[Show abstract][Hide abstract] ABSTRACT: Docetaxel is the first chemotherapy agent approved for treatment of metastatic castration-resistant prostate cancer (mCRPC). The limited survival benefit associated with the quick emergence of resistance and systemic toxicity diminished its efficacy. JNK-mediated apoptosis is one of the mechanisms of docetaxel activity whereas ERK1/2-c-Myc-CXCR4 signaling is implicated in the development of resistance and induction of migration. The aim of this study was to evaluate the hypothesis that the combination treatment with docetaxel and GLIPR1-ΔTM will synergistically induce greater cell death and inhibit the emergence of resistance and development of metastatic potential in prostate cancer (PCa) cells.
The synergistic effects of the docetaxel and GLIPR1-ΔTM were evaluated with DNA fragmentation, DAPI staining and MTS using paired t-test and isobologram study. The effects of the drugs on JNK and ERK1/2-c-Myc-CXCR4 signaling were evaluated with Western blot, DNA fragmentation, and MTS assays using the JNK inhibitor SP600125, and CXCR4 siRNA. The results of docetaxel and GLIPR1-ΔTM combination on migration were examined with scratch assay using the CXCR4 inhibitor AMD3100 while our hypothesis was examined in vivo using VCaP orthotopic xenograft model.
We found that GLIPR1-ΔΤΜ synergized with docetaxel to induce apoptosis in VCaP and PC-3 PCa cells through induction of JNK signaling and concomitant inhibition of ERK1/2-c-Myc-CXCR4 signaling. We showed that JNK activation mediates the apoptotic effects of the drug combination and that CXCR4 knockdown increases its efficacy. We also found that the addition of GLIPR1-ΔΤΜ to docetaxel decreases the migration of VCaP and PC-3 cells. The combination treatment with docetaxel and GLIPR1-ΔTM inhibited tumor growth and decreased metastatic potential in VCaP xenografts more than single agents did.
Our data suggested that addition of GLIPR1-ΔTM treatment in PCa cells increases the efficacy of docetaxel and may inhibit the emergence of drug resistance; potentially permitting a decrease of docetaxel dose for patients with mCRPC eliminating its systemic toxicities.
[Show abstract][Hide abstract] ABSTRACT: Androgen deprivation is the standard treatment for advanced prostate cancer (PCa), but most patients ultimately develop resistance and tumor recurrence. We found that MYB is transcriptionally activated by androgen deprivation therapy or genetic silencing of the androgen receptor (AR). MYB silencing inhibited PCa growth in culture and xenografts in mice. Microarray data revealed that c-Myb and AR shared a subset of target genes that encode DNA damage response (DDR) proteins, suggesting that c-Myb may supplant AR as the dominant regulator of their common DDR target genes in AR inhibition-resistant or AR-negative PCa. Gene signatures including AR, MYB, and their common DDR-associated target genes positively correlated with metastasis, castration resistance, tumor recurrence, and decreased survival in PCa patients. In culture and in xenograft-bearing mice, a combination strategy involving the knockdown of MYB, BRCA1, or TOPBP1 or the abrogation of cell cycle checkpoint arrest with AZD7762, an inhibitor of the checkpoint kinase Chk1, increased the cytotoxicity of the poly[adenosine 5'-diphosphate (ADP)-ribose] polymerase (PARP) inhibitor olaparib in PCa cells. Our results reveal new mechanism-based therapeutic approaches for PCa by targeting PARP and the DDR pathway involving c-Myb, TopBP1, ataxia telangiectasia mutated- and Rad3-related (ATR), and Chk1.
No preview · Article · May 2014 · Science Signaling
[Show abstract][Hide abstract] ABSTRACT: GLIPR1 is a p53 target gene known to be downregulated in prostate cancer, and increased endogenous GLIPR1 expression has been associated with increased production of reactive oxygen species, increased apoptosis, decreased c-Myc protein levels and increased cell cycle arrest. Recently, we found that upregulation of GLIPR1 in prostate cancer cells increases mitotic catastrophe through interaction with heat shock cognate protein 70 (Hsc70) and downregulation of Aurora kinase A and TPX2. In this study, we evaluated the mechanisms of recombinant GLIPR1 protein (glioma pathogenesis-related protein 1-transmembrane domain deleted [GLIPR1-ΔTM]) uptake by prostate cancer cells and the efficacy of systemic GLIPR1-ΔTM administration in a prostate cancer xenograft mouse model. GLIPR1-ΔTM was selectively internalized by prostate cancer cells, leading to increased apoptosis through reactive oxygen species production and to decreased c-Myc protein levels. Interestingly, GLIPR1-ΔTM was internalized through clathrin-mediated endocytosis in association with Hsc70. Systemic administration of GLIPR1-ΔTM significantly inhibited VCaP xenograft growth. GLIPR1-ΔTM showed no evidence of toxicity following elimination from mouse models 8 hr after injection. Our results demonstrate that GLIPR1-ΔTM is selectively endocytosed by prostate cancer cells, leading to increased reactive oxygen species production and apoptosis, and that systemic GLIPR1-ΔTM significantly inhibits growth of VCaP xenografts without substantial toxicity.
