Abstract 14257: Ribosome-Profiling Reveals Translational Control of SND1 as a Determinant of Endothelial Homeostasis in a hiPSC Model of Sunitinib-Induced Vascular Dysfunction

Introduction: The advent of tyrosine kinase inhibitors in cancer therapies has contributed towards the lowered mortality rate from cancer deaths; however, resulting vascular toxicity from such drugs increases the risk for fatal heart disease in cancer survivors. Thus, a better understanding of the mechanisms related to adverse cardiovascular effects is needed to improve mortality rates in cancer survivors. Hypothesis: The objective of this study is to identify previously unrecognized molecular targets that are regulated at a translational level which may contribute to sunitinib-induced vascular toxicity. Methods and Results: A human induced pluripotent stem cell-derived endothelial cells (hiPSC-EC) model of sunitinib-induced vascular dysfunction was established. Ribosome profiling which allows the selective sequencing of translated RNA regions identified Staphylococcal nuclease domain-containing protein 1 (SND1) as a translationally-repressed gene caused by sunitinib exposure. Mechanistically, we identified that sunitinib repressed SND1 by inhibiting mTOR which in turn dephosphorylates 4E-BP. Double-knockdown of 4E-BP1/2 reversed sunitinib-induced repression of SND1. Loss-of-function studies revealed that SND1 inhibition led to endothelial dysfunction as measured by reduced cell viability, impaired angiogenic capability, and reduced wound healing; effects which were blunted in reciprocal SND1 gain-of-function studies in the presence of sunitinib treatment. Furthermore, our results revealed that SND1 transcriptionally regulates UBC13, an E2-conjugating enzyme that mediates K63-linked ubiquitination. Pharmacological inhibition of UBC13 also led to endothelial dysfunction similar to the detrimental effects of sunitinib or SND1 inhibition. Conclusions: Our study demonstrates that translational control of SND1 which acts through UBC13 is a previously unidentified mechanism that can potentially be manipulated for therapeutic benefits to reduce sunitinib-induced vascular toxicity.