Overexpression of Id-1 in prostate cancer cells promotes angiogenesis through the activation of vascular endothelial growth factor (VEGF)

Xenografts on nude mouse diaphragm of human DU145 prostate carcinoma cells: mesothelium removal by outgrowths and angiogenesis

Human prostate carcinoma DU145 cells, androgen-independent malignant cells, implanted in the athymic nu/nu male mouse, developed numerous tumors on peritoneal and retro-peritoneal organs whose growth aspects and vascular supply have yet to be investigated with fine structure techniques. A series of necropsies from moribund implanted mice diaphragms were examined with light, scanning, and transmission electron microscopy. DU145 xenografts installations, far away from the implanted site, were described as the smallest installation to large diaphragm outgrowths in moribund mice. Carcinomas did not show extracellular matrix and, reaching more than 0.15 mm in thickness, they revealed new structures in these outgrowths. Voids to be gland-like structures with mediocre secretion and, unexpectedly, intercellular spaces connected with fascicles of elongated DU145 cells that merged with a vascular supply originated from either the tumor cells and/or some perimysium vessels. In the largest carcinomas, most important vascular invasions coincidently accompanied the mouse lethality, similarly to human cancers. This androgen-independent model would be useful to study tumor outgrowth's changes related to testing anticancer strategy, including anti-angiogenic therapies involving toxicity, simultaneously with those of other vital organs with combined biomolecular and fine structure techniques.

The Role and Research Progress of Inhibitor of Differentiation 1 in Atherosclerosis

Inhibitor of differentiation 1 has a helix-loop-helix (HLH) structure, belongs to a class of molecules known as the HLH trans-acting factor family, and plays an important role in advancing the cell cycle, promoting cell proliferation and inhibiting cell differentiation. Recent studies have confirmed that inhibitor of differentiation 1 plays an important role in the endothelial-mesenchymal transition of vascular endothelial cells, angiogenesis, reendothelialization after injury, and the formation and rupture of atherosclerotic plaques. An in-depth understanding of the role of inhibitor of differentiation 1 in atherosclerosis will provide new ideas and strategies for the treatment of related diseases.

The vascular endothelial growth factor signaling pathway regulates liver sinusoidal endothelial cells during liver regeneration after partial hepatectomy

INTRODUCTION

Liver regeneration after partial hepatectomy is a very complex and well-regulated procedure. It utilizes all liver cell types, which are associated with signaling pathways involving growth factors, cytokines, and stimulatory and inhibitory feedback of several growth-related signals. Liver sinusoidal endothelial cells (LSECs) contribute to liver regeneration after partial hepatectomy. Vascular endothelial growth factor (VEGF) has various functions in LSECs. In this review, we summarize the relationship between VEGF and LSECs involving VEGF regulatory activity in the vascular endothelium.

AREAS COVERED

Maintenance of the fenestrated LSEC phenotype requires two VEGF pathways: VEGF stimulated-NO acting through the cGMP pathway and VEGF independent of nitric oxide (NO). The results suggest that VEGF is a key regenerating mediator of LSECs in the partial hepatectomy model. NO-independent pathway was also essential to the maintenance of the LSEC in liver regeneration.

EXPERT OPINION

Liver regeneration remains a fascinating and significative research field in recent years. The liver involved of molecular pathways except for LSEC-VEGF pathways that make the field of liver further depth studies should be put into effect to elaborate the undetermined confusions, which will be better to understand liver regeneration.

The Role of Long Non-coding RNA Prostate Cancer-Associated Transcript 1 in Prostate Cancer

This study aimed to investigate the role of prostate cancer associated transcript 1 (PCAT1) underlying the molecular mechanisms of prostate cancer. Using GSE29886 data set downloaded from Gene Expression Omnibus database, we screened the differentially expressed genes (DEGs) in PCAT1-siRNA interfering (PCAT1-siRNA) LNCaP cells compared with control-siRNA cells. Transcription factor (TF) and tumor-associated genes database were used to obtain oncogenes and tumor suppressor genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were used to investigate the function and pathways of DEGs. Subnetwork was further analyzed using BioNet. A total of 93 DEGs were identified. KEGG analysis showed downregulated TF genes (ID1 and ID3) were enriched in transforming growth factor-β pathway, whereas upregulated genes were involved in pathways associated with immune system, environmental sensing, and metabolism. GO analysis showed that downregulated genes were primarily enriched in cell cycle-related biological functions and upregulated DEGs were related to immune response, exogenous genetic material response, and viral response. Centromere protein F (CENPF) was identified as the central node of the regulatory subnetwork. In the PCAT1 knockdown LNCaP cells, the CENPF, ID1, and ID3 were obviously decreased based on the RT-PCR (quantitative real-time reverse transcription PCR) analysis. PCAT1 may be involved in cell cycle and proliferation of prostate cancers by mediating the expression of CENPF, ID1, and ID3.

Baicalein Inhibits Orthotopic Human Non-Small Cell Lung Cancer Xenografts via Src/Id1 Pathway

Non-small cell lung cancer (NSCLC) is one of the most lethal cancers worldwide. Inhibitor of differentiation 1 (Id1) is the member mostly linked to tumorigenesis in Id family and a potential molecular target in cancer therapy. In the current study, we established an orthotopic lung cancer model by injecting athymic nude mice with A549 cells and evaluated the antitumor effect of baicalein and expression of Id1-related proteins in vivo and in vitro. Micro-CT images showed that tumor volume in baicalein group was significantly reduced. Western blot analysis revealed that baicalein suppressed the expression of Id1 protein, epithelial-to-mesenchymal transition (EMT) related molecules (N-Cadherin, vimentin), and angiogenesis related protein (VEGF-A), accompanied by upregulation of epithelial markers (such as E-cadherin). In addition, phosphorylation of upstream molecular Src was significantly restrained after baicalein treatment. This study firstly demonstrates that baicalein inhibits tumor growth in orthotopic human NSCLC xenografts via targeting Src/Id1 pathway.

BMP-2 induces angiogenesis by provoking integrin α6 expression in human endothelial progenitor cells

Bone morphogenetic protein-2 (BMP-2) is a multifunctional cytokine, capable of governing several cellular functions, including proliferation, motility, differentiation, and angiogenesis. Circulating endothelial progenitor cells (EPCs) have been shown to facilitate tissue repair, postnatal neovascularization, and tumor associated angiogenesis. Nevertheless, the impact of BMP-2 on angiogenesis of human EPCs has largely remained a mystery. In this study, we found that BMP-2 promoted cell migration and tube formation of EPCs in a concentration-dependent manner, indicating BMP-2 induced in vitro angiogenesis in human EPCs. Furthermore, BMP-2 significantly increased microvessel formation in Matrigel plug assay, and BMP-2 antagonist noggin prevented BMP-2-induced in vivo angiogenesis. Mechanistic investigations showed BMP-2 profoundly induced the expression of Id-1 and integrin α6 as well as EPCs angiogenesis by activating PI3K/Akt and MEK/ERK signaling pathways. Moreover, knockdown of Id-1 and integrin α6 by siRNA transfection obviously attenuated BMP-2-indueced tube formation of EPCs. These results suggest that BMP-2 promotes angiogenesis in human EPCs through the activation of PI3K/Akt, MEK/ERK, and Id-1/integrin α6 signaling cascades. This is the first demonstration that BMP-2 exhibits the angiogenesis property on human EPCs. BMP-2 might serve as the potential therapeutic target for treatment of angiogenesis-related diseases.

