Open AccessNoncoding RNA blockade of autophagy is therapeutic in medullary thyroid cancer
Author(s) -
Gundara Justin S.,
Zhao JingTing,
Gill Anthony J.,
Lee James C.,
Delbridge Leigh,
Robinson Bruce G.,
McLean Catriona,
Serpell Jonathan,
Sidhu Stan B.
Publication year - 2015
Publication title -
cancer medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.403
H-Index - 53
ISSN - 2045-7634
DOI - 10.1002/cam4.355
Subject(s) - autophagy , atg5 , viability assay , microrna , biology , cancer research , transfection , apoptosis , cell culture , pi3k/akt/mtor pathway , cell cycle , cell , microbiology and biotechnology , gene , genetics
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 mRNA s 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.