Effects Of DNMT1 And DNMT3b In Mucoepidermoid Carcinoma Of Salivary Glands

BACKGROUND AND PURPOSE: Mucoepidermoid carcinoma is a malignant tumor with characteristic cells originated from glandular epithelium.It is the most common type of salivary gland malignancy in adults,especially women from 20 to 40 years old,accounting for 3% of head and neck malignancies.The clinical manifestations of MEC are diverse,and often seen as a fixed,rubbery,painless mass in oral.Its most common symptom is swelling,followed by pain,ulcers and discoloration.While the low differentiated MEC grows rapidly with facial paralysis,local lymph node metastasis and distant metastasis of lung,liver and bone,the prognosis is poor.DNA methyltransferase(Dnmt)is essential for the catalytic and maintenance of the methylation of DNA,which can regulate the process of methylation.DNA methylation is an important factor in epigenetic phenomena and plays an important role in the process of carcinogenesis.Many studies have shown the over expression of Dnmt occurs in various cancers,such as breast cancer,ovarian cancer,prostate cancer,lymphoma and oral squamous cell carcinoma,but no reported in the MEC of salivary gland.In our study,the expression of DNMT1 and DNMT3 b in MEC and normal salivary gland tissues was detected by immunohistochemistry and we discussed the correlation of clinicopathological parameters in MEC,and searched new research findings for mucoepidermoid carcinoma of salivary glands,and provided theoretical and clinical basis for early diagnosis,targeted prevention and individualized treatment.Methods: DNMT1 and DNMT3b1 were detected by immunohistochemistry and western blot in 43 cases of MEC tissues and 17 cases of normal salivary gland tissues,which were collected from January 2010 to September 2013 in Oral and Maxillofacial Surgery department of Shengjing Hospital,all patients without preoperative radiotherapy and were confirmed by pathology.SPSS 22.0 software package was used for statistical analysis.Results: The positive expression rates of DNMT1 and DNMT3 b in MEC were 37.21% and 83.72% respectively and expressed in cytoplasm,cell membrane and nucleus by immunohistochemistry,but mainly expressed in cytoplasm and cell membrane.In normal salivary gland tissues,only a small amount of DNMT1 and DNMT3 b positive staining existed in the sample acinar ductal epithelial cells,and the positive expression rates were 17.65% and 11.76% respectively.There was no significant difference in the positive rate of DNMT1 between the control group and the MEC group,but the positive expression rate of DNMT3 b was significantly different(P < 0.01).Western blot results showed that the expression of DNMT1 in MEC tissue was higher than the control group,but no statistical difference.The expression of DNMT3 b was significantly higher than the control group with definite defference.Conclusions: High expression of DNMT3 b may play an important role in the tumorigenesis of mucoepidermoid carcinoma?...