title: MiRNA-26b inhibits proliferation by targeting PTGS2 in breast cancer.
abstract: MicroRNAs (miRNAs) are small, non-coding RNAs (20-24 nucleotides) that post-transcriptionally modulate gene expression by negatively regulating the stability or translational efficiency of their target mRNAs. The aim of this study was to investigate the expression pattern of microRNA-26b (miR-26b) in human breast cancer, and its potential role in disease pathogenesis.
  
  
  
  Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to determine the expression level of miR-26b in 38 breast cancer specimens and adjacent normal breast tissues. MTT assays were conducted to explore the impact of miR-26b overexpression on the proliferation of human MDA-MB-231 breast cancer cells. Luciferase reporter assays were employed to validate regulation of a putative target of miR-26b. The effect of modulating miR-26b on endogenous levels of this target were subsequently confirmed via qRT-PCR and Western blot.
  
  
  
  MiR-26b expression was relatively decreased in breast cancer specimens compared with adjacent normal tissues (P<0.01). Overexpression of miR-26b suppressed MDA-MB-231 cell growth. Luciferase assays using a reporter carrying a putative miR-26b target site in the 3' untranslated region of PTGS2 revealed that miR-26b directly targets PTGS2. Overexpression of miR-26b led to downregulation of PTGS2 at the mRNA and protein level, as assessed by qRT-PCR and Western blot. Targeted knockdown of PTGS2 by siRNA significantly inhibited the proliferation of MDA-MB-231 breast cancer cells.
  
  
  
  MiR-26b may act as a tumor suppressor in breast cancer. The overexpression of miR-26b inhibits cellular growth by targeting PTGS2, suggesting its use as a potential therapeutic target for breast cancer.
authors: Department of Breast and Thyroid, Shanghai Tenth People's Hospital, Shanghai, 200072, China.
authors: Jia
authors: J
authors: Li
authors: Department of Breast and Thyroid, Shanghai Tenth People's Hospital, Shanghai, 200072, China.
authors: Xiangjie
authors: X
authors: Kong
authors: Department of Breast and Thyroid, Shanghai Tenth People's Hospital, Shanghai, 200072, China.
authors: Junfeng
authors: J
authors: Zhang
authors: Department of Breast and Thyroid, Shanghai Tenth People's Hospital, Shanghai, 200072, China.
authors: Qifeng
authors: Q
authors: Luo
authors: Department of Breast and Thyroid, Shanghai Tenth People's Hospital, Shanghai, 200072, China.
authors: Xiaoyu
authors: X
authors: Li
authors: Department of Breast and Thyroid, Shanghai Tenth People's Hospital, Shanghai, 200072, China.
authors: Lin
authors: L
authors: Fang
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