ID1 contributes to cell growth invasion and migration in salivary adenoid cystic carcinoma

Previous studies have reported that inhibitor of DNA binding 1 (ID1) exerts an oncogenic role in a number of tumors. In the present study, the role of ID1 in the growth, invasion and migration of salivary adenoid cystic carcinoma (SACC) cells was investigated. ID1 expression in clinical SACC samples was compared with that in normal salivary tissues using immunohistochemical staining, and the correlation between ID1 expression and clinical pathological characteristics was then determined. Subsequently, ID1 was overexpressed or silenced to investigate the effects of ID1 expression on SACC cell proliferation, invasion and migration. In addition, the gene expression levels of known ID1 target genes, including S100A9, CDKN2A and matrix metalloproteinase 1 (MMP1) was measured using reverse transcription-quantitative polymerase chain reaction to elucidate the potential mechanisms of ID1 in SACC. The results of the present study indicated that the protein expression levels of ID1 were significantly increased in the SACC tissues compared with that in the normal salivary tissues (P<0.001), and a positive correlation between ID1 expression and tumor stage (P=0.001), tumor invasion (P=0.002) and metastasis (P=0.019) in SACC was observed. Knockdown of ID1 in SACC cells significantly inhibited cell growth, invasion and migration (all P<0.01), whereas overexpression of ID1 promoted cell proliferation, invasion and migration (all P<0.01). The gene expression level of MMP1 was significantly reduced following ID1 knockdown in SACC-83 cells when compared with negative controls (P<0.05), whereas S100A9 and CDKN2A expression levels were significantly upregulated (both P<0.05). The results suggest that ID1 may regulate the growth, invasion and migration of SACC cells, and that MMP1, S100A9 and CDKN2A may serve as target genes of ID1 and mediate the effects of ID1 in SACC cells. Therefore, ID1 may present a potential target gene for the treatment of patients with SACC to inhibit cancer cell growth and metastasis.

CDC27 Induces Metastasis and Invasion in Colorectal Cancer via the Promotion of Epithelial-To-Mesenchymal Transition

Distant metastasis is the primary cause of cancer-related death among patients with colorectal cancer (CRC), and the discovery of novel therapeutic targets by further exploring the molecular mechanisms of CRC metastasis is therefore urgently needed. We previously illustrated that CDC27 overexpression promoted proliferation in CRC, but no studies have emphasized the role of CDC27 in cancer metastasis thus far. Our previous data indicated that the expression of CDC27 was significantly associated with distant metastasis in patient tissues, and therefore, in this study, we focused on the investigation of the potential mechanisms of CDC27 in CRC metastasis. The results revealed that CDC27 promoted the metastasis, invasion and sphere-formation capacity of DLD1 cells, but that the inhibition of CDC27 in HCT116 cells suppressed metastasis both in vitro and in vivo. Mechanistic analyses revealed that CDC27 promoted epithelial-to-mesenchymal transition (EMT), as demonstrated by the reduced expression of the epithelial markers ZO-1 and E-cadherin and the enhanced expression of the mesenchymal markers ZEB1 and Snail in HCT116 and DLD1 cells. Further mechanistic investigation indicated that CDC27 promoted metastasis and sphere-formation capacity in an ID1-dependent manner. In conclusion, we first demonstrated the role of CDC27 in cancer metastasis and showed that CDC27 may serve as a promising therapeutic target for CRC.

Secreted frizzled-related protein 1 overexpression in gastric cancer: Relationship with radiological findings of dual-energy spectral CT and PET-CT

We explored the role of secreted frizzled-related protein 1 (sFRP1) overexpression in gastric cancer and its relationship with radiological findings from dual-energy spectral CT(DEsCT) and positron emission tomography/computed tomography (PET/CT). We established mouse metastatic models using the SGC-7901/sFRP1 gastric cancer cell line. A control group was established using the SGC-7901/vector cell line. The models were then scanned with dual-energy spectral CT and PET-CT. Subsequent analysis, including immunohistochemistry and Transferase-mediated deoxyuridine triphosphate-biotin nick end labelling (TUNEL), was performed to confirm the role of sFRP1. Transwell chamber and angiogenesis assays were conducted to verify the effect of sFRP1 in vitro. We found that the control group showed negative radiological performance with successful implantation. Concurrently, the treated group showed visible lesions, a higher FDG uptake and increasing enhancement. The immunological and histological analysis confirmed the positive radiological performance with larger size, increasing proliferation, more microvessels and less apoptosis. The angiogenic up-regulation of sFRP1 overexpression were further verified with in vitro cell models. This preliminary study demonstrates that sFRP1 overexpression in gastric cancer cells leads to increased cell proliferation and angiogenesis, which may, in turn, contribute to positive PET/CT and CT performances.

Inhibitor of DNA-binding 1 promotes endothelial progenitor cell proliferation and migration by suppressing E2-2 through the helix-loop-helix domain

Vascular endothelial damage is the major contributing factor to cardiovascular diseases. Recently, the therapeutic significance of endothelial progenitor cells (EPCs) has drawn increasing attention due to their roles in re-endothelialization following injury. The inhibitor of DNA-binding 1 (ID1) has been proven to promote EPC proliferation and migration, suggesting a critical function of ID1 in re-endothelialization. However, the underlying mechanisms remain undefined. In this study, ID1 was found to interact with E2-2 using immunoprecipitation analysis. Moreover, ID1 overexpression suppressed E2-2 expression and luciferase reporter activity; however, these effects were not observed in cells transfected with ID1 lacking the helix-loop-helix (HLH) domain (ID1ΔHLH). Further functional analysis corroborated that the upregulation of E2-2 markedly attenuated the ID1-mediated increase in EPC proliferation and migration. Furthermore, the HLH domain plays an important role in ID1-induced EPC proliferation and migration, as its deletion suppressed the positive regulatory effects of ID1 on EPC proliferation and migration. Taken together, the findings of our study confirm that ID1 promotes EPC proliferation and migration by suppressing E2-2 through the HLH domain in ID1. Therefore, ID1 may represent a potential therapeutic target for EPC-mediated re-endothelialization following vascular injury.

