Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0376358 (prostate cancer)
 59,338 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Androgen ablation using hormonal manipulation is used extensively in metastatic prostate cancer; however, its use in localized disease combined with surgical extirpation of the gland has not been thoroughly and systematically investigated. The rationale for neoadjuvant therapy stems from the demonstrated effectiveness of androgen ablative therapy in metastatic disease and the high rate of "positive" surgical margins, especially in patients with Stage B2 disease. In addition, the essentially anecdotal clinical report of Scott and Boyd [1], using endocrine therapy plus radical prostatectomy in patients with Stage C disease, gives 15 year survival results comparable to those obtained by Jewett [2] in Stage 1 patients treated by radical prostatectomy. Finally, experimental observations in the androgen-sensitive mammary tumor (Shionogi) lend support to the concept of neoadjuvant hormonal manipulation. A pilot study of neoadjuvant endocrine therapy in 55 patients treated at Memorial Sloan-Kettering Cancer Center with 3 months of diethylstilbestrol (DES) (3 mg/day) prior to radical prostatectomy indicates marked reductions in prostate-specific antigen (PSA), although persistent evidence of adverse local tumor features was common. Some patients, however, exhibited evidence of significant downstaging. Whether or not any alteration in disease progression will accrue from demonstrated local downstaging is, of course, uncertain. However, clinical and laboratory effects of such treatment may provide a means for correlation with subsequent tumor behavior, and may prove useful in treatment decisions. Additionally, a decrease in the number of foci of grade 3 prostatic intraepithelial neoplasia (PIN-3) was noted in a small number of patients.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Neoadjuvant hormonal manipulation: a strategy for chemoprevention trials. 128 66

Androgen-dependent normal prostatic glandular cells and androgen-dependent prostatic cancer cells can be induced to undergo cell death after androgen ablation. This death does not require the cells to proliferate and occurs as an energy-dependent process collectively referred to as "programmed cell death" in which the cells actively commit "suicide." Associated with this programmed cell death pathway is the enhanced expression of a series of genes and the fragmentation of the genomic DNA into nucleosomal oligomers. This genomic DNA fragmentation is the irreversible commitment step in the death of the cell and results from activation of Ca2+/Mg(2+)-dependent endonuclease activity within the cell nucleus. This activation is due to sustained elevation of intracellular free Ca2+ (Cai) induced after androgen ablation. Metastatic prostatic cancer within an individual patient is heterogeneous, including both androgen-dependent and -independent cancer cells. Thus, androgen ablation is rarely curative since it only induces the programmed death of the androgen-dependent cancer cells without activating this pathway in the androgen-independent cancer cells within the patient. Androgen-independent prostatic cancer cells do not activate this death process after androgen ablation, since this does not induce a sustained increase in Cai. A new approach to treat androgen-independent prostatic cancer cells has focused on the use of chemotherapeutic agents to induce a sustained increase in Cai. These studies demonstrate that if such a sustained elevation in Cai is maintained, even androgen-independent prostatic cancer cells undergo programmed cell death.
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PMID:Androgen regulation of programmed death of normal and malignant prostatic cells. 129 27

Steroid hormones have an important role in prostate biology. Androgens are crucial for the normal development of the prostate gland and in maintaining its functional state in the adult. It seems that the prolonged presence of androgens might also be an important factor in the development of prostate cancer. In addition, androgens and oestrogens appear to play some part in the development of benign prostatic hyperplasia, although the exact nature of their role has not been clearly defined. Stimulation of prostate cancer growth by androgens is well established, with androgen withdrawal therapy constituting the most effective therapy in men with prostate cancer. Additive steroid therapy of metastatic prostate cancer with oestrogens or progestins has also proven effective. The effects of androgens on prostate cancer cell growth might be mediated through modulation of growth factor expression and alteration of growth factor receptor levels. Androgen response can be modulated by the expression of mutated oncogenes such as ras. Androgen independence can occur through a loss of AR expression or mutation of the AR; however, the patterns of AR expression in normal prostatic tissue from development to adulthood and in cancer are now just beginning to be described. Other steroids, such as the retinoids, show promise as preventive agents, possibly through the modulation of growth factors.
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PMID:The importance of steroid hormones in prostate cancer. 142 27

