Control of VEGF expression in triple-negative breast carcinoma cells by suppression of SAF-1 transcription factor activity

Roles of Myc-associated zinc finger protein in malignant tumors

As an important transcription factor that is widely expressed in most tissues of the human body, Myc-associated zinc finger protein (MAZ) has been reported highly expressed in many malignant tumors and thought to be a promising therapeutic target for cancer treatment. In this review, we aim to offer a comprehensive understanding of MAZ regulation in malignant tumors. The carboxy terminal of MAZ protein contains six C2H2 zinc fingers, and its regulation of transcription is based on the interaction between the GC-rich DNA binding sites of target genes and its carboxy-terminal zinc finger motifs. MAZ protein has been found to activate or inhibit the transcriptional initiation process of many target genes, as well as play an important role in the transcriptional termination process of some target genes, so MAZ poses dual regulatory functions in the initiation and termination process of gene transcription. Through the transcriptional regulation of c-myc and Ras gene family, MAZ poses an important role in the occurrence and development of breast cancer, pancreatic cancer, prostate cancer, glioblastoma, neuroblastoma, and other malignant tumors. Our review shows a vital role of MAZ in many malignant tumors and provides novel insight for cancer diagnosis and treatment.

Angioregulatory microRNAs in breast cancer: Molecular mechanistic basis and implications for therapeutic strategies

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Cancer-associated angiogenesis is a fundamental process in tumor growth and metastasis.

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Angioregulatory miRNA–target gene interaction is not only involved in sprouting vessels of breast tumors but also, trans-differentiation of breast cancer cells to endothelial cells in a process termed vasculogenic mimicry.

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Successful targeting of tumor angiogenesis is still a missing link in the treatment of Breast cancer (BC) due to the low effectiveness of anti-angiogenic therapies in this cancer.

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Response to anti-angiogenic therapeutics are controlled by a miRNAs, so the identification of interaction networks of miRNAs–targets can be applicable in determining anti-angiogeneic therapy and new biomarkers in BC.

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Angioregulatory miRNAs in breast cancer cells and their microenvironment have therapeutic potential in cancer treatment.

Background

Cancer-associated angiogenesis is a fundamental process in tumor growth and metastasis. A variety of signaling regulators and pathways contribute to establish neovascularization, among them as small endogenous non-coding RNAs, microRNAs (miRNAs) play prominent dual regulatory function in breast cancer (BC) angiogenesis.

Aim of Review

This review aims at describing the current state-of-the-art in BC angiogenesis-mediated by angioregulatory miRNAs, and an overview of miRNAs dysregulation association with the anti-angiogenic response in addition to potential clinical application of miRNAs-based therapeutics.

Key Scientific Concepts of Review

Angioregulatory miRNA–target gene interaction is not only involved in sprouting vessels of breast tumors but also, trans-differentiation of BC cells to endothelial cells (ECs) in a process termed vasculogenic mimicry. Using canonical and non-canonical angiogenesis pathways, the tumor cell employs the oncogenic characteristics such as miRNAs dysregulation to increase survival, proliferation, oxygen and nutrient supply, and treatment resistance. Angioregulatory miRNAs in BC cells and their microenvironment have therapeutic potential in cancer treatment. Although, miRNAs dysregulation can serve as tumor biomarker nevertheless, due to the association of miRNAs dysregulation with anti-angiogenic resistant phenotype, clinical benefits of anti-angiogenic therapy might be challenging in BC. Hence, unveiling the molecular mechanism underlying angioregulatory miRNAs sparked a booming interest in finding new treatment strategies such as miRNA-based therapies in BC.

Inhibiting Forkhead box K1 induces autophagy to reverse epithelial-mesenchymal transition and metastasis in gastric cancer by regulating Myc-associated zinc finger protein in an acidic microenvironment

Background: Forkhead box K1 (FOXK1) is a transcription factor belonging to the Forkhead box (FOX) family and is closely related to the development of various cancers, but the functional mechanism through which FOXK1 regulates autophagy and epithelial-mesenchymal transition (EMT) in the acidic microenvironment of gastric cancer (GC) remains unclear.

