Antisense oligonucleotide therapy in the management of bladder cancer

HMGN5 promotes IL-6-induced epithelial-mesenchymal transition of bladder cancer by interacting with Hsp27

Bladder cancer (BC) is one of the most common cancers worldwide, with a high rate of recurrence and poor outcomes. High-mobility group nucleosome-binding domain 5 (HMGN5) is overexpressed in many cancers and could cause carcinogenesis in BC. By protein-protein-interaction (PPI) analysis, we found that heat shock protein 27 (Hsp27), also a crucial functional factor in BC carcinogenesis, is significantly related to HMGN5. Hsp27 is required for IL-6-mediated EMT via STAT3/Twist signaling in prostate cancer. Here, we hypothesize that HMGN5 may interact with Hsp27 to affect IL-6-induced EMT and invasion in BC via STAT3 signaling. In the present study, we found that HMGN5 and Hsp27 are highly expressed in BC tissues and positively correlated with each other. HMGN5 interacts with Hsp27 in vitro, to modulate the cell invasion and EMT in BC. Moreover, HMGN5 could modulate IL-6-Hsp27-induced EMT and invasion in BC cells by regulating STAT3 phosphorylation and STAT3 targeting of the Twist promoter. HMGN5 interacts with Hsp27 to promote tumor growth in a human BC xenograft model in nude mice. In summary, HMGN5 interacts with Hsp27 to promote IL-6-induced EMT, therefore promoting invasion in BC and contributing to the progression of BC.

Investigation of Sub-100 nm Gold Nanoparticles for Laser-Induced Thermotherapy of Cancer

Specialized gold nanostructures are of interest for the development of alternative treatment methods in medicine. Photothermal therapy combined with gene therapy that supports hyperthermia is proposed as a novel multimodal treatment method for prostate cancer. In this work, photothermal therapy using small (<100 nm) gold nanoparticles and near-infrared (NIR) laser irradiation combined with gene therapy targeting heat shock protein (HSP) 27 was investigated. A series of nanoparticles: nanoshells, nanorods, core-corona nanoparticles and hollow nanoshells, were synthesized and examined to compare their properties and suitability as photothermal agents. In vitro cellular uptake studies of the nanoparticles into prostate cancer cell lines were performed using light scattering microscopy to provide three-dimensional (3D) imaging. Small gold nanoshells (40 nm) displayed the greatest cellular uptake of the nanoparticles studied and were used in photothermal studies. Photothermal treatment of the cancer cell lines with laser irradiation at 800 nm at 4 W on a spot size of 4 mm (FWHM) for 6 or 10 min resulted in an increase in temperature of ~12 °C and decrease in cell viability of up to 70%. However, in vitro studies combining photothermal therapy with gene therapy targeting HSP27 did not result in additional sensitization of the prostate cancer cells to hyperthermia.

RNAi-based therapeutics targeting survivin and PLK1 for treatment of bladder cancer

Harnessing RNA interference (RNAi) to silence aberrant gene expression is an emerging approach in cancer therapy. Selective inhibition of an overexpressed gene via RNAi requires a highly efficacious, target-specific short interfering RNA (siRNA) and a safe and efficient delivery system. We have developed siRNA constructs (UsiRNA) that contain unlocked nucleobase analogs (UNA) targeting survivin and polo-like kinase-1 (PLK1) genes. UsiRNAs were encapsulated into dialkylated amino acid-based liposomes (DiLA(2)) containing a nor-arginine head group, cholesteryl hemisuccinate (CHEMS), cholesterol and 1, 2-dimyristoyl-phosphatidylethanolamine-polyethyleneglycol 2000 (DMPE-PEG2000). In an orthotopic bladder cancer mouse model, intravesical treatment with survivin or PLK1 UsiRNA in DiLA(2) liposomes at 1.0 and 0.5 mg/kg resulted in 90% and 70% inhibition of survivin or PLK1 mRNA, respectively. This correlated with a dose-dependent decrease in tumor volumes which was sustained over a 3-week period. Silencing of survivin and PLK1 mRNA was confirmed to be RNA-induced silencing complex mediated as specific cleavage products were detected in bladder tumors over the duration of the study. This report suggests that intravesical instillation of survivin or PLK1 UsiRNA can serve as a potential therapeutic modality for treatment of bladder cancer.

