Therapeutic efficacy of adenoviral-mediated p53 gene transfer is synergistically enhanced by combined use of antisense oligodeoxynucleotide targeting clusterin gene in a human bladder cancer model

Semaphorin 3F induces colorectal cancer cell chemosensitivity by promoting P27 nuclear export

Colorectal adenocarcinoma (CRC) is the third most common malignancy worldwide. Metastatic CRC has a poor prognosis because of chemotherapy resistance. Our previous study demonstrated that semaphorin 3F (SEMA3F) signaling may contribute to reversing chemotherapy resistance in CRC cells by reducing E-cadherin and integrin αvβ3 expression levels. Another study showed that upregulation of p27 significantly increase the expression of E-cadherin and integrin. This study aimed to evaluate the effect of SEMA3F on P27 and whether it can reverse resistance in CRC cells. We compared the chemosensitivity of human colorectal cancer cell lines with different SEMA3F expression levels to 5-Fu through cell experiment and animal experiment. Then the interaction between SEMA3F and p27 and its possible mechanism were explored by Western Blot, immunofluorescence and immunocoprecipitation. We also compared the disease-free survival of 118 CRC patients with high or low expression of SEMA3F.The results showed that overexpresstion of SEMA3F enhanced the chemotherapy sensitivity and apoptosis of CRC cells in vitro and in vivo. Among 118 postoperative CRC specimens, the disease-free survival of patients with positive SEMA3F expression was significantly longer than that with negative SEMA3F expression after adjuvant treatment. Upregulation of SEMA3F in multicellular spheroid culture (MSC) could increase p27 phosphorylation at serine 10 (Ser10), subsequently promote the cytosolic translocation of P27. Overall, our results reveal a novel molecular mechanism: SEMA3F mediates the degradation of p27 and regulates its subcellular localization to enhance chemosensitivity to 5-Fu in CRC cells, rather than inhibits p27 expression.

Enhanced Sensitivity to NVP-BEZ235 by Inhibition of p62/SQSTM1 in Human Bladder Cancer KoTCC-1 Cells Both In Vitro and In Vivo

BACKGROUND/AIM

The prognosis of patients with invasive bladder cancer remains poor. The objective of this study was to evaluate the efficacy of NVP-BEZ235 (NVP), a dual PI3K/mTOR inhibitor, combined with the inactivation of p62/SQSTM1 (p62) in a human bladder cancer KoTCC-1 model.

MATERIALS AND METHODS

An expression plasmid with short hairpin RNA targeted against p62 was transfected into KoTCC-1 cells (KoTCC-1/sh-p62). The antitumor effects of NVP on KoTCC-1/sh-p62 were investigated in comparison with those on KoTCC-1 transfected with a control plasmid alone (KoTCC-1/C).

RESULTS

KoTCC-1/sh-p62 showed significantly higher sensitivity to NVP than KoTCC-1/C. Treatment of both cell lines with NVP markedly inactivated the PI3K/Akt/mTOR signaling pathway. However, NVP treatment stimulated the autophagic pathway in KoTCC-1/C, but not in KoTCC-1/sh-p62. Furthermore, compared with KoTCC-1/C, NVP treatment induced apoptosis of KoTCC-1/sh-p62 cells, which was accompanied by significant downregulation of c-IAP-1 and XIAP as well as upregulation of Bax. Moreover, the in vivo growth of KoTCC-1/sh-p62 tumors was significantly suppressed by treatment with NVP compared to KoTCC-1/C tumors.

CONCLUSION

Inhibition of p62 expression combined with NVP may represent an effective therapeutic approach for patients with invasive bladder cancer.