Results: Our results indicated that the inhibition of FOXK1 induced autophagy and thus exerted antimetastatic effects in an acidic microenvironment. The dual inhibition of mammalian target of rapamycin (mTOR) and FOXK1 enhanced autophagy and reversed EMT of acidic GC cells. In addition, FOXK1 activated transcription in conjunction with the MAZ promoter.

Conclusion: Together, our results suggest that FOXK1 can be used as an independent prognostic indicator for GC patients. We also revealed a new strategy involving the cotargeting of FOXK1 and autophagy to reverse the effects of EMT. MAZ is involved in the development and progression of GC as a downstream target of FOXK1.

Methods: Here, the cellular responses to the inhibition of FOXK1 in GC were studied in vivo and in vitro through wound healing assays, transwell assays, Western blotting, laser confocal microscopy and transmission electron microscopy. The molecular mechanisms of FOXK1 and Myc-associated zinc finger protein (MAZ) were studied via chromatin immunoprecipitation sequencing (ChIP-seq), bioinformatics, Western blotting, and quantitative real-time PCR (q-PCR).

The Effects of Trifolium pratense L. Sprouts' Phenolic Compounds on Cell Growth and Migration of MDA-MB-231, MCF-7 and HUVEC Cells

Uncontrolled growth and migration and invasion abilities are common for cancer cells in malignant tumors with low therapeutic effectiveness and high mortality and morbidity. Estrogen receptor β (ERβ), as a member of the nuclear receptor superfamily, shows potent tumor suppressive activities in many cancers. Phytoestrogens’ structural resemblance to 17 β-estradiol allows their binding to ERβ isoform predominantly, and therefore, expression of genes connected with elevated proliferation, motility and invasiveness of cancer cells may be downregulated. Among polyphenolic compounds with phytoestrogenic activity, there are isoflavones from Trifolium pratense L. (red clover) sprouts, containing high amounts of formononetin and biochanin A and their glycosides. To determine the source of the most biologically active isoflavones, we obtained four extracts from sprouts before and after their lactic fermentation and/or β-glucosidase treatment. Our previous results of ITC (isothermal titration calorimetry) modelling and a docking simulation showed clover isoflavones’ affinity to ERβ binding, which may downregulate cancer cell proliferation and migration. Thus, the biological activity of T. pratense sprouts’ extracts was checked under in vitro conditions against highly invasive human breast cancer cell line MDA-MB-231 and non-invasive human breast cancer cell line MCF-7 cells. To compare extracts’ activities acquired for cancer cells with those activities against normal cells, as a third model we choose human umbilical vein endothelial cells (HUVEC), which, due to their migration abilities, are involved in blood vessel formation. Extracts obtained from fermented sprouts at IC₀ dosages were able to inhibit migration of breast cancer cells through their influence on intracellular ROS generation; membrane stiffening; adhesion; regulation of MMP-9, N-cadherin and E-cadherin at transcriptional level; or VEGF secretion. Simultaneously, isolated phenolics revealed no toxicity against normal HUVEC cells. In the manuscript, we proposed a preliminary mechanism accounting for the in vitro activity of Trifolium pratense L. isoflavones. In this manner, T. pratense sprouts, especially after their lactic fermentation, can be considered a potent source of biological active phytoestrogens and a dietary supplement with anti-cancer and anti-invasion properties.

Transcription Factors Involved in Tumorigenesis Are Over-Represented in Mutated Active DNA-Binding Sites in Neuroblastoma