ATF3 suppresses ESCC via downregulation of ID1

Esophageal cancer is one of the most prevalent forms of cancer and has a particularly high mortality rate due to early metastasis; however, the underlying mechanisms of its formation and progression remain unclear. The present study performed immunohistochemical analysis and observed that the expression of activating transcription factor 3 (ATF3) was reduced in esophageal squamous cell carcinoma (ESCC) in comparison with non-tumor adjacent tissues. By contrast, inhibitor of DNA binding 1 (ID1) was overexpressed in ESCC tissues, demonstrating an inverse correlation with ATF3 (P<0.01). In ESCC EC109 and KYSE450 cells lines, transfection with an ATF3-overexpression plasmid resulted in the inhibition of cell proliferation, motility and migration, which was associated with the induction of E-cadherin expression and inhibition of cyclin D1 and Twist. Notably, ATF3 exerted an inverse regulatory interaction with ID1. The results of the present study provide additional evidence of the tumor suppressive features of ATF3 and demonstrate a novel mechanism of ATF3-mediated inhibition of cancer metastasis in esophageal cancer.

Scleroderma dermal microvascular endothelial cells exhibit defective response to pro-angiogenic chemokines

OBJECTIVES

Angiogenesis plays a critical role in SSc (scleroderma). The aim of this study was to examine the expression of growth-regulated protein-γ (Gro-γ/CXCL3), granulocyte chemotactic protein 2 (GCP-2/CXCL6) and their receptor CXCR2 in endothelial cells (ECs) isolated from SSc skin and determine whether these cells mount an angiogenic response towards pro-angiogenic chemokines. The downstream signalling pathways as well as the pro-angiogenic transcription factor inhibitor of DNA-binding protein 1 (Id-1) were also examined.

METHODS

Skin biopsies were obtained from patients with dcSSc. ECs were isolated via magnetic positive selection. Angiogenesis was measured by EC chemotaxis assay.

RESULTS

Gro-γ/CXCL3 and GCP-2/CXCL6 were minimally expressed in both skin types but elevated in SSc serum. Pro-angiogenic chemokine mRNA was greater in SSc ECs than in normal ECs. SSc ECs did not migrate to vascular endothelial growth factor (VEGF), Gro-γ/CXCL3, GCP-2/CXCL6 or CXCL16. The signalling pathways stimulated by these chemokines were also dysregulated. Id-1 mRNA in SSc ECs was lower compared with normal ECs, and overexpression of Id-1 in SSc ECs increased their ability to migrate towards VEGF and CXCL16.

CONCLUSION

Our results show that SSc ECs are unable to respond to pro-angiogenic chemokines despite their increased expression in serum and ECs. This might be due to the differences in the signalling pathways activated by these chemokines in normal vs SSc ECs. In addition, the lower expression of Id-1 also decreases the angiogenic response. The inability of pro-angiogenic chemokines to promote EC migration provides an additional mechanism for the impaired angiogenesis that characterizes SSc.

Krüppel-like factor 17, a novel tumor suppressor: its low expression is involved in cancer metastasis

Krüppel-like factor (KLF) family is highly conserved zinc finger transcription factors that regulate cell proliferation, differentiation, apoptosis, and migration. KLF17 is a member of the KLF family. Recent studies have demonstrated that KLF17 low expression and inactivation are caused by microRNA, gene mutation, and loss of heterozygosity in human tumors, which participates in tumor progression. KLF17 low expression increases cancer metastatic viability; its mechanism is that low KLF17 mediates epithelial-mesenchymal transition (EMT) through regulating EMT-related genes expression; the reduced-KLF17 also increases cancer metastasis though upregulating inhibitor of DNA binding 1 (ID1). Additionally, mutant p53 proteins are capable of developing a complex with KLF17, which mediate the depletion of KLF17 inhibiting EMT gene transcription and increases cancer metastasis. KLF17 downregulation also mediates the activation of TGF-β pathway.

Peritoneal VEGF-A expression is regulated by TGF-β1 through an ID1 pathway in women with endometriosis

VEGF-A, an angiogenic factor, is increased in the peritoneal fluid of women with endometriosis. The cytokine TGF-β1 is thought to play a role in the establishment of endometriosis lesions. Inhibitor of DNA binding (ID) proteins are transcriptional targets of TGF-β1 and ID1 has been implicated in VEGF-A regulation during tumor angiogenesis. Herein, we determined whether peritoneal expression of VEGF-A is regulated by TGF-β1 through the ID1 pathway in women with endometriosis. VEGF-A was measured in peritoneal fluid by ELISA (n = 16). VEGF-A and ID1 expression was examined in peritoneal biopsies (n = 13), and primary peritoneal and immortalized mesothelial cells (MeT5A) by immunohistochemistry, qRT-PCR and ELISA. VEGF-A was increased in peritoneal fluid from women with endometriosis and levels correlated with TGF-β1 concentrations (P < 0.05). VEGF-A was immunolocalized to peritoneal mesothelium and TGF-β1 increased VEGFA mRNA (P < 0.05) and protein (P < 0.05) in mesothelial cells. ID1 was increased in peritoneum from women with endometriosis and TGF-β1 increased concentrations of ID1 mRNA (P < 0.05) in mesothelial cells. VEGF-A regulation through ID1 was confirmed by siRNA in MeT5A cells (P < 0.05). Our data supports role for ID1 in the pathophysiology of endometriosis, as an effector of TGFβ1 dependent upregulation of VEGF-A, and highlights a novel potential therapeutic target.

New Mutations of the ID1 Gene in Acute Myeloid Leukemia Patients

OBJECTIVES

Overexpression of the inhibitor of DNA binding 1 (ID1) protein is found in many types of cancer. In acute myeloid leukemia (AML), the expression of ID1 is induced by abnormal tyrosine kinases, such as FLT3 and BCR-ABL. High level expression of ID1 is associated with poor prognosis in young patients. We aimed to explore the ID1 mutation and its prognosis in AML patients.

METHODS

Two hundred and sixty-three AML patients were included. Cytogenetic results and ID1 mutation were compared. The ID1 gene was amplified by nested PCR, and the mutation was identified by direct sequencing.

RESULTS

Four new ID1 mutations (G40C, A124G, A230G, A349G) were identified in the normal karyotype patients. The A349G mutation, located in the nuclear export signal domain of the ID1 protein, was predicted by the in silico method as a damaged protein. Meanwhile, another new mutation, A290G, found in cases with 11q23 deletion, corresponded to the amino acid 97 in the helix 1 position of the ID1 protein. It could interfere with the dimerization of ID1 and EST-1, leading to a disruption of cell proliferation.

CONCLUSIONS

In this study, we found 5 mutations in 260 AML patients. ID1 mutations were not commonly observed in AML. This may differ in other hematologic malignancies. Further studies in other types of hematologic malignancy will help to clarify the importance of ID1 mutations. © 2015 S. Karger AG, Basel.

