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Biomedical subjects

L M Glode

Publications and source records attributed to L M Glode.

At least 19 recordsLinked to original sources
PubMed2004

Gonadotropin-releasing hormone and its receptor in normal and malignant cells.

Gonadotropin-releasing hormone (GnRH) is the hypothalamic factor that mediates reproductive competence. Intermittent GnRH secretion from the hypothalamus acts upon its receptor in the anterior pituitary to regulate the production and release of the gonadotropins, LH and FSH. LH and FSH then stimulate sex steroid hormone synthesis and gametogenesis in the gonads to ensure reproductive competence. The pituitary requires pulsatile stimulation by GnRH to synthesize and release the gonadotropins LH and FSH. Clinically, native GnRH is used in a pump delivery system to create an episodic delivery pattern to restore hormonal defects in patients with hypogonadotropic hypogonadism. Agonists of GnRH are delivered in a continuous mode to turn off reproductive function by inhibiting gonadotropin production, thus lowering sex steroid production, resulting in medical castration. They have been used in endocrine disorders such as precocious puberty, endometriosis and leiomyomata, but are also studied extensively in hormone-dependent malignancies. The detection of GnRH and its receptor in other tissues, including the breast, ovary, endometrium, placenta and prostate suggested that GnRH agonists and antagonists may also have direct actions at peripheral targets. This paper reviews the current data concerning differential control of GnRH and GnRH receptor expression and signaling in the hypothalamic-pituitary axis and extrapituitary tissues. Using these data as a backdrop, we then review the literature about the action of GnRH in cancer cells, the utility of GnRH analogs in various malignancies and then update the research in novel therapies targeted to the GnRH receptor in cancer cells to promote anti-proliferative effects and control of tumor burden.

Animals↗
PubMed2001

Internet oncology: increased benefit and risk for patients and oncologists.

Whether the benefits will outweigh the risks of electronic health care remains to be seen, and to a large extent the question is moot; consumers, providers, and interested third parties have ensured its existence. One can surmise, or at least hope, that all interested parties will become increasingly sophisticated in both the delivery and consumption of e-health information, and that ultimately consumer, advocate, and physician demands will help shape the industry into a self-regulated entity that balances the need for high-grade information with a commitment to the principles of privacy and autonomy.

Computer Literacy↗
PubMed2000

Comparison of telomerase activity and GSTP1 promoter methylation in ejaculate as potential screening tests for prostate cancer.

New diagnostic tools are needed for the early detection of prostatic cancer. The molecular detection of prostate cancer cells in ejaculates was evaluated using complementary PCR-based methods. LNCaP cells, a cell line derived from prostatic carcinoma, were spiked into normal seminal ejaculates and the prostatic epithelial component of the specimens was isolated by immunomagnetic bead sorting, using a monoclonal antibody to prostate-specific membrane antigen (PSMA). Ejaculates from nine patients with a recent diagnosis of prostate cancer were processed in a similar fashion, using LNCaP-spiked aliquots as an internal positive control. Telomerase expression was evaluated by the telomeric repeat amplification protocol (TRAP) and glutathione S-transferase gene promoter (GSTP1) hypermethylation was evaluated by methylation-sensitive restriction endonuclease digestion and PCR amplification. Telomerase activity was detected in LNCaP cells recovered from normal seminal ejaculates but was not found in all nine samples from patients with prostate cancer. The sensitivity of GSTP1 analysis was similar to telomerase analysis for the detection of LNCaP cells from normal ejaculate samples but was positive in ejaculates from four out of nine patients with prostate cancer. GSTP1 DNA methylation status is more sensitive than telomerase analysis for the detection of malignant cells in seminal ejaculates from patients with prostate cancer.

DNA Methylation↗
PubMed2000

Recombinant Semliki forest virus infects and kills human prostate cancer cell lines and prostatic duct epithelial cells ex vivo.

