Overexpression of Id-1 is associated with poor clinical outcome in node negative breast cancer

KIS, a target of SOX4, regulates the ID1-mediated enhancement of β-catenin to facilitate lung adenocarcinoma cell proliferation and metastasis

PURPOSE

Kinase interacting with stathmin (KIS) is a serine/threonine kinase involved in RNA processing and protein phosphorylation. Increasing evidence has suggested its involvement in cancer progression. The aim of this study was to investigate the role of KIS in the development of lung adenocarcinoma (LUAD). Dual luciferase assay was used to explore the relationship between KIS and SOX4, and its effect on ID1/β-catenin pathway.

METHODS

Real-time qPCR and western blot were used to assess the levels of KIS and other factors. Cell proliferation, migration, and invasion were monitored, and xenograft animal model were established to investigate the biological functions of KIS in vitro and in vivo.

RESULTS

In the present study, KIS was found to be highly expressed in LUAD tissues and cell lines. KIS accelerated the proliferative, migratory and invasive abilities of LUAD cells in vitro, and promoted the growth of LUAD in a mouse tumor xenograft model in vivo. Mechanistically, KIS activated the β-catenin signaling pathway by modulating the inhibitor of DNA binding 1 (ID1) and was transcriptionally regulated by SOX4 in LUAD cells.

CONCLUSION

KIS, a target of SOX4, regulates the ID1-mediated enhancement of β-catenin to facilitate LUAD cell invasion and metastasis.

Silibinin is a suppressor of the metastasis-promoting transcription factor ID3

BACKGROUND

ID3 (inhibitor of DNA binding/differentiation-3) is a transcription factor that enables metastasis by promoting stem cell-like properties in endothelial and tumor cells. The milk thistle flavonolignan silibinin is a phytochemical with anti-metastatic potential through largely unknown mechanisms.

HYPOTHESIS/PURPOSE

We have mechanistically investigated the ability of silibinin to inhibit the aberrant activation of ID3 in brain endothelium and non-small cell lung cancer (NSCLC) models.

METHODS

Bioinformatic analyses were performed to investigate the co-expression correlation between ID3 and bone morphogenic protein (BMP) ligands/BMP receptors (BMPRs) genes in NSCLC patient datasets. ID3 expression was assessed by immunoblotting and qRT-PCR. Luciferase reporter assays were used to evaluate the gene sequences targeted by silibinin to regulate ID3 transcription. In silico computational modeling and LanthaScreen TR-FRET kinase assays were used to characterize and validate the BMPR inhibitory activity of silibinin. Tumor tissues from NSCLC xenograft models treated with oral silibinin were used to evaluate the in vivo anti-ID3 effects of silibinin.

RESULTS

Analysis of lung cancer patient datasets revealed a top-ranked positive association of ID3 with the BMP9 endothelial receptor ACVRL1/ALK1 and the BMP ligand BMP6. Silibinin treatment blocked the BMP9-induced activation of the ALK1-phospho-SMAD1/5-ID3 axis in brain endothelial cells. Constitutive, acquired, and adaptive expression of ID3 in NSCLC cells were all significantly downregulated in response to silibinin. Silibinin blocked ID3 transcription via BMP-responsive elements in ID3 gene enhancers. Silibinin inhibited the kinase activities of BMPRs in the micromolar range, with the lower IC50 values occurring against ACVRL1/ALK1 and BMPR2. In an in vivo NSCLC xenograft model, tumoral overexpression of ID3 was completely suppressed by systematically achievable oral doses of silibinin.

CONCLUSIONS

ID3 is a largely undruggable metastasis-promoting transcription factor. Silibinin is a novel suppressor of ID3 that may be explored as a novel therapeutic approach to interfere with the metastatic dissemination capacity of NSCLC.

Proactive and reactive roles of TGF-β in cancer

Cancer cells adapt to varying stress conditions to survive through plasticity. Stem cells exhibit a high degree of plasticity, allowing them to generate more stem cells or differentiate them into specialized cell types to contribute to tissue development, growth, and repair. Cancer cells can also exhibit plasticity and acquire properties that enhance their survival. TGF-β is an unrivaled growth factor exploited by cancer cells to gain plasticity. TGF-β-mediated signaling enables carcinoma cells to alter their epithelial and mesenchymal properties through epithelial-mesenchymal plasticity (EMP). However, TGF-β is a multifunctional cytokine; thus, the signaling by TGF-β can be detrimental or beneficial to cancer cells depending on the cellular context. Those cells that overcome the anti-tumor effect of TGF-β can induce epithelial-mesenchymal transition (EMT) to gain EMP benefits. EMP allows cancer cells to alter their cell properties and the tumor immune microenvironment (TIME), facilitating their survival. Due to the significant roles of TGF-β and EMP in carcinoma progression, it is essential to understand how TGF-β enables EMP and how cancer cells exploit this plasticity. This understanding will guide the development of effective TGF-β-targeting therapies that eliminate cancer cell plasticity.

Therapeutic targeting of prenatal pontine ID1 signaling in diffuse midline glioma

BACKGROUND

Diffuse midline gliomas (DMG) are highly invasive brain tumors with rare survival beyond two years past diagnosis and limited understanding of the mechanism behind tumor invasion. Previous reports demonstrate upregulation of the protein ID1 with H3K27M and ACVR1 mutations in DMG, but this has not been confirmed in human tumors or therapeutically targeted.

METHODS

Whole exome, RNA, and ChIP-sequencing was performed on the ID1 locus in DMG tissue. Scratch-assay migration and transwell invasion assays of cultured cells were performed following shRNA-mediated ID1-knockdown. In vitro and in vivo genetic and pharmacologic [cannabidiol (CBD)] inhibition of ID1 on DMG tumor growth was assessed. Patient-reported CBD dosing information was collected.

RESULTS

Increased ID1 expression in human DMG and in utero electroporation (IUE) murine tumors is associated with H3K27M mutation and brainstem location. ChIP-sequencing indicates ID1 regulatory regions are epigenetically active in human H3K27M-DMG tumors and prenatal pontine cells. Higher ID1-expressing astrocyte-like DMG cells share a transcriptional program with oligo/astrocyte-precursor cells (OAPCs) from the developing human brain and demonstrate upregulation of the migration regulatory protein SPARCL1. Genetic and pharmacologic (CBD) suppression of ID1 decreases tumor cell invasion/migration and tumor growth in H3.3/H3.1K27M PPK-IUE and human DIPGXIIIP* in vivo models of pHGG. The effect of CBD on cell proliferation appears to be non-ID1 mediated. Finally, we collected patient-reported CBD treatment data, finding that a clinical trial to standardize dosing may be beneficial.

