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Antisense Bcl-2 oligonucleotide uptake in human transitional cell carcinoma
B J Duggan1, F E Cotter, J D Kelly
1Uro-Oncology Research Group, Cancer Research Centre, Department of Pathology, The Queen's University Belfast, Belfast, UK. b.duggan@gub.ac.uk
European Urology
|January 24, 2002
Summary
Antisense Bcl-2 oligonucleotides show good uptake in superficial bladder cancer cells. However, variable tumor cell uptake necessitates careful consideration for drug bioavailability assessments.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Antisense oligonucleotides (AO) are a promising therapeutic strategy for downregulating specific protein expression, such as Bcl-2, in various cancers.
- Effective delivery and cellular uptake of AO are critical for achieving therapeutic efficacy in tumor treatment.
- Bcl-2 protein plays a significant role in cancer cell survival and resistance to apoptosis.
Purpose of the Study:
- To investigate the cellular uptake of fluorescein isothiocyanate-labeled antisense oligonucleotides (FITC-AO) targeting Bcl-2.
- To evaluate FITC-AO uptake in a bladder tumor cell line (RT4), normal pig urothelium, and human superficial bladder tumors.
- To assess the time-dependent cellular uptake and bioavailability of AO in bladder cancer models.
Main Methods:
- Quantification of FITC-AO, FITC-scrambled, and FITC-sense oligonucleotide uptake in the RT4 cell line using flow cytometry over 24 hours.
- Assessment of FITC-AO uptake in normal pig urothelium via flow cytometry after a 1-hour infusion.
- Evaluation of FITC-AO uptake in ex vivo human superficial bladder tumor samples using fluorescence microscopy and flow cytometry over 24 hours.
Main Results:
- Uptake of FITC-AO, FITC-scrambled, and FITC-sense oligonucleotides was similar in the RT4 cell line.
- Normal pig urothelial cells showed positive staining for FITC-AO in 33-51% of cells.
- All tested human bladder tumor samples demonstrated detectable intracellular FITC-AO, with most showing increased fluorescence intensity plateauing at 16 hours post-infusion.
Conclusions:
- Antisense Bcl-2 oligonucleotides are effectively internalized by superficial bladder cancer cells.
- The heterogeneous cellular uptake observed in tumor samples is a crucial factor to consider when evaluating the bioavailability of these antisense drugs.
- Further research is warranted to optimize AO delivery strategies for consistent therapeutic outcomes in bladder cancer.