The effect of antisense Bcl-2 oligonucleotides on Bcl-2 protein expression and apoptosis in human bladder transitional cell carcinoma

Updates on the Pivotal Roles of Mitochondria in Urothelial Carcinoma

Mitochondria are important organelles responsible for energy production, redox homeostasis, oncogenic signaling, cell death, and apoptosis. Deregulated mitochondrial metabolism and biogenesis are often observed during cancer development and progression. Reports have described the crucial roles of mitochondria in urothelial carcinoma (UC), which is a major global health challenge. This review focuses on research advances in the role of mitochondria in UC. Here, we discuss the pathogenic roles of mitochondria in UC and update the mitochondria-targeted therapies. We aim to offer a better understanding of the mitochondria-modulated pathogenesis of UC and hope that this review will allow the development of novel mitochondria-targeted therapies.

Impact of BCL2 polymorphisms on survival in transitional cell carcinoma of the bladder

PURPOSE

To evaluate the impact of three BCL2 single-nucleotide polymorphisms, i.e., c.-938C>A (rs2279115), c.21G>A (rs1801018), and c.*2203A>G (rs4987853) on survival in patients with transitional cell carcinoma of the bladder.

METHODS

We analyzed 179 patients who underwent surgical treatment for bladder cancer at the Clinic of Urology, University Hospital Essen, Germany. Genomic DNA was extracted and genotyped for the polymorphisms. For all polymorphisms, linkage analysis was performed. Kaplan-Meier and Cox regression analyses were used to determine the putative impact of the three polymorphisms on outcome.

RESULTS

c.-938C>A and c.21G>A, but not c.*2203A>G, are in strong linkage disequilibrium (D' 0.96). We found a significant association between c.-938C>A and relapse-free survival (p = 0.024) with an allele dose effect. In the same way, c.21G>A had a significant impact on both relapse-free survival (p = 0.009) and progression-free survival (p = 0.012), as well as a pronounced allele dose effect. Regression analysis proved c.21G>A and c.-938C>A, to be an independent risk factor in univariate and multivariable analyses.

CONCLUSIONS

In our cohort, both c.-938C>A and c.21G>A showed a significant impact on outcome with TCC of the bladder. Due to the linkage disequilibrium of both SNPs, maybe, only one of them could mediate this effect. In multivariable analysis, however, both proved to be independently associated with overall survival. Contrary to other findings which found the c.-938C>A mainly influencing outcome, our data may suggest that the main effect on TCC could be due to the c.21G>A polymorphism.

Molecular mechanisms of apoptosis and roles in cancer development and treatment

Programmed cell death (PCD) or apoptosis is a mechanism which is crucial for all multicellular organisms to control cell proliferation and maintain tissue homeostasis as well as eliminate harmful or unnecessary cells from an organism. Defects in the physiological mechanisms of apoptosis may contribute to different human diseases like cancer. Identification of the mechanisms of apoptosis and its effector proteins as well as the genes responsible for apoptosis has provided a new opportunity to discover and develop novel agents that can increase the sensitivity of cancer cells to undergo apoptosis or reset their apoptotic threshold. These novel targeted therapies include those targeting anti-apoptotic Bcl-2 family members, p53, the extrinsic pathway, FLICE-inhibitory protein (c-FLIP), inhibitor of apoptosis (IAP) proteins, and the caspases. In recent years a number of these novel agents have been assessed in preclinical and clinical trials. In this review, we introduce some of the key regulatory molecules that control the apoptotic pathways, extrinsic and intrinsic death receptors, discuss how defects in apoptotic pathways contribute to cancer, and list several agents being developed to target apoptosis.

Bcl-2 family of proteins as therapeutic targets in genitourinary neoplasms

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.