CONCLUSIONS

H3K27M-mediated re-activation of ID1 in DMG results in a SPARCL1+ migratory transcriptional program that is therapeutically targetable with CBD.

Prominent Prognostic Factors in Aggressive Breast Cancer: A Review

Context: Breast cancer (BC) is the most common cancer in women worldwide. Hereditary susceptibility created by mutations in autosomal dominant genes is responsible for 5 to 10% of all BC cases in women. Recent studies have identified genes associated with increased risk for aggressive BC, providing the basis for better risk management. Evidence Acquisition: The latest information in National Center for Biotechnology Information (NCBI), Google Scholar, ScienceDirect, and Scopus were the main databases for finding articles. A combination of keywords of ‘metastasis’, ‘invasion’, ‘aggressive breast cancer’, ‘prognostic factor’, ‘mutation’, and ‘cancer treatment’ was searched in the databases to identify related articles. Titles and abstracts of the articles were studied to choose the right articles. Results: Mutations in breast cancer type 1 susceptibility protein (BRCA1) and breast cancer type 2 susceptibility protein (BRCA2) genes are two central players related to the high risk of BC. Mutation in tumor protein p53 (TP53) is another important mutation that leads to triple-negative BC. Although the majority of BC types are not associated with high-throughput mutant genes such as BRCA1, BRCA2, and TP53, they are associated with low-throughput genes, including DNA repair protein Rad50 (RAD50), Nijmegen breakage syndrome gene (NBS1), checkpoint kinase 2 (CHEK2), BRCA1-interacting protein 1 (BRIP1), E-cadherin gene (CDH1) and PALB2, UCHL1, aldehydedehydrogenase1A3 (ALDH1A3), androgen receptor (AR), 5-bisphosphate 3-kinase (PIK3CA), phosphatidylinositol-4, and luminal gene expression that are generally mutated in the global population. High tumor mutational burden (TMB) was associated with improved progression-free survival. Conclusions: The lymph node status, early tumor size, ER, PR, human epidermal growth factor receptor-2 (HER2), and Ki-67 are conventional prognostic factors for BC. However, these factors cannot exactly predict the aggressive behavior of BC. Hence, in this review, we discussed new prognostic factors of aggressive BCs that are useful for the treatment of patients with BC.

Anti-tumor effects of an ID antagonist with no observed acquired resistance

ID proteins are helix-loop-helix (HLH) transcriptional regulators frequently overexpressed in cancer. ID proteins inhibit basic-HLH transcription factors often blocking differentiation and sustaining proliferation. A small-molecule, AGX51, targets ID proteins for degradation and impairs ocular neovascularization in mouse models. Here we show that AGX51 treatment of cancer cell lines impairs cell growth and viability that results from an increase in reactive oxygen species (ROS) production upon ID degradation. In mouse models, AGX51 treatment suppresses breast cancer colonization in the lung, regresses the growth of paclitaxel-resistant breast tumors when combined with paclitaxel and reduces tumor burden in sporadic colorectal neoplasia. Furthermore, in cells and mice, we fail to observe acquired resistance to AGX51 likely the result of the inability to mutate the binding pocket without loss of ID function and efficient degradation of the ID proteins. Thus, AGX51 is a first-in-class compound that antagonizes ID proteins, shows strong anti-tumor effects and may be further developed for the management of multiple cancers.

ID1 and ID4 Are Biomarkers of Tumor Aggressiveness and Poor Outcome in Immunophenotypes of Breast Cancer

Simple Summary

Inhibitor of differentiation (ID) proteins are essential to promote proliferation during embryonic development, but they are silenced in most adult tissues. Evidence to date shows ID1 expression in many tumor types, including breast cancer. However, the role of the remaining ID family members, especially ID4, in breast cancer remains unclear. In this work, we aimed to assess the four ID genes expression in breast cancer cell lines and a long series of breast cancer samples and correlate them with clinicopathological features and patients’ survival. We observed a significantly higher expression of ID4 in tumor cell lines than the healthy breast epithelium cell line. We confirmed that the overexpression of ID1 and ID4 correlated with more aggressive phenotypes and poor survival in breast cancer patients’ samples. Our results support the importance of ID proteins as targets for the development of anti-cancer drugs.

Abstract

Inhibitor of differentiation (ID) proteins are a family of transcription factors that contribute to maintaining proliferation during embryogenesis as they avoid cell differentiation. Afterward, their expression is mainly silenced, but their reactivation and contribution to tumor development have been suggested. In breast cancer (BC), the overexpression of ID1 has been previously described. However, whether the remaining ID genes have a specific role in this neoplasia is still unclear. We studied the mRNA expression of all ID genes by q RT-PCR in BC cell lines and 307 breast carcinomas, including all BC subtypes. Our results showed that ID genes are highly expressed in all cell lines tested. However, ID4 presented higher expression in BC cell lines compared to a healthy breast epithelium cell line. In accordance, ID1 and ID4 were predominantly overexpressed in Triple-Negative and HER2-enriched samples. Moreover, high levels of both genes were associated with larger tumor size, histological grade 3, necrosis and vascular invasion, and poorer patients’ outcomes. In conclusion, ID1 and ID4 may act as biomarkers of tumor aggressiveness and worse prognosis in breast cancer, and they could be used as potential targets for new treatments discover.

Prognostic ability of DNA-binding protein inhibitor ID-1 expression in patients with oral squamous cell carcinoma

DNA-binding protein inhibitor ID-1 (ID-1) plays a vital role in the development of cancer. In the present study, ID-1 expression in oral squamous cell carcinoma (OSCC), and its association with prognosis were investigated in 128 patients with OSCC, treated at the Qilu Hospital of Shandong University and followed up for an additional 10 years. Immunohistochemical analysis was performed to detect ID-1 expression, and the association between ID-1 expression and recurrence, and estimated disease-specific survival (DSS) time were subsequently analyzed using the Mann-Whitney U test and the Kaplan-Meier method, respectively. In addition, the log-rank test was implemented to compare the survival curves and multivariate Cox proportional hazards analysis was performed to assess the prognostic value of ID-1. The results demonstrated that ID-1 was highly expressed in the majority of OSCC tissues investigated, and ID-1 expression was significantly higher in cases with recurrence of local tumors and lymph node metastasis. Furthermore, higher ID-1 expression levels were associated with a shorter DSS time. Taken together, the results of the present study suggest that ID-1 may serve as an independent prognostic factor to predict DSS time in patients with OSCC.

