Poster abstracts
Poster number 28 submitted by Zac LaRocca-Stravalle
Unveiling the Alternative Splicing Landscape in Hepatoblastoma for the Enhancement of Prognostic and Therapeutic Approaches
Zac LaRocca-Stravalle (Nationwide Childrens Hospital ), Andrea Castaneda (Germans Trias i Pujol Research Institute), Carolina Armengol (Germans Trias i Pujol Research Institute)
Abstract:
Hepatoblastoma (HB), the most common pediatric liver cancer, has a 3-year event-free survival rate above 80% with chemotherapy and surgery, yet outcomes for advanced tumors remain poor. While molecular stratifications based on genomic, transcriptomic, and epigenomic data have been proposed to predict prognosis, the alternative RNA splicing (AS) landscape in HB remains unexplored. Since pediatric cancers, including HB, typically have a low mutational burden but are enriched for AS events, investigating AS could reveal new biomarkers and therapeutic targets.
We used RNA-seq data from 30 matched tumor-normal HB patients (GEO: GSE133039) to perform differential splicing analysis with rMATS. Significant alternative splicing events (ASEs) were further analyzed in R. Between HB and normal liver, we identified 1,875 significant AS events, mostly comprising skipped exons (SE; 55%) and mutually exclusive exons (MXE; 24%). Differential gene expression was assessed using edgeR, and key AS events were validated in HepG2 cells and normal tissue using RT-PCR.
Unsupervised hierarchical clustering using correlation distances revealed two ASE-derived HB subgroups. Cluster 1 (C1) and Cluster 2 (C2) comprised 14 and 15 patients, respectively. C2 was enriched with poor prognostic features, such as high-risk CHIC and PRETEXT stage, elevated AFP serum levels, vascular invasion, multifocality, and decreased survival, as well as molecular associations previously found to predict poor outcomes in HB, including the Epi-CB epigenetic subtype, high 14q32 gene signature expression, and CTNNB1 mutations.
To identify the most prognostic ASEs between clusters, we performed differential splicing analysis between C1 and C2 and examined associations between ASEs and prognostic features. AS of PARD3, GAS5, RPL21, and SNHG1 were among the most predictive of high-risk HB features and poor survival.
These findings suggest that HB tumors can be stratified based on AS profiles with significant clinical implications. This study opens new pathways for the molecular characterization of HB, providing insights into AS mechanisms that could lead to novel biomarkers and therapies.
References:
Aronson, D., et al. (2014). The treatment of hepatoblastoma: Its evolution and the current status as per The siopel trials. Journal of Indian Association of Pediatric Surgeons, 19(4), 201. https://doi.org/10.4103/0971-9261.142001
Carrillo-Reixach, et al. (2020). Epigenetic footprint enables molecular risk stratification of hepatoblastoma with clinical implications. Journal of Hepatology, 73(2), 328–341. https://doi.org/10.1016/j.jhep.2020.03.025
Hooks, K. B., et al. (2018). New insights into diagnosis and therapeutic options for proliferative hepatoblastoma. Hepatology, 68(1), 89–102. https://doi.org/10.1002/hep.29672
Venkataramany, A. S., et al. (2022). Alternative RNA splicing defects in pediatric cancers: New insights in tumorigenesis and potential therapeutic vulnerabilities. Annals of Oncology, 33(6), 578–592. https://doi.org/10.1016/j.annonc.2022.03.011
Keywords: Alternative Splicing, Cancer, Risk Stratification