Abstract
Purpose :
Uveal melanoma (UM) arises from melanocytes in the eye and is distinct from skin melanoma. Half of these patients succumb to metastatic disease in the liver. There is currently no approved therapy for metastatic UM (mUM). Experimental therapies have not shown promising outcomes, with poor response to the targeted and immune therapies. There is an urgent need for new therapeutic strategies for mUM patients. We have previously shown upregulated Oxidative Phosphorylation (OXPHOS) effectors in mUM. In this study we aimed to target them in the mitochondria using Imipridones, inducers of the mitochondrial protease ClpP. ClpP controls the degradation of the mitochondrial OXPHOS proteins and regulates their level in the cell.
Methods :
We tested the effect of imipridones (ONC201, 206,212) on UM cell survival in in vitro cell survival assays and also on the levels of SDHA, SDHB and other OXPHOS effectors using western blots. We determined the effect of imipridone treatment on proliferation, apoptotic and integrated stress response (ISR) pathway markers from UM cells. We studied the global proteomic and metabolomic profile of UM cells with imipridone-treatment using RPPA analyses and mass spectrometry-based metabolomics profiling respectively.
Results :
The imipridones blocked UM cell survival in all UM cell lines tested. SDHA and SDHB protein levels were significantly reduced in imipridone-treated UM cells. The phosphorylation of AMPK increased post treatment, signaling a metabolic stress in the treated cells. Apoptosis was induced, as shown by increased processing of PARP as well as Caspases 9 and 3. ISR markers were also induced post treatment with imipridones. A global metabolic profile of cells post treatment showed reduction in protein biosynthesis pathways and alteration of lipid metabolism.
Conclusions :
Treatment with imirpidones reduced UM cell survival, induced apoptosis, ISR and metabolic stress on UM cells. Finally, protein biosynthesis and lipid metabolism were affected with treatment. Taken together, our data show imipridones can target metabolic vulnerabilities of metastatic UM due to elevated mitochondrial OXPHOS and control cell growth. Appropriate validation of these data in a suitable in vivo model can lead to a clinical study in mUM patients to develop new therapeutic avenues.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.