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Guanylate-binding protein 6 (GBP6) is a member of the guanylate-binding protein family, and its role in cancer has not yet been reported. We aimed to investigate the clinical significance of GBP6 in oral squamous cell carcinoma (OSCC). Next-generation sequencing was applied for analyzing differential gene expression profiling between corresponding tumor adjacent normal (CTAN) and tumor tissue from two paired OSCC patients. Real-time PCRs (RT-PCRs) were used to investigate the gene expression level of GBP6 of CTAN and tumor tissue samples from 14 TSCC patients. Immunohistochemistry was used to investigate the protein expression level of GBP6 in tumor tissues and paired CTAN tissues from 488 OSCC patients, including 183 buccal mucosa squamous cell carcinoma (BMSCC), 245 tongue squamous cell carcinoma (TSCC), and 60 lip squamous cell carcinoma (LSCC) patients. Compared with CTAN tissues of OSCC patients, GBP6 is identified as a downregulated gene using the NGS platform, which was confirmed in 14 OSCC patients by RT-PCR. Moreover, protein expression level of GBP6 in tumor tissues was lower than that in CTAN tissues and the low GBP6 expression was correlated with poor cell differentiation/lymph node metastasis in TSCC patients. In addition, TSCC patients with low expression levels of GBP6 had poor disease-specific survival rate. The low expression of GBP6 was associated with tumorigenesis and poor prognosis in OSCC patients, especially in TSCC patients. GBP6 may serve as a novel favorable diagnostic and prognostic biomarker in TSCC patients.

Simple Summary The survival rate of oral squamous cell carcinoma (OSCC) patients has not been improved in the past few decades, likely as a result of a lack of therapeutic targets. Through next generation sequencing for tumor tissues of OSCC patients, the gene expression level of guanylate binding protein 5(GBP5) was significantly elevated in tumor tissues compared with adjacent normal tissues and associated with poor prognosis in OSCC patients. Moreover, we found that GBP5 modulated cell cycle, invasion/migration, and cancer stemness in OSCC cells. Our study indicated that GBP5 might be a potential biomarker and therapeutic target for OSCC patients. Abstract Guanylate binding protein 5 (GBP5) is the interferon (IFN)-inducible subfamily of guanosine triphosphatases (GTPases) and is involved in pathogen defense. However, the role played by GBP5 in cancer development, especially in oral squamous cell carcinoma (OSCC), is still unknown. Herein, next-generation sequencing analysis showed that the gene expression levels of GBP5 were significantly higher in OSCC tissues compared with those found in corresponding tumor adjacent normal tissues (CTAN) from two pairs of OSCC patients. Higher gene expression levels of GBP5 were also found in tumor tissues of 23 buccal mucosal squamous cell carcinoma (BMSCC)/14 tongue squamous cell carcinoma (TSCC) patients and 30 oral cancer patients from The Cancer Genome Atlas (TCGA) database compared with those in CTAN tissues. Immunohistochemical results showed that protein expression levels of GBP5 were also higher in the tumor tissues of 353 OSCC patients including 117 BMSCC, 187 TSCC, and 49 lip squamous cell carcinoma patients. Moreover, TCGA database analysis indicated that high gene expression levels of GBP5 were associated with poor overall survival in oral cancer patients with moderate/poor cell differentiation, and associated with poor disease-free survival in oral cancer patients with moderate/poor cell differentiation and lymph node metastasis. Furthermore, GBP5-knockdowned cells exhibited decreased cell growth, arrest at G1 phase, and decreased invasion/migration. The gene expression of markers for epithelial−mesenchymal transition and cancer stemness was also reduced in GBP5-silenced oral cancer cells. Taken together, GBP5 might be a potential biomarker and therapeutic target for OSCC patients, especially for those with poor cell differentiation and lymph node metastasis.

