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

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.

Bcl-xL: A Focus on Melanoma Pathobiology

Apoptosis is the main mechanism by which multicellular organisms eliminate damaged or unwanted cells. To regulate this process, a balance between pro-survival and pro-apoptotic proteins is necessary in order to avoid impaired apoptosis, which is the cause of several pathologies, including cancer. Among the anti-apoptotic proteins, Bcl-xL exhibits a high conformational flexibility, whose regulation is strictly controlled by alternative splicing and post-transcriptional regulation mediated by transcription factors or microRNAs. It shows relevant functions in different forms of cancer, including melanoma. In melanoma, Bcl-xL contributes to both canonical roles, such as pro-survival, protection from apoptosis and induction of drug resistance, and non-canonical functions, including promotion of cell migration and invasion, and angiogenesis. Growing evidence indicates that Bcl-xL inhibition can be helpful for cancer patients, but at present, effective and safe therapies targeting Bcl-xL are lacking due to toxicity to platelets. In this review, we summarized findings describing the mechanisms of Bcl-xL regulation, and the role that Bcl-xL plays in melanoma pathobiology and response to therapy. From these findings, it emerged that even if Bcl-xL plays a crucial role in melanoma pathobiology, we need further studies aimed at evaluating the involvement of Bcl-xL and other members of the Bcl-2 family in the progression of melanoma and at identifying new non-toxic Bcl-xL inhibitors.

Suberoylanilide Hydroxamic Acid Can Re-sensitize a Cisplatin-Resistant Human Bladder Cancer

Cisplatin chemotherapy is the standard treatment for metastatic urothelial carcinoma. Although there are second-line chemotherapeutic agents approved by the U.S. Food and Drug Administration (FDA) such as those targeting programmed death-ligand 1 (PD-L1), more effective pharmacotherapy is required for cisplatin-resistant bladder cancer due to its limited overall survival and progression-free survival. The synergistic anti-cancer effect of cisplatin and suberoylanilide hydroxamic acid (SAHA) in cisplatin-resistant bladder cancer cells (T24R2) was examined. Tumor cell proliferation and cell cycle was examined using the cell counting kit (CCK)-8 assays and flow cytometry, respectively. Synergism was examined using the combination index (CI). CCK-8 assay and CI test were used to observe the strong synergistic anti-cancer effect between SAHA and cisplatin. Activation of caspase mediated apoptosis, down-regulated expression of the anti-apoptotic B-cell lymphoma-2 (Bcl-2) and up-regulated expression of pro-apoptotic Bcl-2-associated death promoter (BAD) were observed in Western blot. SAHA synergistically could partially re-sensitize cisplatin-resistant bladder cancer cells (T24R2) through the cell cycle arrest and induction of apoptosis pathway. SAHA-based treatment could be a potential treatment regimen in patients with cisplatin resistant bladder cancer.

Antisense- and siRNA-mediated inhibition of the anti-apoptotic gene Bcl-xL for chemosensitization of bladder cancer cells

Bcl-xL is an apoptosis inhibitor that is upregulated in bladder cancer (BCa) and provides an attractive target for molecular therapies. Treatment with specific antisense oligodeoxynucleotides (AS‑ODNs) or small interfering RNAs (siRNAs) were able to sensitize BCa cells to conventional chemotherapeutics. Ten new Bcl‑xL‑targeting AS‑ODNs were systematically designed by using predicting software. AS‑BX2034 and AS‑BX2100 as well as the previously optimized siRNA construct si‑BX713 were selected for further detailed in vitro analysis in the BCa cell lines UM‑UC‑3 and EJ28. Bcl‑xL mRNA and protein expression levels, cell viability and apoptosis were examined 72 h after transfection. A single treatment with AS‑BX2034 or AS‑BX2100 caused only a low inhibition of the Bcl‑xL mRNA expression with the highest reduction of ≤20% in UM‑UC‑3 cells. In contrast, a single treatment with si‑BX713 strongly decreased Bcl‑xL mRNA expression level by ≤69% in UM‑UC‑3 cells and by ≤86% in EJ28 cells. Both gene expression inhibitor types induced a low to moderate reduction of viability. Depending on the cell line, a combined treatment with AS‑BX2100 or si‑BX713 and cisplatin (CDDP) caused an additional inhibition of cell viability by ~33 and 38%, respectively, compared to the respective control construct combined with CDDP. In comparison to the respective control treatment, combinations of AS‑BX2100 and CDDP led to a stronger induction of apoptosis by 57% in UM‑UC‑3 cells and 44% in EJ28 cells, whereas the combination of si‑BX713 and CDDP enhanced apoptosis by 38 and 118% in UM‑UC‑3 and EJ28 cells, respectively. Our comparative studies showed a stronger knockdown of Bcl‑xL by the siRNA construct compared to AS‑ODN treatment in both BCa cell lines. In combinatory treatments, the Bcl‑xL-directed siRNA markedly enhanced the anti-proliferative and apoptotic effects of CDDP and therefore, may serve as suitable tool for chemosensitization of BCa cells.

