Characterization of the biological role of RIPK2 in carcinogenesis

Background. Cell survival, inflammation and cell death are the main processes involved in cellular homeostasis. The deregulation of these events can lead to the onset of several pathologies, including cancer. Receptor-Interacting Serine/Threonine Protein Kinase 2 (RIPK2) plays a key signalling role in host defence, inflammation as well as in regulated cell death (1). Till now, it is known that RIPK2, through its CARD functional domain, is able to trigger the activation of NF-kB or the MAP kinase pathway playing a fundamental role in the immune response and inflammation (2) but little scientific evidence explain the direct involvement of the protein kinase in cancer, particularly in haematological malignancies (3). Hence, more studies are necessary to better clarify its involvement in tumorigenesis and metastasis. Aim: The aim of our work is to better define the biological role of RIPK2 in cancer with a particular focus in leukaemia, in order to clarify its molecular mechanisms. Here we also provide a deeper insight into the molecular mechanism of action of new epi-drugs, highlighting their ability to directly target RIPK2. Methods: To achieve the various objectives, we have made use of RT-qPCR, Western Blot, Flow Cytometry, Immunoprecipitation, Immunofluorescence. Results. RIPK2 is differentially expressed in tumour cell lines. In particular, we focused our attention on two myeloid cell lines (U-937 and HL-60) with a different degree of differentiation for subsequent proteomic analyses and cellular localization studies. Furthermore, RIPK2 appears to be modulated after the treatment with a previously characterized epi-drug, highlighting the possible involvement of RIPK2 in the cell death process. Conclusions. The effects observed by the compound strengthen its potential role as an anti-tumor agent in leukaemia mediated by RIPK2 expression. However, further molecular and enzymatic investigations will be necessary to better understand the biological role of RIPK2 in carcinogenesis, especially in hematological malignancies.