title: MicroRNA-124 reduces the pentose phosphate pathway and proliferation by targeting PRPS1 and RPIA mRNAs in human colorectal cancer cells.
abstract: OBJECTIVE
  Cancer cells alter glucose metabolism to support their uncontrolled proliferation. Changes in microRNAs (miRNAs) have been associated with colorectal cancer (CRC) development and progression, but it is not clear whether they regulate metabolism in CRC cells. We aimed to identify miRNAs that alter glucose metabolism in CRC cells and to determine their effects on tumor development.
  
  
  METHODS
  CRC tissues and matched nontumor tissues were collected from 78 patients for messenger RNA (mRNA) analysis and from 112 patients for immunohistochemical analysis at the Fudan University Shanghai Cancer Center from 2005 through 2007. We integrated data on 100 miRNAs previously identified as potential regulators of glucose metabolism in a high-throughput screen with data on 66 miRNAs that often are deregulated in CRC cells. miRNAs with the potential to regulate glucose metabolism in CRC cells were blocked with mimics, and effects on lactate production were measured in CRC cell lines. miRNAs and their targets were overexpressed from lentivirals in CRC cell lines (LoVo and HCT-116) or knocked down with small interfering RNAs. The cells were analyzed in proliferation and colony formation assays and for growth as xenograft tumors in mice.
  
  
  RESULTS
  We identified 3 miRNAs that significantly inhibited lactate production in 3 CRC cell lines; miR124-3p (miR124) had the strongest effect. By using complementary DNA microarray analyses, we identified 67 mRNAs that were reduced in CRC cell lines that overexpressed miR124; the mRNAs encoding phosphoribosyl pyrophosphate synthetase 1 (PRPS1) and ribose-5-phosphate isomerase-A (RPIA) were found to be direct targets of miR124. Knockdown of PRPS1 and RPIA, as well as overexpression of miR124, each reduced glucose consumption and adenosine triphosphate in level CRC cells. Conversely, overexpression of PRPS1 or RPIA restored glycometabolism to these cells. RPIA and PRPS1 contribute to nucleotide metabolism and supply precursors for DNA and RNA biosynthesis. CRC cells that overexpressed miR124 or with knockdown of RPIA or PRPS1 had reduced DNA synthesis and proliferation, whereas cells incubated with an inhibitor of miR124 had significantly increased DNA synthesis and proliferation and formed more colonies. LoVo cells that overexpressed miR124 formed smaller xenograft tumors that controlled cells in mice, and had lower levels of PRPS1 and RPIA mRNA and protein. Compared with normal colorectal tissues, levels of miR124 were reduced significantly in CRC tissues from patients, whereas levels of PRPS1 and RPIA increased, which was associated with reduced patient survival times.
  
  
  CONCLUSIONS
  miR124 inhibits DNA synthesis and proliferation by reducing levels of pentose phosphate pathway enzymes in CRC cells. Expression of miR124 and its targets correlate with survival times and might be used in prognosis.
authors.affiliation: State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Zhaoping
authors.initials: Z
authors.lastname: Qiu
authors.affiliation: State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Weijie
authors.initials: W
authors.lastname: Guo
authors.affiliation: Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Qifeng
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Zhiao
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Shenglin
authors.initials: S
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Fangyu
authors.initials: F
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Yao
authors.affiliation: Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China. Electronic address: zhaoyingjun@fudan.edu.cn.
authors.forename: Yingjun
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China. Electronic address: xhhe@fudan.edu.cn.
authors.forename: Xianghuo
authors.initials: X
authors.lastname: He
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000235:genetics*; D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D010427:Pentose Phosphate Pathway / Q000235:genetics*; D011379:Prognosis; D012333:RNA, Messenger / Q000378:metabolism; D012268:Ribose-Phosphate Pyrophosphokinase / Q000235:genetics*
chemical_list: C509207:MIRN124 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger; D019344:Lactic Acid; C510474:PRPS1 protein, human; D012268:Ribose-Phosphate Pyrophosphokinase; D019747:Aldose-Ketose Isomerases; C022548:ribosephosphate isomerase; D005947:Glucose
keywords: RNA processing; colon cancer; gene expression; tumor growth