Clusterin inhibition mediates sensitivity to chemotherapy and radiotherapy in human cancer

Since its discovery in 1983, the protein clusterin (CLU) has been isolated from almost all human tissues and fluids and linked to the development of different physiopathological processes, including carcinogenesis and tumor progression. During the last few years, several studies have shown the cytoprotective role of secretory CLU in tumor cells, inhibiting their apoptosis and enhancing their resistance to conventional treatments including hormone depletion, chemotherapy, and radiotherapy. In an effort to determine the therapeutic potential that the inhibition of this protein could have on the development of new strategies for cancer treatment, numerous studies have been carried out in this field, with results, in most cases, satisfactory but sometimes contradictory. In this document, we summarize for the first time the current knowledge of the effects that CLU inhibition has on sensitizing tumor cells to conventional cancer treatments and discuss its importance in the development of new strategies against cancer.

Effect of Targeting Clusterin Using OGX-011 on Antitumor Activity of Temsirolimus in a Human Renal Cell Carcinoma Model

BACKGROUND

It has not been well documented that the modulation of stress response mediates the efficacy of the mammalian target of rapamycin (mTOR) inhibitor in renal cell carcinoma (RCC).

OBJECTIVE

The objective of this study was to investigate whether the activity of the mTOR inhibitor temsirolimus against RCC could be enhanced by OGX-011, an antisense oligodeoxynucleotide (ODN) targeting the stress-activated chaperone clusterin.

METHODS

We investigated the efficacy of combined treatment with temsirolimus plus OGX-011 in a human RCC Caki-1 model focusing on the effects on apoptotic and autophagic pathways.

RESULTS

Although clusterin expression was increased by temsirolims, additional treatment of Caki-1 with OGX-011 significantly inhibited clusterin upregulation (p < 0.05). Combined treatment of temsirolimus and OGX-011 synergistically enhanced the sensitivity of Caki-1 to temsirolimus (p < 0.01), reducing the IC₅₀ by approximately 50 %. Apoptotic changes were marked in Caki-1 following combined treatment with a sublethal dose of temsirolimus and OGX-011, accompanying the significant downregulation of Mcl-1 (p < 0.05), but not with either agent alone. Furthermore, this combined treatment markedly blocked the temsirolimus-induced activation of autophagy in Caki-1 (p < 0.01). In-vivo systemic administration of temsirolimus plus OGX-011 significantly inhibited the growth of Caki-1 tumors compared with that of temsirolimus plus control ODN (p < 0.05).

CONCLUSIONS

Silencing of clusterin using OGX-011 resulted in the further enhancement of proapoptotic activity as well as the marked attenuation of the autophagic pathway induced by temsirolimus in a human RCC model. Thus, the combined use of OGX-011 could be a promising strategy through the enhanced cytotoxic activity of temsirolimus against RCC.

Bladder carcinoma: understanding advanced and metastatic disease with potential molecular therapeutic targets

This article is an expert review of bladder cancer genetics focusing on genetic changes and their significance in the pathogenesis and progression of bladder transitional cell carcinoma, in particular, muscle-invasive disease. Alongside the relevant genetic markers and their products, new therapeutic targets and agents that are being developed are presented.

Clusterin inhibition using OGX-011 synergistically enhances antitumour activity of sorafenib in a human renal cell carcinoma model

BACKGROUND

The objective of this study was to investigate whether the therapeutic activity of sorafenib could be enhanced by combining with OGX-011, an antisense oligodeoxynucleotide (ODN) targeting clusterin, in renal cell carcinoma (RCC).

METHODS

We investigated the effects of combined treatment with OGX-011 and sorafenib on a human RCC ACHN model both in vitro and in vivo.

RESULTS

Although clusterin expression was increased by sorafenib, additional treatment of ACHN with OGX-011 significantly blocked the upregulation of clusterin induced by sorafenib. Despite the lack of a significant effect on the growth of ACHN, OGX-011 synergistically enhanced the sensitivity to sorafenib, reducing the IC(50) by >50%. Apoptotic changes were intensively detected in ACHN after combined treatment with OGX-011 and a sublethal dose of sorafenib, but not either agent alone. Furthermore, this combined treatment resulted in the marked downregulation of phosphorylated Akt and p44/42 mitogen-activated protein kinase in ACHN compared with treatment with either agent alone. In vivo systemic administration of OGX-011 plus sorafenib significantly decreased the ACHN tumour volume compared with control ODN plus sorafenib.