Inhibitor of DNA binding 1 (Id1) mediates stemness of colorectal cancer cells through the Id1-c-Myc-PLAC8 axis via the Wnt/β-catenin and Shh signaling pathways

Background

Inhibitor of DNA binding 1 (Id1) is upregulated in multiple cancers, and Id1overexpression correlates with cancer aggressiveness and poor clinical outcomes in cancer patients. However, its roles in cancer stem-like cells (CSCs) and epithelial-mesenchymal transition (EMT) are still elusive.

Purpose

This study aimed to examine the role of Id1 on the mediation of CRC stemness and explore the underlying mechanisms.

Methods

Id1 and CD133 expression was detected by qPCR assay and immunohistochemistry (IHC) in normal mucosal and primary colorectal cancer (CRC) specimens. Id1 was stably knocked down (KD) in human CRC cell lines. Spheres forming assay and tumorigenic assay were performed to evaluate self-renewal capacity and tumor initiation. Expression of CSC- and EMT-related markers and TCF/LEF activity were assessed in HCT116 cells after Id1 KD.

Results

qPCR assay showed higher Id1 and CD133 expression in CRC specimens than in normal mucosal specimens (P<0.05). IHC detected high cytoplasmic Id1 expression in 35 CRC specimens (46.7%), and high CD133 expression in 22 CRC specimens (29.3%) and negative expression in 18 normal mucosal specimens. High Id1 expression positively correlated with poor differentiation (P=0.034), and CD133 expression correlated with T category in CRC patients (P=0.002). Spearman correlation analysis revealed a positive correlation between Id1 and CD133 expression in CRC patients (P<0.05). Id1 KD resulted in suppression of proliferation, cell-colony formation, self-renewal capability and CSC-like features in HCT116 cells, and impaired the tumor-initiating capability in CRC cells. In addition, Id1 maintained the stemness of CRC cells via the Id1-c-Myc-PLAC8 axis through activating the Wnt/β-catenin and Shh signaling pathways.

Conclusions

Id1 expression significantly correlates with CD133 expression in CRC patients, and Id1 KD impairs CSC-like capacity and reverses EMT traits, partially via the Wnt/β-catenin signaling. Id1 may be a promising therapeutic target against colon CSCs.

Expression analysis of Inhibitor Of DNA Binding 1 (ID-1) gene in breast cancer

BACKGROUND

ID-1 gene codes for a helix-loop-helix (HLH) protein that inhibits the DNA binding and transcriptional activation function of these proteins.

METHODS

We analyzed ID-1 expression in microarray and RNA Sequencing databases as well as 61 breast cancer tissues compared with adjacent non-cancerous tissues (ANCTs).

RESULTS

Expression analysis of ID-1 gene in two microarray datasets and RNA sequencing data showed down-regulation of ID-1 in tumoral tissues compared with normal tissues. However, ID-1 expression analysis in tumoral tissues and ANCTs obtained from 61 patients revealed its over-expression in tumoral tissues. A negative association was detected between ID-1 expression levels and ER status.

CONCLUSION

ID-1 expression may be implicated in the pathogenesis of breast cancer especially in patient with ER negative status.

Strong expression of Id-1 in metastatic lymph nodes from esophageal squamous cell carcinoma is associated with better clinical outcome

Background

Over-expression of inhibitor of differentiation or DNA binding 1 (Id-1) is associated with poor prognosis in esophageal squamous cell carcinoma (ESCC). However, some biomarkers discordant expression in metastasis has been reported previously. We aimed to confirm possible differential expression and prognostic value of Id-1 in paired metastatic lymph node (PMLN).

Methods

Expression of Id-1 in primary tumors (PT) and paired regional metastatic lymph nodes of ESCC were evaluated with immunohistochemical (IHC) analysis. Statistical analysis of Kaplan-Meier method was performed to test the prognostic significance of Id-1 expression.

Results

The expression of Id-1 was down-regulated in metastatic lymph nodes compared with primary esophageal tumors (P<0.001). Patients with 1 to 2 lymph nodes involved had significantly higher Id-1 expression in metastatic lymph nodes (P=0.028). The similar association was observed between a ratio of involved to examined lymph nodes ≤0.2 and high level Id-1 expression in lymphatic metastases (P=0.011). Better overall survival with statistical significance was observed in patients with higher level Id-1 expression in metastatic lymph nodes (P=0.015). The results of Id-1 expression in metastatic lymph node and paired PT was to predict prognosis effective in out cohort (P=0.035).

Conclusions

The level of Id-1 protein expression was down-regulated from PT to metastatic lymph node. It was contrary to previous studies that strong expression of Id-1 in metastatic lymph nodes was associated with better clinical outcomes in patients with stage T3N1-3M0 ESCC.

KIF-2C expression is correlated with poor prognosis of operable esophageal squamous cell carcinoma male patients

To determine the prognostic significance of Kinesin family member 2C (KIF-2C) expression in patients with operable esophageal squamous cell carcinoma (ESCC), we conducted an immunohistochemical analysis of KIF-2C expression in 415 surgically resected primary tumor tissues and 40 adjacent non-cancerous tissues from patients with operable ESCC. The median duration of postoperative follow-up was 76.0 months. Higher KIF-2C expression was associated with significantly increased risks of higher pathologic tumor (pT) status (P=0.038) and poorer tumor differentiation (P=0.022). For the entire cohort, KIF-2C expression was not an independent factor significantly associated with overall survival (OS) (P=0.097) or disease-free survival (DFS) (P=0.152). In female patients, KIF-2C expression had no effect on OS (P=0.880) and DFS (P=0.864). However, OS (hazard ratio (HR)=1.480, P=0.013) and DFS (HR=1.418, P=0.024) were worse for male patients with high KIF-2C expression compared with male patients with low KIF-2C expression. Moreover, the OS and DFS of male patients with high KIF-2C expression were also significantly shorter compared with female patients with low KIF-2C expression (P=0.022, P=0.029) and female patients with high KIF-2C expression (P=0.014, P=0.018). Based on these findings, KIF-2C expression in tumor tissues promises to serve as an independent prognostic marker for male, but not female, patients with operable ESCC. Prognosis was worse for male patients with high KIF-2C expression compared with patients with the same pathologic tumor-node-metastasis (pTNM) stage.

