Ets-1 and integrin beta3 for lung metastasis from colorectal cancer

ETS-1: A potential target of glycolysis for metabolic therapy by regulating glucose metabolism in pancreatic cancer

Pancreatic cancer is one of the most lethal malignancies of all types of cancer due to lack of early symptoms and its resistance to conventional therapy. In our previous study, we have shown that v‑ets erythroblastosis virus E26 oncogene homolog‑1 (ETS‑1) promote cell migration and invasion in pancreatic cancer cells. However, the function of ETS‑1 in regulation of glycolysis and autophagy during progression of pancreatic cancer has not been defined yet. In this study, we sought to identify the potential role for silencing ETS‑1 in reducing the expression of glucose transporter‑1 (GLUT‑1) to disturb glycolysis through alteration of 'Warburg effect', by which could result in AMP‑activated protein kinase (AMPK) activation, autophagy induction and reduction of cell viability. MTT assay was applied to assess the cell viability in ETS‑1 silencing cells and control groups. Glucose absorption rate, lactate production rate and cellular ATP level were measured by standard colorimetric assay kits. The levels of mRNAs of ETS‑1, GLUT‑1, autophagy‑related gene 5 (ATG5) and ATG7 were analyzed by qRT‑PCR. The expression of ETS‑1, GLUT‑1, ATG5, ATG7, p‑AMPK, and LC3II proteins were evaluated by western blot analysis. GraphPad Prism 5.0 was used for all statistical analysis. We found that cell viability was obviously attenuated after silencing ETS‑1. Besides, our results also showed that the expression of GLUT‑1 significantly declined in ETS‑1 silencing cell lines which resulted in a lower glucose utilization and lactate production. Furthermore, the inhibition of glycolysis, which depends on glucose utilization and lactate production, reduced the generation of energy in the form of ATP. Moreover, the reduction of cellular ATP was associated with stimulation of AMP‑activated protein kinase (AMPK) and induction of autophagy. Our results indicated that ETS‑1 induced autophagy after inhibition of glycolysis, and thus led to comparative decrease of cell viability. These results implied that ETS‑1 could be a potential target for tumor metabolic therapy.

Downregulation of β3 integrin by miR-30a-5p modulates cell adhesion and invasion by interrupting Erk/Ets‑1 network in triple-negative breast cancer

Integrins are adhesion receptors involved in bidirectional signaling and are crucial for various cellular responses during normal homeostasis and pathological conditions, such as cancer progression and metastasis. In the present study, we demonstrated that blockage of β3 integrin-mediated cell- extracellular matrix interactions restrained triple-negative breast cancer (TNBC) growth, and elevated β3 integrin can trigger the rewiring of Erk/Ets-1 signaling pathways, thereby enhancing cell growth and invasion. Ectopic expression of miRNA has been implicated in the deregulation of integrin expression and activity, blocking of cancer tumor development and progression, and acquisition of metastatic phenotype. miR-30a-5p expression has been implicated in the progression of breast cancer. Overexpression of miR-30a-5p suppressed the proliferation, migration and invasion of breast cancer cells. On the contrary, inhibition of miR-30a-5p promoted the proliferation, migration, and invasion of TNBC cells by suppressing the expression of ERK/Ets-1 signal. An inverse correlation was found between the mRNA expressions of miR-30a-5p and β3 integrin in TNBC samples. Furthermore, bioinformatics analysis revealed the putative miR-30 binding sites in the 3'-UTR of β3 integrin. Results of luciferase assay revealed a strong repression of luciferase activity after transfection with miR‑30a-5p and wild-type 3'-UTR of β3 integrin. In TNBC cells, miR-30a-5p promoted an epithelial phenotype and suppressed invasion by specifically targeting β3 integrin subunit to subsequently interdict the β3 integrin/Erk/Ets-1 network.

