The treatment of malignant mesothelioma with a gene modified cancer cell line: a phase I study

Malignant mesothelioma is a tumor of the pleura for which there is no satisfactory treatment. It is almost universally fatal, regardless of the stage of the tumor at the time of diagnosis. Current treatment modalities include surgery, chemotherapy, and radiation therapy, although in some series none of these modalities is superior to no treatment at all. Because of the dismal prognosis for patients with malignant mesothelioma, a new mode of treatment is desperately needed. A promising area of research into the treatment of various malignancies is gene therapy. Recent studies have demonstrated the utility of exposing tumor cells to cells transduced to express the Herpes simplex virus gene for thymidine kinase (HSV-tk). By virtue of their expression of HSV-tk, the transduced cells are rendered susceptible to the antiviral drug, ganciclovir (GCV). and nearby tumor cells are killed by a phenomenon termed the bystander effect. In this protocol we propose a Phase I trial to study the safety and determine the maximal tolerated dose of an HSV-tk-transduced ovarian cancer cell line (PA1-STK cells) infused into the pleural cavities of patients with malignant pleural mesothelioma, followed by systemic administration of ganciclovir. The hope is that administration of ganciclovir will result in killing of the HSV-tk transduced ovarian cancer cells as well as the nearby malignant mesothelioma cells. This is a standard dose-escalation protocol.

POINT DEFECT CHEMISTRY OF METAL OXIDE HETEROSTRUCTURES

▪ Abstract  This article reviews the defect chemistry of perovskite ferroelectric oxides such as barium titanate and lead zirconate titanate. Such metal oxides are being considered for a wide range of applications that include nonvolatile memories and dynamic random access memories. Time-dependent degradation of these devices is controlled at least in part by point defects, which are determined by the defect chemistry of the material. The role of point defects on Pb(Zr,Ti)O3 thin film device properties such as fatigue, switching, polarization relaxation and imprint is discussed.

Gene therapy for malignant mesothelioma: a novel approach for an incurable cancer with increased incidence in Louisiana

Malignant mesothelioma (MM) is a tumor of the pleura for which there is no satisfactory treatment. It is an almost universally fatal disease, regardless of the stage of the tumor at the time of diagnosis. Current treatment modalities include surgery, chemotherapy, and radiation therapy, although in some series none of these modalities is superior to no treatment at all. Because of the dismal prognosis for patients with MM, new modes of treatment are desperately needed. A promising area of research into the treatment of various malignancies is gene therapy. Recent studies have demonstrated the utility of exposing tumor cells to cells transduced to express the Herpes simplex virus gene for thymidine kinase (HSV-TK). By virtue of their expression of HSV-TK, the transduced cells are rendered susceptible to the antiviral drug, ganciclovir (GCV). Nearby untransduced tumor cells are killed by a so-called bystander effect. We are describing a Phase I clinical gene therapy trial for MM, which we are presently conducting at the Louisiana State University Medical Center of New Orleans. The purpose is to study the safety and to determine the maximal tolerated dose of an HSV-TK-transduced ovarian cancer cell line (PA1-STK cells) that is infused into the pleural cavities of patients. This infusion is followed by systemic administration of GCV. The hope is that administration of GCV will result in killing of both the transduced ovarian cancer cells as well as the nearby malignant cells.

p53 molecule as a prognostic marker in human malignancies

The tumor suppressor gene, p53, is the most commonly mutated gene associated with cancer. Mutation of p53 plays a critical role in the multiple stages of carcinogenesis. The functional inactivation of p53 by missense mutations has been described in various cancers and the majority of these mutations occur in exons 5 through 9 of the p53 gene. Mutations leading to the overexpression of p53 have been found to affect the patient survival outcome in several human malignancies. Our experience with more than 200 samples of breast and prostate carcinoma is presented. Our results strongly suggest that the type and location of the p53 mutations within the molecule may affect and dictate the outcome of cancer.

