Cancer Mutations in FGFR2 Prevent a Negative Feedback Loop Mediated by the ERK1/2 Pathway

Area of Science:

• Cellular signaling pathways
• Cancer biology
• Receptor tyrosine kinases

Background:

• Receptor tyrosine kinases (RTKs), like Fibroblast Growth Factor Receptor 2 (FGFR2), tightly regulate cellular functions.
• Uncontrolled RTK signaling and FGFR2 deregulation are implicated in tumor progression and cancer development.
• Activating mutations in FGFR2 are frequently observed in various cancer types.

Purpose of the Study:

• To identify and characterize a negative feedback mechanism regulating FGFR2 signaling.
• To investigate the role of the Ras/MAPK pathway in controlling FGFR2 activity.
• To determine the impact of FGFR2 mutations on signaling and cellular behavior.

Main Methods:

• Investigated the interaction between FGFR2 and the Ras/MAPK pathway (Ras-Raf-MEK1/2-ERK1/2).
• Utilized MEK1/2 inhibitors to assess pathway modulation.
• Performed site-directed mutagenesis, substituting serine 780 (S780) in FGFR2 with alanine or leucine.
• Assessed cell migration in cells expressing wild-type and mutated FGFR2.

Main Results:

• Inhibition of the Ras/MAPK pathway using a MEK1/2 inhibitor led to increased FGFR2 signaling.
• Substitution of S780 in FGFR2 with alanine or leucine resulted in enhanced FGFR2 signaling.
• Cells expressing S780-mutated FGFR2 exhibited increased migration compared to wild-type.
• ERK1/2-mediated phosphorylation of S780 in FGFR2 was identified as a negative feedback mechanism.

Conclusions:

• The ERK1/2-mediated phosphorylation of S780 in FGFR2 acts as a crucial negative feedback loop.
• Inactivation of this feedback loop, through mutations or truncation of S780, contributes to FGFR2 hyperactivation in cancer.
• This hyperactivation of FGFR2 signaling likely promotes increased invasive properties of cancer cells.