Abstract 339: Apricoxib, a selective COX-2 inhibitor, suppresses IL-27-mediated STAT3 activation and potentiates its inhibition of epithelial to mesenchymal transition in human non-small cell lung cancer

Abstract

Abstract Introduction The cyclooxygenase 2 (COX-2) pathway has been implicated in the molecular pathogenesis of many cancers. Apricoxib, a selective COX-2 inhibitor, has recently been demonstrated to inhibit epithelial to mesenchymal transition (EMT) in human malignancies. EMT is a critical process in cancer progression and metastasis whereby epithelial cells undergo changes to a migratory, mesenchymal phenotype. The mechanism by which apricoxib may alter the tumor microenvironment by impacting other important pathways in EMT is poorly defined. To investigate this concept, we utilized Interleukin-27 (IL-27), a member of the IL-12 family, which signals through the JAK-STAT pathway and activates transcriptional factors with opposing roles in carcinogenesis, STAT1 (tumor suppressor) and STAT3 (oncogene). IL-27 has been shown to have anti-tumor activity, but understanding of its mechanism is limited. We previously demonstrated that IL-27 activates both STAT1 and STAT3 pathways in human non-small cell lung cancer (NSCLC) and that the balance in STAT1 and STAT3 activation is important in inhibiting EMT. Here, we studied the effect of apricoxib on IL-27-mediated STAT activation and EMT inhibition. We hypothesize that apricoxib modulates STAT1 and STAT3 activation and regulates EMT. Methods A human NSCLC cell line, A549, was pre-treated with apricoxib (80nM-10µM) for up to 24 hours prior to IL-27 stimulation (50ng/mL). Activation of STAT1 and STAT3 proteins, demonstrated by tyrosine phosphorylation, was measured by Western Blot analysis. Additionally, epithelial markers (E-cadherin, γ-catenin, β-catenin) and mesenchymal markers (N-cadherin, vimentin, snail) were evaluated also by Western blotting. Results IL-27 alone induced phosphorylation of STAT1 and STAT3 proteins compared to untreated control. Pre-treatment with apricoxib resulted in decreased levels of IL-27-mediated STAT1 and STAT3 phosphorylation compared to the IL-27 alone group. Apricoxib alone did not cause STAT1 or STAT3 activation. IL-27 treatment alone increased the levels of E-cadherin, γ-catenin, and β-catenin and decreased the levels of N-cadherin, vimentin, and snail compared to untreated control. Pre-treatment with apricoxib for 24 hours prior to IL-27 exposure resulted in potentiation of IL-27-mediated reduction of N-cadherin, vimentin, and snail and further increased the levels of E-cadherin when compared to the IL-27 alone group. There appeared to be no impact on the expression of γ-catenin or β-catenin with the addition of apricoxib to IL-27. Conclusions Apricoxib inhibits IL-27-mediated activation of STAT1 and STAT3, and potentiates the IL-27-mediated inhibition of epithelial to mesenchymal transition. These findings suggest that apricoxib may regulate EMT through modulation of the STAT pathway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 339. doi:1538-7445.AM2012-339