Kang-Ai Injection Inhibits Gastric Cancer Cells Proliferation through IL-6/STAT3 Pathway

Objective:To explore the mechanisms underlying the proliferative inhibition of Chinese herbal medicine Kang-Ai injection(KAI)in gastric cancer cells.Methods:Gastric cancer cell lines MGC803 and BGC823 were treated by 0,0.3%,1%,3%and 10%KAI for 24,48 and 72 h,respectively.The cell proliferation was evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide(MTT)assay.The apoptosis and cell cycle were evaluated by flow cytometry.Interleukin(IL)-6 mRNA and protein expression levels were detected by quantitative real-time polymerase chain reaction(qRT-PCR)and enzyme-linked immune sorbent assay(ELISA),respectively.The protein expression levels of cyclin A,cyclin E,cyclin B1,cyclin D1,p21,retinoblastoma(RB),protein kinase B(AKT),extracellular regulated protein kinases(ERK),signal transducer and activator of transcription(STAT)1 and STAT3 were detected by Western blot.Results:KAI inhibited the proliferation of MGC803 and BGC823 gastric cancer cells in dose-and time-dependent manner.After treated with KAI for 48 h,the proportion of G,phase was increased,expression level of cyclin D1 and phosphorylation-RB were down-regulated,whereas the expression of p21 was up-regulated(all P<0.01).Furthermore,48-h treatment with KAI decreased the phosphorylation level of STAT3,inhibited the mRNA and protein expressions of IL-6(all P<0.01).IL-6 at dose of 10 ng/mL significantly attenuated the proliferative effect of both 3%and 10%KAI,and recovered KAI-inhibited STAT3 phosphorylation and cyclin D1 expression level(all P<0.01).Conclusion:KAI exerted an anti-proliferative function by inhibiting IL-6/STAT3 signaling pathway followed by the induction of G_(1)phase arrest in gastric cancer cells.