RSK are a group of kinases of the ribosomal protein s6 kinase family consisting of four isoforms (RSK1-4) and are regulated via the Ras-ERK1/2 pathway. In the literature, this group of kinases was associated with functions essential for the survival and development of tumors through the control of transcription, translation and proliferation, among other functions. However, studies of our group showed that the two chemical inhibitors more used for RSKs (SL0101 and BI-D1870) are non-specific, generating the need for a reevaluation of the functions described for the kinases. To date, the role of RSK isoforms in glioblastomas (GBM) is not well understood. RSK isoforms expression was studied in five GBM cell lines (LN18, LN229, U87MG, A172 and U118MG). We observed that the expression of RSK1 is variable between the different cell lines, where LN-18 cells display higher levels of this isoform. RSK2 is expressed in similar levels among the cells, while, RSK3 and 4 were not detected. To understand the effects of the kinases, we generated LN-18 knockout cells for the different RSK isoforms by the CRISPR/Cas9 technique. As a result, we obtained knockout cells for RSK1, RSK2 and double knockout cells for isoforms RSK1 and 2. The aim of the present project is to characterize the phenotypes and biological effects dependent on each of the isoforms. We will analyze the effects of the isoforms of RSKs on proliferation, cell cycle, migration, invasion and survival, which are important processes for GBM tumor biology. We also hope to determine what are the specific effects of RSK inhibitors using the knockout cells. All data will be critical to establishing the potential of RSKs as a therapeutic target for GBM.
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