Cancer cell-secreted IGF2 instigates fibroblasts and bone marrow-derived vascular progenitor cells to promote cancer progression

Local interactions between cancer cells and stroma can produce systemic effects on distant organs to govern cancer progression. Here we show that IGF2 secreted by inhibitor of differentiation (Id1)-overexpressing oesophageal cancer cells instigates VEGFR1-positive bone marrow cells in the tumour macroenvironment to form pre-metastatic niches at distant sites by increasing VEGF secretion from cancer-associated fibroblasts. Cancer cells are then attracted to the metastatic site via the CXCL5/CXCR2 axis. Bone marrow cells transplanted from nude mice bearing Id1-overexpressing oesophageal tumours enhance tumour growth and metastasis in recipient mice, whereas systemic administration of VEGFR1 antibody abrogates these effects. Mechanistically, IGF2 regulates VEGF in fibroblasts via miR-29c in a p53-dependent manner. Analysis of patient serum samples showed that concurrent elevation of IGF2 and VEGF levels may serve as a prognostic biomarker for oesophageal cancer. These findings suggest that the Id1/IGF2/VEGF/VEGFR1 cascade plays a critical role in tumour-driven pathophysiological processes underlying cancer progression.

The Id-protein family in developmental and cancer-associated pathways

Inhibitors of DNA binding and cell differentiation (Id) proteins are members of the large family of the helix-loop-helix (HLH) transcription factors, but they lack any DNA-binding motif. During development, the Id proteins play a key role in the regulation of cell-cycle progression and cell differentiation by modulating different cell-cycle regulators both by direct and indirect mechanisms. Several Id-protein interacting partners have been identified thus far, which belong to structurally and functionally unrelated families, including, among others, the class I and II bHLH transcription factors, the retinoblastoma protein and related pocket proteins, the paired-box transcription factors, and the S5a subunit of the 26 S proteasome. Although the HLH domain of the Id proteins is involved in most of their protein-protein interaction events, additional motifs located in their N-terminal and C-terminal regions are required for the recognition of diverse protein partners. The ability of the Id proteins to interact with structurally different proteins is likely to arise from their conformational flexibility: indeed, these proteins contain intrinsically disordered regions that, in the case of the HLH region, undergo folding upon self- or heteroassociation. Besides their crucial role for cell-fate determination and cell-cycle progression during development, other important cellular events have been related to the Id-protein expression in a number of pathologies. Dysregulated Id-protein expression has been associated with tumor growth, vascularization, invasiveness, metastasis, chemoresistance and stemness, as well as with various developmental defects and diseases. Herein we provide an overview on the structural properties, mode of action, biological function and therapeutic potential of these regulatory proteins.

The Id-protein family in developmental and cancer-associated pathways

Inhibitors of DNA binding and cell differentiation (Id) proteins are members of the large family of the helix-loop-helix (HLH) transcription factors, but they lack any DNA-binding motif. During development, the Id proteins play a key role in the regulation of cell-cycle progression and cell differentiation by modulating different cell-cycle regulators both by direct and indirect mechanisms. Several Id-protein interacting partners have been identified thus far, which belong to structurally and functionally unrelated families, including, among others, the class I and II bHLH transcription factors, the retinoblastoma protein and related pocket proteins, the paired-box transcription factors, and the S5a subunit of the 26 S proteasome. Although the HLH domain of the Id proteins is involved in most of their protein-protein interaction events, additional motifs located in their N-terminal and C-terminal regions are required for the recognition of diverse protein partners. The ability of the Id proteins to interact with structurally different proteins is likely to arise from their conformational flexibility: indeed, these proteins contain intrinsically disordered regions that, in the case of the HLH region, undergo folding upon self- or heteroassociation. Besides their crucial role for cell-fate determination and cell-cycle progression during development, other important cellular events have been related to the Id-protein expression in a number of pathologies. Dysregulated Id-protein expression has been associated with tumor growth, vascularization, invasiveness, metastasis, chemoresistance and stemness, as well as with various developmental defects and diseases. Herein we provide an overview on the structural properties, mode of action, biological function and therapeutic potential of these regulatory proteins.

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.

Id Proteins Contribute to Tumor Development and Metastatic Colonization in a Model of Bladder Carcinogenesis

Background: Bladder cancer is one of the most common malignant genitourinary diseases worldwide. Despite advances in surgical technique, medical oncology and radiation therapy, cure of invasive tumors remains elusive for patients with late stage disease. Therefore, new therapeutic strategies are needed to improve the response rates with regard to recurrence, invasion and metastasis.

Objective: Inhibitor of DNA binding (Id) proteins have been proposed as therapeutic targets due to the key regulatory role they exert in multiple steps of cancer. We aimed to explore the role of Id proteins in bladder cancer development and the pattern of expression of Id proteins in bladder carcinomas.

Methods: We used a well-established chemically induced model of bladder carcinogenesis. Wild type and Id-deficient mice were given N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) in the drinking water and urinary bladder lesions were analyzed histopathologically and stained for Id1. We assessed the effects of Id1 inactivation in cultured bladder cancer cells and in a model of metastatic lung colonization. We also performed Id1 staining of human urothelial carcinoma samples and matched lymph node metastases.

Results: Id1 protein was overexpressed in the BBN-induced model of bladder cancer. Id1 deficiency resulted in the development of urinary bladder tumors with areas of extensive hemorrhage and decreased invasiveness when compared to wild type mice. Id1 inactivation led to decreased cell growth in vitro and lung colonization in vivo of human bladder cancer cells. Immunohistochemistry performed on human urothelial carcinoma samples showed Id1 positive staining in both primary tumors and lymph node metastases.

Conclusions: In summary, our studies reveal the physiological relevance of Id1 in bladder cancer progression and suggest that targeting Id1 may be important in the development of novel therapies for the treatment of bladder cancer.

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.

