Quantifying single-cell ERK dynamics in colorectal cancer organoids reveals EGFR as an amplifier of oncogenic MAPK...

Area of Science:

• Oncology
• Molecular Biology
• Cancer Signaling

Background:

• Direct targeting of the mitogen-activated protein kinase (MAPK) pathway, specifically extracellular-regulated kinase (ERK) activation, has been clinically unsuccessful for KRAS and BRAF mutant colorectal cancer (CRC).
• Combination therapies involving epidermal growth factor receptor (EGFR) inhibition have shown promising results in treating these CRC subtypes.

Purpose of the Study:

• To elucidate the interplay between epidermal growth factor (EGF) signaling and ERK activation in KRAS and BRAF mutant colorectal cancer (CRC).
• To understand the mechanistic basis for the efficacy of EGFR inhibitors in combination therapies for CRC.

Main Methods:

• Utilized patient-derived organoids (PDOs) from KRAS and BRAF mutant CRCs, which closely mimic in vivo tumors and treatment responses.
• Established real-time, quantitative drug response assessment in PDOs with single-cell resolution using an improved fluorescence resonance energy transfer (FRET)-based ERK biosensor (EKAREN5).

Main Results:

• Demonstrated that oncogene-driven signaling is significantly limited without EGFR activity and insufficient for full proliferative potential in CRC.
• Showed that upstream EGFR activity rigorously amplifies signal transduction efficiency in KRAS or BRAF mutant MAPK pathways in both PDOs and in vivo models.
• Confirmed that EGFR activity is crucial for sustaining oncogenic signaling and proliferation in KRAS/BRAF mutant CRC.

Conclusions:

• EGFR activity is essential for amplifying MAPK pathway signaling in KRAS and BRAF mutant colorectal cancer.
• This mechanistic understanding explains the effectiveness of EGFR inhibitors in combination therapies for treating KRAS and BRAF mutant CRC.