Cryptotanshinone induces reactive oxygen species‑mediated apoptosis in human rheumatoid arthritis fibroblast‑like synoviocytes

The present study investigated the mechanisms of apoptosis induced by cryptotanshinone (CT) in human rheumatoid arthritis fibroblast‑like synoviocytes (RA‑FLSs). Cell Counting kit‑8 assay was performed to determine the cytotoxic effects of CT in human RA‑FLSs, including primary RA‑FLS, HFLS‑RA and MH7A cells, and in HFLS cells derived from normal synovial tissue. Annexin V‑FITC/PI staining was used to detect the apoptotic effects of CT in HFLS‑RA and MH7A cells. Flow cytometry was performed to detect the apoptotic and reactive oxygen species (ROS) levels induced by CT in HFLS‑RA cells. Western blotting was used to assess the expression levels of proteins associated with apoptosis and with the mitogen‑activated protein kinase (MAPK), protein kinase B (Akt), and signal transducer and activator of transcription‑3 (STAT3) signaling pathways. The results demonstrated that CT treatment significantly suppressed HFLS‑RA and MH7A cell growth, whereas no clear inhibitory effect was observed in normal HFLS cells. CT exposure downregulated the expression levels of B‑cell lymphoma 2 (Bcl‑2), p‑Akt, p‑extracellular signal‑related kinase and p‑STAT3, while it upregulated the expression levels of Bcl‑2‑associated death promoter (Bad), caspase‑3, poly (ADP‑ribose) polymerase (PARP), p‑p38 and p‑c‑Jun N‑terminal kinase. Following ROS scavenging, the CT‑induced apoptosis and altered expression levels of Bcl‑2, Bad, cleaved caspase‑3 and cleaved PARP were restored. Furthermore, the Akt, MAPK and STAT3 signaling pathways were regulated by intracellular ROS. These results suggest that ROS‑mediated Akt, MAPK and STAT3 signaling pathways serve important roles in the CT‑induced apoptosis of RA‑FLSs.