Cellular effects of antisense c-myc oligodeoxynucleotides are delivery dependent

Area of Science:

• Molecular Biology
• Gene Therapy
• Cardiovascular Research

Background:

• The proto-oncogene c-myc is crucial for cell cycle regulation and vascular smooth muscle cell proliferation.
• Antisense oligodeoxynucleotides (AS-ODNs) show potential for inhibiting c-myc expression but face challenges with cellular uptake and stability.
• Current methods like liposome enhancement offer suboptimal delivery and protection for AS-ODNs.

Purpose of the Study:

• To investigate the efficacy of conjugating antisense c-myc oligodeoxynucleotides to lipophilic linkers for enhanced cellular delivery and therapeutic effect.
• To compare the growth inhibitory effects of lipid-conjugated AS-ODNs with unconjugated and liposome-enhanced AS-ODNs.

Main Methods:

• Synthesis of antisense phosphodiester c-myc oligodeoxynucleotides conjugated to lipophilic linkers.
• Treatment of cultured human aortic smooth muscle cells with conjugated and unconjugated AS-ODNs (phosphodiester and phosphorothioate).
• Assessment of cellular incorporation, intracellular retention, c-myc protein expression, and cell growth inhibition.

Main Results:

• Conjugated antisense c-myc phosphodiester oligodeoxynucleotides achieved 47.5% smooth muscle cell growth inhibition after a 24-h exposure.
• Liposome-enhanced, unconjugated AS-ODNs showed lower inhibition rates (24.4% for phosphodiester, 29.5% for phosphorothioate).
• Inhibition of cell growth correlated with suppressed nuclear c-myc protein expression, indicating successful gene silencing.

Conclusions:

• Lipid conjugation significantly enhances cellular incorporation and retention of antisense c-myc oligodeoxynucleotides.
• This approach leads to rapid and sustained inhibition of c-myc expression and prolonged smooth muscle cell growth inhibition.
• Lipid-conjugated AS-ODNs represent a promising strategy for developing effective gene therapies for diseases involving c-myc-driven proliferation.