Chapter 2: Clusterin (CLU): From one gene and two transcripts to many proteins

Clusterin (CLU) has kept many researchers engaged for a long time since its first discovery and characterization in the attempt to unravel its biological role in mammals. Although there is a general consensus on the fact that CLU is supposed to play important roles in nearly all fundamental biological phenomena and in many human diseases including cancer, after about 10 years of work CLU has been defined as an "enigmatic" protein. This sense of frustration among the researchers is originated by the fact that, despite considerable scientific production concerning CLU, there is still a lack of basic information about the complex regulation of its expression. The CLU gene is a single 9-exon gene expressed at very different levels in almost all major tissues in mammals. The gene produces at least three protein forms with different subcellular localization and diverse biological functions. The molecular mechanism of production of these protein forms remains unclear. The best known is the glycosylated mature form of CLU (sCLU), secreted with very big quantitative differences at different body sites. Hormones and growth factors are the most important regulators of CLU gene expression. Before 2006, it was believed that a unique transcript of about 1.9 kb was originated by transcription of the CLU gene. Now we know that alternative transcriptional initiation, possibly driven by two distinct promoters, may produce at least two distinct CLU mRNA isoforms differing in their unique first exon, named Isoform 1 and Isoform 2. A third transcript, named Isoform 11036, has been recently found as one of the most probable mRNA variants. Approaches like cloning, expression, and functional characterization of the different CLU protein products have generated a critical mass of information teaching us an important lesson about CLU gene expression regulation. Nevertheless, further studies are necessary to better understand the tissue-specific regulation of CLU expression and to identify the specific signals triggering the expression of different/alternative transcript isoforms and protein forms in different cell types at appropriate time.

Transcriptome profiling of a TGF-beta-induced epithelial-to-mesenchymal transition reveals extracellular clusterin as a target for therapeutic antibodies

Transforming growth factor (TGF)-beta plays a dual role in tumorigenesis, switching from acting as a growth inhibitory tumor suppressor early in the process, to a tumor promoter in late-stage disease. Since TGF-beta's prometastatic role may be linked to its ability to induce tumor cell epithelial-to-mesenchymal transition (EMT), we explored TGF-beta's EMT-promoting pathways by analysing the transcriptome changes occurring in BRI-JM01 mammary tumor epithelial cells undergoing a TGF-beta-induced EMT. We found the clusterin gene to be the most highly upregulated throughout most of the TGF-beta time course, and showed that this results in an increase of the secreted form of clusterin. By monitoring several hallmark features of EMT, we demonstrated that antibodies targeting secreted clusterin inhibit the TGF-beta-induced EMT of BRI-JM01 cells, as well as the invasive phenotype of several other breast and prostate tumor cell lines (4T1, NMuMG, MDA-MB231LM2 and PC3), without affecting the proliferation of these cells. These results indicate that secreted clusterin is a functionally important EMT mediator that lies downstream within TGF-beta's EMT-promoting transcriptional cascade, but not within its growth-inhibitory pathways. To further investigate the role played by secreted clusterin in tumor metastasis, we assessed the effect of several anti-clusterin monoclonal antibodies in vivo using a 4T1 syngeneic mouse breast cancer model and found that these antibodies significantly reduce lung metastasis. Taken together, our results reveal a role for secreted clusterin as an important extracellular promoter of EMT, and suggest that antibodies targeting clusterin may inhibit tumor metastasis without reducing the beneficial growth inhibitory effects of TGF-beta.

FUT7 antisense sequence inhibits the expression of FUT7/sLeX and adhesion between embryonic and uterine cells

