title: Targeted p21(WAF1/CIP1) activation by miR-1236 inhibits cell proliferation and correlates with favorable survival in renal cell carcinoma.
abstract: BACKGROUND
  microRNA's function to silence gene expression by targeting 3'UTR regions has been widely studied. And microRNAs, similar to small double-stranded RNAs, have also been implicated to gene activation triggered by promoter-targeted, which is known as RNA activation (RNAa). p21(WAF1/CIP1) (p21), as a key negative regulator of cell proliferation, is frequently down-regulated in various cancers, making it an ideal target for RNAa-based activation to restore its tumor suppressor function in renal cell carcinoma (RCC).
  
  
  METHODS
  Real-time polymerase chain reaction was used to identify the expression of miR-1236 and p21 in RCC cell lines and clinical specimens. Protein expression and signaling pathway modulation were validated through Western blot analysis, whereas p21, direct target of miR-1236, was validated by using chromatin immunoprecipitation assay. The Kaplan-Meier method and the log-rank test were used to calculate overall survival. The CellTiter 96(®) AQueous One Solution Cell Proliferation Assay, colony formation assay, and 5-ethynyl-2'-deoxyuridine assays were used to evaluate the effect of miR-1236 on RCC cell proliferation.
  
  
  RESULTS
  In this study, we found that miR-1236 and p21 were both significantly down-regulated in RCC tissues and cell lines. Combined low expression of both miR-1236 and p21 emerged as an independent prognostic factor for poor clinical survival in 45 patients with RCC. Chromatin immunoprecipitation assay in the human RCC cell lines 786-O and ACHN showed that miR-1236 directly targeted the p21 promoter and that its activation may provide a plausible link between the positive correlation of miR-1236 and p21 in RCC specimens. Functional experiments showed that increased miR-1236 expression inhibited cell proliferation, and decreased CDK4/6 and cyclin D1 expression. Furthermore, knockdown of p21 using small interfering RNA reversed the antiproliferation function of miR-1236, whereas silencing the p21 expression attenuated the function of miR-1236 in RCC cells.
  
  
  CONCLUSIONS
  Our findings provide insight into the specific RNAa of miR-1236-targeted p21 promoter activation in suppressing RCC cell proliferation. Considering the poor prognostic outcomes associated with reduced miR-1236 and p21 expression, our data imply that these factors likely play important antitumor effects in RCC progression.
authors.affiliation: Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Chenghe
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Tang
authors.affiliation: Department of Pathology and Urology, Jonsson Comprehensive Cancer Center and Broad Center of Regenerative Medicine and Stem Cell Research, UCLA David Geffen School of Medicine, Los Angeles, CA.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. Electronic address: chenzhongtongji@126.com.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. Electronic address: xuhuawhu@163.com.
authors.forename: Hua
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Zhangqun
authors.initials: Z
authors.lastname: Ye
mesh_terms: D000368:Aged; D002292:Carcinoma, Renal Cell / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics* / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; C571208:MIRN1236 microRNA, human; D035683:MicroRNAs
keywords: Prognosis; Proliferation; RNAa; Renal cell carcinoma; miR-1236; p21 (Cip1/Waf1)