Targeting Id1 reduces proliferation and invasion in aggressive human salivary gland cancer cells

MYB fusions and CD markers as tools for authentication and purification of cancer stem cells from salivary adenoid cystic carcinoma

Cancer stem cells (CSC) are considered the major cause of aggressive tumor behavior, recurrence, metastases, and resistance to radiation, making them an attractive therapeutic target. However, isolation of CSC from tumor tissue and their characterization are challenging due to uncertainty about their molecular markers and conditions for their propagation. Adenoid cystic carcinoma (ACC), which arises predominantly in the salivary glands, is a slow-growing but relentless tumor that frequently invades nerves and metastasizes. New effective treatment approaches for ACC have not emerged over the last 40years. Previously, based on a highly conserved SOX10 gene signature that we identified in the majority of ACC tumors, we suggested the existence in ACC of SOX10+ cells with neural stem properties and corroborated this hypothesis via isolation from ACC tissue a novel population of CSC, termed ACC-CSC. These cells activated NOTCH1 signaling and co-expressed SOX10 and other ACC-intrinsic neural crest stem cell markers with CD133, a CSC cell surface marker, suggesting that ACC is driven by a previously uncharacterized population of SOX10+/CD133+ cells with neural stem cell properties. Here, we authenticated ACC identity of our primary cultures by demonstrating that most of them harbor MYB-NFIB fusions, which are found in 86% of ACC. We demonstrated using CyTOF, a novel mass cytometry technology, that these cells express high β-catenin and STAT3 levels and are marked by CD24 and CD44. Finally, to streamline development of ACC cell lines, we developed RT-PCR tests for distinguishing mouse and human cells and used immunomagnetic cell sorting to eliminate mouse cells from long-term cell cultures. Overall, this study describes a new population of CSC that activates signaling pathways associated with poor prognosis, validates their ACC identity, and optimizes approaches that can be used for purification of ACC-CSC and generation of cell lines.

Targeting ID2 expression triggers a more differentiated phenotype and reduces aggressiveness in human salivary gland cancer cells

Inhibitors of DNA-binding (ID) proteins are negative regulators of basic helix-loop-helix transcription factors and generally stimulate cell proliferation and inhibit differentiation. We previously determined that ID1 was highly expressed in aggressive salivary gland cancer (SGC) cells in culture. Here, we show that ID2 is also expressed in aggressive SGC cells. ID2 knockdown triggers important changes in cell behavior, that is, it significantly reduces the expression of N-cadherin, vimentin and Snail, induces E-cadherin expression and leads to a more differentiated phenotype exemplified by changes in cell shape. Moreover, ID2 knockdown almost completely suppresses invasion and the expression of matrix metalloproteinase 9. In conclusion, ID2 expression maintains an aggressive phenotype in SGC cells, and ID2 repression triggers a reduction in cell aggressiveness. ID2 therefore represents a potential therapeutic target during SGC progression. ID proteins are negative regulators of basic helix-loop-helix transcription factors and generally stimulate cell proliferation and inhibit differentiation. ID2 knockdown triggers important changes in cell behavior, that is, it significantly reduces the expression of N-cadherin, vimentin and Snail, induces E-cadherin expression and leads to a more differentiated phenotype exemplified by changes in cell shape. ID2 therefore represents a potential therapeutic target during SGC progression.

Suppression of invasion and metastasis in aggressive salivary cancer cells through targeted inhibition of ID1 gene expression

Salivary gland cancer (SGC) represents the most common malignancy in the head and neck region, and often metastasizes to the lungs. The helix-loop-helix ID1 protein has been shown to control metastatic progression in many types of cancers. Using two different approaches to target the expression of ID1 (genetic knockdown and progesterone receptor introduction combined with progesterone treatment), we previously determined that the aggressiveness of salivary gland tumor ACCM cells in culture was suppressed. Here, using the same approaches to target ID1 expression, we investigated the ability of ACCM cells to generate lung metastatic foci in nude mice. Moreover, since both approaches would be challenging for applications in humans, we added a third approach, i.e., treatment of mice with a non-toxic cannabinoid compound known to down-regulate ID1 gene expression. All approaches aimed at targeting the pro-metastatic ID1 gene led to a significant reduction in the formation of lung metastatic foci. Therefore, targeting a key transcriptional regulator using different means results in the same reduction of the metastatic spread of SGC cells in animal models, suggesting a novel approach for the treatment of patients with aggressive SGC.

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.

Insulin-like growth factor--phosphatidylinositol 3 kinase signaling in canine cortisol-secreting adrenocortical tumors

Background

Hypercortisolism is a common endocrine disorder in dogs, caused by a cortisol‐secreting adrenocortical tumor (AT) in approximately 15% of cases. In adrenocortical carcinomas of humans, activation of the phosphatidylinositol 3 kinase (PI3K) signaling pathway by insulin‐like growth factor (IGF) signaling represents a promising therapeutic target.