Inhibitor of differentiation 4 (ID4) acts as an inhibitor of ID-1, -2 and -3 and promotes basic helix loop helix (bHLH) E47 DNA binding and transcriptional activity

The four known ID proteins (ID1-4, Inhibitor of Differentiation) share a homologous helix loop helix (HLH) domain and act as dominant negative regulators of basic-HLH transcription factors. ID proteins also interact with many non-bHLH proteins in complex networks. The expression of ID proteins is increasingly observed in many cancers. Whereas ID-1, ID-2 and ID-3, are generally considered as tumor promoters, ID4 on the contrary has emerged as a tumor suppressor. In this study we demonstrate that ID4 heterodimerizes with ID-1, -2 and -3 and promote bHLH DNA binding, essentially acting as an inhibitor of inhibitors of differentiation proteins. Interaction of ID4 was observed with ID1, ID2 and ID3 that was dependent on intact HLH domain of ID4. Interaction with bHLH protein E47 required almost 3 fold higher concentration of ID4 as compared to ID1. Furthermore, inhibition of E47 DNA binding by ID1 was restored by ID4 in an EMSA binding assay. ID4 and ID1 were also colocalized in prostate cancer cell line LNCaP. The alpha helix forming alanine stretch N-terminal, unique to HLH ID4 domain was required for optimum interaction. Ectopic expression of ID4 in DU145 prostate cancer line promoted E47 dependent expression of CDKNI p21. Thus counteracting the biological activities of ID-1, -2 and -3 by forming inactive heterodimers appears to be a novel mechanism of action of ID4. These results could have far reaching consequences in developing strategies to target ID proteins for cancer therapy and understanding biologically relevant ID-interactions.

ERβ1 inhibits the migration and invasion of breast cancer cells through upregulation of E-cadherin in a Id1-dependent manner

ERβ1 is a member of the nuclear receptor superfamily of ligand-regulated transcription factors. It plays an important role in regulating the progression of breast cancer. However, the mechanisms of ERβ1 in tumorigenesis, metastasis and prognosis are still not fully clear. In this study, we showed that the expression of ERβ1 was positively correlated with E-cadherin expression in breast cancer cell lines. In addition, we found that ERβ1 upregulates E-cadherin expression in breast cancer cell lines. Furthermore, we also found that ERβ1 inhibits the migration and invasion of breast cancer cells and upregulated E-cadherin expression in a Id1-dependent manner. Taken together, our study provides further understanding of the molecular mechanism of ERβ1 in tumor metastasis and suggests the feasibility of developing novel therapeutic approaches to target Id1 to inhibit breast cancer metastasis.

The inhibitor of differentiation isoform Id1b, generated by alternative splicing, maintains cell quiescence and confers self-renewal and cancer stem cell-like properties

Id1 has been shown to play a critical role in tumorigenesis and angiogenesis. Moreover, recent reports have involved Id1 in the maintenance of cancer stem cell features in some tumor types. The Id1 gene generates two isoforms through alternative splicing: Id1a and Id1b. We have investigated the role of each isoform in cancer development. Using lentiviral systems we modified the endogenous expression of each of these isoforms in cancer cells and analyzed their biological effect both in vitro and in vivo. Overexpression of Id1b in murine CT26 and 3LL cells caused a G0/G1 cell cycle arrest and reduced proliferation, clonogenicity and phospho-ERK1/2 levels, while increasing p27 levels. High levels of Id1a had an opposite effect and the proportion of cells in the S phase increased significantly. In vivo models confirmed the inhibitory role of Id1b in primary tumor growth and metastasis. Through microarray analysis we found that the cancer stem cell (CSC) markers ALDH1A1 and Notch-1 were up-regulated specifically in Id1b-overexpressing cells. By using qPCR we also found overexpression of Sca-1, Tert, Sox-2 and Oct-4 in these cells. Increased levels of Id1b promoted self-renewal and CSC-like properties, as shown by their high capacity for developing secondary tumorspheres and retaining the PKH26 dye. The acquisition of CSC phenotype was confirmed in human PC-3 cells that overexpressed Id1b. Our results show that Id1b maintains cells in a quiescent state and promotes self-renewal and CSC-like features. On the contrary, Id1a promotes cell proliferation.

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.

ID1 promotes breast cancer metastasis by S100A9 regulation

Metastasis is a major factor responsible for mortality in patients with breast cancer. Inhibitor of DNA binding 1 (Id1) has been shown to play an important role in cell differentiation, tumor angiogenesis, cell invasion, and metastasis. Despite the data establishing Id1 as a critical factor for lung metastasis in breast cancer, the pathways and molecular mechanisms of Id1 functions in metastasis remain to be defined. Here, we show that Id1 interacts with TFAP2A to suppress S100A9 expression. We show that expression of Id1 and S100A9 is inversely correlated in both breast cancer cell lines and clinical samples. We also show that the migratory and invasive phenotypes in vitro and metastasis in vivo induced by Id1 expression are rescued by reestablishment of S100A9 expression. S100A9 also suppresses the expression of known metastasis-promoting factor RhoC activated by Id1 expression. Our results suggest that Id1 promotes breast cancer metastasis by the suppression of S100A9 expression.

IMPLICATIONS

Novel pathways by Id1 regulation in metastasis.

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.

New insights into the role of ID proteins in breast cancer metastasis: a MET affair

The establishment of lethal metastases depends on the capacity of a small number of cancer cells to regenerate a tumor after entering a target organ. Stankic and colleagues have identified a role for the inhibitor of differentiation protein, ID1, as a critical regulator of breast cancer stem-like properties and metastatic colonization. Under the control of tumor growth factor-beta signaling, ID1 induces mesenchymal-epithelial transition at the metastatic site by antagonizing the activity of the basic helix-loop-helix transcription factor Twist1. This study sheds light on mechanisms that initiate metastatic outgrowth, and strengthens the concept that epithelial-mesenchymal plasticity is crucial at different stages of metastasis.

Inhibitors of differentiation-1 promotes nitrosopyrrolidine-induced transformation of HPV 16-immortalized cervical epithelial cell

Our previous study implied a correlation between inhibitors of differentiation-1 (Id-1) and cervical cancer development. However, how Id-1 contributes to cervical carcinogenesis is unknown. In the present study, we used an in vitro transformation model to investigate the role of Id-1 in the transformation of cervical cells. Human papillomavirus (HPV)-immortalized cervical epithelial cells (H8) were successfully transformed by exposure to the carcinogen N-nitrosopyrrolidine (NPYR). The expression of both Id-1 RNA and protein was significantly increased in transformed H8 cells, suggesting a possible role of Id-1 in cervical cell transformation. Ectopic expression of Id-1 in H8 cells potentiated NPYR-induced cell transformation. In contrast, silencing of Id-1 suppressed NPYR-induced H8 cell transformation. In addition, the expression of HPV E6 and E7 oncoproteins was upregulated while that of the tumor suppressors p53 and pRb was suppressed after H8 cell transformation. Our results suggest that Id-1 plays an oncogenic role in HPV-related cervical carcinogenesis, which sheds light on cervical cancer development mechanisms and implies that Id-1 is a potential target for cervical cancer prevention and therapy.