The peritoneum is both a source and target of TGF-β in women with endometriosis

Transforming growth factor-β (TGF-β) is believed to play a major role in the aetiology of peritoneal endometriosis. We aimed to determine if the peritoneum is a source of TGF-β and if peritoneal TGF-β expression, reception or target genes are altered in women with endometriosis. Peritoneal fluid, peritoneal bushings and peritoneal biopsies were collected from women with and without endometriosis. TGF-β1, 2 and 3 protein concentrations were measured in the peritoneal fluid. TGF-β1 was measured in mesothelial cell conditioned media. Control peritoneum and peritoneum prone to endometriosis (within Pouch of Douglas) from women without disease (n = 16) and peritoneum distal and adjacent to endometriosis lesions in women with endometriosis (n = 15) and were analysed for TGF-β expression, reception and signalling by immunohistochemistry, qRT-PCR and a TGF-β signalling PCR array. TGF-β1 was increased in the peritoneal fluid of women with endometriosis compared to those without disease (P<0.05) and peritoneal mesothelial cells secrete TGF-β1 in-vitro. In women with endometriosis, peritoneum from sites adjacent to endometriosis lesions expressed higher levels of TGFB1 mRNA when compared to distal sites (P<0.05). The TGF-β-stimulated Smad 2/3 signalling pathway was active in the peritoneum and there were significant increases (P<0.05) in expression of genes associated with tumorigenesis (MAPK8, CDC6), epithelial-mesenchymal transition (NOTCH1), angiogenesis (ID1, ID3) and neurogenesis (CREB1) in the peritoneum of women with endometriosis. In conclusion, the peritoneum, and in particular, the peritoneal mesothelium, is a source of TGF-β1 and this is enhanced around endometriosis lesions. The expression of TGF-β-regulated genes is altered in the peritoneum of women with endometriosis and this may promote an environment favorable to lesion formation.

Increased expression of Id1 and Id3 promotes tumorigenicity by enhancing angiogenesis and suppressing apoptosis in small cell lung cancer

Constant deregulation of Id1 and Id3 has been implicated in a wide range of carcinomas. However, underlying molecular evidence for the joint role of Id1 and Id3 in the tumorigenicity of small cell lung cancer (SCLC) is sparse. Investigating the biological significance of elevated expression in SCLC cells, we found that Id1 and Id3 co-suppression resulted in significant reduction of proliferation rate, invasiveness and anchorage-independent growth. Suppressing both Id1 and Id3 expression also greatly reduced the average size of tumors produced by transfectant cells when inoculated subcutaneously into nude mice. Further investigation revealed that suppressed expression of Id1 and Id3 was accompanied by decreased angiogenesis and increased apoptosis. Therefore, the SCLC tumorigenicity suppression effect of double knockdown of Id1 and Id3 may be regulated through pathways of apoptosis and angiogenesis.

ID2 predicts poor prognosis in breast cancer, especially in triple-negative breast cancer, and inhibits E-cadherin expression

Background

Inhibitors of DNA-binding (ID) proteins are known as important modulators in the regulation of cell proliferation and differentiation. This study sought to investigate the prognostic value of ID proteins in breast cancer.

Methods

The prognostic role of ID proteins in human breast cancer was investigated in 250 breast cancers, via tissue microarrays. The messenger (m)RNA and protein levels of E-cadherin were examined by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and Western blotting, in cells overexpressing IDs. Dual-luciferase report assay was used to investigate the potential mechanism, and a migration assay was performed to investigate the influence of IDs on cell migratory activity.

Results

The survival analysis with Kaplan–Meier and Cox regression showed that ID2 expression level, which correlated with estrogen receptor status and E-cadherin abundance, served as an independent prognostic factor for disease-free survival (DFS) (P=0.013). The prognostic value of ID2 for DFS was most significant in triple-negative breast cancer patients (P=0.009). We also found that ID2 was negatively correlated with E-cadherin expression by correlation analysis (P=0.020, Pearson’s R=−0.155). Subsequently, we explored the biological rationale and uncovered that the enforced expression of ID proteins could suppress E-cadherin expression significantly, thus increasing the migration ability of mammary epithelial cells. Then using a combination of ID2 and E-cadherin expression, the patients were classified into four subgroups with different DFS (P=0.023).

Conclusion

The overexpression of ID2 can be used as a prognostic marker in breast cancer patients, especially in triple-negative breast cancer patients. ID proteins were still, unexpectedly, revealed to inhibit E-cadherin abundance.

Inhibitor of differentiation 4 (ID4) inactivation promotes de novo steroidogenesis and castration-resistant prostate cancer

Prostate cancer (PCa) is the most commonly diagnosed cancer in men in the Western world. The transition of androgen-dependent PCa to castration-resistant (CRPC) is a major clinical manifestation during disease progression and presents a therapeutic challenge. Our studies have shown that genetic ablation of inhibitor of differentiation 4 (Id4), a dominant-negative helix loop helix protein, in mice results in prostatic intraepithelial neoplasia lesions and decreased Nkx3.1 expression without the loss of androgen receptor (Ar) expression. ID4 is also epigenetically silenced in the majority of PCa. However, the clinical relevance and molecular pathways altered by ID4 inactivation in PCa are not known. This study investigates the effect of loss of ID4 in PCa cell lines on tumorigenicity and addresses the underlying mechanism. Stable silencing of ID4 in LNCaP cells (L-ID4) resulted in increased proliferation, migration, invasion, and anchorage-independent growth. An increase in the rate of tumor growth, weight, and volume was observed in L-ID4 xenografts compared with that in the LNCaP cells transfected with nonspecific short hairpin RNA (L+ns) in noncastrated mice. Interestingly, tumors were also observed in castrated mice, suggesting that loss of ID4 promotes CRPC. RNA sequence analysis revealed a gene signature mimicking that of constitutively active AR in L-ID4, which was consistent with gain of de novo steroidogenesis. Prostate-specific antigen expression as a result of persistent AR activation was observed in L-ID4 cells but not in L+ns cells. The results demonstrate that ID4 acts as a tumor suppressor in PCa, and its loss, frequently observed in PCa, promotes CRPC through constitutive AR activation.

Id1-induced IGF-II and its autocrine/endocrine promotion of esophageal cancer progression and chemoresistance--implications for IGF-II and IGF-IR-targeted therapy

PURPOSE

To investigate the autocrine/endocrine role of Id1-induced insulin-like growth factor-II (IGF-II) in esophageal cancer, and evaluate the potential of IGF-II- and IGF-type I receptor (IGF-IR)-targeted therapies.

EXPERIMENTAL DESIGN

Antibody array-based screening was used to identify differentially secreted growth factors from Id1-overexpressing esophageal cancer cells. In vitro and in vivo assays were performed to confirm the induction of IGF-II by Id1, and to study the autocrine and endocrine effects of IGF-II in promoting esophageal cancer progression. Human esophageal cancer tissue microarray was analyzed for overexpression of IGF-II and its correlation with that of Id1 and phosphorylated AKT (p-AKT). The efficacy of intratumorally injected IGF-II antibody and intraperitoneally injected cixutumumab (fully human monoclonal IGF-IR antibody) was evaluated using in vivo tumor xenograft and experimental metastasis models.