The role of the transcription factor Ets1 in carcinoma

Ets1 belongs to the large family of the ETS domain family of transcription factors and is involved in cancer progression. In most carcinomas, Ets1 expression is linked to poor survival. In breast cancer, Ets1 is primarily expressed in the triple-negative subtype, which is associated with unfavorable prognosis. Ets1 contributes to the acquisition of cancer cell invasiveness, to EMT (epithelial-to-mesenchymal transition), to the development of drug resistance and neo-angiogenesis. The aim of this review is to summarize the current knowledge on the functions of Ets1 in carcinoma progression and on the mechanisms that regulate Ets1 activity in cancer.

Stromal expression of heat-shock protein 27 is associated with worse clinical outcome in patients with colorectal cancer lung metastases

Background

Pulmonary metastases are common in patients with primary colorectal cancer (CRC). Heat-shock protein 27 (Hsp27) is upregulated in activated fibroblasts during wound healing and systemically elevated in various diseases. Cancer-associated fibroblasts (CAFs) are also thought to play a role as prognostic and predictive markers in various malignancies including CRC. Surprisingly, the expression of Hsp27 has never been assessed in CAFs. Therefore we aimed to investigate the expression level of Hsp27 in CAFs and its clinical implications in patients with CRC lung metastases.

Methods

FFPE tissue samples from 51 pulmonary metastases (PMs) and 33 paired primary tumors were evaluated for alpha-SMA, CD31, Hsp27 and vimentin expression by immunohistochemistry and correlated with clinicopathological variables. 25 liver metastases served as control group. Moreover, serum samples (n=10) before and after pulmonary metastasectomy were assessed for circulating phospho-Hsp27 and total Hsp27 by ELISA.

Results

Stromal expression of Hsp27 was observed in all PM and showed strong correlation with alpha-SMA (P<0.001) and vimentin (P<0.001). Strong stromal Hsp27 was associated with higher microvessel density in primary CRC and PM. Moreover, high stromal Hsp27 and αSMA expression were associated with decreased recurrence-free survival after pulmonary metastasectomy (P=0.018 and P=0.008, respectively) and overall survival (P=0.031 and P=0.017, respectively). Serum levels of phospho- and total Hsp27 dropped after metastasectomy to levels comparable to healthy controls.

Conclusions

Herein we describe for the first time that Hsp27 is highly expressed in tumor stroma of CRC. Stromal α-SMA and Hsp27 expressions correlate with the clinical outcome after pulmonary metastasectomy. Moreover, serum Hsp27 might pose a future marker for metastatic disease in CRC.

Regulation of integrin αV subunit expression by sulfatide in hepatocellular carcinoma cells

Integrin is important in migration and metastasis of tumor cells. Changes of integrin expression and distribution will cause an alteration of cellular adhesion and migration behaviors. In this study, we investigated sulfatide regulation of the integrin αV subunit expression in hepatoma cells and observed that either exogenous or endogenous sulfatide elicited a robust upregulation of integrin αV subunit mRNA and protein expression in hepatoma cells. This regulatory effect occurred with a corresponding phosphorylation (T739) of the transcription factor Sp1. Based on the electrophoretic mobility shift assay, sulfatide enhanced the integrin αV promoter activity and strengthened the Sp1 complex super-shift. The results of chromatin immunoprecipitation analysis also indicated that sulfatide enhanced Sp1 binding to the integrin αV promoter in vivo. Silence of Sp1 diminished the stimulation of integrin αV expression by sulfatide. In the early stage of sulfatide stimulation, phosphorylation of Erk as well as c-Src was noted, and inhibition of Erk activation with either U0126 or PD98059 significantly suppressed Sp1 phosphorylation and integrin αV expression. We demonstrated that sulfatide regulated integrin αV expression and cell adhesion, which was associated with Erk activation.

