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; DOI:10.1016/j.clgc.2012.09.002 · 1.69 Impact Factor
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ABSTRACT: Cisplatin-based chemotherapy is the first‑line treatment for metastatic urothelial cell carcinoma. However, for cisplatin‑resistant cases, no chemotherapeutic agent has been established as a standard of treatment. This study aimed to investigate the synergistic antitumor effect of ginsenoside Rg3 on cisplatin in cisplatin‑resistant bladder cancer cells (T24R2). T24R2 cells were treated with cisplatin and/or ginsenoside Rg3. Cell viability was assessed by the Cell Counting Kit-8 and clonogenic assays. Synergism between ginsenoside Rg3 and cisplatin was determined when the combination index was <1.0. Flow cytometry was used to evaluate the cell cycle distribution. To estimate the changes of proteins associated with the cell cycle and apoptosis following the treatment of ginsenoside Rg3, western blotting and densitometric assays were performed for caspase-3, -8 and -9, cyclin B1, Bcl-2, Bad, p21 and cytochrome c. The Cell Counting Kit-8 and clonogenic assays showed the synergistic antitumor effect of ginsenoside Rg3 on cisplatin, while the combination index was <1.0, confirming the synergism. Cell cycle alterations at the G2/M phase caused by cisplatin were greater after the combination with ginsenoside Rg3. Western blotting and densitometric assay showed that the expression of Bcl-2 was decreased after the combined treatment of ginsenoside Rg3 and cisplatin, whereas the expression of cytochrome c and caspase-3 were increased, suggesting the activation of the intrinsic apoptotic pathway. In conclusion, ginsenoside Rg3 inhibited the proliferation of cisplatin‑resistant bladder cancer cells in a synergistic manner with cisplatin. Activation of the intrinsic apoptotic pathway and the enhancement of cell cycle alterations are possible explanations for this result.Oncology Reports 08/2014; 32(5). DOI:10.3892/or.2014.3452 · 2.19 Impact Factor
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ABSTRACT: Apoptosis, a physiological process of programmed cell death, is disrupted in various malignancies. It has been exploited as an anti-cancer strategy traditionally by inducing DNA damage with chemotherapy and radiotherapy. With an increased understanding of the intrinsic and extrinsic pathways of apoptosis in recent years, novel approaches of targeting the apoptotic pathways have been tested in pre-clinical and clinical models. There are several early phase clinical trials investigating the therapeutic role of pro-apoptotic agents, both as single agents and in combination. In this review, we examine such treatment strategies, detailing the various compounds currently under clinical investigation, their potential roles in cancer therapeutics, and discussing approaches to their optimal use in the clinic.Critical reviews in oncology/hematology 01/2013; DOI:10.1016/j.critrevonc.2013.12.012 · 5.27 Impact Factor