No preview · Article · Apr 2014 · International Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: Objectives:
The objectives of this study are to explore the potential benefits of combining AdGlipr1 (or AdGLIPR1) gene therapy with radiotherapy using subcutaneous prostate and bladder cancer models.
Materials and methods:
Combination adenoviral vector-mediated gene therapy and radiotherapy were applied to 178-2 BMA and TSU-Pr1 cells in vitro and colony formation and apoptosis were analyzed. In addition, combination therapies were administered to mice bearing subcutaneous 178-2 BMA and TSU-Pr1 tumors, and tumor growth suppression and survival extension were compared with the monotherapies (AdGlipr1/AdGLIPR1 and radiotherapy) or control vector Adv/CMV/βgal, as well as single-cycle treatment with 2-cycle treatment.
Combination treatment significantly suppressed colony formation and increased apoptosis in vitro. In vivo, combination therapy produced significant 178-2 BMA and TSU-Pr1 tumor growth suppression and survival extension compared with the monotherapies or the control. Further tumor growth suppression and survival extension were observed after 2 cycles of the combination treatment.
Combining AdGlipr1 (AdGLIPR1) with radiotherapy may achieve additive or synergistic tumor control in selected prostate and bladder tumors, and additional therapeutic effects may result with repeated treatment cycles.
No preview · Article · Feb 2013 · Urologic Oncology
[Show abstract][Hide abstract] ABSTRACT: Caveolin 1 (Cav-1) is a plasma membrane-associated protein with the capacity to modulate signaling activities in a context-dependent fashion. Interactions between Cav-1 and low-density lipoprotein receptor-related protein 6 (LRP6) were reported to be important for the regulation of Wnt-β-catenin (β-cat) signaling. Cav-1 also interacts with insulin and IGF-I receptors (IGF-IR/IR) and can stimulate IR kinase activities. We found positive correlation between Cav-1 and LRP6 expression in both human primary prostate cancer and metastasis tissues and in PC-3 cells. Cav-1 stimulation of Wnt-β-cat signaling and c-Myc levels was positively associated with LRP6 expression in LNCaP, PC-3, and DU145 prostate cancer cells. Importantly, LRP6 and, to a lesser extent, Cav-1 were found to stimulate aerobic glycolysis. These activities were positively associated with the expression of HK2 and Glut3 and shown to be dependent on Akt signaling by both gene knockdown and chemical inhibition methods. We further showed that Cav-1 and LRP6 exert their effects on Akt and glycolytic activities by stimulating IGF-IR/IR signaling. Overall, our results demonstrate that Cav-1 interacts with LRP6 to generate an integrated signaling module that leads to the activation of IGF-IR/IR and results in stimulation of Akt- mTORC1 signaling and aerobic glycolysis in prostate cancer.
[Show abstract][Hide abstract] ABSTRACT: In this study we report that expression of glioma pathogenesis-related protein 1 (GLIPR1) regulated numerous apoptotic, cell cycle, and spindle/centrosome assembly-related genes, including AURKA and TPX2, and induced apoptosis and/or mitotic catastrophe (MC) in prostate cancer (PCa) cells, including p53-mutated/deleted, androgen-insensitive metastatic PCa cells. Mechanistically, GLIPR1 interacts with heat shock cognate protein 70 (Hsc70); this interaction is associated with SP1 and c-Myb destabilization and suppression of SP1- and c-Myb-mediated AURKA and TPX2 transcription. Inhibition of AURKA and TPX2 using siRNA mimicked enforced GLIPR1 expression in the induction of apoptosis and MC. Recombinant GLIPR1-ΔTM protein inhibited AURKA and TPX2 expression, induced apoptosis and MC, and suppressed orthotopic xenograft tumor growth. Our results define a novel GLIPR1-regulated signaling pathway that controls apoptosis and/or mitotic catastrophe in PCa cells and establishes the potential of this pathway for targeted therapies.