The contribution of coding mutations to oncogenesis has been largely clarified, whereas little is known about somatic mutations in noncoding DNA and their role in driving tumors remains controversial. Here, we used an alternative approach to interpret the functional significance of noncoding somatic mutations in promoting tumorigenesis. Noncoding somatic mutations of 151 neuroblastomas were integrated with ENCODE data to locate somatic mutations in regulatory elements specifically active in neuroblastoma cells, nonspecifically active in neuroblastoma cells, and nonactive. Within these types of elements, transcription factors (TF) were identified whose binding sites were enriched or depleted in mutations. For these TFs, a gene expression signature was built to assess their implication in neuroblastoma. DNA- and RNA-sequencing data were integrated to assess the effects of those mutations on mRNA levels. The pathogenicity of mutations was significantly higher in transcription factor binding site (TFBS) of regulatory elements specifically active in neuroblastoma cells, as compared with the others. Within these elements, there were 18 over-represented TFs involved mainly in cell-cycle phase transitions and 15 under-represented TFs primarily regulating cell differentiation. A gene expression signature based on over-represented TFs correlated with poor survival and unfavorable prognostic markers. Moreover, recurrent mutations in TFBS of over-represented TFs such as EZH2 affected MCF2L and ADP-ribosylhydrolase like 1 expression, among the others. We propose a novel approach to study the involvement of regulatory variants in neuroblastoma that could be extended to other cancers and provide further evidence that alterations of gene expression may have relevant effects in neuroblastoma development. SIGNIFICANCE: These findings propose a novel approach to study regulatory variants in neuroblastoma and suggest that noncoding somatic mutations have relevant implications in neuroblastoma development.

Suppression of vascular endothelial growth factor expression in breast cancer cells by microRNA-125b-mediated attenuation of serum amyloid A activating factor-1 level

Increased level of an inflammation-responsive transcription factor called serum amyloid A-activating factor (SAF-1) has been linked to the pathogenesis in human breast cancer. SAF-1 is found to promote vascular endothelial growth factor (VEGF) expression in breast carcinoma cells and boost angiogenesis. In an effort to develop a cellular mechanism to control VEGF expression, we sought to limit SAF-1 activity in breast cancer cells. We report here several targets within the SAF-1 mRNA for binding of microRNA-125b (miR-125b) and we show that VEGF expression is reduced in breast cancer cells when SAF-1 level is reduced with the microRNA action. Within the 3' un-translated region (UTR) of SAF-1 transcript, we have identified four highly conserved miR-125b responsive elements. We show that these miR-125b binding sites mediate repression of SAF-1 by miR-125b. Ectopic expression of miR-125b in nonmetastatic and metastatic breast cancer cells repressed SAF-1-mediated activity on VEGF promoter function and inhibited cancer cell migration and invasion potentials in vitro. Together, these results suggest that termination of SAF-1 function by miR-125b could be developed as a potential anti-VEGF and anti-angiogenic agent, which has high clinical relevance.

Development of a Biocompatible Copolymer Nanocomplex to Deliver VEGF siRNA for Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is the most difficult breast cancer subtype to treat. TNBC patients have significantly higher expression of vascular endothelial growth factor (VEGF) in tumors compared to non-TNBC patients. VEGF not only exerts its pro-angiogenic effects on endothelial cells but also acts as a survival and autocrine growth factor for VEGF receptor (VEGFR) expressing cancer cells. Silencing the expression of VEGF is therefore a potential therapy for TNBC.

Methods: A novel biocompatible linear copolymer poly[bis(ε-Lys-PEI)Glut-PEG] (PLEGP) was developed to deliver VEGF siRNA for TNBC therapy. The copolymer is composed of lysine and glutaric acid, a natural metabolite of amino acids in the body. Low-molecular weight polyethyleneimine (PEI) was grafted to the copolymer to efficiently condense siRNA into nanocomplex without inducing cytotoxicity. Various in vitro studies were performed to evaluate the stability, cellular uptake, tumor penetration, and biological activities of the VEGF siRNA nanocomplex. The anti-tumor activities of the nanocomplex was also evaluated in an orthotopic TNBC mouse model.

Results: PEIs with different molecular weights were evaluated, and the copolymer PLEGP₁₈₀₀ was able to easily form a stable nanocomplex with siRNAs and protect them from serum degradation. The siRNA/PLEGP₁₈₀₀ nanocomplex exhibited negligible cytotoxicity but showed high cellular uptake, high transfection efficiency, and high tumor penetration. In vitro activity studies showed that the siRNA nanocomplex significantly inhibited migration and invasion of TNBC cells. Moreover, the VEGF siRNA nanocomplex efficiently inhibited tumor growth in an orthotopic TNBC mouse model and down-regulated VEGF expression in the tumor.

