The effect of antisense Bcl-2 oligonucleotides on Bcl-2 protein expression and apoptosis in human bladder transitional cell carcinoma.
OBJECTIVE
Bcl-2 is an important determinant of transitional cell carcinoma of the bladder recurrence and progression as well as a factor in patient response to chemotherapy or radiotherapy. We determined Bcl-2 down-regulation after antisense oligonucleotide therapy and synergism with mitomycin C in transitional cell carcinoma of the bladder.


METHODS
Bcl-2 protein was quantified using flow cytometry and immunohistochemistry in 4 bladder cancer cell lines, in bladder washings from 6 patients with carcinoma in situ and in 16 patient tumor samples. The synergistic effects of antisense oligonucleotides G3139 and 2009, and mitomycin C were investigated in 4 cell lines, while 2009 down-regulation was examined in 20 tumor explants in an ex vivo model.


RESULTS
Bcl-2 protein expression was found in all 4 cell lines and in 5 of the 6 cell populations derived from patients with carcinoma in situ. Of the 16 tumors 7 were classified positive by frozen section immunohistochemistry and quantitative flow cytometry. G3139 and 2009 down-regulated Bcl-2 protein expression in all 4 cell lines and 2009 down-regulated Bcl-2 protein expression in half of the Bcl-2 positive tumor specimens. There was only evidence in 1 cell line, T24/83, that Bcl-2 protein expression down-regulation enhanced mitomycin C induced apoptotic cell death.


CONCLUSIONS
Bcl-2 was expressed in a significant proportion of bladder tumors and in carcinoma in situ. Therefore, antisense oligonucleotides represent a viable strategy for Bcl-2 protein down-regulation. However, it may not always translate into an increased level of mitomycin C induced apoptosis in transitional cell carcinoma of the bladder.
Duggan
B J
BJ
Uro-Oncology Research Group, Cancer Research Centre, Queen's University Belfast, Belfast, Northern Ireland, UK.
Maxwell
P
P
Kelly
J D
JD
Canning
P
P
Anderson
N H
NH
Keane
P F
PF
Johnston
S R
SR
Williamson
K E
KE
D017209:Apoptosis / Q000235:genetics*; D002295:Carcinoma, Transitional Cell / Q000235:genetics*; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D019254:Genes, bcl-2 / Q000235:genetics*; D006801:Humans; D016685:Mitomycin / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000187:drug effects / Q000235:genetics*; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000235:genetics*
D016376:Oligonucleotides, Antisense; D016685:Mitomycin