[Show abstract][Hide abstract] ABSTRACT: Prostate cancer is characterized by extreme heterogeneity and multifocality of the primary tumour. The available clinical,
pathological and molecular data suggest a lack of substantial clonal expansion at the primary site, yet metastatic progression
of the disease often proceeds in an unpredictable and clinically undetectable fashion. Clinical and experimental data suggest
that primary prostate cancer tumour cells can seed from relatively small tumour foci at the primary site. Overall, this unique
biological pattern of progression presents unique and challenging problems regarding the detection and treatment of the disease.
In general, currently used potentially curative therapies involve a single cytoablative modality (radical prostatectomy or
radiation therapy) and are exclusively directed at the malignant cells within the prostate gland. At present the widespread
use of these treatments has not resulted in substantial reduction in mortality from prostate cancer. Gene therapy used alone
or as an adjuvant approach could, at least conceptually, provide a rational solution for the prostate cancer dilemma. With
gene therapy protocols designed to stimulate antitumour immunity, it may be possible to treat localized and systemic disease
effectively and simultaneously. Our previous preclinical and clinical studies have focused on the use of adenoviral vector-mediated
HSV-tk+GCV (Herpes Simplex Virus thymidine kinase + ganciclovir) in situ gene therapy for prostate cancer. More recently, specific immunomodulatory genes, such as interleukin-12 (IL-12), have been
tested using adenoviral vector-mediated in situ and gene-modified cell based vaccine protocols. The results of these preclinical
studies are promising and demonstrate the possibility of effectively generating cytotoxic activities in localized prostate
cancers through the recruitment of activated immunocytes while generating systemic anti-tumour immunity that results in antimetastatic
activities. We discuss the potential of IL-12 gene therapy for prostate cancer in this review.
[Show abstract][Hide abstract] ABSTRACT: Introduction: We previously documented that adenoviral vector-mediated murine RTVP-1 (AdmRTVP-1) gene therapy significantly suppresses the growth of mouse prostate cancer through direct cytotoxicity and the induction of a systemic anti-tumor immune response. This study explores the potential benefits of combining AdmRTVP-1 or adenoviral vector-mediated human RTVP-1 (AdhRTVP-1) gene therapy with irradiation (XRT) to enhance therapeutic efficacy in a subcutaneous prostate cancer model.Methods: The therapeutic effects of AdmRTVP-1 or AdhRTVP-1 alone or in combination with XRT were evaluated in vitro and in vivo. Tumors were established in 129/Sv adult male mice by subcutaneous inoculation of 5 × 104 178-2 BMA mouse prostate cancer cells. Xenograft tumors were established in athymic nude mice by subcutaneous inoculation of 5 × 106 TSU-Pr1 human prostate cancer cells. The AdmRTVP-1 dose was determined by dose escalation studies using doses from 5 × 107 to 5 × 108 PFU, and the AdhRTVP-1 dose was 5 × 108 PFU. Radiation was administered as a single dose of 5Gy 48hrs after vector injection. Tumor size was monitored every other day and tumor wet weight was determined fourteen days after vector injection. In separate studies, animals with subcutaneous tumors were treated and evaluated for survival benefit.Results: AdmRTVP-1 or AdhRTVP-1 and XRT demonstrated combinatorial effects in vitro as determined by colony formation assay, DAPI staining or FACS analysis of apoptosis. In vivo the optimal dose of AdmRTVP-1 for growth suppression of subcutaneous 178-2 BMA tumors was 5 × 108 PFU. In this model the combination of AdmRTVP-1 + XRT produced statistically significant tumor growth suppression compared to therapy with AdmRTVP-1 alone, control vector Adv/CMV/bgal, or Adv/CMV/bgal + XRT (P < 0.0001, P < 0.0001, P < 0.0001, respectively). In addition significant prolongation in survival to 27.7 days was demonstrated for the combination of AdmRTVP1 + XRT compared with Adv/CMV/bgal (18.1 days, P < 0.0001), Adv/CMV/bgal + XRT (19.4 days, P < 0.0001) or AdmRTVP1 alone (23.6 days, P=0.0350). Xenograft experiments revealed that the combination of AdhRTVP1 + XRT produced statistically significant tumor growth suppression compared to therapy with AdhRTVP-1 alone, control vector Adv/CMV/bgal, or Adv/CMV/bgal + XRT (P < 0.0001, P < 0.0001, P < 0.0001, respectively). Significant prolongation in survival to 132 days was also demonstrated for the combination of AdhRTVP-1 + XRT compared with Adv/CMV/bgal (70 days, P = 0.0042), AdhRTVP-1 alone (80.7 days, P = 0.0245) or Adv/CMV/bgal + XRT (101.2 days, P = 0.0625).Conclusions: Combination in situ AdmRTVP-1 or AdhRTVP-1 gene therapy + XRT significantly suppresses tumor growth and prolongs survival compared to gene or XRT therapy alone. Future studies will be directed at investigating the mechanism of the combined therapeutic effect of AdRTVP-1 gene therapy + XRT.
