A link between mir-100 and FRAP1/mTOR in clear cell ovarian cancer

Mol Endocrinol. 2010 Feb;24(2):447-63. doi: 10.1210/me.2009-0295. Epub 2010 Jan 15.

Abstract

MicroRNAs (miRNAs) are small noncoding RNAs that direct gene regulation through translational repression and degradation of complementary mRNA. Although miRNAs have been implicated as oncogenes and tumor suppressors in a variety of human cancers, functional roles for individual miRNAs have not been described in clear cell ovarian carcinoma, an aggressive and chemoresistant subtype of ovarian cancer. We performed deep sequencing to comprehensively profile miRNA expression in 10 human clear cell ovarian cancer cell lines compared with normal ovarian surface epithelial cultures and discovered 54 miRNAs that were aberrantly expressed. Because of the critical roles of the phosphatidylinositol 3-kinase/v-akt murine thymoma viral oncogene homolog 1/mammalian target of rapamycin (mTOR) pathway in clear cell ovarian cancer, we focused on mir-100, a putative tumor suppressor that was the most down-regulated miRNA in our cancer cell lines, and its up-regulated target, FRAP1/mTOR. Overexpression of mir-100 inhibited mTOR signaling and enhanced sensitivity to the rapamycin analog RAD001 (everolimus), confirming the key relationship between mir-100 and the mTOR pathway. Furthermore, overexpression of the putative tumor suppressor mir-22 repressed the EVI1 oncogene, which is known to suppress apoptosis by stimulating phosphatidylinositol 3-kinase/v-akt murine thymoma viral oncogene homolog 1 signaling. In addition to these specific effects, reversing the expression of mir-22 and the putative oncogene mir-182 had widespread effects on target and nontarget gene populations that ultimately caused a global shift in the cancer gene signature toward a more normal state. Our experiments have revealed strong candidate miRNAs and their target genes that may contribute to the pathogenesis of clear cell ovarian cancer, thereby highlighting alternative therapeutic strategies for the treatment of this deadly cancer.

Publication types

  • Comparative Study
  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma, Clear Cell / genetics
  • Adenocarcinoma, Clear Cell / metabolism*
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cells, Cultured
  • Computational Biology
  • Dose-Response Relationship, Drug
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism
  • Everolimus
  • Female
  • Gene Expression Profiling
  • Gene Knockdown Techniques
  • Humans
  • Intracellular Signaling Peptides and Proteins / antagonists & inhibitors
  • Intracellular Signaling Peptides and Proteins / genetics*
  • Intracellular Signaling Peptides and Proteins / metabolism
  • MicroRNAs / antagonists & inhibitors
  • MicroRNAs / chemistry
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Oligonucleotide Array Sequence Analysis
  • Ovarian Neoplasms / genetics
  • Ovarian Neoplasms / metabolism*
  • Ovary / cytology
  • Ovary / drug effects*
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors
  • Protein-Serine-Threonine Kinases / genetics*
  • Protein-Serine-Threonine Kinases / metabolism
  • RNA, Messenger / chemistry
  • Sequence Analysis, RNA
  • Sirolimus / analogs & derivatives
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases

Substances

  • Intracellular Signaling Peptides and Proteins
  • MIRN100 microRNA, human
  • MIRN22 microRNA, human
  • MicroRNAs
  • Mirn182 microRNA, human
  • RNA, Messenger
  • Everolimus
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • Protein-Serine-Threonine Kinases
  • Sirolimus