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Biomedical subjects

J W Simons

Publications and source records attributed to J W Simons.

At least 55 records · Page 3Linked to original sources
PubMed1997

Prostate attenuated replication competent adenovirus (ARCA) CN706: a selective cytotoxic for prostate-specific antigen-positive prostate cancer cells.

Prostate-specific antigen (PSA) is a widely used marker for the diagnosis and management of prostate cancer. Minimal enhancer/promoter constructs derived from the 5' flank of the human PSA gene (prostate-specific enhancer) were inserted into adenovirus type 5 DNA so as to drive the E1A gene, thereby creating a prostate-specific enhancer-containing virus, CN706. E1A was expressed at high levels in CN706-infected human PSA-producing LNCaP cells but not in CN706-infected DU145 cells, which are human prostate cells that do not express PSA. The titer of CN706 was significantly higher in LNCaP cells compared to several human cell lines that do not produce PSA (HBL100, PANC-1, MCF-7, DU145, and OVCAR3). Furthermore, in LNCaP cells, the yield of CN706 was dependent on exogenous androgen (R1881). CN706 destroyed large LNCaP tumors (1 x 10(9) cells) and abolished PSA production in nu/nu mouse xenograft models with a single intratumoral injection.

Adenovirus E1A Proteins↗
PubMed1997

Bioactivity of autologous irradiated renal cell carcinoma vaccines generated by ex vivo granulocyte-macrophage colony-stimulating factor gene transfer.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) gene-transduced, irradiated tumor vaccines induce potent, T-cell-mediated antitumor immune responses in preclinical models. We report the initial results of a Phase I trial evaluating this strategy for safety and the induction of immune responses in patients with metastatic renal cell carcinoma (RCC). Patients were treated in a randomized, double-blind dose-escalation study with equivalent doses of autologous, irradiated RCC vaccine cells with or without ex vivo human GM-CSF gene transfer. The replication-defective retroviral vector MFG was used for GM-CSF gene transfer. No dose-limiting toxicities were encountered in 16 fully evaluable patients. GM-CSF gene-transduced vaccines were equivalent in toxicity to nontransduced vaccines up to the feasible limits of autologous tumor vaccine yield. No evidence of autoimmune disease was observed. Biopsies of intradermal sites of injection with GM-CSF gene-transduced vaccines contained distinctive macrophage, dendritic cell, eosinophil, neutrophil, and T-cell infiltrates similar to those observed in preclinical models of efficacy. Histological analysis of delayed-type hypersensitivity responses in patients vaccinated with GM-CSF-transduced vaccines demonstrated an intense eosinophil infiltrate that was not observed in patients who received nontransduced vaccines. An objective partial response was observed in a patient treated with GM-CSF gene-transduced vaccine who displayed the largest delayed-type hypersensitivity conversion. No replication-competent retrovirus was detected in vaccinated patients. This Phase I study demonstrated the feasibility, safety, and bioactivity of an autologous GM-CSF gene-transduced tumor vaccine for RCC patients.

Adult↗
PubMed1996

The lipase from Staphylococcus aureus. Expression in Escherichia coli, large-scale purification and comparison of substrate specificity to Staphylococcus hyicus lipase.

The genes coding for the mature part of the lipases from Staphylococcus aureus NCTC8530 and Staphylococcus hyicus have been cloned and overexpressed in Escherichia coli as fusion proteins with an N-terminal hexa-histidine tag. The enzymes accumulated in the cytoplasm and were purified using sequential precipitation with protamine sulphate and ammonium sulphate, followed by metal-affinity and hydroxyapatite chromatography. The yield of pure lipase was 4.5 mg/g wet cells for S. aureus lipase and 13 mg/g for S. hyicus lipase. The purified enzymes need calcium for activity, albeit with different affinities, and a low residual activity was found in the absence of calcium. In contrast to S. hyicus lipase, not only strontium but also barium can replace calcium with full retention of activity of S. aureus lipase. Whereas S. hyicus lipase is optimally active at pH 8.5, the optimum pH for enzymatic activity for S. aureus lipase was found to be pH 6.5. The S. aureus lipase has a narrow substrate specificity: short-chain triacylglycerols and acyl esters of both p-nitrophenol and umbelliferone are readily degraded, whereas medium- and long-chain lipids, as well as phospholipids, are poor substrates. In contrast, S. hyicus lipase prefers phospholipids as substrate and hydrolyses neutral lipids irrespective of their chain length. The results are discussed in view of the large sequence similarity between both lipases.

