Recurrent somatic structural variations contribute to tumorigenesis in pediatric osteosarcoma

Area of Science:

• Genomics
• Oncology
• Molecular Biology

Background:

• Pediatric osteosarcoma presents with numerous somatic chromosomal abnormalities, such as structural variations (SVs) and copy number alterations (CNAs).
• Understanding the comprehensive landscape of somatic mutations is crucial for advancing pediatric osteosarcoma research and treatment strategies.

Purpose of the Study:

• To define the landscape of somatic mutations in pediatric osteosarcoma using whole-genome sequencing.
• To identify recurrently altered genes and pathways in pediatric osteosarcoma.

Main Methods:

• Whole-genome sequencing (WGS) was performed on DNA from 20 pediatric osteosarcoma tumor samples and matched normal tissue (discovery cohort).
• An additional 14 samples were analyzed in a validation cohort.
• Analysis focused on single-nucleotide variations (SNVs), structural variations (SVs), copy number alterations (CNAs), and kataegis.

Main Results:

• Single-nucleotide variations (SNVs) showed kataegis, a pattern of localized hypermutation, in 50% of tumors.
• p53 pathway lesions were identified in all tumors, with nine cases exhibiting translocations in the TP53 gene's first intron.
• Recurrent somatic alterations were found in TP53, RB1, ATRX, and DLG2 genes in 29%-53% of tumors.

Conclusions:

• Whole-genome sequencing is a powerful tool for uncovering recurrent somatic alterations in cancer genomes, including those potentially missed by other methods.
• The identified genetic alterations in pediatric osteosarcoma provide critical insights into tumor biology and potential therapeutic targets.