Regulation of ß-Catenin Phosphorylation by PR55ß in Adenoid Cystic Carcinoma.

BACKGROUND/AIM: Adenoid cystic carcinoma (AdCC) is a rare cancer of the salivary gland with high risk of recurrence and metastasis. Wnt signalling is critical for determining tumor grade in AdCC, as it regulates invasion and migration. ß-catenin dephosphorylation plays an important role in the Wnt pathway, but its underlying molecular mechanism remains unclear. MATERIALS AND METHODS: Because the regulatory subunits of protein phosphatase 2A (PP2A) drive Wnt signalling via target molecules, including ß-catenin, we used qRT-PCR and immunoblot analysis to investigate the expression of these subunits in an AdCC cell line (ACCS) and a more aggressive subline (ACCS-M). RESULTS: PR55ß was highly expressed in ACCS-M, suggesting its functional importance. In addition, PR55ß expression was associated with tumor grade, with ACCS-M exhibiting higher PR55ß levels. More importantly, knockdown of PR55ß in ACCS-M cells significantly reduced invasiveness and metastatic ability. Furthermore, dephosphorylation and total levels of ß-catenin were dependent on PR55ß in ACCS-M. Finally, we confirmed a correlation between PR55ß staining intensity and histopathological type in human AdCC tissues. CONCLUSION: Our study provides new insight into the interaction between PR55ß and ß-catenin and suggests that PR55ß may be a target for the clinical treatment of AdCC.

Deregulation of Nicotinamide N-Methyltransferase and Gap Junction Protein Alpha-1 Causes Metastasis in Adenoid Cystic Carcinoma.

BACKGROUND/AIM: Adenoid cystic carcinoma (AdCC) is a malignant tumor that occurs in the salivary glands and frequently metastasizes. The aim of this study was to identify factors mediating AdCC metastasis. MATERIALS AND METHODS: We established three AdCC cell lines by orthotropic transplantation and in vivo selection: parental, highly metastatic (ACCS-M-GFP), and lymph node metastatic (ACCS-LN-GFP) cells. RESULTS: We examined the three cell lines. DNA microarray indicated significantly altered processes in ACCS-LN-GFP cells: particularly, the expression of nicotinamide N-methyltransferase (NNMT) was enhanced the most. NNMT is associated with tumorigenesis and is a potential tumor biomarker. Concomitantly, we found-significant down-regulation of gap junction protein alpha-1. We suggest that ACCS-LN-GFP cells acquire cancer stem cell features involving the up-regulation of NNMT and the loss of gap junction protein alpha-1, leading to epithelial-mesenchymal transition and consequent AdCC metastasis. CONCLUSION: NNMT is a potential biomarker of AdCC.

Introduction of ID2 Enhances Invasiveness in ID2-null Oral Squamous Cell Carcinoma Cells via the SNAIL Axis.

AIM: Inhibitor of DNA-binding (ID) proteins are negative regulators of basic helix-loop-helix transcription factors that generally stimulate cell proliferation and inhibit differentiation. However, the role of ID2 in cancer progression remains ambiguous. Here, we investigated the function of ID2 in ID2-null oral squamous cell carcinoma (OSCC) cells. MATERIALS AND METHODS: We introduced an ID2 cDNA construct into ID2-null OSCC cells and compared them with empty-vector-transfected cells in terms of cell proliferation, invasion, and activity and expression of matrix metalloproteinase (MMP). RESULTS: ID2 introduction resulted in enhanced malignant phenotypes. The ID2-expressing cells showed increased N-cadherin, vimentin, and E-cadherin expression and epithelial-mesenchymal transition. In addition, cell invasion drastically increased with increased expression and activity of MMP2. Immunoprecipitation revealed a direct interaction between ID2 and zinc finger transcription factor, snail family transcriptional repressor 1 (SNAIL1). CONCLUSION: ID2 expression triggered a malignant phenotype, especially of invasive properties, through the ID2-SNAIL axis. Thus, ID2 represents a potential therapeutic target for OSCC.

Blockade of Androgen-induced Malignant Phenotypes by Flutamide Administration in Human Salivary Duct Carcinoma Cells.

BACKGROUND/AIM: Androgens are known to play a critical role in prostate cancer progression, but their effect on malignant phenotypes in salivary gland cancer is unclear. The androgen-androgen receptor (AR) axis may be involved in malignant phenotypes of salivary duct carcinoma (SDC) cells and therefore may be a new target for SDC treatment. To test this hypothesis, we investigated the effect of the androgen 5α-dihydrotestosterone (DHT) on proliferation, migration, and invasiveness of SDC cells. MATERIALS AND METHODS: We used a wound-healing assay to measure cell migration and a Boyden chamber invasion assay to investigate SDC cell invasive capacity. RESULTS: DHT treatment increased cell proliferation, migration, and invasion. However, treatment with flutamide, an AR inhibitor, blocked the effects of DHT. CONCLUSION: These results suggest that the androgen-AR axis is involved in SDC malignancy and may be an effective therapeutic target for treatment of human SDC.

