Ets-1 upregulates matrix metalloproteinase-1 expression through extracellular matrix adhesion in vascular endothelial cells

Hypoxic Effects on Matrix Metalloproteinases' Expression in the Tumor Microenvironment and Therapeutic Perspectives

The tumor microenvironment (TME) is characterized by an acidic pH and low oxygen concentrations. Hypoxia induces neoplastic cell evasion of the immune surveillance, rapid DNA repair, metabolic reprogramming, and metastasis, mainly as a response to the hypoxic inducible factors (HIFs). Likewise, cancer cells increase matrix metalloproteinases' (MMPs) expression in response to TME conditions, allowing them to migrate from the primary tumor to different tissues. Since HIFs and MMPs are augmented in the hypoxic TME, it is easy to consider that HIFs participate directly in their expression regulation. However, not all MMPs have a hypoxia response element (HRE)-HIF binding site. Moreover, different transcription factors and signaling pathways activated in hypoxia conditions through HIFs or in a HIF-independent manner participate in MMPs' transcription. The present review focuses on MMPs' expression in normal and hypoxic conditions, considering HIFs and a HIF-independent transcription control. In addition, since the hypoxic TME causes resistance to anticancer conventional therapy, treatment approaches using MMPs as a target alone, or in combination with other therapies, are also discussed.

Matrix Metalloproteinases Inhibitors in Cancer Treatment: An Updated Review (2013-2023)

Matrix metalloproteinases (MMPs) are identifiable members of proteolytic enzymes that can degrade a wide range of proteins in the extracellular matrix (ECM). MMPs can be categorized into six groups based on their substrate specificity and structural differences: collagenases, gelatinases, stromelysins, matrilysins, metalloelastase, and membrane-type MMPs. MMPs have been linked to a wide variety of biological processes, such as cell transformation and carcinogenesis. Over time, MMPs have been evaluated for their role in cancer progression, migration, and metastasis. Accordingly, various MMPs have become attractive therapeutic targets for anticancer drug development. The first generations of broad-spectrum MMP inhibitors displayed effective inhibitory activities but failed in clinical trials due to poor selectivity. Thanks to the evolution of X-ray crystallography, NMR analysis, and homology modeling studies, it has been possible to characterize the active sites of various MMPs and, consequently, to develop more selective, second-generation MMP inhibitors. In this review, we summarize the computational and synthesis approaches used in the development of MMP inhibitors and their evaluation as potential anticancer agents.

The role of cancer-associated fibroblasts in tumorigenesis of gastric cancer

Despite advances in anticancer therapy, the prognosis of gastric cancer (GC) remains unsatisfactory. Research in recent years has shown that the malignant behavior of cancer is not only attributable to tumor cells but is partly mediated by the activity of the cancer stroma and controlled by various molecular networks in the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are one of the most abundant mesenchymal cell components of the stroma and extensively participate in the malignant development of GC malignancy. CAFs modulate the biological properties of tumor cells in multiple ways, including the secretion of various bioactive molecules that have effects through paracrine and autocrine signaling, the release of exosomes, and direct interactions, thereby affecting GC initiation and development. However, there is marked heterogeneity in the cellular origins, phenotypes, and functions of CAFs in the TME of GC. Furthermore, variations in factors, such as proteins, microRNAs, and lncRNAs, affect interactions between CAFs and GC cells, although, the potential molecular mechanisms are still poorly understood. In this review, we aim to describe the current knowledge of the cellular features and heterogeneity of CAFs and discuss how these factors are regulated in CAFs, with a focus on how they affect GC biology. This review provides mechanistic insight that could inform therapeutic strategies and improve the prognosis of GC patients.

Endothelial loss of Fzd5 stimulates PKC/Ets1-mediated transcription of Angpt2 and Flt1

Aims

Formation of a functional vascular system is essential and its formation is a highly regulated process initiated during embryogenesis, which continues to play important roles throughout life in both health and disease. In previous studies, Fzd5 was shown to be critically involved in this process and here we investigated the molecular mechanism by which endothelial loss of this receptor attenuates angiogenesis.

Methods and results

Using short interference RNA-mediated loss-of-function assays, the function and mechanism of signaling via Fzd5 was studied in human endothelial cells (ECs). Our findings indicate that Fzd5 signaling promotes neovessel formation in vitro in a collagen matrix-based 3D co-culture of primary vascular cells. Silencing of Fzd5 reduced EC proliferation, as a result of G₀/G₁ cell cycle arrest, and decreased cell migration. Furthermore, Fzd5 knockdown resulted in enhanced expression of the factors Angpt2 and Flt1, which are mainly known for their destabilizing effects on the vasculature. In Fzd5-silenced ECs, Angpt2 and Flt1 upregulation was induced by enhanced PKC signaling, without the involvement of canonical Wnt signaling, non-canonical Wnt/Ca²⁺-mediated activation of NFAT, and non-canonical Wnt/PCP-mediated activation of JNK. We demonstrated that PKC-induced transcription of Angpt2 and Flt1 involved the transcription factor Ets1.

