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The Impact of Spliceosome Inhibition in SF3B1-Mutated Uveal Melanoma
Josephine Q N Nguyen1,2, Wojtek Drabarek3, Aïsha M C H J Leeflang1,2
1Department of Ophthalmology, Erasmus MC Cancer Institute, Erasmus MC Medical Center Rotterdam, CA Rotterdam, The Netherlands.
Purpose:
Unfortunately, treatment of patients with uveal melanoma (UM) with metastatic disease is limited. Twenty percent of patients with UM harbor a mutation in the splicing factor gene SF3B1, suggesting that aberrant spliceosome function plays a vital role in tumorigenesis. Splicing inhibitors exploit the preferential sensitivity of spliceosome-compromised leukemic cells to these compounds.
Methods:
We studied the effect of the splicing inhibitor E7107 using two UM cell lines and ex vivo cultured SF3B1- and BAP1-mutated primary UM tumor slices. These UM cell lines and ex vivo tumor slices were exposed for 24 hours to different concentrations of E7107. Tumor slices were stained with hematoxylin and eosin (H&E) and incubated with BAP1, MelanA, MIB-1, and caspase-3 antisera.
Results:
The E7107-exposed UM cell lines exhibited decreased cell viability and increased apoptosis, with the greatest effect on SF3B1-mutated UM cells. A similar effect on UM tumor slices was observed upon exposure to E7107. Additionally, RNA was isolated for differential isoform expression analysis. No significant difference in isoform usage was found genome-wide. However, specific genes were differentially expressed after E7107 treatment in the SF3B1-mutated samples. Moreover, E7107 had the greatest effect on intron retention.
Conclusions:
This study indicates/suggests that mutated SF3B1 UM cells are more sensitive to the splicing inhibitor E7107 than wild-type SF3B1 UM cells.
Insights
Uveal melanoma (UM) cells with SF3B1 mutations show increased sensitivity to the splicing inhibitor E7107. This targeted approach offers potential for treating metastatic uveal melanoma.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Metastatic uveal melanoma (UM) has limited treatment options.
- SF3B1 gene mutations are present in 20% of UM patients, indicating spliceosome dysfunction in tumorigenesis.
- Splicing inhibitors are being explored, leveraging the sensitivity of spliceosome-compromised cells.
Purpose of the Study:
- To investigate the efficacy of the splicing inhibitor E7107 in uveal melanoma.
- To determine if SF3B1-mutated UM cells exhibit differential sensitivity to E7107 compared to wild-type cells.
Main Methods:
- Utilized two UM cell lines and ex vivo primary UM tumor slices (SF3B1- and BAP1-mutated).
- Exposed cells and tumor slices to varying concentrations of E7107 for 24 hours.
- Performed cell viability assays, apoptosis staining (caspase-3), and differential isoform expression analysis via RNA isolation.
Main Results:
- E7107 treatment decreased cell viability and increased apoptosis in UM cell lines, with a pronounced effect on SF3B1-mutated cells.
- Similar sensitivity was observed in ex vivo UM tumor slices.
- While genome-wide isoform usage showed no significant changes, E7107 treatment led to differential gene expression and increased intron retention in SF3B1-mutated samples.
Conclusions:
- SF3B1-mutated uveal melanoma cells are more sensitive to the splicing inhibitor E7107 than wild-type cells.
- E7107 demonstrates potential as a targeted therapy for UM, particularly in patients with SF3B1 mutations.