Esters↗
PubMed1996

Nongenotoxic carcinogens: development of detection methods based on mechanisms: a European project.

While the accumulation of genetic changes in a somatic cell is considered essential for the genesis of a cancer, it has become clear that not all carcinogens are genotoxic, suggesting that some carcinogens indirectly participate in the generation of genetic changes during carcinogenesis. A European project funded by the European Community was thus conceived to study mechanisms of nongenotoxic aspects of carcinogenesis. Two main strategical approaches were adapted: (i) to study whether and how Syrian hamster embryo (SHE), Syrian hamster dermal (SHD) and BALB/c 3T3 cell transformation systems simulate in vivo carcinogenesis, and to examine whether they can detect nongenotoxic carcinogens; (ii) to study, refine and validate mechanisms-based end-points for detection of nongenotoxic carcinogens. For mechanisms-based research, the proposed end-points included gap junctional intercellular communication (GJIC) inhibition, altered expression of critical genes, immortalization and aberrant cell proliferation. We also selected model compounds commonly usable for various endpoints. Our major results can be summarized as follows: (1) SHE and BALB/c 3T3 transformation systems reflect both genotoxic and nongenotoxic carcinogenic events; they detect not only genotoxic but also many although not all, nongenotoxic carcinogens. This is further supported by the fact that both genotoxic and nongenotoxic carcinogens were able to immortalize SHD cells. (2) Many nongenotoxic carcinogens, although not all, inhibit GJIC in vitro as well as in vivo. Mechanistic studies suggest an important role of blocked GJIC in carcinogenesis and that different mechanisms are involved in inhibition of the communication by different agents used. However, inhibition of GJIC is not a prerequisite for the enhancement (or induction) of transformation of SHE or BALB/c 3T3 cells. (3) Among compounds examined, there was a good correlation between induction of micronuclei and cell transformation in SHE cells while no such correlation was found between the induction of cell transformation and ornithine decarboxylase activity. (4) Two transgenic mouse mutation assays (lacI and lacZ) were established and validated. The genotoxin dimethylnitrosamine was shown to be mutagenic to the liver in both assays. Ortho-anisidine, a bladder-specific carcinogen that was inactive in standard rodent genetic toxicity assays was uniquely mutagenic to the bladder of the transgenic mice. The peroxisome proliferator methyl clofenipate was established as nonmutagenic to the liver of both transgenic mice. That eliminated DNA damage as a cause of the liver tumours produced by this chemical and weakened the idea that induced cell division leads to mutation induction. (5) With an in vitro DNA replication model, it was found that DNA damage induced by genotoxic agents can be responsible for inhibition of DNA replication, while certain nongenotoxic agents such as phorbol esters increase DNA replication. (6) An attempt to use structure-activity relationship for subfamilies of nongenotoxic carcinogens, e.g., receptor-mediated carcinogens, has been initiated with some promising results. Our results support the idea that there are multiple nongenotoxic mechanisms in carcinogenesis, and that working hypothesis-oriented approaches are encouraged rather than simple screening of chemicals in developing test systems for the detection of nongenotoxic carcinogens.

3T3 Cells↗
PubMed1996

Endothelin-1 production and decreased endothelin B receptor expression in advanced prostate cancer.