Transcriptional repression of Mad-Max complex by human umbilical cord blood stem cells downregulates extracellular signal-regulated kinase in glioblastoma

Previously, we have shown that human umbilical cord blood stem cell (hUCBSC) treatment downregulate cyclin D1 in glioma cells. To study the cell cycle progression and investigate the upstream molecules regulating cyclin D1 expression, we analyzed the involvement of extracellular signal-regulated kinase (ERK) and its functionality after treatment with hUCBSC. We observed downregulation of pERK after hUCBSC treatment at both transcriptional and translational levels. Increased translocation of ERK from cytoplasm to the nucleus was observed in glioma cells, whereas hUCBSC cocultures with glioma cells showed suppressed nuclear translocation. This finding suggests that hUCBSC regulates ERK by suppressing its phosphorylation at phospho-Thr(202)/Tyr(204) retarding pERK nuclear translocation. ERK promoter analysis has shown c-Myc binding sites, indicative of possible transcriptional interactions that regulate cyclin D1 and ERK expression levels. Treatment of U251 and 5310 glioma cells with U0126, a MEK/ERK inhibitor receded pERK and c-Myc levels. In another experiment, U251 and 5310 cells treated with 10074-G5, c-Myc/Max inhibitor displayed reduction in pERK and c-Myc levels suggestive of a positive feedback loop between ERK/c-Myc/Max molecules. In the present study, we show that glioma cells exhibit abundant c-Myc expression and increased c-Myc/Max activity. In contrast, the glioma cells cocultured with hUCBSC demonstrated high Mad1 expression that competitively binds to Max to repress the c-Myc/Max mediated gene transcription. Our studies thus elucidate the potential role of hUCBSC in controlling glioma cell cycle progression and invasion by limiting Max binding to c-Myc, thus regulating the expression of glioma cell cycle and invasion associated molecules such as ERK, integrins via increased levels of Mad1 expression.

Down-regulation of β3-integrin inhibits bone metastasis of small cell lung cancer

Bone is one of the most frequent targets of small cell lung cancer (SCLC) metastasis, but the molecular mechanism remains unclear. β3-integrin plays an important role in invasion of various kinds of tumors. Yet, its role in bone-metastasis of SCLC is still unknown. In this study, we first examined the expression of β3-integrin in SBC-5 and SBC-3 cells by real-time PCR, western blot and immunofluorescence. We found that, compared to none bone-metastatic SBC-3 cells, β3-integrin was highly expressed in SBC-5 cells, a specific bone-metastatic SCLC cells line characterized in our previous study. We next constructed β3-integrin siRNA and transfected SBC-5 cell line, and found that β3-integrin siRNA significantly down-regulated the β3-integrin mRNA level and protein expression in SBC-5 cell line. We further found that inhibition of β3-integrin significantly reduced tumor cell proliferation and induced apoptosis. In addition, the β3-integrin down-regulated cells presented significant decrease in cell adhesion, migration and invasion activity. Our results suggest the β3-integrin has an essential effect on tumor cell proliferation and progression, and may be a potential therapeutic target for the prevention of skeletal metastases of lung cancer.

The role of β3-integrins in tumor angiogenesis: context is everything

Integrins are a family of cell-extracellular matrix adhesion molecules that play important roles in tumor angiogenesis. αvβ3-Integrin has received much attention as a potential anti-angiogenic target because it is upregulated in tumor-associated blood vessels. Agents targeting αvβ3-integrin are now showing some success in phase III clinical trails for the treatment of glioblastoma, but the exact function of this integrin in tumor angiogenesis is still relatively unknown. This review highlights some of the recent data illustrating that β3-integrins play both pro-angiogenic and anti-angiogenic roles in tumor angiogenesis depending on the context. Specifically we will discuss how the following differentially influence β3-integrin's role in tumor angiogenesis: first, cell-matrix interactions, second, β3-integrin inhibitor doses, third, cell type, and fourth, other interacting molecules.

