Burning mouth syndrome (BMS) is characterized by the presence of burning sensation of the oral mucosa in the absence of clinically apparent mucosal alterations. It occurs more commonly in middle-aged and elderly women and often affects the tongue tip and lateral borders, lips, and hard and soft palate. In addition to a burning sensation, the patients with BMS may also complain unremitting oral mucosal pain, dysgeusia, and xerostomia. BMS can be classified into two clinical forms: primary and secondary BMS. The primary BMS is essential or idiopathic, in which the organic local/systemic causes cannot be identified and a neuropathological cause is likely. The diagnosis of primary BMS depends mainly on exclusion of etiological factors. The secondary BMS is caused by local, systemic, and/or psychological factors; thus, its diagnosis depends on identification of the exact causative factor. When local, systemic or psychological factors are present, treatment or elimination of these factors usually results in a significant clinical improvement of BMS symptoms. Vitamin, zinc, or hormone replacement therapy has been found to be effective for reducing the oral burning or pain symptom in some BMS patients with deficiency of the corresponding factor. If patients still have the symptoms after the removal of potential causes, drug therapy should be instituted. Previous randomized controlled clinical trials found that drug therapy with capsaicin, alpha-lipoic acid, clonazepam, and antidepressants may provide relief of oral burning or pain symptom. In addition, psychotherapy and behavioral feedback may also help eliminate the BMS symptoms.

The adenosine diphosphate (ADP) receptor P2RY12 (purinergic receptor P2Y, G protein coupled, 12) plays a critical role in platelet aggregation, and P2RY12 inhibitors are used clinically to prevent cardiac and cerebral thrombotic events. Extracellular ADP has also been shown to increase osteoclast (OC) activity, but the role of P2RY12 in OC biology is unknown. Here, we examined the role of mouse P2RY12 in OC function. Mice lacking P2ry12 had decreased OC activity and were partially protected from age-associated bone loss. P2ry12 -/-OCs exhibited intact differentiation markers, but diminished resorptive function. Extracellular ADP enhanced OC adhesion and resorptive activity of WT, but not P2ry12 -/-, OCs. In platelets, ADP stimulation of P2RY12 resulted in GTPase Ras-related protein (RAP1) activation and subsequent α IIb β 3 integrin activation. Likewise, we found that ADP stimulation induced RAP1 activation in WT and integrin β 3 gene knockout (Itgb3 -/-) OCs, but its effects were substantially blunted in P2ry12 -/-OCs. In vivo, P2ry12 -/-mice were partially protected from pathologic bone loss associated with serum transfer arthritis, tumor growth in bone, and ovariectomy-induced osteoporosis: all conditions associated with increased extracellular ADP. Finally, mice treated with the clinical inhibitor of P2RY12, clopidogrel, were protected from pathologic osteolysis. These results demonstrate that P2RY12 is the primary ADP receptor in OCs and suggest that P2RY12 inhibition is a potential therapeutic target for pathologic bone loss. IntroductionOsteoclasts (OCs) are multinucleated myeloid lineage cells that are the principal source of bone resorptive activity (1). Enhanced OC activity, bone loss, and fractures are associated with rheumatoid arthritis, postmenopausal osteoporosis, and bone metastases (2). Modulation of osteoclastic bone resorption represents an attractive point of therapeutic intervention for the treatment of such conditions.Numerous purinergic G-protein-coupled nucleotide receptors are expressed in the bone microenvironment (3, 4). For example, uridine diphosphate-activated (UDP-activated) P2Y6 has been reported to increase NF-κB activation and OC survival (5), while P2Y2 (an ATP receptor) expression on osteoblasts (OBs) blocks bone mineralization (6, 7). Hoebertz et al. demonstrated that extracellular adenosine diphosphate (ADP) stimulates OC bone resorption in vitro, in part through the ADP receptor P2Y1 on OC (8); however, other ADP receptors, including purinergic receptor P2Y, G protein coupled, 12 (P2RY12), which is the target of the widely prescribed antiplatelet drug clopidogrel (Plavix), have not been evaluated for their roles in osteoclastic bone resorption.

Background: Growing evidence indicates that heme oxygenase-1 (HO-1) is up-regulated in malignancies and subsequently alters tumor aggressiveness and various cancer-related factors, such as high glucose (HG) levels. HO-1 expression can be induced when glucose concentrations are above 25 mM; however, the role of HO-1 in lung cancer patients with diabetes remains unknown. Therefore, in this study we investigated the promotion of tumor cell invasion and the expression of metastasis-associated proteins by inducing the up-regulation of HO-1 expression by HG treatment in A549 human lung epithelial cells. Methods: The expression of HO-1and metastasis-associated protein expression was explored by western blot analysis. HO-1 enzymatic activity, reactive oxygen species (ROS) production and TGF-β₁ production were examined by ELISA. Invasiveness was analyzed using a Transwell chamber. Results: HG treatment of A549 cells induced an increase in HO-1 expression, which was mediated by the HG-induced generation of reactive oxygen species (ROS) and transforming growth factor-β1 (TGF-β₁) in a concentration- and time-dependent manner. Following the increase in HO-1 expression, the enzymatic activity of HO-1 also increased in HG-treated cells. Pretreatment with N-acetyl-L-cysteine (NAC) or with phosphatidylinositol 3-kinase (PI3K)/Akt inhibitors attenuated the HG-induced increase in HO-1 expression. HG treatment of A549 cells enhanced the invasion potential of these cells, as shown with a Transwell assay, and increased metastasis-associated protein expression. However, HO-1 siRNA transfection significantly decreased these capabilities. Conclusion: this study is the first to demonstrate that HG treatment of A549 human lung epithelial cells promotes tumor cell invasion and increases metastasis-associated protein expression by up-regulating HO-1 expression via ROS or the TGF-β₁/PI3K/Akt signaling pathway.

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Our study reveals coexpressed lncRNAs and mRNAs as transcriptional hallmarks in GC patients which provide interesting information regarding the incidence and outcome of GC.