Identification of mammosomatotrophs in the turkey hen pituitary: increased abundance during hyperprolactinemia

We have previously reported that the hyperprolactinemia in incubating turkey hens is associated with recruitment of lactotrophs in the pituitary gland. In this study we have used double immunofluorescence and in situ hybridization histochemistry to 1) identify mammosomatotrophs in the anterior pituitary gland of egg-laying turkey hens and incubating hens, and 2) verify PRL gene expression within mammosomatotrophs by colocalizing PRL messenger RNA in GH-immunoreactive (ir) cells. The pituitaries of laying and incubating turkey hens were collected, and the midsagittal sections were dual labeled for either PRL and GH or PRL messenger RNA and GH. The plasma PRL concentrations were higher in incubating hens (231 +/- 10.6 ng/ml) than in laying hens (43 +/- 7.4 ng/ml; P < 0.01). In the midsagittal pituitary sections, mammosomatotrophs were predominantly found scattered in the caudal lobe of the anterior pituitary gland, in the ventral half of the cephalic lobe, and at the junction of cephalic and caudal lobes. In incubating hens, the proportion of mammosomatotrophs was 7.4 +/- 1.52% (mean +/- SEM) of the total number of GH-ir and/or PRL-ir cells counted, which was significantly higher (P < 0.05) than that found in laying hens (0.6 +/- 0.23%). Furthermore, PRL gene expression was observed in many GH-ir cells in the incubating hen pituitary gland. These data suggest that 1) mammosomatotrophs are present in the turkey pituitary gland, and 2) there is an increased abundance of mammosomatotrophs in the incubating turkey hen that may contribute to hyperprolactinemia.

Ferroelectric Field Effect Transistor Based on Epitaxial Perovskite Heterostructures

Ferroelectric field effect devices offer the possibility of nonvolatile active memory elements. Doped rare-earth manganates, which are usually associated with colossal magnetoresistive properties, have been used as the semiconductor channel material of a prototypical epitaxial field effect device. The carrier concentration of the semiconductor channel can be "tuned" by varying the manganate stochiometry. A device with La0.7Ca0.3MnO3 as the semiconductor and PbZr0.2Ti0.8O3 as the ferroelectric gate exhibited a modulation in channel conductance of at least a factor of 3 and a retention loss of 3 percent after 45 minutes without power.

Ferroelectric Field Effect Transistor Based on Epitaxial Perovskite Heterostructures

Ferroelectric field effect devices offer the possibility of nonvolatile active memory elements. Doped rare-earth manganates, which are usually associated with colossal magnetoresistive properties, have been used as the semiconductor channel material of a prototypical epitaxial field effect device. The carrier concentration of the semiconductor channel can be "tuned" by varying the manganate stochiometry. A device with La0.7Ca0.3MnO3 as the semiconductor and PbZr0.2Ti0.8O3 as the ferroelectric gate exhibited a modulation in channel conductance of at least a factor of 3 and a retention loss of 3 percent after 45 minutes without power.

Tumor-host interaction: analysis of cytokines, growth factors, and tumor-infiltrating lymphocytes in ovarian carcinomas

The host-tumor interaction may play an important role in determining tumor progress. Recent studies have shown that this interaction can be influenced by the release of soluble factors by tumor cells and tumor-infiltrating lymphocytes (TIL). The aim of our study is to characterize the nature of cytokines and growth factors and their relationship to the cellular infiltrates in 16 patients with ovarian cancer using reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry. Total RNA from 20 malignant and 10 benign specimens were used to assay for expression of 12 cytokines. Additionally, monoclonal antibodies (MAbs) were used to detect T cells, CD4+ helper and CD8+ cytotoxic/suppressor T-cell subtypes, B cells, and macrophages. Our results showed the expression of transforming growth factor-beta1 (TGF-beta1), interleukin-10 (IL-10), and granulocyte-macrophage colony-stimulating factor (GM-CSF) in 19, 17, and 10 malignant specimens, P < .001, .001, and .05, respectively. Other cytokines such as interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), TNF-beta/LT, IL-2, and IL-6 were expressed in a few cases, and IL-1alpha and IL-4 expression were not detected. The benign samples did not express IL-10, but GM-CSF, TGF-beta1, and IL-8 were expressed in one, one, and four specimens, respectively. Interestingly, in four cases in which samples from the primary and relapse tumors were available for analysis, the tumors in relapse showed a significant increase for TGF-beta1 (P < .05) and a decreased trend in IL-10 mRNA levels. The source of these factors was tumor cells as detected immunohistochemically. This combined alteration of TGF-beta1 and IL-10 was associated with a significant reduction in number of TIL in general, and CD8+ and macrophages in particular (P = .036 and .049, respectively). Our findings suggest the important role of certain soluble factors in the complex process of tumor progression. Furthermore, understanding the tumor-host relationship and the factors influencing the interaction may be helpful in developing effective and innovative treatment methods.