Endothelial-Rac1 is not required for tumor angiogenesis unless alphavbeta3-integrin is absent

Endothelial cell migration is an essential aspect of tumor angiogenesis. Rac1 activity is needed for cell migration in vitro implying a requirement for this molecule in angiogenesis in vivo. However, a precise role for Rac1 in tumor angiogenesis has never been addressed. Here we show that depletion of endothelial Rac1 expression in adult mice, unexpectedly, has no effect on tumor growth or tumor angiogenesis. In addition, repression of Rac1 expression does not inhibit VEGF-mediated angiogenesis in vivo or ex vivo, nor does it affect chemotactic migratory responses to VEGF in 3-dimensions. In contrast, the requirement for Rac1 in tumor growth and angiogenesis becomes important when endothelial beta3-integrin levels are reduced or absent: the enhanced tumor growth, tumor angiogenesis and VEGF-mediated responses in beta3-null mice are all Rac1-dependent. These data indicate that in the presence of alphavbeta3-integrin Rac1 is not required for tumor angiogenesis.

Involvement of AdipoR receptor in adiponectin-induced motility and alpha2beta1 integrin upregulation in human chondrosarcoma cells

Chondrosarcoma is a type of highly malignant tumor with a capacity to invade locally and cause distant metastasis. Chondrosarcoma shows a predilection for metastasis to the lungs. Adiponectin is a protein hormone secreted predominantly by differentiated adipocytes and is involved in energy homeostasis. However, the effect of adiponectin on migration activity in human chondrosarcoma cells is mostly unknown. We found that adiponectin increased the migration and expression of alpha2beta1 integrin in human chondrosarcoma cells. The protein and messenger RNA expression of adiponectin receptor (AdipoR1 and AdipoR2) in chondrosarcoma patients and chondrosarcoma cell lines were significantly higher than the normal cartilage. Moreover, primary chondrosarcoma and chondrosarcoma cell lines (SW1353 and JJ012) were more invasive than normal chondrocytes. Adiponectin-mediated migration and integrin expression was attenuated by 5'-adenosine monophosphate-activated protein kinase (AMPK) small interfering RNA and an AMPK inhibitor (Ara A and compound C). Activation of p38 and nuclear factor-kappa B (NF-kappaB) pathways after adiponectin treatment was demonstrated, and adiponectin-induced expression of integrins and migration activity was inhibited by the specific inhibitor and mutant of p38 and NF-kappaB cascades. This study showed for the first time that adiponectin mediates the migration of human chondrosarcoma cells. One mechanism underlying adiponectin-directed migration was transcriptional upregulation of alpha2beta1 integrin and activation of AdipoR receptor, AMPK, p38 and NF-kappaB pathways.

Integrin beta3 down-regulates invasive features of ovarian cancer cells in SKOV3 cell subclones

PURPOSE

To investigate the role of integrin beta3 in invasive features of ovarian cancer SKOV3 cells, by comparing different metastatic subclones.

METHODS

In the present study, two cell subclones, termed as S1 and S21, which possessed high and low metastatic potential, respectively, were isolated and established from human ovarian cancer parental cell line SKOV3 by the limited dilution method. The expressions of integrin alphav, integrin alphavbeta3, integrin beta3, E-cadherin, FAK and ILK in the two cell subclones were compared by means of real-time RT-PCR or flow cytometry. Subsequently, S21 was transfected with siRNA for integrin beta3 and the effects of transfection were examined by methyl thiazolyl tetrazolium (MTT) assay, colony formation assay, Matrigel invasion assay and cell migration assay.

RESULTS

The expressions of integrin alphavbeta3, integrin beta3 and E-cadherin were markedly down-regulated in S1; however, there were no significant differences in the expressions of integrin alphav, FAK and ILK beta. Of note, more than 70% knockdown of integrin beta3 expression was obtained by siRNA technique. The integrin beta3-siRNA-transfected cells showed significant increases in cell proliferation, cell migration and invasive activity in contrast with the mock-transfected cells. The expressions of integrin alphavbeta3 and E-cadherin were lower in the integrin beta3-siRNA-transfected cells compared to the mock control.

CONCLUSION

Integrin beta3, like E-cadherin, may be also a suppressor gene down-regulating invasive features of ovarian cancer cells in SKOV3 cell subclones.

