Immunohistochemical study of Dicer and Drosha expression in the benign and malignant lesions of gallbladder and their clinicopathological significances.

Dicer and Drosha are two key enzymes that are involved in the processing of miRNA production. Their expressions in gallbladder cancer have not been investigated. In this study, we studied Dicer and Drosha expression in 21 non-dysplastic gallbladder epithelia and 108 gallbladder adenocarcinomas by immunohistochemical staining. The clinicopathological significance of Dicer and Drosha expressions was analyzed. We demonstrated that the percent of positive Dicer or Drosha expression was significantly lower in gallbladder adenocarcinoma than that in non-dysplastic gallbladder epithelia (p<0.01). The percent of positive Dicer and Drosha expression was significantly lower in poorly differentiated adenocarcinoma with lymph node metastasis, invasiveness, and no resection than in well-differentiated adenocarcinoma without metastasis, invasiveness, and with radical resection (p<0.05 or p<0.01). Univariate Kaplan-Meier analysis showed that loss of Dicer and Drosha expression was associated with decreased overall survival (p<0.05 or p<0.01). Multivariate Cox regression analysis showed that loss of Dicer and Drosha expression was an independent poor-prognostic predictor in patients with gallbladder adenocarcinoma. In conclusion, loss of Dicer and Drosha expression is closely related to the metastasis, invasion, and poor-prognosis in gallbladder adenocarcinoma.