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Antiproliferative effects of antisense oligonucleotides directed to the RNA of c-myc oncogene
G Degols1, J P Leonetti, N Mechti
1Laboratoire de Biochimie des Proteines, UA CNRS 1191, Université de Montpellier II, France.
Abstract:
Several groups have reported the use of antisense oligonucleotides to inhibit c-myc gene expression and study its biological role. However high concentrations of free oligonucleotides were generally needed. To lower their concentration and stabilize the antisense effect against c-myc, oligonucleotides were covalently linked to poly(L-lysine) and administered in ternary complexes formed with heparin (100 micrograms/ml). A sequence specific growth inhibition was observed at concentrations lower than 1 microM, while oligonucleotide-poly(L-lysine) conjugates alone were inefficient. Similar results occurred with other polyanionic compounds. Inhibition of proliferation was correlated to a reduction of c-myc protein and to a transient decrease in c-myc mRNA level. However, implication of RNase H in this process could not be demonstrated.
Insights
Antisense oligonucleotides targeting c-myc gene expression were stabilized with poly(L-lysine) and heparin. This approach significantly enhanced sequence-specific growth inhibition at lower concentrations, improving therapeutic potential.
Area of Science:
- Molecular Biology
- Gene Regulation
- Oligonucleotide Therapeutics
Background:
- Antisense oligonucleotides (ASOs) are used to inhibit gene expression, including the oncogene c-myc.
- High concentrations of free ASOs are often required for efficacy, limiting their therapeutic application.
- Developing methods to enhance ASO stability and reduce effective concentrations is crucial.
Purpose of the Study:
- To improve the efficacy and reduce the required concentration of antisense oligonucleotides targeting c-myc.
- To investigate the stabilizing effect of poly(L-lysine) and heparin complexation on ASO activity.
- To correlate growth inhibition with changes in c-myc expression at protein and mRNA levels.
Main Methods:
- Covalent linkage of antisense oligonucleotides to poly(L-lysine).
- Formation of ternary complexes with heparin for ASO delivery.
- Assessment of sequence-specific growth inhibition in cancer cells.
- Quantification of c-myc protein and mRNA levels using Western blot and RT-PCR.
Main Results:
- Ternary complexes of ASO-poly(L-lysine)-heparin demonstrated sequence-specific growth inhibition at sub-micromolar concentrations.
- ASO-poly(L-lysine) conjugates alone showed limited efficacy.
- Inhibition of proliferation correlated with reduced c-myc protein and transiently decreased c-myc mRNA.
- No evidence for RNase H involvement in the observed inhibition.
Conclusions:
- Complexation of antisense oligonucleotides with poly(L-lysine) and heparin significantly enhances their ability to inhibit c-myc expression and cell growth.
- This strategy offers a promising approach to lower effective ASO concentrations for therapeutic applications.
- Further research is needed to elucidate the precise mechanism of action, as RNase H does not appear to be involved.