CONCLUSION

Combined use with OGX-011 may be useful in enhancing the cytotoxic effect of sorafenib on RCC by inducing apoptosis and inactivating major signal transduction pathways.

Small interfering RNA targeting heat shock protein 70 enhances chemosensitivity in human bladder cancer cells

OBJECTIVES

To evaluate the expression levels of heat shock protein 70 (HSP70) in human urothelial cancer of the bladder and to assess the therapeutic effects of treatment with small interfering RNA (siRNA) targeting HSP70 on human bladder cancer KoTCC-1 cells.

MATERIALS AND METHODS

HSP70 expression in bladder cancer specimens obtained from 235 patients were evaluated by immunohistochemical staining. We then analyzed changes in the growth and chemosensitivity of KoTCC-1 cells following treatment with HSP70 siRNA.

RESULTS

Expression levels of HSP70 protein in bladder cancer specimens were significantly related to major prognostic indicators, including pathologic stage and tumor grade. Treatment of KoTCC-1 with HSP70 siRNA resulted in a dose-dependent inhibition of HSP70 expression. HSP70 siRNA significantly inhibited the growth of KoTCC-1 compared with that after treatment with scrambled control siRNA. Among several chemotherapeutic agents, the most powerful synergistic cytotoxic effect was observed when KoTCC-1 was treated with gemcitabine plus HSP70 siRNA, which induced more than 50% reduction in the IC50 of gemcitabine. Furthermore, a significant increase in the subG0-G1 fraction of KoTCC-1 and the DNA fragmentation was observed only after combined treatment with HSP70 siRNA and sublethal doses of gemcitabine, but not after treatment with either agent alone. Similarly, caspase-3 and caspase-9, but not caspase-8, in KoTCC-1 were synergistically activated by combined treatment with gemcitabine and HSP70 siRNA.

CONCLUSIONS

Silencing of HSP70 expression using siRNA could be an attractive therapeutic strategy for bladder cancer by inducing inhibition of tumor growth as well as enhancing chemosensitivity.

Growth inhibition and enhanced chemosensitivity induced by down-regulation of Aurora-A in human renal cell carcinoma Caki-2 cells using short hairpin RNA

The objective of this study was to investigate the inhibitory effects of Aurora-A expression on the growth and chemosensitivity of Caki-2 cells in human renal cell carcinoma (RCC). Caki-2 cells were established, in which an expression vector containing short hairpin RNA (shRNA) targeting Aurora-A was introduced (Caki-2/sh-A). The growth and sensitivity of chemotherapeutic agents in Caki-2/sh-A cells were compared to those in Caki-2 cells transfected with control vector alone (Caki-2/C). The expression levels of both Aurora-A mRNA and protein in Caki-2/sh-A cells were less than 10% of those in Caki-2/C cells. The in vitro growth of Caki-2/sh-A cells was significantly inferior to that of Caki-2/C cells, and the proportion of Caki-2/sh-A cells in the G2-M phase was significantly greater compared to that of Caki-2/C cells. In addition, the expression level of Bax in Caki-2/sh-A cells was significantly higher as compared to that in Caki-2/C cells, while phosphorylated Akt in Caki-2/sh-A cells was markedly down-regulated compared to that in Caki-2/C cells. Among several chemotherapeutic agents examined, the most significant difference between Caki-2/sh-A and Caki-2/C cells was observed in the sensitivity to docetaxel. Thus, the IC(50) value of docetaxel in Caki-2/sh-A cells was decreased by approximately 90% compared to that in Caki-2/C cells. Treatment of Caki-2/sh-A cells, but not Caki-2/C ones, with 5 nM docetaxel resulted in the induction of apoptotic cell death accompanying the induction of p53. The findings suggest that the suppression of Aurora-A expression using shRNA is a useful therapeutic strategy against RCC through growth inhibition as well as enhanced chemosensitivity.

