Objective:To investigate the expression level of methyltransferase-like 3 (METTL3) in nasopharyngeal carcinoma cells CNE2 and CNE-2R, and to evaluate the effect of METTL3 on cell invasion, metastasis and radiosensitivity.Methods:Real-time reverse transcription PCR and Western blot were used to detect the expression levels of METTL3 in normal nasopharyngeal epithelial cells NP69 and nasopharyngeal carcinoma cells CNE2 and nasopharyngeal carcinoma radioresistant cells CNE-2R cells. METTL3 in CNE2 and CNE-2R cells was silenced by lentivirus-mediated RNA interference technology. The metastasis and invasion abilities of the cells were detected by the scratch assay and Transwell assay. Clonogenic assay and CCK-8 assay were employed to detect the proliferation capacity and viability of cells irradiated with different X-ray doses (0, 2, 4, 6 and 8 Gy). Apoptosis was detected by flow cytometry. Methylated RNA immunoprecipitation (Me-RIP) assay was used to detect the difference in m6A modification level of c-Jun in CNE2 and CNE-2R cells after METTL3 silencing. The transcriptional stability of c-Jun in cells after silencing METTL3 was detected by actinomycin D assay. A nude mouse xenograft model was constructed to detect the effect of METTL3 on the radiosensitivity of nasopharyngeal carcinoma in vivo. Results:Compared with NP69 cells, the expression levels of METTL3 mRNA and protein were significantly increased in CNE2 cells, and the expression level was even higher in CNE-2R cells (all P<0.01). Lentivirus-mediated RNA interference technology was used to construct a stable METTL3-silencing CNE2 and CNE-2R cell lines (both P<0.01). Scratch assay and Transwell assay showed that the metastasis and invasion abilities of CNE2 and CNE-2R cells were decreased significantly after METTL3 silencing (all P<0.05). Clonogenic assay showed that silencing METTL3 significantly reduced the number of colonies and survival fraction of CNE2 and CNE-2R cells after irradiation with different doses of X-rays (all P<0.05). CCK-8 assay showed that the proliferation ability of CNE2 and CNE-2R cells was significantly reduced by silencing METTL3 (all P<0.05). After different doses of irradiation, silencing METTL3 significantly reduced the survival fraction of CNE2 and CNE-2R cells (all P<0.05). The apoptotic rate after METTL3 silencing was higher than that in the control group at the irradiation dose of 0 and 8 Gy (all P<0.05). The Me-RIP assay showed that the m6A modification level of c-Jun in CNE2 and CNE-2R cells was significantly reduced after METTL3 silencing (both P<0.01), and the actinomycin D assay showed that transcriptional stability of c-Jun was reduced. Nude mouse xenograft experiment showed that silencing METTL3 inhibited xenograft proliferation and improved its radiosensitivity. Conclusion:METTL3 is highly expressed in nasopharyngeal carcinoma cells, and METTL3 mediates m6A modification of c-Jun to improve the transcriptional stability of c-Jun and promote the expression of c-Jun, thereby promoting the invasion and metastasis of nasopharyngeal carcinoma cells and reducing their radiosensitivity.