Stromal cell-derived factor-1 increase alphavbeta3 integrin expression and invasion in human chondrosarcoma cells

Chondrosarcoma is a type of highly malignant tumor with a potent capacity to invade locally and cause distant metastasis. Chondrosarcoma shows a predilection for metastasis to the lungs. The stromal cell-derived factor 1 (SDF-1), constitutively secreted by human lung epithelium cells, has been shown to function in a key role for recruitment of neutrophils. Here, we found that human chondrosarcoma tissues and chondrosarcoma cell lines had significant expression of CXCR4 (SDF-1 receptor), which was higher than normal cartilage and human chondrocyte. SDF-1alpha and lung epithelium cells conditioned medium (LECM) induced the invasiveness of chondrosarcoma cells. SDF-1 siRNA inhibited LECM-induced invasion of chondrosarcoma cells and SDF-1alpha also directly induced the cell surface expression of alphavbeta3 but not alpha2beta1 and alpha5beta1 integrin. Activations of ERK and NF-kappaB pathways after SDF-1 treatment was demonstrated, and SDF-1alpha-induced expression of alphavbeta3 integrin and invasion activity was inhibited by the specific inhibitor and mutant of ERK and NF-kappaB cascades. Taken together, our results indicate that lung derived-SDF-1alpha enhances the invasiveness of chondrosarcoma cells by increasing alphavbeta3 integrin expression through the CXCR4/ERK/NF-kappaB signal transduction pathway.

Ets transcription factors in intestinal morphogenesis, homeostasis and disease

Ets transcription factors comprise a large family of sequence-specific regulators of gene expression with important and diverse roles in development and disease. Most Ets family members are expressed in the developing and/or mature intestine, frequently in a compartment-specific and temporally dynamic manner. However, with the exception of the highly expressed Elf3, involved in embryonic epithelial differentiation, little is known about Ets functions in intestinal development and homeostasis. Ets factors show altered expression in colon cancer, where they regulate pathways relevant to tumor progression. Ets factors also likely act as important modifiers of non-neoplastic intestinal disease by regulating pathways relevant to tissue injury and repair. Despite a large body of published work on Ets biology, much remains to be learned about the precise functions of this large and diverse gene family in intestinal morphogenesis, homeostasis, and both neoplastic and non-neoplastic pathology.

Transforming growth factor-beta1 increases cell migration and beta1 integrin up-regulation in human lung cancer cells

Transforming growth factor-beta1 (TGF-beta1) plays a crucial role in adhesion and migration of human cancer cells. Besides, integrins are the major adhesive molecules in mammalian cells. Here we found that TGF-beta1 increased the migration and cell surface expression of beta1 integrin in human lung cancer cells (A549 cells). TGF-beta1 stimulation increased phosphorylation of p85alpha subunit of phosphatidylinositol 3-kinase (PI3K) and Ser(473) of Akt was determined. Besides, we performed that PI3K inhibitor (Ly294002) or Akt inhibitor suppressed the TGF-beta1-induced migration activities of A549 cells. Treatment of A549 cells with NF-kappaB inhibitor (PDTC) or IkappaB protease inhibitor (TPCK) also repressed TGF-beta1-induced cells migration and beta1 integrins expression. In addition, treatment of A549 cells with TGF-beta1 induced IkappaB kinase alpha/beta (IKKalpha/beta) phosphorylation, IkappaB phosphorylation, p65 Ser(536) phosphorylation, and kappaB-luciferase activity. Furthermore, the TGF-beta1-mediated increases in IKKalpha/beta, IkappaBalpha phosphorylation and p65 Ser(536) phosphorylation were inhibited by Ly294002 and Akt inhibitor. Co-transfection with p85alpha and Akt mutants also reduced the TGF-beta1-induced kappaB-luciferase activity. Taken together, our results suggest that TGF-beta1 acts through PI3K/Akt, which in turn activates IKKalpha/beta and NF-kappaB, resulting in the activations of beta1 integrins and contributing the migration of human lung cancer cells.