Silencing of anti-apoptotic transmembrane protein lifeguard sensitizes solid tumor cell lines MCF-7 and SW872 to perifosine-induced cell death activation

Lifeguard (LFG), an anti-apoptotic protein with high expression rates in breast cancer cells, has been identified as a molecule that inhibits death mediated by Fas. The molecular function of LFG and its regulation in the carcinogenesis of human breast and sarcoma cells, however, remains to be elucidated. In the present study, we investigated the ability of LFG expression to inhibit apoptosis induced by the alkyl-phospholipid perifosine. Results showed that LFG was able to be downregulated in selected sarcoma and breast cancer cell lines characterized by high endogenous LFG expression. A decreased LFG expression led to enhanced sensitivity to treatment with an agonistic Fas antibody or treatment with perifosine. Taken together, our findings indicate the role of LFG as an anti-apoptotic protein and provide further evidence of the potential of LFG as a target for the development of novel therapeutic strategies.

Emerging apoptosis agonists for bladder cancer

Bladder cancer is a very common and aggressive tumor entity. Unfortunately, common chemotherapy is not able to cure advanced bladder cancer. Therefore, several attempts have been made to improve the response to chemotherapy. Because changes in apoptotic pathways are frequent events in the development of chemoresistance of malignancies, pro-apoptotic treatment seems promising for the improvement of bladder cancer prognosis. Preclinical data show potential ways for a successful combination of apoptosis agonists with conventional chemotherapy. None of these principles has so far successfully been translated into clinical trials for bladder cancer. This review describes actual studies and future perspectives for apoptotic agonists in bladder cancer.

Novel therapeutics in metastatic bladder cancer

BACKGROUND

Albeit transitional cell carcinoma of the urinary bladder is a chemosensitive neoplasm, metastatic disease is related with poor prognosis and short-term survival data.

OBJECTIVE

Cisplatin-based combination chemotherapy is recognised as the golden standard therapy for patients with inoperable locally advanced or metastatic bladder cancer. However, owing to treatment-related toxicities and short-response durations, novel treatment options or agents, with both enhanced efficacy and tolerability, have been sought.

METHODS

Reviewing the current status and addressing the future of novel anticancer therapeutics in metastatic urinary bladder cancer.

RESULTS/CONCLUSION

Non-platinum, single agents, such as gemcitabine and taxanes, as well as multidrug regimens in doublet or triplet chemotherapeutic combinations are regarded as promising alternatives. Dose intensification of conventional regimens, dose-dense sequential administration of new agents, the use of molecular markers for predicting chemosensitivity and the integration of biologically targeted agents to enhance chemotherapeutic efficacy are promising approaches.

Optimizing chemotherapy for transitional cell carcinoma by application of bcl-2 and bcl-xL antisense oligodeoxynucleotides

OBJECTIVE

Therapy failure after intravesical and systemic chemotherapy for transitional cell carcinoma (TCC) is still high. Antiapoptotic proteins such as Bcl-2 and Bcl-xL have been reported to promote chemoresistance in TCC. Targeting bcl-2 and bcl-xL messenger ribonucleic acid with antisense oligodeoxynucleotides (AS-ODNs) may enhance the cytotoxic effects of chemotherapeutic agents. Therefore, we investigated the effects of bcl-2 and bcl-xL AS-ODNs in combined treatment with conventional and new chemotherapeutic agents to evaluate the cytotoxic effects in comparison to monotreatment.

METHODS AND MATERIALS

Western blot analysis or immunohistochemistry verified Bcl-2 and Bcl-xL expression in a panel of human TCC cell lines that had been monotreated with cisplatin, gemcitabine, mitomycin C, and paclitaxel. In addition, bcl-2 or bcl-xL AS-ODNs were applied in combination with each chemotherapeutic agent. Cell viability was determined using a standard MTT assay and Neubauer hemocytometry.

RESULTS

All cell lines responded to chemotherapeutic monotreatment in a dose-dependent manner. Maximum cell death rates after monotreatment were 47.4% (cisplatin), 39.0% (gemcitabine), 83.4% (mitomycin C), and 54.8% (paclitaxel). After combined treatment with chemotherapy and bcl-2 or bcl-xL AS-ODNs, cell death rates were significantly higher (e.g., 30.3% vs. 87.2% in HT 1197 cells for monotreatment vs. the combination of paclitaxel and bcl-xL AS-ODNs). Three-way analysis of variance revealed that combined treatment had a significant effect on all cell lines.