Conclusions

The current study demonstrates a pro-angiogenic role of Fzd5, which was shown to be involved in endothelial tubule formation, cell cycle progression and migration, and partly does so by repression of PKC/Ets1-mediated transcription of Flt1 and Angpt2.

Electronic supplementary material

The online version of this article (10.1007/s10456-018-9625-6) contains supplementary material, which is available to authorized users.

Ets-1 promoter-associated noncoding RNA regulates the NONO/ERG/Ets-1 axis to drive gastric cancer progression

Emerging studies have indicated the essential functions of long noncoding RNAs (lncRNAs) during cancer progression. However, whether lncRNAs contribute to the upregulation of v-ets erythroblastosis virus E26 oncogene homolog 1 (Ets-1), an established oncogenic protein facilitating tumor invasion and metastasis, in gastric cancer remains elusive. Herein, we identified Ets-1 promoter-associated noncoding RNA (pancEts-1) as a novel lncRNA associated with the gastric cancer progression via mining of publicly available datasets and rapid amplification of cDNA ends. RNA pull-down, RNA immunoprecipitation, in vitro binding, and RNA electrophoretic mobility shift assays indicated the binding of pancEts-1 to non-POU domain containing octamer binding (NONO) protein. Mechanistically, pancEts-1 facilitated the physical interaction between NONO and Ets related gene (ERG), resulting in increased ERG transactivation and transcription of Ets-1 associated with gastric cancer progression. In addition, pancEts-1 facilitated the growth and aggressiveness of gastric cancer cells via interacting with NONO. In gastric cancer tissues, pancEts-1, NONO, and ERG were upregulated and significantly correlated with Ets-1 levels. High levels of pancEts-1, NONO, ERG, or Ets-1 were respectively associated with poor survival of gastric cancer patients, whereas simultaneous expression of all of them (HR = 3.012, P = 0.105) was not an independent prognostic factor for predicting clinical outcome. Overall, these results demonstrate that lncRNA pancEts-1 exhibits oncogenic properties that drive the progression of gastric cancer via regulating the NONO/ERG/Ets-1 axis.

miR-506 Inhibits Epithelial-to-Mesenchymal Transition and Angiogenesis in Gastric Cancer

Gastric cancer is one of the most common malignancies in developing countries. We examined the possible role of miR-506 in gastric cancer, investigated its associations with the clinical outcomes of gastric cancer patients, and explored its potential role in angiogenesis and the metastasis of gastric cancer cells. We found that miR-506 expression was a useful marker for stratifying patients from early to advanced clinical stages and for overall survival prediction. miR-506 overexpression inhibited the epithelial-to-mesenchymal transition of gastric cancer cells; however, depletion of miR-506 promoted it. In addition, miR-506 suppressed gastric cancer angiogenesis and was associated with decreased matrix metalloproteinase-9 expression. We also found that ETS1 was a miR-506 target, and it was expressed in 71.10% of gastric cancer tissue samples. Moreover, ETS1 expression was associated with matrix metalloproteinase-9 expression (P < 0.001). In conclusion, miR-506 was identified as an ETS1 targeting suppressor of metastatic invasion and angiogenesis in gastric cancer.

The impact of Ets-1 oncoprotein and human endoglin (CD105) on the recurrence of non-melanoma skin cancers

BACKGROUND

The aim of this study was to investigate if the expression of CD105 and Ets-1 was predictive of aggressive biologic behavior of non-melanoma skin cancers (NMSC) and to evaluate indicators of local recurrence.

PATIENTS AND METHODS

A total of 144 patients with NMSC were included in the current study. Surgical specimens were independently examined for diagnosis confirmation and immunohistochemical expression of Ets-1 and CD105 by two dermatopathologists.

RESULTS

The most common tumor type was basal cell carcinoma (n = 76), followed by squamous cell carcinomas (SCC) (n = 65). The most common anatomic location was the head and neck area (n = 115). The follow-up was ˃ 2 years in all examined cases. A statistically significant correlation was found between tumor local recurrence and age (P = 0.03), Ets-1 expression (P ˂ 0.0001) and CD105 expression (P ˂ 0.0001).

CONCLUSIONS

Our data confirm that both Ets-1 and CD105 show promise as prognostic markers for local recurrence of NMSC. However, this statement is made with caution, and additional studies, with larger populations, are necessary to examine the correlation between these two markers and local recurrence. A better understanding of the pathogenesis of local recurrence in primary NMSC may result in potential therapeutic interventions.