ID1 Controls Aggressiveness of Salivary Gland Cancer Cells via Crosstalk of IGF and AKT Pathways.

BACKGROUND: Inhibitor of differentiation or DNA binding 1 (ID1) is overexpressed in human salivary gland cancer (SGC). The insulin growth factor (IGF) system is an attractive target in cancer control because it is associated with various cancer progressions. MATERIALS AND METHODS: The human SGC cell line HSY with abundant ID1 was used. ID1 knockdown and its effect on the IGF system were investigated. Cell proliferation and invasion, as well as associated protein expression, were analyzed. Phospho-AKT was also evaluated. RESULTS: ID1 knockdown reduced cell proliferation and invasion, while the expression of proteins associated with malignant phenotypes was altered. IGF-II expression was suppressed, suggesting that this system is one of the mechanisms underlying effects of ID1 in SGC cells. c-Myc was up-regulated, whereas p21 and p27 were down-regulated. Moreover, phospho-AKT was reduced in ID1-knockeddown cells. CONCLUSION: ID1 down-regulation induced parallel changes in the IGF and AKT pathways. The crosstalk of these pathways may enhance malignant phenotypes in SGCs.

Estrogen Enhances Malignant Phenotypes in Human Salivary Adenoid Cystic Carcinoma Cells.

BACKGROUND/AIM: Adenoid cystic carcinoma (SGC) is a common type of salivary gland cancer (SGC). Surgery is the first treatment choice because chemoradiotherapy is usually not effective. Therefore, new treatment modalities are urgently needed. In this study, it was investigated whether the estrogen axis could be a treatment target or not. MATERIALS AND METHODS: Adenoid cystic carcinoma (ACC) ACCM cells, were used. The specific cell line lacks estrogen receptor (ER). ER was introduced in ACCM cells, and the effect of 17ß-estradiol (E2) was investigated on cell proliferation, cell-cycle distribution, and cell motility. RESULTS: E2 induced cell proliferation, and the S-phase fraction increased in a dose-dependent manner. Cell motility was also up-regulated compared to control cells. CONCLUSION: The estrogen/ER system up-regulated malignant phenotypes in ER-positive ACC, and hormone therapy may have a potential as effective treatment for this malignancy.

Custom-made titanium devices as membranes for bone augmentation in implant treatment: Clinical application and the comparison with conventional titanium mesh.

OBJECTIVE: Development of new custom-made devices to reconstruct alveolar bone for implantation, and comparison with conventional methods were the goals of this study. MATERIALS AND METHODS: Using a computer-aided design technique, three-dimensional images were constructed. From these data, custom-made devices were produced by a selective laser melting method with pure titanium. Clinical trials also have been conducted with 26 participants who needed bone reconstruction before implantation; they were divided into 2 groups with 13 patients each. The first group uses custom-made devices; the other uses commercial titanium meshes that need to bend during operation. Some clinical aspects are evaluated after the trial. RESULTS: The custom-made devices can be produced closely by following the data precisely. Devices are fit for bone defect site. Moreover, the operation time of the custom-made group (75.4 ± 11.6 min) was significantly shorter than that of the conventional group (111.9 ± 17.8 min) (p < 0.01). Mucosal rupture occurs, without significant difference (p = 0.27), in a patient in the custom-made without severe infection (7.7%), and 3 in conventional (23.1%), respectively. The retaining screw is significantly fewer in the custom-made group than commercial mesh group (p < 0.01). CONCLUSION: These results indicate that our novel protocol could be simple and safe for providing powerful support for guided bone regeneration.

A Clinical Investigation of Oral Sarcomas at Multi-institutions Over the Past 30 Years.

BACKGROUND/AIM: Sarcoma of the oral cavity is rare accounting for around 1% of all malignant oral tumors. The purpose of this study was to find important prognostic factors for patients with oral sarcoma. PATIENTS AND METHODS: The study included 1,643 patients examined from April 1980 to March 2010 at the Departments of oral and maxillofacial surgery at multi-institutions who had a histopathological diagnosis of malignant oral tumors. RESULTS: Sarcoma accounted for 19 of 1,643 cases (1.16%) in malignant oral tumors. Histologically, osteosarcoma was most common in 6 of the 19 patients, followed by 3 cases each of leiomyosarcoma and malignant fibrous histiocytoma, 2 of rhabdomyosarcoma and 1 each of angiosarcoma, Ewing's sarcoma, malignant schwannoma, malignant rhabdoid tumor and undifferentiated sarcoma. Irrespective of the histological type, tumor diameter on initial examination was >50 mm in 8 patients, 7 of whom died. Tumor diameter was <50 mm in 11 patients, 6 of whom survived. Distant metastasis was present in 11 patients, 10 of whom died. The local control rate was 42.1% and 5-year survival rate was 36.8%. CONCLUSION: Treatment of patients with tumors over 50-mm long in diameter and distant metastasis is extremely difficult. The incidence of oral sarcoma is very low. However, tumor diameter and presence of distant metastasis are important prognostic factors for oral sarcoma according to this multi-institutional study.