Novel molecular targets for urothelial carcinoma

INTRODUCTION

Urothelial cancer (UC) remains a significant public health problem, with no new second-line agents FDA-approved in the US. Next-generation sequencing technologies are starting to generate a molecular landscape of UC thus revealing novel molecular targets.

AREAS COVERED

In this review, the authors provide a detailed review of novel molecular targets in UC based on published genomic analyses of urothelial tumors. We provide an overview of each molecular target with a brief discussion of therapeutic strategies and clinical trials targeting each pathway.

EXPERT OPINION

UC continues to be a lethal disease with no FDA-approved effective second-line therapies. Platinum resistance continues to be a daunting clinical problem. Next-generation sequencing methods have led to the elucidation of numerous molecular targets in UC, including PI3K, to the elucidation of numerous molecular targets in UC, including PI3K, ERBB2 and FGFR3, among many others. These molecular perturbations can be exploited therapeutically with targeted therapies in patient populations enriched for these molecular alterations, thus paving the way for precision medicine in UC management.

The cytotoxic activities of 7-isopentenyloxycoumarin on 5637 cells via induction of apoptosis and cell cycle arrest in G2/M stage

BACKGROUND

Bladder cancer is the second common malignancy of genitourinary tract, and transitional cell carcinomas (TCCs) account for 90% of all bladder cancers. Due to acquired resistance of TCC cells to a wide range of chemotherapeutic agents, there is always a need for search on new compounds for treatment of these cancers. Coumarins represent a group of natural compounds, which some of them have exerted valuable anti-tumor activities. The current study was designed to evaluate anti-tumor properties and mechanism of action of 7-isopentenyloxycoumarin, a prenyloxycoumarin, on 5637 cells (a TCC cell line).

RESULTS

MTT results revealed that the cytotoxic effects of 7-isopentenyloxycoumarin on 5637 cancerous cells were more prominent in comparison to HDF-1 normal cells. This coumarin increased the amount of chromatin condensation and DNA damage in 5637 cells by 58 and 33%, respectively. The results also indicated that it can induce apoptosis most probably via activation of caspase-3 in these cells. Moreover, propidium iodide staining revealed that 7-isopentenyloxycoumarin induced cell cycle arrest at G2/M stage, after 24 h of treatment.

CONCLUSION

Our results indicated that 7-isopentenyloxycoumarin had selective toxic effects on this bladder cancer cell line and promoted its effects by apoptosis induction and cell cycle arrest. This coumarin can be considered for further studies to reveal its exact mechanism of action and also its anti-cancer effects in vivo.

Molecular mechanisms of cisplatin resistance in bladder cancer

Metastatic disease is the most common mechanism of death in patients with advanced bladder cancer. As for most solid tumors, chemotherapy remains the only realistic option for palliating or curing metastatic disease. However, bladder cancer is characterized by chemoresistance. Only modest response rates are obtained using multiagent regimens including cisplatin. These low response rates and the toxicity of these regimens limit their use to patients at highest risk. Here, we review the molecular mechanisms of cisplatin resistance. These include methods to reduce cisplatin bioavailability within a cell, and defects in the machinery that produces cell death following cisplatin-induced DNA damage. While overcoming these mechanisms is a potential therapeutic approach that can increase response rates, in the short term this knowledge could be used to predict response in individual tumors.

Effects of novel all-trans retinoic acid retinamide derivatives on the proliferation and apoptosis of human lung adenocarcinoma cell line A549 cells

The aim of the present study was to synthesize a series of retinamide derivatives using all-trans retinoic acid (ATRA) as raw material and observe their effects on the differentiation and apoptosis of human lung adenocarcinoma A549 cells. Four new synthesized ATRA retinamide derivatives were structurally confirmed by spectral analysis, including (1)H-NMR, (13)C-NMR, and MS. The results showed that the new ATRA retinamide derivatives significantly decreased the carcinoembryonic antigen secretion of A549 cells, significantly decreased the proliferation of A549 cells in a dose- and time-dependent manner, and promoted the apoptosis of A549 cells compared with ATRA. The Western blot assay indicated that the expression of Bcl-2 was decreased more in A549 cells treated with N-(3-trifluoromethylphenyl) retinamide than that in A549 cells treated with ATRA. The results also showed that the effects of N-(3-trifluoromethyl-phenyl) retinamide on differentiation and apoptosis were the strongest among the newly synthesized ATRA retinamide derivatives. Our results suggested that the effects of novel ATRA retinamide derivatives on increasing the differentiation, decreasing the proliferation, and promoting the apoptosis of A549 cells were greater than those of ATRA. The apoptosis of A549 cells induced by N-(3-trifluoromethylphenyl) retinamide may be related to downregulating the expression of Bcl-2.