The significance of apoptosis in relation to the development and progression of prostate cancer remains largely undefined. bcl-2 is an oncogene that functions by overriding apoptosis. bcl-2 expression was localized to the basal epithelial cells in the normal human prostate with the use of immunohistochemistry. Androgen-dependent and androgen-independent prostate carcinomas were evaluated immunohistochemically for bcl-2 expression. bcl-2 was undetectable in 13 of 19 cases of androgen-dependent cancers. In contrast, androgen-independent cancers displayed diffuse, high levels of bcl-2 staining (P < 0.01). In rats, steady-state levels of bcl-2 mRNA, assessed by S1 assays, reached maximum levels 10 days following castration. Addition of exogenous testosterone with, or without, flutamide demonstrated that the increased bcl-2 mRNA resulted from androgen ablation. Our findings indicate that bcl-2 expression is augmented following androgen ablation and is correlated with the progression of prostate cancer from androgen dependence to androgen independence.
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PMID:Expression of the protooncogene bcl-2 in the prostate and its association with emergence of androgen-independent prostate cancer. 145 83

The leading cause of cancer in males in the United States, prostate cancer accounts for 22% of all new cancers, with 132,000 new cases projected to be diagnosed in 1992. While localized prostate cancer can be cured, up to two thirds of patients present with advanced disease. Androgen deprivation remains the mainstay of treatment for advanced prostate carcinoma. Recurrent disease, however, is invariably refractory to further hormone manipulations. The development of hormone-resistant tumor cells may be explained either by a multi-clones theory, by mutation of previously sensitive tumor cell clones, or, most likely, by both mechanisms. Thus, vigorous efforts are needed to develop nonendocrine treatment approaches. Such efforts have been complicated by the difficulty of assessing therapeutic response in patients with prostate cancer, because the typical metastatic bone lesions seen in these patients are difficult to measure accurately and patients seldom have disease in the lung, lymph nodes, or soft tissue. A variety of single chemotherapeutic agents have been tested against recurrent disease, with widely divergent response rates achieved. Trials of chemohormonal therapy have likewise proved disappointing to date. Preliminary results from an ongoing trial of oral etoposide in patients with recurrent prostate cancer are discussed.
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PMID:Etoposide in the treatment of hormone-refractory advanced carcinoma of the prostate. 148 54

The gene for the androgen receptor (AR) in the androgen-sensitive human prostate cancer cell line LNCaP has a single-base mutation that produces a threonine to alanine change in the androgen-binding domain. Androgen-insensitive prostatic cancer (PC-3) cells were cotransfected with an expression vector encoding normal, LNCaP, or chimeric normal/LNCaP AR and a vector carrying a chloramphenicol acetyltransferase (CAT) reporter gene linked to the mouse mammary tumor virus promoter. CAT activity was specifically induced by androgens in PC-3 cells expressing normal AR. In PC-3 cells expressing LNCaP AR, however, CAT activity was also induced by progestins and the antiandrogen hydroxyflutamide, which had little activity in cells expressing normal AR. Steroid-binding competition assays using in vitro synthesized ARs showed that LNCaP AR had a higher affinity than normal AR for progestins, 17 beta-estradiol, and hydroxyflutamide. The antiprogestin and antiglucocorticoid RU 38486 induced CAT activity in PC-3 cells expressing normal AR but not LNCaP AR. These studies indicate that AR mutations may be very important in determining the appropriate method of treatment with steroid hormones or their antagonists.
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PMID:Expression and function of normal and LNCaP androgen receptors in androgen-insensitive human prostatic cancer cells. Altered hormone and antihormone specificity in gene transactivation. 166 32

Androgen (AR), progesterone (PR), and estrogen (ER) receptor contents in cytosol and salt-extractable nuclear subcompartments from 6 normal, 39 benign hyperplastic (BPH), and 7 malignant prostatic tissue specimens were analyzed by radioligand-binding assay techniques. In addition, the temperature stability of AR and PR was measured in another three BPH specimens. Five punch-needle biopsy samples from prostate cancers were also analyzed for AR and PR content. All receptor data were calculated from saturation analyses. The highest AR content was found in the cytosol and nucleic from malignant prostatic tissues. The highest PR concentrations were found in BPH cytosol, whereas nuclei of all types of tissues were negative with regard to this receptor. Markedly lower concentrations of ER were found in cytosol and nuclei from BPH as compared with malignant and normal tissues. PR was the most temperature-stable receptor; a marked receptor loss at room temperature was not registered until after 12 h. AR was stable for 4-5 h in cytosol and for 8-9 h in nuclei. Needle-biopsy specimens from prostate cancer showed highly variable and confusing results for AR and PR content, indicating that microassay studies using biochemical techniques on small tissue samples are unreliable and should not be recommended.
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PMID:Steroid receptor profile and receptor stability in subfractions of human prostatic tissues. Critical aspects on microassays. 172 52

