The effect of antisense Bcl-2 oligonucleotides on Bcl-2 protein expression and apoptosis in human bladder transitional cell carcinoma.
ABSTRACT 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.
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.
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.
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.
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ABSTRACT: INTRODUCTION: Overexpression of antiapoptotic B-cell lymphoma (Bcl-2) proteins confers the dysregulation of apoptosis and results in drug resistance in a variety of cancers, including those of the genitourinary tract. Inhibitors that target prosurvival Bcl-2 proteins are in preclinical and clinical development. The objective of this review is to assess the involvement of Bcl-2 proteins as well as the preclinical and clinical activity of Bcl-2 inhibitors under evaluation for genitourinary neoplasms. MATERIALS AND METHODS: PubMed was used with both medical subject heading terms and free search to identify the relevant literature. Information on clinical trials was obtained using http://Clincaltrials.gov, EU Clinical Trials Register, and meeting abstracts of the American Society of Clinical Oncology. RESULTS: To date, 2 Bcl-2 inhibitors have been evaluated in clinical trials for genitourinary tumors (oblimersen and AT-101 (R-(-)-gossypol)). Both agents demonstrated some success in early stages of development, but their clinical activity did not meet expectations. Preclinical studies are under way for other Bcl-2 inhibitors including ABT-737, HA14-1, and Bcl-2 homology 3 inhibitors. CONCLUSION: Antiapoptotic Bcl-2 proteins are potential molecular targets in genitourinary cancers. Bcl-2 inhibitors might be effective as single agents or in combination with conventional therapies. However, the biology of the Bcl-2 family in genitourinary cancers remains poorly understood and robust preclinical studies are needed to inform clinical development. Such studies should aim to identify: (1) pharmacodynamic markers that could help guide patient selection for treatment with Bcl-2 inhibitors, and (2) optimal combinations of Bcl-2 inhibitors with other anticancer agents for future clinical investigation.Clinical Genitourinary Cancer 10/2012; · 1.43 Impact Factor
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ABSTRACT: High-risk superficial urothelial carcinoma of the bladder (UCB) is commonly treated with intravesical bacillus Calmette-Guerin (BCG), but with significant side effects. We recently showed that the tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) exhibited high therapeutic potential against UCB cells and with only limited toxic effects in normal cells. However, many cancer cells are refractory to TRAIL during monotherapy. Therefore, our experimental aim was to develop combinatorial approaches with other pro- apoptotic agents to reactivate apoptosis in resistant phenotypes. We demonstrate that UCB cells varied in their response to TRAIL, and the effect was caspase-dependent (reduced or abrogated by pre-incubation of cells with caspase-inhibitor peptides). In contrast wortmannin, a PI3K/Akt inhibitor, enhanced the TRAIL effect. Furthermore, combination therapy of TRAIL with low dose gemcitabine markedly enhanced UCB cell response (except in the TRAIL-resistant HT1376 cell line). The enhanced response was both time- and concentration-dependent and asymptotic at gemcitabine concentration >1 µmol/l. To define the mechanisms underlying gemcitabine-augmented TRAIL action, we evaluated the expression of several proteins regulating the apoptotic pathway. Gemcitabine-augmented TRAIL effect was associated with inhibition of the Bcl-2 protein (intrinsic signalling) along with activation of the caspase (extrinsic) cascade. The combined maximal stimulation of both the intrinsic and extrinsic signalling pathways also appeared to overcome the survival (PI3K/Akt) pathway as evident by the lack of response to wortmannin. Our semisolid multicellular-spheroid model showed that TRAIL and gemcitabine selectively caused UCB cells to undergo apoptosis without affecting normal cells, and both appeared to penetrate deeply enough to allow for combination intravesical therapy.International Journal of Oncology 07/2011; 39(1):61-71. · 2.66 Impact Factor
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