Shockwaves elicited by transient pressure disturbances are used to treat musculoskeletal disorders. Previous research has shown that shockwave treatment affects T-cell function, enhancing T-cell proliferation and IL-2 expression by activating p38 mitogen-activated protein kinase (MAPK) signaling. Here we investigated the signaling pathway by which shockwaves mediate p38 MAPK phosphorylation. We found that shockwaves at an intensity of 0.18 mJ/mm(2) induce the release of extracellular ATP from human Jurkat T-cells at least in part by affecting cell viability. ATP released into the extracellular space stimulates P2X7-type purinergic receptors that induce the activation of p38 MAPK and of focal adhesion kinase (FAK) by phosphorylation on residues Tyr397 and Tyr576/577. Elimination of released ATP with apyrase or inhibition of P2X7 receptors with the antagonists KN-62 or suramin significantly weakens FAK phosphorylation, p38 MAPK activation, IL-2 expression, and T-cell proliferation. Conversely, addition of exogenous ATP causes phosphorylation of FAK and p38 MAPK. Silencing of FAK expression also reduces these cell responses to shockwave treatment. We conclude that shockwaves enhance p38 MAPK activation, IL-2 expression, and T-cell proliferation via the release of cellular ATP and feedback mechanisms that involve P2X7 receptor activation and FAK phosphorylation.

X‑box‑binding protein 1 (XBP1) contributes to various types of cancer including breast, bladder cancer and esophageal squamous cell carcinoma. The aim of the study was to examine the metastatic role of XBP1 in oral squamous cell carcinoma (OSCC), and identify possible downstream molecules. Immunohistochemical staining was conducted on tissue microarrays comprising 96 OSCC cases to determine the expression level of XBP1 and analyze its association with metastasis, clinicopathological characteristics and survival prognosis. Compared with the adjacent normal tissues of OSCC, the expression of XBP1 was significantly increased in the tumor center and front area, and lymph nodes metastases (P<0.05). A relatively high XBP1 expression was associated with histological grades (P<0.05), advanced clinical stages (P<0.05), unfavorable 5‑year survival (P=0.027). Suppressed XBP1 expression caused a significant reduction of cell invasion capability (P<0.05). AXL and the downstream molecules, such as PI3K, MMP1, MMP3, and uPA were significantly suppressed when XBP1 expression was inhibited in OSCC cells. Once XBP1 was activated by Thapsigargin, AXL expression was restored. Moreover, aberrant AXL expression was associated with XBP1 overexpression in OSCC tissues (P<0.05). In conclusion, XBP1 is a potential target that is relevant to suppressing cell invasion and is associated with patient prognosis in OSCC.

Oral squamous cell carcinoma (OSCC) represents over 90% of oral cancer incidence, while its mechanisms of tumorigenesis remain poorly characterized. In this study, we applied RNA-seq and microRNA-seq methodologies in four pairs of cancer and adjacent normal tissues to profile the contribution of miRNAs to tumorigenesis-altered functional pathways by constructing a comprehensive miRNA-mediated mRNA regulatory network. There were 213 differentially expressed (DE) miRNAs and 2172 DE mRNAs with the involvement of negative miRNA-mRNA interactions identified by at least two pairs of cancerous tissues. GO analysis revealed that the upregulated microRNAs significantly contributed to a global down-regulation of a number of transcription factors (TFs) in OSCC. Among the negative regulatory networks between the selected miRNAs (133) and TFs (167), circadian rhythm genes (RORA, RORB, RORC, and CLOCK) simultaneously regulated by multiple microRNAs were of particular interest. For instance, RORA transcript was predicted to be targeted by 25 co-upregulated miRNAs, of which, miR-503-5p, miR-450b-5p, miR-27a-3p, miR-181a-5p and miR-183-5p were further validated to directly target RORA, resulting in a stronger effect on RORA suppression together. In addition, we showed that the mRNA and protein expression levels of RORα were significantly decreased in most OSCC samples, associated with advanced clinical stage and poor prognosis. RORα significantly suppressed the proliferation of OSCC cells in vitro and in vivo. Attenuated RORα decreased p53 protein expression and suppressed p53 phosphorylation activity. Altogether, our results strongly suggest the importance of the role of miRNAs in regulating the activity of circadian rhythm-related TFs network during OSCC tumorigenesis, and provide further clues to understand the clinical link between circadian rhythm and cancer therapy.

