Mutation of genes affecting the RAS pathway is common in childhood acute lymphoblastic leukemia

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• The RAS-RAF-MEK-ERK signaling pathway is crucial for cell growth and survival.
• Deregulation of this pathway, often due to mutations in genes like NRAS, KRAS2, FLT3, PTPN11, and BRAF, is implicated in various cancers, including acute lymphoblastic leukemia (ALL).

Purpose of the Study:

• To conduct a comprehensive mutational screen of key genes within the RAS-RAF-MEK-ERK pathway in a large cohort of childhood ALL (cALL) cases.
• To determine the frequency and significance of these mutations at diagnosis and disease recurrence.
• To investigate the association of these mutations with pathway activation and potential therapeutic vulnerabilities.

Main Methods:

• Comprehensive mutational screening of key exons in NRAS, KRAS2, FLT3, PTPN11, and BRAF genes.
• Utilized denaturing high-performance liquid chromatography (DHPLC) for sensitive mutation detection.
• Employed allele-specific PCR to detect low-level mutations at diagnosis in matched presentation/relapse samples.
• Assessed ERK activation and cytotoxicity to MEK-ERK inhibitors in primary samples.

Main Results:

• Somatic mutations deregulating the RAS-RAF-MEK-ERK pathway are frequent genetic aberrations in cALL, present in 35% of diagnostic and 25% of relapse samples.
• Mutations predominant at relapse were often detectable at very low levels at diagnosis, suggesting their role in disease progression.
• Mutations were associated with activated ERK signaling and differential sensitivity to MEK-ERK inhibitors in some patients.

Conclusions:

• RAS-RAF-MEK-ERK pathway mutations are a common and significant genetic event in cALL.
• These mutations are implicated in disease progression and may serve as predictive markers.
• Inhibitors targeting the MEK-ERK pathway represent a potential novel therapeutic strategy for cALL, particularly in relapsed disease.