Silencing of long‑chain non‑coding RNA GAS5 in osteoarthritic chondrocytes is mediated by targeting the miR‑34a/Bcl‑2 axis.

The present study aimed to investigate the effects of the long non‑coding RNA (lncRNA) growth arrest‑specific transcript 5 (GAS5) on proliferation, apoptosis and the inflammatory response of osteoarthritic chondrocytes (OACs) and its associated mechanism of action. Primary chondrocytes were isolated from cartilage tissues of osteoarthritis (OA) patients for subculture. GAS5 was silenced in OACs by liposome transfection. The effects of GAS5 silencing on proliferation, apoptosis, stromal metabolism and inflammatory response of OACs were analyzed. The association of GAS5 with its target microRNA‑34a (miR‑34a) and the downstream target gene Bcl‑2 was verified by luciferase reporter assays. The results indicated that GAS5 silencing promoted the proliferation, inhibited cell apoptosis and caused G1 arrest of OACs compared with the control group (P<0.05). The expression levels of TNF‑α and IL‑6 in the supernatant of OACs in the si‑GAS5 group were significantly lower than those of the control group (P<0.05). The results of the double luciferase reporter assays indicated that overexpression of GAS5 downregulated miR‑34a and upregulated Bcl‑2 levels (P<0.05) compared with the expression levels of these markers in the control group. In contrast to GAS5 overexpression, knockdown of this RNA caused a significant upregulation of miR‑34a levels and a significant downregulation in the levels of Bcl‑2 (P<0.05). Moreover, GAS5 overexpression could counteract the inhibition of apoptosis by overexpression of miR‑34a (P<0.05). The data indicated that GAS5 participated in the development of OA by regulating the biological behavior of chondrocytes via the miR‑34a/Bcl‑2 axis.