Study On The Methylation Of Sfrp1 And Pax1 Gene During Cervical Carcinogenesis In Xinjiang Uygur And Han

Objectives:To explore the promoter methylation status of SFRP1 and PAX1 gene in invasion cervical squamous cell carcinoma and cervical intraepithelial neoplasia in Xinjiang Uygur and Han, and to verify the correlation and variablities between SFRP1 and PAX1 gene promoter methylation and cervical carcinogenesis as well as the relevance between SFRP1 and PAX1 gene promoter methylation and HPV16 infection.Methods:1) Detecting the promoter methylation status of SFRP1 and PAX1 gene among Uygur (normal n=21; CIN1 n=11; CIN2/3 n=36; ICC n=54)and Han women (normal n=28; CIN1 n=35; CIN2/3 n=57; ICC n=58) by using Sequenom MassARRAY method.2) The 16 subtypes of HPV from all samples were detected by PCR.Results:1) Our result showed that the analyzed regions of the SFRP1 gene contained 15 CpG units (1,425 analyzed units in 122 Uygur samples and 2,250 analyzed units in 178 Han samples) and the PAX1 gene have 14 CpG units(966 analyzed units in 122 Uygur samples and 1,358 analyzed units in 178 Han samples). Many CpG units were methylated at a very low degree, only 5.2% SFRP1_CpG units had mean methylation rate>50% in Uygur people, and 7.6% in Han people; the methylation rate of PAX1 gene which was>50% showed 6.4% in Uygur women, and 17.3% in Han women, which mostly in CIN2/3 and cervical squamous cell carcinoma tissues.2) The levels of methylation of SFRP1_CpG₂.3,4 and 17 sites in Uygur tumors was significantly higher than CIN2/3 samples (P<0.0083). The mean methylation levels of SFRP1_CpG₁,7,9.10,12.13,14.15,18 and 25 were significantly increased in Han cervical squamous cell carcinomas group compared with the CIN (p<0.0083).3) The levels of methylation of PAX1_CpG₃,20 sites in Uygur tumors was significantly higher than in CIN2/3 samples (P<0.0083). The PAX1_CpG₁,4.5,6,7,8,9.10,11.12.13,14,15 and 19 sites in Han tumors was significantly higher than other groups (P<0.0083).4) No significant differences were found between the methylation levels of the SFRP1 gene and HPV 16 infection in Uygur and Han cervical squamous cell carcinoma (P>0.05). While the correlation between methylation rate of PAX1_CPG₆ and CPG₁4 subunites and HPV 16 infection of PAX1 gene have statistical significance in Han samples, but none in Uygur samples..Conclusions:The hypermethylation of CpG₁,7,9.10,12.13,14.15,18 and 25 sites of SFRP1gene which mainly accured in the process of CIN2/3 evoluted to cervical cancer was associated with Han cervical carcinogenesis, as well as the hypermethylation of CpG₁,4.5,6,7,8,9.10,11.12.13,14,15 and 19 sites of PAX1 gene; and associations also existed between the SFRP1_CpG₂.3,4 and 17 sites and PAX1_CpG₃,20 site in Uygur cercical carcinogenesis. These results indicate that the promoter methylation levels of SFRP1 and PAX1 gene of Han people was higher than Uygur people; and the hypermethylated CpG units of SFRP1 and PAX1 gene were different between Uygur and Han. There were no correlations between methylation of SFRP1 and HPV16 infection in Uygur and Han cervical carcinoma, but the methylation rate of PAX1_CpG₆ and CpG₁4 sites seemed relevant to HPV16 infection in Han cervical carcinoma.