Transcriptional silencing of ETS-1 abrogates epithelial-mesenchymal transition resulting in reduced motility of pancreatic cancer cells

v-ets erythroblastosis virus E26 oncogene homolog 1 (ETS-1) plays crucial roles in a spectrum of malignancies. ETS-1 has gained attention in cancer research for its importance in cell migration, invasion and proliferation. In the present study, we focused on the effect of ETS-1 on epithelial-mesenchymal transition (EMT), which is characterized by reduced E-cadherin expression and increased N-cadherin expression. We found that ETS-1 mRNA expression was positively correlated with N-cadherin and negatively correlated with E-cadherin mRNA expression in five pancreatic cancer cell lines. To elucidate the functionality of ETS-1 on EMT in pancreatic cancer cells, we constructed a green fluorescent protein (GFP)-expressing plasmid carrying ETS-1 short hairpin RNA (shRNA), and transfected Panc-1 cells with the plasmid. We detected reduced N-cadherin and vascular endothelial growth factor yet higher E-cadherin expression in the ETS-1-silenced cells compared with the control group. In addition, we observed reduced cell migration and increased adhesion in these cells. Our data showed that ETS-1 actively functioned as a regulator of EMT in Panc-1 cells, and provide additional evidence supporting a fundamental role for ETS-1 in metastatic pancreatic cancer cells. These results suggest that analysis of ETS-1 expression levels may provide an avenue for evaluating prognosis in pancreatic cancer.

MicroRNA-1 and microRNA-499 downregulate the expression of the ets1 proto-oncogene in HepG2 cells

MicroRNAs may function to promote or suppress tumor development, depending on the cellular context. The important role of microRNAs in regulating molecular pathways underlying tumorigenesis has been emphasized in hepatocellular carcinoma (HCC). MicroRNAs regulate gene expression via post-transcriptional mechanisms by inhibiting translation or by degrading mRNA. In this study, we show that microRNA-1 (miR-1) and microRNA-499 (miR-499) are capable of repressing the expression of the ets1 proto-oncogene, which plays a fundamental role in the extracellular matrix (ECM) degradation, a process required for tumor cell invasion and migration. We used luciferase reporter assays to demonstrate that miR-1 and miR-499 target the 3' untranslated region (UTR) of ets1. Overexpression of miR-1 and miR-499 in HepG2 cells led to downregulation of ets1 mRNA and protein as assessed by quantitative reverse transcription PCR and western blot analysis. Furthermore, overexpression of miR-1 and miR-499 inhibited the invasion and migration of HepG2 cells in matrigel invasion and transwell migration assays, respectively. These results suggest that miR-1 and miR-499 may play an important role in the pathogenesis of HCC by regulating ets1.

SOX2-RNAi attenuates S-phase entry and induces RhoA-dependent switch to protease-independent amoeboid migration in human glioma cells

BACKGROUND

SOX2, a high mobility group (HMG)-box containing transcription factor, is a key regulator during development of the nervous system and a persistent marker of neural stem cells. Recent studies suggested a role of SOX2 in tumor progression. In our previous work we detected SOX2 in glioma cells and glioblastoma specimens. Herein, we aim to explore the role of SOX2 for glioma malignancy in particular its role in cell proliferation and migration.

METHODS

Retroviral shRNA-vectors were utilized to stably knockdown SOX2 in U343-MG and U373-MG cells. The resulting phenotype was investigated by Western blot, migration/invasion assays, RhoA G-LISA, time lapse video imaging, and orthotopic xenograft experiments.

RESULTS

SOX2 depletion results in pleiotropic effects including attenuated cell proliferation caused by decreased levels of cyclinD1. Also an increased TCF/LEF-signaling and concomitant decrease in Oct4 and Nestin expression was noted. Furthermore, down-regulation of focal adhesion kinase (FAK) signaling and of downstream proteins such as HEF1/NEDD9, matrix metalloproteinases pro-MMP-1 and -2 impaired invasive proteolysis-dependent migration. Yet, cells with knockdown of SOX2 switched to a RhoA-dependent amoeboid-like migration mode which could be blocked by the ROCK inhibitor Y27632 downstream of RhoA-signaling. Orthotopic xenograft experiments revealed a higher tumorigenicity of U343-MG glioma cells transduced with shRNA targeting SOX2 which was characterized by increased dissemination of glioma cells.

CONCLUSION

Our findings suggest that SOX2 plays a role in the maintenance of a less differentiated glioma cell phenotype. In addition, the results indicate a critical role of SOX2 in adhesion and migration of malignant gliomas.

Differential activity by polymorphic variants of a remote enhancer that supports galanin expression in the hypothalamus and amygdala: implications for obesity, depression and alcoholism

The expression of the galanin gene (GAL) in the paraventricular nucleus (PVN) and in the amygdala of higher vertebrates suggests the requirement for highly conserved, but unidentified, regulatory sequences that are critical to allow the galanin gene to control alcohol and fat intake and modulate mood. We used comparative genomics to identify a highly conserved sequence that lay 42 kb 5' of the human GAL transcriptional start site that we called GAL5.1. GAL5.1 activated promoter activity in neurones of the PVN, arcuate nucleus and amygdala that also expressed the galanin peptide. Analysis in neuroblastoma cells demonstrated that GAL5.1 acted as an enhancer of promoter activity after PKC activation. GAL5.1 contained two polymorphisms; rs2513280(C/G) and rs2513281(A/G), that occurred in two allelic combinations (GG or CA) where the dominant GG alelle occurred in 70-83 % of the human population. Intriguingly, both SNPs were found to be in LD (R(2) of 0.687) with another SNP (rs2156464) previously associated with major depressive disorder (MDD). Recreation of these alleles in reporter constructs and subsequent magnetofection into primary rat hypothalamic neurones showed that the CA allele was 40 % less active than the GG allele. This is consistent with the hypothesis that the weaker allele may affect food and alcohol preference. The linkage of the SNPs analysed in this study with a SNP previously associated with MDD together with the functioning of GAL5.1 as a PVN and amygdala specific enhancer represent a significant advance in our ability to understand alcoholism, obesity and major depressive disorder.

