Codon-specific translation reprogramming promotes resistance to targeted therapy

Area of Science:

• Molecular Biology
• Oncology
• Biochemistry

Background:

• mRNA translation reprogramming is implicated in cancer development and drug resistance.
• The precise molecular mechanisms underlying translation reprogramming remain largely unknown.
• Wobble tRNA modifications are essential for accurate codon decoding during protein synthesis.

Purpose of the Study:

• To investigate the role of wobble uridine 34 (U34) tRNA modifying enzymes in BRAF V600E-driven melanoma.
• To explore the involvement of U34 enzymes in therapeutic resistance to MAPK inhibitors.
• To elucidate the mechanistic link between U34 enzymes, protein synthesis, and melanoma cell survival.

Main Methods:

• Analysis of U34 enzyme expression in BRAF V600E melanoma models.
• Assessment of cell viability upon concurrent inhibition of MAPK signaling and U34 enzymes (ELP3, CTU1, CTU2).
• Investigation of PI3K pathway activation and its effect on U34 enzyme expression.
• Examination of U34 enzyme-mediated regulation of HIF1A mRNA translation and HIF1α protein levels.

Main Results:

• BRAF V600E melanoma cells exhibit dependence on U34 enzymes for survival.
• Combined inhibition of MAPK signaling and U34 enzymes demonstrates synergistic cytotoxicity.
• PI3K pathway activation, a resistance mechanism, significantly upregulates U34 enzyme expression.
• U34 enzymes promote glycolysis in melanoma by regulating HIF1A translation and maintaining HIF1α protein levels.

Conclusions:

• U34 enzymes are critical mediators of protein synthesis rewiring in BRAF V600E melanoma.
• Targeting U34 enzymes, in combination with MAPK inhibitors, presents a potential therapeutic strategy for melanoma.
• High levels of U34 enzymes and HIF1α are associated with acquired resistance to anti-BRAF therapy, highlighting their role in promoting melanoma cell survival and therapeutic resistance.