CONCLUSIONS

Our study confirms that the addition of bcl-2 and bcl-xL AS-ODNs enhances the cytotoxic potential of chemotherapeutic agents in TCC cell lines as a result of combined effects. Further trials in ex vivo and in vivo models have to be performed to promote clinical application in patients.

New agents for treatment of advanced transitional cell carcinoma

The prognosis for any patient with progressive or recurrent invasive transitional cell carcinoma remains poor. In this context, the focus of clinical research in these invasive cancers concentrates on identifying systemic treatment options and new agents in order to improve survival of patients. Cisplatin-based chemotherapy is standard treatment of patients with metastatic urothelial cancer; however, despite regimens as the cisplatin-gemcitabine combination, the overall response rates vary between 40% and 65%, with complete response in 15%-25% with survivals up to 16 months. This survival is frequently achieved with severe and life-threatening side effects. None the less, almost all responding patients relapse within the first year; therefore, the need for development of new and tolerable agents is urgent. This review highlights some new active chemotherapeutic as new platinum compounds (oxaliplatin, lobaplatin), gallium nitrate, ifosfamide, the antifolates piritrexim and pemetrexed (Alimta, LY231514), vinflunine and molecular targeting agents such as farnesyltransferase inhibitors (lonafarnib, R115777, SCH66336), ribozyme (RPI.4610), histone deacetylase inhibitor (CI-994) and monoclonal antibodies (epidermal growth factor receptor, Her 2/neu).

Sensitizing effect of galectin-7 in urothelial cancer to cisplatin through the accumulation of intracellular reactive oxygen species

To improve chemotherapeutic efficacy in urothelial cancer, it is important to identify predictive markers for chemosensitivity as well as possible molecules accelerating cell killing mechanisms. In this study, we assessed the possibility of galectin-7 to accelerate cis-diamminedichloroplatinum (CDDP)-induced cell killing in vitro and also to predict chemosensitivity against CDDP in urothelial cancer patients. The expression of galectin-7 was analyzed in five bladder cancer cell lines with different p53 status after treatment with CDDP. The roles of galectin-7 in chemosensitivity against CDDP were analyzed by transfection of the galectin-7 gene into several of these cell lines. Furthermore, the relationship between the expression of galectin-7 and the response to neoadjuvant chemotherapy was analyzed in 17 human bladder cancer specimens. Exposure to CDDP induced galectin-7 in cell lines with wild-type p53 but not in those with mutated p53. When the galectin-7 gene was transfected into cell lines with mutated p53, the sensitivity to CDDP increased compared with control transfectants. In addition, galectin-7-transfected cells exhibited more accumulation of intracellular reactive oxygen species and activation of c-Jun NH(2)-terminal kinase (JNK) and Bax than control transfectants. SP600125, an inhibitor of JNK, or antioxidant N-acetyl-L-cysteine inhibited the enhancement of chemosensitivity against CDDP by galectin-7 transfection. In clinical samples, the expression levels of galectin-7 were significantly lower in urothelial carcinomas compared with normal urothelium. When chemosensitivity was tested, its expression levels were higher in the chemosensitive group than in the chemoresistant group. Galectin-7 is a candidate for a predictive marker of chemosensitivity against CDDP, and the targeted expression of galectin-7 might overcome the chemoresistance of urothelial cancer.

Synthetic nucleic acids as potential therapeutic tools for treatment of bladder carcinoma

OBJECTIVES

Abnormal gene activation in human tumours including bladder cancers (bCAs) may cause altered proliferation, maturation, and apoptosis as well as development of resistance to therapeutic interventions. Therefore, silencing of abnormally activated genes appears to be a rational approach for specific target-directed and sensitising therapies.

METHODS

Of the available strategies for gene silencing, antisense-based techniques have attracted much attention and are the focus of this review. Putative target genes should be involved in essential tumour-promoting pathways, such as growth signalling, immortalisation, cell cycle regulation, apoptosis, angiogenesis, and development of therapy resistances. This review gives an overview of selected studies performed on bCA-derived cell lines and xenografts reporting down-regulation of potential target genes by antisense-based synthetic nucleic acids such as antisense oligodeoxynucleotides (AS-ODNs) and small interfering RNAs (siRNAs). Effects on proliferation of bCA cells and enhancement of the cytotoxic action of different chemotherapeutics were evaluated.