A matrix metalloprotease-PAR1 system regulates vascular integrity, systemic inflammation and death in sepsis

Sepsis is a deadly disease characterized by the inability to regulate the inflammatory–coagulation response in which the endothelium plays a key role. The cause of this perturbation remains poorly understood and has hampered the development of effective therapeutics. Matrix metalloproteases (MMPs) are involved in the host response to pathogens, but can also cause uncontrolled tissue damage and contribute to mortality. We found that human sepsis patients had markedly elevated plasma proMMP-1 and active MMP-1 levels, which correlated with death at 7 and 28 days after diagnosis. Likewise, septic mice had increased plasma levels of the MMP-1 ortholog, MMP-1a. We identified mouse MMP-1a as an agonist of protease-activated receptor-1 (PAR1) on endothelial cells. MMP-1a was released from endothelial cells in septic mice. Blockade of MMP-1 activity suppressed endothelial barrier disruption, disseminated intravascular coagulation (DIC), lung vascular permeability as well as the cytokine storm and improved survival, which was lost in PAR1-deficient mice. Infusion of human MMP-1 increased lung vascular permeability in normal wild-type mice but not in PAR1-deficient mice. These findings implicate MMP-1 as an important activator of PAR1 in sepsis and suggest that therapeutics that target MMP1-PAR1 may prove beneficial in the treatment of sepsis.

Regulation of angiogenesis by ETS transcription factors

Transcription factors of the ETS family are important regulators of endothelial gene expression. Here, we review the evidence that ETS factors regulate angiogenesis and briefly discuss the target genes and pathways involved. Finally, we discuss novel evidence that shows how these transcription factors act in a combinatorial fashion with others, through composite sites that may be crucial in determining endothelial specificity in gene transcription.

Modulation of enzymatic activities by n-3 polyunsaturated fatty acids to support cardiovascular health

Epidemiological evidence from Greenland Eskimos and Japanese fishing villages suggests that eating fish oil and marine animals can prevent coronary heart disease. Dietary studies from various laboratories have similarly indicated that regular fish oil intake affects several humoral and cellular factors involved in atherogenesis and may prevent atherosclerosis, arrhythmia, thrombosis, cardiac hypertrophy and sudden cardiac death. The beneficial effects of fish oil are attributed to their n-3 polyunsaturated fatty acid (PUFA; also known as omega-3 fatty acids) content, particularly eicosapentaenoic acid (EPA; 20:5, n-3) and docosahexaenoic acid (DHA; 22:6, n-3). Dietary supplementation of DHA and EPA influences the fatty acid composition of plasma phospholipids that, in turn, may affect cardiac cell functions in vivo. Recent studies have demonstrated that long-chain omega-3 fatty acids may exert beneficial effects by affecting a wide variety of cellular signaling mechanisms. Pathways involved in calcium homeostasis in the heart may be of particular importance. L-type calcium channels, the Na+-Ca2+ exchanger and mobilization of calcium from intracellular stores are the most obvious key signaling pathways affecting the cardiovascular system; however, recent studies now suggest that other signaling pathways involving activation of phospholipases, synthesis of eicosanoids, regulation of receptor-associated enzymes and protein kinases also play very important roles in mediating n-3 PUFA effects on cardiovascular health. This review is therefore focused on the molecular targets and signaling pathways that are regulated by n-3 PUFAs in relation to their cardioprotective effects.

PKC isozymes in chronic cardiac disease: possible therapeutic targets?

Cardiovascular disease is the leading cause of death in the United States. Therefore, identifying therapeutic targets is a major focus of current research. Protein kinase C (PKC), a family of serine/threonine kinases, has been identified as playing a role in many of the pathologies of heart disease. However, the lack of specific PKC regulators and the ubiquitous expression and normal physiological functions of the 11 PKC isozymes has made drug development a challenge. Here we discuss the validity of therapeutically targeting PKC, an intracellular signaling enzyme. We describe PKC structure, function, and distribution in the healthy and diseased heart, as well as the development of rationally designed isozyme-selective regulators of PKC functions. The review focuses on the roles of specific PKC isozymes in atherosclerosis, fibrosis, and cardiac hypertrophy, and examines principles of pharmacology as they pertain to regulators of signaling cascades associated with these diseases.

