LncRNA GAS8-AS1 inhibits cell proliferation through ATG5-mediated autophagy in papillary thyroid cancer
The long non-coding RNA GAS8 antisense RNA 1 (lncRNA GAS8-AS1) is a tumor suppressor in papillary thyroid cancer (PTC), but the mechanisms underlying how GAS8-AS1 regulates PTC biology remain unclear. Here, we evaluated the molecular function of GAS8-AS1 in regulating autophagy in PTC cell lines.
GAS8-AS1 was overexpressed and knocked down in PTC cell lines by transfecting with expression plasmids or short interfering RNAs (siRNAs). Cell proliferation was evaluated using the Cell Counting Kit-8 (CCK-8). qRT-PCR and western blot were used to determine changes in expression of autophagy-related genes. Autophagy was evaluated by immunofluorescence and transmission electron microscopy.
Relative GAS8-AS1 expression was lower in the PTC cell lines, TPC1 and BCPAP, compared to a normal thyroid cell line. Overexpression of GAS8-AS1 inhibited proliferation, significantly increased the ratio of LC3-II/LC3-I, and reduced p62 expression, whereas GAS8-AS1 knockdown demonstrated opposite effects. In GAS8-AS1 overexpressing cell lines, LC3 immunofluorescence staining demonstrated increased punctate aggregates of LC3 staining, and transmission electron microscopy revealed increased numbers of autophagosomes. Autophagy-related gene 5 (ATG5) was markedly upregulated by GAS8-AS1 overexpression and downregulated by GAS8-AS1 knockdown. Finally, silencing of ATG5 attenuated autophagy activation and rescued the inhibition of cell proliferation caused by GAS8-AS1.
In PTC cell lines, GAS8-AS1 inhibited proliferation, activated autophagy, and increased ATG5 expression. Downregulation of ATG5 reversed GAS8-AS1-mediated activation of autophagy leading to cell death, revealing a novel mechanism of the GAS8-AS1-ATG5 axis in PTC cell lines. This provided a new experimental basis to explore the effects of lncRNA on autophagy in the treatment of thyroid cancer.
KeywordslncRNA GAS8-AS1 thyroid cancer autophagy
This study was funded by the Natural Science Foundation of Liaoning Province (No. 2015020536), Liaoning BaiQianWan Talents Program (No. 2014921033), Science and Technology Project of Shenyang City (No. F16-205-1-41).
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Conflict of interest
The authors have full control of all of the primary data and agree to allow the journal to review the data if needed. The authors declare that they have no competing interests.
This article does not contain any studies with human participants or animals performed by any of the authors.
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