RESULTS

Knock-down of the selected target genes frequently caused an impairment of growth of different bCA cell lines originating from cell cycle arrest or increased apoptosis. In numerous studies, the pretreatment with AS-ODNs or siRNAs provoked strong enhancement of subsequent chemotherapies, emphasising the effectiveness of these inhibition approaches.

CONCLUSIONS

The application of antisense-based inhibitors in combination with chemotherapeutics might represent an alternative strategy for the adjuvant treatment of superficial bCA. Nevertheless, translation of this technology to the clinic might be hampered by inestimable off-target effects caused by AS-ODNs and their behaviour after intravesical instillation has to be evaluated in preclinical and clinical trials.

Chemosensitization of bladder cancer cells by survivin-directed antisense oligodeoxynucleotides and siRNA

Survivin is known to be overexpressed in numerous tumor types including human bladder cancer and to cause resistance to radiation and chemotherapy. Therefore, we tested the antisense oligodeoxynucleotide AS-SVV286 and the small interfering RNA si-SVV284 to down-regulate survivin in the BCa cell lines EJ28 and 5637 thereby acting as sensitizers for chemotherapy. Pretreatment with these inhibitors followed by chemotherapy caused an enhanced decrease in cell viability. The observed reduction in cell counts associated with increased rates of apoptosis paralleled the degree of reduction of survivin expression that was achieved more efficiently by the siRNA than by the AS-ODN. Nevertheless, both therapy approaches in combination with all tested chemotherapeutics provoked a remarkable inhibition of viability and may serve as suitable additive tools for chemosensitization of bladder cancer cells.

Antisense oligonucleotides in the treatment of bladder cancer

This review examines the role that antisense oligonucleotides play in the treatment of superficial and muscle-invasive bladder cancer. The unique environment of the urinary bladder allows intravesical instillation of antisense oligonucleotides, and researchers have already demonstrated uptake of antisense oligonucleotides in models of bladder cancer. Second, proof of principle has been established by demonstrating downregulation of the antisense target mRNA and protein. Third, and most importantly from a therapeutic perspective, synergy between chemotherapy and antisense oligonucleotides has been shown in bladder cancer models in vitro and in vivo. The collective evidence points to a role for antisense oligonucleotides in the treatment of superficial and muscle-invasive bladder cancer in combination with existing treatment modalities.

Antisense oligodeoxynucleotide therapy for bladder cancer: recent advances and future prospects

Despite remarkable progress in therapeutic options for the management of bladder cancer, it remains a challenge for urologists to achieve successful outcomes in the treatment of both superficial and invasive bladder cancers. In this review, recent advances in the field of antisense oligodeoxynucleotide therapy targeting several genes playing functionally important roles in the progression and recurrence of bladder cancer are summarized. Data showing the synergistic antitumor activities of antisense oligodeoxynucleotide therapy, combined with several treatments, including cytotoxic chemotherapy, radiation and other molecular targeting therapies, are also presented. Finally, the future direction of antisense oligodeoxynucleotide therapy in the therapeutic strategy of bladder cancer is discussed. These findings may help clarify the significance of antisense oligodeoxynucleotide therapy as an attractive alternative to conventional strategies.

Antisense oligonucleotide therapy in the management of bladder cancer

PURPOSE OF REVIEW

In this paper, we will review the recent advances in antisense oligonucleotide therapy in the treatment of superficial bladder cancer. Bladder cancer has an exciting potential as a model to study antisense oligonucleotide therapy because of the ease of accessibility of treatment, ease of diagnosis through biopsy and urine cytology, and direct observation of treatment efficacy through cystoscopy and posttreatment biopsy.

RECENT FINDINGS

We will elaborate on the recent developments in the delivery of antisense oligonucleotide and the implications of these results on the use of antisense oligonucleotide intravesically. We will also discuss recent preclinical in-vitro results of antisense oligonucleotide therapy in different bladder cancer cell lines.

