Curcumin inhibits the CAF-induced chemoresistance of GC through the suppression of the JAK/STAT3 signaling pathway. (A) Western blot analysis showing the expression of indicated proteins following co-culture with CAFs and with/without curcumin in MKN1, MKN74 and SNU668 cells. (B) Western blot analysis showing the expression of indicated proteins following co-culture with CAFs and with/without curcumin under 5-FU treatment. (C) Relative viability of MKN74 and SNU668 cells co-cultured with fibroblast culture-conditioned media and treated with 5-FU and curcumin. (D) Western blot analysis showing changes in the expression of apoptotic markers, such as cleaved PARP, at 72 h following 5-FU and curcumin treatment of GC cells with or without co-culture with CAFs. (E) Flow cytometry with Annexin V/PI double-staining showing that 5-FU treatment with curcumin significantly increased the number of Annexin V+/PI+ cells. Data are presented as the mean values. *P<0.05 and **P<0.01. 5-FU, 5-fluorouracil; CAF, cancer-associated fibroblast; JAK, Janus-activated kinase; STAT3, signal transducer and activator of transcription 3.