Personalized therapy for urothelial cancer: review of the clinical evidence

Despite a detailed understanding of the molecular aberrations driving the development of urothelial cancers, this knowledge has not translated into advances for the treatment of this disease. Urothelial cancers are chemosensitive, and platinum-based combination chemotherapy remains the standard of care for advanced disease, as well as neoadjuvant and adjuvant therapy for locally advanced disease. However, nearly half of patients who undergo resection of locally advanced urothelial cancer will relapse and eventually develop platinum-resistant disease. Clinical trials of targeted agents against angiogenesis and growth factors, as well as novel chemotheraputics, have generally been unsuccessful in urothelial cancers. Improvements in the theraputic arsenal for urothelial cancer depend upon identification of new targets and strategies to overcome platinum resistance.

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.

The role of clusterin (CLU) in malignant transformation and drug resistance in breast carcinomas

Breast cancer is the main cause of cancer-related death among women in Western countries. Current research is focused on identifying antiapoptotic proteins which could be a possible target for novel chemotherapeutic drugs. Secretory clusterin (sCLU) is an extracellular chaperone that has been functionally implicated in DNA repair, cell-cycle regulation, apoptotic cell death and tumorigenesis. The implication of sCLU in carcinogenesis and the progression of breast carcinomas make it an interesting gene, worthy of investigation. It has been reported to present powerful antiapoptotic activity and to perform a prosurvival function with most therapeutic treatments for breast cancer. This review summarizes our current understanding of the role of CLU in tumorigenesis, progression, and response to treatment in breast carcinomas.

Suppressed tumour growth and enhanced chemosensitivity by RNA interference targeting Aurora-A in the PC3 human prostate cancer model

OBJECTIVES

To investigate the inhibitory effects of Aurora-A expression in prostate cancer cells on their growth and chemosensitivity.

PATIENTS AND METHODS

Aurora-A expression in radical prostatectomy specimens obtained from 193 patients were evaluated by immunohistochemical staining. We then established PC3 cells in which the expression vector containing short-hairpin RNA (shRNA) targeting Aurora-A was introduced (PC3/sh-A). The growth and the sensitivity to docetaxel in PC3/sh-A were compared with those in PC3 transfected with control vector alone (PC3/C).

RESULTS

Immunohistochemistry showed that there were various levels of Aurora-A expression in most prostate cancer tissues, and the expression levels of Aurora-A in prostate cancer were significantly related to Gleason score. Expression levels of both Aurora-A mRNA and protein in PC3/sh-A were approximately 20% of those in PC3/C. In vitro growth of PC3/sh-A was significantly worse than that of PC3/C, and the proportion of PC3/sh-A in the G2-M phase was significantly greater than that of PC3/C. The 50% inhibitory concentration of docetaxel in PC3/sh-A decreased by 67% compared with that in PC3/C. Tumour volume in nude mice injected with PC3/sh-A was significantly smaller than that with PC3/C. Furthermore, treatment of nude mice bearing PC3/sh-A tumour with docetaxel (10 mg/kg, once weekly for 4 weeks) achieved a synergistic cytotoxic effect, despite the lack of an enhanced antitumour effect of docetaxel on PC3/C tumours.

CONCLUSIONS

The suppression of Aurora-A using shRNA could be a useful therapeutic strategy against androgen-independent prostate cancer, through growth inhibition as well as enhanced chemosensitivity.

Peptides modulating conformational changes in secreted chaperones: from in silico design to preclinical proof of concept

Blocking conformational changes in biologically active proteins holds therapeutic promise. Inspired by the susceptibility of viral entry to inhibition by synthetic peptides that block the formation of helix-helix interactions in viral envelope proteins, we developed a computational approach for predicting interacting helices. Using this approach, which combines correlated mutations analysis and Fourier transform, we designed peptides that target gp96 and clusterin, 2 secreted chaperones known to shift between inactive and active conformations. In human blood mononuclear cells, the gp96-derived peptide inhibited the production of TNFalpha, IL-1beta, IL-6, and IL-8 induced by endotoxin by >80%. When injected into mice, the peptide reduced circulating levels of endotoxin-induced TNFalpha, IL-6, and IFNgamma by >50%. The clusterin-derived peptide arrested proliferation of several neoplastic cell lines, and significantly enhanced the cytostatic activity of taxol in vitro and in a xenograft model of lung cancer. Also, the predicted mode of action of the active peptides was experimentally verified. Both peptides bound to their parent proteins, and their biological activity was abolished in the presence of the peptides corresponding to the counterpart helices. These data demonstrate a previously uncharacterized method for rational design of protein antagonists.