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.

Correlation between the expression of Id-1 and hyperthermia-associated molecules in oral squamous cell carcinoma

OBJECTIVE

To investigate the expression of inhibitor of differentiation/DNA binding (Id-1), phosphatidylinositol-3-kinase/protein kinase B pathway proteins and hyperthermia-associated protein and their association with various clinicopathological factors in oral squamous cell cancer (OSCC), and explore the relationship among them in OSCC.

METHODS

Id-1, phosphorylated protein kinase B (p-Akt), phosphorylated glycogen synthase kinase 3β (p-GSK3β) and phosphorylated heat shock factor 1 (p-HSF1) expression were assessed immunohistochemically in 76 OSCC.

RESULTS

Id-1 (73.8%), p-Akt (65.8%), p-GSK3β (60.5%) and p-HSF1 (75%) were found to be overexpressed in most of the oral cancer samples tested, and the expressions of them are correlated with advanced clinical stage, metastasis and recurrence (p<0.01), but there is no apparent relationship with gender, age, differentiation and habits (p>0.05). Survival curves show that the survival of patients with high Id-1, p-Akt, p-GSK3β and p-HSF1 expression was significantly worse than those with low Id-1, p-Akt, p-GSK3β and p-HSF1 expression (p=0.000). Id-1 expression was significantly higher in cases with high expression of p-Akt, p-GSK3β and p-HSF1 than in those with low expression (p=0.002, p=0.003, p=0.001).

CONCLUSIONS

This study revealed that there was a positive correlation between Id-1 expression and the expression of p-Akt, p-GSK3β and p-HSF1. The inhibition of Id-1 expression can improve the efficacy of hyperthermia in OSCC.

Id-1 is a key transcriptional regulator of glioblastoma aggressiveness and a novel therapeutic target

Glioblastoma is the most common form of primary adult brain tumors. A majority of glioblastomas grow invasively into distant brain tissue, leading to tumor recurrence, which is ultimately incurable. It is, therefore, essential to discover master regulators that control glioblastoma invasiveness and target them therapeutically. We show here that the transcriptional regulator Id-1 plays a critical role in modulating the invasiveness of glioblastoma cell lines and primary glioblastoma cells. Id-1 expression levels positively correlate with glioma cell invasiveness in culture and with histopathologic grades in patient biopsies. Id-1 knockdown dramatically reduces glioblastoma cell invasion that is accompanied by profound morphologic changes and robust reduction in expression levels of "mesenchymal" markers, as well as inhibition of self-renewal potential and downregulation of glioma stem cell markers. Importantly, genetic knockdown of Id-1 leads to a significant increase in survival in an orthotopic model of human glioblastoma. Furthermore, we show that a nontoxic compound, cannabidiol, significantly downregulates Id-1 gene expression and associated glioma cell invasiveness and self-renewal. In addition, cannabidiol significantly inhibits the invasion of glioblastoma cells through an organotypic brain slice and glioma progression in vivo. Our results suggest that Id-1 regulates multiple tumor-promoting pathways in glioblastoma and that drugs targeting Id-1 represent a novel and promising strategy for improving the therapy and outcome of patients with glioblastoma.

Hypoxic conditions induce a cancer-like phenotype in human breast epithelial cells

INTRODUCTION

Solid tumors are less oxygenated than their tissue of origin. Low intra-tumor oxygen levels are associated with worse outcome, increased metastatic potential and immature phenotype in breast cancer. We have reported that tumor hypoxia correlates to low differentiation status in breast cancer. Less is known about effects of hypoxia on non-malignant cells. Here we address whether hypoxia influences the differentiation stage of non-malignant breast epithelial cells and potentially have bearing on early stages of tumorigenesis.

METHODS

Normal human primary breast epithelial cells and immortalized non-malignant mammary epithelial MCF-10A cells were grown in a three-dimensional overlay culture on laminin-rich extracellular matrix for up to 21 days at normoxic or hypoxic conditions. Acinar morphogenesis and expression of markers of epithelial differentiation and cell polarization were analyzed by immunofluorescence, immunohistochemistry, qPCR and immunoblot.

RESULTS

In large ductal carcinoma in situ patient-specimens, we find that epithelial cells with high HIF-1α levels and multiple cell layers away from the vasculature are immature compared to well-oxygenated cells. We show that hypoxic conditions impaired acinar morphogenesis of primary and immortalized breast epithelial cells grown ex vivo on laminin-rich matrix. Normoxic cultures formed polarized acini-like spheres with the anticipated distribution of marker proteins associated with mammary epithelial polarization e.g. α6-integrin, laminin 5 and Human Milk Fat Globule/MUC1. At hypoxia, cells were not polarized and the sub-cellular distribution pattern of the marker proteins rather resembled that reported in vivo in breast cancer. The hypoxic cells remained in a mitotic state, whereas proliferation ceased with acinar morphogenesis at normoxia. We found induced expression of the differentiation repressor ID1 in the undifferentiated hypoxic MCF-10A cell structures. Acinar morphogenesis was associated with global histone deacetylation whereas the hypoxic breast epithelial cells showed sustained global histone acetylation, which is generally associated with active transcription and an undifferentiated proliferative state.

