Systems-level consequences of low RAF abundance for EGFR-ERK signaling

Area of Science:

• Cellular signaling pathways
• Cancer biology
• Computational modeling

Background:

• Receptor tyrosine kinases (RTKs) initiate signaling cascades, including the RAF-MEK-ERK pathway, crucial for cell growth and proliferation.
• RAF proteins are key intermediates in this cascade, but their low abundance in some cancer cells presents an unexplored signaling regime.
• The functional consequences of limited RAF abundance on epidermal growth factor receptor (EGFR)-ERK pathway dynamics remain unclear.

Purpose of the Study:

• To investigate the impact of low RAF abundance on EGFR-ERK pathway signaling dynamics using computational models.
• To explore potential signaling bottlenecks and stochastic effects arising from limited RAF protein levels.
• To identify key molecular interactions determining pathway behavior in low-RAF conditions.

Main Methods:

• Development of continuum and stochastic computational models for the EGFR-ERK pathway.
• Analysis of signaling bottlenecks and stochastic RAF dynamics under varying RAF abundance.
• Application of parameter sensitivity and Sloppiness analyses to identify critical signaling determinants.

Main Results:

• Low RAF abundance creates significant signaling bottlenecks between RTKs and ERK, potentially hindering signal propagation.
• Stochastic RAF dynamics can propagate, particularly affecting low-abundance downstream pathway proteins.
• RAF bottlenecks were predicted to impede ERK activation by oncogenic RAS mutants.
• RAS activation and RAS-RAF interactions were identified as critical determinants of signaling in low-RAF settings.

Conclusions:

• Limited RAF abundance represents a common yet understudied signaling regime in cancer.
• RAF bottlenecks can impair EGFR-ERK pathway activation and may influence responses to oncogenic RAS mutations.
• Computational modeling provides a powerful framework for understanding complex signaling dynamics and identifying therapeutic targets.