Immunhistochemische und molekularbiologische Analysen metastasierter Lymphknoten beim Prostata-Karzinom

Prostate cancer is the most common form of tumor found in men in Germany and is the third most common cause of death. When the tumor becomes metastatic and displays a systematic disease, there is an even worse prognosis. In the process of lymphatic metastasis, the sentinel-lymph nodes, which drain the primary location of the tumor, are infiltrated by disseminated tumor cells, that after proliferation form a solid metastasis. In recent years, the cytokine Growth Differentiation Factor-15 (GDF-15) has gained importance in medical research, especially in cardiovascular diseases and cancer. In the field of cancer research, it could be proven to participate in many cellular mechanisms in prostate cancer. Especially with high GDF-15 concentrations, one could see increased metastasis coinciding with its pleiotrophic effects in cancer in general. In the early stages of cancer GDF-15 seems to supress the carciogenesis while in later stages, it seems to promote it. Furthermore, investigations into the development and progression of prostate cancer could prove a correlation between the innervation and the infiltration of different immune cells, such as M1-macrophages (MΦ) and B-lymphocytes. The fact, that disseminating tumorcells metastate into lymph nodes was taken as basis for this work. From this we investigate wether GDF-15, which is found in an increased amount in prostate cancer, can also be found in the lymph nodes of prostate cancer patients and dependent on the malignancy (defined by Gleason Score (GS)) can have an increased occurence. In addition, the innervation and infiltration of immune cells (M1-MΦ and B-lymphocytes) was analysed. The presence of the immune-checkpoint ligand PD-L1, which initiates the inhibition of the immune response and therefor a better survival rate for the tumor, causes contradicting statements in prostate cancer and in metastatic lymph nodes of other cancer types. Due to PD-L1’s high clinical relevance, which goes along a positive response to immune therapy, this work also examines the expression and area ratio of it in lymph nodes. We evaluated all lymph node samples with the technique of immunostaining using different antibodies. Additionally, we analysed the antibodies GDF-15, PD-L1 and PGP 9.5 using the gene expression profiling method RT-qPCR. Neither the immunostaining, or the gene expression profiling method, could detect GDF-15 in the lymph nodes. Thus, further working hypotheses, such as the connection between M1-MΦ, B-lymphocytes, PD-L1 or the innervation and GDF-15, could not be investigated. Likewise, showing the incidence of PGP 9.5, an antibody against neurones and neuroendocrine cells, was only succesfull via RT-qPCR in one lymph node sample but unsuccesfull via immunostaining. Therefore, a connection between the innervation of the lymph node and the progression of the prostate cancer, could not be proven. In contrast, the ligand of the immuncheckpoint PD-1, PD-L1, was found in all lymph nodes samples via immunostaining and could be detected in three of five samples via RT-qPCR. Since both methods show a different trend in the summary of the respective GS, no tendency between the occurence of PD-L1 in the lymph nodes and the malignancy could be found. Moreover, we identified M1-MΦ (CD68) and B-lymphocytes (CD19) by immunostaining. M1-macrophages occur mainly in accumulation where our findings could not demonstrate a Gleason-Score dependent increase or decrease in occurence. B-lymphocytes (CD 19) were found in all lymph node samples by immunostaining, showing an higher percental ratio of the area in GS7 and GS9 than in GS6. Since GDF-15 is said to be mainly involved in the malignancy of metastatic lymph nodes, our results demonstrate for the first time, that GDF-15 could not be shown in lymph nodes neither on a molecular RNA nor a protein basis. Furthermore, the prove of expression and immunreacticity of the immune checkpoint ligand PD-L1 in the lymph node can lead to the development of new therapeutic methods for fighting metastatic lymph node cancer.