Chemosensitization of bladder carcinoma cells by bcl-xL antisense oligonucleotides.
OBJECTIVE
We investigated antisense inhibition of anti-apoptotic bcl-xL and bcl-2 proteins to increase chemosensitization in the T24 and 5637 bladder carcinoma cell lines.


METHODS
A T24 bladder carcinoma cell line stably over expressing bcl-xL protein was constructed. Apoptosis by cytotoxic agents was estimated by cell cycle analysis and Annexin V binding. To eliminate bcl-xL expression T24 and 5637 cells were treated with C5-propynylated and 2'-O-methylribo-oligonucleotides. Levels of protein and messenger RNA were measured by Western and Northern blot analysis. Cell viability after combined treatment with oligonucleotides and various cytotoxic agents was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and evaluated statistically by Student's 2-sample t test.


RESULTS
Forced over expression of bcl-xL protein desensitized the T24 bladder carcinoma cell line to cytotoxic agents. C5-propynylated and 2'-O-methylribo-oligonucleotides down-regulated bcl-xL protein expression in the T24 and 5637 cell lines, and increased their sensitivity to cytotoxic agents. The efficiency of antisense down-regulation of bcl-xL protein expression depended on the type of delivery agent.


CONCLUSIONS
Antisense down-regulation of bcl-xL protein sensitizes bladder carcinoma cells to cytotoxic agents. However, it is possible that cellular chemosensitization results from a combination of effects, including nonsequence specificity, irrelevant cleavage and effects of the carriers combined with the specific antisense effects.
Lebedeva
I
I
Departments of Medicine and Pharmacology, Columbia University, New York, New York, USA.
Raffo
A
A
Rando
R
R
Ojwang
J
J
Cossum
P
P
Stein
C A
CA
D017209:Apoptosis; D002277:Carcinoma / Q000188:drug therapy; D002460:Cell Line; D015536:Down-Regulation / Q000502:physiology; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis / Q000502:physiology*; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy; D051020:bcl-X Protein
D016376:Oligonucleotides, Antisense; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein