Expression and clinical significance of the DNA repair enzyme MYH in esophageal squamous cell carcinoma.

MYH is an important enzyme in combating DNA oxidative stress in the occurrence and development of various types of tumors. To investigate the correlation between expression of the DNA repair enzyme MYH in esophageal squamous cell carcinoma and 8-oxoguanine (8-oxoG) oxidative damage, as well as the clinical significance of altered MYH expression, tissues from 175 esophageal carcinoma cases were investigated in the present study. MYH expression and 8-oxoG oxidative damage in squamous cell carcinoma and adjacent normal tissue were assessed by immunohistochemistry and Western blotting. In 82.9% (145/175) of the cases, MYH protein expression in esophageal squamous cell carcinoma was lower than that of adjacent normal tissue (t=4.24, P<0.001). Additionally, 8-oxoG staining was higher in the tumors than in the normal tissue. Lower expression of MYH in esophageal squamous cell carcinoma was associated with depth of invasion, venous invasion, TNM stage and lymph node metastasis (P<0.05). In conclusion, a lower MYH expression level in esophageal cell carcinoma tissue was inversely associated with more severe 8-oxoG oxidative damage, suggesting that changes in MYH activity correspond to increased DNA damage in tumor cells. The use of MYH expression as a postoperative index for esophageal squamous cell carcinoma may guide the formulation of individualized chemotherapy for patients after surgery.