The histone deacetylase inhibitor trichostatin A synergistically resensitizes a cisplatin resistant human bladder cancer cell line

PURPOSE

Cisplatin is the mainstay of treatment for advanced bladder cancer. However, intrinsic or acquired resistance to cisplatin is common, which severely limits its therapeutic potential. We determined the synergistic antitumor effect of cisplatin and the histone deacetylase inhibitor trichostatin A in cisplatin resistant human bladder cancer cells.

MATERIALS AND METHODS

The cisplatin resistant human bladder cancer cell line T24R2 was exposed to cisplatin and/or trichostatin A. Tumor cell proliferation was examined by cell counting kit assay. Synergism between 2 drugs was examined by the combination index. Changes in cell cycle and apoptosis were determined by flow cytometry. We analyzed the expression of caspase-3, 8 and 9, poly(adenosine diphosphate-ribose) polymerase, p21WAF1/CIP1, cyclin A, B1 and D1, Cdc2c, p-Cdc2c, Cdc25c, p-Cdc25c, cytochrome c, p-Akt, t-Akt, Bcl-2, Bax, Bad, vascular endothelial growth factor and fetal liver kinase-1 by Western blot and colorimetric assay.

RESULTS

Based on the combination index and isobole analysis of the Cell Counting Kit-8 assay we observed a strong synergistic antitumor effect between cisplatin and trichostatin A, allowing a 3.5 and 4.9-fold dose reduction in cisplatin and trichostatin A, respectively, while achieving an estimated 90% kill of T24R2 cells. The underlying mechanism could be synergistic cell cycle arrest, induction of caspase mediated apoptosis or up-regulated expression of pro-apoptotic Bad and Bax.

CONCLUSIONS

Results indicate that trichostatin A may synergistically enhance the antitumor effect of cisplatin and resensitize cisplatin resistant bladder cancer cells. These findings suggest the potential use of histone deacetylase inhibitor as a combination agent to enhance the antitumor effect of cisplatin in patients with advanced bladder cancer.

Effect of mitomycin C on concentrations of vascular endothelial growth factor and its receptors in bladder cancer cells and in bladders of rats intravesically instilled with mitomycin C

OBJECTIVES

• To examine, using in vitro and in vivo models, the largely unexamined effect of mitomycin C (MMC), an effective intravesical treatment for superficial bladder cancer and carcinoma in situ, on expression of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor-2 (VEGFR-2), which mediates many of the angiogenic properties of VEGF. • To measure, as a positive control, concentrations of the inhibitor of apoptosis, survivin, as an assessment of MMC effectiveness. • To measure MMC-induced changes in proliferation in the presence and absence of VEGF-A small interfering RNA (siRNA).

MATERIALS AND METHODS

• After treatment with increasing MMC concentrations (5-200 µg/mL), we measured proliferation, as well as VEGF, survivin, VEGF receptor-1 (VEGFR-1) and VEGFR-2 concentrations in RT-4 and T-24 bladder cancer cells. • The effect of pre-treatment of VEGF siRNA and survivin siRNA on MMC-induced decreases in proliferation was measured. • Urinary VEGF concentrations and bladder and kidney concentrations of VEGF-A, VEGFR-1, VEGFR-2 and interleukin-6 (IL-6) mRNA were measured in rats intravesically instilled with saline or MMC (200 µg/mL).

RESULTS

• Although MMC treatment inhibited cell proliferation and decreased survivin mRNA expression in T-24 and RT4 cells, MMC (12-50 µg/mL) increased VEGF-A mRNA and VEGFR-2 mRNA and protein expression. • Pre-treatment with VEGF-A siRNA or survivin siRNA before MMC treatment reduced proliferation more than MMC alone. • MMC-induced reductions in proliferation were reduced additively by pre-treatment with survivin siRNA, but were potentiated by pre-treatment with VEGF-A siRNA. • VEGFR-2 mRNA and protein concentrations and urinary VEGF concentrations were increased in bladders of rats instilled with MMC.

