Prostate Cancer Gene Therapy Research Articles

Phase I clinical trial of interleukin 2 (IL-2) gene therapy for prostate cancer.

Phase I clinical trial of interleukin 2 (IL-2) gene therapy for prostate cancer.

New Prospectives of Prostate Cancer Gene Therapy: Molecular Targets and Animal Models

Prostate cancer is the most common cancer and the second leading cause of cancer-related death among North American men. The low cure rate for prostate cancer is associated with the fact that many patients have metastatic disease at the time of disease presentation. Currently available therapeutic modalities for prostate cancer, such as surgery, radiation, hormone therapy, and chemotherapy, have failed to cure patients because these therapies are not sufficiently tumor-specific, resulting in dose-limiting toxicity. Therefore, gene therapy may offer great promise in this regard. In this article, we summarize current advances in gene therapy technologies for the treatment of cancer in general, and future prospects for treatment of human prostate cancer metastasis. We specifically emphasize current studies for improvement, both in the efficiency and the specificity of viral and nonviral vectors, and restricted transgene expression in tumors, to achieve selective targeting with minimized host organ toxicity, based on the molecular understanding of potential regulatory differences between normal and tumor cells. Cell and animal models used to study prostate cancer growth, invasion, and metastasis, and their usefulness in preclinical evaluation of therapeutic vectors in the treatment of prostate cancer skeletal metastasis are also discussed.

Adenoviral mediated gene therapy for prostate cancer: studies on vector tropism and payload.

Adenoviral mediated gene therapy for prostate cancer: studies on vector tropism and payload

Isolation and Characterization of the Promoter of the Human Prostate Cancer-specific DD3 Gene

Recently, we have described a novel gene, DD3, which is one of the most prostate cancer-specific genes described to date (Bussemakers, M. J. G., van Bokhoven, A., Verhaegh, G. W., Smit, F. P., Karthaus, H. F. M., Schalken, J. A., Debruyne, F. M. J., Ru, N., and Isaacs, W. B. (1999) Cancer Res. 59, 5975-5979). The prostate cancer-specific expression of DD3 indicates that the DD3 gene promoter is a promising tool for the treatment of prostate cancer. To identify the promoter elements that are responsible for the prostate cancer-specific expression of DD3, we have isolated and characterized the DD3 promoter. Sequence analysis of the DD3 5'-flanking region was performed and several promoter-human growth hormone reporter constructs were prepared, which were transiently transfected in the DD3-positive cell line LNCaP and several DD3-negative cell lines. Using a 500-base pair DD3 promoter construct, we could detect promoter activity in LNCaP cells, which was not affected by increasing the size of the constructs. Truncated constructs, however, showed an increased transcriptional activity, suggesting the presence of a silencer that negatively regulates the expression of DD3. DNase-I footprint analysis, using nuclear extracts from LNCaP cells, revealed the presence of three DNase-I-protected areas within the DD3 proximal promoter. We show that the high mobility group I(Y) protein binds to one of the DNase-I-protected areas and recruits another, yet unidentified, protein to the DD3 promoter in LNCaP cells.

Tumour angiogenesis as a target for adenoviral mediated antisense gene therapy in human prostate cancer.

Tumour angiogenesis as a target for adenoviral mediated antisense gene therapy in human prostate cancer

Targeting of adenoviral vectors for gene therapy of prostate cancer.

The transduction of cytotoxic genes by adenoviral vectors into prostatic cells offers a new entity for the treatment of prostate cancer. Current adenoviral vectors cannot infect prostatic cells selectively, and expression of therapeutic genes is often too low to be efficient. Bispecific antibodies may alter the natural tropism of adenoviral vectors towards prostatic cells, and increase the efficacy of infection (transductional targeting). The transcription of transgenes can be placed under the control of prostate-specific promoters (transcriptional targeting), and the combination of this with transductional targeting may be warranted to construct targeted vectors that are adequate for gene therapy of the prostate. Prostate Cancer and Prostatic Diseases (2000) 3, 308-312

The application of an anti-angiogenic gene (thrombospondin-1) in the treatment of human prostate cancer xenografts.