Implantation is a complex developmental event that is initiated by recognition and adhesion of the embryo to the endometrial epithelium. sLeX is an oligosaccharide antigen acting as the ligand of L-selectin, and is stage-specifically expressed in the endometrial epithelium. The adhesion system mediated by L-selectin and sLeX oligosaccharide plays an important role in this process. FUT7 is a key enzyme for sLeX synthesis, and the regulation of sLeX through FUT7 may influence maternal-fetal recognition. In this study, we observed the effect of FUT7 antisense oligodeoxynucleotide on the expression of FUT7 and sLeX, as well as adhesion in an in vitro implantation model consisting of the human uterine epithelial cell line RL95-2 and the human embryonic cell line JAR. Results showed that the expression of FUT7 was significantly decreased, compared with controls, after FUT7 antisense oligodeoxynucleotide transfection into RL95-2 cells, as determined by RT-PCR, Western blotting, and indirect immunofluorescence. Synthesis of sLeX was also decreased, consistent with the FUT7 decrease, as shown by indirect immunofluorescence. The adhesion of embryonic cells to uterine epithelial cells was significantly reduced (P < 0.01) compared with the control. These data indicate that the use of a FUT7 antisense oligodeoxynucleotide can cause a significant reduction of both FUT7 and sLeX antigen, and thereby inhibit the adhesion of embryo cells to endometrium. This approach may provide a new way to regulate reproduction.

Telomerase targeted oligonucleotide thio-phosphoramidates in T24-luc bladder cancer cells

Bladder carcinoma is the second most common genitourinary malignancy. Treatment options for bladder cancer include surgery, combined with chemotherapy, radiation, and/or immunotherapy. The adjuvant chemotherapy and immunotherapy regimen have been widely used in locally invasive as well as metastatic disease. The evaluation of new active agents with improved tolerability has been the focus of investigations over the past decade with minimal overall improvements in outcomes. Telomerase activity has been found in approximately 85-90% of all human tumors, but not in the majority of adjacent normal tissues. This suggests that telomerase may be an attractive target for the development of novel anticancer therapeutic agents. GRN163L is a lipid conjugated oligonucleotide N3' --> P5' thio-phosphoramidate, and is a potent telomerase RNA (hTR) template antagonist. In the present study, we show that the telomerase activity of T24-luc bladder cancer cells is inhibited by 1 microM GRN163L within 24 h of incubation. After two weeks of exposure to GRN163L, T24-luc cells became "clustered" whereas non-cancerous normal human uroepithelial cells were not morphologically affected. Moreover, in vitro GRN163L treated T24-luc bladder cancer cells entered G(0)/G(1) arrest following 2 weeks of continuous exposure and stopped dividing. Mismatch control compound had no effect on normal bladder epithelial cells or T24-luc cells. Additionally, a new generation of thio-phosphoramidate oligonucleotides were designed and tested in T24-luc cells and compared with GRN163L. The obtained results warrant further in vivo evaluation of GRN163L as a potential treatment for bladder cancer.

Clusterin antisense complexed with chitosan for controlled intratumoral delivery

The purpose of this work was to characterize an injectable, intratumoral, controlled release delivery system for clusterin antisense oligonucleotide (clusterin ASO) based on clusterin ASO complexed with chitosan microparticles (CC complexes) and blended with a biodegradable polymeric paste (CC in paste). The effect of clusterin ASO/chitosan ratio on the physicochemical properties of CC complexes and the influence of chitosan and polymeric paste on the in vitro release and stability of clusterin ASO were investigated. Chitosan had an intrinsic pK(a) of 6.2. Chitosan particles incubated at different pHs swelled to approximately 600% of their dry weight and had a mean diameter of approximately 200microm. As the amount of chitosan in CC complexes was increased or as the pH was decreased, zeta potentials became increasingly less negatively charged and the amount of clusterin ASO complexed with chitosan increased. Clusterin ASO released into PBS or plasma in vitro from polymeric paste and CC in paste in a similar manner with a burst phase of release followed by a slow sustained release. The ratio of clusterin ASO to chitosan and incorporation into polymeric paste influenced the rate and extent of clusterin ASO release. Inclusion of clusterin ASO with or without chitosan in polymeric paste inhibited the in vitro degradation of clusterin ASO in plasma. Treatment of PC-3 cells in vitro with clusterin ASO alone or clusterin ASO released from the various formulations resulted in 52-62% inhibition of the expression of clusterin protein. Degradation studies showed that approximately 40% of the full-length clusterin ASO remained from both clusterin ASO alone and CC complex samples when incubated in 50% plasma in vitro for 4 days. In conclusion, the amount of clusterin ASO loaded into microparticulate chitosan was dependent on the amount of chitosan present and the pH of the environment and clusterin ASO released from the various formulations in a controlled manner and in a bioactive form.

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.