Wirkung von CUX1 und CD34 in Stromazellen auf das Migrations- und Proliferationsverhalten von Pankreaskarzinom-Zelllinien

A universal feature of the pancreatic ductal adenocarcinoma is the extensive desmoplastic reaction. It is characterized by a complex interplay between tumour cells and stromal cells, of mesenchymal origin and immune cells. The interplay between cells can influence proliferation, migration and subsequent invasion of pancreatic cancer cells. While the precise pathogenic mechanisms involved remains to be elucidated, autocrine and paracrine signaling molecules are thought to play a role. A better understanding of the interactions between pancreatic cancer cells and the local microenvironment could lead to new therapeutic options of the pancreatic ductal adenocarcinoma. The aim of the present study was to investigate the effect of the pathogenic microenvironment on pancreatic tumour cell proliferation as well as migration and to investigate the role of CD34 and CUX1 in mediating these effects. In order to examine the effect of the local microenvironment, mesenchymal stromal cells were co-cultured with pancreatic tumour cells in a Boyden Chamber Chemotaxis Assay. The experiments showed that supernatants from mesenchymal stromal cells induced pancreatic tumour cell migration. Increasing migration was also observed when tumour cells were cultured with supernatants from pancreatic cancer cells themselves. To examine the paracrine effect of the transmembrane protein CD34, which is expressed mainly on fibroblasts in the parenchyma adjacent to the tumour tissue NIH3T3 fibroblast cell line was stably transfected with CD34. After that pancreatic tumour cell migration and proliferation were quantified by Boyden Chamber Chemotaxis Assay and CellTiter-Glo® Luminescent Cell Viability Assay. In the experiments the supernatants or the conditioned medium from transfected CD34+-NIH3T3 cells had no effect on pancreatic tumour cell proliferation and migration. Therefore it may be suggested that the CD34 expression of the fibroblasts does not modulate the secretion of chemokines by these cells. This study then examined the effect of the transcription factor CUX1 on pancreatic cancer cells. The expression of CUX1 was assessed in macrophage and monocyte cells by western blot. Here the CUX1 protein was highly expressed on macrophage and monocyte cells. In macrophages the expression of the transcriptions factor CUX1 was regulated by TGF-β. In the Boyden Chamber Chemotaxis Assay supernatants from CUX1 suppressed mesenchymal cells had no effect on pancreatic tumour cell migration. Coculture of CUX1-suppressed U937 macrophages or control cells with pancreatic cancer cells had also no effect on pancreatic tumour cells migration rate. In contrast supernatants from CUX1-repressed J774.A1 macrophages decreased pancreatic tumour cell migration, compared to media from control cells which showed no effect. In the performed BrdU Cell Proliferation Assay conditioned media from CUX1 negative macrophages or control cells had no effect on pancreatic cancer cells proliferation. Finally the expression of chemokines, cytokines and their receptors by J774-A1 makrophages was quantified by real-time PCR. The expression profiling showed that CUX1 decreased the expression of chemokines, cytokines and their receptors involved in the inflammatory response to invading tumour cell. In summary it can be presumed that interactions of tumour cells, mesenchymal stroma cells or immune cells may play an important role in tumour progression. To what extent the expression of CD34 in mesenchymal stroma cells interferes with the interaction between the different types of cells could not be clarified. In contrast CUX1 is highly expressed on macrophages, is regulated by TGF-β and positively induces migration of pancreatic cancer cells. Furthermore CUX1 inhibits the expression of anti-proliferative and anti-inflammatory chemokines, cytokines and their receptors and thus promotes tumor cell invasion and proliferation. Therefore the interruption of the CUX1 mediated tumour invasion could be a new therapeutic option for the pancreatic ductal adenocarcinoma.