Conclusion: PLEGP₁₈₀₀ is a safe and efficient copolymer to deliver siRNAs for TNBC therapy. It could potentially be applied to other cancers by changing the cargo and incorporating tumor-specific ligands.

Revealing the alternative promoter usage of SAF/MAZ gene by bichromatic fluorescent reporter construct

The large-scale identification of putative alternative promoters study shows more than 52% of human genes are regulated by alternative promoters. The human myc-associated zinc finger protein (SAF/MAZ) gene have SAF-1 and SAF-3 variants transcripted from two transcription start sites (TSSs). By using SAF/MAZ promoter as a model, we set up an approach to probe how the alternative promoters are regulated in real time. We have constructed the bichromatic fluorescent reporter driven by SAF/MAZ 5'-proximal promoter plasmids from which transactivation status of SAF-1 and SAF-3 alternative promoter could be monitored by EGFP and DsRed expression respectively. The results showed that the SAF-3 expression is regulated by alternative promoters. When the bichromatic fluorescent reporter was driven by -1692/+277 or -1401/+277 SAF/MAZ promoter the dominant expression of SAF-3 would be observed in comparison with SAF-1 expression. We also identified that Elk-1 is an inhibitory transcription factor for SAF-3 expression. The temporal diversity of SAF-1 and SAF-3 expressions can be observed via bichromatic fluorescent reporters. These imply that the bichromatic fluorescent reporter driven by alternative promoter construct might be a useful tool for decoding the temporal regulatory repertoire of alternative promoter in human genes.

Myc-Associated Zinc Finger Protein Regulates the Proinflammatory Response in Colitis and Colon Cancer via STAT3 Signaling

Myc-associated zinc finger (MAZ) is a transcription factor highly upregulated in chronic inflammatory disease and several human cancers. In the present study, we found that MAZ protein is highly expressed in human ulcerative colitis and colon cancer. However, the precise role for MAZ in the progression of colitis and colon cancer is not well defined. To determine the function of MAZ, a novel mouse model of intestinal epithelial cell-specific MAZ overexpression was generated. Expression of MAZ in intestinal epithelial cells was sufficient to enhance inflammatory injury in two complementary models of colitis. Moreover, MAZ expression increased tumorigenesis in an in vivo model of inflammation-induced colon cancer and was important for growth of human colon cancer cell lines in vitro and in vivo Mechanistically, MAZ is critical in the regulation of oncogenic STAT3 signaling. MAZ-expressing mice have enhanced STAT3 activation in the acute response to colitis. Moreover, MAZ was essential for cytokine- and bacterium-induced STAT3 signaling in colon cancer cells. Furthermore, we show that STAT3 is essential for MAZ-induced colon tumorigenesis using a chemical inhibitor. These data indicate an important functional role for MAZ in the inflammatory progression of colon cancer through regulation of STAT3 signaling and suggest that MAZ is a potential therapeutic target to dampen STAT3 signaling in colon cancer.

Oxidative Stress in Mesenchymal Stem Cell Senescence: Regulation by Coding and Noncoding RNAs

SIGNIFICANCE

Mesenchymal stem cells (MSCs), adult stem cells with the potential of differentiation into mesodermal lineages, play an important role in tissue homeostasis and regeneration. In different organs, a subpopulation of MSCs is located near the vasculature and possibly represents the original source of lineage-committed mesenchymal progenitors. Recent Advances: The plasticity and immune characteristics of MSCs render them a preferential tool for regenerative cell therapy.

CRITICAL ISSUES

The culture expansion needed before MSC transplantation is associated with cellular senescence. Moreover, accelerated senescence of the total and perivascular MSC pool has been observed in humans and mouse models of premature aging disorders. MSC dysfunction is acknowledged as a culprit for the aging-associated degeneration of mesodermal tissues, but the underlying epigenetic pathways remain elusive. This article reviews current understanding of mechanisms impinging on MSC health, including oxidative stress, Nrf2-antioxidant responsive element activity, sirtuins, noncoding RNAs, and PKCs.