RESULTS

Id1 overexpression induced IGF-II secretion, which promoted cancer cell proliferation, survival, and invasion by activating AKT in an autocrine manner. Overexpression of IGF-II was found in 21 of 35 (60%) esophageal cancer tissues and was associated with upregulation of Id1 and p-AKT. IGF-II secreted by Id1-overexpressing esophageal cancer xenograft could instigate the growth of distant esophageal tumors, as well as promote metastasis of circulating cancer cells. Targeting IGF-II and IGF-IR had significant suppressive effects on tumor growth and metastasis in mice. Cixutumumab treatment enhanced the chemosensitivity of tumor xenografts to fluorouracil and cisplatin.

CONCLUSIONS

The Id1-IGF-II-IGF-IR-AKT signaling cascade plays an important role in esophageal cancer progression. Blockade of IGF-II/IGF-IR signaling has therapeutic potential in the management of esophageal cancer.

Id1 and NF-κB promote the generation of CD133+ and BMI-1+ keratinocytes and the growth of xenograft tumors in mice

Id1 and NF-κB are highly expressed in oral squamous cell carcinoma (OSCC). Whether they have a synergistic role in the carcinogenesis of OSCC is unclear. The current study was designed to demonstrate the synergy of both Id1 and NF-κB in the underlying disease mechanisms of OSCC using in vitro and in vivo animal models. Id1 and NF-κB strengthened the expression of both CD133 and BMI-1 in OSCC cell cultures. CD133(+) and BMI-1(+) keratinocytes from OSCC tissues and cell cultures initiated the growth of xenograft tumors in SCID/Beige mice. Id1 and NF-κB regulate the expression of CD133 and BMI-1 in an additive or synergistic manner in OSCC, which is associated with the generation of naïve and self-renewable keratinocytes and initiate the growth of xenograft tumors in vivo.

DJ-1 upregulates breast cancer cell invasion by repressing KLF17 expression

BACKGROUND

DJ-1 (PARK7) was reported as an oncogene in a Ras-dependent manner. Recent studies have shown that DJ-1 stimulates cell proliferation, cell invasion, and cancer metastasis. However, the molecular mehchanism by which DJ-1 induces cancer cell invasion and metastasis remains unclear.

METHODS

Breast cancer cells were transfected with DJ-1 siRNA or DJ-1 overexpression to investigate the effect of DJ-1 on KLF17 expression. ID-1 luciferase promoter assay was performed to evaluate DJ-1-dependent KLF17 expression changes. In addition, Epistasis analysis of DJ-1 and KLF17 was performed to evaluate their regulatory interactions. Ras inhibitors were pretreated to determine whether DJ-1 regulates cell invasion in a Ras-dependent manner.

RESULTS

I n the present study, we found increased DJ-1 expression in highly invasive breast cancer cells as compared with non-metastatic cells. Furthermore, DJ-1 promoted breast cancer cell invasion by downregulating E-cadherin and increasing Snail expression. Interestingly, exogenous DJ-1 overexpression markedly decreased mRNA and protein expression of KLF17, the EMT negative regulator. These data were confirmed by ID-1 promoter activity, which is directly regulated by DJ-1-dependent KLF17 transcription factor. Epistasis analysis showed that KLF17 overexpression overcomes increased cell invasion by DJ-1, suggesting that KLF17 might be one of the downstream signalling molecules of DJ-1. Acceleration of cell invasion by DJ-1 was alleviated by Ras inhibitors, suggesting that DJ-1 cooperates with Ras to increase cell invasion.

CONCLUSION

Altogether, these data suggest for the first time that DJ-1 acts as an EMT-positive regulator in breast cancer cells via regulation of the KLF17/ID-1 pathway.

Structure activity relationships of peptidic analogs of MyoD for the development of Id1 inhibitors as antiproliferative agents

Id proteins, inhibitors of DNA binding proteins, have highly conserved dimerization motif known as the helix-loop-helix (HLH) domain that acts as a negative regulator of basic HLH (bHLH) transcription factors. In signaling pathways, Id proteins play an important role in cellular development, proliferation, and differentiation. The mechanism of Id proteins is to antagonize bHLH proteins, thereby preventing them from binding to DNA and inhibiting transcription of cellular differentiation-associated genes in cancer. Recently, we reported an inhibitor of Id1, peptide 3C, which showed good affinity to Id1 protein and exhibited inhibitory effects in cancer cells. In this study, Ala (A)-substituted analogs of peptide 3C were synthesized by SPPS, purified by RP-HPLC, and characterized by MALDI-TOF MS. Binding of each peptide to Id1 or Id1-HLH (the HLH domain of Id1) was monitored by surface plasmon resonance (SPR)-based biosensor. Biological effect of each peptide in MCF-7 breast cancer cells was analyzed by MTT cell viability assay. The secondary structure of substituted analogs of peptide 3C was investigated by circular dichroism (CD) spectroscopy. SPR results revealed that A-substituted analogs of peptide 3C showed weaker binding to Id1 than that of peptide 3C, indicating that the six amino acid residues in the N-terminal of peptide 3C were all essential for binding to Id1 and the importance of amino acid residue was I(2)  > Q(6)  > Y(1)  > G(4)  > L(5)  > E(3). In addition, substitution of E(3) in peptide 3C with D, Q, and R did not improve the binding potency of peptide 3C. MTT assay demonstrated that neither A-substituted nor position 3-substituted analogs of peptide 3C showed increased antiproliferative effect in MCF-7 cancer cells. CD results indicated that peptide 3C exhibited the highest content of α-helical structure (39.37%), suggesting that the α-helical structure may contribute to its binding potency for Id1 and Id1-HLH. SAR results provided important information for the development of peptidic inhibitors of Id1 as anticancer agents and demonstrated peptide 3C as a promising lead for further modifications.

Transcriptome sequencing reveals differences between primary and secondary hair follicle-derived dermal papilla cells of the Cashmere goat (Capra hircus)

The dermal papilla is thought to establish the character and control the size of hair follicles. Inner Mongolia Cashmere goats (Capra hircus) have a double coat comprising the primary and secondary hair follicles, which have dramatically different sizes and textures. The Cashmere goat is rapidly becoming a potent model for hair follicle morphogenesis research. In this study, we established two dermal papilla cell lines during the anagen phase of the hair growth cycle from the primary and secondary hair follicles and clarified the similarities and differences in their morphology and growth characteristics. High-throughput transcriptome sequencing was used to identify gene expression differences between the two dermal papilla cell lines. Many of the differentially expressed genes are involved in vascularization, ECM-receptor interaction and Wnt/β-catenin/Lef1 signaling pathways, which intimately associated with hair follicle morphogenesis. These findings provide valuable information for research on postnatal morphogenesis of hair follicles.

Liver sinusoidal endothelial cells and liver regeneration

Liver sinusoidal endothelial cells (LSECs) have long been noted to contribute to liver regeneration after liver injury. In normal liver, the major cellular source of HGF is the hepatic stellate cell, but after liver injury, HGF expression has been thought to increase markedly in proliferating LSECs. However, emerging data suggest that even after injury, LSEC expression of HGF does not increase greatly. In contrast, bone marrow progenitor cells of LSECs (BM SPCs), which are rich in HGF, are recruited to the liver after injury. This Review examines liver regeneration from the perspective that BM SPCs that have been recruited to the liver, rather than mature LSECs, drive liver regeneration.

