PO-289 Identification of microenvironmental regulation and therapeutic targeting of ongenic EF-2 kinase in pancreatic cancer

Abstract

IntroductionPancreatic cancer (PaCa) is one of the most aggressive and deadliest cancer with 6 months average survival rate. Recent studies indicate that the tumour microenvironment (TME) plays an important role in all stages of tumorigenesis in PaCa. Therefore, both tumour cells and their TME should be targeted for an effective treatment. Eukaryotic elongation factor 2 kinase (EF2K) is an enzyme which is overexpressed in cancer cells and plays a key role in cancer cell survival under stress conditions. There is no study that have shown the relationship between EF2K and TME. Thus, we investigated that the effects of EF2K expression on PaCa cell line (PANC1) and the TME.Material and methodsPANC1 cells were cocultured with monocytic THP-1 cells and macrophages were polarised from THP-1 cells. The changes in EF2K expression, cell migration and invasion were analysed using western blot, migration and invasion assays, respectively. The effects of coculture on monocyte chemoattractant protein-1 (MCP-1) levels, which is one of the most important chemokines in TME were analysed using ELISA. The role of MCP-1 on both EF2K and migration of PANC1 cells were investigated. The role of MCP-1 on monocyte-macrophage differentiation was also investigated. To determine the relationship between EF2K and MCP-1, EF2K was stably overexpressed in PANC1 cells and MCP-1 levels were measured using western blot. Then, EF2K was silenced using siRNA and the changes in MCP-1 expression levels, the ability of colony formation, migration and invasion of PANC1 cells were investigated. Pancreatic orthotopic tumour model was used to determine the in vivo effects of EF2K inhibition. In tumour tissues, the changes in expression levels of MCP-1 was measured using western blot and the presence of tumor-infiltrated pro-tumorigenic macrophages were shown using immunohistochemical staining.Results and discussionsThe interaction between PANC1 cells and macrophages caused an increase in EF2K and MCP-1 proteins and this interaction accelarated cell migration and invasion. In addition, it was found a bidirectional interaction between MCP-1 and EF2K. MCP-1 also caused differentiation of monocytes to pro-tumorigenic macrophages. In vitro silencing of EF2K decreased MCP-1 expression, cell invasion and migration. In vivo inhibition of EF2K also decreased MCP-1 expression, tumour volume and the number of tumor-infiltrated pro-tumorigenic macrophages.ConclusionTargeting both tumour cells and macrohages through EF2K inhibition might be a promising strategy for PaCa treatment.