Angiogenesis is a critical event for solid tumor growth and metastasis. Within a given microenvironment, the angiogenic response is determined in part by the balance between angiogenesis inducers and inhibitors. The aim of this study was to establish a thrombospondin-1 (TSP-1) ( an antiangiogenic gene) expression vector, and to determine the feasibility for use of TSP-1 in prostate cancer gene therapy. The results of this study showed that pCR-TSP-1, the cloned TSP-1 expression plasmid vector, expressed the TSP-1 gene efficiently in DU145, a human prostate cancer cell line. pCR -TSP-1 did not exert any significant growth inhibitory activity on the tested cell line in vitro. However, TSP-1 overexpression inhibited the growth of DU-145 xenografts in Balb/c nude mice when directly transfected with pCR-TSP-1 in combination with a liposomal agent (DOSPER). Histological analysis showed that there were extensive areas of necrosis in the TSP-1 overexpressing tumors, whereas no necrotic foci were observed in the control tumors. Furthermore, the microvessel density was lower in the TSP-1 overexpressing tumors compared to the control tumors. These results suggest that TSP-1 may be a potentially useful gene for prostate cancer gene therapy.

Towards the optimal vector for prostate cancer gene therapy; a caPCURE meeting report.

Towards the optimal vector for prostate cancer gene therapy; a caPCURE meeting report.

Cytopathic effect of in situ gene therapy in prostate cancer

This is a morphologic study of in situ gene therapy effects in patients with prostate cancer using the Herpes Simplex Virus-Thymidine Kinase gene (HSV-tk) followed by ganciclovir. Prostatectomy specimens from the first 4 patients showed the following morphologic changes: (1) various degrees of necrosis were seen in cancer foci; (2) cytopathic changes were seen across the whole spectrum of Gleason grades; (3) the normal prostate was rarely affected by necrosis, but contained an intense mononuclear infiltrate; (4) loss of nuclear detail was a common finding. Volumetric studies showed that only portions of the tumor show morphologic effects as well as an inverse relationship between percentage of affected tumor and prostate and tumor size. An inflammatory response was observed, with predominance of CD20-positive cells in normal prostate tissue, CD8 (cytotoxic T cells) in the tumor, and macrophages in all areas of the treated prostates. We believe that these changes represent the cytopathic effect of our in situ gene therapy on prostate cancer, and that they trigger a local immune response. HUM PATHOL 31:804-812.

Targeting and eradicating cancer cells by a prostate-specific vector carrying the diphtheria toxin A gene.

Prostate cancer is the most commonly diagnosed malignancy in American men. Developing gene therapy for prostate cancer is important, because there is no effective treatment for patients in the advanced stages of this disease. A tissue-specific promoter to transcriptionally target cancer cells is a promising approach for gene therapy of prostate cancer. We previously constructed a prostate tissue-specific promoter based on the proximal promoter and the upstream regulatory sequence of the prostate-specific antigen gene. In the experiments described here, we modified our prostate-specific promoter to drive the A domain of the diphtheria toxin gene (DTA) in a plasmid vector. The plasmid vector can be efficiently transfected into cell lines, using a liposome-mediated transfection method. In the transfected prostate cell line, LNCaP, the DTA gene was actively transcribed, and significant inhibition of protein synthesis and cytopathic effects was observed. However, no pathogenic effects were apparent in the control cell lines. The highly specific and efficient cytopathicity of the DTA gene vector is therefore potentially useful for systemic treatment of patients with metastatic prostate cancer.

Tissue-specific promoters in gene therapy for the treatment of prostate cancer.

Delivery of therapeutic toxic genes to and their expression in tumor cells through the use of tissue-specific promoters could decrease their toxic effect on neighboring normal cells when virus-mediated gene delivery results in their infection. We have demonstrated the utility of two prostate cancer-specific promoters, long PSA and osteocalcin, for tissue-specific toxic gene therapy for prostate cancer. The two promoters were highly active in both androgen-dependent and androgen-independent prostate cancer cells. We also introduce the Phase I trial of osteocalcin promoter-based toxic gene therapy for bone metastases of prostate cancer, which is in progress at the University of Virginia.