Full-text · Article · Jan 2004 · Molecular Therapy
[Show abstract][Hide abstract] ABSTRACT: We investigated the efficacy of intratumoral injection of macrophages transduced with murine IL-12 recombinant adenoviral vector (AdmIL-12) using the orthotopic 178-2 BMA mouse prostate cancer model. AdmIL-12-transduced macrophages secreted IL-12 in vitro and demonstrated increased surface expression of MHC classes I and II as well as F4/80 antigen compared with uninfected macrophages or those infected with an adenoviral vector containing beta-galactosidase (Adbetagal) in control macrophages. AdmIL-12-transduced macrophages injected into orthotopic 178-2 BMA tumors in vivo induced significant suppression of primary tumor growth and spontaneous lung metastases compared with controls. These antitumor and antimetastatic effects were comparable with those resulting from direct orthotopic delivery of the AdmIL-12 vector. Mice with orthotopic tumors treated with AdmIL-12-transduced macrophages survived significantly longer than controls. Analysis of tumors demonstrated significantly increased infiltration of CD4+ and CD8+ T cells in those injected with AdmIL-12-transduced macrophages compared with controls. Splenocyte-derived cytotoxic natural killer cell activity was enhanced on day 2 after AdmIL-12-transduced macrophage injection, and on day 14, tumor-specific T-lymphocyte activities were increased compared with control, Adbetagal-infected macrophages. Trafficking studies confirmed that intratumorally injected, AdmIL-12-transduced macrophages could migrate to draining lymph nodes. Overall, this novel approach to prostate cancer therapy demonstrates antitumor immune responses that provide effective antimetastatic activities in preclinical studies.
[Show abstract][Hide abstract] ABSTRACT: We previously identified the mouse RTVP-1 (mRTVP-1; related to testes-specific, vespid, and pathogenesis proteins) gene as a direct target of p53 with proapoptotic activities in various cancer cell lines, including prostate cancer. To test the therapeutic potential of mRTVP-1 we constructed an adenoviral vector capable of efficient transduction and expression of mRTVP-1 (AdmRTVP-1) and used this vector in an orthotopic, metastatic mouse model of prostate cancer. A single intratumoral administration of AdmRTVP-1 gene therapy significantly reduced primary tumor wet weight compared with control Adbetagal-injected tumors at two time points after injection with two different vector doses (p < or = 0.01 at 7 and 14 days). Spontaneous metastasis to lung was also significantly reduced (p < or = 0.02). Evaluation of treated tumors revealed increased apoptosis and lower microvessel density counts. In a rat aortic ring sprouting assay, AdmRTVP-1 inhibited endothelial cell sprouting compared with Adbetagal, confirming its antiangiogenic activity. These therapeutic activities were associated with a significant increase in survival from 22.9 to 26.8 days (p = 0.003) in this aggressive model of prostate cancer. Interestingly, there were significant increases in the infiltration of tumor-associated macrophages, dendritic cells, and CD8+ T cells, which persisted at 14 days posttreatment in the AdmRTVP-1-treated tumors compared with Adbetagal control-treated tumors. In addition, significantly increased natural killer and cytotoxic T lymphocyte activities were demonstrated in the mice with AdmRTVP-1-treated tumors. The unique therapeutic properties of AdmRTVP-1 gene therapy demonstrated in this study provide new opportunities for gene and immunotherapy of prostate cancer and potentially other malignancies.