SUMMARY

Recent developments of the in-vitro and animal in-vivo effectiveness of antisense treatment in bladder cancer provide the foundation to pursue future phase I clinical trials. Antisense oligonucleotide technology is a promising tool that may become an effective method of treating bladder cancer.

Apoptosis and chemotherapy for bladder cancer

PURPOSE

We discuss the role of apoptosis, that is gene directed self-destruction of a cell, in the response of bladder transitional cell carcinoma cells to chemotherapy.

MATERIALS AND METHODS

A directed MEDLINE literature search of apoptosis, bladder cancer and chemotherapy was performed to extract relevant information for review. The characteristics of apoptotic cells were defined and the methods in common use to detect these traits is described. The role of the key mediators of the apoptotic process in bladder cancer is discussed in the context of chemosensitivity and disease stage. The importance of the apoptosis induction after chemotherapy is highlighted.

RESULTS

On stimulus by appropriate external or internal signals a cell may alter the expression of genes encoding for proteins associated with the apoptotic process. The development of apoptosis depends on the balance between pro-apoptotic and anti-apoptotic proteins. Key alterations in genes and proteins related to apoptosis within bladder cancer result in a shift away from the default state of apoptosis toward a cell with increased survival properties that is chemoresistant.

CONCLUSIONS

Much current research in bladder cancer is aimed at restoring chemosensitivity by shifting the cell toward a pro-apoptotic phenotype. Successful translation of this work into clinical practice may improve survival in patients in whom prognosis is currently poor.

Current strategies in cancer gene therapy

Cancer gene therapy is the most studied application of gene therapy. Many genetic alterations are involved in the transformation of a normal cell into a neoplastic one. The two main gene groups involved in cancer development are oncogenes and tumor suppressor genes. While the latter eliminates cancerous cells via apoptosis, the former enhances cell proliferation. Therefore, apoptotic genes and anti-oncogenes are widely used in cancer gene therapy. In addition to oncogenes and tumor suppressor genes, chemotherapy and gene therapy can be combined through suicide gene strategy. A suicide gene encodes for a non-mammalian enzyme; this enzyme is used to convert a non-toxic prodrug into its active cytotoxic metabolite within the cancerous cells. Tumor suppressor genes, anti-oncogenes and suicide genes target cancer cells on the molecular level. On the other hand, cancer is immunogenic in nature; therefore, it can also be targeted on the immunological level. Boosting the immune response against cancerous cells is usually achieved via genes encoding for cytokines. Interleukin-12 gene, for example, is one of the most studied cytokine genes for cancer gene therapy applications. DNA vaccines are also used after conventional treatments to eliminate remnant malignant cells. All these therapeutic strategies and other strategies namely anti-angiogenesis and drug resistant genes are briefly reviewed and highlighted in this article.

Chemosensitization of bladder cancer cell lines by human telomerase reverse transcriptase antisense treatment

PURPOSE

Responses of transitional cell carcinoma of the bladder (TCC) to commonly used chemotherapy agents such as mitomycin C (MMC), cisplatin and gemcitabine are often disappointing. Since human telomerase reverse transcriptase (hTERT) is tumor specifically expressed and contributes to the immortality and malignancy of the majority of tumors, it is regarded as a suitable antitumor target. We investigated whether combinations of hTERT antisense (AS)-oligonucleotides (ODNs) with common chemotherapy (CT) schedules may improve drug mediated antitumor effects.

MATERIALS AND METHODS

Initial screening for enhancement of the inhibitory effects of MMC, cisplatin and gemcitabine on viability by treatment with the 2 hTERT AS-ODNs ASt2206 and ASt2331 was performed in 4 TCC cell lines prior to CT. Apoptosis was assessed by annexin V staining and detection of activated caspase-3 using Western blot analysis. Nonsense (NS)-ODN served as a control in all experiments.

