Expression And Significance Of SMG-1 Gene In HPV-positive Head And Neck Squamous Cell Carcinoma

Objective: To research the correlations between the expression and clinical significance of suppressor of morphogenesis in genitalia-1(SMG-1)in HPV-Positive head and neck squamous cell carcinoma(HNSCC),and in vitro cell experiments to further explore the mechanism of E6,SMG-1 and DNMT1 in HPV-positive HNSCC cell lines,for exploring the expression and significance of SMG-1 gene in HPV-positive HNSCC.Methods: A total of 105 cases diagnosed with HNSCC were retrospectively collected from June 2014 to December 2017,a combination detection of HPV-DNA by nest-PCR and p16 protein by immunohistochemistry was adopted for diagnosing of HPV-positive HNSCC.The correlations between the expression of SMG-1 and DNMT1 and the clinical characteristics and prognosis were analyzed,respectively.qRT-PCR was used to detect the expression of E6,DNMT1 and SMG-1 in HNSCC cells and HNSCC cells transfected with si RNA and plasmids,and to analyze the correlation among E6,DNMT1 and SMG-1;MTT the method was used to detect the influence of the expression of E6,DNMT1 and SMG-1 on the biological changes of HPV-positive HNSCC cells.Results: 1.It showed the overall HPV infection rate in HNSCC was 21.9%(23/105),33.3%(2/6)in oropharyngeal carcinoma,27.3%(3/11)in hypopharyngeal carcinoma,and 21.0%(17/81)in laryngeal carcinoma.2.(1)The positive rate of SMG-1 in HPV-positive HNSCC were 21.74%,respectively.Compared with HPV-negative HNSCC,the expression of SMG-1 in HPV-positive showed a statistical significance(P<0.05),but no statistically significant differences in the expression of gender,age,T stage and treatment method(P>0.05).There also had statistically different expression of SMG-1 in various clinical stages tumors(P<0.05).The five-year overall survival rate of HPV-positive HNSCC was higher than that of the HPV-negative HNSCC,and the negative of SMG-1 was also associated with a higher 5-year overall survival rate(P<0.05).(2)The expression of DNMT1 in HNSCC was negatively correlated with the expression of SMG-1,The positive expression of DNMT1 in HPV-positive HNSCC was(86.96%)compared with HPV-negative HNSCC,The difference was statistically significant(P< 0.05),the expression of DNMT1 in the clinical stages of tumors was statistically significant(P<0.05),and there was no significant difference in the expression of gender,age,T stage and treatment methods(P>0.05).The 5-year survival rate of HPV-positive HNSCC was higher than that of the HPV-negative group,and the DNMT1 positive group also had a higher 5-year survival rate(P<0.05).3.(1)The expression of E6 in UPCI-SCC47 and SCC-090 cell lines was significantly higher than that of HPV-negative cells,the expression of DNMT1 was higher than that of HPV-negative cells,and the expression of SMG-1 in HPV-positive cells was significantly lower than that of HPV-negative cells,The differences were statistically significant(P<0.05).(2)si RNA and plasmid transfection were performed on UPCI-SCC47 and SCC-090 cell lines,respectively.Fa Du and SCC-4 cell lines were used as controls to detect cell gene expression after treatment.The results showed:When E6 was silenced in UPCI-SCC47 and SCC-090 cells,the expression of DNMT1 m RNA decreased,while the expression of SMG-1 m RNA increased,and the difference was statistically significant(P<0.05);when DNMT1 was silenced in UPCI-SCC47 and SCC-090 cells,SMG-1 m RNA expression increased,and the difference was statistically significant(P<0.05);when DNMT1 was overexpressed in HPV-negative cells,SMG-1 m RNA The expression decreased,and the difference was statistically significant(P<0.05).(3)Silencing E6 in HPV-positive HNSCC cells increased the proliferation activity of the cells,and the difference was statistically significant(P<0.05);in HPV-positive HNSCC cells After silencing DNMT1,the proliferation activity of the cells increased.After overexpressing DNMT1 in HPV-negative HNSCC cells,the proliferation activity of the cells decreased,and the difference was statistically significant(P<0.05);silencing SMG-1 in HPV-negative HNSCC cells decreased the proliferation activity of the cells,and the difference was statistically significant(P<0.05).Conclusions: 1.The total HPV infection rate of HNSCC in native region is 21.9%,of which oropharyngeal cancer has the highest infection rate.HPV infection significantly increases the risk of HNSCC.2.HPV-positive HNSCC showed a better prognosis,compared with HPV-negative HNSCC.The expression of SMG-1 was negatively correlated with that of DNMT1 in HPV-positive HNSCC.Both the expression of SMG-1 and DNMT1 were correlated with the HNSCC prognosis.3.In HPV-positive HNSCC cells,E6 can down-regulate the expression of SMG-1through DNMT1 and inhibit the proliferation activity of HNSCC cells.