Expression of costimulatory molecules: B7 and ICAM up-regulation after treatment with a suicide gene

The herpes simplex virus thymidine kinase gene (HSV-TK) in combination with ganciclovir (GCV), is currently being used in gene therapy-based clinical trials for cancer treatment. Its therapeutic effect is based on a "bystander effect" whereby HSV-TK gene-modified tumor cells are toxic to nearby unmodified tumor cells when exposed to the antiviral drug GCV. We have recently hypothesized that the in vivo mechanism of this bystander effect is due to alterations in the tumor microenvironment in response to release of cytokines and an infiltration of leukocytes after treatment with HSV-TK gene-modified tumor cells and GCV, which results in tumor regression. Expression of B7, a recently identified costimulatory molecule that is important for T-cell stimulation, has been shown to be modulated by stimulatory cytokines interferon-gamma, tumor necrosis factor-alpha, and inhibited by interleukin-10. In the present study, we investigated whether the cytokines released after HSV-TK and GCV treatment could include the expression of the costimulatory molecules B7-1 and B7-2 and the adhesion molecule (ICAM)-1 in the tumor. Furthermore, we investigated whether this altered environment affected the antitumor properties of host lymphocytes. An in vitro model was developed to establish the effects of HSV-TK gene-modified tumor cells and GCV on tumor infiltrating cells. The murine macrophage cell line (IC21) was exposed to either supernatants or cell lysates collected from a mixture of HSV-TK-transduced (KBALB-STK) and non-transduced (KBALB) murine fibrosarcoma tumor cells previously exposed to GCV (experimental). Immunohistochemical analysis showed a significant expression (P < .0001) of B7-1 and B7-2 post exposure of IC21 cells to either supernatant or lysate. In contrast, the level of expression in IC21 cells exposed to the control lysate or supernatant remained unchanged for B7-1 and B7-2. In vivo analysis for B7-1 and B7-2 expression by immunohistochemistry in tumor tissues from experimental mice receiving HSV-TK gene-modified tumor cells and GCV treatment showed a significant expression of B7.1 (35%, P < .0001) and B7.2 (38.2%, P < .0001) on tumor-infiltrating mononuclear cells. In contrast, tumor-bearing control animals showed low levels of B7-2 expression (5.8%), whereas B7-1 was undetectable, as confirmed by reverse-transcriptase polymerase chain reaction. In addition, a significant up-regulation of ICAM expression (50%) on tumor tissues was observed in the experimental group (P = .0317) as compared with the control group (25%). Furthermore, T cells isolated from experimental mice showed a significant in vitro proliferative response (p = .0202) when exposed to syngeneic tumor cells as compared with the control group. These data demonstrated that the use of HSV-TK gene-modified tumor cells and GCV as a suicide gene in the treatment of an intraperitoneal tumor resulted in the expression of the B7 costimulatory molecules and ICAM-1 adhesion molecule and enhanced proliferative response of host T cells. These findings help to understand the mechanism of tumor cell killing in vivo using HSV-TK gene-modified tumor cells.

Changes in pituitary somatotroph and lactotroph distribution in laying and incubating turkey hens

Turkey hens can rapidly shift from a laying condition to one characterized by ovarian regression, incubation behavior, and hyperprolactinemia. Although remarkable changes occur in hormonal profiles as turkey hens pass from a laying to an incubating state, studies have not been undertaken to examine histochemical alterations of functionally relevant pituicytes in the adenohypophysis. The objective of this study was to compare the immunocytochemical changes in pituitary lactotrophs and somatotrophs in incubating turkey hens with those of egg laying hens. Based upon nest visiting and egg production records, laying and incubating hens were selected for sampling blood, pituitaries, and ovaries. Plasma prolactin (PRL) and growth hormone (GH) concentrations were determined. Sagittal pituitary sections of laying and incubating hens were immunostained using antibodies against turkey growth hormone or synthetic chicken PRL peptide. Somatotrophs were found predominantly in the caudal lobe while lactotrophs occurred only in the cephalic lobe of adenohypophysis in laying hens. In incubating hens, somatotrophs in the ventral half of the caudal lobe were replaced by lactotrophs. The sagittal area which immunostained for PRL was significantly greater while the area that immunostained for GH was less in the adenohypophysis of incubating turkey hens. Some of the lactotrophs were hypertrophied in incubating hens. The lactotrophic recruitment and hypertrophy provide a cellular basis for the hyperprolactinemia in incubating turkey hens.