Decreased Expression of Inhibitor of DNA-binding (Id) Proteins and Vascular Endothelial Growth Factor and Increased Apoptosis in Ovarian Aging

This study examined the expression of inhibitor of DNA-binding (Id) proteins and vascular endothelial growth factor (VEGF) in the ovary according to female age using a mice model as the first step in investigating the potential role of Ids and VEGF in ovarian aging. C57BL inbred female mice of three age groups (6-9, 14-16, and 23-26 weeks) were injected with 5 IU pregnant mare’s serum gonadotropin (PMSG) in order to synchronize the estrus cycle. After 48 h, ovarian expression of Ids and VEGF was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR), western blot and immunohistochemistry. Ovarian apoptosis was examined by ovarian expression of Bcl-2 and Bcl-xL. Expression of Id-1 and VEGF was decreased with advancing female age, but not Id-2, Id-3, and Id-4. In particular, their expressions were significantly decreased in aged mice of 23-26 weeks compared with the young mice of 6-9 weeks (p < 0.05). In contrast, ovarian apoptosis was greatly increased in the aged mice compared to the young mice. This result suggests that Id-1 may have an implicated role in ovarian aging by associating with VEGF.

Susceptibility weighted imaging: a new tool in the diagnosis of prostate cancer and detection of prostatic calcification

BACKGROUND

Susceptibility weighted imaging (SWI) is a new MRI technique which has been proved very useful in the diagnosis of brain diseases, but few study was performed on its value in prostatic diseases. The aim of the present study was to investigate the value of SWI in distinguishing prostate cancer from benign prostatic hyperplasia and detecting prostatic calcification.

METHODOLOGY/PRINCIPAL FINDINGS

23 patients with prostate cancer and 53 patients with benign prostatic hyperplasia proved by prostate biopsy were scanned on a 3.0T MR and a 16-row CT scanner. High-resolution SWI, conventional MRI and CT were performed on all patients. The MRI and CT findings, especially SWI, were analyzed and compared. The analyses revealed that 19 out of 23 patients with prostate cancer presented hemorrhage within tumor area on SWI. However, in 53 patients with benign prostatic hyperplasia, hemorrhage was detected only in 1 patient in prostate by SWI. When comparing SWI, conventional MRI and CT in detecting prostate cancer hemorrhage, out of the 19 patients with prostate cancer who had prostatic hemorrhage detected by SWI, the prostatic hemorrhage was detected in only 7 patients by using conventional MRI, and none was detected by CT. In addition, CT demonstrated calcifications in 22 patients which were all detected by SWI whereas only 3 were detected by conventional MRI. Compared to CT, SWI showed 100% in the diagnostic sensitivity, specificity, accuracy, positive predictive value(PPV) and negative predictive value(NPV) in detecting calcifications in prostate but conventional MRI demonstrated 13.6% in sensitivity, 100% in specificity, 75% in accuracy, 100% in PPV and 74% in NPV.

CONCLUSIONS

More apparent prostate hemorrhages were detected on SWI than on conventional MRI or CT. SWI may provide valuable information for the differential diagnosis between prostate cancer and prostatic hyperplasia. Filtered phase images can identify prostatic calcifications as well as CT.

Improvement of ovarian response and oocyte quality of aged female by administration of bone morphogenetic protein-6 in a mouse model

BACKGROUND

Advancing female age remains a difficult problem in infertility treatment. Ovarian angiogenesis plays an important role in follicular development and the activation of ovarian angiogenesis has been emerged as a new strategy for the improvement of age-related decline of oocyte quality. BMP-6 affect gonadotropin signals in granulosa cells and it promotes normal fertility by enabling appropriate response to LH and normal oocyte quality. BMP-6 has a potential role in regulation of angiogenesis and regulates the expression of inhibitor of DNA-binding proteins (Ids). Ids involved in the control and timing of follicle selection and granulosa cells differentiation. Especially, Id-1 is well-characterized target of BMP-6 signaling. Therefore, this study investigated whether co-administration of BMP-6 during superovulation process improves ovarian response, oocyte quality and expression of Id-1 and vascular endothelial growth factor (VEGF) in the ovary of aged female using a mouse model.

METHODS

Aged C57BL/6 female mice (26-31 weeks old) were superovulated by injection with 0.1 mL of 5 IU equine chorionic gonadotropin (eCG) containing recombinant mouse BMP-6 at various doses (0, 0.01, 0.1, 1, and 10 ng), followed by injection with 5 IU human chorionic gonadotropin (hCG) 48 h later. Then, the mice were immediately paired with an individual male. The aged control group was superovulated without BMP-6. Young mice of 6-9 weeks old were superovulated without BMP-6 as a positive control for superovulation and in vitro culture of embryos. Eighteen hours after hCG injection, zygotes were retrieved and cultured for 4 days. Both ovaries of each mouse were provided in the examination of ovarian expression of Id-1 and VEGF by reverse transcriptase-polymerase chain reaction, western blot, and immunohistochemistry.

RESULTS

Administration of 0.1 ng BMP-6 significantly increased the number and blastocyst formation rate of oocytes ovulated and ovarian expression of Id-1 and VEGF compared to aged control mice. These increased levels were comparable to those of young control mice.

CONCLUSIONS

This result suggests that BMP-6 during ovulation induction plays an important role in improvement of oocyte quality and ovarian response of aged female, possibly by regulating of ovarian Id-1 and VEGF expression.

Expression and localization of inhibitor of differentiation (ID) proteins during tissue and vascular remodelling in the human corpus luteum

Members of the transforming growth factor-β (TGF-β) superfamily are likely to have major roles in the regulation of tissue and vascular remodelling in the corpus luteum (CL). There are four inhibitor-of-differentiation (ID1-4) genes that are regulated by members of the TGF-β superfamily and are involved in the transcriptional regulation of cell growth and differentiation. We studied their expression, localization and regulation in dated human corpora lutea from across the luteal phase (n = 22) and after human chorionic gonadotrophin (hCG) administration in vivo (n = 5), and in luteinized granulosa cells (LGCs), using immunohistochemistry and quantitative RT-PCR. ID1-4 can be localized to multiple cell types in the CL across the luteal phase. Endothelial cell ID3 (P < 0.05) and ID4 (P < 0.05) immunostaining intensities peak at the time of angiogenesis but overall ID1 (P < 0.05) and ID3 (P < 0.05) expression peaks at the time of luteolysis, and luteal ID3 expression is inhibited by hCG in vivo (P < 0.01). In LGC cultures in vitro, hCG had no effect on ID1, down-regulated ID3 (P < 0.001), and up-regulated ID2 (P < 0.001) and ID4 (P < 0.01). Bone morphogenic proteins (BMPs) had no effect on ID4 expression but up-regulated ID1 (P < 0.01 to P < 0.005). BMP up-regulation of ID2 (P < 0.05) was additive to the hCG up-regulation of ID2 expression (P < 0.001), while BMP cancelled out the down regulative effect of hCG on ID3 regulation. As well as documenting regulation patterns specific for ID1, ID2, ID3 and ID4, we have shown that IDs are located and differentially regulated in the human CL, suggesting a role in the transcriptional regulation of luteal cells during tissue and vascular remodelling.

