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Induction of endogenous Bcl-xS through the control of Bcl-x pre-mRNA splicing by antisense oligonucleotides
J K Taylor1, Q Q Zhang, J R Wyatt
1Department of Pharmacology, Isis Pharmaceuticals, Carlsbad, CA 92008, USA.
Abstract:
Resistance to apoptosis, which plays an important role in tumors that are refractory to chemotherapy, is regulated by the ratio of antiapoptotic to proapoptotic proteins. By manipulating levels of these proteins, cells can become sensitized to undergo apoptosis in response to chemotherapeutic agents. Alternative splicing of the bcl-x gene gives rise to two proteins with antagonistic functions: Bcl-xL, a well-characterized antiapoptotic protein, and Bcl-xS, a proapoptotic protein. We show here that altering the ratio of Bcl-xL to Bcl-xS in the cell using an antisense oligonucleotide permitted cells to be sensitized to undergo apoptosis in response to ultraviolet B radiation and chemotherapeutic drug treatment. These results demonstrate the ability of a chemically modified oligonucleotide to alter splice site selection in an endogenous gene and illustrate a powerful tool to regulate cell survival.
Insights
This study shows that altering the ratio of Bcl-xL to Bcl-xS proteins using antisense oligonucleotides can sensitize cancer cells to apoptosis. This approach offers a new strategy for enhancing chemotherapy and radiation treatment effectiveness.
Area of Science:
- Molecular Biology
- Cancer Research
- Biochemistry
Background:
- Apoptosis resistance is a key challenge in chemotherapy for tumors.
- The balance of antiapoptotic (e.g., Bcl-xL) and proapoptotic (e.g., Bcl-xS) proteins regulates apoptosis.
- Alternative splicing of the bcl-x gene produces these antagonistic proteins.
Purpose of the Study:
- To investigate if manipulating the Bcl-xL/Bcl-xS ratio can sensitize cells to apoptosis.
- To demonstrate the efficacy of antisense oligonucleotides in altering splice site selection for therapeutic potential.
Main Methods:
- Utilized antisense oligonucleotides to target and modify the alternative splicing of the bcl-x gene.
- Exposed treated cells to ultraviolet B radiation and chemotherapeutic drugs.
- Assessed cellular sensitivity to apoptosis.
Main Results:
- Altering the Bcl-xL to Bcl-xS ratio via antisense oligonucleotides sensitized cells to apoptosis.
- This sensitization was observed in response to both ultraviolet B radiation and chemotherapy.
- Demonstrated successful modification of splice site selection for an endogenous gene.
Conclusions:
- Antisense oligonucleotides can effectively modulate the Bcl-xL/Bcl-xS ratio, impacting cell survival.
- This strategy represents a powerful tool for regulating apoptosis and potentially overcoming chemotherapy resistance.
- The findings highlight a novel therapeutic approach for enhancing cancer treatment outcomes.