Epigenetic Modifications Causing Sex-Specificity of Fatal TIMP-1 Expression in Pancreatic Cancer

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The exceptionally high risk to die from pancreatic cancer decisively arises from its efficient metastasis formation to the liver. Recently we found that this risk is even higher in men than in women and that the tumor-derived secreted factor TIMP-1 (Tissue Inhibitor of Metalloproteinases-1) is responsible for the sex difference in liver metastasis in this cancer entity in a life style-independent manner. In pancreatic cancer, TIMP-1 expression is male-specifically increased, while the levels remain constant in women. The mechanism regulating this sex-specificity of expression of the X-chromosomally located TIMP-1 gene is completely unknown. In this project we follow initial data showing that TIMP-1 is increasingly expressed already at early stages of the progression of this disease by malignant tumor cells and their progenitor cells, respectively, and that epigenetic reprogramming of these cells thereby seems to play a central regulatory role. In fact, based on recent studies, epigenetic reprogramming was classified as novel central ‘enabling characteristic’ during initiation of pancreatic cancer. However, possible sex differences so far have not been considered in those studies. We will investigate the molecular-mechanistic basis for sex-specific increase of TIMP-1 expression in well-established in vitro- (human pancreatic cancer cell lines) and ex vivo- (organoids derived from pancreas tissue from pancreatic cancer-bearing mice) systems, as well as already collected and stored pancreas tumor tissue samples which had been isolated from female and male patients and mice, respectively. We focus on sex-dependent accessibility of the TIMP-1 promoter as well as distal regulatory elements of the TIMP-1 gene via ATAC-seq and determination of the specific local epigenetic status (histone modification) of the TIMP-1 gene by ChIP-PCR analysis. Causal dependencies of TIMP-1 expression from histone- and DNA-modifying epigenetic enzymes will be investigated by genetic manipulation (knockdown by shRNA-technology, overexpression by retroviral gene transfer) and by pharmacological inhibition with clinically relevant inhibitors. We expect central insight into epigenetically regulated sex differences during progression of pancreatic cancer, which may contribute to more targeted therapeutic application of epigenetically active drugs (e.g. HAT- or HDAC-inhibitors) in patients.