Myocardial Matrix Remodeling and the Matrix Metalloproteinases: Influence on Cardiac Form and Function

It is now becoming apparent that dynamic changes occur within the interstitium that directly contribute to adverse myocardial remodeling following myocardial infarction (MI), with hypertensive heart disease and with intrinsic myocardial disease such as cardiomyopathy. Furthermore, a family of matrix proteases, the matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs), has been recognized to play an important role in matrix remodeling in these cardiac disease states. The purpose of this review is fivefold: 1) to examine and redefine the myocardial matrix as a critical and dynamic entity with respect to the remodeling process encountered with MI, hypertension, or cardiomyopathic disease; 2) present the remarkable progress that has been made with respect to MMP/TIMP biology and how it relates to myocardial matrix remodeling; 3) to evaluate critical translational/clinical studies that have provided a cause-effect relationship between alterations in MMP/TIMP regulation and myocardial matrix remodeling; 4) to provide a critical review and analysis of current diagnostic, prognostic, and pharmacological approaches that utilized our basic understanding of MMP/TIMPs in the context of cardiac disease; and 5) most importantly, to dispel the historical belief that the myocardial matrix is a passive structure and supplant this belief that the regulation of matrix protease pathways such as the MMPs and TIMPs will likely yield a new avenue of diagnostic and therapeutic strategies for myocardial remodeling and the progression to heart failure.

PKCepsilon increases endothelin converting enzyme activity and reduces amyloid plaque pathology in transgenic mice

Deposition of plaques containing amyloid beta (Abeta) peptides is a neuropathological hallmark of Alzheimer's disease (AD). Here we demonstrate that neuronal overexpression of the epsilon isozyme of PKC decreases Abeta levels, plaque burden, and plaque-associated neuritic dystrophy and reactive astrocytosis in transgenic mice expressing familial AD-mutant forms of the human amyloid precursor protein (APP). Compared with APP singly transgenic mice, APP/PKCepsilon doubly transgenic mice had decreased Abeta levels but showed no evidence for altered cleavage of APP. Instead, PKCepsilon overexpression selectively increased the activity of endothelin-converting enzyme, which degrades Abeta. The activities of other Abeta-degrading enzymes, insulin degrading enzyme and neprilysin, were unchanged. These results indicate that increased neuronal PKCepsilon activity can promote Abeta clearance and reduce AD neuropathology through increased endothelin-converting enzyme activity.

The induction of CCN2 by TGFbeta1 involves Ets-1

CCN2 is encoded by an immediate-early gene induced in mesenchymal cells during the formation of blood vessels, bone and connective tissue. It plays key roles in cell adhesion and migration, as well as matrix remodeling. CCN2 is overexpressed in fibrosis, arthritis and cancer; thus, an understanding of how to control CCN2 expression is likely to have importance in developing therapies to combat these pathologies. Previously, we found that the promoter sequence GAGGAATG is important for Ccn2 gene regulation in NIH 3T3 fibroblasts. In this report, we show that this sequence mediates activation of the CCN2 promoter by the ETS family of transcription factors. Endogenous Ets-1 binds this element of the CCN2 promoter, and dominant negative Ets-1 and specific Ets-1 small interfering RNA block induction of CCN2 expression by TGFbeta. In the absence of added TGFbeta1, Ets-1, but not the related fli-1, synergizes with Smad 3 to activate the CCN2 promoter. Whereas the ability of transfected Ets-1 to activate the CCN2 promoter is dependent on protein kinase C (PKC), Ets-1 in the presence of co-transfected Smad3 does not require PKC, suggesting that the presence of Smad3 bypasses the requirement of Ets-1 for PKC to activate target promoter activity. Our results are consistent with the notion that Smad3 and Ets-1 cooperate in the induction of the CCN2 promoter by TGFbeta1. Antagonizing Ets-1 might be of benefit in attenuating CCN2 expression in fibrosis, arthritis and cancer, and may be useful in modulating the outcome of these disorders.

Docosahexaenoic acid inhibits protein kinase C translocation/activation and cardiac hypertrophy in rat cardiomyocytes

Phenylephrine (PE) induces cardiac hypertrophy through multiple signaling pathways including pathways involving protein kinase C (PKC) activation. Docosahexaenoic acid (DHA), an omega-3 fatty acid, has been shown to reduce the PE-induced hypertrophic responses. However, the effects of DHA on PKC activation and translocation are controversial. The present study investigates the effect of DHA on PE-induced activation of PKC. The results indicate that PE induces PKCalpha translocation (from cytosol to plasma membranes) and activation in cardiomyocytes during the hypertrophic responses. Although DHA itself has no significant effect on basal PKC translocation and activation, it effectively reduced PE-stimulated PKC translocation and activation. The results of the present study suggest a possible mechanism explaining how dietary fish oil may inhibit development of cardiac hypertrophy and therefore may be an attractive dietary agent for preventing cardiac hypertrophy in patients with heart failure.

