ABSTRACT
MicroRNAs are tiny but powerful regulators of gene expression at the post-transcriptional level. Aberrant expression of oncogenic and tumor-suppressor microRNAs has been recognized as a common feature of human cancers. Colorectal cancer represents a major clinical challenge in the developed world and the design of innovative therapeutic approaches relies on the identification of novel biological targets. Here, we perform a functional screening in colorectal cancer cells using a library of locked nucleic acid (LNA)-modified anti-miRs in order to unveil putative oncogenic microRNAs whose inhibition yields a cytotoxic effect. We identify miR-1285-3p and further explore the effect of its targeting in both commercial cell lines and primary colorectal cancer stem cells, finding induction of cell cycle arrest and apoptosis. We show that DAPK2, a known tumor-suppressor, is a novel miR-1285 target and mediates both the anti-proliferative and the pro-apoptotic effects of miR-1285 depletion. Altogether, our findings uncover a novel oncogenic microRNA in colorectal cancer and lay the foundation for further studies aiming at the development of possible therapeutic strategies based on miR-1285 targeting.
Subject(s)
Apoptosis/physiology , Cell Proliferation/physiology , Colorectal Neoplasms/genetics , Colorectal Neoplasms/metabolism , Death-Associated Protein Kinases/metabolism , MicroRNAs/genetics , MicroRNAs/metabolism , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Cell Cycle Checkpoints , Cell Line, Tumor , Cell Proliferation/drug effects , Colonic Neoplasms/genetics , Colonic Neoplasms/metabolism , Death-Associated Protein Kinases/genetics , Gene Expression Regulation, Neoplastic/drug effects , Humans , Neoplastic Stem Cells , OligonucleotidesABSTRACT
Treatment of lung cancer is an unmet need as it accounts for the majority of cancer deaths worldwide. The development of new therapies urges the identification of potential targets. MicroRNAs' expression is often deregulated in cancer and their modulation has been proposed as a successful strategy to interfere with tumor cell growth and spread. We recently reported on an unbiased high-content approach to identify miRNAs regulating cell proliferation and tumorigenesis in non-small cell lung cancer (NSCLC). Here we studied the oncogenic role of miR-663 in NSCLC biology and analyzed the therapeutic potential of miR-663 targeting. We found that miR-663 regulates apoptosis by controlling mitochondrial outer membrane permeabilization (MOMP) through the expression of two novel direct targets PUMA/BBC3 and BTG2. Specifically, upon miR-663 knockdown the BH3-only protein PUMA/BBC3 directly activates mitochondrial depolarization and cell death, while BTG2 accumulation further enhances this effect by triggering p53 mitochondrial localization. Moreover, we show that miR-663 depletion is sufficient to elicit cell death in NSCLC cells and to impair tumor growth in vivo.
