Cisplatin induces the rearrangement of RBPs on CDKN1B/p27 mRNA

Cisplatin (CP) is a chemotherapeutic drug that is used to cure different types of cancer. CP induces DNA damage and leads to cell cycle arrest. The cyclin-dependent kinase inhibitor 1B (CDKN1B), also termed p27, plays an important role in the drug response ; and increased levels of p27 correlated with CP resistance. In HEK293 cells, we observed that p27 mRNAs levels increased whereas protein level drastically decreased in cells treated with CP; suggesting post-transcriptional regulatory events. To further understand the underlying mechanisms, we applied a biochemical approach combined with mass-spectrometry to systematically identify the RNA-binding proteins (RBPs) that are bound to the 3’UTR of p27 mRNAs in CP-treated versus non-treated cells in vivo. We found that 24 proteins, most of them known RBPs such HuR, hNRNPD, changed their association with p27 mRNA upon CP treatement. Furthermore, knock-down of a subset of the identified RBPs led to the inhibition of the CP-induced increase of p27 mRNA levels. In conclusion, these results highlight substantial rearrangement between RBPs and p27 mRNA upon CP treatment and corroborate the importance of post-transcriptional control in cellular drug response.