Embryonic protein nodal promotes breast cancer vascularization

Tumor vascularization is requisite for breast cancer progression, and high microvascular density in tumors is a poor prognostic indicator. Patients bearing breast cancers expressing human embryonic stem cell (hESC)-associated genes similarly exhibit high mortality rates, and the expression of embryonic proteins is associated with tumor progression. Here, we show that Nodal, a hESC-associated protein, promotes breast cancer vascularization. We show that high levels of Nodal are positively correlated with high vascular densities in human breast lesions (P = 0.0078). In vitro, we show that Nodal facilitates breast cancer-induced endothelial cell migration and tube formation, largely by upregulating the expression and secretion of proangiogenic factors by breast cancer cells. Using a directed in vivo angiogenesis assay and a chick chorioallantoic membrane assay, we show that Nodal promotes vascular recruitment in vivo. In a clinically relevant in vivo model, whereby Nodal expression was inhibited following tumor formation, we found a significant reduction in tumor vascularization concomitant with elevated hypoxia and tumor necrosis. These findings establish Nodal as a potential target for the treatment of breast cancer angiogenesis and progression.

ID1 and ID3 regulate the self-renewal capacity of human colon cancer-initiating cells through p21

There is increasing evidence that some cancers are hierarchically organized, sustained by a relatively rare population of cancer-initiating cells (C-ICs). Although the capacity to initiate tumors upon serial transplantation is a hallmark of all C-ICs, little is known about the genes that control this process. Here, we establish that ID1 and ID3 function together to govern colon cancer-initiating cell (CC-IC) self-renewal through cell-cycle restriction driven by the cell-cycle inhibitor p21. Regulation of p21 by ID1 and ID3 is a central mechanism preventing the accumulation of excess DNA damage and subsequent functional exhaustion of CC-ICs. Additionally, silencing of ID1 and ID3 increases sensitivity of CC-ICs to the chemotherapeutic agent oxaliplatin, linking tumor initiation function with chemotherapy resistance.

Effect of Id1 knockdown on formation of osteolytic bone lesions by prostate cancer PC3 cells in vivo

The formation of osteolytic bone lesions is a key process for osteolytic cancer to metastasize to the bone and is under the control of a set of transcription factors. Recently, the inhibitor of differentiation 1 (Id1) has been linked with angiogenesis, tumorigenesis, metastasis and bone formation. However, the function of Id1 during the process of bone destruction caused by cancer in vivo has not yet been elucidated. We, therefore, examined whether and how Id1 affects the ability of cancer to form osteolytic lesion in vivo. The study used a lentiviral vector overexpressing short hairpin RNA (shRNA) targeting Id1 gene. PC3 cells, a prostate cancer cell line, were transduced with Id1 shRNA or negative control (NC) shRNA before implantation in BALB/c mice. Cells were implanted in a tibial injection model. Tumor formation in bone was monitored by X-ray. The relationship between parathyroid hormone-related protein (PTHrP), an osteolytic factor, and Id1 was analyzed by using immunohistochemistry in tissue sections from osteolytic lesion of the BALB/c mice. Our results showed that Id1 shRNA delivery to PC3 cells by lentivirus caused efficient and stable Id1 gene silencing. In the intratibial model, PC3 cells produced primarily osteolytic lesions in the bone. Eleven of 14 mice in Id1 shRNA group but only 4 of 14 mice in the NC shRNA group developed osteolytic lesions with cortical destruction at 4th week. Mice treated with Id1 shRNA had larger tumor volume in the bone and larger cortical destruction. The expression of PTHrP protein in PC3 cells was not affected by Id1 knockdown in vivo. These results indicate that Id1 may down-regulate the ability of PC3 cells to form osteolytic lesions in vivo and the signal pathway needs to be further investigated.

A novel role of Id-1 in regulation of epithelial-to-mesenchymal transition in bladder cancer

BACKGROUND AND OBJECTIVE

Inhibitor of differentiation or DNA binding -1 (Id-1) has been shown to be increased in several types of advanced cancer, and to be associated with aggressive and metastatic abilities of cancer cells. Recently, more and more evidence indicates that epithelial-to-mesenchymal transition (EMT) is an important mechanism taking place during tumor invasion and metastasis, but the molecular pathways underlying EMT have not been clearly established. This study was to investigate the expression of Id-1 in bladder cancer and its association with EMT.

MATERIALS AND METHODS

A total of 169 tissues, consisting of 147 primary bladder cancers and 22 adjacent normal tissues were included in this study. Id-1, E-cadherin, and β-catenin were examined immunohistochemically in paraffin sections. The pBabe-Id-1 expression retroviral vector and retroviral vectors containing an Id-1-specific small interfering RNA oligonucleotides (si-Id-1) were transfected into 2 bladder cancer cell lines respectively. Then, we used Western blotting and immunofluorescent staining to detect the cellular expression of epithelial markers and mesenchymal markers. The invasion and migration ability of bladder cancer cells were identified by type I collagen invasion assay and wound closure assay.

RESULTS

We demonstrated that increased Id-1 expression was associated with advanced tumor stage and grade. In addition, the increased Id-1 expression in bladder tumors was also correlated with decreased membranous E-cadherin and β-catenin expression. In vitro, studies showed that inactivation of the Id-1 gene conferred morphologic transition of bladder cancer cells from a fibroblastic to epithelial appearance, and overexpression of Id-1 could lead to acquisition of a fibroblastic spindle cell phenotype accompanied by loss of cell-to-cell contacts. By Western blotting and immunofluorescent staining, we showed that the expression level of Id-1 was correlated with the expression of mesenchymal markers but was inversely correlated with the expression of epithelial markers. Moreover, results of collagen invasion and wound closure assays showed ectopic Id-1 expression led to increased ability of invasion and migration.

CONCLUSIONS

Our results suggest that Id-1 may play roles in tumor progression and EMT activation in bladder cancer.

Acheron regulates vascular endothelial proliferation and angiogenesis together with Id1 during wound healing

RNA binding protein acheron has proved to be either the mediator of integrin-extracellular matrix interactions or the regulatory factor that participates in vertebrate development, cell differentiation and cell death. We report the role of acheron in vascular endothelial proliferation, angiogenesis and wound healing post-trauma. Co-immunoprecipitation showed that Acheron forms a ternary complex with β1 integrin and Id1 in human umbilical vein endothelial cells following stimulation with serious trauma serum. Acheron, vascular endothelial growth factor (VEGF), and β1 integrin mRNA expression was apparently inhibited, and capillary density and wound healing rate also were reduced in Id1-deficient mice trauma model. Acheron together with Id1 significantly induces VEGF, not CD105 level inhibition by serious trauma serum for 24 h. In conclusion, we have demonstrated that acheron may be an effective mediator of promoting endothelial proliferation, angiogenesis and wound healing probably by regulating VEGF together with Id1.