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.

[The use of p53 as a tool for human cancer therapy]

Tumor suppressor p53 is the central component of a system maintaining the genetic stability of animal and human somatic cells. Its gene is inactivated in almost all human cancers, allowing a tumor cell to rapidly accumulate additional mutations and progress toward a more malignant phenotype. Yet tumor cells are most sensitive to the suppressor effect of p53 when its function is restored. Hence, restoration of the p53 function is an appealing strategy of anticancer therapy. Various mechanisms inactivate p53 in cancer, including point mutations resulting in synthesis of an inactive mutant protein, deletion of the total gene or its portion, damage to the genes involved in regulating the p53 activity, and defects in p53 target genes. In addition, oncogenic viruses code for the specialized proteins that modify the p53 function to ensure optimal replication of the virus genome. These viral proteins are crucial for virus-induced carcinogenesis, in particular, in 95% of cervical carcinoma cases in women. The approaches to p53 activity restoration depend to a great extent on the defect in p53-dependent signaling. Introduction of exogenous p53 is effective in some case and is usually achieved with adenoviral vectors. The approaches under study are aimed at restoring the activity of mutant p53 or suppressing the viral inhibitors of p53. The review considers various schemes involving p53 in cancer therapy and prevention and discusses their potential efficacy and prospects of their clinical use.

Hsp27 knockdown using nucleotide-based therapies inhibit tumor growth and enhance chemotherapy in human bladder cancer cells

Heat shock protein 27 (Hsp27) is a cytoprotective chaperone that is phosphoactivated during cell stress that prevents aggregation and/or regulate activity and degradation of certain client proteins. Recent evidence suggests that Hsp27 may be involved in tumor progression and the development of treatment resistance in various tumors, including bladder cancer. The purpose of this study was to examine, both in vitro and in vivo, the effects of overexpression of Hsp27 and, correspondingly, the down-regulation of Hsp27 using small interfering (si) RNA and OGX-427, a second-generation antisense oligonucleotide targeting Hsp27. Hsp27 overexpression increased UMUC-3 cell growth and resistance to paclitaxel. Both OGX-427 and Hsp27 siRNA decreased Hsp27 protein and mRNA levels by >90% in a dose- and sequence-specific manner in human bladder cancer UMUC-3 cells. OGX-427 or Hsp27 siRNA treatment induced apoptosis and enhanced sensitivity to paclitaxel in UMUC-3 cells. In vivo, OGX-427 significantly inhibited tumor growth in mice, enhanced sensitivity to paclitaxel, and induced significantly higher levels of apoptosis compared with xenografts treated with control oligonucleotides. Collectively, these findings suggest that Hsp27 knockdown with OGX-427 and combined therapy with paclitaxel could be a novel strategy to inhibit the progression of bladder cancer.

Additional Gene Therapy with rAAV-wt-p53 Enhanced the Efficacy of Cisplatin in Human Bladder Cancer Cells

OBJECTIVE

Gene therapy is defined as the treatment of an acquired or inherited disease by transfer of genetic material. The most common strategies in gene therapy of bladder cancer are corrective, inductive and cytotoxic gene therapy. Mutations in the p53 tumor suppressor gene are the most common molecular genetic abnormalities in bladder cancer and p53 gene transfer in the human bladder cancer cell line by adenoviral or other vectors was demonstrated to be cytotoxic. However, so far there has been no report of adeno-associated virus-2 vector-mediated p53 gene deliveries in bladder cancer. In this study, wild-type p53 cDNA was transfected into the bladder cancer cells, using the adeno-associated virus-2 vector, and the capability of rAAV-wt-p53 gene therapy in bladder cancer was evaluated in vitro.