TGF-beta1 increases motility and alphavbeta3 integrin up-regulation via PI3K, Akt and NF-kappaB-dependent pathway in human chondrosarcoma cells

Transforming growth factor-beta1 (TGF-beta1) plays an essential role in tumor progression and metastasis. Integrins are the major adhesive molecules in mammalian cells. Here we found that TGF-beta1 increased the migration and cell surface expression of alphavbeta3 integrin in human chondrosarcoma cells (JJ012 cells). Phosphatidylinositol 3-kinase inhibitor (PI3K; Ly294002) or Akt inhibitor inhibited the TGF-beta1-induced increase the migration of chondrosarcoma cells. TGF-beta1 stimulation increased the phosphorylation of p85 subunit of PI3K, and serine 473 of Akt. In addition, treatment of JJ102 cells with NF-kappaB inhibitor (PDTC) or IkappaB protease inhibitor (TPCK) inhibited TGF-beta1-induced cells migration and integrins expression. Treatment of JJ012 cells with TGF-beta1-induced IkappaB kinase alpha/beta (IKKalpha/beta) phosphorylation, IkappaBalpha phosphorylation, p65 Ser(536) phosphorylation, and kappaB-luciferase activity. The TGF-beta1-mediated increases in IKKalpha/beta phosphorylation and p65 Ser(536) phosphorylation were inhibited by Ly294002 and Akt inhibitor. Cotransfection with p85 and Akt mutants also reduced the TGF-beta1-induced kappaB-luciferase activity. Taken together, these results suggest that the TGF-beta1 acts through PI3K/Akt, which in turn activates IKKalpha/beta and NF-kappaB, resulting in the activations of alphavbeta3 integrins and contributing the migration of chondrosarcoma cells.

Stromal cell-derived factor-1 enhances motility and integrin up-regulation through CXCR4, ERK and NF-kappaB-dependent pathway in human lung cancer cells

The chemokine stromal-derived factor-1alpha (SDF-1alpha) and its receptor, CXCR4, play a crucial role in adhesion and migration of human cancer cells. Integrins are the major adhesive molecules in mammalian cells. Here we found that SDF-1alpha increased the migration and cell surface expression of beta1 or beta3 integrin in human lung cancer cells (A549 cells). CXCR4-neutralizing antibody, CXCR4 specific inhibitor (AMD3100) or small interfering RNA against CXCR4 inhibited the SDF-1alpha-induced increase in the migration of lung cancer cells. Stimulation of cells with SDF-1alpha caused an increase in extracellular signal regulated kinase (ERK) phosphorylation in a time-dependent manner. In addition, treatment of A549 cells with ERK inhibitor (PD98059), NF-kappaB inhibitor (PDTC) or IkappaB protease inhibitor (TPCK) inhibited SDF-1alpha-induced cells migration and integrins expression. Treatment of A549 cells with SDF-1alpha induced IkappaB kinase alpha/beta (IKK alpha/beta) phosphorylation, IkappaBalpha phosphorylation, IkappaBalpha degradation, p65 Ser(536) phosphorylation, and kappaB-luciferase activity. The SDF-1alpha-mediated increases in IKK alpha/beta phosphorylation, p65 Ser(536) phosphorylation, and kappaB-luciferase activity were inhibited by PD98059 and ERK2 mutant. Taken together, these results suggest that SDF-1alpha acts through CXCR4 to activate ERK, which in turn activates IKKalpha/beta and NF-kappaB, resulting in the activations of beta1 and beta3 integrins and contributing the migration of lung cancer cell.

