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Quantitative analysis of survivin protein expression and its therapeutic depletion by an antisense oligonucleotide in
Anna L Olsen1, Joanne M Davies, Louise Medley
1Department of Oncology, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.
Abstract:
RNA-directed antisense and interference therapeutics are a promising treatment option for cancer. The demonstration of depletion of target proteins within human tumors in vivo using validated methodology will be a key to the application of this technology. Here, we present a flow cytometric-based approach to quantitatively determine protein levels in solid tumor material derived by fiber optic brushing (FOB) of non-small cell lung cancer (NSCLC) patients. Focusing upon the survivin protein, and its depletion by an antisense oligonucleotide (ASO) (LY2181308), we show that we can robustly identify a subpopulation of survivin positive tumor cells in FOB samples, and, moreover, detect survivin depletion in tumor samples from a patient treated with LY2181308. Survivin depletion appears to be a result of treatment with this ASO, because a tumor treated with conventional cytotoxic chemotherapy did not exhibit a decreased percentage of survivin positive cells. Our approach is likely to be broadly applicable to, and useful for, the quantification of protein levels in tumor samples obtained as part of clinical trials and studies, facilitating the proof-of-principle testing of novel targeted therapies.
Insights
We developed a flow cytometry method to measure protein levels in non-small cell lung cancer (NSCLC) tumors. This technique successfully demonstrated survivin protein depletion by an antisense oligonucleotide (ASO) therapy.
Area of Science:
- Oncology
- Molecular Biology
- Biotechnology
Background:
- RNA-directed therapeutics, including antisense oligonucleotides (ASOs), show promise for cancer treatment.
- Validating target protein depletion in vivo is crucial for the clinical application of these novel therapies.
Purpose of the Study:
- To present a flow cytometry-based method for quantifying protein levels in solid tumor samples.
- To demonstrate the utility of this method in assessing the efficacy of an ASO targeting survivin in non-small cell lung cancer (NSCLC).
Main Methods:
- Utilized fiber optic brushing (FOB) to obtain solid tumor material from NSCLC patients.
- Employed flow cytometry to quantitatively determine protein levels, focusing on survivin.
- Assessed survivin depletion in tumor samples from a patient treated with the ASO LY2181308.
Main Results:
- Successfully identified a subpopulation of survivin-positive tumor cells in FOB samples.
- Quantitatively detected survivin depletion in tumor samples following treatment with the ASO LY2181308.
- Observed no significant decrease in survivin-positive cells in a tumor treated with conventional chemotherapy, suggesting ASO-specific depletion.
Conclusions:
- The developed flow cytometry approach enables robust quantification of protein levels in FOB-derived tumor samples.
- This methodology facilitates the in vivo proof-of-principle testing of novel targeted therapies, such as ASOs, in clinical studies.
- The findings support the potential of RNA-directed therapies for cancer treatment by demonstrating target engagement and protein modulation.