RESULTS

All cell lines responded to the anticancer agents tested. Treatment with AS plus CT resulted in a significantly stronger inhibition of viability than the NS plus CT control in the majority of combinations, indicating an AS specific enhancement effect. For example, ASt2331 plus MMC decreased viability to 17% in contrast to NS plus MMC (58%) in EJ28 cells. All ASt2331 plus CT combinations specifically increased the rate of apoptosis 1.3 to 3.0-fold compared with NS plus CT. Apoptosis induction was associated with caspase 3 activation.

CONCLUSIONS

Enhancement of cytotoxic drug effects on the growth of TCC cells by hTERT AS-ODNs presented herein allows a dose decrease in chemotherapy and confirms the suitability of hTERT as a target in a specific therapy approach.

Cytotoxicity of cisplatin in bladder cancer is significantly enhanced by application of bcl-2 antisense oligonucleotides

BACKGROUND

The aim of our study was to examine the effects of the combined application of cisplatin and bcl-2 antisense oligonucleotide on human bladder cancer cell lines to determine the possible synergistic effects in cytotoxicity and to estimate its potential value for subsequent in vivo trials.

MATERIALS AND METHODS

Human bladder cancer cell lines (UM-UC 3, RT 112, T24/83 and HT 1197) were treated with bcl-2 antisense oligonucleotide, cisplatin, or a combination of both and incubated for 48 h under standard conditions. Cell survival was determined using a Neubauer haemocytometer or standard MTT assay. BCL-2 expression was verified using western blotting.

RESULTS

The combined treatment resulted in significant lower cell survival rates compared to individual treatment. Additionally, there was a decrease in cell survival rate with an increase in cisplatin concentration in combined treatment that was not observed in cisplatin mono treatment.

CONCLUSIONS

For the combined treatment with oligonucleotides and cisplatin a synergistic effect can be strongly suggested. Therefore, further investigations and in vivo trials have to be done to determine the possible benefits for clinical applications.

Survivin antisense oligodeoxynucleotide inhibits growth of gastric cancer cells

AIM: To investigate the effect of transfected survivin antisense oligonucleotide (ASODN) on proliferation and apoptosis of gastric cancer cells.

METHODS: The authors designed ASODNs targeting different regions of survivin mRNA, including surviving ASODN1, ASODN2 and ASODN3. ASODNs were transfected into gastric cancer cell line SGC 7901, cell growth was detected by MTT assay. Cells exposed to the potent oligonucleotide were also examined for apoptosis induction by FCM and fluorescence microscopy. Semiquantitive RT-PCR and Western blot examinations were carried for expression of survivin mRNA and protein.

RESULTS: ASODN3 caused a statistically significant reduction of cell viability to 60.6% (± 2.9%) (P < 0.01), while ASODN1 and ASODN2 had no such changes (P > 0.05). The cell growth was also significantly inhibited by ASODN3, compared with reversal and scrambled sequence. A significant loss of survivin mRNA was presented in ASODN3 treated cells and this was not seen in treatment with sense ODN or scramble ODN. Protein level was significantly decreased 48 h after survivin ASODN trasfected by approximately 2-fold decrease compared with untreated controls. However, ASODN3 did not induce significant apoptosis response until 48 h after transfection (P > 0.05).

CONCLUSION: ASODN3, which targets translation initiation part, can be identified as a most potent antisense compound. Srvivin ASODN3 may provide a novel approach to therapy of gastric cancer.

Expression of Survivin, a Novel Inhibitor of Apoptosis, in Superficial Transitional Cell Carcinoma of the Bladder

PURPOSE

We investigated whether the over expression of survivin, a new antiapoptotic protein, might provide prognostic information in patients with superficial bladder cancer.

MATERIALS AND METHODS

Immunohistochemical staining of paraffin sections using a monoclonal antibody for survivin was performed in 88 cases of superficial bladder cancer using the standard avidin-biotin-peroxidase technique. The relationships between the expression of survivin, clinicopathological characteristics and clinical outcome were analyzed.

