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Background/aim: Long-term exposure to betel quid (BQ)-, cigarette-, and alcohol-induced chronic inflammation is a crucial risk factor for oral and pharyngeal squamous cell carcinoma (OPSCC) progression. We analyzed the genotypes of stromal-cell-derived factor-1 (SDF-1) and CXC-chemokine receptor-4 (CXCR4) and determined the association between their polymorphisms and the risk of OPSCC., Materials and Methods: This study consisted of 452 patients with pathologically proved OPSCC and 424 sex- and age-matched cancer-free controls. The genotypes of SDF-1 and CXCR4 were detected through the TaqMan real-time polymerase chain reaction (PCR) method., Results: Our data indicated that the C allele and C/C genotypes of CXCR4 were significantly associated with OPSCC [adjusted odds ratio (AOR)=1.41, 95% confidence interval (CI):1.02-1.96, p=0.037 and AOR=1.51, 95% CI:1.05-2.17, p=0.028, respectively] and OSCC (AOR=1.41, 95%CI:1.00-2.00, p=0.049 and AOR=1.49, 95%CI:1.01-2.20, p=0.044, respectively) risk. Patients with genetic polymorphisms of the genotype combination SDF-1/CXCR4 had a higher risk of OSCC (p trend=0.033). We analyzed the effects of CXCR4 genetic variants on susceptibility to OPSCC in patients with different risk habits of BQ chewing, tobacco smoking and alcohol consumption, and revealed that C/T+T/T genotypes exerted an increased risk only in patients with one (AOR=2.68, p=0.036) or two risk habits (AOR=2.02, p=0.027) compared to patients with the C/C genotype., Conclusion: We concluded that CXCR4 C>T can be used as a genetic marker of susceptibility to OPSCC, particularly in OPSCC patients with one or two types of risk habits with a synergistic effect., (Copyright© 2019, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

C6orf141 (Chromosome 6 open reading frame 141) is a novel gene, and its role in oral cancer progression remains unclear. C6orf141 expression in oral squamous cell carcinoma (OSCC) and adjacent normal tissues from 428 patients was examined through immunohistochemistry (IHC). Our results revealed that C6orf141 expression was significantly reduced in OSCC compared with adjacent normal tissues. Low C6orf141 expression was significantly associated with a poor American Joint Committee on Cancer pathological stage (P < 0.001), T classification (P = 0.002), and pN stage (P = 0.032). Kaplan-Meier curves revealed that low C6orf141 expression was significantly associated with shorter disease-specific survival (DSS) in patients with OSCC (log-rank P = 0.007). Multivariate analysis indicated that low C6orf141 expression was an independent prognostic biomarker for DSS (adjusted hazard ratio = 1.34; 95% confidence interval = 1.10-1.81; P = 0.05). Additionally, ectopic C6orf141 expression could significantly suppress oral cancer cell proliferation, colony formation, and migratory and invasive abilities. Xenograft tumor growth assay revealed that C6orf141 could significantly suppress oral tumor growth in vivo. Our results suggest that C6orf141 plays a novel tumor-suppressive role in oral cancer cell growth and motility. Furthermore, C6orf141 dysfunction could be a potential prognostic biomarker for OSCC and provide new therapeutic strategies in the future.

Objectives: This case-control study evaluated the association of the single nucleotide polymorphism rs7372209 (T>C) in pri-mir-26a-1 with the risk and progression of betel quid (BQ)-related oral premalignant lesions (OPLs) and oral squamous cell carcinoma (OSCC)., Study Design: In total, 597 BQ chewers were recruited: 196 healthy controls, 241 patients with OPLs, and 160 patients with OSCC. Genotypes were determined using the TaqMan real-time assay., Results: The C/T + T/T genotypes and T allele in pri-mir-26a-1 were correlated with a decreased risk of BQ-related OPLs (P = .038 and .005, respectively), oral leukoplakia (P = .01 and .001, respectively), and advanced-stage OSCC (P = .021 and .004, respectively). The effects of the C/T + T/T genotypes and T allele on the decreased risk of OPLs were potent in the older age group (both P interaction  < .001), heavy smokers (P interaction  ≤ .003 and .006, respectively) and alcohol drinkers (P interaction  ≤ .004 and .001, respectively). Furthermore, among patients with OSCC, the C/T + T/T genotypes and T allele were associated with a decreased risk of advanced pathologic stage (P = .032) and lymph node involvement (P = .017)., Conclusions: BQ chewers carrying the T allele or C/T + T/T genotypes in pri-mir-26a-1 may have a decreased risk of oral leukoplakia, OPLs, and advanced-stage OSCC., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Dysfunctional microRNAs (miRNAs) play a crucial role in oral squamous cell carcinoma (OSCC) progression. In the present study, we performed next-generation sequencing for miRNA profiling of the OSCC tissues and corresponding adjacent normal tissues in two patients with OSCC. We observed that 45 miRNAs were substantially up-regulated and 17 miRNAs were down-regulated in OSCC tissues. Since information on the biological role of miR-21-3p (passenger strand) in OSCC is limited, the expression levels of miR-21-3p were further evaluated in 95 OSCC tissue samples by a stem-loop real-time polymerase chain reaction. Our results revealed that miR-21-3p is significantly overexpressed in the OSCC tissues compared with the corresponding adjacent normal tissues (p<0.001). High miR-21-3p expression levels were significantly correlated with N classification (p=0.042). After transfection with a miR-21-3p inhibitor (antagomir), the invasive ability of the OSCC cells was significantly abrogated. Altogether, our findings indicated that miR-21-3p plays a crucial oncogenic role in cell metastasis during OSCC progression., (Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

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.

