371-82. ©2018 AACR.

Targeting specificity protein 1 transcription factor and survivin using tolfenamic acid for inhibiting Ewing sarcoma cell growth

Transcription factor Specificity protein 1 (Sp1) and its downstream target survivin (inhibitor of apoptosis protein), play major roles in the pathogenesis of various cancers. Ewing Sarcoma (ES) is a common soft tissue/bone tumor in adolescent and young adults. Overexpression of survivin is also linked to the aggressiveness and poor prognosis of ES. Small molecule Tolfenamic acid (TA) inhibits Sp1 and survivin in cancer cells. In this investigation, we demonstrate a strategy to target Sp1 and survivin using TA and positive control Mithramycin A (Mit) to inhibit ES cell growth. Knock down of Sp1 using small interfering RNA (siRNA) resulted in significant (p < 0.05) inhibition of CHLA-9 and TC-32 cell growth as assessed by CellTiter-Glo assay kit. TA or Mit treatment caused dose/time-dependent inhibition of cell viability, and this inhibition was correlated with a decrease in Sp1 and survivin protein levels in ES cells. Quantitative PCR results showed that Mit treatment decreased the mRNA expression of both survivin and Sp1, whereas TA diminished only survivin but not Sp1. Proteasome inhibitor restored TA-induced inhibition of Sp1 protein expression suggesting that TA might cause proteasome-dependent degradation. Gel shift assay using ES cell nuclear extract and biotinylated Sp1 consensus oligonucleotides confirmed that both TA and Mit decreased DNA-binding activity of Sp1. These results demonstrate that both Mit and TA reduce expression of Sp1 and survivin, disrupt Sp1 DNA-binding and inhibit ES cell proliferation. This investigation suggests that targeting Sp1 and survivin could be an effective strategy for inhibiting ES cell growth.

Dietary restriction protects against diethylnitrosamine-induced hepatocellular tumorigenesis by restoring the disturbed gene expression profile

Hepatocellular carcinoma (HCC) is one of the most lethal and prevalent malignancies, worse still, there are very limited therapeutic measures with poor clinical outcomes. Dietary restriction (DR) has been known to inhibit spontaneous and induced tumors in several species, but the mechanisms are little known. In the current study, by using a diethylnitrosamine (DEN)-induced HCC mice model, we found that DR significantly reduced the hepatic tumor number and size, delayed tumor development, suppressed proliferation and promoted apoptosis. Further transcriptome sequencing of liver tissues from the DEN and the DEN accompanied with DR (DEN+DR) mice showed that DEN induced profound changes in the gene expression profile, especially in cancer-related pathways while DR treatment reversed most of the disturbed gene expression induced by DEN. Finally, transcription factor enrichment analysis uncovered the transcription factor specificity protein 1 (SP1) probably functioned as the main regulator of gene changes, orchestrating the protective effects of DR on DEN induced HCC. Taken together, by the first comprehensive transcriptome analysis, we elucidate that DR protects aginst DEN-induced HCC by restoring the disturbed gene expression profile, which holds the promise to provide effective molecular targets for cancer therapies.