Objectives

To investigate the involvement of PI3K signaling in the pathogenesis of ATs in dogs and to identify pathway components that may hold promise as future therapeutic targets or as prognostic markers.

Animals

Analyses were performed on 36 canine cortisol‐secreting ATs (11 adenomas and 25 carcinomas) and 15 normal adrenal glands of dogs.

Methods

mRNA expression analysis was performed for PI3K target genes, PI3K inhibitor phosphatase and tensin homolog (PTEN), IGFs, IGF receptors, IGF binding proteins and epidermal growth factor receptors. Mutation analysis was performed on genes encoding PTEN and PI3K catalytic subunit (PIK3CA).

Results

Target gene expression indicated PI3K activation in carcinomas, but not in adenomas. No amino acid‐changing mutations were detected in PTEN or PIK3CA and no significant alterations in IGF‐II or IGFR1 expression were detected. In carcinomas, ERBB2 expression tended to be higher than in normal adrenal glands, and higher expression of inhibitor of differentiation 1 and 2 (ID1 and ID2) was detected in carcinomas with recurrence within 2.5 years after adrenalectomy.

Conclusions and Clinical Importance

Based on these results, ERBB2 might be a promising therapeutic target in ATs in dogs, whereas ID1 and 2 might be valuable as prognostic markers and therapeutic targets.

TGF-β1-induced expression of Id-1 is associated with tumor progression in gastric cancer

Transforming growth factor β1 (TGF-β1) and inhibitor of differentiation/DNA-binding 1 (Id-1) have been shown to be associated with aggressive metastatic behavior of cancer cells in many malignant tumors. However, their role in gastric cancer (GC) has not been established. In this study, we investigated the relationship between expression of Id-1 and TGF-β1 in GC as well as their association with GC progression. The immunohistochemical analysis of 71 human GC samples indicated that both Id-1 and TGF-β1 were markedly upregulated in tumor tissue compared with the adjacent tissue; in addition, a significant positive correlation was found between the expression levels of Id-1 and TGF-β1 by Pearson's correlation analysis. Furthermore, the investigation of the association of Id-1 and TGF-β1 with patient clinical characteristics revealed that Id-1 expression was significantly correlated with tumor differentiation, while TGF-β1 was associated with lymph node metastasis. The results were validated in vitro by using a GC cell line, AGS. The expression of Id-1 was upregulated at 24 and 48 h after the treatment with TGF-β1, whereas it did not affect the proliferation of cells. TGF-β1 also influenced the expression of N-cadherin and β-catenin. Our results suggested that Id-1 and TGF-β1 played important roles in the progression of GC, in which Id-1 might act as a downstream mediator of TGF-β1 signaling through a regulatory mechanism involving N-cadherin and β-catenin. The TGF-β1/Id-1 axis might serve as a future therapeutic target for GC.

Inhibitor of DNA-binding protein 1 knockdown arrests the growth of colorectal cancer cells and suppresses hepatic metastasis in vivo

Inhibitor of DNA-binding protein 1 (ID1) is commonly abnormally overexpressed in colorectal cancer (CRC); yet, the functional significance of ID1 in the growth and invasive properties of CRC cells remains largely unclear. The present study investigated the effects of ID1 downregulation on the cell growth and metastatic features of CRC. Using lentiviral shRNA infection, stable ID1-knockdown (KD) HCT116 and SW620 cells, human metastatic CRC cell lines, were created. In vitro, the migration/invasion capacity of the ID1-KD CRC cells was assessed by a wound healing assay. The activities of MMP2 and MMP-9 were measured by gelatin zymography. The expression of CXC chemokine receptor 4 (CXCR4), PCNA and survivin were determined by immunoblot analysis and qRT-PCR. The effects of ID1 knockdown on tumor growth and hepatic metastasis were demonstrated by a xenograft study in mice. The results showed evident decreases in proliferation, migration and invasion and an increased apoptosis rate in the ID1-KD CRC cells. Similarly, ID1 knockdown significantly decreased mRNA and protein levels of PCNA, survivin, CXCR4, MMP2 and MMP9. Overexpression of CXCR4 antagonized the negative effect on the migration and invasion abilities of the ID1-KD cells. As compared with the control, ID1 knockdown prevented tumor growth and profoundly suppressed hepatic metastasis in vivo. The present study demonstrated the significance of ID1 in colon cancer progression, and its effect on tumor invasiveness and metastatic properties may be partly dependent on CXCR4.

