Objectives: This study aimed to determine expressions of methyltransferase-like 3 (METTL3) and METTL14, two enzymes essential for mRNA methylation at the adenosine (m 6 A), in oral squamous cell carcinoma (OSCC) and to investigate in vitro aggressiveness of their aberrant expressions. Methods: METTL3 and METTL14 expressions in 50 OSCC and 11 normal oral tissues were examined by immunohistochemistry. METTL3 and METTL14 expressions and m 6 A amounts were determined in three OSCC cell lines, including HN5, HN6, and HN15. Cell proliferation, migration, and invasion were studied by BrdU, wound healing, and Transwell chamber assays, after silencing of METTL3, METTL14, or both by siRNA transfection. Results: Immunostaining of METTL3 and METTL14 was localized in cancer cell nuclei.The mean percentages of METTL3-and METTL14-positive cells were significantly increased in OSCC tissues (p < 0.001). The percentages of METTL3-and METTL14positive cells were correlated with the advanced pTNM stages (p < 0.05) and with the degrees of histopathological differentiation in OSCC (r = 0.564 and r = 0.316, respectively; p < 0.001). By the COX multivariate analysis, both overexpressed METTL3 and METTL14 were significantly associated with short overall survival (p < 0.05).Both METTL3 and METTL14 expressions and the m 6 A amounts were significantly increased in HN6 (p < 0.05). Silencing of METTL3 and METTL14 in HN6 significantly inhibited cell proliferation (p < 0.01), but it failed to mitigate cell migration or invasion.Conclusions: METTL3 and METTL14 are overexpressed in OSCC tissues and in the HN6 OSCC cell line that promotes cell proliferation. Overexpressed METTL3 or METTL14 is found to be an independent prognostic factor for short overall survival in patients with OSCC.

Methylenetetrahydrofolate reductase (MTHFR) is a central enzyme involved in regulating the metabolic function of folate, which plays a pivotal role in DNA synthesis, repair, and methylation. The role of MTHFR C677T polymorphism in oral cancer risk has been reported with conflicting evidence. We conducted this study to appropriately estimate the effect size. We searched eligible studies in medicine-specific databases (PubMed, EMBASE, and Web of Knowledge) using (polymorphism) OR (polymorphisms) AND (methylenetetrahydrofolate reductase) OR (MTHFR) AND (oral cancer). A total of seven studies were summarized. This meta-analysis of the combined data showed a marginal association of MTHFR C677T polymorphism with oral cancer risk [odds ratio (OR) = 0.86, 95% confidence interval (CI) = 0.73-1.00 for CT vs. CC]. We also found decreased oral cancer risk in Asian population and hospital-based studies. Moreover, heavy drinkers were found to have a significantly higher risk of developing such cancer as compared to the non-heavy drinkers. These results suggest that MTHFR C677T polymorphism may play a role in oral cancer carcinogenesis in Asian population and heavy drinkers.

The aims of this study were to determine the functional roles of the transmembrane glycoprotein, Disintegrin and metalloproteinase domain-containing protein 9 (ADAM 9), in the phosphorylation of epidermal growth factor receptor (EGFR) and AKT and in the aggressiveness of oral cancer cells. Immunohistochemistry and immunoblotting were conducted to determine expression of ADAM 9 and the levels of EGFR phosphorylated at the tyrosine 1173 residue (p-EGFR tyr1173 ) and AKT phosphorylated at the serine 473 residue (p-AKT ser473 ) in oral cancer tissues and in the oral cancer cell lines HN5, HN6, HN15, and HN008. Small interfering RNA (siRNA) was used to inhibit expression of ADAM9 mRNA, and thus production of ADAM9 protein, in oral cancer cells. ADAM9-knockdown cells were examined for p-EGFR tyr1173 and p-AKT ser473 levels and used for cell proliferation and invasion assays. A positive correlation among overexpression of ADAM 9, p-EGFR tyr1173 , and p-AKT ser473 was found in oral cancer tissues.

Background: Several studies have demonstrated a role of O-GlcNAcylation (O-GlcNAc) in tumorigenesis of various carcinomas by modi cation of tumor-associated proteins. However, its implication in the pathogenesis of osteosarcoma remains unclear. This study aimed to investigate the levels of O-GlcNAc and the expressions of O-linked N-acetylglucosamine transferase (OGT) and O-GlcNAcase (OGA) in human osteosarcoma tissues and to nd correlations between the levels or expressions and several clinicopathologic parameters.Methods: Immunohistochemistry was conducted in 109 formalin-xed, para n-embedded bone tissue sections that were derived from 109 rst diagnosed osteosarcoma patients, including Enneking stage IIB (n=70) and III (n=39). Correlations between the imunoreactive score (IRS) and clinicopathologic parameters, overall survival, and metastasis-free survival were evaluated.Results: A positive correlation was found between the IRS of OGA and the percentage of postchemotherapeutic tumor necrosis (r=0.308; P=0.017). Univariate analysis revealed signi cantly lower OGA IRS in metastatic patients (P=0.020) and poor chemotherapeutic-responder patients (P=0.001). By multivariate analysis, presence of tumor metastasis (P=0.002) and lower OGA IRS (P=0.004) was signi cantly associated with shorter overall survival. Subgroup analysis in stage IIB osteosarcoma (n=70) demonstrated that male gender (P=0.019), presence of tumor recurrence (P=0.026), poor chemotherapeutic responder (P=0.022), and lower OGA IRS (P=0.019) were signi cantly correlated with short metastasis-free survival. But, lower OGA IRS was the only independent predictor for short metastasis-free survival (P=0.006).Conclusions: O-GlcNAc pathway, especially OGA, involved in pathogenesis and aggressiveness of osteosarcoma. Low level of OGA expression may be used as a poor prognostic indicator. BackgroundO-GlcNAcylation (O-GlcNAc) is a post-translational modi cation of proteins associated with regulation of various protein functions by an addition of N-acetylglucosamine (GlcNAc) to the hydroxyl group of serine or threonine residues of the target proteins. This modi cation is a dynamic and reversible process, strictly regulated by two important enzymes, O-linked N-acetylglucosamine transferase (OGT) and O-GlcNAcase (OGA), which add and remove the GlcNAc moieties, respectively. 1-5 O-GlcNAc is involved in many cellular processes, such as signal transduction, transcription, cell cycle control, and epigenetic control of gene expressions in response to stress and nutrient imbalance. 6,7 In this regard, O-GlcNAc homeostasis needs to be maintained in order to achieve proper cellular functions.Aberrations of O-GlcNAc are associated with the pathogenesis of many human diseases, including diabetes, neurodegenerative diseases and cancers. 6,[8][9][10][11] With respect to cancer pathogenesis and progression, several key players, such as p53, c-Myc, Forkhead box M1 (FoxM1) etc., have been shown to