Bone microenvironment modulates expression and activity of cathepsin B in prostate cancer

Prostate cancers metastasize to bone leading to osteolysis. Here we assessed proteolysis of DQ-collagen I (a bone matrix protein) and, for comparison, DQ-collagen IV, by living human prostate carcinoma cells in vitro. Both collagens were degraded, and this degradation was reduced by inhibitors of matrix metallo, serine, and cysteine proteases. Because secretion of the cysteine protease cathepsin B is increased in human breast fibroblasts grown on collagen I gels, we analyzed cathepsin B levels and secretion in prostate cells grown on collagen I gels. Levels and secretion were increased only in DU145 cells--cells that expressed the highest baseline levels of cathepsin B. Secretion of cathepsin B was also elevated in DU145 cells grown in vitro on human bone fragments. We further investigated the effect of the bone microenvironment on cathepsin B expression and activity in vivo in a SCID-human model of prostate bone metastasis. High levels of cathepsin B protein and activity were found in DU145, PC3, and LNCaP bone tumors, although the PC3 and LNCaP cells had exhibited low cathepsin B expression in vitro. Our results suggest that tumor-stromal interactions in the context of the bone microenvironment can modulate the expression of the cysteine protease cathepsin B.

Matrix metalloproteinase-1 associates with intracellular organelles and confers resistance to lamin A/C degradation during apoptosis

Since the first description of matrix metalloproteinase (MMP)-1 as an interstitial collagenase, great importance has been ascribed to this enzyme in extracellular matrix remodeling during tumoral, inflammatory, and angiogenic processes. As more evidence for the role of MMPs in targeting nonmatrix substrates emerges, casual observations that intracellular MMP-1 is found in vitro and in vivo prompt investigation of the role that MMP-1 may play on basic cell functions such as cell division and apoptosis. Here we show for the first time that MMP-1 not only has extracellular functions but that it is strongly associated with mitochondria and nuclei and accumulates within the cells during the mitotic phase of the cell cycle. On induction of apoptosis, MMP-1 co-localized with aggregated mitochondria and accumulated around fragmented nuclei. Inhibition of this enzyme by RNA interference or treatment with a broad MMP inhibitor caused faster degradation of lamin A, activation of caspases, and fragmentation of DNA when compared with untreated cells. These observations strongly suggest that intracellular association of MMP-1 to mitochondria and nuclei confers resistance to apoptosis and may explain the well-known association of this enzyme with tumor cell survival and spreading.

Ets-1 transcription factor is widely expressed in benign and malignant melanocytes and its expression has no significant association with prognosis

Ets-1 transcription factor has been associated with tumor progression in various carcinomas, but its expression in malignant melanoma was only recently described. The study was conducted in two steps: exploratory and confirmatory. In the first step, we studied 69 primary melanomas, 28 metastatic melanomas, 10 usual intradermal nevi and 13 various melanocytic skin lesions. In the second step, an additional group of 98 patients with follow-up of up to 200 months was also evaluated. Immunohistochemical analysis of formalin-fixed/paraffin-embedded tissues was performed using 1G11 antibody and polymer conjugate for visualization. While Ets-1 was variably expressed in 83% primary melanomas in exploratory and 69% in the confirmatory group, the expression of Ets-1 was also found in normal benign melanocytes and all nevi. Analysis of the exploratory group revealed lower expression of Ets-1 in primary melanomas than in common nevi (P=0.048, Mann-Whitney U-test) and metastatic melanomas expressed significantly less Ets-1 than primary melanomas (P=0.015, Mann-Whitney U-test). There was a negative correlation between Ets-1 expression and the largest dimension of the primary tumors (r=0.23, P=0.034, Spearman's correlation rank test), but no correlation with the depth of tumor invasion (Breslow thickness) or the presence of ulceration was found. Analyses of the confirmatory group revealed no association between Ets-1 expression with disease-specific survival or time to treatment failure. However, a statistical trend was found for worse outcome for those primary melanomas that had strong expression (H-score >100) of Ets-1 (P=0.054). Ets-1 is expressed in benign melanocytes probably due to their neural crest origin. We conclude that Ets-1 expression cannot be used to differentiate between benign and malignant melanocytic lesions and it has no definite association with clinical outcome. At the same time, its role in tumor progression in some cases of malignant melanoma cannot be entirely excluded.

Ets-1 immunohistochemical expression in non-melanoma skin carcinoma

BACKGROUND

Ets-1 oncoprotein is a transcription factor known to regulate the expression of numerous genes important in extracellular matrix remodeling and angiogenesis. Up-regulation of Ets-1 has been shown to be important in a variety of human malignancies and to correlate with prognosis. To our knowledge, this oncoprotein has not been examined in non-melanoma skin carcinomas.

DESIGN

A series of 26 primary cutaneous skin lesions with patient records were independently examined for diagnosis confirmation and immunohistochemical expression by two dermatopathologists. The immunohistochemical expression for Ets-1 (Novocastra, Newcastle Upon Tyne, England, UK) was scored by an average of the mean labeling intensity (MLI), where no nuclear staining = 0, weak nuclear staining = 1, moderate nuclear staining = 2, and strong nuclear staining = 3.

RESULTS

All basal cell carcinoma (BCC) and Merkel cell carcinoma (MCC) cases exhibited negative nuclear staining, for an average MLI of 0. Keratoacanthomas, squamous cell carcinoma in situ (SIS), and well-differentiated squamous cell carcinomas (SCCs) exhibited negative to weak nuclear staining, for an average MLI of 0.4 +/- 0.3. Moderately differentiated SCCs exhibited moderate nuclear staining, for an average MLI of 1.8 +/- 0.6. Poorly differentiated SCCs and metastatic SCCs exhibited very strong nuclear staining, with an average MLI of 2.8 +/- 0.2.

