title: The Significance of miR-34a Expression in Endometrial Carcinogenesis: Correlation With Expression of p16 and Ki-67 Proteins in Endometrial Cancers.
abstract: BACKGROUND
  A microRNA, miR-34a, plays a key role in inhibiting cellular transformation and carcinogenesis by controlling cell cycle regulation and cell proliferation in various human tumors. However, miR-34a has rarely been reported in endometrial cancer research in Korea. This study was undertaken to analyze miR-34a expression in simple endometrial hyperplasia and endometrial cancer, and to evaluate the relationship between expression of miR-34a and p16 and Ki-67 proteins in endometrial cancers.
  
  
  METHODS
  A retrospective study was carried out on 66 formalin-fixed, paraffin-embedded tissues with simple endometrial hyperplasia (31 cases) and endometrial cancer (35 cases) patients. These were analyzed for miR-34a expression by quantitative real-time PCR, and the expression of p16 and Ki-67 proteins in endometrial cancers was evaluated by immunohistochemistry.
  
  
  RESULTS
  The miR-34a expression level was lower in endometrial cancer tissues (-0.71 ± 3.90) than in simple endometrial hyperplasia tissues (2.68 ± 8.62). The endometrial hyperplasia tissues showed underexpression of miR-34a in 13 of the 31 cases (41.9%) while the endometrial cancer tissues showed underexpression of miR-34a in 24 of 35 cases (68.6%). Thus, miR-34a was significantly underexpressed in endometrial cancer tissues when compared endometrial hyperplasia tissues (P = 0.046). Overexpression of p16 was detected in 25 (71.4%) and Ki-67 immunoreactivity was detected in 27 (77.1%) of the 35 endometrial cancers. Although not statistically significant, the frequency of p16 and Ki-67 overexpression tended to be lower in the cases with miR-34a underexpression than in cases with miR-34a overexpression.
  
  
  CONCLUSIONS
  These findings suggest that underexpression of miR-34a might be involved in endometrial carcinogenesis. Further studies are needed to define the relationship between miR-34a expression and tissue specific protein expression.
authors.affiliation: Department of Clinical Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan, Korea.
authors.forename: Yoon Sung
authors.initials: YS
authors.lastname: Choi
authors.affiliation: Department of Clinical Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan, Korea.
authors.forename: Kyung Eun
authors.initials: KE
authors.lastname: Lee
keywords: Endometrial cancer; Ki-67; Simple endometrial hyperplasia; miR-34a; p16