FUTURE DIRECTIONS

We provide evidence that epigenetic profiling of MSCs is utilitarian to the prediction of therapeutic outcomes. In addition, strategies that target oxidative stress-associated mechanisms represent promising approaches to counteract the detrimental effect of age and senescence in MSCs.-Antioxid. Redox Signal. 29, 864-879.

Down-regulation of CITED2 attenuates breast tumor growth, vessel formation and TGF-β-induced expression of VEGFA

While we previously demonstrated that CITED2 expression in primary breast tumor tissues is elevated relative to normal mammary epithelium and inversely correlated with patient survival, its functional impact on primary tumor development and progression remained unknown. To address this issue, we examined the effect of CITED2 silencing on the growth of human breast cancer cell lines MDA-MB-231 and MDA-MB-468 following orthotopic administration in vivo. Here, we show that CITED2 silencing significantly attenuated MDA-MB-231 primary tumor growth concordant with reduced tumor vascularization, while MDA-MB-468 primary tumor growth and tumor vascularization remained unaffected. Correspondingly, expression of VEGFA was significantly reduced in shCITED2-expressing MDA-MB-231, but not MDA-MB-468 tumors. Consistent with the observed pattern of vascularization and VEGFA expression, we found that TGF-β stimulation induced expression of VEGFA and enhanced CITED2 recruitment to the VEGFA promoter in MDA-MA-231 cells, while failing to induce VEGFA expression in MDA-MB-468 cells. Further supporting its involvement in TGF-β-induced expression of VEGFA, CITED2 silencing prevented TGF-β induction of VEGFA expression in MDA-MB-231 cells. Collectively, these data indicate that CITED2 regulates primary breast tumor growth, likely by influencing tumor vasculature via TGF-β-dependent regulation of VEGFA.

Antibodies against MYC-Associated Zinc Finger Protein: An Independent Marker in Acute Coronary Syndrome?

Introduction

Atherosclerosis is considered the pathophysiology underlying cardiovascular (CVD), cerebrovascular, and peripheral vascular diseases. Evidence supporting an autoimmune component is emerging, with imaging studies correlating MYC-associated zinc finger protein antibody (MAZ-Ab) optical density (OD) with plaque activity. This study compares MAZ-Ab OD on ELISA testing among patients presenting with acute coronary syndromes (ACSs) to healthy controls and investigates the association of MAZ-Ab to traditional CVD risk factors.

Methods

Patients admitted with ACSs between August 2007 and July 2011 were included. Serum samples taken at presentation were retrospectively tested for MAZ-Ab and compared with serum from healthy volunteers with no CVD risk factors. Large-scale assessment of post-ACS prognostic relevance was performed using the established PLATO cohort.

Results

In total 174 ACS patients and 96 controls were included. Among ACS patients, median MAZ-Ab OD was higher compared with controls (0.46 vs. 0.27; p = 0.001). Although the majority of ACS patients (116/174; 67%) had suffered from a ST-elevation myocardial infarction, no significant differences in MAZ-Ab titers were evident between ACS subtypes (p = 0.682). No associations between MAZ-Ab OD and conventional CVD risk factors were identified. Large-scale testing revealed no prognostic stratification regarding reinfarction (OR 1.04 [95% CI: 0.94–1.16]; p = 0.436).

Conclusion

MAZ-Ab OD was higher or all ACS phenotypes compared with controls. Given current understanding of MAZ-Ab function, these findings support an autoimmune component to CVD independent of conventional risk factors and indeed the extent of end-organ damage.