The potent vasoconstrictor endothelin-1 (ET-1) is at its highest concentration in the normal human ejaculate and is associated with the progression of metastatic prostate cancer. ET-1 protein expression is detected in situ in 14 of 14 primary cancers and 14 of 16 metastatic sites of human prostatic carcinoma. Exogenous ET-1 induces prostate cancer proliferation directly and enhances the mitogenic effects of insulin-like growth factor I, insulin-like growth factor II, platelet-derived growth factor, basic fibroblast growth factor, and epidermal growth factor in serum-free conditions in vitro. The ETA-selective receptor antagonist A-127722 inhibits ET-1-stimulated growth, but the ETB-selective receptor antagonist BQ-788 does not. ET-3, an ETB-selective agonist, also had no effect on prostate cancer growth. No specific ETB-binding sites could be demonstrated in any established human prostate cancer cell line tested, and ETB mRNA, detected by reverse transcription PCR, was reduced. The predominance of ETB binding on human benign prostatic epithelial tissue is not present in metastatic prostate cancer by autoradiography. In human prostate cancer progression to metastases, ET-1 and ETA expression are retained, whereas ETB receptor expression is reduced.

Apoptosis↗
PubMed1996

New approaches to adjuvant therapy for patients with adverse histopathologic findings following radical prostatectomy.

Some men affected with clinically localized prostate carcinoma suffer life-threatening recurrence, despite previous treatment with surgery or radiation therapy, underscoring the need for new, effective, systemic adjuvant treatment approaches. Recent molecular mechanism-based prostate cancer drug discovery efforts have identified several candidate targets for systemic prostate cancer adjuvant therapy; however, traditional cancer treatment development algorithms may not be appropriate for many of the new treatment strategies. To best exploit the clinical potential of these molecular treatment strategies, novel translational research strategies are required to support hypothesis-driven clinical research and development.

Antineoplastic Agents↗
PubMed1996

Prostate cancer treatment strategies based on tumor-specific biological principles: future directions.

Prostate cancer represents a heterogeneous disease entity with varying degrees of behavior, aggressiveness, patterns of metastasis, and response to therapy. Progressive metastatic prostate cancer is associated with a formidable array of morbidity that ultimately contributes to death of the patient. Thus far, there has been no convincing evidence to support routine use of non-hormonal chemotherapeutic agents or combinations over symptomatic treatment only. Furthermore, no single compound or combination has shown a dramatic improvement in conventional quality of life parameters over symptomatic treatment only. Androgen ablation remains the primary systemic therapeutic modality for this disease, yet the intense delineation of mechanisms involved in tumor cell metastasis has lead to new therapeutic strategies, ranging from cytotoxic to cytostatic, including immunomodulators. Among those strategies currently being studied are granulocyte-macrophage colony-stimulating factor-transduced prostate cancer vaccines, differentiation therapy, gene therapy, inducers of apoptosis, antimetastatic agents, angiogenesis inhibitors, radiation therapy (local and systemic), and systemic approaches targeted at prostate cancer morbidity. The difficult issue is which agents should be developed and how should we best assess the response using standard and newly identified endpoints. Certainly, the future of advanced prostate cancer therapy will undergo dramatic changes as a result of the continued interaction between the laboratory and the clinic.

Antineoplastic Agents↗
PubMed1996

Phenylbutyrate induces apoptosis in human prostate cancer and is more potent than phenylacetate.

Phenylbutyrate (PB), a novel lead compound for prostate cancer therapy, has molecular activities distinct from its metabolite, phenylacetate (PA). Both PB and PA promote differentiation in human prostate cancer cell lines, yet little data exist comparing the cytotoxic effects of each drug. We found that PB is more potent than PA in vitro; PB is 1.5-2.5 times more active at inhibiting growth and inducing programmed cell death than PA at clinically achievable doses against each human prostate cancer line studied. PB is equipotent to sodium butyrate, which induces apoptosis and differentiation through multiple mechanisms. Exposure of prostate cancer cell lines to PB reduces their DNA synthesis, leads to fragmentation of genomic DNA, and causes 50-60% of cells to undergo apoptosis. These PB-induced effects are 2-10 times greater than those of the control or PA. The stereotypical changes of apoptosis can be seen with sodium butyrate at similar concentrations, but not with PA. Prostate cancer cell lines overexpressing P-glycoprotein or possessing heterogeneous molecular alterations, including p53 mutations, are also sensitive to the effects of PB. In vivo, Copenhagen rats treated with oral PB had delayed growth of the androgen refractory Dunning R-3327 MAT-LyLu prostate cancer subline by 30-45% in a dose-dependent manner. These results demonstrate that PB induces cytotoxicity via apoptosis in human prostate cancer, in addition to its differentiating properties.