CONCLUSIONS

Ets-1 is not expressed in cutaneous BCC or MCC and is weakly expressed in SIS and forms of well-differentiated SCC. Although the intensity of Ets-1 immunostaining distinguished between well-differentiated and poorly differentiated SCC (p < 0.0001), it failed to discriminate between in situ and well-differentiated SCCs. The preliminary data suggests Ets-1 may be important in the pathogenesis of invasive SCC.

Induction of Endothelial Cell Activation by a Triple Helical α2β1 Integrin Ligand, Derived from Type I Collagen α1(I)496–507

Endothelial cell activation involves the elevated expression of cell adhesion molecules, chemoattractants, chemokines, and cytokines. These expression profiles may be regulated by integrin-mediated cell signaling pathways. In the current study, an alpha2beta1 integrin triple helical peptide ligand derived from type I collagen residues alpha1(I)496-507 was examined for induction of human aortic endothelial cell (HAEC) activation. In addition, a "miniextracellular matrix" composed of a mixture of the alpha1(I)496-507 ligand and a second, alpha-helical ligand incorporating the endothelial cell proliferating region of SPARC (secreted protein acidic and rich in cysteine) was studied for induction of HAEC activation. Following HAEC adhesion to alpha1(I)496-507, mRNA expression of E-selectin-1, vascular and intercellular cell adhesion molecules-1, and monocytic chemoattractant protein-1 was stimulated, whereas that of endothelin-1 was inhibited. Enzyme-linked immunosorbent assay analysis demonstrated that E-selectin-1 and monocytic chemoattractant protein-1 expression was also stimulated, whereas endothelin-1 protein expression diminished. Engagement of the alpha2beta1 integrin initiated a HAEC response similar to that of tumor necrosis factor-alpha-induced HAECs but was not sufficient to induce an inflammatory response. Addition of the SPARC119-122 region had only a slight effect on HAEC activation. Other cell-extracellular matrix interactions appear to be required to elicit an inflammatory response. The alpha2beta1 integrin specific triple helical peptide ligand described herein represents a more general in vitro model system by which gene expression and protein production profiles induced by binding to a single cellular receptor type can be quantified.

Stromal expression of invasion-promoting, matrix-degrading proteases MMP-1 and -9 and the Ets 1 transcription factor in HNPCC carcinomas and sporadic colorectal cancers

Hereditary nonpolyposis colorectal cancers (HNPCCs) are an important subgroup of colorectal carcinomas. Compared to sporadic variants, they present several particular features, the most important of which are less invasive and metastatic properties linked to a more favorable prognosis. This contrasts to the generally poor differentiation of the epithelial tumor component. Since matrix-degrading proteases secreted by stromal fibroblasts contribute significantly to tumor invasion, we analyzed the stromal expression of 2 matrix metalloproteinases (MMP-1 and -9) and of one of their regulators, the Ets 1 transcription factor, by both immunohistochemistry and in situ hybridization in sporadic colorectal carcinomas and HNPCC tumors. We found that MMP-1 and -9 as well as Ets 1 are upregulated in the fibroblastic stroma during the development from sporadic adenomas to invasive carcinomas. HNPCC tumors exhibited a significantly lower expression of Ets 1, MMP-1 and -9. These findings on the basis of lower matrix-degrading properties of the fibroblastic tumor stroma in HNPCC tumors might help to explain why, in spite of their less differentiated phenotype, HNPCC tumors have a less invasive and metastatic potential compared to sporadic cancers.

The biology of the Ets1 proto-oncogene

The Ets1 proto-oncoprotein is a member of the Ets family of transcription factors that share a unique DNA binding domain, the Ets domain. The DNA binding activity of Ets1 is controlled by kinases and transcription factors. Some transcription factors, such as AML-1, regulate Ets1 by targeting its autoinhibitory module. Others, such as Pax-5, alter Ets1 DNA binding properties. Ets1 harbors two phosphorylation sites, threonine-38 and an array of serines within the exon VII domain. Phosphorylation of threonine-38 by ERK1/2 activates Ets1, whereas phosphorylation of the exon VII domain by CaMKII or MLCK inhibits Ets1 DNA binding activity. Ets1 is expressed by numerous cell types. In haemotopoietic cells, it contributes to the regulation of cellular differentiation. In a variety of other cells, including endothelial cells, vascular smooth muscle cells and epithelial cancer cells, Ets1 promotes invasive behavior. Regulation of MMP1, MMP3, MMP9 and uPA as well as of VEGF and VEGF receptor gene expression has been ascribed to Ets1. In tumors, Ets1 expression is indicative of poorer prognosis.