Circadian rhythm is involved in the development and diseases of many tissues. However, as an essential environmental regulating factor, its effect on amelogenesis has not been fully elucidated. The present study aims to investigate the correlation between circadian rhythm and ameloblast differentiation and to explore the mechanism by which circadian genes regulate ameloblast differentiation. Circadian disruption models were constructed in mice for in vivo experiments. An ameloblast-lineage cell (ALC) line was used for in vitro studies. As essential molecules of the circadian system, Bmal1 and Per2 exhibited circadian expression in ALCs. Circadian disruption mice showed reduced amelogenin (AMELX) expression and enamel matrix secretion and downregulated expression of BMAL1, PER2, PPARγ, phosphorylated AKT1 and β-catenin, cytokeratin-14 and F-actin in ameloblasts. According to previous findings and our study, BMAL1 positively regulated PER2. Therefore, the present study focused on PER2-mediated ameloblast differentiation and enamel formation. Per2 knockdown decreased the expression of AMELX, PPARγ, phosphorylated AKT1 and β-catenin, promoted nuclear β-catenin accumulation, inhibited mineralization and altered the subcellular localization of E-cadherin in ALCs. Overexpression of PPARγ partially reversed the above results in Per2-knockdown ALCs. Furthermore, in in vivo experiments, the length of incisor eruption was significantly decreased in the circadian disturbance group compared to that in the control group, which was rescued by using a PPARγ agonist in circadian disturbance mice. In conclusion, through regulation of the PPARγ/AKT1/β-catenin signalling axis, PER2 played roles in amelogenin expression, cell junctions and arrangement, enamel matrix secretion and mineralization during ameloblast differentiation, which exert effects on enamel formation.

Background and Objectives Periodontitis is a chronic inflammatory disease of periodontal supporting tissues. The persistent inflammatory reaction depends on the release of chemokines to continuously recruit inflammation cells. GATA‐binding protein 4 (GATA4) exerts effects on senescence and inflammation, while its role in periodontitis is far from clear. The present study aims to address the effect of GATA4 on regulating chemokines and the chemotaxis in periodontitis. Material and Methods Periodontitis rat models were constructed to detect the expression of GATA4 and the chemokine monocyte chemoattractant protein‐1 (MCP‐1) by immunohistochemistry. Lipopolysaccharide (LPS)‐stimulated human periodontal ligament (PDL) cells and GATA4‐knockdown by siRNA transient transfection PDL cells were used to explore the correlation between GATA4 and chemokines. Transwell assay was performed to detect the role of GATA4 for the recruitment effect of chemokines on macrophages. Mitogen‐activated protein kinase (MAPK) inhibitors were scheduled to intervene in LPS‐stimulated PDL cells to examine the association between MAPK signaling pathways and GATA4. The expression of GATA4, chemokines, or MAPK signaling molecules was determined by quantitative real‐time polymerase chain reaction, western blotting, or cell immunofluorescence. Results The expression of GATA4 and MCP‐1 was significantly increased in periodontitis rat models and in LPS‐stimulated PDL cells. Knockdown GATA4 inhibited the expression of GATA4 and MCP‐1 as well as suppressed the recruitment of macrophage in LPS‐stimulated PDL cells. Inhibitors of p38 and ERK1/2 signaling pathways significantly downregulated the increased expression of GATA4 and MCP‐1 induced by LPS in PDL cells. Conclusions GATA‐binding protein 4 could act as an upstream regulator of MCP‐1 and as a downstream regulator of p38 and ERK1/2 signaling pathways to initiate inflammation response and regulate chemotaxis during the progression of periodontitis.