Fifteen patients with previously untreated metastatic prostate cancer were treated on a pilot trial with a combination of maximal androgen blockade plus intermittent cytotoxic therapy after androgen priming to stimulate cell division. Androgen blockage was carried out using a gonadotropin-releasing hormone analog (leuprolide) plus a nonsteroidal antiandrogen (flutamide). Carboplatin (CBDCA) (800 mg/m2) was given intravenously every 28 days, preceded for 3 days and followed for 3 days by androgen treatment with fluoxymesterone (5 mg orally twice a day), during which time flutamide was discontinued. Three patients (20%) achieved a complete response (CR), and eight patients (53.3%) achieved a partial response (PR). Four patients (26.7%) had stable disease (SD). The median progression-free survival (PFS) time was 31 months. Nine of 15 patients (60%) remain alive with a median follow-up time of 42+ months (range, 22 to 54 months). Grade 4 thrombocytopenia and Grades 3 or 4 leukopenia were experienced in 87% and 80% of patients, respectively, requiring dose reductions of CBDCA in 85% of the cycles. Six of 15 patients experienced a flare in bone pain with androgen priming. There were no associated spinal cord compressions; however, exclusion of impending spinal cord compression was required before entrance on study.
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PMID:A pilot trial of chemohormonal therapy for metastatic prostate carcinoma. 172 65

To increase survival of men with metastatic prostatic cancer, a modality that can effectively eliminate androgen independent cancer cells is desperately needed. By combining such an effective modality with androgen ablation, all of the heterogeneous populations of tumour cells within a prostatic cancer patient can be affected, thus optimizing the chances of cure. Unfortunately, such effective therapy for the androgen independent prostatic cancer cell is not yet available. This therapy will probably require two types of agents, one having antiproliferative activity affecting the small number of dividing androgen independent cells, and the other able to increase the low rate of cell death among the majority of non-proliferating (ie interphase) androgen independent prostatic cancer cells present. Androgen dependent prostatic epithelial cells can be made to undergo programmed death by means of androgen ablation, even if the cells are not in the proliferative cell cycle. Androgen independent prostatic cancer cells retain the major portion of this programmed cell death pathway, only there is a defect in the pathway such that it is no longer activated by androgen ablation. If the intracellular free Ca2+ is sustained at an elevated level for a sufficient time, androgen independent cells can be induced to undergo programmed death. The long term goal is therefore to develop some type of non-androgen ablative method that can be used in vivo to induce a sustained elevation in Ca2+ in androgen independent prostatic cancer cells. To accomplish this task, a more complete understanding of the biochemical pathways involved in programmed cell death is urgently needed. At present, studies are focusing on the mechanism involved in the Ca2+ elevation in the normal and malignant androgen dependent cell induced following androgen ablation and the role of the TRPM-2 protein in this process.
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PMID:Programmed cell death as a new target for prostatic cancer therapy. 184 55

Androgen ablation induces an energy-dependent process of programmed death in nonproliferating androgen-dependent prostatic cancer cells which involves fragmentation of genomic DNA into nucleosomal oligomers catalyzed by nuclear Ca2+, Mg(2+)-dependent endonuclease enzymes activated following a sustained elevation in intracellular free Ca2+ (Cai). In contrast, androgen-independent prostatic cancer cells are not induced to undergo such programmed cell death by androgen ablation. One explanation for the inability of androgen ablation to induce programmed death of androgen-independent prostatic cancer cells is that such ablation does not result in a sustained elevation in Cai in these cells. This raises the issue of whether androgen-independent prostatic cancer cells can be induced to undergo programmed death if an elevation in the Cai is sufficiently sustained by nonhormonal means. To test this possibility, androgen-independent, highly metastatic Dunning R-3327 AT-3 rat prostatic cancer cells were chronically exposed in vitro to the calcium ionophore ionomycin to sustain an elevation in their Cai. These studies demonstrated that an elevation of Cai as small as only 3-6-fold above baseline can induce the death of these cells if sustained for greater than 12 h. Temporal analysis demonstrated that the death of these cells does not require cell proliferation and involves Ca(2+)-induced fragmentation of genomic DNA into nucleosome-sized pieces as the commitment step in this process. These results demonstrate that even nonproliferating androgen-independent prostatic cancer cells can be induced to undergo programmed cell death if a modest elevation in the Cai is sustained for a sufficient time. These observations identify Cai as a potential target for therapy for androgen-independent prostatic cancer cells.
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PMID:Programmed death of nonproliferating androgen-independent prostatic cancer cells. 187 14


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