Angiogenesis and Antiangiogenesis in Triple-Negative Breast cancer

Several data support a central role for angiogenesis in breast cancer growth and metastasis. Observational studies have demonstrated that microvascular density (MVD) is a prognostic factor in invasive breast cancer, whereas others reached the opposite conclusion. Vascular endothelial growth factor is the most important angiogenic factor with proven significance in breast cancer, as it has been assessed in both experimental and clinical studies. Triple-negative breast cancer (TNBC) is a type of breast cancer which lacks estrogen, progesterone, and HER-2/neu receptors. MVD in both basal-like and TNBC is significantly higher than in non–basal-like and non-TNBC. In breast cancer and other malignancies, the development of agents that inhibit tumor angiogenesis has been an active area of investigation. In TNBC, clinical trials combining targeted agents and chemotherapy have failed to show substantial survival improvement. There is evidence that patients with TNBC may have a greater probability of obtaining some kind of clinical efficacy benefit from bevacizumab-based therapy.

miR-34c regulates the permeability of blood-tumor barrier via MAZ-mediated expression changes of ZO-1, occludin, and claudin-5

The purposes of this study were to investigate the potential roles of miR-34c in regulating blood-tumor barrier (BTB) functions and its possible molecular mechanisms. The over-expression of miR-34c significantly impaired the integrity and increased the permeability of BTB, which were detected in an in vitro BTB model by transendothelial electric resistance and horseradish peroxidase flux assays, respectively. Meanwhile, real-time quantitative PCR (qRT-PCR), Western blot and immunofluorescence assays successively demonstrated downregulation of ZO-1, occludin, and claudin-5 and miR-34c silencing uncovered the opposite results. Dual-luciferase reporter assays results revealed myc-associated zinc-finger protein (MAZ) is a target gene of miR-34c. Besides, mRNA and protein expressions of MAZ were reversely regulated by miR-34c. The down-expression of MAZ significantly impaired the integrity and increased the permeability of BTB as well as downregulated the expressions of ZO-1, occludin, and claudin-5. And chromatin immunoprecipitation verified that MAZ interacted with "GGGCGGG," "CCCTCCC," and "GGGAGGG" DNA sequence of ZO-1, occludin, and claudin-5 promoter, respectively. The over-expression or silencing of either miR-34c or MAZ was performed simultaneously to further explore their functional relations, and results elucidated that miR-34c and MAZ displayed reverse regulatory effects on the integrity and permeability of BTB as well as the expressions of ZO-1, occludin, and claudin-5. In conclusion, our present study indicated that miR-34c regulated the permeability of BTB via MAZ-mediated expression changes of ZO-1, occludin, and claudin-5.

Epigenetic profile of human adventitial progenitor cells correlates with therapeutic outcomes in a mouse model of limb ischemia

OBJECTIVE

We investigated the association between the functional, epigenetic, and expressional profile of human adventitial progenitor cells (APCs) and therapeutic activity in a model of limb ischemia.

APPROACH AND RESULTS

Antigenic and functional features were analyzed throughout passaging in 15 saphenous vein (SV)-derived APC lines, of which 10 from SV leftovers of coronary artery bypass graft surgery and 5 from varicose SV removal. Moreover, 5 SV-APC lines were transplanted (8×10(5) cells, IM) in mice with limb ischemia. Blood flow and capillary and arteriole density were correlated with functional characteristics and DNA methylation/expressional markers of transplanted cells. We report successful expansion of tested lines, which reached the therapeutic target of 30 to 50 million cells in ≈10 weeks. Typical antigenic profile, viability, and migratory and proangiogenic activities were conserved through passaging, with low levels of replicative senescence. In vivo, SV-APC transplantation improved blood flow recovery and revascularization of ischemic limbs. Whole genome screening showed an association between DNA methylation at the promoter or gene body level and microvascular density and to a lesser extent with blood flow recovery. Expressional studies highlighted the implication of an angiogenic network centered on the vascular endothelial growth factor receptor as a predictor of microvascular outcomes. FLT-1 gene silencing in SV-APCs remarkably reduced their ability to form tubes in vitro and support tube formation by human umbilical vein endothelial cells, thus confirming the importance of this signaling in SV-APC angiogenic function.

CONCLUSIONS

DNA methylation landscape illustrates different therapeutic activities of human APCs. Epigenetic screening may help identify determinants of therapeutic vasculogenesis in ischemic disease.