A review: Immunological markers for malignant salivary gland tumors

Salivary gland cancers are rare. Around 8 out of 10 salivary gland tumors (80%) are in the parotid. Just fewer than 2 out of 10 salivary gland cancers develop in the other two salivary glands - the submandibular or sublingual glands. Fewer than 1 in 10 cancers start in the minor salivary glands. There are many different types of salivary gland cancers. The most common is mucoepidermoid carcinoma (MEC). Just over 3 out of 10 (25-35%) salivary gland cancers (SGT, SGC) are of this type. The others include adenoid cystic carcinoma (ACC), acinic cell carcinoma, carcinoma ex-pleomorphic adenoma (Ca-PA), polymorphous low grade adenocarcinoma (PLGA) and some newly discovered salivary gland tumors. Because of the infrequency of salivary gland tumors and their complex histopathological diagnosis, it is difficult to exactly predict their clinical course by means of its recurrence, malignant progression or metastasis. Salivary gland tumors always pose problems in diagnosis. This review provides an insight into the recent concepts and immunohistochemical markers to diagnose the malignant salivary gland tumors (SGT), thus guiding the Ear, Nose and Throat specialists, Oral and Maxillofacial Surgeons, General Pathologists and other medical and dental specialists thereby enabling them to make correct diagnosis and provide the appropriate treatment.

Overexpression of EMMPRIN isoform 2 is associated with head and neck cancer metastasis

Extracellular matrix metalloproteinase inducer (EMMPRIN), a plasma membrane protein of the immunoglobulin (Ig) superfamily, has been reported to promote cancer cell invasion and metastasis in several human malignancies. However, the roles of the different EMMPRIN isoforms and their associated mechanisms in head and neck cancer progression remain unknown. Using quantitative real-time PCR, we found that EMMPRIN isoform 2 (EMMPRIN-2) was the only isoform that was overexpressed in both head and neck cancer tissues and cell lines and that it was associated with head and neck cancer metastasis. To determine the effects of EMMPRIN-2 on head and neck cancer progression, we transfected head and neck cancer cells with an EMMPRIN-2 expression vector and EMMPRIN-2 siRNA to exogenously modulate EMMPRIN-2 expression and examined the functional importance of EMMPRIN-2 in head and neck cancer invasion and metastasis. We found that EMMPRIN-2 promoted head and neck cancer cell invasion, migration, and adhesion in vitro and increased lung metastasis in vivo. Mechanistic studies revealed that EMMPRIN-2 overexpression promoted the secretion of extracellular signaling molecules, including matrix metalloproteinases-2(MMP-2), urokinase-type plasminogen activator(uPA) and Cathepsin B, in head and neck cancer cells. While MMP-2 and uPA have been demonstrated to be important mediators of EMMPRIN signaling, the role of Cathepsin B in EMMPRIN-mediated molecular cascades and tumorigenesis has not been established. We found that EMMPRIN-2 overexpression and Cathepsin B down-regulation significantly inhibited the invasion, migration and adhesion of Tca8133 cells, suggesting that Cathepsin B is required for EMMPRIN-2 enhanced cell migration and invasion in head and neck cancer. The results of our study demonstrate the important role of EMMPRIN-2 in head and neck cancer progression for the first time and reveal that increased extracellular secretion of Cathepsin B may be a novel mechanism underlying EMMPRIN-2 enhanced tumor progression in head and neck cancer.

Serum regulation of Id1 expression by a BMP pathway and BMP responsive element

Immediate early genes (IEGs) are expressed upon re-entry of quiescent cells into the cell cycle following serum stimulation. These genes are involved in growth control and differentiation and hence their expression is tightly controlled. Many IEGs are regulated through Serum Response Elements (SREs) in their promoters, which bind Serum Response Factor (SRF). However, many other IEGs do not have SREs in their promoters and their serum regulation is poorly understood. We have identified SRF-independent IEGs in SRF-depleted fibroblasts. One of these, Id1, was examined more closely. We mapped a serum responsive element in the Id1 promoter and find that it is identical to a BMP responsive element (BRE). The Id1 BRE is necessary and sufficient for the serum regulation of Id1. Inhibition of the BMP pathway by siRNA depletion of Smad 4, treatment with the BMP antagonist noggin, or the BMP receptor inhibitor dorsomorphin blocked serum induction of Id1. Further, BMP2 is sufficient to induce Id1 expression. Given reports that SRC inhibitors can block Id1 expression, we tested the SRC inhibitor, AZD0530, and found that it inhibits the serum activation of Id1. Surprisingly, this inhibition is independent of SRC or its family members. Rather, we show that AZD0530 directly inhibits the BMP type I receptors. Serum induction of the Id1 related gene Id3 also required the BMP pathway. Given these and other findings we conclude that the Id family of IEGs is regulated by BMPs in serum through similar BREs. This represents a second pathway for serum regulation of IEGs.