Animals↗
PubMed1995

Molecular characterization of defective antigen processing in human prostate cancer.

BACKGROUND: Gene-modified tumor cell vaccines have shown efficacy in animal models of malignancy, including prostate cancer. Class I major histocompatibility complex (MHC) assembly and function in the cellular targets of such therapies is pivotal in determining the efficacy of specific cytokine-secreting tumor vaccines. PURPOSE: To help guide development of genetically engineered vaccine therapy for human prostate cancer, potential immune resistance pathways were evaluated by analysis of class I MHC assembly in prostate cancer cells. METHOD: Class I MHC assembly in metastasis-derived human prostate cancer cell lines (LNCaP, PPC-1, DU-145, PC-3, and TSU) and a normal prostate-derived cell line (TP-2) were characterized by phenotypic, molecular, and functional assays. Assembled class I MHC and antigen was measured by flow cytometry; mRNA levels of assembly components (class I MHC heavy chain, beta 2-microglobulin, and the antigen transporter gene product TAP-2) were determined; and antigen processing was measured with a chimeric reconstituted system using vaccinia vectors. Restoration of antigen processing was attempted by interferon gamma stimulation and by transfection with mouse class I MHC heavy-chain cDNA. RESULTS: Assembled class I MHC was underexpressed in two (LNCaP and PPC-1) of five prostate cancer cell lines compared with normal prostate-derived controls. PPC-1 cells underexpressed TAP-2 mRNA despite abundant class I MHC and beta 2-microglobulin message. Induction of TAP-2 by interferon gamma indicated that coding sequences for TAP-2 message were present in PPC-1. Resistance to cytotoxic T lymphocytes (CTL) lysis showed a functional defect in antigen transport by PPC-1 cells; reversal of the molecular defect with interferon gamma led to restoration of functional antigen processing. In contrast, LNCaP cells had competent antigen transport but deficient class I MHC heavy-chain function despite abundant class I MHC RNA; though refractory to stimulation by interferon gamma, this defect responded to transfection of class I MHC heavy-chain cDNA. CONCLUSIONS: Metastatic prostate cancer cells can escape T-cell recognition via divergent mechanisms of defective class I MHC assembly. The specific underexpression of TAP-2 gene product in PPC-1 cells contrasts with prior studies of TAP gene underexpression in lung cancer (which concurrently underexpressed class I MHC heavy chain) and provides evidence for a regulatory pathway controlling TAP-2 gene expression in human cancers that may not affect class I MHC heavy-chain expression. IMPLICATIONS: In clinical application of gene therapy for prostate cancer, these findings provide a rationale for focusing on strategies that can circumvent sole reliance on class I MHC-mediated tumor cell recognition by CTL.

Antigen Presentation↗
PubMed1995

Serum ferritin as a clinical marker for renal cell carcinoma: influence of tumor volume.