No preview · Article · Jan 2003 · Human Gene Therapy
[Show abstract][Hide abstract] ABSTRACT: We identified a novel mouse gene, mRTVP-1, as a p53 target gene using differential display PCR and extensive promoter analysis. The mRTVP-1 protein has 255 amino acids and differs from the human RTVP-1 (hRTVP-1) protein by two short in-frame deletions of two and nine amino acids. RTVP-1 mRNA was induced in multiple cancer cell lines by adenovirus-mediated delivery of p53 and by gamma irradiation or doxorubicin both in the presence and in the absence of endogenous p53. Analysis of RTVP-1 expression in nontransformed and transformed cells further supported p53-independent gene regulation. Using luciferase reporter and electrophoretic mobility shift assays we identified a p53 binding site within intron 1 of the mRTVP-1 gene. Overexpression of mRTVP-1 or hRTVP-1 induced apoptosis in multiple cancer cell lines including prostate cancer cell lines 148-1PA, 178-2BMA, PC-3, TSU-Pr1, and LNCaP, a human lung cancer cell line, H1299, and two isogenic human colon cancer cell lines, HCT116 p53(+/+) and HCT116 p53(-/-), as demonstrated by annexin V positivity, phase-contrast microscopy, and in selected cases 4',6'-diamidino-2-phenylindole staining and DNA fragmentation. Deletion of the signal peptide from the N terminus of RTVP-1 reduced its apoptotic activities, suggesting that a secreted and soluble form of RTVP-1 may mediate, in part, its proapoptotic activities.
Full-text · Article · Jun 2002 · Molecular and Cellular Biology
[Show abstract][Hide abstract] ABSTRACT: We have documented previously that adenovirus-mediated interleukin 12 (IL-12) gene therapy is effective for orthotopic tumor control and suppression of pre-established metastases in a preclinical prostate cancer model (Y. Nasu et al., Gene Ther., 6: 338-349, 1999). In this report, we directly compare the effectiveness of an adenovirus that expresses both IL-12 and the costimulatory molecule B7-1 (AdmIL12/B7) with one that expresses IL-12 alone (AdmIL-12) using the poorly immunogenic RM-9 orthotopic murine model of prostate cancer. We document AdmIL-12/B7-mediated secretion of IL-12 and increased surface expression of B7-1 in infected RM-9 tumor cells. A significant reduction in orthotopic tumor size and increased survival was demonstrated in mice treated with a single orthotopic injection of AdmIL-12/B7 compared with AdmIL-12 or controls. Six of 19 animals treated with AdmIL-12/B7 survived long term with apparent eradication of the primary tumor in contrast to one of 38 animals in the AdmIL-12-treated group. Orthotopic treatment of tumors with both vectors led to an infiltration of both CD4+ and CD8+ immunoreactive cells, with AdmIL-12/B7 treatment having a more prolonged infiltration of CD8+ cells. AdmIL-12/B7 was also more effective than AdmIL-12 or controls at suppression of pre-established metastases. We further developed a vaccine model based on s.c. injection of infected, irradiated RM-9 cells and found that both AdmIL-12 and AdmIL-12/B7 are effective at suppressing the development and growth of challenge orthotopic tumors using this protocol.
No preview · Article · Nov 2000 · Clinical Cancer Research
[Show abstract][Hide abstract] ABSTRACT: Recent data indicating that overexpression of caveolin-1 as well as c-myc are relatively common features of advanced prostate cancer prompted us to test for potential cooperative interactions between caveolin-1 and c-myc that would be consistent with malignant progression. We used the well-characterized Rat1AmycERT cells to show that the caveolin-1 gene is down-regulated at the level of transcription by c-myc. By maintaining relatively high levels of caveolin-1 with an adenoviral vector or in stably transfected clones we show that caveolin-1 can suppress c-myc-induced apoptosis. Further we established human prostate cancer cell lines with the mycER construct and show that clones with increased caveolin-1 are more resistant to myc-induced apoptosis and have increased capacity for growth in soft agar when c-myc is activated.
[Show abstract][Hide abstract] ABSTRACT: Although prostate cancer cells are often initially sensitive to androgen ablation, they eventually lose this response and continue to survive, grow and spread in the absence of androgenic steroids. The mechanism(s) that underlie resistance to androgen ablation therapy remain mostly unknown. We have demonstrated that elevated caveolin protein levels are associated with human prostate cancer progression in pathological specimens. Here we show that suppression of caveolin expression by a stably transfected antisense caveolin-1 cDNA vector converted androgen-insensitive metastatic mouse prostate cancer cells to an androgen-sensitive phenotype. Orthotopically grown tumors and low-density cell cultures derived from antisense caveolin clones had increased apoptosis in the absence of androgenic steroids, whereas similarly grown tumors and cells from vector (control) clones and parental cells were not sensitive to androgens. Studies using a representative antisense caveolin clone showed that selection for androgen resistance in vivo correlated with increased caveolin levels, and that adenovirus-mediated caveolin expression blocked androgen sensitivity. Our results identify a new candidate gene for hormone-resistant prostate cancer in man and indicate that androgen insensitivity can be an inherent property of metastatic prostate cancer.