Highly Specific Inhibition of c-Myc Oncogene Expression through Shifting the G-Quadruplex toward a Triplex Structure

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• G-quadruplexes are implicated in oncogene regulation.
• Current small molecule therapies targeting G-quadruplexes lack sequence specificity, leading to off-target effects.
• There is a need for precise G-quadruplex targeting strategies in cancer therapy.

Purpose of the Study:

• To introduce fold-back triplex-forming oligonucleotides (FTFOs) as sequence-specific alternatives for targeting G-quadruplexes.
• To investigate the mechanism by which FTFOs interact with and modulate G-quadruplex structures.
• To evaluate the efficacy of FTFOs in suppressing oncogene expression and inhibiting cancer cell progression.

Main Methods:

• Design and synthesis of novel FTFOs.
• Physicochemical analyses to characterize FTFO-G-quadruplex interactions.
• Biological assays to assess the impact of FTFOs on oncogene expression (e.g., c-Myc) and cancer cell phenotypes (growth, mobility).

Main Results:

• FTFOs were shown to effectively unfold the c-Myc G-quadruplex structure.
• FTFOs form noncanonical triplexes, blocking G-quadruplex DNA interactions with transcription factors.
• Identified FTFOs reduced c-Myc expression by up to 80% in a Del4 plasmid model.
• Significant impairment of cancer cell growth, confluence, and mobility was observed.
• Endogenous c-Myc expression was also reduced by FTFO treatment.

Conclusions:

• FTFOs represent an innovative, sequence-specific strategy for targeting G-quadruplex structures.
• Triplex formation by FTFOs effectively arrests G-quadruplexes and suppresses oncogene activity.
• FTFOs hold promise as a targeted therapeutic approach for anticancer treatment.