BackgroundThe high frequencies of recurrence and distant metastasis of adenoid cystic carcinoma (AdCC) emphasize the need to better understand the biological factors associated with these outcomes. To analyze the mechanisms of AdCC metastasis, we established the green fluorescence protein (GFP)-transfected subline ACCS-GFP from the AdCC parental cell line and the metastatic ACCS-M GFP line from an in vivo metastasis model.MethodsUsing these cell lines, we investigated the involvement of the epithelial–mesenchymal transition (EMT) and cancer stem cell (CSCs) in AdCC metastasis by real-time RT-PCR for EMT related genes and stem cell markers. Characteristics of CSCs were also analyzed by sphere-forming ability and tumorigenicity. Short hairpin RNA (shRNA) silencing of target gene was also performed.ResultsACCS-M GFP demonstrated characteristics of EMT and additionally displayed sphere-forming ability and high expression of EMT-related genes (Snail, Twist1, Twist2, Slug, zinc finger E-box binding homeobox 1 and 2 [Zeb1 and Zeb2], glycogen synthase kinase 3 beta [Gsk3β and transforming growth factor beta 2 [Tgf-β2]), stem cell markers (Nodal, Lefty, Oct-4, Pax6, Rex1, and Nanog), and differentiation markers (sex determining region Y [Sox2], Brachyury, and alpha fetoprotein [Afp]). These observations suggest that ACCS-M GFP shows the characteristics of CSCs and CSCs may be involved in the EMT of AdCC. Surprisingly, shRNA silencing of the T-box transcription factor Brachyury (also a differentiation marker) resulted in downregulation of the EMT and stem cell markers. In addition, sphere-forming ability, EMT characteristics, and tumorigenicity were simultaneously lost. Brachyury expression in clinical samples of AdCC was extremely high and closely related to EMT. This finding suggests that regulation of EMT by Brachyury in clinical AdCC may parallel that observed in vitro in this study.ConclusionsThe use of a single cell line is a limitation of this study. However, parallel data from in vitro and clinical samples suggest the possibility that EMT is directly linked to CSCs and that Brachyury is a regulator of EMT and CSCs.

The prognosis of patients with oral squamous cell carcinoma (SCC) is influenced by the presence of lymph node metastasis. Epithelial-mesenchymal transition (EMT), a process that involves events that convert adherent epithelial cells into individual migratory cells that can invade the extracellular matrix, is critical for cancer progression. Recently, the T-box transcription factor Brachyury was reported to promote EMT in human carcinoma cell lines. We analyzed the relationship between EMT (assessed by staining for E-cadherin and Vimentin) and the expression of Brachyury in association with lymph node metastasis in oral SCC. Oral SCC biopsy specimens (152 cases) were examined immunohistochemically for the expression of E-cadherin, Vimentin and Brachyury. Expression of Brachyury was correlated with EMT (p=0.035) and was significantly associated with lymph node and distant metastasis (p<0.05). Logistic regression analysis showed that Brachyury and EMT were predictive factors for lymph node metastasis (odds ratio 4.390 and 5.936, respectively) and that EMT was a predictive factor for distant metastases (odds ratio 11.786). Our findings present clinical evidence for an important role of Brachyury in EMT in oral SCC, and suggest that Brachyury and EMT patterns are useful prognostic markers.

Abstract. The prognosis of oral squamous cell carcinoma (OSCC) patients is affected by tumor recurrence and metastasis, and cancer stem cells are hypothesized to be involved in these processes. Thus, the aim of the present study was to determine whether the expression levels of five stem cell-related transcription factors, sex determining region Y-box 2 (SOX2), octamer-binding transcription factor 4 (Oct4), avian myelocytomatosis viral oncogene homolog (c-Myc), Krüppel-like factor 4 (KLF4) and brachyury, are associated with metastasis and survival in OSCC. Immunohistochemistry was performed to analyze the expression of these proteins in biopsy specimens obtained from 108 OSCC patients. The results revealed that the expression of SOX2, Oct4, KLF4 and brachyury were significantly associated with lymph node metastasis (P=0.002, P=0.031, P=0.003 and P=0.007, respectively). In addition, the expression of KLF4 and brachyury were significantly associated with distant metastasis (P=0.014 and P=0.012, respectively). Furthermore, multivariate analysis revealed that SOX2 and KLF4 are predictive factors for lymph node metastasis [odds ratios (ORs), 4.526 and 4.851, respectively], and KLF4 is also a predictive factor for distant metastasis (OR, 9.607). In addition, OSCC patients with low co-expression of SOX2, KLF4 and brachyury exhibited a significantly lower disease-specific survival rate (78.6 vs. 100%; P=0.025; χ 2 =5.033) and disease-free survival rate (60.7 vs. 90.9%; P=0.015; χ 2 =5.897) when compared with OSCC patients with high co-expression of these factors. The results indicate that SOX2, KLF4 and brachyury serve important roles in tumor progression, and these transcription factors may thus represent clinically useful prognostic markers for OSCC.

Adenoid cystic carcinoma (AdCC) is highly metastatic and resistant to chemotherapy and radiotherapy. Recently, we reported that the T-box transcription factor Brachyury is a potential regulator of cancer stem cells (CSCs). Specifically, growth of CSCs was found to be controlled by Brachyury knockdown in AdCC. Since CSCs are resistant to chemotherapy and radiotherapy, this finding provides a new principle for therapies targeting CSCs. In the present study, we established that Brachyury knockdown suppresses chemoresistance and radioresistance in vitro. Brachyury was knocked down by transfecting Brachyury short hairpin RNA (shRNA) into the AdCC CSC cell line ACCS-M GFP. Brachyury knockdown significantly inhibited cell migration and invasion and suppressed chemoresistance. A quantitative PCR array of drug transporter genes revealed that knockdown of Brachyury caused downregulation of ATP-binding cassette transporter genes. Furthermore, ACCS-M GFP radioresistance was significantly suppressed by Brachyury knockdown. Knockdown of Brachyury significantly sensitized ACCS-M GFP cells to chemoradiotherapy. This study demonstrates that Brachyury knockdown reduces invasiveness and chemoresistance and radioresistance of CSCs in vivo. Therefore, Brachyury knockdown may be a useful therapeutic tool for sensitizing CSCs to conventional chemoradiotherapy.

Objective. To evaluate the efficacy of selective submandibular neck dissection (SMND) in patients with oral squamous cell carcinoma (OSCC) with or without nodal metastasis. Patients. From a total of 384 patients with untreated OSCC who underwent radical excision, we identified 229 with clinically N0 necks and 68 with clinically N1 necks in level I. Main Outcome Measures. The Kaplan-Meier 5-year regional control and 5-year disease specific survival (DSS) were compared for SMND, radical neck dissection (RND), and modified radical neck dissection (MRND). Results. In clinically node-negative necks, the regional control rates were 85.2% with SMND and 83.3% with MRND (P = 0.89), and 5-year DSS rates were 86.5% and 87.0%, respectively, (P = 0.94). In clinically N1 necks, the regional control rates were 81.3% with SMND and 83.0% with RND (P = 0.72), and the DSS rates were 81.3% and 80.0%, respectively, (P = 0.94). Type of neck dissection was not significantly associated with regional control or DSS on either univariate or multivariate analysis using Cox's proportional hazard model. Conclusions. SMND can be effectively applied in elective and therapeutic management to patients with OSCC that are clinically assessed as N0 or N1 to level I of the neck.