Objective: To investigate the relationships between two single-nucleotide polymorphisms at miR-146a C>G (rs2910164) and miR-1269b G>C (rs7210937) and the risk of developing oral premalignant lesions (OPLs), oral squamous cell carcinoma (OSCC), pharyngeal SCC (PSCC), and oral and pharyngeal SCC (OPSCC)., Design: Genotyping of miR-146a C>G and miR-1269b G>C was performed in two case-control studies using the TaqMan assay. A total of 197 healthy control subjects, 241 OPLs patients, and 188 OPSCC patients who habitually chewed betel quid (BQ) were recruited into one case-control study. Additionally, 668 cancer-free control subjects and 658 OPSCC patients were recruited into the other case-control study., Results: The G/G genotype at miR-146a C>G was associated with the decreased risk of OSCC [adjusted odds ratio (AOR)=0.66, P=0.040], PSCC (AOR=0.42, P=0.013), and OPSCC (AOR=0.63, P=0.020). Additionally, the C allelic type and C/C genotype at miR-1269b G>C decreased the risk of BQ-related oral leukoplakia (C vs. G: AOR=0.68, P=0.012;C/C vs. G/G: AOR=0.43, P=0.009), BQ-related OPLs (C vs. G: AOR=0.69, P=0.008;C/C vs. G/G: AOR=0.44, P=0.005), and BQ-related OPSCC (C vs. G: AOR=0.65, P=0.003;C/C vs. G/G: AOR=0.47, P=0.011). In OPSCC patients, the G/G genotype of miR-146a was correlated with well-differentiated cells (P=0.041), and the G/C and C/C genotypes of miR-1269b were correlated with the absence of lymph node involvement (P=0.031), especially in OSCC patients (P=0.038 and P=0.007, respectively)., Conclusion: The genetic variants of miR-146a and miR-1269b are biomarkers against the development of OPLs and OPSCC., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Long noncoding RNAs (lncRNAs) are more than 200 nucleotides in length and lack transcriptional ability. The biological function of lncRNAs in oral squamous cell carcinoma (OSCC) remains unclear. The aim of this study was to identify the dysfunction of lncRNA in OSCC., Results: We analyzed the transcriptome profiles of human OSCC tissues and paired adjacent normal tissues from two patients through a next-generation sequencing approach. A total of 14 lncRNAs were upregulated (fold change ≥3) and 13 were downregulated (fold change ≤-3) in OSCC tissues compared with the adjacent normal tissues. SOX21-AS1 was subjected to further analysis, revealing that the expression levels of SOX21-AS1 significantly decreased in OSCC compared with the adjacent normal tissue. The promoter activity of SOX21-AS1 was obviously suppressed by in vitro methylation. The DNA methylation status of the SOX21-AS1 promoter was analyzed using combined bisulfite restriction analysis, revealing that the aberrant promoter hypermethylation of SOX21-AS1 was observed frequently in OSCC tissues. The effects of SOX21-AS1 on cell proliferation and invasion were examined through transient transfection. Our data showed that SOX21-AS1 could significantly suppress oral cancer cell growth and invasion. Furthermore, the low expression level of SOX21-AS1 was significantly correlated with an advanced stage ( P  = 0.047), large tumor size ( P  = 0.033), and poor disease-specific survival in OSCC patients ( P  = 0.002)., Conclusions: SOX21-AS1 was identified as susceptible dysfunction correlated with promoter hypermethylation in OSCC. Low SOX21-AS1 expression may be an adverse prognostic biomarker for OSCC.

Objective: To investigate the association of miR-499a genetic polymorphism with the risk of oral leukoplakia, oral submucous fibrosis (OSF), oral squamous cell carcinoma (OSCC), and clinicopathological outcomes of OSCC., Methods: The genotyping of miR-499a T>C (rs3746444) using TagMan assay was conducted in two case-control studies of 1549 subjects. miR-499a-5p and miR-499a-3p were assayed using stem-loop RT-PCR for 63 paired OSCC and adjacent normal tissues., Results: T/C+C/C genotypes [adjusted odds ratio (AOR) 1.84, P = 0.032] and C allelic type (AOR 1.91, P = 0.007) at miR-499a T>C were associated with an increased risk of BQ-related OSF as compared to those with T/T genotype or T allelic type, respectively. Conversely, T/C+C/C genotypes and C allelic type decreased the risk of OSCC, especially for non-BQ-related OSCC (for genotype: AOR 0.49, P = 0.010; for allelic type: AOR 0.50, P = 0.007). Additionally, downregulation of miR-499a-5p was found in OSCC tissues (P = 0.001) and correlated with the TT genotype (P = 0.001)., Conclusion: The T/C+C/C genotypes of MiR-499a may contribute to an increased risk of BQ-related OSF, but a decreased risk of OSCC. miR-499a T>C influences the expression levels of miR-499a-5p during the tumorigenesis of OSCC., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)