Increased expression of avian erythroblastosis virus E26 oncogene homolog 1 in World Health Organization grade 1 meningiomas is associated with an elevated risk of recurrence and is correlated with the expression of its target genes matrix metalloproteinase-2 and MMP-9

BACKGROUND

The transcription factor avian erythroblastosis virus E26 (V-Ets) oncogene homolog 1 (Ets-1) is involved in tumor development and progression through the transcriptional regulation of several matrix-degrading enzyme systems, including matrix metalloproteinases (MMPs). It has been demonstrated that the MMPs are expressed strongly in high-grade meningiomas. To determine the biologic significance of Ets-1 in the progression of benign meningiomas, the authors investigated the expressions of Ets-1 and its target genes MMP-2 and MMP-9 in primary and recurrent, Grade 1 meningiomas.

METHODS

The expression levels of Ets-1, MMP-2, and MMP-9 were examined by immunohistochemistry in 70 Grade 1 meningiomas, including 36 primary tumors without recurrence after 5 years of follow-up and 17 pairs of primary tumors and subsequent recurrences.

RESULTS

The results demonstrated higher expression of Ets-1, MMP-2, and MMP-9 proteins in meningiomas with subsequent recurrences compared with meningiomas from patients who had no recurrences (P < .001). In addition, Ets-1 expression was correlated with the expression of both MMP-2 and MMP-9.

CONCLUSIONS

Ets-1 may be involved in meningioma recurrence by up-regulating MMP-2 and MMP-9. Increased expression of these genes in World Health Organization grade 1 meningiomas may serve as an indicator for a high risk of recurrence.

Ets-1 is up-regulated together with its target gene products matrix metalloproteinase-2 and matrix metalloproteinase-9 in atypical and anaplastic meningiomas

AIMS

Matrix metalloproteinases (MMPs) are a pivotal enzyme system involved in extracellular matrix (ECM) degradation and are considered to be important in the development and invasion of human tumours. Little is known about the regulation of MMPs in meningioma development and prognosis. The transcription factor Ets-1 is the main regulator of several MMPs, including MMP-2 and -9. The aim of this study was to determine the relationship between the expression of Ets-1, MMP-2 and -9 and the malignant potential of meningiomas.

METHODS AND RESULTS

Seventy-four meningiomas of different histological grades were investigated immunohistochemically. Up-regulation of Ets-1, MMP-2 and MMP-9 expression was observed in atypical and anaplastic meningiomas. Invasive meningiomas showed increased immunohistochemical expression of these proteins compared with non-invasive meningiomas. We also observed a correlation between the expression of Ets-1 and of its target genes MMP-2 and MMP-9.

CONCLUSIONS

Ets-1 may be involved in the transcriptional regulation of MMP-2 and MMP-9 as well as in the invasive process in meningiomas. Evaluation of these expressions might be of prognostic value for meningiomas.

Collagen binding alpha2beta1 and alpha1beta1 integrins play contrasting roles in regulation of Ets-1 expression in human liver myofibroblasts

Activation of hepatic stellate cells from quiescence to myofibroblast-like cells (MFBs) is a pivotal event in hepatic fibrogenesis. Plastic-cultured stellate cells (an established in vitro model of the activated phenotype) recultured on Matrigel revert to quiescence. In the present study we analyzed the molecular mechanism underlying this process, focusing on the effect of collagen receptors alpha(2)beta(1) and alpha(1)beta(1) integrin signaling on the expression of Ets-1 transcription factor and its target gene MMP1 in cultured human MFBs. Cells grown in 3-dimensional (3D) substrates (Matrigel) or collagen type I gel) markedly upregulated Ets-1 and MMP1 messages, in comparison to cells cultured on plastic. A similar effect but less intense was mimicked by stimulation of alpha(2)beta(1) or blocking of alpha(1)beta(1) integrin in cells grown on plastic. We observed increased expression of MMP1 transcripts with parallel changes in MMP1 promoter activity, and in mRNA and protein levels of upstream transcription factors Ets-1 and c-Jun. Interference with alpha(2)beta(1) and alpha(1)beta(1) integrin function in cells cultured in a 3D collagen substrate resulted in an even greater effect. Morphologically, stimulation of alpha(2)beta(1) integrin resulted in formation of multicellular networks, probably by facilitation of cell migration. Thus, we report the novel observation that in cultured human MFBs reverting to quiescence, the expression of transcription factor Ets-1 and its downstream target MMP1 can be modulated by changes in the microenvironment, which are mediated, at least in part, by the balance between collagen receptor integrin alpha(2)beta(1) and alpha(1)beta(1) activities.

