Aberrant Promoter Methylation Of WWOX, Smad4 In Esophageal Squamous Cell Carcinoma

Objective:Esophageal squamous cell carcinoma(ESCC)is one of the frequent kind of digestive system malignant tumours. In recent years, many valuable studies have been reported. However many measures have been done for the cancer,early diagnosis of the cancer is hard to achieve because patients in the early stage have no obvious symptoms,and majority of patients treated in hospital are in the late stage.It is necessary to conduct a study of its pathogenesis, in order to reduce the ESCC morbidity and mortality.Recently, the DNA methylation has been the hot spot. The purpose of this study was to investigate the methylation of gene WWOX and Smad4 in ESCC and corresponding normal tissues, and we tried to explore the relationship between gene methylation and the carcinogenesis, metastasis and pathological differentiation of ESCC, and provide a new theory and experiment evidence for pathogenesy, gene therapy and immunotherapy, clinical prognosis of Esophageal squamous cell carcinoma.Methods1 We used a methylation specific PCR (MSP) method to examine the methylation status of the 5' CpG island of WWOX and Smad4 gene in 69 tumors and 48 corresponding normal tissues.2 We used a RT- PCR method to examine the mRNA expression of WWOX and Smad4 in 44 cases of carcinoma and 15 cases of adjacent tissues.3 SPSS13.0 was applied to analyze the results of experiment. Results1 WWOX gene was methylated in 18 of 69 (26.1%) tumor specimens, which was significantly higher than that in corresponding tissues 4.2% (2/48) (P<0.05). Methylation frequencies of WWOX inⅢ/ⅣGroup 43.3 % was significantly higher than that inⅠ/Ⅱgroup 12.8% in TNM. Methylation frequencies of WWOX in lymph node metastasis group 35.5% was higher than that in no lymph node metastasis group 18.4%, methylation frequencies of WWOX gene had difference in different age and gender groups, but all no significance (P>0.05).2 Smad4 gene was methylated in 2 of 69 (2.9%) tumor specimens, which was lower than that in corresponding tissues 8.3% (4/48),but no significance (P>0.05).3 WWOX mRNA expression quantity in esophagealsquamous cellcarcinoma (0.77±0.16) was significantly lower than adjacent tissues (0.89±0.12)(P<0.05);Smad4 mRNA expression quantity in Esophageal squamous cell carcinoma (0.75±0.17) was significantly lower than adjacent tissues (0.88±0.14)(P<0.05);There was no significant correlation between theWWOX and Smad4 mRNA expression quantity and age,gender,pathologieal tyPe,pathologieal grade,lymphatic metastasis(p>0.05).4 In esophageal squamous cell carcinoma tissues, the WWOX mRNAexpression quantity of methylated group (0.73±0.15) was lower than that(0.76±0.17) of unmethylated group,but no significance (P>0.05).Conclusions1 The methylation frequencies of WWOX in ESCC was significantly higher than that in corresponding normal tissues, indicating that the methylation of WWOX gene may be related with oncogenesis of ESCC;the methylation frequencies of Smad4 in ESCC was lower than that in corresponding normal tissues ,but no significance, indicating that the methylation of Smad4 gene may be no related with oncogenesis of ESCC.2 Methylation frequencies of WWOX inⅢ/Ⅳgroup was significantly higher than that inⅠ/Ⅱgroup in TNM, indicating that the methylation of WWOX gene may be related with invasion of ESCC.