Abstract 3901: Sox9-associated overexpression of IFIT3 leads to pancreatic cancer progression by activation of “pseudoinflammatory” pathways
Authors: Camaj Peter , Seeliger Hendrik , Ischenko Ivan , Krebs Stefan , Renner Andrea , Jauch Karl W. , Bruns Christiane J. 
Published: February 2011

The understanding of invasion, angiogenesis and metastasis is essential for the development of new molecular therapy against cancer. Inflammation plays important role in tumour initiation and progression. Here we report the role of the transcription factor Sox9 for regulation of IFIT3 an inflammation-related and tumour-promoting protein in pancreatic cancer. For in vivo and in vitro experiments we utilized the following human pancreatic cancer cell lines: low metastatic FG, high metastatic L3.6pl, and the stable transfected cell line FG-IFIT3. To demonstrate effects on primary tumor growth and metastases in vivo we orthotopically injected the different cell lines in the pancreas of nude mice. To evaluate the VEGF depending angiogenic capacity of the different cell lines ELISA technology was used. By One STrEP technology we were able to identify IFIT3-binding partners. Chromosomal immunoprecipitation (ChIP) using anti-Sox9 antibody, followed by PCR amplifying the IFIT3-promoter was used to identify the interaction of the IFIT3 promoter with the transcription factor Sox9. To investigate Sox9-depending expression of IFIT3 (protein and RNA) we used stable transfected L3.6pl-Sox9-shRNA cells under control of the Tet-CMV promoter in presence or absence of tetracycline, respectively. Analysis of differential gene expression by gene array technology demonstrated that the IFIT3 gene is up-regulated in L3.6pl cells as compared to FG cells. Results of animal experiment and in vitro experiments clearly demonstrated tumor-promoting, pro-metastatic and pro-angiogenic features of IFIT3. RT-PCR has revealed that both treatment with IFna as well as NFkB led to up-regulation of IFIT3-RNA expression. One STrEP experiments identified JNK and STAT1 as binding partners of IFIT3. ChIP has demonstrated binding of the transcription factor Sox9 to the IFIT3 promoter. RT-PCR and immunoblot data demonstrated constitutive up-regulation of Sox9 expression in L3.6pl cells. By Western blotting and RT-PCR we could show that diminishing of Sox9 expression in stable transfected L3.6pl Sox9-shRNA cells leads to a significant down-regulation of IFIT3-epression on the RNA and protein level.

The inflammation associated protein IFIT3 is up-regulated in metastatic L3.6pl human pancreatic cancer cells and is in part responsible for the aggressive primary pancreatic tumor growth in vivo. This gene is up-regulated by IFna and NFkB. Interestingly Sox9 binds to the IFIT3P and activates its expression. Since in L3.6pl cells Sox9 is constitutively over-expressed, IFIT3 is up-regulated independent on the presence of the cytokine IFna. Therefore, the pro-inflammatory IFna-signaling pathway is activated even without actual inflammation in absence pro-inflammatory cytokine. The activation of such a “pseudo-inflammatory pathway” seems to be in part responsible for pancreatic cancer progression.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3901.