Modulating Effect of Enicostemma littorale on the Expression Pattern of Apoptotic, Cell Proliferative, Inflammatory and Angiogenic Markers During 7, 12-Dimethylbenz (a) Anthracene Induced Hamster Buccal Pouch Carcinogenesis

Enicostemma littorale leaves are traditionally used for the treatment of several diseases, including inflammation and cancer. This study has taken effort to explore the antitumor initiating potential of E. littorale leaves (ElELet) by analyzing the expression pattern of apoptotic (p53, Bcl-2 and Bcl-2 associated X-protein), cell-proliferative (cyclin D1 and proliferating cell nuclear antigen), angiogenic (vascular endothelial growth factor), invasive (matrix metalloproteinase-2 and 9), and inflammatory (NF-κB and cyclooxygenase-2) markers during 7, 12-dimethylbenz (a) anthracene (DMBA) induced hamster buccal pouch carcinogenesis. Oral tumors were induced in the buccal pouches of hamsters using the potent site and organ specific carcinogen, DMBA. DMBA application 3 times a week for 14 weeks resulted in tumor formation in the buccal pouches. Hundred percent tumor formations with dysregulation in the expression pattern of apoptotic, cell proliferative, inflammatory, angiogenic, and invasive markers were observed in the buccal pouches of hamsters treated with DMBA alone. ElELet at a dose of 250 mg/kg body weight orally to DMBA treated hamsters significantly prevented the tumor formation as well as corrected the abnormalities in the expression pattern of above mentioned molecular markers. ElELet thus modulated the expression pattern of all the above mentioned molecular markers in favor of the suppression of cell proliferation occurring in DMBA induced hamster buccal pouch carcinogenesis.

Induction of Ras by SAF-1/MAZ through a feed-forward loop promotes angiogenesis in breast cancer

In the majority of breast cancers, overexpression and hyperactivation of Ras in the tumor microenvironment play significant role in promoting cancer cell growth, angiogenesis, and metastasis. We have previously shown that vascular endothelial growth factor (VEGF) expression in triple negative breast cancer cells is regulated, at least in part, by SAF-1 (serum amyloid A activating factor 1) transcription factor. In this study we show that transformation of normal MCF-10A breast epithelial cells by constitutively active, oncogenic Ras, induces the DNA-binding activity and transcription function of SAF-1. Furthermore, we show that inhibition of MEK/MAPK-signaling pathway prevents Ras-mediated activation of SAF-1. Interestingly, silencing of SAF-1 expression in breast cancer cells by SAF-1-specific short hairpin RNAs (shRNAs) significantly reduced H-Ras and K-Ras mRNA level. We show that SAF-1 is a direct transcriptional regulator of H-Ras and K-Ras and overexpression of SAF-1 increases H-Ras and K-Ras gene expression. Chromatin immunoprecipitation (ChIP) analyses demonstrated in vivo interaction of SAF-1 at highly purine-rich sequences present at the proximal promoter region, upstream of the transcription start site, in H-Ras and K-Ras genes. Previous studies have shown that these sequences are nuclease hypersensitive and capable of forming G4 quadruplex structure. Together, our results show the presence of a novel transactivating loop, in which, Ras and SAF-1 are interconnected. These findings will help defining molecular mechanisms of abnormal overexpression of Ras in breast tumors, which seldom show genetic Ras mutations.

Senescence-associated-gene signature identifies genes linked to age, prognosis, and progression of human gliomas

BACKGROUND

Senescence-associated genes (SAGs) are responsible for the senescence-associated secretory phenotype, linked in turn to cellular aging, the aging brain, and the pathogenesis of cancer.

OBJECTIVE

We hypothesized that senescence-associated genes are overexpressed in older patients, in higher grades of glioma, and portend a poor prognosis.

METHODS

Forty-seven gliomas were arrayed on a custom version of the Affymetrix HG-U133+2.0 GeneChip, for expression of fourteen senescence-associated genes: CCL2, CCL7, CDKN1A, COPG, CSF2RB, CXCL1, ICAM-1, IGFBP-3, IL-6, IL-8, SAA4, TNFRSF-11B, TNFSF-11 and TP53. A combined "senescence score" was generated using principal component analysis to measure the combined effect of the senescence-associated gene signature.