Id1 and Id3 expression is associated with increasing grade of prostate cancer: Id3 preferentially regulates CDKN1B

As transcriptional regulators of basic helix-oop-helix (bHLH) transcription and non-bHLH factors, the inhibitor of differentiation (Id1, Id2, Id3, and Id4) proteins play a critical role in coordinated regulation of cell growth, differentiation, tumorigenesis, and angiogenesis. Id1 regulates prostate cancer (PCa) cell proliferation, apoptosis, and androgen independence, but its clinical significance in PCa remains controversial. Moreover, there is lack of evidence on the expression of Id2 and Id3 in PCa progression. In this study we investigated the expression of Id2 and Id3 and reevaluated the expression of Id1 in PCa. We show that increased Id1 and Id3 protein expression is strongly associated with increasing grade of PCa. At the molecular level, we report that silencing either Id1 or Id3 attenuates cell cycle. Although structurally and mechanistically similar, our results show that both these proteins are noncompensatory at least in PCa progression. Moreover, through gene silencing approaches we show that Id1 and Id3 primarily attenuates CDKN1A (p21) and CDKN1B (p27), respectively. We also demonstrate that silencing Id3 alone significantly attenuates proliferation of PCa cells as compared with Id1. We propose that increased Id1 and Id3 expression attenuates all three cyclin-dependent kinase inhibitors (CDKN2B, -1A, and -1B) resulting in a more aggressive PCa phenotype.

Epigenetic inactivation of inhibitor of differentiation 4 (Id4) correlates with prostate cancer

The inhibitor of DNA-binding (Id) proteins, Id1–4 are negative regulators of basic helix-loop-helix (bHLH) transcription factors. As key regulators of cell cycle and differentiation, expression of Id proteins are increasingly observed in many cancers and associated with aggressiveness of the disease. Of all the four Id proteins, the expression of Id1, Id2, and to a lesser extent, Id3 in prostate cancer and the underlying molecular mechanism is relatively well known. On the contrary, our previous results demonstrated that Id4 acts as a potential tumor suppressor in prostate cancer. In the present study, we extend these observations and demonstrate that Id4 is down-regulated in prostate cancer due to promoter hypermethylation. We used prostate cancer tissue microarrays to investigate Id4 expression. Methylation specific PCR on bisulfite treated DNA was used to determine methylation status of Id4 promoter in laser capture micro-dissected normal, stroma and prostate cancer regions. High Id4 expression was observed in the normal prostate epithelial cells. In prostate cancer, a stage-dependent decrease in Id4 expression was observed with majority of high grade cancers showing no Id4 expression. Furthermore, Id4 expression progressively decreased in prostate cancer cell line LNCaP and with no expression in androgen-insensitive LNCaP-C81 cell line. Conversely, Id4 promoter hypermethylation increased in LNCaP-C81 cells suggesting epigenetic silencing. In prostate cancer samples, loss of Id4 expression was also associated with promoter hypermethylation. Our results demonstrate loss of Id4 expression in prostate cancer due to promoter hypermethylation. The data strongly support the role of Id4 as a tumor suppressor.

Physical and functional interaction between the ID1 and p65 for activation of NF-κB

Inhibitor of differentiation or DNA binding-1 (ID1) is an important helix-loop-helix (HLH) transcription factor involved in diverse biological functions including cell differentiation, proliferation, apoptosis, and senescence. Recently, it was reported that ID1 can activate the NF-κB signaling pathway in a variety of cancer cells and a T cell line, but the mechanisms involved in ID1-mediated transactivation of NF-κB are not clear. In this study, we demonstrate by both in vitro pull-down assays and a cell-based in vivo two-hybrid system that ID1-mediated NF-κB activation is due to its physical interaction with p65. We have identified that the transcriptional activation domain (TAD) in p65 and the HLH domain in ID1 are vital for their interaction. Interestingly, a single site mutation (Leu76) in the HLH domain of ID1 protein drastically decreased its ability to bind with p65. Using a dual-luciferase assay, we demonstrated that the interaction between ID1 and p65 modulates activation of the NF-κB signaling pathway in vivo. In addition, we demonstrated that, by affecting the nuclear translocation of p65, ID1 is essential in regulating TNF-α-induced p65 recruitment to its downstream target, the cellular inhibitor of apoptosis protein 2 (cIAP2) promoter.

Genome wide DNA copy number analysis of serous type ovarian carcinomas identifies genetic markers predictive of clinical outcome

Ovarian cancer is the fifth leading cause of cancer death in women. Ovarian cancers display a high degree of complex genetic alterations involving many oncogenes and tumor suppressor genes. Analysis of the association between genetic alterations and clinical endpoints such as survival will lead to improved patient management via genetic stratification of patients into clinically relevant subgroups. In this study, we aim to define subgroups of high-grade serous ovarian carcinomas that differ with respect to prognosis and overall survival. Genome-wide DNA copy number alterations (CNAs) were measured in 72 clinically annotated, high-grade serous tumors using high-resolution oligonucleotide arrays. Two clinically annotated, independent cohorts were used for validation. Unsupervised hierarchical clustering of copy number data derived from the 72 patient cohort resulted in two clusters with significant difference in progression free survival (PFS) and a marginal difference in overall survival (OS). GISTIC analysis of the two clusters identified altered regions unique to each cluster. Supervised clustering of two independent large cohorts of high-grade serous tumors using the classification scheme derived from the two initial clusters validated our results and identified 8 genomic regions that are distinctly different among the subgroups. These 8 regions map to 8p21.3, 8p23.2, 12p12.1, 17p11.2, 17p12, 19q12, 20q11.21 and 20q13.12; and harbor potential oncogenes and tumor suppressor genes that are likely to be involved in the pathogenesis of ovarian carcinoma. We have identified a set of genetic alterations that could be used for stratification of high-grade serous tumors into clinically relevant treatment subgroups.

Id-1 and the p65 subunit of NF-κB promote migration of nasopharyngeal carcinoma cells and are correlated with poor prognosis

Inhibitor of differentiation (Id)-1 and nuclear factor-kappa B (NF-κB) have been detected in many malignant tumors, and their presence has been correlated with the metastatic potential of these tumors. This study was undertaken to investigate the prognostic significance of the expression of Id-1 and the p65 subunit of NF-κB (NF-κB/p65) and the proteins' roles in the invasion process of nasopharyngeal carcinoma (NPC) cells. The messenger RNA (mRNA) and protein levels of Id-1 and NF-κB/p65 in normal nasopharyngeal epithelial cells and NPC cell lines were examined using reverse transcription-PCR and western blot analysis, whereas the mRNA and protein levels of Id-1 and NF-κB/p65 in clinical NPC specimens were determined by reverse transcription-PCR and immunohistochemistry. Short hairpin RNA (shRNA) was used to silence Id-1 and NF-κB/p65 to allow for the examination of matrix metalloproteinase (MMP)-9 expression and migratory capacity changes in CNE-2 cells. Multivariate Cox analysis revealed that elevated Id-1 expression was a significant independent predictor of the 5 year overall survival rate (hazards ratio = 16.720, P = 0.005). Furthermore, elevated expression of both Id-1 and NF-κB/p65 was associated with poor clinical survival (P = 0.049). Targeting Id-1 and NF-κB/p65 mRNA with shRNA in CNE-2 cells inhibited MMP-9 expression and decreased the migratory capacity of CNE-2 cells. In conclusion, Id-1 expression is a novel independent prognostic marker molecule that helps identify NPC patients with a poor prognosis. Additionally, combined analysis of Id-1 and NF-κB/p65 can be useful for identifying patients at risk for unfavorable clinical outcomes. Id-1 or/and NF-κB/p65 enhanced tumor cell migration, which is associated with the secretion of MMP-9.