Expression of the ets-1 proto-oncogene in melanocytic lesions

Ets-1 oncoprotein is a transcription factor known to regulate the expression of numerous genes important in extracellular matrix remodeling and angiogenesis. Up-regulation of Ets-1 has been shown to be important in a variety of human malignancies and to correlate with prognosis. To our knowledge, this oncoprotein has not been examined in melanocytic lesions. A series of 10 cutaneous melanomas and 24 benign melanocytic lesions with patient records were independently examined for diagnosis confirmation and immunohistochemical expression by two dermatopathologists. The immunohistochemical expression for Ets-1 (Novocastra, Newcastle upon Tyne, UK) was scored by an average of the mean labeling intensity; no nuclear staining = 0, weak nuclear staining = 1, moderate = 2, and intense = 3. Ets-1 expression was statistically assessed by the one-way analysis of variance (ANOVA) comparing the mean labeling intensity of melanoma to benign melanocytic nevi. All of the benign melanocytic lesions exhibited negative to weak nuclear staining, with an average mean labeling intensity of 0.4. Melanoma in situ exhibited moderate nuclear staining, for a mean labeling intensity of 2.0, whereas all conventional invasive melanomas exhibited moderate to strong nuclear staining, with a mean labeling intensity of 2.7. Metastatic melanoma exhibited very strong nuclear staining, with a mean labeling intensity of 3.0. Invasive desmoplastic melanoma, like melanoma in situ, showed moderate nuclear staining with a mean labeling intensity of 2.1. There was a trend toward more intense staining with melanoma progression. A statistically significant difference in the mean labeling intensity of Ets-1 was seen between invasive melanoma and benign melanocytic nevi (P <.0001). Ets-1 oncoprotein expression, however, does not distinguish among benign melanocytic lesions. Staining intensity and pattern might be a useful adjunct with histomorphology in distinguishing invasive melanoma from benign melanocytic nevi. Furthermore, Ets-1 expression may be an important pathogenic mechanism and predictor of aggressive biologic behavior of cutaneous melanoma, with a trend toward staining intensity increasing as Clark stage increases.

PTHrP [67-86] regulates the expression of stress proteins in breast cancer cells inducing modifications in urokinase-plasminogen activator and MMP-1 expression

It was previously reported that a midregion domain of parathyroid hormone-related protein (PTHrP), that is, [67-86]-amide, is able to restrain growth and promote matrigel penetration by the 8701-BC cell line, derived from a biopsy fragment of a primary ductal infiltrating carcinoma of the human breast, and that cell invasion in vitro is drastically impaired by inactivation of urokinase-plasminogen activator (uPa). In this study we started a more detailed investigation of the possible effects on gene expression arising from the interaction between PTHrP [67-86]-amide and 8701-BC breast cancer cells by a combination of conventional-, differential display-and semi-quantitative multiplex-polymerase chain reaction (PCR) assays. We present here the first evidence that the upregulation of some stress-related genes, most noticeably heat shock factor binding protein-1 (hsbp1) and heat shock protein 90 (hsp-90), is involved in the acquisition of an in vitro more invasive phenotype by cells treated with midregion PTHrP. This is conceivably accomplished by sequestering and inactivating heat shock factor-1 (hsf1) which is able to recognize Ets transcription-factor-binding sites present in some gene promoters, such as those of uPa and matrix metalloprotease-1 (MMP-1). In fact, our data show that incubation of PTHrP [67-86]-amide-treated cells with either antisense hsbp1-oligonucleotide or geldanamycin, an hsp90-inactivating antibiotic, results in downregulation of uPa and upregulation of MMP-1, and in a prominent inhibition of cell invasion in matrigel-containing Transwell chambers. Alternatively, incubation of untreated 8701-BC cells with quercetin, a flavonoid known to decrease the amount of free hsf1, is found to induce upregulation of uPa and downregulation of MMP-1, and an increase of matrigel invasion by cells, thus providing further supporting data of the involvement of hsf unavailability on the modulation of uPa and MMP-1 expression and on cell invasive behaviour. These studies confirm a previous postulate that over-secretion of uPa, rather than of other extracellular proteases, is a primary condition for the increase of invasive activity triggered by PTHrP [67-86]-amide in vitro, and support a role for midregion forms of PTHrP in potentially affecting pathological mammary growth and differentiation. They also identify two new key protagonists in the complex scenario of breast tumor cell invasiveness in vitro, that is, hsbp1 and hsp90, which deserve further and more extensive studies as potential and attractive molecular targets for anti-breast cancer treatments.

Molecular regulation of human cathepsin B: implication in pathologies

Cathepsin B is a papain-family cysteine protease that is normally located in lysosomes, where it is involved in the turnover of proteins and plays various roles in maintaining the normal metabolism of cells. This protease has been implicated in pathological conditions, e.g., tumor progression and arthritis. In disease conditions, increases in the expression of cathepsin B occur at both the gene and protein levels. At the gene level, the altered expression results from gene amplification, elevated transcription, use of alternative promoters and alternative splicing. These molecular changes lead to increased cathepsin B protein levels and in turn redistribution, secretion and increased activity. Here we focus on the molecular regulation of cathepsin B and attendant implications for tumor progression and arthritis. The potential of cathepsin B as a therapeutic target is also discussed.