title: Noncoding RNA blockade of autophagy is therapeutic in medullary thyroid cancer.
abstract: Micro-RNAs are dysregulated in medullary thyroid carcinoma (MTC) and preliminary studies have shown that miRNAs may enact a therapeutic effect through changes in autophagic flux. Our aim was to study the in vitro effect of miR-9-3p on MTC cell viability, autophagy and to investigate the mRNA autophagy gene profile of sporadic versus hereditary MTC. The therapeutic role of miR-9-3p was investigated in vitro using human MTC cell lines (TT and MZ-CRC-1 cells), cell viability assays, and functional mechanism studies with a focus on cell cycle, apoptosis, and autophagy. Post-miR-9-3p transfection mRNA profiling of cell lines was performed using a customized, quantitative RT-PCR gene array card. This card was also run on clinical tumor samples (sporadic: n = 6; hereditary: n = 6) and correlated with clinical data. Mir-9-3p transfection resulted in reduced in vitro cell viability; an effect mediated through autophagy inhibition. This was accompanied by evidence of G2 arrest in the TT cell line and increased apoptosis in both cell lines. Atg5 was validated as a predicted miR-9-3p mRNA target in TT cells. Post-miR-9-3p transfection array studies showed a significant global decline in autophagy gene expression (most notably in PIK3C3, mTOR, and LAMP-1). Autophagy gene mRNAs were generally overexpressed in sporadic (vs. hereditary MTC) and Beclin-1 overexpression was shown to correlate with residual disease. Autophagy is a tumor cell survival mechanism in MTC that when disabled, is of therapeutic advantage. Beclin-1 expression may be a useful prognostic biomarker of aggressive disease.
authors.affiliation: Cancer Genetics, Kolling Institute of Medical Research, St. Leonards, Sydney, New South Wales, Australia; Endocrine Surgical Unit, Royal North Shore Hospital, St. Leonards, Sydney, New South Wales, Australia.
authors.forename: Justin S
authors.initials: JS
authors.lastname: Gundara
authors.forename: JingTing
authors.initials: J
authors.lastname: Zhao
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Gill
authors.forename: James C
authors.initials: JC
authors.lastname: Lee
authors.forename: Leigh
authors.initials: L
authors.lastname: Delbridge
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Robinson
authors.forename: Catriona
authors.initials: C
authors.lastname: McLean
authors.forename: Jonathan
authors.initials: J
authors.lastname: Serpell
authors.forename: Stan B
authors.initials: SB
authors.lastname: Sidhu
mesh_terms: D051017:Apoptosis Regulatory Proteins / Q000235:genetics; D001343:Autophagy / Q000187:drug effects*; D000071187:Autophagy-Related Protein 5; D000071186:Beclin-1; D018278:Carcinoma, Neuroendocrine; D045744:Cell Line, Tumor; D002470:Cell Survival; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000235:genetics; D035683:MicroRNAs / Q000235:genetics / Q000494:pharmacology*; D008869:Microtubule-Associated Proteins / Q000235:genetics; D018365:Neoplasm, Residual; D013964:Thyroid Neoplasms / Q000235:genetics*
chemical_list: C502778:ATG5 protein, human; D051017:Apoptosis Regulatory Proteins; D000071187:Autophagy-Related Protein 5; C491997:BECN1 protein, human; D000071186:Beclin-1; C541874:MIRN92 microRNA, human; D008565:Membrane Proteins; D035683:MicroRNAs; D008869:Microtubule-Associated Proteins
keywords: Autophagamir; MTC; autophagy; medullary; miR-9-3p; oncophagy