JAK2 inhibitor blocks the inflammation and growth of esophageal squamous cell carcinoma in vitro through the JAK/STAT3 pathway

: Recent research indicates that the Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) pathway may play an important role in chronic inflammation which promotes cancer progression, yet the mechanism is not clear. The present study aimed to investigate the role of the JAK/STAT3 pathway in the growth and cancer-related inflammation (CRI) of esophageal squamous cell carcinoma (ESCC) by studying the crosstalk between the JAK/STAT3 pathway and nuclear factor-κB (NF-κB) and cyclooxygenase-2 (COX-2) which are important inflammatory factors associated with tumorigenesis. Cell growth and the cell cycle were assessed by CCK-8 assays and flow cytometry, respectively. The protein levels of STAT3, phosphorylated STAT3, VEGF, NF-κB p65, phosphorylated NF-κB p65 and COX-2 in ESCC cells following treatment with JAK2 inhibitor for 48 h or interleukin-6 (IL-6) for 24 h were detected. RT-PCR was performed to study the interaction among STAT3, NF-κB and COX-2 by transfection of siRNAs targeted at STAT3 and NF-κB. STAT3 was activated in 3 ESCC cell lines at different levels. Blocking the JAK/STAT3 pathway inhibited cancer growth through regulation of cell growth, cell cycle and angiogenesis. Likewise, abrogation of the JAK/STAT3 pathway decreased CRI by downregulating levels of NF-κB p65 phosphorylation, COX-2 and IL-6 concentration. In addition, CRI and cancer growth were accelerated by IL-6 through stimulation of the JAK/STAT3 and NF-κB p65 pathway. Moreover, STAT3 and NF-κB both regulated COX-2 as a downstream gene. The JAK/STAT3 pathway is an important pathway which links CRI and cancer growth through IL-6 and crosstalk with the NF-κB p65 subunit and COX-2. The STAT3 pathway could be a novel target both for cancer treatment and prevention in ESCC.