BackgroundAdenosine A2b receptor (ADORA2B) encodes an adenosine receptor that is a member of the G protein-coupled receptor superfamily. This integral membrane protein stimulates adenylate cyclase activity in the presence of adenosine. Little is known about the relevance of ADORA2B to human malignancy including oral squamous cell carcinoma (OSCC). We aimed to characterize the expression state and function of ADORA2B in OSCC.MethodsThe ADORA2B expression levels in nine OSCC-derived cells were analyzed by quantitative reverse transcriptase-polymerase chain reaction and immunoblotting analyses. Using an ADORA2B knockdown model, we assessed cellular proliferation and expression of hypoxia-inducible factor1α (HIF-1α). We examined the adenosine receptor expression profile under both normoxic and hypoxic conditions in the OSCC-derived cells. In addition to in vitro data, the clinical correlation between the ADORA2B expression levels in primary OSCCs (n = 100 patients) and the clinicopathological status by immunohistochemistry (IHC) also was evaluated.ResultsADORA2B mRNA and protein were up-regulated significantly (p < 0.05) in seven OSCC-derived cells compared with human normal oral keratinocytes. Suppression of ADORA2B expression with shRNA significantly (p < 0.05) inhibited cellular proliferation compared with the control cells. HIF-1α also was down-regulated in ADORA2B knockdown OSCC cells. During hypoxia, ADORA2B expression was induced significantly (p < 0.05) in the mRNA and protein after 24 hours of incubation in OSCC-derived cells. IHC showed that ADORA2B expression in primary OSCCs was significantly (p < 0.05) greater than in the normal oral counterparts and that ADORA2B-positive OSCCs were correlated closely (p < 0.05) with tumoral size.ConclusionOur results suggested that ADORA2B controls cellular proliferation via HIF-1α activation, indicating that ADORA2B may be a key regulator of tumoral progression in OSCCs.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1577-2) contains supplementary material, which is available to authorized users.

BackgroundGlutamate decarboxylase 1 (GAD1), a rate-limiting enzyme in the production of γ-aminobutyric acid (GABA), is found in the GABAergic neurons of the central nervous system. Little is known about the relevance of GAD1 to oral squamous cell carcinoma (OSCC). We investigated the expression status of GAD1 and its functional mechanisms in OSCCs.MethodsWe evaluated GAD1 mRNA and protein expressions in OSCC-derived cells using real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and immunoblotting analyses. To assess the critical functions of GAD1, i.e., cellular proliferation, invasiveness, and migration, OSCC-derived cells were treated with the shRNA and specific GAD1 inhibitor, 3-mercaptopropionic acid (3-MPA). GAD1 expression in 80 patients with primary OSCCs was analyzed and compared to the clinicopathological behaviors of OSCC.ResultsqRT-PCR and immunoblotting analyses detected frequent up-regulation of GAD1 in OSCC-derived cells compared to human normal oral keratinocytes. Suppression of nuclear localization of β-catenin and MMP7 secretion was observed in GAD1 knockdown and 3-MPA-treated cells. We also found low cellular invasiveness and migratory abilities in GAD1 knockdown and 3-MPA-treated cells. In the clinical samples, GAD1 expression in the primary OSCCs was significantly (P < 0.05) higher than in normal counterparts and was correlated significantly (P < 0.05) with regional lymph node metastasis.ConclusionsOur data showed that up-regulation of GAD1 was a characteristic event in OSCCs and that GAD1 was correlated with cellular invasiveness and migration by regulating β-catenin translocation and MMP7 activation. GAD1 might play an important role in controlling tumoral invasiveness and metastasis in oral cancer.