Adenovirus p16 gene therapy for prostate cancer.

Surgery, radiation, or hormone deprivation alone does not adequately affect local control of clinical or pathologic stage T3 prostate cancer. Lack of local cancer control ultimately leads to a higher incidence of morbidity, distant metastasis, and decreased survival, with patients having disease-specific mortality exceeding 75%. Other novel therapies against this devastating and common disease are needed for the achievement of long-term local cancer control. For this purpose, therapeutic interventions should target prostate-cancer cells at the molecular and cellular level in ways not possible by current modalities of cancer treatment. Any strategy that can modify the biologic behavior of these cells may potentially have the most significant clinical impact. As prostate cancer represents an accumulation of genetic mutations that causes a prostate cell to lose the ability to control its growth, one new approach against prostate cancer may be gene therapy. Identification of key missing or mutated tumor-suppressor genes that, when replaced, may inhibit or destroy prostate-cancer cells may have the best chance of clinical success. One such gene appears to be tumor-suppressor gene p16 (also known as MTS1, INK4A, and CDKN2). Tumor-suppressor gene p16 is an important negative cell-cycle regulator whose functional loss may significantly contribute to malignant transformation and progression. Alterations in the p16 gene and its protein expression often occur in prostate cancer. An adenoviral vector containing wild-type p16 (Adp16) had a high transduction efficiency in prostate-cancer cells both in vitro and in vivo. Moreover, prostate tumors injected with Adp16 expressed p16 and the adenoviral vector expressed the transgene for up to 14 days. Wild-type p16 inhibited prostate-cancer proliferation in vitro and markedly suppressed tumors in vivo. Pathologic evaluation of the Adp16-treated tumors showed dose-dependent necrosis and fibrosis. Although the mechanism of p16 inhibition in cancer remains to be elucidated, senescence and apoptosis may both be important; however, the data suggest that p16-induced growth inhibition can function independently of the retinoblastoma gene product.

Prospects for herpes-simplex-virus thymidine-kinase and cytokine gene transduction as immunomodulatory gene therapy for prostate cancer

In completed and ongoing clinical trials, adenovirus-mediated (Ad.) expression of herpes-simplex-virus thymidine-kinase (HSV-tk) gene transduction followed by ganciclovir (GCV) therapy has produced limited toxicity and evidence of antitumor activity following injection of the prostate. Furthermore, this system has been shown to direct systemic antitumor activity in several experimental cancer models, including that of prostate cancer, which may serve as the basis for in-situ immunomodulatory gene therapy. In a mouse model of prostate cancer, natural killer (NK) cells have been identified as the mediator of antimetastatic activity following Ad.HSV-tk + GCV, resulting in the combination of Ad.HSV-tk and adenovirus-mediated expression of interleukin 12 (Ad.IL-12) to exploit this cytokine's ability to enhance NK proliferation and cytotoxicity. Combination therapy demonstrated superior local and systemic growth suppression over that obtained with either therapy alone. Importantly, when the metastatic tumor burden was increased to an extent that negated the growth-suppressive activity directed by Ad.HSV-tk + GCV or Ad.IL-12 alone, combination therapy continued to demonstrate significant growth suppression. Examination of tumor-infiltrating lymphocytes documented enhanced NK lytic activity following combination therapy. Therefore, it appears that the combination of Ad.HSV-tk and Ad.IL-12 should be validated in a clinical trial for the treatment of prostate cancer.

Gene therapy for prostate cancer at the University of California, Los Angeles: preliminary results and future directions.

The treatment options for patients with advanced prostate cancer are limited. Because of recent advances in the understanding of the molecular biology of prostate cancer, the accessibility of the prostate for injection, and the availability of gene promotors that allow tissue-specific expression of therapeutic gene products, gene therapy for prostate cancer has realized significant achievements in recent years. What once belonged to the realm of basic science is now entering the domain of phase II clinical trials. In this review, current results and future directions in prostate gene therapy at the University of California, Los Angeles, are discussed.

