OBJECTIVE To explore the relationship of telomerase and canceration of sinonasal inverted papilloma(IP). METHODS Telomerase activity was measured by hybridization in situ in sinonasal mucosa of 10 cases of chronic in?ammation, 45 cases of sinonasal IP with dysplasia(45 cases were divided into three groups: IP with mild dysplasia, IP with moderate dysplasia and IP with severe dysplasia, 15 cases in each group), and 21 cases of cancerated sinonasal IP. RESULTSThe positive expression rates of telomerase was 0% in sinonasal mucosa with chronic inflammation, 0% in sinonasal IP with mild dysplasia, 13.3% in sinonasal IP with moderate dysplasia, 73.3% in sinonasal IP with severe dysplasia and 80.9% in cancerated sinonasal IP. CONCLUSION Telomeras plays a critical role in malignant transformation of sinonasal IP, and it is a marker of malignant transformation tendency of sinonasal IP.

Objective:To investigate the effects of different doses of sodium arsenic (NaAsO 2) on mRNA transcription levels of nucleotide excision repair (NER) related genes in normal hepatocytes (L-02 cells) and the modification levels of histone H3 ninth lysine dimethylization (H3K9me2) in the promoter region. Methods:L-02 cells were treated with 0 (the control group) , 5, 10 and 20 μmol/L NaAsO 2 for 24 h ( n = 3). Single cell gel electrophoresis (SCGE) was used to detect DNA damage [Olive tail distance (OTM) and Tail DNA percentage (Tail DNA%)] in L-02 cells. The mRNA expression levels of Xeroderma pigmentosum (XP) gene A (XPA), XP gene D (XPD) and XP gene F (XPF) were detected by real-time fluorescence quantitative PCR. The modification levels of H3K9me2 in XPA, XPD and XPF gene promoter regions (CHIP1 and CHIP2) were detected by quantitative chromatin immunoprecipitation. Results:OTM and Tail DNA% were positively correlated with arsenic doses (in the control and 5, 10 and 20 μmol/L arsenic exposure groups, the values were 0.35 ± 0.09, 0.56 ± 0.18, 3.18 ± 0.31, 4.52 ± 0.55, 0.72 ± 0.05, 1.34 ± 0.26, 3.93 ± 0.43, 5.47 ± 0.65, respectively, r = 0.927, 0.948, P < 0.05). Compared with the control group, the mRNA expression levels of XPA, XPD and XPF in L-02 cells of 10 and 20 μmol/L arsenic exposure groups were significantly lower ( P < 0.05). Compared with the control group, the enrichment levels of H3K9me2 in XPA, XPD and XPF gene promoter regions (CHIP1 and CHIP2) in L-02 cells of 20 μmol/L arsenic exposure group were significantly higher ( P < 0.05). Conclusion:Arsenic may inhibit the transcription of NER related genes by increasing the enrichment level of H3K9me2 in the promoter regions (CHIP1 and CHIP2) of NER related genes, thereby reduce the DNA damage repair ability of L-02 cells, resulting in the aggravation of DNA damage.