RESULTS

Survivin expression was found in tumor cells but not in nonneoplastic bladder tissues. High expressions (greater than 20%) of survivin were observed in 51 cases (58.0%) and low expression in 37 cases. No statistically significant association was observed between survivin expression and tumor grade (p = 0.052) or pathological stage (p = 0.131). When clinical data such as sex, age, tumor number, size or shape were examined in conjunction with survivin status no statistically significant relationship was noted. Patients with a high expression of survivin had worse disease-free survival rates than those with low survivin expression (log rank test p = 0.0004). Multivariate Cox proportional hazards model analysis identified survivin expression as an independent prognostic factor of disease-free survival (p = 0.009, relative risk = 3.17).

CONCLUSIONS

Our findings suggest that high survivin expression may be considered a new unfavorable prognostic factor in superficial bladder cancer.

Recent advances in the development of anticancer agents targeting cell death inhibitors in the Bcl-2 protein family

Hematopoietic malignancies frequently are characterized by defects in apoptosis signaling. This renders the malignant cells resistant to endogenous apoptotic stimuli, as well as exogenous stimuli, such as chemotherapy drugs and radiation. The defective apoptosis seen in human cancers often results from overexpression of antiapoptotic proteins in the Bcl-2 protein family, particularly Bcl-2 and Bcl-X(L). A great deal of effort is currently aimed at developing novel agents to inhibit the expression or function of these proteins. Antisense agents directed against Bcl-2 mRNA are showing considerable promise in clinical trials. In addition, detailed knowledge of the structures of Bcl-2 and Bcl-X(L), coupled with high-throughput and computer-assisted screening of chemical libraries, has led to the identification of a number of short peptides and small organic molecules capable of inhibiting Bcl-2 and Bcl-X(L) function. These newly described agents hold considerable promise for enhancing the chemo- and radiation sensitivities of Bcl-2- and Bcl-X(L)-overexpressing cancers. This review will highlight recent advances in the development and testing of agents targeting cell death inhibitors in the Bcl-2 protein family.

Cyclin E overexpression enhances cytokine-mediated apoptosis in MCF7 breast cancer cells

Cyclin E, the regulatory component of the cyclin E/cyclin-dependent kinase (CDK) complex, is required for proliferation and overexpression of this cyclin is associated with many types of human tumors. To elucidate the mechanism by which cyclin E overexpression promotes tumorigenesis, cyclin E was overexpressed in two breast cancer lines: MCF7 and T47D. Cells overexpressing cyclin E display a marked decrease in the expression of Bcl-2, an antiapoptotic protein, and increased levels of the proapoptotic proteins Bad and Bax. The levels of Bcl-X(L) and Mcl-1 remain unchanged. Since the homeostasis of pro- and antiapoptotic proteins was altered, we asked if cyclin E overexpression modifies responses to cytokines. MCF7 cyclin E overexpressing cells have an enhanced sensitivity to Fas, TRAIL, and TNF-alpha-induced apoptosis. T47D cells overexpressing cyclin E have a significant increase in TNF-alpha and TRAIL-induced apoptosis. In conclusion, our results provide a link between expression of cyclin E, deregulation of Bcl-2, and an altered response to cytokine-mediated apoptosis.

Therapeutic approaches to bladder cancer: identifying targets and mechanisms

Transitional cell carcinoma is the second most common genitourinary malignancy in US and third most common cause of death among genitourinary tumors. Treatment options for bladder cancer include surgery, often combined with chemotherapy, radiation, and/or immunotherapy. The MVAC adjuvant chemotherapy regimen has been most widely used in locally invasive as well as metastatic disease. Only a proportion of patients at risk will respond to therapy. There is thus need to identify good responder patients for adjuvant therapy and to identify new targets to treat a greater range of patients. Based upon patient-specific aberrations in pathways or known markers, both existing and new therapies can be tailored to benefit patients based on the risk of progression and molecular alterations specific to a patient's tumor. Targeted therapy, therefore, is defined as therapy that targets mechanism and risk. Utilizing the available knowledge of the molecular biology of cell-cycle regulation, signal transduction, apoptosis, and angiogenesis in bladder cancer, we review the potential therapeutic targets for rational drug development. Finally, using bladder cancer as a model for translational research, requirements for a desired clinical trial are presented.

