ag-490 and Esophageal-Squamous-Cell-Carcinoma

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.

Topics: Carcinoma, Squamous Cell; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cyclooxygenase 2; Enzyme Inhibitors; Esophageal Neoplasms; Esophageal Squamous Cell Carcinoma; Humans; Inflammation; Interleukin-6; Janus Kinase 2; NF-kappa B; Phosphorylation; Signal Transduction; STAT3 Transcription Factor; Tyrphostins

To detect the expression of phosphorylated-signal transducer and activator of transcription 3 (p-Stat3) and myeloid leukemia-1 (Mcl-1) as well as their correlation, and to investigate the functional role of Stat3 and Mcl-1 in the pathogenesis of esophageal squamous cell carcinoma (ESCC).. Stat3 activity in ESCC cells was inhibited with JAK/Stat3 inhibitors (AG490 or JSI-124). Specific siRNA was used to inhibit the Stat3 expression. Cell apoptosis was detected by flow cytometry. Expression of Mcl-1 protein was determined by Western blotting. Expression of phospho-Stat3 (Tyr705) and myeloid leukemia-1 (Mcl-1) proteins in ESCC tissues was detected by tissue microarray and immunohistochemistry. The relationship between p-Stat3 or Mcl-1 aberrant expression and clinicopatholohical features of ESCC was analyzed. The correlation of their expression was also analyzed.. Suppression of the Stat3 signaling activation in ESCC cells led to marked apoptosis, and dramatic reduction of Mcl-1 protein. The positive rate of phospho-Stat3 (Tyr705) expression was 45.0% in 50/111 of the ESCC tissue samples. The lower the degree of tumor differentiation, the higher the positive rate of phospho-Stat3 (Tyr705), showing a significant difference (P = 0.018). The positive rate of Mcl-1 protein expression was 72.1% (80/111), and the lower the degree of tumor differentiation was, the higher there was the positive rate of Mcl-1, with a significant difference (P = 0.026). There was a positive correlation between the expressions of p-Stat3 and Mcl-1 proteins (P = 0.012).. In a subset of ESCC tissues, p-Stat3 (Tyr705) and Mcl-1 are overexpressed and positively correlated with each other, and both are correlated with tumor differentiation. Persistent activation of Stat3 contributes to apoptotic resistance in ESCC cells, and may be at least partly mediated through upregulation of Mcl-1.

Topics: Antineoplastic Agents; Apoptosis; Carcinoma, Squamous Cell; Cell Differentiation; Cell Line, Tumor; Cell Survival; Esophageal Neoplasms; Esophageal Squamous Cell Carcinoma; Humans; Myeloid Cell Leukemia Sequence 1 Protein; Neoplasm Grading; Neoplasm Staging; Phosphorylation; RNA, Small Interfering; STAT3 Transcription Factor; Tyrphostins