Long noncoding RNA GAS5 promotes apoptosis in primary nucleus pulposus cells derived from the human intervertebral disc via Bcl‑2 downregulation and caspase‑3 upregulation

: Nucleus pulposus cell (NPC) apoptosis serves an important role in intervertebral disc degeneration (IDD); however, the roles of long noncoding RNAs (lncRNAs) in this process remain unknown. The present study aimed to determine the effects of the lncRNA growth arrest‑specific transcript 5 (GAS5) on the apoptosis of primary human NPCs derived from the intervertebral disc, and to investigate the underlying mechanisms. TargetScan was used to predict the lncRNAs targeted by microRNA‑155 (miR‑155). Then, NPCs were subjected to lentivirus‑mediated transduction of miR‑155 or GAS5. A human lncRNA and mRNA array was used to screen differentially expressed lncRNAs following miR‑155 overexpression. GAS5 and miR‑155 expression levels were determined by reverse transcription‑quantitative polymerase chain reaction. After GAS5 overexpression, apoptosis was assessed by flow cytometry via Annexin V/propidium iodide staining. Western blotting was employed to determine the expression of apoptosis‑associated proteins, including caspase‑3 and B cell lymphoma 2 (Bcl‑2). TargetScan indicated GAS5 had one binding site for miR‑155. Following exogenous transfection of miR‑155 mimics, GAS5 expression levels in NPCs were significantly decreased (P<0.05). Interestingly, miR‑155 overexpression in NPCs resulted in 721 differentially expressed lncRNAs compared with the negative control group (P<0.05), including 492 and 229 upregulated and downregulated lncRNAs respectively. In addition, 18 transcripts of GAS5 exhibited a downregulated expression profile. GAS5 overexpression in NPCs resulted in enhanced caspase‑3 decreased Bcl‑2 expression levels; the apoptosis of NPCs was significantly increased (P<0.05). The results of the present study revealed that overexpression of lncRNA GAS5 may promotes NPC apoptosis via Bcl‑2 downregulation and caspase‑3 upregulation, which may be associated with miR‑155. The results of the present study suggest that lncRNA GAS5‑silenced NPCs, or lentivirus‑mediated lncRNA GAS5 knockdown may be precise and effective therapeutic strategies in the treatment of IDD.