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Suppression of BCL2 by Antisense Oligonucleotides and Compensation by Non-Targeted Genes May Enhance Tumor
Marvin Rubenstein1, Courtney M P Hollowell2, Patrick Guinan3
1Division of Cellular Biology, Hektoen Institute for Medical Research, Chicago, IL, U.S.A. Division of Urology, Stroger Hospital of Cook County, Chicago, IL, U.S.A. Department of Biochemistry, Rush University Medical Center, Chicago, IL, U.S.A. Department of Urology, Rush University Medical Center, Chicago, IL, U.S.A. DrMarv@Prodigy.net.
Abstract:
Antisense oligonucleotides have been used to target regulatory proteins in both in vivo and in vitro models of prostate cancer. Our previous studies showed that oligonucleotide-treated LNCaP prostate cancer cells compensate for diminished expression of B-cell chronic lymphocytic leukemia/lymphoma 2 (BCL2), an apoptosis inhibitor, by suppressing the expression of caspase-3 (an apoptosis promoter) while enhancing that of serine/threonine protein kinase (AKT1) (another apoptosis inhibitor). In addition, we found an enhanced expression of the androgen receptor (AR), its p300 and interleukin-6 (IL6) co-activators, polymerase transcription mediator (MED12), and growth-regulating signal transducer (STAT3). The net result was an altered pattern of gene expression often associated with more aggressive and proliferative tumors. To further evaluate adaptive compensatory mechanisms related to tumor resistance, aggression and proliferation, herein we evaluated the level of expression of a proliferation antigen (KI-67) and mitosis-regulating cyclins (B1 and D1). Compared to the relative levels of compensation detailed above, we found the expression of KI-67 to be statistically the most enhanced non-targeted protein yet identified in compensation for suppression of BCL2. Expression of cyclin D1 was also significantly enhanced, although to a much lesser extent. As a result, we propose that oligonucleotide-mediated treatment could be more effective when directed towards KI-67 and BCL2. This could be accomplished by dual monospecific targeting KI-67 and BCL2, or with a bispecific (or proposed multispecific) oligonucleotide simultaneously targeting both.
Insights
Antisense oligonucleotides targeting B-cell chronic lymphocytic leukemia/lymphoma 2 (BCL2) in prostate cancer cells increase proliferation markers like KI-67. Targeting both KI-67 and BCL2 may improve treatment efficacy.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Therapeutics
Background:
- Antisense oligonucleotides (ASOs) are investigated for targeting regulatory proteins in prostate cancer.
- Previous studies revealed compensatory mechanisms in ASO-treated LNCaP cells, including altered apoptosis regulators and co-activator expression.
- These adaptive responses can lead to increased tumor aggression and proliferation.
Purpose of the Study:
- To evaluate adaptive compensatory mechanisms in prostate cancer cells treated with ASOs targeting BCL2.
- To assess the expression of proliferation markers, specifically KI-67 and cyclins B1 and D1.
- To identify potential new therapeutic targets for enhanced ASO treatment efficacy.
Main Methods:
- In vitro analysis of LNCaP prostate cancer cells treated with antisense oligonucleotides.
- Quantitative assessment of B-cell chronic lymphocytic leukemia/lymphoma 2 (BCL2) expression.
- Measurement of apoptosis-related proteins (caspase-3) and apoptosis inhibitors (AKT1).
- Evaluation of co-activators (p300, MED12), signaling transducers (STAT3), and proliferation markers (KI-67, cyclins B1 and D1).
Main Results:
- ASO treatment targeting BCL2 led to significant upregulation of proliferation antigen KI-67, the most enhanced non-targeted protein observed.
- Expression of cyclin D1 was also significantly enhanced, though to a lesser extent than KI-67.
- Compensatory mechanisms resulted in gene expression patterns associated with more aggressive and proliferative tumors.
Conclusions:
- KI-67 is a highly responsive proliferation marker in compensatory pathways following BCL2 suppression.
- Dual targeting of KI-67 and BCL2, potentially via multispecific oligonucleotides, may offer a more effective therapeutic strategy.
- This approach could overcome adaptive resistance mechanisms and improve outcomes in prostate cancer treatment.
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