Semliki Forest Virus (SFV) is a broad host range RNA virus capable of high-level recombinant protein expression and apoptosis induction in many cell types. We have successfully used a recombinant, replication deficient SFV vector to express the LacZ marker gene product in seven human prostate cell lines, as well as in human prostate tissue explants. Flow cytometry revealed that 40-60% of PPC-1 prostate cancer cells died 24-72 h after infection with SFV-LacZ virus. Most human prostate cancer cell lines expressed high levels of recombinant protein. Infection of human prostate tissue ex vivo led to similarly high expression levels but the recombinant beta-galactosidase was confined to duct epithelial cells. Infection of cell and tissue cultures resulted in detachment of adherent cells from the culture surface and detachment of epithelial cells from the basement membrane of tissue. Our results indicate that SFV may be useful in targeting recombinant protein expression and apoptosis to prostatic duct epithelial cells.

Apoptosis↗
PubMed1999

Refractory disease, new horizons and patient-physician relationships.

Understanding the role of chemotherapy for prostate cancer has advanced along two axes, better definition of endpoints, and biologic understanding of disease targets. Use of PSA as a surrogate endpoint makes possible the more rational design of phase III trials which will include survival and disease free intervals as an endpoint. Pain control has emerged as an important treatment endpoint through which more cost-effective care can be envisioned. Discovery of growth factor interactions with prostate cancer cells and the elucidation of apoptotic pathways have provided numerous new targets for biologic and chemotherapy of advanced disease.

Journal Article↗
PubMed1997

In vitro expression of the diphtheria toxin A-chain gene under the control of human chorionic gonadotropin gene promoters as a means of directing toxicity to ovarian cancer cell lines.

OBJECTIVE: Our goal was to determine whether toxicity of the diphtheria toxin A-chain gene regulated by the human chorionic gonadotropin promoter can be directed to malignant ovarian cell lines. STUDY DESIGN: Plasmids containing diphtheria toxin A-chain gene linked to the regulatory elements of the metalloergothioneine and human chorionic gonadotropin promoters were transfected into the cell lines. Expression of diphtheria toxin A-chain gene was determined by the inhibition of a cotransfected luciferase reporter gene. RESULTS: Cytotoxicity of the diphtheria toxin A-chain gene is shown in a dose-responsive manner. Transfection of a plasmid expressing the diphtheria toxin A-chain gene controlled by a constitutive promoter readily inhibits protein synthesis. Specific inhibition of luciferase protein synthesis occurs in ovarian cancer cells transfected with the diphtheria toxin A-chain gene under the control of the human chorionic gonadotropin promoters when compared with normal ovarian epithelial cells or fibroblasts. CONCLUSIONS: These data demonstrate the preferential expression of the diphtheria toxin A-chain gene, regulated by the human chorionic gonadotropin promoter, to ovarian cancer cell lines. This provides an avenue for targeting such cells for suicide, toxin, or cytokine genes.

Carcinoma↗
PubMed1997

Current challenges of gene therapy for prostate cancer.

Gene therapy for prostate cancer faces hurdles similar to those being encountered for other cancers and nonmalignant processes. The greatest obstacle is the identification of efficient delivery systems, since numerous animal models and cell culture systems have shown potential efficacy when most cells express the introduced genetic material. Early prostate cancers are easily accessible to gene vector introduction, and the predictable metastatic patterns of this cancer may offer additional advantages for gene therapy. This article reviews gene vectors and gene products, as well as ongoing trials of gene therapy that have recently begun in prostate cancer.

Animals↗
PubMed1995

Macrophage colony-stimulating factor complementary DNA: a candidate for gene therapy in metastatic melanoma.