OBJECTIVES: At present, 35% to 50% of patients with clinically localized renal cell carcinoma (RCC) unpredictably have a recurrence after surgical therapy. Presently, no clinical serum marker exists to detect occult metastases and to allow measurement of response to therapy in RCC. Serum ferritin was previously reported to correlate with pathologic stage. We postulated that this increase in serum ferritin with increasing stage might reflect tumor volume, since higher stage tumors are often larger. METHODS: Serum ferritin levels were measured preoperatively in 30 patients with radiologic evidence of RCC. Tumor volume and the largest tumor dimension were calculated from either the pathologic specimen (n = 24) or from the computed tomography or magnetic resonance imaging (n = 30). Pathologic stage was determined for all patients undergoing surgery (T1 = 3, T2 = 12, and T3 = 9). RESULTS: Preoperative serum ferritin levels did not correlate with age, blood urea nitrogen levels, creatinine levels, hematocrit, race, or gender. Although mean serum ferritin levels increased with increasing stage (T1 = 113 +/- 75, T2 = 254 +/- 270, and T3 = 425 +/- 257 ng/mL), these differences did not reach statistical significance (P > 0.05). Serum ferritin did, however, correlate with tumor volume (R = 0.75; P < 0.0001) and the largest tumor dimension measured from radiographic studies (R = 0.8; P < 0.0001). Serum ferritin measured intraoperatively from the renal vein (666 ng/mL) and the inferior vena cava (564 ng/mL) from a patient with a 500 cc tumor (preoperative serum ferritin, 552 ng/mL) suggested that the tumor was the source of the elevated ferritin levels. Histologic sections from tumors taken from patients with high serum ferritin levels were more necrotic and stained intensely positively for iron and immunohistochemically for ferritin, whereas adjacent histologically normal tissue did not. CONCLUSIONS: These data suggest that ferritin may be a useful serum marker for monitoring patients with RCC, but the actual source of the ferritin remains unclear and dictates further investigation.

Adult↗
PubMed1995

Interleukin-6: a candidate mediator of human prostate cancer morbidity.

OBJECTIVES: Interleukin-6 (IL-6) is evaluated as a candidate mediator of morbidity in patients with metastatic adenocarcinoma of the prostate. METHODS: IL-6 concentration is measured by enzyme-linked immunoadsorbent assay (ELISA) in the ejaculate plasma of healthy men, in primary culture of prostate epithelial cells, in human prostate cancer cell line cultures and SCID mouse xenografts, and in the plasma of 73 men with metastatic adenocarcinoma of the prostate. RESULTS: High levels of IL-6 secretion are found in the normal human ejaculate, in prostate epithelial primary culture, and in three of four anaplastic, androgen-independent human prostate cancer cell lines tested. In contrast, the hormone-responsive and PSA-secreting cell lines and the hormone-independent line PPC-1 do not secrete detectable levels of IL-6 by ELISA: The acquisition of a p53 mutation in LNCaP-GW and PPC-1 is not sufficient to confer the phenotype of high IL-6 secretion. Seventy-three men with well-characterized, advanced, hormone refractory prostate cancer prior to suramin therapy are tested for incidence of abnormal circulating levels of IL-6. Plasma IL-6 levels have a bimodal distribution, with the upper quartile of patients having abnormal levels from 9 to 61 pg/mL. A direct comparison of the high and low serum IL-6 groups show that elevated IL-6 levels are strongly correlated with objective measures of morbidity: decreased hematocrit, hemoglobin, and serum cholesterol, and increased white blood cell count and serum lactate dehydrogenase levels all in the absence of clinical infection. CONCLUSIONS: These data show that IL-6 is a prostate exocrine gene product, a candidate mediator of prostate cancer morbidity, and a candidate marker of disease activity for prospective clinical testing.

Adenocarcinoma↗
PubMed1995

Selection of men at high risk for disease recurrence for experimental adjuvant therapy following radical prostatectomy.

