Abstract 455: Cellular response to oxaliplatin treatment shows altered DNA damage, nucleolar and ribosomal stresses as main altered pathways

Oxaliplatin is a platinum-based drug playing a critical role in the treatment of colorectal carcinoma and various Hodgkin and non-Hodgkin lymphomas. The primary mechanism of action is reported to be DNA damage and double strand breaks response. However, platinum-based drugs are usually very reactive and covalently binds not only to DNA but also to RNA, proteins or glutathione. Concerning very high reactivity of platinum compounds, we have performed whole-cell proteomic profiling on highly chemosensitive CCRF-CEM cell line to identify all possible cellular response mechanisms. For modeling of actual drug response, CCRF-CEM cell line was treated with 5 x IC 50 (29.3 µM) for half-time to caspase activation (240 min). Such cells were analyzed using current high-resolution mass spectrometry. Totally, 4049 proteins were identified over three biological replicates. Among these proteins, 76 were significantly downregulated and 31 significantly upregulated in the whole experiment. Bioinformatic analysis showed nucleolar and ribosomal stress, changes in secretory, mitotic and DNA damage related proteins. These response pathways were confirmed by functional analyses and targeted experiments aimed to expression changes of selected proteins. Results observed in this experiment suggests nucleolar and ribosomal stress as the most abundant stress responses to oxaliplatin treatment at a halftime to apoptosis. Down-regulation of ribosomal proteins indicates stop of ribosome synthesis, which is one kind of response to stress. In such a case, energy saved by stopping ribosome biogenesis could be invested in solving stress conditions. Dysregulated ribosomal proteins are reported activators of p53 as well. In conclusion, oxaliplatin-induced cellular stress caused an acute response at an early stage of the experiment. Acute response stopped ribosomal biosynthesis and reduced the nucleolar size by the currently unknown mechanism. Nucleolar and ribosomal stress then triggers apoptosis in both p53 dependent and independent pathways. This work was supported by Internal Grant of Palacky University in Olomouc (LF_2016_019), Ministry of School, Education and Youth of the Czech Republic (LO1304 and LM2015064) and Technological Agency of the Czech Republic (TE02000058). Citation Format: Tomas Oždian, Dusan Holub, Zuzana Maceckova, Lakshman Varanasi, Gabriela Rylova, Jiři Rehulka, Jana Vaclavkova, Hanus Slavik, Pavel Moudry, Pawel Znojek, Jarmila Stankova, Juan Bautista de Sanctis, Marian Hajduch, Petr Džubak. Cellular response to oxaliplatin treatment shows altered DNA damage, nucleolar and ribosomal stresses as main altered pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 455.