BACKGROUND: At present, there is no highly effective treatment for metastatic melanoma. Innovative approaches aimed at inducing a more effective immune response against tumors have shown promising results in animal models. One approach involves the genetic modification of tumor cells so that they produce cytokines that stimulate an immune response. PURPOSE: The aim of this study was to determine the effectiveness of cytokine gene therapy for metastatic melanoma in a murine melanoma model. METHODS: B16F10 murine melanoma cells, which readily metastasize to the lungs, were transduced with a retroviral vector containing genes encoding neomycin resistance and human macrophage colony-stimulating factor (M-CSF). The presence of M-CSF messenger RNA in transduced cells was examined by coupled reverse transcription and polymerase chain reaction. Concentrations of soluble M-CSF in cell culture supernatants were determined by enzyme-linked immunosorbent assays (ELISAs). A clonal cell line, designated N+/CSF+, that expressed and secreted M-CSF was identified. Another clonal cell line, designated N+/CSF-, did not secrete M-CSF at levels detectable by ELISA. B16F10, N+/CSF-, and N+/CSF+ cells, individually or in combination, were injected intravenously or subcutaneously into C57BL/6 mice; we then evaluated the tumorigenicity and metastatic behavior of the cells, as well as the immune responses and survival of the mice. The immune responses assayed were the cytotoxic T lymphocyte (CTL) and peritoneal exudate cell (PEC) tumoricidal activities. RESULTS: Injection of B16F10 cells into the tail vein of C57BL/6 mice led to the establishment of lung metastases by week 2 and death by week 8. Injection of the N+/CSF+ or N+/CSF- cells led to the establishment of lung metastases that were detected at 2 and 3 weeks, respectively; however, these metastatic lesions were eliminated, and the animals had survival rates similar to those of the noninjected control mice. Injection of mice with a mixture of B16F10 and N+/CSF- cells resulted in the development of metastatic disease and 0% survival at 8 weeks, whereas mice that had been given an injection of a mixture of B16F10 and N+/CSF+ cells had an 80% survival rate at 8 weeks and survived at least two times longer (P = .007). The CTL and PEC tumoricidal activities in animals given an injection of N+/CSF+ cells suggested that monocytes and lymphocytes were responsible for the observed antitumor response. CONCLUSION: These findings suggest that the expression of M-CSF by genetically modified melanoma cells caused an effective antitumor immune response in host C57BL/6 mice and, thus, prolonged survival over that observed in the control mice.

Animals↗
PubMed1994

Gene therapy for B-cell lymphoma in a SCID mouse model using an immunoglobulin-regulated diphtheria toxin gene delivered by a novel adenovirus-polylysine conjugate.

Despite advances in conventional therapy, many lives continue to be lost to common forms of B-cell cancers, including leukemias, lymphomas and multiple myeloma. We propose a novel approach to therapy of such cancers using controlled expression of a diphtheria toxin gene (DT-A) to kill malignant cells. We have previously demonstrated selective killing of various cell types, in vitro and in vivo, by cell-specific, transcriptionally controlled expression of this gene. Organ-specific ablation in otherwise healthy transgenic mice has convincingly demonstrated the exquisite specificity achievable by this technique. In the studies now described, DT-A was delivered in vitro and in vivo using a novel gene delivery system employing DNA physically attached to the exterior of adenovirus. After demonstrating the efficacy of gene delivery to Epstein-Barr virus transformed human B-cells in vitro, in vivo work was performed using a SCID mouse model for B-cell lymphoma, in which protection against tumor was observed. The concepts of tissue-regulated toxin gene therapy, and this novel adenovirus gene delivery system are discussed.

Adenoviridae↗
PubMed1992

Phase II evaluation of coumarin (1,2-benzopyrone) in metastatic prostatic carcinoma.

The unavailability of effective treatment of metastatic hormone refractory prostatic carcinoma warrants trials of new and promising treatments. Coumarin is an investigational new drug that has produced objective tumor regression in some patients with metastatic renal cell carcinoma and malignant melanoma. Coumarin has shown activity against prostatic carcinoma in the Dunning R-3327 rat prostatic adenocarcinoma model. Forty-eight patients with metastatic hormone naive (5 stage D1 and 10 stage D2) or hormone refractory (33 stage D3) prostatic carcinoma of average age 67.6 years (range 46-86) and ECOG performance status of 2 or better were given 3 grams coumarin daily by mouth and evaluated monthly for toxicity and response by rigid criteria in a multicenter trial. Toxicity was limited to asymptomatic SGOT elevations in 3 patients and nausea and vomiting in 4 patients that required cessation of therapy in 2. Eligibility and protocol violations removed 6 additional patients from response evaluation. There were no complete responses. Partial responses (3 of 40 patients, 8%) occurred in 2 patients with bidimentionally measurable disease and 1 patient with disease evaluable by bone scan and elevated prostate specific antigen and prostatic acid phosphatase. The remaining patients progressed after 1 to 12 (average 4.4) months. Coumarin is a relatively nontoxic drug that may warrant further trials in a subset of patients with prostatic carcinoma.