Adenoviral vector containing wild-type p16 suppresses prostate cancer growth and prolongs survival by inducing cell senescence.

It is estimated that there will be >184,500 new cases of prostate cancer and 42,000 prostate cancer deaths in the United States this year. In the majority of patients diagnosed with prostate cancer, the disease will be too advanced for cure with standard medical treatment. New therapeutic strategies against advanced prostate cancer are desperately needed. As alterations in tumor-suppressor gene p16 are common in prostate cancer, one novel approach is gene therapy using a replication-deficient, E1/E3-deleted adenovirus type 5 containing a p16 under the control of a truncated Rous sarcoma virus promoter (AdRSVp16). In vitro, PC-3 cells that had been stably transfected with p16 expression vector under the control of an inducible promoter had a 70% reduction in cell number compared with the parental and control vector-transfected PC-3 cells. Similarly, AdRSVp16 significantly inhibited the growth of PPC-1 and PC-3 prostate cancer cells in culture. Furthermore, PPC-1 tumors grown in nude mice treated by a single injection of AdRSVp16 had a marked reduction in tumor size compared with untreated control-treated or viral control-treated PPC-1 tumors. Animals bearing tumors treated with AdRSVp16 also had longer survival. Adenovirally mediated expression of transgene was detected in xenograft tumors for at least 2 weeks. Taken together, these results suggest that AdRSVp16 should be considered for prostate cancer gene therapy in human clinical trials.

A Novel Adenoviral Vector Regulated by the Caveolin-1 Promoter for in Situ Prostate Cancer Gene Therapy

A Novel Adenoviral Vector Regulated by the Caveolin-1 Promoter for in Situ Prostate Cancer Gene Therapy

Combined suicide gene therapy and radiotherapy for prostate cancer: A phase I study

Combined suicide gene therapy and radiotherapy for prostate cancer: A phase I study

Baculoviruses as Vectors for Gene Therapy against Human Prostate Cancer.

Current curative strategies for prostate cancer are restricted to the primary tumour, and the effect of treatments to control metastatic disease is not sustained. Therefore, the application of gene therapy to prostate cancer is an attractive alternative. Baculoviruses are highly restricted insect viruses, which can enter, but not replicate in mammalian cells. Baculoviruses can incorporate large amounts of extra genetic material, and will express transgenes in mammalian cells when under the control of a mammalian or strong viral promoter. Successful gene delivery has been achieved both in vitro and in vivo and into both dividing and nondividing cells, which is important since prostate cancers divide relatively slowly. In addition, the envelope protein gp64 is sufficiently mutable to allow targeted transduction of particular cell types. In this review, the advantages of using baculoviruses for prostate cancer gene therapy are explored, and the mechanisms of viral entry and transgene expression are described.

Transductional targeting of adenoviral vectors to prostate cancer in vitro.

Adenovirus-mediated cytotoxic gene therapy for prostate cancer offers a new therapeutic modality. Currently, intraprostatic injection is used to target vectors to the prostate. Transcriptional targeting of genes under the control of prostate-speci®c promoters had been shown to be speci®c, but is limited by a low expression. Increasing the transduction of the vector (Adv) into the cell might increase the expression of therapeutic genes. The adenovirus uses the Coxsackie adenoviral receptor (CAR) to adhere to the cell membrane by means of its viral knob, after which internalisation occurs under the in uence of integrins. Many tumour cells have limited or absent CAR. We have evaluated the possibility of retargeting adenoviral vectors towards the pantumoral EpCAM antigen and the ®broblast growth factor receptor (FGFR) in order to increase transduction in vitro.

GENE THERAPY FOR PROSTATE CANCER: New Perspectives on an Old Problem

Recent advances in molecular biology have made the prospect of gene therapy for prostate cancer a reality. A wide variety of genetic strategies, vector designs, and delivery modalities are currently in use. This article examines the state of the art prostate cancer gene therapy and details the various options available to clinicians.