In vivo analysis of the 'bystander effect': a cytokine cascade

The "bystander effect" refers to the death of unmodified tumor cells when in contact with ganciclovir (GCV)-exposed, herpes simplex virus-thymidine kinase (HSV-TK)-modified tumor cells. Although the exact mechanism or mechanisms involved in mediating the bystander effect in vivo are unknown, our findings suggest that an intact host immune system is required for the phenomenon to occur. The present study was designed to establish the effect of HSV-TK-modified tumor cells and GCV on the tumor and its microenvironment in vivo. In sublethally irradiated and immunodeficient Balb/c mice, the bystander effect was observed to be diminished or abrogated. Histopathologic examination of the tumor mass from immunocompetent mice demonstrated centralized hemorrhagic tumor necrosis (38%) after inoculation of the HSV-TK-modified tumor cells and GCV in tumor-bearing mice compared with the control mice (5%), indicating that cytokines such as tumor necrosis factor-alpha (TNF-alpha) were being released locally. This hypothesis was underscored using reverse transcriptase polymerase chain reaction (RT-PCR), by the demonstration of cytokine mRNA expression in mice treated with HSV-TK-expressing tumors and GCV. Semiquantitative PCR analysis for TNF-alpha using PCR-MIMIC on tumor samples from mice treated on days 1 and 4 showed a two-fold increase in the level on mRNA expression. Also, immunohistochemical staining for TNF-alpha showed that mononuclear inflammatory cells infiltrating the tumor were its source. Finally, characterization of tumor-infiltrating lymphocytes (TIL) in experimental animals demonstrated a two- to three-fold increase in the number of macrophages and T cells compared with control animals. These results demonstrate that, in vivo, the bystander effect is mediated in part by an antitumor response through the release of cytokines. Further, the cytokine milieu and tumor microenvironment can be modulated following injection of HSV-TK cells and GCV to enhance the host immune response, which is of potential use in clinical trials.

Changes in pituitary somatotrophs and lactotrophs associated with ovarian regression in the turkey hen (Meleagris gallopavo)

Hyperprolactinemia has been associated with incubation behavior and ovarian regression in turkey hens. Preliminary data show that tamoxifen, a partial estradiol receptor antagonist, may effect ovarian regression. The objectives of the study were to induce ovarian regression in egg-laying turkey hens by administration of tamoxifen, to determine whether incubation behavior would be effected by tamoxifen treatment and to examine the distribution of lactotrophs and somatotrophs and their immunocytochemical changes in the adenohypophysis due to a change in reproductive state. Two commercial strains of turkey hens were administered tamoxifen (experimentals) or vehicle (controls) intramuscularly (40 mg/hen/d). Equal numbers of experimental and control hens were killed for sample collection after 5, 9 and 14 days (n = 4 per strain) of treatment. Blood samples were collected for hormone assay and pituitaries prepared for immunocytochemistry. Tamoxifen treatment for 9 and 14 days induced ovarian regression but not incubation behavior. Plasma luteinzing hormone levels were significantly increased after 5 and 9 days of tamoxifen administration, whereas prolactin and growth hormone levels were unchanged. Somatotrophs were found predominantly in the caudal portion and lactotrophs occurred in the cephalic lobe of the pituitary. Relative to controls, the prolactin immunoreactive area was significantly greater in tamoxifen-treated hens, whereas the growth hormone immunoreactive area was reduced.

Mutations causing high basal level transcription that is independent of transcriptional activators but dependent on chromosomal position in Saccharomyces cerevisiae

Two single (bel2 and bel4) and two double (bel3 bel7 and bel5 be16) mutations causing enhanced transcription of a gene fusion, consisting of the open reading frame of PHO5 connected to the HIS5 promoter (HIS5p) integrated at the ura3 or leu2 locus, were isolated from a gcn4-disrupted mutant of Saccharomyces cerevisiae. The PHO5 gene, encoding repressible acid phosphatase, in the HIS5p-PHO5 construct was derepressed under amino acid starved conditions by the action of the transcriptional activator Gcn4p. The bel mutants showed temperature-sensitive cell growth and/or cell aggregation. All the mutants except bel4 also showed high levels of transcription of an intact PHO5 DNA integrated at the URA3 locus in the absence of the cognate transcriptional activator, Pho4p, and in the absence of upstream activating sequences of PHO5. The HIS5 and PHO5 genes at their original chromosomal positions were, however, not affected by the bel2 mutation. The BEL2 gene was found to be identical with SIN4/TSF3, mutations in which cause high levels of transcription of the HO and GAL genes in the absence of their respective transcriptional activators, Swi5p and Gal4p. The effect of the bel2/sin4/tsf3 mutation on PHO5 transcription was additive with the Pho4p function. Thus the effect of the bel2/sin4/tsf3 mutation is dependent on the position of PHO5 in the chromosome and independent of Pho4p and Gen4p activation.