METHOD

Bladder cancer cell lines 5637 were transduced with adeno-associated virus-2 vectors containing wild-type human p53 gene (rAAV-wt-p53). Gene expression and transcriptional activation of p53 was determined by Western blot analysis. The cellular growth inhibition and apoptosis of rAAV-mediated p53 transfection were assessed by flow cytometry. The combination effect of rAAV-wt-p53 and cisplatin was measured by MTT assay.

RESULTS

The virus rAAV efficiently enters the cells and expresses its gene products. The gene product of rAAV-wt-p53 is cytotoxic to bladder cancer cells. The bladder cell line 5637 was found to experience a synergistic killing effect when rAAV-wt-p53 was used in combination with cisplatin.

CONCLUSION

rAAV-mediated p53 gene transfer could offer a powerful novel therapeutic approach in bladder 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.

The potential of clusterin inhibiting antisense oligodeoxynucleotide therapy for prostate cancer

This review summarise the authors' recent experience in the development of antisense (AS) oligodeoxynucleotide (ODN) therapy that targets a cytoprotective gene, clusterin, for the treatment of prostate cancer. The acquisition of resistance to a wide variety of proapototic stimuli was initially demonstrated by introducing the clusterin gene into prostate cancer cells. Furthermore, silencing clusterin expression using AS ODN synergistically enhanced the effects of several conventional therapeutic modalities through the effective induction of apoptosis in prostate cancer xenograft models. Based on these outcomes, Phase I clinical trials were conducted using AS clusterin ODN incorporating 2'-O-(2-methoxy)ethyl-gapmer backbone (OGX-011), and the optimal dose of OGX-011 capable of inducing </= 90% suppression of clusterin in human prostate cancer tissue was determined. Collectively, these findings suggest the utility of inactivating clusterin function using AS ODN technology as a novel therapeutic strategy for prostate cancer treatment. There have been four kinds of Phase II studies that have begun to further evaluate the efficacy of OGX-011 in patients with prostate, breast and lung cancers.

Antisense oligodeoxynucleotide therapy targeting clusterin gene for prostate cancer: Vancouver experience from discovery to clinic

BACKGROUND

The objective of this study was to review our experience in the development of antisense (AS) oligodeoxynucleotide (ODN) therapy for prostate cancer targeting antiapoptotic gene, clusterin.

METHODS

We initially summarized our data demonstrating that clusterin could be an optimal therapeutic target for prostate cancer, then presented the process of developing AS ODN therapy using several preclinical animal models. Finally, the preliminary data of the recently completed phase I clinical trial using AS clusterin ODN as well as the future prospects of this therapy are discussed.

RESULTS

Expression of clusterin was highly up-regulated after androgen withdrawal and during progression to androgen-independence, but low or absent in untreated tissues in both prostate cancer animal model systems and human clinical specimens. Introduction of the clusterin gene into human prostate cancer cells confers resistance to several therapeutic stimuli, including androgen ablation, chemotherapy and radiation. AS ODN targeting the translation initiation site of the clusterin gene markedly inhibited clusterin expression in prostate cancer cells in a dose-dependent and sequence-specific manner. Systemic treatment with AS clusterin ODN enhanced the effects of several conventional therapies through the effective induction of apoptosis in prostate cancer xenograft models. Based on these findings, a phase I clinical trial was completed using AS clusterin ODN incorporating 2'-O-(2-methoxy)ethyl-gapmer backbone (OGX-011), showing up to 90% suppression of clusterin in prostate cancer.

CONCLUSIONS

The data described above identified clusterin as an antiapoptotic gene up-regulated in an adaptive cell survival manner following various cell death triggers that helps confer a phenotype resistant to therapeutic stimuli. Inhibition of clusterin expression using AS ODN technology enhances apoptosis induced by several conventional treatments, resulting in the delay of AI progression and improved survival. Clinical trials using AS ODN confirm potent suppression of clusterin expression and phase II studies will begin in early 2005.

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.