ETS transcription factors and their emerging roles in human cancer

Cancer can be defined as a genetic disease, resulting as a consequence of multiple events associated with initiation, promotion and metastatic growth. Cancer results from the loss of control of cellular homeostasis. Cell homeostasis is the result of the balance between proliferation and cell death, while cellular transformation can be viewed as a loss of relationship between these events. Oncogenes and tumour suppressor genes act as modulators of cell proliferation, while the balance of apoptotic and anti-apoptotic genes controls cell death. All cancer cells acquire similar sets of functional capacities: (1) independence from mitogenic/growth signals; (2) loss of sensitivity to "anti-growth" signals; (3) evade apoptosis; (4) Neo-angiogenic conversion; (5) release from senescence; and (6) invasiveness and metastasis. One of the goals of molecular biology is to elucidate the mechanisms that contribute to the development and progression of cancer. Such understanding of the molecular basis of cancer will provide new possibilities for: (1) earlier detection as well as better diagnosis and staging of disease with detection of minimal residual disease recurrences and evaluation of response to therapy; (2) prevention; and (3) novel treatment strategies. We feel that increased understanding of ETS-regulated biological pathways will directly impact these areas. ETS proteins are transcription factors that activate or repress the expression of genes that are involved in various biological processes, including cellular proliferation, differentiation, development, transformation and apoptosis. Identification of target genes that are regulated by a specific transcription factor is one of the most critical areas in understanding the molecular mechanisms that control transcription. Furthermore, identification of target gene promoters for normal and oncogenic transcription factors provides insight into the regulation of genes that are involved in control of normal cell growth, and differentiation, as well as provide information critical to understanding cancer development. This review will highlight the current understanding of ETS genes and their role in cancer.

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.

Ets gene PEA3 cooperates with beta-catenin-Lef-1 and c-Jun in regulation of osteopontin transcription

Osteopontin (OPN) is a multifunctional protein implicated in mammary development, neoplastic change, and metastasis. OPN is a target gene for beta-catenin-T cell factor signaling, which is commonly disturbed during mammary oncogenesis, but the understanding of OPN regulation is incomplete. Data base-assisted bioinformatic analysis of the OPN promoter region has revealed the presence of T cell factor-, Ets-, and AP-1-binding motifs. Here we report that beta-catenin, Lef-1, Ets transcription factors, and the AP-1 protein c-Jun each weakly enhanced luciferase expression from a OPN promoter-luciferase reporter construct, transiently transfected into a rat mammary cell line. OPN promoter responsiveness to beta-catenin and Lef-1, however, was considerably enhanced by Ets transcription factors including Ets-1, Ets-2, ERM, and particularly PEA3. PEA3 also enhanced promoter responsiveness to the AP-1 protein c-Jun. Co-transfection of cells with beta-catenin, Lef-1, PEA3, and c-Jun in combination increased luciferase expression by up to 280-fold and induced expression of endogenous rat OPN. In six human breast cell lines, those that highly expressed OPN also expressed PEA3 and Ets-1. Moreover, there was a significant association of immunocytochemical staining for OPN and one of beta-catenin, Ets-1, Ets-2, PEA3, or c-Jun, in the 29 human breast carcinomas tested. This study shows that beta-catenin/Lef-1, Ets, and AP-1 transcription factors can cooperate in a rat mammary cell line in stimulating transcription of OPN and that their independent presence is associated with that of OPN in a group of human breast cancers. These results suggest that the presence of these transcription factors in human breast cancer is responsible in part for the overexpression of OPN that, in turn, is implicated in mammary neoplastic progression and metastasis.

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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.