^V600EBRAF Inhibition Induces Cytoprotective Autophagy through AMPK in Thyroid Cancer Cells

Area of Science:

• Molecular oncology
• Cellular signaling pathways
• Cancer therapeutics

Background:

• Autophagy dysregulation is implicated in cancer development.
• BRAF V600E is a key oncogene in thyroid cancer.
• The interplay between BRAF V600E and autophagy requires further elucidation.

Purpose of the Study:

• To investigate the effect of BRAF V600E inhibition on autophagy in thyroid cancer cells.
• To explore the underlying mechanisms regulating autophagy.
• To determine the role of autophagy in thyroid cancer cell survival and response to BRAF inhibition.

Main Methods:

• Utilized BRAF V600E specific inhibitor (PLX4720) and siRNA for gene silencing.
• Analyzed autophagy induction, LKB1-AMPK signaling, mTOR activity, and MEK/ERK pathway.
• Assessed cell viability, apoptosis, and xenograft tumor growth in vivo.

Main Results:

• BRAF V600E inhibition or depletion induced autophagy in thyroid cancer cells.
• This induction involved increased LKB1-AMPK signaling and decreased mTOR activity via MEK/ERK.
• Autophagy blockade sensitized cells to BRAF inhibition and enhanced anti-tumor effects in vivo.

Conclusions:

• BRAF V600E inhibition activates cytoprotective autophagy through the AMPK-ULK1 pathway.
• Autophagy blockade synergistically enhances the efficacy of BRAF V600E inhibitors.
• Targeting the BRAF/LKB1-AMPK-ULK1-autophagy axis presents a promising therapeutic strategy for BRAF V600E-positive thyroid tumors.