Angiopoietin-like 3 (ANGPTL3), which is involved in new blood vessel growth and stimulation of mitogen-activated protein kinase (MAPK), is expressed aberrantly in several types of human cancers. However, little is known about the relevance of ANGPTL3 in the behavior of oral squamous cell carcinoma (OSCC). In this study, we evaluated ANGPTL3 mRNA and protein in OSCC-derived cell lines (n = 8) and primary OSCCs (n = 109) and assessed the effect of ANGPTL3 on the biology and function of OSCCs in vitro and in vivo. Significant (P < 0.05) ANGPTL3 upregulation was detected in the cell lines and most primary OSCCs (60%) compared with the normal counterparts. The ANGPTL3 expression level was correlated closely (P < 0.05) with tumoral size. In patients with T3/T4 tumors, the overall survival rate with an ANGPTL3-positive tumor was significantly (P < 0.05) lower than that of ANGPTL3-negative cases. In vitro, cellular growth in ANGPTL3 knockdown cells significantly (P < 0.05) decreased with inactivated extracellular regulated kinase (ERK) and cell-cycle arrest at the G1 phase resulting from upregulation of the cyclin-dependent kinase inhibitors, including p21Cip1 and p27Kip1. We also observed a marked (P < 0.05) reduction in the growth in ANGPTL3 knockdown-cell xenografts with decreased levels of phosphorylated ERK relative to control-cell xenografts. The current data indicated that ANGPTL3 may play a role in OSCCs via MAPK signaling cascades, making it a potentially useful diagnostic/therapeutic target for use in patients with OSCC.

BackgroundNucleolar and spindle-associated protein 1 (NUSAP1) is an important mitotic regulator. In addition to its crucial function in mitosis, NUSAP1 has recently received attention due to the interesting roles in carcinogenesis. The aim of this study was to reveal functional mechanisms of NUSAP1 in oral squamous cell carcinoma (OSCC).MethodsmRNA and protein expression levels of NUSAP1 in 9 OSCC-derived cells were analyzed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and immunoblotting analyses. The correlation between the NUSAP1 expression profile and the clinicopathological factors was evaluated by immunohistochemistry (IHC) in clinical OSCC samples (n = 70). The NUSAP1 knockdown cells were established with short hairpin RNA (shRNA) in OSCC cells, and functional assays were performed using these cells. In addition to the evaluation of cellular proliferation and cell cycle, we also investigated the potential role of NUSAP1 in paclitaxel (PTX)-induced cellular responses.ResultsmRNA and protein expression of NUSAP1 were significantly up-regulated in OSCC-derived cells compared with human normal oral keratinocytes (P < 0.05). IHC revealed that NUSAP-1 expression is closely associated with primary advanced T stage (P<0.05). Suppression of NUSAP1 expression levels led to significant (P < 0.05) inhibition of cellular proliferation. Furthermore, apoptosis induced by PTX was enhanced in NUSAP1 knockdown OSCC cells.ConclusionsNUSAP1 may be a crucial biomarker for OSCC. Moreover, down-regulated NUSAP1 expression suppresses tumor proliferation and also enhances anti-tumor effect of PTX by activating apoptotic pathways. Thus, the present study strongly suggests that regulating NUSAP1 expression should contribute to the therapy for OSCC.

Cavin-2 (CVN2) affects formation of large caveolae, which are membrane-rich cholesterol domains associated with several functions in signal transduction. Accumulating evidence suggests that CVN2 is present in many cellular types; however, the molecular mechanisms of CVN2 in cancers and its clinical relevance are unknown. We proposed a mechanism by which CVN2 regulates caveolin-1 expression leading to slow cellular proliferation by inactivation of the extracellular regulated kinase (ERK) pathway. Quantitative reverse transcriptase-polymerase chain reaction and immunoblot analyses were used to assess the CVN2 regulation mechanism in oral squamous cell carcinoma (OSCC). Immunohistochemistry (IHC) was performed to analyze the correlation between CVN2 expression and clinical behavior in 115 patients with OSCC. A CVN2 overexpressed model of OSCC cells (oeCVN2 cells) was used for functional experiments. CVN2 expression was down-regulated significantly (P < 0.05) in OSCCs compared with normal counterparts in vitro and in vivo. In addition to the findings that a serum deprivation culture induced up-regulation of CVN2 and slowed cellular proliferation, oeCVN2 cell growth decreased because of cell-cycle arrest at the G1 phase resulting from up-regulated cyclin-dependent kinase inhibitors (p21(Cip1) and p27(Kip1) ) and down-regulated cyclins (cyclin D1, cyclin E) and cyclin-dependent kinases (CDK2, CDK4, and CDK6). Interestingly, CVN2 overexpression facilitated caveolin-1 recruitment and colocalization with each other. We also found decreased ERK phosphorylation levels, an upstream event in cell-cycle arrest. Clinically, IHC data from primary OSCCs showed high tumoral progression in CVN2-negative patients with OSCC. CVN2 may be a possible key regulator of OSCC progression via the CVN2/caveolin-1/ERK pathway and a potential therapeutic target for developing new treatments for OSCCs. © 2015 Wiley Periodicals, Inc.