Potentiation of dexamethasone-, paclitaxel-, and Ad-p53-induced apoptosis by Bcl-2 antisense oligodeoxynucleotides in drug-resistant multiple myeloma cells

Overexpression of Bcl-2 in myeloma cells results in resistance to drugs such as dexamethasone (DEX), adenovirus-mediated delivery of p53 (Ad-p53), and paclitaxel (TAX), which work through the intrinsic apoptotic pathway. Bcl-2 antisense oligodeoxynucleotides (Bcl-2-ASO) have been shown to induce apoptosis in cancer cells, as a single agent or, better, in combination with chemotherapy. We hypothesized that down-regulation of Bcl-2 by Bcl-2-ASO will sensitize drug-resistant myeloma cells to undergo apoptosis. In this paper we report a detailed time/dose study of the effect of Bcl-2-ASO on myeloma cells with varying levels of Bcl-2. Treatment of myeloma cells expressing relatively low levels of Bcl-2 with Bcl-2-ASO resulted in a substantial apoptosis concomitant with a substantial depletion of Bcl-2 protein. Maximal apoptosis was observed at 5 to 10 microg/mL Bcl-2-ASO, following 4 days of treatment. Down-regulation of Bcl-2 and apoptosis were time and dose dependent and were sequence specific. In these cell lines, apoptosis was accompanied by activation of caspase-9 and caspase-3 and by release of cytochrome c to the cytosol. In contrast, high Bcl-2-expressing myeloma cells were practically resistant to Bcl-2-ASO. Most important, however, pretreatment of myeloma cells expressing high levels of Bcl-2 with Bcl-2-ASO increased the extent of DEX-, TAX-, and Ad-p53-induced apoptosis from 10%-20% to 70%-90%. Increased apoptosis was accompanied by additional decrease in Bcl-2 protein. Similar results for down-regulation of Bcl-2 and apoptosis were obtained with freshly isolated myeloma cells. These data support development of clinical trials with combinations of Bcl-2-ASO and DEX, TAX, or Ad-p53 in the treatment of refractory myeloma patients.

Antisense oligonucleotide therapy for urologic tumors

Modulation of gene expression using antisense oligonucleotides has advanced from the laboratory to the clinic. Numerous companies can, at least partially, attribute their success to the development of antisense techniques, and one antisense drug is currently on the market. Antisense compounds have been used in clinical trials that included patients with urologic tumors, mostly directed at proliferation- or apoptosis-related targets. Furthermore, therapeutic inhibition of many new identified genes is being investigated in preclinical tests. This review provides a contemporary overview of current preclinical and clinical antisense oligonucleotide concepts for the treatment of urologic tumors.

Localized and locally advanced bladder cancer

Localized and locally advanced bladder cancer represents a heterogeneous spectrum of diseases with different biologic and clinical behavior. It varies with respect to invasive potential, propensity for metastases, and sensitivity to chemotherapy. Although several significant surgical advances have been made over the past 20 years in the treatment of muscle-invasive bladder cancer, resulting in decreases in perioperative morbidity and mortality and improvement of quality of life in patients with continent urinary diversions, the natural history of the disease has remained unaltered. Advances in chemotherapy for metastatic disease have prompted trials of systemic therapy in patients with early stage, high-risk disease administered before or after local therapy consisting of cystectomy or radiotherapy. The data available from nonrandomized and randomized trials have not definitively established the exact role of neoadjuvant chemotherapy and its impact on survival. Even if neoadjuvant chemotherapy does not improve survival, preliminary data suggest that bladder preservation may be possible in selected patients and that such combined therapy will hopefully lead to better patient management. The trials of postoperative chemotherapy provide insufficient evidence to support the routine use of adjuvant chemotherapy in clinical practice as a result of small sample size, confusing analyses, and the reporting of questionable conclusions. New large-scale, multicenter trials are imperative to provide convincing results. A better understanding of the microbiology of bladder cancer will influence the search for new therapeutic modalities. Molecular-targeted small-molecule therapy and monoclonal antibodies have begun to dominate contemporary studies.