Bone morphogenetic protein modulator BMPER is highly expressed in malignant tumors and controls invasive cell behavior

Bone morphogenetic proteins (BMPs) are growth factors that exert important functions in cell proliferation, migration and differentiation. Till date, multiple human tumors have been reported to display a dysregulation of several members of the BMP pathway that is associated with enhanced malignant tumor growth and metastasis. BMPER (BMP endothelial cell precursor-derived regulator) is a direct BMP modulator that is necessary for BMPs to exert their full-range signaling activity. Moreover, BMPER is expressed by endothelial cells and their progenitors, and has pro-angiogenic features in these cells. Here, we describe the expression of BMPER in human specimens of lung, colon and cervix carcinomas and cell lines derived from such carcinomas. In contrast to healthy tissues, BMPER is highly expressed upon malignant deterioration. Functionally, loss of BMPER in the lung tumor cell line A549 impairs proliferation, migration, invasion as well as tumor cell-induced endothelial cell sprout formation. In contrast, stimulation of A549 cells with exogenous BMPER had no further effect. We found that the BMPER effect may be transduced by regulation of the BMP target transcription factor inhibitor of DNA binding 1 (Id1) and matrix metalloproteinases (MMPs) 9 and 2. These facilitators of cell migration are downregulated when BMPER is absent. To prove the relevance of our in vitro results in vivo, we generated Lewis lung carcinoma cells with impaired BMPER expression and implanted them into the lungs of C57BL/6 mice. In this model, the absence of BMPER resulted in severely reduced tumor growth and tumor angiogenesis. Taken together, these data unequivocally demonstrate that the BMP modulator BMPER is highly expressed in malignant tumors and tumor growth is dependent on the presence of BMPER.

Induction of Id-1 by FGF-2 involves activity of EGR-1 and sensitizes neuroblastoma cells to cell death

Inhibitor of differentiation-1 (Id-1) is a member of helix-loop-helix (HLH) family of proteins that regulate gene transcription through their inhibitory binding to basic-HLH transcription factors. Similarly to other members of this family, Id-1 is involved in the repression of cell differentiation and activation of cell growth. The dual function of Id-1, inhibition of differentiation, and stimulation of cell proliferation, might be interdependent, as cell differentiation is generally coupled with the exit from the cell cycle. Fibroblast growth factor-2 (FGF-2) has been reported to play multiple roles in different biological processes during development of the central nervous system (CNS). In addition, FGF-2 has been described to induce "neuronal-like" differentiation and trigger apoptosis in neuroblastoma SK-N-MC cells. Although regulation of Id-1 protein by several mitogenic factors is well-established, little is known about the role of FGF-2 in the regulation of Id-1. Using human neuroblastoma cell line, SK-N-MC, we found that treatment of these cells with FGF-2 resulted in early induction of both Id-1 mRNA and protein. The induction occurs within 1 h from FGF-2 treatment and is mediated by ERK1/2 pathway, which in turn stimulates expression of the early growth response-1 (Egr-1) transcription factor. We also demonstrate direct interaction of Egr-1 with Id-1 promoter in vitro and in cell culture. Finally, inhibition of Id-1 expression results in G(2) /M accumulation of FGF-2-treated cells and delayed cell death.

ID1 facilitates the growth and metastasis of non-small cell lung cancer in response to nicotinic acetylcholine receptor and epidermal growth factor receptor signaling

Expression of ID1 (inhibitor of differentiation) has been correlated with the progression of a variety of cancers, but little information is available on its role in non-small cell lung cancer (NSCLC). Here we show that ID1 is induced by nicotinic acetylcholine receptor (nAChR) and epidermal growth factor receptor (EGFR) signaling in a panel of NSCLC cell lines and primary cells from the lung. ID1 induction was Src dependent and mediated through the α7 subunit of nAChR; transfection of K-Ras or EGFR to primary cells induced ID1. ID1 depletion prevented nicotine- and EGF-induced proliferation, migration, and invasion of NSCLC cells and angiogenic tubule formation of human microvascular endothelial cells from lungs (HMEC-Ls). ID1 could induce the expression of mesenchymal markers such as vimentin and fibronectin by downregulating ZBP-89, a zinc finger repressor protein. ID1 levels were elevated in tumors from mice that were exposed to nicotine. Further, human lung tissue microarrays (TMAs) showed elevated levels of ID1 in NSCLC samples, with maximal levels in metastatic lung cancers. Quantitative reverse transcription-PCR (RT-PCR) performed on patient lung tumors showed that ID1 levels were elevated in advanced stages of NSCLC and correlated with elevated expression of vimentin and fibronectin, irrespective of smoking history.

ID4: a new player in the cancer arena

Id proteins (Id-1 to 4) are dominant negative regulators of basic helix-loop-helix transcription factors. They play a key role during development, preventing cell differentiation while inducing cell proliferation. They are poorly expressed in adult life but can be reactivated in tumorigenesis. Several evidences indicate that Id proteins are associated with loss of differentiation, unrestricted proliferation and neoangiogenesis in diverse human cancers. Recently, we identified Id4 as a transcriptional target of the protein complex mutant p53/E2F1/p300 in breast cancer. Id4 protein binds, stabilizes and enhances the translation of mRNAs encoding proangiogenic cytokines, such as IL8 and GRO-alpha, increasing the angiogenic potential of cancer cells. We present here an overview of the current experimental data that links Id4 to cancer. We provide evidence also of the induction of Id4 following anticancer treatments in mutant p53- carrying cells. Indeed, mutant p53 is recruited to a specific region of the Id4 promoter upon DNA damage. Our findings indicate that Id4, besides its proangiogenic role, might also participate in the chemoresistance associated to mutant p53 proteins exerting gain of function activities.

Members of the CREB/ATF and AP1 family of transcription factors are involved in the regulation of SOX18 gene expression

The SOX18 transcription factor plays an important role in endothelial cell specification, angiogenesis and atherogenesis. By profiling transcription factor interactions (TranSignal TM TF Protein Array) we identified several transcription factors implicated in angiogenesis that have the ability to bind to the SOX18 optimal promoter region in vitro. In this report we focused our attention on distinct transcription factors identified by the array as belonging to AP-1 and CREB/ATF protein families. In particular, we analyzed the effects of CREB, JunB, c-Jun and ATF3 on SOX18 gene expression. Functional analysis revealed that CREB acts as a repressor, while JunB, c-Jun and ATF3 act as activators of SOX18 promoter activity. Our findings indicate that a transcriptional network that includes CREB, JunB, c-Jun and ATF3 could be involved in angiogenesis-related transcriptional regulation of the SOX18 gene.