Abstract 1552: SATB1 is a novel prognostic factor in esophageal cancer patients and promotes migration and invasion of esophageal cancer cells
Authors: Tsuruda Yusuke , Kogo Ryunosuke , Ito Shuhei , Kitagawa Akihiro , Fujii Atsushi , Kuramitsu Shotaro , Simizu Dai , Kuroda Yosuke , Eguchi Hidetoshi , Masuda Tkaaki , Natsugoe Shoji , Mori Masaki , Mimori Koshi 
Published: August 2018

Abstract
Introduction: Esophageal squamous cell carcinoma (ESCC) is a highly aggressive malignancy with extremely poor overall survival. There is no available molecular marker in clinical application until now. SATB1(special AT-rich binding protein 1) tether genomic DNA in nucleolus and hold three-dimensional structure of genomic DNA. We evaluated SATB1 expression using clinical samples from patients of ESCC and analyzed the association with clinicopathological factors and prognosis to identify novel prognostic marker in ESCC. In addition, we investigated the function of SATB1 using ESCC cells. We focused on matrix metalloproteinase protein (MMP3), which has a SATB1 binding site in its upstream.
Materials and Methods: We accumulated 71 samples of ESCC patients who underwent primary tumor resection. The relative expression levels of SATB1 were obtained by normalizing the amount of SATB1 mRNA with respect to GAPDH mRNA as an endogenous control for each sample. We divided 71 ESCC samples into 2 groups, which are SATB1 low expression group (n=35) and SATB1 high expression group (n=36) according to the median of SATB1 expression level, and performed the comparison between two groups. In order to elucidate biological significance, we generated SATB1 overexpression stable transfectants in KYSE150, and performed migration and invasion assays. Next, we knockdowned SATB1 expression of KYSE410, which are ESCC lines, using SATB1 siRNA and evaluated the capability of migration and invasion. Moreover, to validate whether SATB1 altered MMP3 genomic locus, we analyzed comparative genomic hybridization (CGH) array obtained from 54 esophageal cancer samples. We examined MMP3 expression in SATB1 overexpression cells using qRT-PCR.
Result: The SATB1 high expression group showed greater tumor depth than the low expression group (P=0.003). In the overall survival curve, patients in the SATB1 high expression group had a significant poorer prognosis than those in the SATB1 low expression group (P=0.013). Multivariate analysis showed that the level of SATB1 expression was an independent prognostic predictor (OR; 1.56, 95%CI; 1.04 - 2.44, P = 0.043). SATB1 transfectants significantly increased the capability of migration and invasion compared to mock (P&lt;0.05). KYSE410 cells transfected with SATB1 siRNA significantly decreased the capability of migration and invasion compared to control cells (P&lt;0.05). Genomic alterations in SATB1 locus were strongly correlated with those in MMP3 locus (P&lt;0.0001, ρ=0.5156). Overexpression of SATB1 showed the elevated MMP3 level compared to mock (P&lt;0.05).
Conclusion: We indicated that SATB1 is novel prognostic factor in ESCC and that SATB1 promote migration and invasion of ESCC cells. SATB1 may be a promising new candidate for targeted therapies for ESCC.
Citation Format: Yusuke Tsuruda, Ryunosuke Kogo, Shuhei Ito, Akihiro Kitagawa, Atsushi Fujii, Shotaro Kuramitsu, Dai Simizu, Yosuke Kuroda, Hidetoshi Eguchi, Tkaaki Masuda, Shoji Natsugoe, Masaki Mori, Koshi Mimori. SATB1 is a novel prognostic factor in esophageal cancer patients and promotes migration and invasion of esophageal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1552.