CONCLUSIONS

• Intravesically instilled MMC increases urinary VEGF and bladder VEGFR-2 protein and mRNA in rats. • MMC increases VEGF mRNA and VEGFR-2 protein and mRNA concentrations in bladder cancer cells. Therefore, we speculate that MMC could increase the angiogenic potential of both cancer and normal cells. • In cancer cells this effect is largest at lower MMC concentrations. • Combining MMC with agents that reduce EGF concentrations could be of value in treatment of transitional cell carcinoma of the bladder (TCC).

New therapies for non-muscle-invasive bladder cancer

The treatment of non-muscle-invasive bladder cancer (NMIBC) remains a challenge owing to its increased tendency to recur and the possibility of progression to potentially dangerous muscle-invasive disease. Treatment outcomes by current therapeutic modalities are still not optimal. In recent years, there have been a number of substantive advances in the therapeutic options for the management of NMIBC. New chemotherapeutic drugs have been introduced, along with efforts made to improve the efficacy of existing agents and enhance delivery of agents to the bladder. There is also a growing trend toward combination of agents and multimodal therapy. Also of considerable interest are the investigation of newer approaches such as gene therapy, chemoenhancement and newer forms of immunotherapy. Here, we review the recent pre-clinical and clinical developments in the treatment of NMIBC, described in the broad categories of immunotherapy, chemotherapeutic agents, improved or device-assisted agent delivery and gene therapy.

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.

In vivo evaluation of intravesical paclitaxel and combined bcl-xL antisense oligodeoxynucleotide treatment for orthotopic urothelial carcinoma

PURPOSE

To evaluate intravesical paclitaxel monotherapy and combined treatment with antiapoptotic bcl-xL antisense oligodeoxynucleotides (AS-ODNs) on urothelial carcinoma (UC).

METHODS

Forty-eight FoxN(rnu) athymic nude rats with orthotopic human bladder UC were randomized to four treatment groups [1, paclitaxel; 2, paclitaxel/bcl-xL AS-ODNs; 3, bcl-xL AS-ODNs (control); 4, medium (control)]. Three consecutive instillations were applied and weekly endoscopic tumor size measurements were performed.

RESULTS

Significant tumor size reduction was achieved in groups 1 and 2 (each P < 0.0001), whereas continuous UC growth was observed in control animals (groups 3 and 4; P < 0.0001 and P < 0.0020). Complete tumor eradication was achieved in four treated animals (groups 1 and 2). No significant difference in chemoresection effects was found between groups 1 and 2 (P = 0.2251).

CONCLUSIONS

We present an in vivo evaluation of intravesical treatment with paclitaxel and combined bcl-xL AS-ODNs. Despite efficient tumor size reduction, no gain was observed when adding bcl-xL AS-ODNs in this experimental setting.

Systemic therapy for unresectable and metastatic transitional cell carcinoma of the urothelium: first-line and beyond

PURPOSE OF REVIEW

The review aims to provide an overview of recent advances and future research direction in the management of patients with advanced transitional cell carcinoma.

RECENT FINDINGS

Early data of the randomized phase III study comparing paclitaxel, cisplatin, and gemcitabine with gemcitabine plus cisplatin for advanced urothelial cancer detected no survival difference. A phase II study investigated the safety and efficacy of trastuzumab, carboplatin, gemcitabine, and paclitaxel in human epidermal growth factor receptor-2/neu-positive advanced urothelial carcinoma and reported promising results. Renal-sparing regimens are under active development. A nonrandomized comparison of the 3-week with the 4-week schedule for gemcitabine and cisplatin showed that the 3-week schedule had less hematological toxicity and better dose intensity. Potential molecular markers such as excision repair cross-complementation group 1, emmprin, and survivin for survival and/or platinum resistance in patients with transitional cell carcinoma showed promise.

SUMMARY

Recent data do not support change in the current standard of care for advanced transitional cell carcinoma. Clinical testing of emerging anticancer therapies using new agents, new combinations, and new approaches is under active investigation. Rational combination and new strategy in clinical trial design are critical for new drug development for transitional cell carcinoma.

Research progress in anti-apoptosis gene Bcl-xL

Apoptosis is a physiological process that an organism selectively eliminates cells that are no longer needed, or have been damaged, or are dangerous. Bcl-xL, an important member of the Bcl-2 family that plays indispensable roles in regulating cell survival and apoptosis, is frequently over-expressed in various kinds of human cancers. The inhibition of this molecule is associated with decreased tumorigenesis and resistance to conventional chemotherapy. This article briefly reviews some progresses in the study of Bcl-xL in the past few years.