Objective:To investigate the expression level of methyltransferase-like 3 (METTL3) in nasopharyngeal carcinoma cells CNE2 and CNE-2R, and to evaluate the effect of METTL3 on cell invasion, metastasis and radiosensitivity.Methods:Real-time reverse transcription PCR and Western blot were used to detect the expression levels of METTL3 in normal nasopharyngeal epithelial cells NP69 and nasopharyngeal carcinoma cells CNE2 and nasopharyngeal carcinoma radioresistant cells CNE-2R cells. METTL3 in CNE2 and CNE-2R cells was silenced by lentivirus-mediated RNA interference technology. The metastasis and invasion abilities of the cells were detected by the scratch assay and Transwell assay. Clonogenic assay and CCK-8 assay were employed to detect the proliferation capacity and viability of cells irradiated with different X-ray doses (0, 2, 4, 6 and 8 Gy). Apoptosis was detected by flow cytometry. Methylated RNA immunoprecipitation (Me-RIP) assay was used to detect the difference in m6A modification level of c-Jun in CNE2 and CNE-2R cells after METTL3 silencing. The transcriptional stability of c-Jun in cells after silencing METTL3 was detected by actinomycin D assay. A nude mouse xenograft model was constructed to detect the effect of METTL3 on the radiosensitivity of nasopharyngeal carcinoma in vivo. Results:Compared with NP69 cells, the expression levels of METTL3 mRNA and protein were significantly increased in CNE2 cells, and the expression level was even higher in CNE-2R cells (all P<0.01). Lentivirus-mediated RNA interference technology was used to construct a stable METTL3-silencing CNE2 and CNE-2R cell lines (both P<0.01). Scratch assay and Transwell assay showed that the metastasis and invasion abilities of CNE2 and CNE-2R cells were decreased significantly after METTL3 silencing (all P<0.05). Clonogenic assay showed that silencing METTL3 significantly reduced the number of colonies and survival fraction of CNE2 and CNE-2R cells after irradiation with different doses of X-rays (all P<0.05). CCK-8 assay showed that the proliferation ability of CNE2 and CNE-2R cells was significantly reduced by silencing METTL3 (all P<0.05). After different doses of irradiation, silencing METTL3 significantly reduced the survival fraction of CNE2 and CNE-2R cells (all P<0.05). The apoptotic rate after METTL3 silencing was higher than that in the control group at the irradiation dose of 0 and 8 Gy (all P<0.05). The Me-RIP assay showed that the m6A modification level of c-Jun in CNE2 and CNE-2R cells was significantly reduced after METTL3 silencing (both P<0.01), and the actinomycin D assay showed that transcriptional stability of c-Jun was reduced. Nude mouse xenograft experiment showed that silencing METTL3 inhibited xenograft proliferation and improved its radiosensitivity. Conclusion:METTL3 is highly expressed in nasopharyngeal carcinoma cells, and METTL3 mediates m6A modification of c-Jun to improve the transcriptional stability of c-Jun and promote the expression of c-Jun, thereby promoting the invasion and metastasis of nasopharyngeal carcinoma cells and reducing their radiosensitivity.

Objective To study the distolingual space of mandibular molars in adult patients with different sagittal skeletal patterns,and to analyze the main bony anatomical sites that restrict molar distalization,in order to provide guidance for the treatment plan of mo-lar distalization.Methods A total of 97 adult patients according to the inclusion criteria were selected from the Department of Ortho-dontics,the Affiliated Stomatological Hospital of Nanjing Medical University.The patients were divided into skeletal Class Ⅰ group(n=28),skeletal Class Ⅱ group(n=49)and skeletal Class Ⅲ group(n=20)according to the ANB angle.CBCT of the patients were im-ported into Dolphin software for 3D reconstruction.The width of the distal root of the second molar,the width of alveolar bone,the dis-tance between the most convex point of the distal and lingual side of the distal root and the inneredge of the lingual cortex of the mandi-ble were measured at the 2,4,and 6 mm plane from the root furcation to the root apex.Statistical analysis was performed using SPSS 26.0 software,and univariate analysis of variance and LSD-t test were used to compare the difference.Results Root width was significantly narrower than alveolar bone width at all measurement planes(P＜0.01).Molar distolingual space in patients with different sagittal skeletal patterns was smaller than molar distal space,and the size of the space gradually decreased with the deepening of the measurement level,reaching the minimum value at the R4 and R6 measurement planes.Measurement results of this study showed that at the R6 level,the molar distolingual space in skeletal Class Ⅱ group was the minimum(2.30±2.45)mm;on the contrary,skeletal Class Ⅲ group was the maximum(4.17±2.38)mm.Conclusion When designing the plan of molar distalization in clinical practice,CBCT should be used,and more attention should be paid to the lingual alveolar bone mass of the mandibular molar.It is a safe and effective treatment method for skeletal Class Ⅰ and Ⅲ patients with mild to moderate dental crowding.

The biological samples of oral genetic diseases and rare diseases are extremely precious. Collecting and preserving these biological samples are helpful to elucidate the mechanisms and improve the level of diagnose and treatment of oral genetic diseases and rare diseases. The standardized construction of biobanks for oral genetic diseases and rare diseases is important for achieving these goals. At present, there is very little information on the construction of these biobanks, and the standards or suggestions for the classification and coding of biological samples from oral and maxillofacial sources, and this is not conducive to the standardization and information construction of biobanks for special oral diseases. This consensus summarizes the background, necessity, principles, and key points of constructing the biobank for oral genetic diseases and rare diseases. On the base of the group standard "Classification and Coding for Human Biomaterial" (GB/T 39768-2021) issued by the National Technical Committee for Standardization of Biological Samples, we suggest 76 new coding numbers for different of biological samples from oral and maxillofacial sources. We hope the consensus may promote the standardization, and smartization on the biobank construction as well as the overall research level of oral genetic diseases and rare diseases in China.