RESULTS

An elevated senescence score correlated with older age (r=0.37; P=.01) as well as a higher degree of malignancy, as determined by WHO, histological grade (r=0.49; P<.001). There was a mild association with poor prognosis (P=.06). Gliosarcomas showed the highest scores. Six genes independently correlated with either age (IL-6, TNFRSF-11B, IGFBP-3, SAA4, and COPG), prognosis (IL-6, SAA4), or the grade of the glioma (IL-6, IL-8, ICAM-1, IGFBP-3, and COPG).

CONCLUSION

We report: 1) a novel molecular signature in human gliomas, based on cellular senescence, translating the concept of SAG to human cancer; 2) the senescence signature is composed of genes central to the pathogenesis of gliomas, defining a novel, aggressive subtype of glioma; and 3) these genes provide prognostic biomarkers, as well as targets, for drug discovery and immunotherapy.

Loss of epigenetic Kruppel-like factor 4 histone deacetylase (KLF-4-HDAC)-mediated transcriptional suppression is crucial in increasing vascular endothelial growth factor (VEGF) expression in breast cancer

Vascular endothelial growth factor (VEGF) is recognized as an important angiogenic factor that promotes angiogenesis in a series of pathological conditions, including cancer, inflammation, and ischemic disorders. We have recently shown that the inflammatory transcription factor SAF-1 is, at least in part, responsible for the marked increase of VEGF levels in breast cancer. Here, we show that SAF-1-mediated induction of VEGF is repressed by KLF-4 transcription factor. KLF-4 is abundantly present in normal breast epithelial cells, but its level is considerably reduced in breast cancer cells and clinical cancer tissues. In the human VEGF promoter, SAF-1- and KLF-4-binding elements are overlapping, whereas SAF-1 induces and KLF-4 suppresses VEGF expression. Ectopic overexpression of KLF-4 and RNAi-mediated inhibition of endogenous KLF-4 supported the role of KLF-4 as a transcriptional repressor of VEGF and an inhibitor of angiogenesis in breast cancer cells. We show that KLF-4 recruits histone deacetylases (HDACs) -2 and -3 at the VEGF promoter. Chronological ChIP assays demonstrated the occupancy of KLF-4, HDAC2, and HDAC3 in the VEGF promoter in normal MCF-10A cells but not in MDA-MB-231 cancer cells. Co-transfection of KLF-4 and HDAC expression plasmids in breast cancer cells results in synergistic repression of VEGF expression and inhibition of angiogenic potential of these carcinoma cells. Together these results identify a new mechanism of VEGF up-regulation in cancer that involves concomitant loss of KLF-4-HDAC-mediated transcriptional repression and active recruitment of SAF-1-mediated transcriptional activation.

Myc-associated zinc finger protein (MAZ) is regulated by miR-125b and mediates VEGF-induced angiogenesis in glioblastoma

In patients with glioblastomas, vascular endothelial growth factor (VEGF) is a key mediator of tumor-associated angiogenesis. Glioblastomas are notorious for their capacity to induce neovascularization, driving continued tumor growth. Here we report that miR-125b is down-regulated in glioblastoma-associated endothelial cells, resulting in increased expression of its target, myc-associated zinc finger protein (MAZ), a transcription factor that regulates VEGF. The down-regulation of miR-125b was also observed on exposure of endothelial cells to glioblastoma-conditioned medium or VEGF, resulting in increased MAZ expression. Further analysis revealed that inhibition of MAZ accumulation by miR-125b, or by MAZ-specific shRNAs, attenuated primary human brain endothelial cell migration and tubule formation in vitro, phenomena considered to mimick angiogenic processes in vitro. Moreover, MAZ expression was elevated in brain blood vessels of glioblastoma patients. Altogether these results demonstrate a functional feed-forward loop in glioblastoma-related angiogenesis, in which VEGF inhibits the expression of miR-125b, resulting in increased expression of MAZ, which in its turn causes transcriptional activation of VEGF. This loop is functionally impeded by the VEGF receptor inhibitor vandetanib, and our results may contribute to the further development of inhibitors of tumor-angiogenesis.