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Bcl-2 mRNA-targeted ribozymes: effects on programmed cell death in chronic myelogenous leukemia cell lines
S Scheid1, M Heinzinger, C F Waller
1Department of Hematology/Oncology, University Medical Center Freiburg, Germany.
Abstract:
We used synthetic RNA transcripts to prove the cleavage capability of ribozymes targeted against bcl-2-related RNAs. No cleavage occurred when control oligonucliotides were used. To assess the functional role of the specific ribozymes in chronic myelogenous leukemia (CML) cell lines we cultured K562, BV173, and Daudi cells for 48 h after lipofection with 10 microM oligonucleotide. An increase in apoptotic cells, dependent on ribozyme specificity, was shown in BV173 cells. This finding was underlined by the typical morphological changes, but there is no correlation with regard to the level of bcl-2 protein expressed. Though bcl-2 appears to interfere with cell death in myeloid cells, bcl-2-targeted ribozymes do not induce programmed cell death (PCD) by reducing bcl-2 protein levels, but rather by a presently unknown mechanism.
Insights
Specific ribozymes targeting bcl-2 related RNA can induce apoptosis in chronic myelogenous leukemia (CML) cells. This programmed cell death (PCD) occurs through an unknown mechanism, not by reducing bcl-2 protein levels.
Area of Science:
- Molecular Biology
- Biochemistry
- Cancer Research
Background:
- The bcl-2 protein is implicated in cell death regulation, particularly in myeloid cells.
- Ribozymes offer a potential therapeutic strategy for targeting specific RNA molecules.
Purpose of the Study:
- To investigate the cleavage capability of ribozymes against bcl-2-related RNAs.
- To assess the functional role of these ribozymes in inducing apoptosis in chronic myelogenous leukemia (CML) cell lines.
Main Methods:
- Utilized synthetic RNA transcripts to test ribozyme cleavage activity.
- Cultured K562, BV173, and Daudi CML cell lines following lipofection with ribozymes.
- Assessed apoptosis induction and morphological changes in treated cells.
Main Results:
- Ribozymes demonstrated specific cleavage of target bcl-2-related RNAs.
- An increase in apoptotic cells was observed in BV173 cells, correlating with ribozyme specificity.
- Morphological changes indicative of apoptosis were noted, but without a direct correlation to bcl-2 protein levels.
Conclusions:
- bcl-2-targeted ribozymes can induce programmed cell death (PCD) in CML cells.
- The mechanism of PCD induction by these ribozymes is not mediated by reducing bcl-2 protein levels and remains to be elucidated.
- bcl-2 may interfere with cell death in myeloid cells, but its direct downregulation is not the primary pathway for ribozyme-induced apoptosis.