// Ting-Ying Fu 1, 2, * , Chao-Nan Wu 3, 4, * , Huei-Cin Sie 1 , Jiin-Tsuey Cheng 5 , Yaoh-Shiang Lin 6 , Huei-Han Liou 7 , Yu-Kai Tseng 8, 9 , Chih-Wen Shu 7 , Kuo-Wang Tsai 7, 10 , Leing-Ming Yen 1 , Hui-Wen Tseng 11, 12 , Ching-Jiunn Tseng 7, 13, 14, 15 , Luo-Ping Ger 7, 16 , Pei-Feng Liu 7, 17 1 Department of Pathology and Laboratory Medicine, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan 2 Department of Optometry, Shu-Zen Junior College of Medicine and Management, Kaohsiung, Taiwan 3 Department of Stomatology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan 4 Department of Dental Technology, Shu-Zen Junior College of Medicine and Management, Kaohsiung, Taiwan 5 Department of Biological Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan 6 Department of Otorhinolaryngology-Head & Neck Surgery, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan 7 Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan 8 Department of Orthopedics, Show Chwan Memorial Hospital, Changhua, Taiwan 9 Department of Orthopedics, National Cheng Kung University Hospital, Tainan, Taiwan 10 Department of Chemical Biology, National Pingtung University of Education, Pingtung, Taiwan 11 Department of Dermatology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan 12 Department of Nursing, Meiho University, Pingtung, Taiwan 13 Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan 14 Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan 15 Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan 16 Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan 17 Department of Biotechnology, Fooyin University, Kaohsiung, Taiwan * These authors have contributed equally to this work Correspondence to: Luo-Ping Ger, email: lpger@vghks.gov.tw Pei-Feng Liu, email: pfliu@vghks.gov.tw Keywords: DDX60, oral cancer, subsite-specific, tumorigenesis, prognosis Received: April 14, 2016 Accepted: October 28, 2016 Published: November 08, 2016 ABSTRACT The clinical significance and biological function of DEXD/H box helicase 60 (DDX60) in oral cancer remains unknown. Herein, we evaluated the association of DDX60 expression with tumorigenesis and the prognosis of oral squamous cell carcinoma (OSCC). DDX60 expression was examined by immunohistochemistry on tissue microarray slides of 494 OSCC patients, including 180 buccal mucosal SCC (BMSCC), 241 tongue SCC (TSCC), and 73 lip SCC (LSCC) patients. DDX60 expression was significantly increased in all three subsites of OSCC compared to its expression in tumor adjacent normal tissues. However, its association with tumorigenesis was specific to the oral cavity subsite after the stratification of betel quid chewing, smoking, and drinking. Among OSCC patients, higher levels of DDX60 expression were associated with the male gender, a well-differentiated tumor, advanced stage of disease, and a large tumor size with subsite specific features. LSCC patients with high DDX60 expression levels showed shorter disease-specific survival, particularly those with moderately or poorly differentiated tumors. Additionally, TSCC or OSCC patients with high DDX60 expression showed a poor disease-free survival (DFS), particularly those with moderately or poorly differentiated tumors. Therefore, DDX60 is a novel and unfavorable biomarker for tumorigenesis and prognosis of OSCC in a subsite-specific manner.

We aimed to investigate the association of the expression levels of five epithelial–mesenchymal transition (EMT)-related proteins (Snail, Twist, E-cadherin, N-cadherin, and Vimentin) with tumorigenesis, pathologic parameters and prognosis in tongue squamous cell carcinoma (TSCC) patients by immunohistochemistry of tissue microarray. The expression levels of Snail, E-cadherin, N-cadherin and Vimentin were significantly different between the tumor adjacent normal and tumor tissues. In tumor tissues, lower E-cadherin and higher N-cadherin levels were associated with a higher grade of cell differentiation, advanced stage of disease, and lymph node metastasis. However, higher Vimentin expression was associated with poor cell differentiation and lymph node metastasis. Patients with low E-cadherin expression had poor disease-specific survival (DSS). Conversely, positive N-cadherin and higher Vimentin expression levels were associated with poor DSS and disease-free survival. Notably, our multivariate Cox regression model indicated that high Vimentin expression was an adverse prognostic factor for DSS in TSCC patients, even after the adjustment for cell differentiation, pathological stage, and expression levels of Snail, Twist, E-cadherin, and N-cadherin. Snail, E-cadherin, N-cadherin, and Vimentin were associated with tumorigenesis and pathological outcomes. Among the five EMT-related proteins, Vimentin was a potential prognostic factor for TSCC patients.