OBJECTIVES: Following surgery, men with recurrent prostate cancer have an isolated elevation in serum prostate-specific antigen (PSA) well in advance of measurable metastatic disease. Rational patient selection for new forms of adjuvant therapy, for example, gene therapy, is imperative. METHODS: In a retrospective study of two cohorts, we used proportional hazards regression analysis to develop and validate a multifactor model for identifying men who are at high risk of cancer recurrence. The model cohort consisted of 216 men with clinical Stage T2b and T2c treated by 1 urologist. The validation cohort consisted of 214 men with Stage T2b and T2c disease. RESULTS: A model for log relative risk, Rw, used serum PSA with a sigmoidal transformation (PSAST), radical prostatectomy Gleason score (GS), and pathologic stage (PS) as specimen confined or nonspecimen confined: Rw = (PSAST x 0.06) + (GS x 0.54) + (PS x 1.87). Recurrence risk categories were determined as low risk if Rw is less than 4.0, intermediate risk if it is 4.0 to less than 5.75, and high risk if Rw is more than 5.75. The observed Kaplan-Meier actuarial analysis of the three risk groups correlated well with the predictions determined for the model cohort. We then validated this model independently using a second cohort of 214 men with similar age, stage, and grade treated by 3 different urologists at two different institutions. CONCLUSIONS: The recurrence rates for men in the high-risk group are similar to those for men with positive lymph nodes and justifies exploration of experimental adjuvant therapy within this group using this model of patient selection.

Actuarial Analysis↗
PubMed1995

Identification of endothelin-1 in the pathophysiology of metastatic adenocarcinoma of the prostate.

Prostate cancer is the second most common cause of death from cancer in U.S. men, and advanced, hormone-refractory disease is characterized by painful osteoblastic bone metastases. Endothelin-1, more commonly known as a potent vasoconstrictor, is a normal ejaculate protein that also stimulates osteoblasts. We show here that plasma immunoreactive endothelin concentrations are significantly elevated in men with metastatic prostate cancer and that every human prostate cancer cell line tested produces endothelin-1 messenger RNA and secretes immunoreactive endothelin. Exogenous endothelin-1 is a prostate cancer mitogen in vitro and increases alkaline phosphatase activity in new bone formation, indicating that ectopic endothelin-1 may be a mediator of the osteoblastic response of bone to metastatic prostate cancer.

Adenocarcinoma↗
PubMed1995

Comparison of melanocytes and keratinocytes in ultraviolet-induced DNA damage per minimum erythema dose sunlight: applicability of ultraviolet action spectra for risk estimates.

Action spectra are being used in risk estimates for ultraviolet (UV) damage. The purpose of our investigation was to compare the susceptibility of cultured melanocytes and keratinocytes to UV-induced DNA damage per minimum erythema dose (MED) and to determine whether the predictions made with action spectra agree with the damage actually induced. Genetic damage was measured as the number of T4-endonuclease V-sensitive sites (ESS). Predictions made with the action spectrum for the induction of DNA damage in melanocytes after irradiation with sunlight and a solar simulator were 15.9 and 13.2 ESS per 10(8) daltons per MED, respectively; with the action spectrum for the induction of DNA damage in keratinocytes the predictions were 12.1 and 9.8 ESS per 10(8) daltons per MED, respectively. To determine the actual damage per MED, cultured cells were irradiated with sunlight or a solar simulator, and MED was determined with an erythema UV meter. The induction of DNA damage in melanocytes after sunlight and solar simulator irradiation was 8.01 and 6.7 ESS per 10(8) daltons per MED, respectively, and in keratinocytes 7.49 and 7.12 ESS per 10(8) daltons per MED, respectively. This was considered to be in agreement with the predicted data. The use of action spectra for risk estimates in melanocytes appears justified.

Animals↗
PubMed1995

Genetic, epigenetic, dysgenetic, and non-genetic mechanisms in tumorigenesis.

A not yet understood phenomenon in carcinogenesis is the enormous difference in cancer susceptibility of cells from different species and of cells from individuals within the same species but with different age. Reviewing of the literature points to the promotion phase as the key for this difference. The essence of promotion appears to be a profound switch in the cell functions that enable cells to respond to stresses such as those caused by wounds and infection (cell activation). It was suggested that this switch involves an increase in the life span of the cells which, in turn, may predispose them to immortalization. A relationship of this switch with the onset of genetic instability was suggested, but it is not clear whether genetic instability is inherent to this switch or due to an incorrect performance of either switching on or switching off the response. The cause of species and age-specific differences in cancer susceptibility has therefore been sought in species and age-specific differences on the regulatory control of cell activation, an area that is still largely a black box.

Animals↗