Adult↗
PubMed1992

Inhibition of HIV production in cells containing an integrated, HIV-regulated diphtheria toxin A chain gene.

Construction of a DNA plasmid that expresses a diphtheria toxin A chain (DT-A) gene under control of human immunodeficiency virus (HIV-1) proteins Tat and Rev has been described. Here the generation of HeLa cell clones containing integrated, HIV-regulated DT-A sequences is reported. Five such clones were identified by their decreased expression of a luciferase reporter gene transiently cotransfected with Tat- and Rev-encoding plasmids. The decreased luciferase expression most probably was due to activation of the integrated DT-A gene because higher luciferase activity could be restored by introducing either DT antitoxin or a gene encoding a mutant, DT-resistant elongation factor 2 (the intracellular target for DT-A). Analysis by polymerase chain reaction (PCR) indicated that all clones expressed DT-A encoding RNA. The clones were then transfected with an HIV proviral clone and were tested for HIV production; all five clones demonstrated substantially impaired HIV production compared with parental HeLa cells, as shown by p24 assays of culture supernatants. Our success in generating these cell lines indicates that extremely low basal expression has been achieved in view of the high cellular lethality of DT-A. HIV-regulated expression of DT-A may be applicable as a gene therapy approach for the acquired immune deficiency syndrome (AIDS), to bring about selective suicide of HIV-infected cells before production of viral progeny.

Cloning, Molecular↗
PubMed1992

Expression of diphtheria toxin A-chain in mature B-cells: a potential approach to therapy of B-lymphoid malignancy.

Specifically targeted expression of a toxin gene potentially represents a novel approach to cancer therapy. With a view to the ablation of B-cell malignancies, we have constructed a plasmid, designated pTHA71, which expresses the A-chain of diphtheria toxin (DT-A) with high efficiency and specificity in transfected, mature B-lymphoid cells. The construction incorporated immunoglobulin (Ig) kappa light chain gene regulatory sequences, including a kappa promoter, small intron, partial constant region exon, and 3'-flanking sequence (but lacking a known enhancer). These sequences conferred substantially more efficient expression of DT-A in mature B-cells than was seen from constructs that included only Ig promoters and enhancers. When transfected into the 70Z/3 murine pre-B-cell line, pTHA71 was only expressed efficiently if the cells were induced to express their endogenous, rearranged Ig kappa gene by prior exposure to lipopolysaccharide. The insertion of the enhancer from the Ig kappa large intron into pTHA71, generating pTHA81, did not markedly influence the level of DT-A expression in 70Z/3 cells. The observed absence of expression in pre-B-cells suggests that DT-A constructs similar to pTHA71 might be used for the therapeutic ablation of malignant B-cells of mature stages, while sparing normal progenitor cells.

Animals↗
PubMed1991

Expression of the diphtheria toxin A-chain coding sequence under the control of promoters and enhancers from immunoglobulin genes as a means of directing toxicity to B-lymphoid cells.

Previous results have shown that cells can be killed by the expression of an introduced gene encoding diphtheria toxin A-fragment (DT-A) and that killing can be targeted using tissue-specific transcriptional regulatory elements. Here, we describe expression plasmids containing the DT-A gene linked with promoters and enhancers from immunoglobulin heavy chain or kappa-light chain genes. When these plasmids were transfected into cultured cells, DT-A was expressed in B-lymphoid cells but not detectably in HeLa cells or fibroblasts. A high specificity for B-cells was confirmed by assaying for luciferase reporter gene expression from a plasmid containing an analogous combination of immunoglobulin heavy chain regulatory elements. A plasmid containing an immunoglobulin-kappa promoter and enhancer was substantially less active in expressing DT-A in a pre-B-cell line than in B-lymphoma cells, suggesting the possibility of targeting DT-A expression to mature, malignant B-cells while sparing normal B-cell progenitors. By means of viral delivery vehicles, the constructs described might be applied in gene therapy for B-cell leukemias or lymphomas.