Prognostic implications of genetic aberrations in acute myelogenous leukemia with normal cytogenetics

Acute myelogenous leukemia (AML) is a genetically heterogeneous disease in which somatic mutations, that disturb cellular growth, proliferation, and differentiation, accumulate in hematopoietic progenitor cells. Cytogenetic findings, at diagnosis, have been proven to be one of the most important prognostic indicators in AML. About half of the patients with AML are found to have "normal" cytogenetic analysis by standard culture techniques. These patients are considered as an intermediate risk group. Cytogenetically normal AML (CN-AML) is the largest cytogenetic risk group, and the variation in clinical outcome of patients in this group is greater than in any other cytogenetic group. Besides mutation testing, age and presenting white blood cell count are important predictors of overall survival, suggesting that other factors independent of cytogenetic abnormalities, contribute to the outcome of patients with AML. The expanding knowledge at the genetic and molecular levels is helping define several subgroups of patients with CN-AML with variable prognosis. In this review, we describe the clinical and prognostic characteristics of CN-AML patients as a group, as well as the various molecular and genetic aberrations detected in these patients and their clinical and prognostic implications.

Id-1 induces cell invasiveness in immortalized epithelial cells by regulating cadherin switching and Rho GTPases

Epithelial-mesenchymal transition (EMT), characterized by cadherin switching, contributes to cancer metastasis. Our recent study showed that Id-1 (inhibitor of differentiation-1) promotes metastasis in esophageal cancer cells, but whether the invasive and metastatic dynamics can be induced early in the carcinogenesis process is still unclear. Immortalization is regarded as the initial stage in the malignant transformation of normal cells. In this study, we investigated the role and mechanisms of Id-1 in inducing EMT and cell invasiveness in immortalized esophageal epithelial cells. We found that immortalized epithelial cells expressed higher endogenous levels of Id-1 compared with normal cells. Ectopic Id-1 expression inhibited the differentiation of immortalized esophageal epithelial cells and promoted cadherin switching, which was accompanied by increased adhesiveness to extracellular matrix, cell motility, migratory potential and matrix metalloproteinase-dependent invasiveness. GTPase activity assays showed that over-expression or short-hairpin RNA knockdown of Id-1 led to corresponding changes in Rac1 activity, whereas RhoA activity was significantly decreased with Id-1 depletion. Inhibitors targeting Rac1, RhoA, and Rho kinase suppressed the invasiveness of Id-1-expressing NE2-hTERT cells. Knockdown of N-cadherin in Id-1-over-expressing cells inhibited cell invasiveness and down-regulated RhoA activity. These data suggest that the Id-1-induced invasive potential may be regulated through the N-cadherin-RhoA axis and Rac1 activation.

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.

Silencing Id-1 inhibits lymphangiogenesis through down-regulation of VEGF-C in oral squamous cell carcinoma

Our previous study demonstrated that overexpression of Id-1 (inhibitor of differentiation/DNA binding) was associated with lymphatic metastasis in human oral squamous cell carcinoma (OSCC). In this study, we further unveiled the association of Id-1 with vascular endothelial growth factor-C (VEGF-C) and peritumoral lymphatic vessel density (PLVD), and the effect of silencing Id-1 on inhibiting lymphangiogenesis in OSCC. We found that Id-1 was associated with VEGF-C (r=0.569, p<0.001) and PLVD (r=0.240, p<0.001) in OSCC. Lentivirus-mediated RNA interference targeting Id-1 in an OSCC cell line Tca8113 resulted in down-regulation of VEGF-C (p=0.003, 0.007). Moreover, when Id-1 was suppressed by injecting Id-1-siRNA-lentivirus into the transplanted tumors in nude mice, VEGF-C was down-regulated (p=0.018) and the PLVD decreased (p=0.001). Our results suggest that Id-1 was correlated with lymphangiogenesis in OSCC. Silencing Id-1 could inhibit lymphangiogenesis through down-regulation of VEGF-C and it might be a promising treatment modality for the lymphatic metastasis of OSCC.

Nuclear and cytoplasmic Id-1 expression patterns play different roles in angiogenesis and lymphangiogenesis in gastric carcinoma

The purpose of the study was to investigate the expression and impact of Id-1 (inhibitor of differentiation) on tumor progression, angiogenesis, and lymphangiogenesis in gastric adenocarcinoma. The study included 97 cases of gastric adenocarcinoma, which were surgically excised at the Second Hospital of Shandong University. Immunohistochemistry was used to detect the Id-1 expression, and dual-labeling immunohistochemistry was used to evaluate the microvessel density (MVD) and lymphatic vessel density (LVD). The Id-1 protein was mainly expressed with nuclear staining in well-differentiated carcinoma, but with cytoplasmic staining in moderately and poorly differentiated carcinoma, which showed a significant difference (P < .0001). Moreover, the expression patterns had different and crucial effects on angiogenesis and lymphangiogenesis. Nuclear staining of Id-1 inhibited angiogenesis, but cytoplasmic staining promoted angiogenesis (MVD, 110.57 ± 32.32 vs 141.45 ± 55.60) (P < .05). Consistent with their roles in angiogenesis, the nuclear and cytoplasmic expressions of Id-1 had similar effects on lymphangiogenesis: nuclear expression inhibited and cytoplasmic expression promoted lymphangiogenesis (LVD, 2.62 ± 1.03 vs 4.05 ± 2.04) (P < .05). Microvessel density and LVD showed no significant difference in low-and high-Id-1 expression groups (P > .05). Aberrant expression of Id-1 from nuclear to cytoplasm is accompanied with tumor malignant progression, which promotes angiogenesis and lymphangiogenesis; and Id-1 should be developed as a target for gastric carcinoma therapy.