OBJECTIVE: Osteoarthritis (OA) is one of the most common chronic joint diseases, caused by lesions in articular cartilage and synovial membranes. Synovitis is a major characteristic of OA, due to the proliferation of synoviocytes. Long noncoding RNAs (lncRNAs) have implicated to play an important role in many different diseases. The aim of this study was to verify the role of lncRNA gastric cancer-associated transcript 3 (GACAT3) in osteoarthritis. MATERIALS AND METHODS: We utilized the qRT-PCR to detect the expression of lncRNA GACAT3 in osteoarthritis synoviocytes (OAS) and normal synoviocytes (NS). The cell proliferation in NS and OAS after transfection with lncRNA-NC or lncRNA-GACAT3 was detected. The cell cycle and apoptosis rate in NS and OAS were measured by the Flow cytometry analysis. Western blot was used to analyze the possible related mechanism that GACAT3 regulated the cells proliferation in osteoarthritis. RESULTS: We found that GACAT3 expression was significantly increased in OAS compared with NS. GACAT3 expression was decreased in OAS after transfection with siRNA and the cell proliferation in OAS after transfection with siRNA was significantly inhibited. The cell cycle was arrested in G0/G1 phase and the apoptosis rate was increased in OAS after transfection with siRNA. Moreover, GACAT3 could impact the proliferation of OAS by interleukin-6/signal transducer and activator of transcription-3 (IL-6/ STAT3) signaling pathway. CONCLUSIONS: In this study, we found that lncRNA GACAT3 was closely related to the osteoarthritis. GACAT3 may be involved in the development and progression of osteoarthritis and become a potential target for treating. © 2018 Verduci Editore s.r.l. All rights reserved.