Akademik Veri Yönetim Sistemi
Tezin Türü: Doktora
Tezin Yürütüldüğü Kurum: Bursa Uludağ Üniversitesi, FEN-EDEBİYAT FAKÜLTESİ, BİYOLOJİ, Türkiye
Tezin Onay Tarihi: 2017
Tezin Dili: Türkçe
Öğrenci: DİDEM KARAKAŞ
Danışman: Egemen Dere
Özet:
Pancreatic cancer is one of the most aggressive and deadliest cancer with 6 months average survival rate. Traditional therapies only target cancer cells. However, recent studies indicate that tumor microenvironment plays an important role during tumor progression, invasion, chemoresistance and metastasis. Therefore, both tumor cells and their microenvironment should be targeted for an effective treatment. Eukaryotic elongation factor 2 kinase (EF2K) is an enzyme which is overexpressed in cancer cells that plays a key role in cancer cell survival under stress conditions. EF2K participate in invasion of pancreatic cancer cells and inhibition of this enzyme triggers apoptosis in cancer cells. There is no study that have shown the relationship between EF2K and tumor microenvironment. Therefore, in this study it has been investigated that the interaction between macrophage (one of the most abundant cell type in tumor microenvironment) and PANC1 pancreatic cancer cells on EF2K expression. In this study, PANC1 cells were cultured with monocytic THP-1 cells and macrophages which were polarized from THP-1 cells. The changes in EF2K expression, cell migration and invasion were analyzed using western blot, migration and invasion assays, respectively. The effects of coculture of PANC1 cells with monocytes and macrophages on monocyte chemoattractant protein-1 (MCP-1) levels, which is one of the most important chemokines in tumor microenvironment were analyzed 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. EF2K was silenced using siRNA and then the changes in MCP-1 expression levels, the ability of colony formation, migration and invasion of PANC1 cells were investigated. Pancreatic orthotopic tumor model was used to determine the in vivo effects of EF2K inhibition. Following EF2K inhibition, the changes in expression levels of MCP-1 was measured using western blot. The presence of tumor-infiltrated pro-tumorigenic macrophages were shown using immunohistochemical staining. As a result, it was found that the 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, there was 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, tumor volume and the number of tumor-infiltrated pro-tumorigenic macrophages. Consequently, targeting both tumor cells and macrohages through EF2K inhibition might be a promising strategy for pancreatic cancer treatment.
Key words: pancreatic cancer, tumor microenvironment, macrophage, EF2K, MCP-1