Abstract A24: Translation control of tumor metastasis via FSTL1 binding with SPP1/OPN to modulated cytoskeleton remodeling

Abstract

Abstract Follistatin-like protein 1 (FSTL1) plays a critical role in lung organogenesis. However, the prognostic significance and functional consequence of FSTL1 downregulation remains unclear in lung cancer. Here we show that the reduced levels of FSTL1 are widely detected in tumors compared to normal tissues and reflect a poor clinical outcome in non-small cell lung cancer, especially lung adenocarcinoma. Moreover, we found that FSTL1 expression negatively correlates with the metastatic potential of lung cancer cells in vitro and in vivo. Whereas the antibody-based neutralization of extracellular FSTL1 enhances the cellular migration/invasion ability, the inclusion of recombinant FSTL1 protein diminishes the metastatic capacity of lung cancer cells in vitro and in vivo. Notably, the administration of FSTL1 was capable of effectively preventing the metastatic progression of lung cancer cells in an orthotropic animal model. The in vitro protein-protein interaction (PPI) assay demonstrated that FSTL1 directly binds to the pro-form of secreted phosphoprotein 1 (SPP1), also named osteopontin (OPN), and thereby restrains the proteolytic activation of SPP1/OPN, which leads to the inactivation of integrin/CD44-associated signaling cascades and actin cytoskeleton. Runx2 and osterix transcription factors are required for the expression of SPP1/OPN. Thus, FSTL1 compromised the SPP1/OPN related translation control activity through PPI mechanism to reverse the phenotype in lung cancer. The signature of combining low-level FSTL1 with high-level SPP1 predicts a worse prognosis in lung cancer patients. This study is the first to document the PPI between FSTL1 and SPP1/OPN and our findings provide a novel and effective strategy to combat SPP1/OPN-driven metastatic cancers with FSTL1 downregulation. Citation Format: Jean Chiou, Yuan-Feng Lin, Michael Hsiao. Translation control of tumor metastasis via FSTL1 binding with SPP1/OPN to modulated cytoskeleton remodeling. [abstract]. In: Proceedings of the AACR Special Conference on Translational Control of Cancer: A New Frontier in Cancer Biology and Therapy; 2016 Oct 27-30; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2017;77(6 Suppl):Abstract nr A24.