Animals↗
PubMed1991

Activation of a diphtheria toxin A gene by expression of human immunodeficiency virus-1 Tat and Rev proteins in transfected cells.

Expression of a gene encoding the diphtheria toxin A (DT-A) fragment, controlled by tissue specific regulatory elements, has previously been used to kill selected cell populations. Here, we have examined the feasibility of controlling DT-A expression using regulatory systems from the human immunodeficiency virus (HIV-1) genome. Plasmids were constructed which express either DT-A or, as a model system, the luciferase (luc) reporter gene, under control of HIV-1 long terminal repeat (LTR) sequences (-167 to +80). While trans-activation by expression of the viral protein Tat was demonstrated, significant basal expression was observed. To reduce basal expression, cis-acting negative regulatory elements from the env region of the HIV-1 genome were inserted in the 3' untranslated region of both the luc and DT-A constructs. This dramatically reduced basal expression from the HIV LTR, and now both viral regulatory proteins Tat and Rev were required for maximal trans-activation. Such regulation of DT-A expression might be therapeutically applied to selectively kill HIV-infected cells in acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC).

Diphtheria Toxin↗
PubMed1991

Construction and expression of plasmids containing mutated diphtheria toxin A-chain-coding sequences.

We previously demonstrated that cells can be killed through transfection of an expression plasmid that encodes the diphtheria toxin A-chain fragment (DT-A). This report describes the construction of expression plasmids containing three mutant DT-A-coding sequences substituting glutamic acid 148 with aspartic acid, serine, or glutamine which are known to have 100- to 300-fold-reduced ADP-ribosylation activity measured in vitro. The toxicity of these constructs was determined in cotransfection experiments using HeLa and 293 cells with a luciferase expression plasmid as the reporter. Dose responses were compared for the three new DT-A mutant plasmids and for the corresponding plasmids containing wild-type DT-A and the previously characterized tox 176 mutant. The dose required to produce 50% inhibition of control luciferase expression in 293 embryonic kidney cells for the five plasmids ranged from 0.01 micrograms for wild-type DT-A to 1.2 micrograms for the least toxic plasmid, which replaces glutamic acid 148 with glutamine. In conclusion, a wide range of DT-A toxicity can be achieved by using plasmid expression vectors that encode different DT-A mutations.

Diphtheria Toxin↗
PubMed1991

Targeted ablation of pituitary gonadotropes in transgenic mice.

LH, FSH, and TSH are heterodimeric glycoprotein hormones composed of a common alpha-subunit and unique beta-subunits. The alpha-subunit is produced in two distinct specialized cell types of the pituitary gland: gonadotropes, which synthesize LH and FSH, and thyrotropes, which synthesize TSH. We have demonstrated that 313 base pairs of the bovine-alpha subunit promoter direct expression of diphtheria toxin A chain specifically to the gonadotropes in transgenic mice. Animals carrying this transgene generally exhibit reproductive failure and lack of gonadal differentiation, consistent with gonadotrope ablation. Lack of gonadotrope activity was verified by RIA and immunohistochemical staining for LH. The phenotype of these transgenic mice is nearly identical to mice homozygous for the spontaneous mutation, hpg, which is due to a deletion in the gene encoding GnRH. Thyrotrope function was judged normal based on overall growth of the animals, appearance of their thyroids, T4 levels measured by RIA, and immunohistochemical staining for TSH. The ablation of gonadotropes but not thyrotropes suggests that separate cis-acting elements are necessary for expression of the alpha-subunit gene in these two cell types. Pituitary content of ACTH and GH was apparently normal, while PRL synthesis and storage were reduced. Thus, in a pituitary almost completely devoid of gonadotropes, most other pituitary functions were normal. This suggests that most pituitary cells are able to differentiate independently of terminal gonadotrope differentiation and can function in the absence of paracrine signaling provided by gonadotropes.

Adrenocorticotropic Hormone↗